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Supplementary Figure 4 from Estrogen Suppresses MLK3-Mediated Apoptosis Sensitivity in ER+ Breast Cancer Cells

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Supplementary Figure 1 from Estrogen Suppresses MLK3-Mediated Apoptosis Sensitivity in ER+ Breast Cancer Cells

RiboNucleic Acid (RNA) occupies the center position in the central dogma of molecular biology. These are the nucleotide with a ribose sugar and are found either in linear or circular form. The linear RNAs are of different types and include ribosomal RNA (rRNA), messenger RNA (mRNA), transfer RNA (t-RNA), small nuclear (snRNA) RNA, and very small/micro RNA (microRNAs). The circular (circRNA) RNA is a group of noncoding RNA, stable molecules, established recently and linked with the regulation of different genes, RNAs including microRNAs. The current understanding of these molecules suggests that these circRNAs are fairly conserved and show tissue-specific expression patterns. These molecules are connected with different pathogenic conditions and associated with verities of diseases, including cancer. CircRNAs are thus contributing to tumorigenesis, and these molecules show the potential to become future predictive biomarkers for diagnosis, prognosis and even can be targeted in personalized therapy. Hence, these bio-molecules will get exposed frequently, and their new cellular role will emerge, soon. This review outlines the current trend, limitations, and future potential of circRNA in cancer research.

Oral cancer is one of the most common cancers in the world and India. Signaling molecules play an important role in Oral Squamous Cell Carcinoma (OSCC). PI3K and EGFR signaling molecules are known to be deregulation in most cancers including oral cancer. These are associated with oral cancer progression and drug resistance. PI3K and EGFR signalling molecules have been linked to the examined resistance developed to radiation and chemotherapy. Crucial signaling molecules that function downstream of the survival pathways, particularly at points where several of these pathways crosstalk that development oral cancer and drug resistance. The main focus of this review is to discuss the role and regulation of PI3K and EGFR in oral cancer drug resistance.

Background Cisplatin-resistant oral squamous cell carcinoma (OSCC) cells acquire stem-like characteristics and are difficult to treat. Nanog is a transcription factor and needed for maintenance of pluripotency, but its transcription-promoting role in OSCC progression and cisplatin resistance is poorly understood. Methods Here, 110 fresh human tissue specimens of various stages, including invasive (N1-3 )/chemoradiation-resistant OSCC samples, cisplatin-resistant (CisR-SCC-4/-9) OSCC cells/parental cells, photochemical ECGC, and siRNA (Nanog) were used. Results Nanog overexpression was associated with overall progression, chemoresistance, and invasion of OSCC. Nanog recruitment to c-Myc, Slug, E-cadherin, and Oct-4 gene promoter was observed. Positive correlation of Nanog protein expression with c-Myc, Slug, cyclin D1, MMP-2/-9, and Oct-4 and negative correlation with E-cadherin gene expression were found. Knockdown of Nanog and treatment of epicatechin-3-gallate reversed cisplatin resistance and diminished invasion/migration potential. Conclusion Nanog directly participated in the regulation of Slug, E-cadherin, Oct-4, and c-Myc genes, causing cisplatin resistance/recurrence of OSCC.

The expression and SNPs of innate immunity genes TLR-4/9 for bacterial infection, gingival inflammation/gingival recession (GIGR), and oral squamous cell carcinoma (OSCC) are largely unknown.235 specimens (120 OSCC cases, among which 85 cases with either Porphyromonas gingivalis, Fusobacterium nucleatum or Treponema denticola infection and GIGR) and 115 healthy controls were used to know the expression and polymorphisms (TLR-4: N1:rs10759931, N2:rs11536889, N3:rs1927911, N4:rs4986790; TLR-9: N5:rs5743836, N6:rs352140, N7:rs187084 and N8:rs352139) of TLR-4/9 by western blot, RT-PCR, and allele-specific (AS)-PCR followed by sequencing.Increased TLR-4/9 mRNA/protein expression, bacterial infection (BI) and GIGR were associated with OSCC incidence. One of the three BI and GIGR was observed in 70.83% of OSCC cases, whereas all the HC used were free from any of these three BI/GIGR. The N3: CT-genotype (Odds Ratio hereafter as O.R.=1.811, p = 0.0338), TT-genotype (O.R.=3.094, p = 0.0124), 'T'-allele (O.R.=1.821, p = 0.003), N4: AG-genotype (O.R.=2.015, p = 0.0222) and 'G'-allele (O.R.=1.86, p = 0.018) of TLR-4 as well as the N5: CC-genotype (O.R.=3.939, p = 0.0017), 'C'-allele (O.R.=1.839, p = 0.0042), N6: AA-genotype (O.R.=2.195, p = 0.0234), 'A'-allele (O.R.=1.569, p = 0.0163), N7: TC-genotype (O.R.=2.083, p = 0.0136), CC-genotype (O.R.=2.984, p = 0.003) and 'C'-allele (O.R.=1.885, p = 0.0008) of TLR-9 were associated with increased OSCC risk. Similarly, the N2:'C'-allele (O.R.=1.615, p = 0.0382), N3: TT-genotype (O.R.=2.829, p = 0.0336), 'T'-allele (O.R.=1.742, p = 0.0115), N4: AG-genotype (O.R.=2.221, p = 0.0147) and 'G'-allele (O.R.=1.890, p = 0.0238) of TLR-4 as well as the N5: CC-genotype (O.R.=2.830, p = 0.031), N6: AA-genotype (O.R.=2.6, p = 0.0122) and 'A'-allele (O.R.=1.746, p = 0.0064), N7:CC-genotype (O.R.2.706, p = 0.0111) and 'C'-allele (O.R. 1.774, p = 0.0055) of TLR-9 were correlated with GIGR and BI. TLR-4 (N1-N2-N3-N4: A-C-T-A (O.R.=2.1, p = 0.0069) and TLR-9 (N5-N6-N7-N8: T-A-C-A (O.R.=2.019, p = 0.0263); C-A-C-A (O.R.=6.0, p = 0.0084); C-A-C-G (O.R.=4.957, p = 0.0452) haplotypes were linked with OSCC vulnerability, while the TLR-4 (N1-N2-N3-N4: G-C-C-A (O.R.=0.5752, p = 0.0131) and TLR-9 (N5-N6-N7-N8: T-G-T-A (O.R.=0.5438, p = 0.0314); T-G-T-G (O.R.=0.5241, p = 0.036) haplotypes offered protection.TLR-4/9 expression, polymorphisms, and BI-induced GIGR could increase OSCC risk. This may be used in pathogenesis and oral cancer prediction.

Background Bcl-xL is an anti-apoptotic molecule, but its role in the progression and recurrent/ drug-resistant oral squamous cell carcinoma (OSCC) is poorly understood. Materials and methods A total of one hundred twenty-five human OSCC tissue specimens including twenty-nine adjacent normals (AN), sixty-nine primary tumors (PT), twenty-seven recurrent chemoradiation resistance (RCRT) samples, and oral tongue SCC derived cisplatin-resistant (CisR SCC-4/-9) cells were used, for this study. Protein/mRNA expression levels of Bcl-xL and its regulation by ERK1/2, Stat-3, p53, NFκB, AP-1 (components: c-Jun, c-Fos, and Fra-2) molecules, and cell viability were measured by immunohistochemistry, Western blot, RT-PCR, and MTT analysis. Further, the individual and synergistic effects of Fra-2 (siRNA) and nimbolide were tested in CisR SCC-4/-9 cells. Results Progressive increase of Bcl-xL expression and its transcriptional-deregulation was observed with OSCC progression and resistance. Among all the possible upstream regulators of Bcl-xL, such as ERK1/2, Stat-3, p53, AP-1, and NFκB, the TF AP-1 (r = 0.644, p = 0.0001) showed maximum association with Bcl-xL mRNA expression. Though differential expression of AP-1 components were detected in OSCC specimens, with more striking positive-correction of c-Jun (r = 0.381, p = 0.049), c-Fos (r = 0.139, p = 0.488, ns) and Fra-2 (r = 0.664, p = 0.0001) with Bcl-xL expression observed stronger in RCRT tumor subgroup. Further, knockdown of Fra-2 and the application of plant-based phytochemical nimbolide decreased Bcl-xL expression and induced apoptosis in CisR SCC-4/-9 cells. Conclusion Collectively, we have demonstrated the role of Bcl-xL and AP-1 (Fra-2), causing OSCC progression and cisplatin resistance. Targeting Bcl-xL upstream pathway along with the application of nimbolide might be beneficial in eliminating drug-resistant OSCC.

Mixed lineage kinase 3 (MLK3), a MAP3K member has been envisioned as a viable drug target in cancer, yet its detailed function and signaling is not fully elucidated. We identified that MLK3 tightly associates with an oncogene, PAK1. Mammalian PAK1 being a Ste20 (MAP4K) member, we tested whether it is an upstream regulator of MLK3. In contrast to our hypothesis, MLK3 activated PAK1 kinase activity directly, as well as in the cells. Although, MLK3 can phosphorylate PAK1 on Ser133 and Ser204 sites, PAK1S133A mutant is constitutively active, whereas, PAK1S204A is not activated by MLK3. Stable overexpression of PAK1S204A in breast cancer cells, impedes migration, invasion, and NFĸB activity. In vivo breast cancer cell tumorigenesis is significantly reduced in tumors expressing PAK1S204A mutant. These results suggest that mammalian PAK1 does not act as a MAP4K and MLK3-induced direct activation of PAK1 plays a key role in breast cancer tumorigenesis.

Loco-regional invasion is commonly found in oral squamous cell carcinoma (OSCC) and is associated with its poor survival rate. Matrix metalloproteinase-2 (MMP-2) has been implicated in OSCC progression, but its regulation is poorly understood.Here, one hundred twenty-seven different post-operated human oral cancer tissue samples were analyzed. The messenger RNA (mRNA) expression, protein expression, and MMP-2 activity and MT1-MMP, TIMP-2, and TFs (NFκB, AP1, Sp1, and Twist) were observed semi-quantitative RT-PCR, western blotting, and gelatin zymography. In addition, OSCC derived Cal-27, SCC4/9 cells, photochemical ECGC, and MAPK-pathway inhibitor PD98059 were utilized for in vitro testing and wound healing assay.s: Increased protein and activity level of MMP-2 was detected in non-invasive (NOur research suggests that the ERK1/2 driven overexpression/activation of MMP-2 was linked with the overall OSCC invasion and metastasis. Treatment of MEK inhibitor (PD98059) and ECGC diminished MMP-2 activity and thus could be exploited as a therapeutic strategy to control the invasive OSCC.

Background The cell-surface glycoprotein CD44 is an important oral cancer stem cell (OCSC) marker and plays significant role in oral squamous cell carcinoma (OSCC) aggressiveness, however, the regulation of CD44 is incompletely understood. Methods In the present study, 145 fresh human OSCC tissue specimens, including 18 adjacent normal, 42 noninvasive (N0), 53 invasive tumor samples (N1-3) and 32 chemo-radiation resistant samples (RCRT), were included. The expression of CD44 standard (CD44s) and variants (CD44v4, CD44v6); the activation of pERK1/2, GSK3β, NICD (Notch) pathways; the cell viability; and the MMP-9/-2 activity were assessed using RT-PCR, immunohistochemistry, Western blotting, MTT assay and gelatin zymography. OSCC cell lines, including parental (SCC9/SCC4) and Cisplatin-resistant (CisR-SCC9/-SCC4) cells, were used. Knock down of CD44v4/CD44v6 (by siRNA) or inactivation of MAPK/PI3K pathways using specific PD98059/LY294002 was achieved for in vitro analysis of chemoresistance and invasion/migration. Results Elevated CD44 variants were associated with overall OSCC progression, chemoresistance and invasion. Positive correlations were observed, mainly between the expression of CD44v4 and the activation of ERK1/2 causing chemoresistance, whereas CD44v6 expression and inactivation of GSK3β caused invasiveness of OSCC. Cisplatin resistant, CisR-SCC9/SCC4 cell lines showed OCSC properties. Inhibition of MEK/ERK1/2 by SMI or knock down (KD) of CD44v4 by siRNA reversed cisplatin-resistance, whereas blocking the PI3K/Akt/GSK3β pathway by SMI or KD of CD44v6 isoforms by respective siRNA diminished invasion/metastasis potential. Conclusion Collectively, our results demonstrated that CD44v4 expression is more linked with ERK1/2 activation and promote cisplatin resistance, whereas CD44v6 expression is associated primarily with PI3K/Akt/GSK3β activation and driving tumor invasion/migration.

Of late, nimbolide, a limonoid from the neem tree (Azadirachta indica) has gained increasing research attention owing to its potent antiproliferative and apoptosis-inducing effects. The present study was designed to investigate the effect of nimbolide on autophagy and the time point at which the phosphorylation status of GSK-3β and PI3K dictate the choice between autophagy and apoptosis in SCC131 and SCC4 oral cancer cells. Additionally, we analysed changes in the expression of proteins involved in autophagy and apoptosis after therapeutic intervention with nimbolide in a hamster model of oral oncogenesis. Furthermore, we also demonstrate changes in the expression of key genes involved in apoptosis and autophagy during the stepwise evolution of hamster and human OSCCs. Nimbolide-induced stereotypical changes in oral cancer cells characteristic of both apoptosis and autophagy. Time-course experiments revealed that nimbolide induces autophagy as an early event and then switches over to apoptosis. Nimbolide negatively regulates PI3K/Akt signalling with consequent increase in p-GSK-3βTyr216, the active form of GSK-3β that inhibits autophagy. Downregulation of HOTAIR, a competing endogenous RNA that sponges miR-126 may be a major contributor to the inactivation of PI3K/Akt/GSK3 signalling by nimbolide. Analysis of key markers of apoptosis and autophagy as well as p-AktSer473 during sequential progression of hamster and human OSCC revealed a gradual evolution to a pro-autophagic and antiapoptotic phenotype that could confer a survival advantage to tumors. In summary, the results of the present study provide insights into the molecular mechanisms by which nimbolide augments apoptosis by overcoming the shielding effects of cytoprotective autophagy through modulation of the phosphorylation status of Akt and GSK-3β as well as the ncRNAs miR-126 and HOTAIR. Development of phytochemicals such as nimbolide that target the complex interaction between proteins and ncRNAs that regulate the autophagy/apoptosis flux is of paramount importance in cancer prevention and therapeutics.

Oral squamous cell carcinoma (OSCC)-related deaths mainly result from invasion of the tumor cells into local cervical lymph nodes. It has been reported that progressive basement membrane loss promotes the metastatic and invasive capacities of OSCCs. Matrix metalloproteinase-9 (MMP-9) is known to play a central role in tumor progression and invasion. However, the role of MMP-9 in OSCC invasion has so far remained paradoxical and little is known about its regulation. Here, we aimed to assess MMP-9 expression regulation and its activation by glycogen synthase kinase-3β during human OSCC progression and invasion. In the present study, 178 human OSCC samples, including 118 fresh samples (18 adjacent normal, 42 noninvasive and 58 invasive tumor samples) and 60 archival human tissue microarray (TMA) tongue cancer samples, were included. mRNA expression, protein expression, MMP-9/-2 activity, protein-protein interaction and Snail, c-Myc, β-catenin and TIMP1 expression were assessed using RT-PCR, immunohistochemistry, Western blotting, co-immunoprecipitation and gelatin zymography analyses, respectively. Wnt5a and LPA mediated MMP-9 regulation was assessed in OCSCC-derived SCC-9 cells exogenously expressing GSK3β (WT) or non phosphoryable GSK3β (S9A). We observed a progressive up-regulation/activation of MMP-9 at various stages of oral tumor progression/invasion. Positive correlations were observed between MMP-9 and c-Myc expression, MMP-9 and MMP-2 activity, MMP-9 and TIMP1 expression and MMP-9 activity and TIMP1-MMP-9 interaction. In contrast, a negative correlation between phosphorylated β-catenin and MMP-9 expression was observed. Conversely, we found that in oral tongue SCC MMP-9 expression was positively correlated with inactivation of GSK3 signaling. Finally, we found that Wnt5a and LPA mediated increased MMP-9 and decreased GSK3β activities in tongue SCC-derived SCC-9 cells. MMP-9 regulation by GSK3β was confirmed by using phosphoryable/regulatory GSK3β (WT construct) and not by non-phosphoryable GSK3β (S9A construct). Collectively, our results show that MMP-9 overexpression and activation are important events occurring during OSCC progression/invasion and that this overexpression/activation is regulated by c-Myc, active MMP-2 and inactive GSK3β mediated pathways.

Oral cancer is the sixth most common cancer in the world. Failure of chemoradiation therapy is a major concern for treating oral cancer patients. The objective of this study is to determine the B cell lymphoma-2 (bcl-2) expression and its regulation by nuclear factor κB (NFκB) and activator protein 1 (AP-1) in oral cancer progression and chemoradiation resistance. In the present study, a total of 123 (n = 123) human samples were included. Briefly, 64 fresh samples were from adjacent normal (AN), primary oral tumors without treatment (PT), and tumors with resistance to chemoradiation therapy with local recurrence (RCRT). Fifty-nine samples were human tongue cancers and normal samples (TMA). Messenger RNA (mRNA) expression levels of bcl-2 and protein levels of bcl-2, NFκB, AP-1, and inactive GSK3α/β were measured by semiquantitative RT-PCR, immunohistochemistry, Western blot, and ChIP analysis. Increased bcl-2 expression was observed in PT compared to AN. The RCRT tumors showed maximum expression of bcl-2 mRNA and protein over the PT and AN groups. Bcl-2 protein and mRNA expression were positively correlated with NFκB and AP-1 expression. AP-1 expression was strongly correlated with bcl-2 in the RCRT group of tumors. Further, inactive GSK3α/β showed a positive trend with bcl-2 expression in oral tongue cancer specimens. Collectively, our results demonstrated cumulative effect of AP-1 and NFĸB for bcl-2 gene regulation in overall PT progression and chemoradiation resistance. The study provides evidence of increased bcl-2 mRNA/protein fueled by NFĸB in PT and AP-1 in RCRT. These regulations of bcl-2 by NFκB and AP-1 are important in OSCC progression and chemoradiation resistance.

The reversion-inducing cysteine-rich protein with Kazal motifs (RECK) and glycogen synthase kinase (GSK3) are novel tumor suppressors, and emerging evidence has suggested their active role in oral cancer pathogenesis. In the present study, 112 human samples, including 55 fresh samples of 14 adjacent normal tissues, 25 noninvasive oral tumors, and 18 invasive tumors, were included. The messenger RNA (mRNA) expression, protein expression, and promoter methylation of the RECK gene, as well as the expression of GSK3β, phospho/total β-catenin, and c-myc, were measured by RT-PCR, bisulphate modification-PCR, immunohistochemistry, and Western blot analysis. Additionally, ectopic expression of in/active GSK3β was performed in cell culture experiments. This study provided information on the progressive silencing of RECK gene expression at the protein and mRNA levels paralleled with promoter hypermethylation at various stages of oral tumor invasion. RECK expression and the hypermethylation of the RECK gene promoter were negatively and positively correlated with pS9GSK3β/c-myc expression, respectively. Further, a negative trend of RECK protein expression with nuclear β-catenin expression was observed. Induced expression of active GSK3β reversed the RECK silencing in SCC9 cells. Collectively, our results demonstrated that the silencing of the RECK gene, possibly regulated by the GSK3β pathway, is an important event in oral cancer invasion and this pathway could be exploited for therapeutic interventions.

Background Expression and single nucleotide polymorphisms (SNPs) of TLR4/9 and CYP1A1 genes are vital for cervical squamous cell carcinoma (CSCC) but considerably vary in different populations. Methods A total of 255-subjects from Jharkhand (130-cases, 125-controls) were utilized to obtain the expression/SNP status of TLR4/9, CYP1A1, and E6 (HPV16/18) by RT-PCR, WB, and allele-specific-PCR followed by sequencing. Results Over-expression of TLR4/9 and high infection of HPV16/18(78.5%) were found to be associated with CSCC. Among the seven SNPs(p1-p7) tested, the CT-genotype (p3:rs1927911; OR = 2.142; p = 0.004) and ‘T’-allele (p3; OR = 1.694; p = 0.0061) of TLR4; CC-genotype (p4:rs5743836; OR = 3.307; p = 0.0018), ‘C’-allele (p4; OR = 1.895; p = 0.0009), GA-genotype (p5:rs352140; OR = 2.064; p = 0.0172), AA-genotype (p5; OR = 2.602; p = 0.0021) and ‘A’-allele (p5; OR = 1.939; p = 0.0002) of TLR9; and the TC-genotype (p6:rs4646903; OR = 1.967; p = 0.0452) and GG-genotype (p7:rs1048943; OR = 2.336; p = 0.0287) and ‘G’-allele (p7; OR = 1.685; p = 0.0082) of CYP1A1 were associated with an increased-risk of CSCC. Similarly, the p3:CT-genotype (OR = 1.993; p = 0.0134); p4:CC-genotype (OR = 3.071; p = 0.0057) and ‘C’-allele (OR = 1.838; p = 0.0029); p5:AA-genotype (OR = 2.231; p = 0.0147) and ‘A’-allele (OR = 1.756; p = 0.0032); p6:TC-genotype (OR = 2.370; p = 0.02); and the p7:GG-genotype (OR = 2.255; p = 0.0488) and ‘G’-allele (OR = 1.691; p = 0.0118) showed an association with HPV16/18 infection. Conversely, TLR4 (p1-p2-p3:A-G-T; OR = 3.361; p = 0.029), TLR9 (p4-p5:C-A; OR = 1.786; p = 0.032) and CYP1A1 (p6-p7:C-G; OR = 1.783; p = 0.033) haplotypes with CSCC susceptibility was observed, whereas the TLR4 (p1-p2-p3:A-C-C; OR = 0.4675; p = 8.E-3) and TLR9 (p4-p5:T-G; OR = 0.3937; p = 0.00) haplotypes showed protection against the development of CSCC. Further, though p1:rs10759931 and p2:rs11536889 were found to be insignificant, the p3:CT-genotype, p5:GA/AA-genotype, and p7:GG-genotype were associated with elevated protein; the p4:CC-genotype and p6:TC-genotype were associated with increased mRNA compared to their respective-wild-type-groups. Conclusion The present study revealed an association between TLR4/9 and CYP1A1 polymorphisms with increased HPV16/18 infection susceptibility and CSCC risk among the women of Jharkhand state.

Background Bax, a proapoptotic protein but its regulation during oral cancer progression and resistance remains elusive. Methods A total of 127 samples including adjacent normal, primary tumor, and resistance to chemoradiation therapy (RCRT) samples from oral squamous cell carcinoma (OSCC) patients were used. The status of Bax was analyzed at DNA/mRNA/protein levels and the results were correlated with p53 and Akt expression in tissue samples/cisplatin-resistant oral tongue SCC (SCC9/SCC4-CisR) cell line. Results Frequent progressive decrease of Bax expression with infrequent promoter methylation, polymorphisms G(-248)A, and mutations was observed in OSCC progression/resistance. Furthermore, by targeting Akt pathway, induction of Bax-dependent cell death was observed and this was further enhanced with nimbolide treatment in SCC9/SCC4-CisR cells. Conclusion Hence, the Bax gene alteration and its deregulation through p53/Akt pathway are important for OSCC progression and drug resistance. Akt Inhibitor VIII and nimbolide synergistically induce Bax, and it is therefore beneficial for chemosensitizing cisplatin-resistant human OSCC.

Glycogen synthase kinase-3 (GSK-3), a serine/threonine kinase is an archetypal multifunctional moonlighting protein involved in diverse cellular processes including metabolism, insulin signaling, proliferation, differentiation, apoptosis, neuronal function and embryonic development. The two known isoforms, GSK-3α and GSK-3β that undergo activation/inactivation by post-translational, site-specific phosphorylation incorporate a vast number of substrates in their repertoire. Dysregulation of GSK-3 has been linked to diverse disease entities including cancer. The role of GSK-3 in cancer is paradoxical and enigmatic. The enzyme functions as a tumour promoter or suppressor based on the context, cell type and phosphorylation status. GSK-3 is the central hub that orchestrates signals from the Wnt/β-catenin, PI3K/PTEN/Akt/mTOR, Ras/Raf/MEK/ERK, hedgehog, Notch and TP53 pathways to elicit regulatory influences on cancer initiation, epithelial-mesenchymal transition, and resistance to therapy. As a direct target of several microRNAs, GSK-3 influences hallmark attributes of cancer, cancer stemness and treatment resistance. There is overwhelming evidence to indicate that GSK-3 is aberrantly regulated in different cancer types. Consequently, GSK-3 has emerged as a potential therapeutic target in cancer. A plethora of natural and synthetic GSK-3 modulators have been discovered and the number of patents published for GSK-3 inhibitors has also been steadily increasing in recent years. This review focuses on the intricate interactions between GSK-3 and oncogenic signalling circuits as well as the feasibility of targeting GSK-3 for the treatment of cancer.

OBJECTIVE: We inspected the relevance of CD44, ABCB1 and ADAM17 in OSCC stemness and deciphered the role of autophagy/mitophagy in regulating stemness and chemoresistance. MATERIAL AND METHODS: A retrospective analysis of CD44, ABCB1 and ADAM17 with respect to the various clinico‐pathological factors and their correlation was analysed in sixty OSCC samples. Furthermore, the stemness and chemoresistance were studied in resistant oral cancer cells using sphere formation assay, flow cytometry and florescence microscopy. The role of autophagy/mitophagy was investigated by transient transfection of siATG14, GFP‐LC3, tF‐LC3, mKeima‐Red‐Mito7 and Western blot analysis of autophagic and mitochondrial proteins. RESULTS: In OSCC, high CD44, ABCB1 and ADAM17 expressions were correlated with higher tumour grades and poor differentiation and show significant correlation in their co‐expression. In vitro and OSCC tissue double labelling confirmed that CD44(+) cells co‐expresses ABCB1 and ADAM17. Further, cisplatin (CDDP)‐resistant FaDu cells displayed stem‐like features and higher CD44, ABCB1 and ADAM17 expression. Higher autophagic flux and mitophagy were observed in resistant FaDu cells as compared to parental cells, and inhibition of autophagy led to the decrease in stemness, restoration of mitochondrial proteins and reduced expression of CD44, ABCB1 and ADAM17. CONCLUSION: The CD44(+)/ABCB1(+)/ADAM17(+) expression in OSCC is associated with stemness and chemoresistance. Further, this study highlights the involvement of mitophagy in chemoresistance and autophagic regulation of stemness in OSCC.

Reversion-inducing cysteine-rich protein with Kazal motifs (RECK), a potent inhibitor of matrix metalloproteinases (MMPs) is a common negative target of oncogenic signals and a potential therapeutic target for novel drug development. Here, we show that sequential RECKlessness stimulates angiogenesis and Notch signalling in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model, a paradigm for oral oncogenesis and chemointervention. We also report the chemotherapeutic effect of nimbolide, a limonoid from the neem tree (Azadirachta indica) based on the upregulation of RECK as well as modulation of the expression of key molecules involved in invasion and angiogenesis. We demonstrate that nimbolide upregulates RECK by targeting miR-21, and HIF-1α resulting in reduced MMP activity and blockade of VEGF and Notch signalling. Nimbolide reduced microvascular density, confirming its anti-angiogenic potential. Molecular docking analysis revealed interaction of nimbolide with HIF-1α. Additionally, we demonstrate that nimbolide upregulates RECK expression via downregulation of HIF-1α and miR-21 by overexpression and knockdown experiments in SCC4 and EAhy926 cell lines. Taken together, these findings provide compelling evidence that targeting RECK, a keystone protein that regulates mediators of invasion and angiogenesis with phytochemicals such as nimbolide may be a robust therapeutic approach to prevent oral cancer progression.

Mixed lineage kinase 3 (MLK3), a MAP3K member has been envisioned as a viable drug target in cancer, yet its detailed function and signaling is not fully elucidated. We identified that MLK3 tightly associates with an oncogene, PAK1. Mammalian PAK1 being a Ste20 (MAP4K) member, we tested whether it is an upstream regulator of MLK3. In contrast to our hypothesis, MLK3 activated PAK1 kinase activity directly, as well as in the cells. Although, MLK3 can phosphorylate PAK1 on Ser133 and Ser204 sites, PAK1S133A mutant is constitutively active, whereas, PAK1S204A is not activated by MLK3. Stable overexpression of PAK1S204A in breast cancer cells, impedes migration, invasion, and NFĸB activity. In vivo breast cancer cell tumorigenesis is significantly reduced in tumors expressing PAK1S204A mutant. These results suggest that mammalian PAK1 does not act as a MAP4K and MLK3-induced direct activation of PAK1 plays a key role in breast cancer tumorigenesis.

Purpose: Cluster of differentiation 44 (CD44) is a cell-surface glycoprotein and plays role in the progression and severity of oral squamous cell carcinoma (OSCC). Here we report differential function of CD44 variants in OSCC progression. Materials and methods: The expression of CD44 standard (CD44s) and variants (CD44v4, CD44v6); the activation of signaling pathways (MAPK, PI3K); the cell viability; and the MMP-9/-2 activity were assessed using RT-PCR, immunohistochemistry, Western blotting, MTT assay and gelatin zymography. These experiments were carried out using fresh human OSCC tissue specimens, including adjacent normal, noninvasive (N0), invasive tumor samples (N1-3) and chemo-radiation resistant tumor samples (RCRT). We also used OSCC cell lines, including parental (SCC9/SCC4) and Cisplatin-resistant (CisR-SCC9/-SCC4) to confirm our observation with human tissues. Knock down of CD44 variants or inactivation of MAPK/PI3K pathways was achieved for in vitro analysis in OSCC cells. Summary: Differential expressions of CD44 variants (v4and v6) were associated with overall oral cancer aggressiveness. CD44v4 expression was positively correlated with the activation of MAPK pathway causing chemoresistance. Conversely, CD44v6 expression and activation of PI3K-Akt caused invasiveness of OSCC. Finally, an overlapping role of two major signal transduction pathways such as MAPK and PI3K, that impinge on the variants/ isoforms expressions of a single gene i.e. CD44 that leads to the OSCC aggressiveness. Conclusion: Collectively, these results established that CD44 variants (v4and v6) expression driven by MAPK/PI3K are associated with the overall progression, drug-resistance, invasion, and stemness characteristics leading to the aggressiveness of OSCC. Hence targeting these pathways may be exploited for treating OSCC. Keywords: OSCC, CD44s, CD44v4/6, MAPK, PI3K, Notch, Chemoresistance, Invasion/migration, stemness, aggressiveness of OSCC. Note: This abstract was not presented at the meeting. Citation Format: Tanushree Kashyap, Siddavaram Nagini, Ajay Rana, Rajakishore Mishra. Differential expression of CD44 variants drive the progression, invasion, drug-resistance and stemness characteristics in human oral squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1165.

Identifying agents that activate nuclear factor erythroid-2 related factor-2 (Nrf2), a key regulator of various cytoprotective antioxidant, and detoxifying enzymes has evolved as a promising strategy for cancer chemoprevention. In the present study, we investigated the effect of dietary supplementation of structurally diverse phytochemicals- astaxanthin, blueberry, chlorophyllin, ellagic acid, and theaphenon-E on Nrf2 signaling, and xenobiotic-metabolizing and antioxidant enzymes in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model. We observed that these phytochemicals induce nuclear accumulation of Nrf2 while downregulating its negative regulator, Keap-1. This was associated with reduced expression of CYP1A1 and CYP1B1, the cytochrome P450 isoforms involved in the activation of DMBA, and the oxidative stress marker 8-hydroxy-2′-deoxyguanosine coupled with upregulation of the phase II detoxification enzymes glutathione S-transferases and NAD(P)H:quinone oxidoreductase 1 and the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. In addition, these dietary phytochemicals also enhanced the DNA repair enzymes 8-oxoguanine glycosylase 1 (OGG1), xeroderma pigmentosum D (XPD), xeroderma pigmentosum G (XPG), and x-ray repair cross complementing group 1 (XRCC1). Our data provide substantial evidence that the dietary phytochemicals inhibit the development of HBP carcinomas through the activation of Nrf2/Keap-1 signaling and by upregulating cytoprotective enzymes. The extent of the chemopreventive effects of the phytochemicals was in the order: chlorophyllin > blueberry > ellagic acid > astaxanthin > theaphenon-E. Thus these dietary phytochemicals that function as potent activators of Nrf2 and its orchestrated response are novel candidates for cancer chemoprevention.

The adamalysins, which include the ADAMs and ADAMTSs, are multidomain, multifunctional proteins of the metzincin superfamily of zinc-dependent metalloproteinases that play a key role in extracellular matrix remodeling and regulation of the tissue microenvironment. While ADAMs are mostly membrane-anchored proteinases, the ADAMTSs are secreted proteinases and/or adhesion molecules. A major function of the ADAMs is ectodomain shedding of membrane-bound growth factors, receptors, cytokines, chemokines, and proteoglycans. The adamalysins are also involved in a multitude of biological processes including fertilization, organogenesis, hemostasis, cell adhesion, intracellular signaling, angiogenesis, and ECM assembly and turnover. These metalloproteinases exert both promoting and inhibitory effects on tumorigenesis and serve as biomarkers of cancer progression and prognosis. Dysregulated expression of adamalysins leads to acquisition of cancer hallmarks such as increased cell proliferation, apoptosis evasion, migration, neovascularization, invasion, and metastasis. In addition, aberrant expression of these proteases also results in drug resistance. Of late, the adamalysins have emerged as potential molecular targets for cancer therapeutics. This chapter summarizes current knowledge on the different types of ADAMs and ADAMTSs, their general structure, functions, role in cancer progression, and acquisition of major cancer hallmarks as well as their potential as diagnostic and prognostic aids and therapeutic targets based on available literature.

Glycogen synthase kinase-3β (GSK-3β), a serine/threonine kinase is frequently inactivated by the oncogenic signalling kinases PI3K/Akt and MAPK/ERK in diverse malignancies. The present study was designed to investigate GSK-3β signalling circuits in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model and the therapeutic potential of the neem limonoid nimbolide. Inactivation of GSK-3β by phosphorylation at serine 9 and activation of PI3K/Akt, MAPK/ERK and β-catenin was associated with increased cell proliferation and apoptosis evasion during stepwise evolution of HBP carcinomas. Administration of nimbolide inhibited PI3K/Akt signalling with consequent activation of GSK-3β thereby inducing trafficking of β-catenin away from the nucleus and enhancing the expression of miR-126 and let-7. Molecular docking studies confirmed interaction of nimbolide with PI3K, Akt, ERK and GSK-3β. Furthermore, nimbolide attenuated cell proliferation and induced apoptosis as evidenced by increased p-cyclin D1Thr286 and pro-apoptotic proteins. The present study has unravelled aberrant phosphorylation as a key determinant for oncogenic signalling and acquisition of cancer hallmarks in the HBP model. The study has also provided mechanistic insights into the chemotherapeutic potential of nimbolide that may be a useful addition to the armamentarium of natural compounds targeting PI3K for oral cancer treatment.

Nuclear protein peptidyl-prolyl isomerase Pin1-mediated prolyl isomerization is an essential and novel regulatory mechanism for protein phosphorylation. Therefore, tight regulation of Pin1 localization and catalytic activity is crucial for its normal nuclear functions. Pin1 is commonly dysregulated during oncogenesis and likely contributes to these pathologies; however, the mechanism(s) by which Pin1 catalytic activity and nuclear localization are increased is unknown. Here we demonstrate that mixed-lineage kinase 3 (MLK3), a MAP3K family member, phosphorylates Pin1 on a Ser138 site to increase its catalytic activity and nuclear translocation. This phosphorylation event drives the cell cycle and promotes cyclin D1 stability and centrosome amplification. Notably, Pin1 pSer138 is significantly up-regulated in breast tumors and is localized in the nucleus. These findings collectively suggest that the MLK3-Pin1 signaling cascade plays a critical role in regulating the cell cycle, centrosome numbers, and oncogenesis.

Parkinson's disease (PD) is a common neurodegenerative movement disorder characterized by extensive degeneration of dopaminergic neurons in the nigrostriatal system. Neurochemical and neuropathological analyses clearly indicate that oxidative stress, mitochondrial dysfunction, neuroinflammation and impairment of the ubiquitin-proteasome system (UPS) are major mechanisms of dopaminergic degeneration. Evidence from experimental models and postmortem PD brain tissues demonstrates that apoptotic cell death is the common final pathway responsible for selective and irreversible loss of nigral dopaminergic neurons. Epidemiological studies imply both environmental neurotoxicants and genetic predisposition are risk factors for PD, though the cellular mechanisms underlying selective dopaminergic degeneration remain unclear. Recent progress in signal transduction research is beginning to unravel the complex mechanisms governing dopaminergic degeneration. During the 12th International Neurotoxicology meeting, discussion at one symposium focused on several key signaling pathways of dopaminergic degeneration. This review summarizes two novel signaling pathways of nigral dopaminergic degeneration that have been elucidated using neurotoxicity models of PD. Dr. Anumantha Kanthasamy described a cell death pathway involving the novel protein kinase C delta isoform (PKCdelta) in oxidative stress-induced apoptotic cell death in experimental models of PD. Dr. Ajay Rana presented his recent work on the role of mixed lineage kinase-3 (MLK3) in neuroinflammatory processes in neurotoxic cell death. Collectively, PKCdelta and MLK3 signaling pathways provide new understanding of neurodegenerative processes in PD, and further exploration of these pathways may translate into effective neuroprotective drugs for the treatment of PD.

Purpose: Matrix metalloproteinase-9 (MMP-9), a Zn-dependent endopeptidase is known to play a central role in oral cancer pathogenesis. Recently we observed differential function of MMP-9 and reversion-inducing cysteine-rich protein with Kazal motifs (RECK) respectively in OSCC invasion. We hypothesize that the downregulation of MMP-9 via RECK promotes human oral cancer progression and invasion. Experimental procedure: The mRNA expression, protein expression and activity of MMP-9/2, expression of transcription factors like Snail, c-Myc, β-catenin and protein-protein interaction of TIMP1/RECK with MMP9 and promoter methylation of RECK gene were assessed by using RT-PCR, immunohistochemistry (IHC), Western blotting, co-immunoprecipitation, gelatin zymography, and bisulphate modification-PCR analyses. Wnt5a and LPA mediated MMP-9 regulation as well as the MMP-9 regulation by the exogenously expression of RECK, GSK3β (WT) or non phosphoryable active GSK3β (S9A) was also performed in oral tongue SCC derived SCC-9 cells. Summary: We observed up-regulation/activation of MMP-9 was associated with decreased expression of RECK and progression and invasion of OSCC. MMP-9 expression/ activity was positively correlated with inactivation of GSK3β signaling. Conversely, a link between inactivation of GSK3 signaling and the progressive silencing of RECK gene through promoter hypermethylation was observed. Finally, Wnt5a and LPA mediated increased MMP-9 and decreased RECK expressions were observed. Conclusion: Taken together, these results demonstrated the influence of a novel signaling axis GSK3β-RECK-MMP-9 to drive OSCC progression and invasion. Thus, targeting this pathway may be exploited for treating OSCC. Citation Format: Kamdeo Kumar Pramanik, Basabi Rana, Ajay Rana, Rajakishore Mishra. Expression and regulation of MMP9 and RECK in human oral squamous cell carcinoma progression and invasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 103.

Mixed Lineage Kinase-3, also known as MAP3K11 is a member of a larger family of MAP3Ks, called MLKs. MLK3 has been reported to play an important role in pro-apoptotic signaling, however its role in tumorigenesis is still not fully elucidated. Previously, we reported that MLK3 is down regulated by estrogen and HER2 amplification and this down regulation provided a survival advantage to ER+ and HER2+ breast cancer cells. To further understand the role of MLK3 signaling in breast cancer pathogenesis, we aimed to identify the upstream kinase(s) that might regulate MLK3 activity and perhaps tumorigenesis. Based on available information from yeast, where Ste20 members are upstream of Ste11 (i.e. MAP3K), we hypothesized that mammalian homologue of Ste20, PAK1 could be upstream of MLK3. PAK1 kinase has been reported to be a major oncogene in many cancers, including breast cancer. Our results were however, counterintuitive to our hypothesis. We observed that instead, MLK3 was able to associate, and activate PAK1 Kinase activity. These results suggested that perhaps MLK3 is either upstream or parallel to PAK1 in the mammalian signaling network. We also observed that PAK1 was phosphorylated by MLK3 on Ser133 and Ser204 sites. Interestingly, Alanine substitution of S133 site constitutively activated PAK1 kinase activity, whereas Alanine substitution of the S204 site completely blocked MLK3-induced PAK1 activation. Constitutive active MLK3 was not able to phosphorylate and activate double mutant PAK1 S133A, S204A in vitro or in HEK293 cells, clearly indicated that PAK1 S204 site is important for MLK3-induced PAK1 activation. Since PAK1 is an oncogene in breast cancer, we determined the biological effect of S204 phosphorylation on breast cancer progression. Stable breast cancer cell line, MDA-MB-468, expressing PAK1 S204A, inhibited migration, invasion and showed significantly smaller tumors, compared to WT PAK1-expressing cells. Taken together, our results suggest that MLK3-induced modulation of PAK1 activity plays a major role in breast cancer tumorigenesis. First two authors are equally contributed Citation Format: Subhasis Das, Rakesh Sathish Nair, Rajakishore Mishra, Tanmoy Bhowmik, Basabi Rana, Ajay Rana. When MLK3 meets PAK1: Its implication in breast cancer tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2390.

Estrogen stimulates growth and inhibits apoptosis of breast cancer cells via genomic and non-genomic actions. However, the detailed mechanism by which estrogen inhibits the pro-apoptotic pathways that might impede the normal homeostasis and action of chemotherapeutic drugs in breast cancer cells is not well understood. Here, we report a negative regulation of a pro-apoptotic kinase, Mixed Lineage Kinase 3 (MLK3) by 17β-estradiol (E2) that hinders cytotoxic drug-induced cell death in estrogen receptor positive (ER+) breast cancer cells. MLK3 kinase activities were significantly higher in estrogen receptor negative (ER−), progesterone receptor negative (PR−) primary human breast tumors, suggesting that E2 might have a negative role in regulating MLK3 kinase activity. The kinase activities of MLK3 and its downstream target, JNK were rapidly inhibited by E2 in ER+ but not in ER− breast cancer cells. The inhibition of MLK3 kinase activity by E2 was mediated via activation of protein kinase B (PKB/AKT) because specific knockdown of AKT1/2 prevented the E2-induced inhibition of MLK3. Furthermore, E2-induced inhibition of MLK3 kinase activity involved a direct phosphorylation of MLK3 at Ser 674 site by AKT, which resulted in an attenuation of the pro-apoptotic function of MLK3. In addition, a pan-MLK inhibitor (CEP-11004) significantly attenuated Taxol-induced cell death, which was further synergized by E2. Thus, our data suggest that E2 negatively regulates the pro-apoptotic function of MLK3 during breast cancer pathogenesis and therefore MLK3 and other MLK family members might play an important role in cytotoxic drug-induced cell death in ER+ breast cancer cells.

Mixed lineage kinase 3 (MLK3) is a mitogen-activated protein kinase kinase kinase that is activated by tumor necrosis factor-alpha (TNF-alpha) and specifically activates c-Jun N-terminal kinase (JNK) on TNF-alpha stimulation. The mechanism by which TNF-alpha activates MLK3 is still not known. TNF receptor-associated factors (TRAFs) are adapter molecules that are recruited to cytoplasmic end of TNF receptor and mediate the downstream signaling, including activation of JNK. Here, we report that MLK3 associates with TRAF2, TRAF5 and TRAF6; however only TRAF2 can significantly induce the kinase activity of MLK3. The interaction domain of TRAF2 maps to the TRAF domain and for MLK3 to its C-terminal half (amino acids 511-847). Endogenous TRAF2 and MLK3 associate with each other in response to TNF-alpha treatment in a time-dependent manner. The association between MLK3 and TRAF2 mediates MLK3 activation and competition with the TRAF2 deletion mutant that binds to MLK3 attenuates MLK3 kinase activity in a dose-dependent manner, on TNF-alpha treatment. Furthermore the downstream target of MLK3, JNK was activated by TNF-alpha in a TRAF2-dependent manner. Hence, our data show that the direct interaction between TRAF2 and MLK3 is required for TNF-alpha-induced activation of MLK3 and its downstream target, JNK.

Cyclin Dependent Kinase 4 (Cdk4) is known to be an oncogene and is involved in various cancers. It is overexpressed either by genomic amplification or by c-myc dependent manner. Our preliminary results indicate high expression of protein and mRNA as well as absence of genomic amplification in early oral cancer development. One transcription factor (TF) binding site has been detected from −281 to −298 by using DNase I foot printing and confirmed by electrophoretic mobility shift assay. This is a novel DNA sequence. The recruitment of this new TF as well as the earlier reported c-myc was analyzed in various stage of oral cancer development. The binding activity of the new TF is present in normal tissues and observed more in initial stage samples whereas c-myc expression was absent in normal and more in higher stage of oral cancer development. On the basis of these findings we propose the new TF to be a possible CdK4 Regulating Factor (KRF). This might maintain the basal level transcription in normal and activates Cdk4 transcription in the initial stage, where as the same role is carried by c-myc in higher stage of chewing tobacco mediated oral cancer development.

BACKGROUND The Jak/Stat signaling pathway transmits signals from many cytokines and growth factor receptors to target genes in the nucleus. Constitutive activation of Stat-3 recently has been observed in many tumor cells, and dysregulation of the Stat signaling pathway has been proposed to be implicated in malignant transformation. In the current study for the first time to the authors's knowledge, the expression of STAT-3 was analyzed in various stages and sites of squamous cell carcinoma of the head and neck (HNSCC). METHODS Tissue samples from 90 patients of tobacco chewing-mediated HNSCC representing various stages, sites, and differentiation states were selected for studying STAT-3 protein and RNA expression. In vivo localization of STAT-3 was studied by immunohistochemistry of paraffin embedded sections. The presence of STAT-3 and its phophorylated and activated form pSTAT-3 was checked by Western blotting. mRNA expression was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). Apoptosis analysis was conducted by in situ ENA nick end labeling assay and hematoxylin and eosin staining. RESULTS Overall, 58.9% of HNSCC tumors showed very high Stat-3 protein accumulation, and 23.3% showed intermediate accumulation whereas 17.8% of HNSCC tumors were negative for Stat-3. No Stat-3 was detected in normal samples, and only one of eight premalignant lesions showed intermediate Stat-3 accumulation. On immunoblotting, very high protein accumulation was detected in T1 and T2 classification, moderate in T3 and T4 (P = 0.033, chi-square test), whereas no Stat-3 was detected in normal samples. Similar trend also was found in Stat-3 mRNA expression by RT-PCR analysis which was high in T1 and T2 (early stages), moderate in T3 and T4 (late stages), and no expression in normal samples. The mean apoptotic indices were 1.75, 1.88, and 1.66 for normal, premalignant lesions, and HNSCC cases, respectively. CONCLUSIONS Stat-3 activation is an early event in head and neck carcinogenesis though its role in blocking the apoptosis in vivo in solid tumors was not observed. Cancer 2002;94:2393–400. © 2002 American Cancer Society. DOI 10.1002/cncr.10499

Mixed lineage kinases (MLKs) are members of the mitogen-activated protein kinase kinase kinase (MAP3K) family and are reported to activate MAP kinase pathways. There have been at least 9 members of the MLK family identified to date, although the physiological functions of all the family members are yet unknown. However, MLKs in general have been implicated in neurodegenerative diseases, including Parkinson and Alzheimer diseases. Recent reports suggest that some of the MLK members could play a role in cancer via modulating cell migration, invasion, cell cycle, and apoptosis. This review article will first describe the biology of MLK members and then discuss the current progress that relates to their functions in cancer.

Oral cancer is a growth-related disorder, and cyclins are the prime regulators of cell division. Cyclins are associated with the pathogenesis of oral cancer and are considered valuable biomarkers for diagnosis and prognosis. These important molecules are regulated in many ways to achieve a gain in function and are involved in promoting neoplastic growth. While the causes of most cyclin overexpression are varied, these cyclins may be induced by buccal mucosal insult mainly with carcinogens that alter various pathways propelling oral cancer. Substantial experimental evidences support a link between oncogenic signaling pathways and the deregulation of cyclins in oral cancer. This review focuses on the mechanisms by which cyclins are regulated and promote oral oncogenesis.

Oral squamous cell carcinoma is a major cause of morbidity and mortality worldwide. Current experimental evidence shows that most important risk factors for oral cancer include tobacco use and excessive alcohol consumption and less well-defined risks include viral infection and a diet deficient in antioxidants. The positive correlation between various risk/etiologic factors of oral cancer and the activation of various transcription factors (TFs) has been reported in the literature. Although initially, TFs were considered to be very difficult targets for use in clinical treatment, recent technological advances have provided the ability to control these factors of cancer progression. This review focuses on the role of oncogenic transcription factors in oral cancer, their modes of activation through various biological pathways, the promises and pitfalls in viewing them as potent oncotargets, the way they can be controlled based on the current understanding, and the future research to be done in this area.

Chlorophyllin, a water soluble semi-synthetic food-grade derivative is reported to exhibit a wide range of beneficial health effects. We investigated the effect of chlorophyllin supplementation on Wnt/β-catenin and vascular endothelial growth factor (VEGF) signaling in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model. Hamsters were divided into 4 groups. The right buccal pouches of group 1 and 2 hamsters were painted with 0.5 % DMBA for 14 weeks. Group 2 animals received in addition chlorophyllin (4 mg/kg bw) in the diet. Group 3 animals received chlorophyllin alone and group 4 animals served as control. mRNA and protein expression of components of Wnt, VEGF, and PI3K/Akt signaling pathways were analyzed by RT-PCR and Western blot analysis. Dietary chlorophyllin administration suppressed the development of HBP carcinomas by altering the expression of several components of the Wnt/β-catenin signaling pathway. This was associated with inhibition of angiogenesis as evidenced by decreased expression of the proangiogenic factors HIF-1α, VEGF, and VEGFR2. Chlorophyllin administration also downregulated the expression of histone deacetylases involved in epigenetic regulation of tumor angiogenesis. Dietary chlorophyllin that abrogates Wnt/β-catenin and VEGF signaling by targeting a multitude of key signaling molecules is an attractive candidate for preventing tumor progression.

Oral cancer is the sixth most common form of cancer worldwide, and the majority of cases occur in India and Southeast Asia. Its major risk factors in the western world include smoking and drinking alcohol, whereas in Asia, it is primarily caused by tobacco/areca nut/betel leaf chewing and/or human papillomavirus (HPV) infections. Little is known about this type of cancer despite recent advances in cancer biology. The generally asymptomatic nature of the early oral lesions causes them to remain undetected in many cases. Thus, the disease progresses substantially before the patients seek treatment and is a major contributing factor to the severity of this disease. Therefore, there is a great need to create awareness for its prevention and early diagnosis. The application of advanced molecular biological and biochemical methodologies to elucidate its biomarkers may aid in early detection; however, much more work must be done for this information to be effectively applied in the clinical setting. This review focuses on the need for systematic diagnoses in the early detection of oral cancer using molecular and biochemical approaches, thereby reducing the number of advanced cases in the chewing tobacco-dominated oral cancer population.

Viruses of the Paramyxoviridae family bind to their host cells by using hemagglutinin-neuraminidase (HN), which enhances fusion protein (F)-mediated membrane fusion. Although respiratory syncytial virus and parainfluenza virus 5 of this family are suggested to trigger host cell signaling during infection, the virus-induced intracellular signals dictating virus-cell fusion await elucidation. Using an F- or HN-F-containing reconstituted envelope of Sendai virus, another paramyxovirus, we revealed the role and regulation of AKT1 and Raf/MEK/ERK cascades during viral fusion with liver cells. Our observation that extracellular signal-regulated kinase (ERK) activation promotes viral fusion via ezrin-mediated cytoskeletal rearrangements, whereas AKT1 attenuates fusion by promoting phosphorylation of F protein, indicates a counteractive regulation of viral fusion by reciprocal activation of AKT1 and mitogen-activated protein kinase (MAPK) cascades, establishing a novel conceptual framework for a therapeutic strategy.

Proto-oncogene cyclin D1 is a G1 phase specific cell cycle regulator and known for its role in various cancers. The aim of the study was to understand oral cancer progression by observing the mRNA and protein expression of cyclin D1.Different oral tissue samples were selected as a model to study oral cancer progression. Those include healthy oral mucosa, premalignant lesions (Leukoplakia, Erythroplakia, Oral SubMucous Fibrosis) and oral cancer (OSCC) samples. Cyclin D1 mRNA and protein expression were detected by slot-blot and by immunohistochemical methods, respectively.Premalignant lesions (PML) showed average 3-fold increase in the mRNA expression than normal oral mucosa (p = 0.001) whereas only 1.3-fold increase in mRNA has been observed in OSCC samples over the PML. On the other hand OSCC showed average 4-fold increase in mRNA expression than normal oral mucosa (p0.001). Cyclin D1 protein accumulation has been observed in 31.3% (16/51) of the OSCC samples whereas the normal oral mucosa and the PML showed no immunoreactivity. Oral cancer samples showing positive cyclin D1 immunoreactivity has increased from 15.0% (3/20) well differentiated SCC to 31.2% (5/16) moderately differentiated SCC to 53.3% (8/15) poorly differentiated SCC, found statistically significant (p = 0.05).By observing the expression of cyclin D1 in different stages, we have noticed two major transitions that occur in normal oral mucosa that leads to oral cancer. The first transitional event transforms the normal oral mucosa to PML whereas the second transition drives the PML to OSCC. These findings give evidence that the first transition induces cyclin D1 mRNA with no detectable cyclin D1 protein. The induction of mRNA is maintained with increased cyclin D1 protein accumulation in the second transition.

Mixed lineage kinase 3 (MLK3) is a mitogen-activated protein kinase kinase kinase member that activates the c-Jun N-terminal kinase (JNK) pathway. Aberrant activation of MLK3 has been implicated in neurodegenerative diseases. Similarly, glycogen synthase kinase (GSK)-3beta has also been shown to activate JNK and contribute to neuronal apoptosis. Here, we show a functional interaction between MLK3 and GSK-3beta during nerve growth factor (NGF) withdrawal-induced cell death in PC-12 cells. The protein kinase activities of GSK-3beta, MLK3, and JNK were increased upon NGF withdrawal, which paralleled increased cell death in NGF-deprived PC-12 cells. NGF withdrawal-induced cell death and MLK3 activation were blocked by a GSK-3beta-selective inhibitor, kenpaullone. However, the MLK family inhibitor, CEP-11004, although preventing PC-12 cell death, failed to inhibit GSK-3beta activation, indicating that induction of GSK-3beta lies upstream of MLK3. In GSK-3beta-deficient murine embryonic fibroblasts, ultraviolet light was unable to activate MLK3 kinase activity, a defect that was restored upon ectopic expression of GSK-3beta. The activation of MLK3 by GSK-3beta occurred via phosphorylation of MLK3 on two amino acid residues, Ser(789) and Ser(793), that are located within the C-terminal regulatory domain of MLK3. Furthermore, the cell death induced by GSK-3beta was mediated by MLK3 in a manner dependent on its phosphorylation of the specific residues within the C-terminal domain by GSK-3beta. Taken together, our data provide a direct link between GSK-3beta and MLK3 activation in a neuronal cell death pathway and identify MLK3 as a direct downstream target of GSK-3beta. Inhibition of GSK-3 is thus a potential therapeutic strategy for neurodegenerative diseases caused by trophic factor deprivation.

Pancreatic adenocarcinoma (PDA) remains a most deadly malignancy, with less than 5% survival over 5-year. The treatment of PDA is limited due to lack of multiple drug options, however, Gemcitabine which is widely used for PDA, finally develops resistance. Therefore, there is an urgent need to identify new pathways that can alternatively be targeted in PDA. Here we report a novel pathway that promotes oncogenic potential of Gli1, an effector of hedgehog pathway (Hh). We recently reported that MLK3 phosphorylates Pin1 on Ser138 site and increases its catalytic activity and nuclear translocation. In order to identify targets of nuclear p-Pin1, we performed cancer specific gene expression profiling and found 13-fold up-regulation of Gli1 transcript, suggesting MLK3-Pin1-Gli1 axis could activate Hh pathway. Indeed we observed that all three proteins were overexpressed in pancreatic cancer cell lines (Panc-1, MiaPaca2, AsPC-I) compared to epithelial (HPDE) cells. Most importantly, MLK3, pMLK3, Pin1 and Gli1 were overexpressed in human pancreatic cancer tissues, compared to normal adjacent tissues. Expression of Pin1 and Gli1 was also higher in tumors from PDA mouse model (KPC mouse). Interestingly, MLK3 was able to directly phosphorylate Gli1 on specific residues and the transcriptional activity of Gli1 was synergistically regulated by Pin1 and MLK3 together, which was partially blocked by MLK3 pan-inhibitor, CEP-1347. CEP-1347 also down-regulated the expression of sonic hedgehog (Shh) in Panc-1 cells suggesting that MLK3 regulates Gli1 signaling at transcriptional and post-translational levels. These results prompted us to identify the ligand(s) that could activate this axis in PDA. Quite interestingly, while doing cytokine/chemokine profiling, specifically regulated by MLK3, we observed about 7-8 folds up regulation of CXCL5 in the liver of WT mice compared to MLK3 KO mice. CXCL5 up regulation was also found in the pancreas of the WT mice. Furthermore, the MLK3 was activated by CXCL5 in pancreatic cancer cell line and MLK3 kinase activities also directly correlated with the reported expression of CXCL5 in different pancreatic cell lines. In conclusion, our findings suggest that pathological activation of MLK3-Pin1 axis by CXCL5, could promote survival of pancreatic cancer cells via Hh pathway activation. Thus targeting CXCL5-MLK3-Pin1-Gli1 axis might abrogate pancreatic cancer cell growth. This work is supported by VA Grant #: BX000312 (AR) and BX000571 (BR). Citation Format: Navin Viswakarma, Gautam Sondarva, Rajakishore Mishra, Rakesh Sathish Nair, Subhasis Das, Basabi Rana, Ajay Rana. Regulation of hedgehog signaling by Mixed Lineage Kinase 3 (MAP3K11) in pancreatic cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2203. doi:10.1158/1538-7445.AM2015-2203

The frequency of p73 mutation is low in hematologic malignancies as well as solid tumors. In the present study, we scanned for mutations in the exons 4, 5, 6, and 7 of p73, as well as methylation of the CpG island in the untranslated region of exon 1, in 100 de novo AML patients. Four patients showed mutation in exon 5 and one in exon 6, and none of the patients showed mutation in exons 4 and 7. None of the patients showed p73 gene methylation. The expression level of p73 mRNA was also examined in 40 AML samples using reverse transcriptase-polymerase chain reaction. Only six AML patients showed p73 mRNA expression, as analyzed by RT-PCR analysis. However, p73 over-expression in 30% of patients was demonstrated by immunocytochemistry and Western blot analysis. Further, mutation of p73 has been correlated with p73 mRNA and p73 protein status. The results show the presence of over-expressed p73 mRNA and protein in the samples with mutated p73 gene. Thus, it is presumed that mutation of p73 might lead to production of defective p73 protein and p73 mRNA, and this might have a role in the process of leukemogenesis of AML. This report is the first demonstrating the presence of mutations in p73 gene in acute myelogenous leukemia.