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We aimed to understand the crosstalk between mismatch repair (MMR) and FA-BRCA pathway in primary bladder carcinoma (BlCa) samples as well as in chemotolerant cell line. We analysed the genetic alterations of MLH1 and MSH2 (MMR-related genes) and after that we correlated it with the nuclear translocation of FANCD2 protein. Next, we evaluated this crosstalk in T24 BlCa cell line in response to doxorubicin treatment. In primary BlCa tumors, infrequent genetic deletion (17–20%) but frequent promoter methylation (28–55%) of MLH1 and MSH2 was observed, where MLH1 was significantly (p < 0.05) more methylated among the early staged samples (NMIBC). However, MSH2 was significantly more altered among the NMIBC samples, signifying the importance of MMR pathway during the early pathogenesis of the disease. Furthermore, BlCa samples with underexpressed MLH1/MSH2 protein possessed cytoplasmic FANCD2 protein; encouraging that inefficiency of MMR proteins might restrict FANCD2 nuclear translocation. Next, we analysed publicly available data in GEO2R tool where we observed that in response to chemotherapeutic drugs, expression of MLH1, MSH2 and FANCD2 were diminishing. Validating this result in doxorubicin tolerant T24 cells, we found that expression of MLH1 and MSH2 was gradually decreased with increasing dose of doxorubicin. Interestingly, FANCD2 mono-ubiquitination (L-form) was also reduced in chemotolerant T24 cells. The crosstalk between MMR and FA-BRCA pathway was substantiated in the primary BlCa tumors. Further, in response to doxorubicin, this crosstalk was found to be hampered due to under-expression of MLH1 and MSH2 gene, thereby rendering chemotolerance. [ABSTRACT FROM AUTHOR]

Head and neck squamous cell carcinoma (HNSCC) is the 6th most frequent cancer worldwide, and the role of NOTCH1 pathway during development of HNSCC is debatable. Here, we have made an attempt to evaluate the NOTCH1 pathway status in HNSCC cell lines from different anatomical subsites. At first, mRNA expression status of NOTCH1 pathway associated genes (NOTCH1/JAG1/JAG2/HES1/HEY1/CD44/FBXW7/HIF1α/VEGF) was analysed in two HNSCC cell lines: FaDu (hypopharyngeal carcinoma) and SCC9 (tongue carcinoma) and was compared with publicly available database. Then, molecular profiling (RNA/protein) of the genes and cell cycle phase distribution analysis were done after DAPT (γ-secretase inhibitor) administration at different concentrations on the cell lines to see the differential effect, if any. High NOTCH1 pathway activation was noted in FaDu cell line than the SCC9. In cytotoxicity assay with DAPT, FaDu showed more sensitivity than SCC9. Therefore, gradual decline of the expression of NOTCH1 pathway associated genes was noted in FaDu with the increasing DAPT concentrations, leading to high S/G2-M arrest of the cell population. Contrastingly, SCC9 showed significant reduced expression of the genes at higher concentration of DAPT with comparatively low S/G2-M arrest of the cell population. The study demonstrates distinct NOTCH1 pathway signature in the HNSCC cell lines of specific sub-sites of head and neck. [ABSTRACT FROM AUTHOR]

The activation of PIK3CA in bladder carcinoma (BlCa) with its recurrent mutations in exon 9 and 20 were well reported. But the association of arsenic on the activation of the pathway is not well elucidated. Therefore, we aimed to analyse the effect of arsenic on the genetic (copy number variation/mutation) and expression profiles of PIK3CA in primary BlCa samples. Infrequent amplification (16%) of the PIK3CA locus was observed, with higher frequency among the arsenic-high (AsH) than arsenic-low (AsL) samples. Frequent (54%) tumour-specific mutations in exon 9 and 20 of PIK3CA were observed in the BlCa samples with prevalent (47%) C>T transition mutations. Exon 9 and 20 harboured 48% and 73% of the total mutations, respectively, with 37% in E542K/E545K and 25% of the mutation in H1047Y/R. Though mutation frequency in AsH and AsL was found to be comparable, we observed some arsenic-specific mutation at c.1633G>A, c.1634A>C (E545K) and c.2985C>T and c.3130G>T mutations, as well as prevalent transverse mutations of A>C and G>T in AsH group. Furthermore, 73% of the BlCa samples showed overexpression (mRNA/protein) of PIK3CA with genetic alterations (amplification/mutation), significantly (P = 0.01) higher in AsH group. However, 36% of the samples showed overexpressed PIK3CA, independent of mutation or amplification, signifying a transcriptional upregulation of PIK3CA gene. Therefore, the expression status of NFκB, a transcription factor of PIK3CA, was assessed and found to be significantly correlated with the overexpression of PIK3CA (mRNA/protein) in AsH group. Similarly, the expression pattern of pAKT1 (Thr 308) was also found to be significantly correlated with PIK3CA overexpression. Finally, AsH patients with the overexpression of PIK3CA or NFκB had the worst overall survival, signifying a strong impact of arsenic on this pathway and outcome of the patients. Thus, our study showed that the arsenic-associated differential molecular profile of PIK3CA/AKT1/NFkB in BlCa has an important role in the molecular pathogenesis of the disease. [ABSTRACT FROM AUTHOR]

Purpose: The study was aimed to understand the importance of the hedgehog signaling pathway in development of head and neck squamous cell carcinoma (HNSCC)., Methods: The molecular profiles of the key regulatory genes of the pathway were analysed in the adjacent normal epithelium and tumor samples. The findings were validated in HNSCC cell line., Results: In the bioinformatical analysis, severe reduction in the expression of HHIP was evident in the datasets. The protein and mRNA expression studies in our sample pool revealed interplay of various isoforms of PTCH1 gene (PTCH1-1 and 1B) together with high/medium expression of GLI, SHH, SMO and HHIP in the basal/parabasal layers of the normal epithelium. As the disease progressed, severe downregulation of HHIP coupled with upregulation of GLI1 and differential expression pattern of various PTCH1 gene isoform was evident. Promoter methylation analysis of PTCH1 gene revealed the involvement of more than one promoter of PTCH1 in regulating the expression of different isoform of this gene during tumorigenesis. Treating the FaDu cell line with the demethylating agent 5-aza-2'-deoxycytidine reversed the methylation effects of HHIP and PTCH1 and de-activated the pathway. Also, reduced expression of HHIP-AS1 was observed in our sample pool suggesting multiple ways of regulation of the HHIP gene. Lastly, the patients with under expression of HHIP, HHIP-AS1, high expression of GLI1 showed worse five-year over-all survival trend., Conclusion: Dynamic promoter switching of PTCH1 and frequent inactivation of HHIP are the key regulatory events of hedgehog pathway activation in HNSCC., (Copyright © 2022 Elsevier GmbH. All rights reserved.)