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BACKGROUND Our primary aim of the current study was to explore the correlation between plasma CRABP2 and migration, proliferation and invasion of non-small cell lung cancer (NSCLC) cells. METHODS Human lung cancer cell line A549 was used in the present study, which was cultured in 6-well plates (1 × 106 cells/well) and then transfected with pcDNA-CRABP2 and pcDNA, siRNA with the use of Lipofectamine 2000 based on the manufacturer's protocol. The expression of CRABP2 mRNA was detected through real-time PCR. Proliferation was further detected using MTT assays, and apoptosis was monitored and recorded with the application of flow cytometry. The expression of E-cadherin, MMP9, vimentin and related pathway proteins was detected by Western blotting assays. Transwell assays and cell scratch assays were utilized for the detection of migration and invasion ability of A549 cells. RESULTS RT-PCR results showed The CRABP2 mRNA transcript levels in the CRABP2 overexpression group were higher when comparing those of the empty vector group (P < 0.05). By MTT assays, CRABP2 overexpression promoted cellular proliferation, while CRABP2 downregulation inhibited cellular proliferation. CRABP2 overexpression inhibited cell apoptosis and promoted cellular proliferation. The number of TUNEL staining positive cells was the lowest in the CRABP2 overexpression group, and the siRNA transfection group had increased apoptosis. CRABP2 downregulation reduced EMT in cells and cell migration and invasion reflected from western blotting results and cell migration and invasion assay results, respectively. CONCLUSION Inhibition of plasma CRABP2 expression offers the potential in terms of reducing the expression of MAPKs and proteins in the NF-κB pathway and inhibiting the proliferation and migration of NSCLC cells, which is ideally suited for further treatment for NSCLC.

This article aims to explore the effects and possible mechanism of miR-543 on small-cell lung carcinoma (SCLC) cells. The respective levels of miR-543 in lung carcinoma tissues, para-cancerous tissues, human normal lung cells MRC-9, and SCLC cells were detected by RT-qPCR. The proliferation, apoptosis, and migration of SCLC cells were detected after the miR-543 level in SCLC cells was altered by miRNA mimics and inhibitors. The levels of apoptosis-related proteins and potential downstream targeted proteins of miR-543 were detected by western blots. The study revealed that KNTC1 was highly expressed in lung carcinoma tissues and SCLC cells (P < 0.01). It also showed that knockdown of miR-543 can inhibit the proliferation and migration of SCLC cells, induce apoptosis, and increase the level of apoptosis-related proteins. These changes were reversed by the addition of mimics that increased miR-543 levels. The level of miR-543 was positively correlated with the protein expression level of downstream MUC1, β-catenin, and CDC42 in SCLC cells, suggesting that miR-543 may play a role through them. Thus this study concludes that MiR-543 can affect the function of SCLC cells, which may play a crucial role in the presence and development of SCLC.

Tumor resistance is the main cause of treatment failure and is associated with many tumor factors. Jaridon 6, a new diterpene extracted from Rabdosia rubescens (Hemsl.) Hara, which has been previously extracted by our research team, has been tested having more obvious advantages in resistant tumor cells. However, its mechanism is unclear. In this study, we studied the effect and the specific mechanism of Jaridon 6 in resistant gastric cancer cells. Cytotoxicity test, colony test, western blotting, and nude test verified the anti-drug resistance ability of Jaridon 6 in the MGC803/PTX and MGC803/5-Fu cells. Jaridon 6 has shown obvious inhibitory effects in the sirtuin 1 (SIRT1) enzyme test. Transmission electron microscopy and immunofluorescence tests further proved the autophagic action of Jaridon 6. Jaridon 6 could inhibit the proliferation of the resistant gastric cancer cell in vivo and in vitro. Jaridon 6 inhibited SIRT1 enzyme and induced autophagy by inhibiting the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway. Thus, it may be considered for treating gastric cancer resistance by individual or combined administration, as an SIRT1 inhibitor and autophagy inducer.

Neurofibromatosis type 2 (NF2) is a genetic condition characterized by inactivation of the NF2 tumor suppressor gene and the development of schwannomas. The NF2 gene product, merlin, is activated (dephosphorylated) by contact inhibition and promotes growth suppression. We investigated the effect of curcumin (diferuloylmethane), a molecule with anti-inflammatory and antitumorigenic properties, on human schwannoma cell growth and the regulation of merlin by curcumin in both NF2 cells and neuroblastoma (non-NF2) cells. Curcumin inhibited the growth of HEI-193 schwannoma cells in vitro and downregulated the phosphorylation of Akt and extracellular signal–regulated kinase 1/2. Curcumin also activated MYPT1-pp1δ (a merlin phosphatase), which was associated with dephosphorylation of merlin on serine 518, an event that results in the folding of merlin to its active conformation. In addition, curcumin induced apoptosis and generated reactive oxygen species in HEI-193 cells. Consequently, hsp70 was upregulated at the mRNA and protein levels, possibly serving as a mechanism of escape from curcumin-induced apoptosis and growth inhibition. Endogenous merlin and hsp70 proteins interacted in HEI-193 schwannoma and SK-N-AS neuroblastoma cells. The combination of curcumin and an hsp inhibitor synergistically suppressed schwannoma cell growth. Our results provide a rationale for combining curcumin and KNK437 in the treatment of NF2. Mol Cancer Ther; 10(11); 2094–103. ©2011 AACR.

Background Imatinib is a tyrosine kinase inhibitor that is used to treat chronic myelogenous leukemia (CML). BCR-ABL mutations are associated with failure of imatinib treatment in many CML patients. LYN kinase regulates survival and responsiveness of CML cells to inhibition of BCR-ABL kinase, and differences in LYN regulation have been found between imatinib-sensitive and -resistant CML cell lines. Methods We evaluated cells from 12 imatinib-resistant CML patients with mutation-negative BCR-ABL and from six imatinib-sensitive patients who discontinued therapy because of imatinib intolerance. Phosphorylation of BCR-ABL and LYN was assessed in patient cells and cell lines by immunoblotting with activation state-specific antibodies, co-immunoprecipitation studies, and mass spectroscopy analysis of phosphopeptides. Cell viability, caspase activation, and apoptosis were also measured. Mutations were analyzed by sequencing. The effect of silencing LYN with short interfering RNAs (siRNAs) or reducing activation by treatment with tyrosine kinase inhibitors was evaluated in cell lines and patient cells. Results Imatinib treatment suppressed LYN phosphorylation in cells from imatinib-sensitive CML patients and imatinib-sensitive cell lines. Imatinib treatment blocked BCR-ABL signaling but did not suppress LYN phosphorylation in cells from imatinib-resistant patients, and persistent activation of LYN kinase was not associated with mutations in LYN kinase or its carboxyl-terminal regulatory domains. Unique LYN phosphorylation sites (tyrosine-193 and tyrosine-459) and associated proteins (c-Cbl and p80) were identified in cells from imatinib-resistant patients. Reducing LYN expression (siRNA) or activation (dasatinib) was associated with loss of cell survival and cytogenetic or complete hematologic responses in imatinib-resistant disease. Conclusions LYN activation was independent of BCR-ABL in cells from imatinib-resistant patients. Thus, LYN kinase may be involved in imatinib resistance in CML patients with mutation-negative BCR-ABL and its direct inhibition is consistent with clinical responses in these patients.

Norcantharidin (NCTD), the demethylated analog of the Chinese medicine cantharidin, exhibits anti-myeloma activity by inactivating nuclear factor-κB (NF-κB), which is implicated in multiple myeloma (MM) cell survival and resistance to bortezomib (BTZ). We investigated whether NCTD could potentiate the anti-tumor activity of BTZ in MM. NCTD inhibited the proliferation of MM cells and potentiated the anti-myeloma effects of BTZ by down-regulating IKKα and p-IκBα, which induced the accumulation of IκBα and inhibited the constitutive activation of NF-κB. This effect was correlated with the suppression of NF-κB-regulated gene products. Furthermore, a chemotherapy-potentiating effect of NCTD on BTZ was also observed in vivo. Our study demonstrated that NCTD and BTZ exhibit significant therapeutic effects on MM through the NF-κB signal pathway in vitro and in vivo. Future studies will investigate the combined effects of NCTD and BTZ in patients with MM.

Expression of the tumor suppressor gene TUSC2 is reduced or absent in most lung cancers and is associated with worse overall survival. In this study, we restored TUSC2 gene expression in several wild type EGFR non-small cell lung cancer (NSCLC) cell lines resistant to the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor erlotinib and analyzed their sensitivity to erlotinib in vitro and in vivo. A significant inhibition of cell growth and colony formation was observed with TUSC2 transient and stable expression. TUSC2-erlotinib cooperativity in vitro could be reproduced in vivo in subcutaneous tumor growth and lung metastasis formation lung cancer xenograft mouse models. Combination treatment with intravenous TUSC2 nanovesicles and erlotinib synergistically inhibited tumor growth and metastasis, and increased apoptotic activity. High-throughput qRT-PCR array analysis enabling multi-parallel expression profile analysis of eighty six receptor and non-receptor tyrosine kinase genes revealed a significant decrease of FGFR2 expression level, suggesting a potential role of FGFR2 in TUSC2-enhanced sensitivity to erlotinib. Western blots showed inhibition of FGFR2 by TUSC2 transient transfection, and marked increase of PARP, an apoptotic marker, cleavage level after TUSC2-erlotinb combined treatment. Suppression of FGFR2 by AZD4547 or gene knockdown enhanced sensitivity to erlotinib in some but not all tested cell lines. TUSC2 inhibits mTOR activation and the latter cell lines were responsive to the mTOR inhibitor rapamycin combined with erlotinib. These results suggest that TUSC2 restoration in wild type EGFR NSCLC may overcome erlotinib resistance, and identify FGFR2 and mTOR as critical regulators of this activity in varying cellular contexts. The therapeutic activity of TUSC2 could extend the use of erlotinib to lung cancer patients with wildtype EGFR.