Nrf2 is a key transcription factor for genes coding for antioxidants, detoxification enzymes, and multiple drug resistance and it also confers resistance to anticancer drugs. Here, we hypothesized that mutant p53 could upregulate Nrf2 expression at the transcriptional level, thereby conferring cisplatin resistance in non-small cell lung cancer (NSCLC). Luciferase reporter assays and real-time PCR analysis indicated that the Nrf2 promoter activity and its mRNA levels were markedly suppressed by wild-type p53, but not by mutant p53. Chromatin immunoprecipitation (ChIP) further confirmed that wild-type p53 binds at the p53 putative binding site to block Sp1 binding to the Nrf2 promoter and consequently to suppress the Nrf2 promoter activity. The MTT assay indicated that an increase in Nrf2 expression by mutant p53 is responsible for cisplatin resistance. Among the Nrf2 downstream genes, Bcl-2 and Bcl-xL contribute more strongly to Nrf2-mediated cisplatin resistance when compared with heme oxygenase 1 (HO-1). Cox regression analysis showed that patients with high-Nrf2, high-Bcl-2, high-Bcl-xL mRNA tumors were more commonly occurred unfavorable response to cisplatin-based chemotherapy than their counterparts. The prognostic significance of Nrf2 mRNA levels on OS and RFS was also observed in patients who have received cisplatin-based chemotherapy, particularly in p53-mutant patients. Collectively, mutant p53 may confer cisplatin resistance via upregulation of Nrf2 expression, and Nrf2 mRNA level may predict chemotherapeutic response and outcomes in NSCLC.

The dimeric interface of severe acute respiratory syndrome coronavirus main protease is a potential target for the anti-SARS drug development. We have generated C-terminal truncated mutants by serial truncations. The quaternary structure of the enzyme was analyzed using both sedimentation velocity and sedimentation equilibrium analytical ultracentrifugation. Global analysis of the combined results showed that truncation of C-terminus from 306 to 300 had no appreciable effect on the quaternary structure, and the enzyme remained catalytically active. However, further deletion of Gln-299 or Arg-298 drastically decreased the enzyme activity to 1-2% of wild type (WT), and the major form was a monomeric one. Detailed analysis of the point mutants of these two amino acid residues and their nearby hydrogen bond partner Ser-123 and Ser-139 revealed a strong correlation between the enzyme activity loss and dimer dissociation.

Purpose: Interleukin-10 (IL-10) determines virus persistent infection and promotes viral-associated tumor progression via tumor immune escape. However, the role of IL-10 in tumor progression and prognosis in lung adenocarcinoma remains controversial.Experimental Design: To investigate how IL-10 is regulated by HPV E6, IL-10 promoter was constructed to understand which transcriptional factor could be responsible for its transcription. To verify which molecule could be responsible for IL-10-mediated soft agar growth and invasion capability, PCR array and mechanistic strategies were conducted. IL-10 and CIP2A mRNA levels in lung tumors from patients with lung cancer were determined by real-time reverse transcription PCR. The prognostic value of both molecules on survival was estimated by Cox regression model.Results: Mechanistic studies showed that IL-10 protein and mRNA expression was decreased in E6 knockdown TL1 cells and increased in E6-overexpressing TL4 cells.

The mechanism underlying tumor aggressiveness and cetuximab (CTX) resistance in KRAS-wild-type (KRAS -WT) colorectal cancer remains obscure. We here provide evidence that DDX3 promoted soft agar growth and invasiveness of KRAS-WT cells, as already confirmed in KRAS-mutated cells. Mechanistically, increased KRAS expression induced ROS production, which elevated HIF-1α and YAP1 expression. Increased HIF-1α persistently promoted DDX3 expression via a KRAS/ROS/HIF-1α feedback loop. DDX3-mediated aggressiveness and CTX resistance were regulated by the YAP1/SIX2 axis in KRAS-WT cells and further confirmed in animal models. Kaplan-Meier and Cox regression analysis indicated that DDX3, KRAS, and YAP1 expression had prognostic value for OS and RFS in KRAS-WT and KRAS-mutated tumors, but SIX2 and YAP1/SIX2 were prognostic value only in KRAS-WT patients. The observation from patients seemed to support the mechanistic action of cell and animal models. We therefore suggest that combining YAP1 inhibitors with CTX may therefore suppress DDX3-mediated tumor aggressiveness and enhance CTX sensitivity in KRAS-WT colorectal cancer.

Programmed death ligand (PD-L1) expression was associated with tumor immune escape and subsequent poor prognosis in non-small cell lung cancer (NSCLC). This expression was higher in patients with EGFR-mutated NSCLC tumors than in those with EGFR-wild-type (WT) NSCLC tumors. We therefore hypothesized that poor prognosis mediated by higher PD-L1 may be partially through conferring resistance to tyrosine kinase inhibitor (TKI) in NSCLC regardless of EGFR mutation. The change in PD-L1 expression following gene manipulation corresponded with changes in expression of HIF-1α and YAP1. The expression of HIF-1α and YAP1 was concomitantly decreased by PD-L1 silencing or by ROS scavenger treatment (N-acetylcysteine, NAC); however, a ROS inducer treatment (pyocyanin) completely reversed the decreased expression of both genes in EGFR-mutated and -wild-type (WT) NSCLC cells. The MTT assay indicated that the inhibitory concentration of gefitinib yielding 50% cell viability (IC50) depended on PD-L1-mediated YAP1 expression. Mechanistic studies indicated that upregulation of YAP1 by PD-L1 might be responsible for EGFR mutation-independent TKI resistance via the ROS/HIF-1α axis. An unfavorable TKI response was more common in patient tumors with high PD-L1 or YAP1 mRNA expression than in patient tumors with low mRNA expression of these genes. In conclusion, PD-L1 might confer EGFR mutation-independent TKI resistance in NSCLC cells via upregulation of YAP1 expression.

DDX3, a subunit of CK1ε, phosphorylates Dvl2 to promote β-catenin activation. Overexpression of the Dvl2 protein results in potent activation of β-catenin/TCF signaling in colorectal cancer. Therefore, we hypothesized that DDX3 might promote tumor invasion via the CK1ε/Dvl2 axis due to β-catenin/TCF activation. Western blotting showed that β-catenin expression was decreased by DDX3 knockdown and increased by DDX3 overexpression in colorectal cancer cells. The TCF promoter activity and invasion capability were concomitantly increased and decreased by DDX3 manipulation in these cells. The invasion capability in colon cancer cells and xenograft lung tumor nodules induced by a DDX3-overexpressing T84 stable clone in tail-vein injection model were nearly suppressed by inhibitors of CK1ε (PF4800567) and β-catenin/TCF signaling (XAV939). Among colorectal cancer patients, DDX3 expression was positively correlated with the expression of pDvl2 and nuclear β-catenin in tumor tissues. The expression of pDvl2 occurred more frequently in high-nuclear than in low-nuclear β-catenin tumors. A prognostic significance of DDX3, pDvl2, and nuclear β-catenin on overall survival and relapse free survival was observed in this study population. We therefore suggest CK1ε or β-catenin/TCF signaling as potential targets for improving tumor regression and outcomes in colorectal cancer, particularly tumors with high-DDX3/high-nuclear β-catenin or high-DDX3/high-pDvl2/high-nuclear β-catenin expression.

MiR-184 as a tumor suppressor miR inhibits cell proliferation and invasion capability via targeting CDC25A and c-Myc. Low miR-184 level may predict worse prognosis in NSCLC patients.

No abstract