YAP activation is an early event and a potential therapeutic target in liver cancer development

Background and Aims: Although the growth suppressor Hippo pathway has been implicated in hepatocellular carcinoma (HCC) pathogenesis, it is unknown at which stage of hepatocarcinogenesis its dysregulation occurs. We investigated in early rat and human preneoplastic lesions whether overexpression of the transcriptional co-activator Yes-associated protein (YAP) is an early event. Methods: The experimental model used is the Resistant-Hepatocyte (R-H) rat model. Gene expression was determined by qRT-PCR or immunohistochemistry. Forward genetic experiments were performed in human HCC cells and in murine oval cells. Results All foci of preneoplastic hepatocytes generated in rats 4 weeks after diethylnitrosamine (DENA) treatment, displayed YAP accumulation. This was associated with down-regulation of the β-TRCP ligase, known to mediate YAP degradation, and of microRNA-375, targeting YAP. YAP accumulation was paralleled by up-regulation of its target genes. Increased YAP expression was also observed in early dysplastic nodules and adenomas in humans. Animal treatment with verteporfin (VP), which disrupts the formation of the YAP–TEAD complex, significantly reduced preneoplastic foci and oval cell proliferation. In vitro experiments confirmed that VP-mediated YAP inhibition impaired cell growth in HCC and oval cells; notably, oval cell transduction with wild type or active YAP conferred tumorigenic properties in vitro and in vivo. Conclusions: These results suggest that i) YAP overexpression is an early event in rat and human liver tumorigenesis; ii) it is critical for the clonal expansion of carcinogen-initiated hepatocytes and oval cells, and, iii) VP-induced disruption of YAP-TEAD interaction may provide an important approach for the treatment of YAP-overexpressing cancers

FOLFIRI and Cetuximab Every Second Week for First-Line Treatment of KRAS Wild-Type Metastatic Colorectal Cancer According to Phosphatase and Tensin Homolog Expression : a Phase II Study

BACKGROUND: Retrospective studies have suggested that phosphatase and tensin homolog (PTEN) expression might predict the efficacy of cetuximab in patients with KRAS wild-type metastatic colorectal cancer (mCRC). The present study was designed to prospectively evaluate the efficacy of first-line irinotecan, fluorouracil, and folinate (FOLFIRI) plus cetuximab every second week according to PTEN expression. PATIENTS AND METHODS: Originally, patients with KRAS wild-type mCRC were randomly assigned to receive either FOLFIRI or cetuximab plus FOLFIRI (FOLFIRI-C). After a protocol amendment, the FOLFIRI arm was discontinued, and additional patients received FOLFIRI-C. Cox proportional hazard models were used to investigate the effect of PTEN and MET expression and BRAF and phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit \u3b1 mutations on progression-free survival (PFS) and overall survival (OS). RESULTS: A total of 35 and 54 patients received FOLFIRI and FOLFIRI-C, respectively. For the patients assigned to FOLFIRI and FOLFIRI-C, the median OS was 17.7 and 23.3 months and the median PFS was 8.2 and 6.6 months, respectively. For patients receiving FOLFIRI-C, the loss of PTEN expression did not affect PFS or OS. Significant interactions for PFS were detected between the MET expression levels (P = .047) and BRAF mutation (P = .018) and treatment. On univariate analysis, BRAF mutation was significantly associated with shorter OS for patients receiving either FOLFIRI-C (P = .016) or FOLFIRI (P = .035). Multivariate analysis confirmed the independent prognostic value of BRAF mutation on OS and that of MET expression levels on PFS (P = .025) and OS (P = .028) but only in the patients receiving FOLFIRI alone. Adverse events with FOLFIRI-C were consistent with those expected from FOLFIRI plus weekly cetuximab. CONCLUSION: Although prospective analysis of PTEN did not allow a validation of the prognostic value of this biomarker, an every second week cetuximab schedule, in addition to first-line FOLFIRI, was effective and well tolerated. The possible predictive value of MET expression levels warrants additional investigation