MicroRNAs (miRNAs) have been reported to play an important role in tumorigenesis. In this study, the role of miR-15a and miR-16-1 in gastric adenocarcinoma (GAC) was investigated. The expression of miR-15a and miR-16-1 in cell lines and primary tumors was examined by miRNA qRT-PCR. Proliferative assays, colony formation, cell invasion and migration, flow cytometry analysis and in vivo study were performed by ectopic expression of miR-15a and miR-16-1. The putative target genes of miR-15a and miR-16-1 were explored by TargetScan and further validated. We found that miR-15a and miR-16-1 were down-regulated in GAC cell lines and primary tumor samples compared with normal gastric epithelium. Functional study demonstrated that ectopic expression of miR-15a and miR-16-1 suppressed cell proliferation, monolayer colony formation, invasion and migration, and xenograft formation in vivo. In addition, miR-15a and miR-16-1 induced G0/G1 cell cycle arrest which was further confirmed by Western blot and qRT-PCR of related cell cycle regulators. YAP1 was confirmed to be a functional target of miR-15a and miR-16-1 in GAC. YAP1 re-expression partly abrogated the inhibitory effect of miR-15a and miR-16-1 in GAC cells. In clinical samples, YAP1 protein expression shows negative correlation with miR-15a and miR-16-1 expression. In conclusion, targeting YAP1 by tumor suppressor miRNA miR-15a and miR-16-1 plays inhibitory effect and this might have a therapeutic potential in GAC.

The oncogenic PI3K/Akt/mTOR pathway is frequently activated in HCC. Data on the mTOR inhibitor, temsirolimus, is limited in HCC patients with concomitant chronic liver disease. The objectives of this study were: (1) In phase I, to determine DLTs and MTD of temsirolimus in HCC patients with chronic liver disease; (2) In phase II, to assess activity of temsirolimus in HCC, and (3) to explore potential biomarkers for response. Major eligibility criteria included histologically confirmed advanced HCC and adequate organ function. In Phase I part of the study, temsirolimus was given weekly in 3-weekly cycle; dose levels were 20 mg (level 1), 25 mg (level 2) and 30 mg (level 3). The MTD was used in the subsequent phase II part; the primary endpoint was PFS and secondary endpoints were response and OS. In addition, exploratory analysis was conducted on pre-treatment tumour tissues to determine stathmin, pS6, pMTOR or p-AKT expressions as potential biomarkers for response. Overall survival and PFS were calculated using the Kaplan-Meier method. Reassessment CT scans were done every 6 weeks. All adverse events were reported using CTCAE v3. The Phase I part consisted of 19 patients, 2 of 6 patients at level 3 experienced DLT; dose level 2 was determined to be the MTD. The phase II part consisted of 36 patients. Amongst 35 assessable patients, there were 1 PR, 20 SD and 14 PD. Overall, the median PFS was 2.83 months (95% C.I. 1.63-5.24). The median OS was 8.89 months (95% C.I. 5.89-13.30). Grade ≥ 3 that occurred in > 10% of patients included thrombocytopenia (4) and hyponatraemia (4). Exploratory analysis revealed that disease stabilization (defined as CR + PR + SD > 12 weeks) in tumours having high and low pMTOR H-scores to be 70% and 29% respectively (OR 5.667, 95% CI 1.129-28.454, p = 0.035). In HCC patients with chronic liver disease, the MTD of temsirolimus was 25 mg weekly in a 3-week cycle. The targeted PFS endpoint was not reached. However, further studies to identify appropriate patient subgroup are warranted. This study has been registered in ClinicalTrials.gov (Id: NCT00321594 ) on 1 December 2010.

Colorectal cancer (CRC) is a kind of solid tumor and the third most common cancer type in the world. It is a heterogeneous disease characterized by genetic and epigenetic aberrations. The TP53 mutation is the key step driving the transition from adenoma to adenocarcinoma. The functional roles of TP53 mutation in tumor development have been comprehensively investigated. In CRC, TP53 mutation was associated with poor prognosis and chemoresistance. A gain of function (GOF) of p53 mutants promotes cell proliferation, migration and invasion through multiple mechanisms. Restoring wild type p53 function, depleting p53 mutants, or intervention by targeting the oncogenic downstreams provides potential therapeutic strategies. In this review, we comprehensively summarize the GOF of p53 mutants in CRC progression as well as in some other solid tumors, and discuss the current strategies targeting p53 mutants in malignancies.

NF-κB signaling pathway plays an important role in gastric carcinogenesis. The basic expression and functional role of NFKB1 and RELA (components of canonical NF-κB pathway) in gastric cancer (GC) have not been well elucidated. In this study, the role of NFKB1 and RELA in gastric tumorigenesis will be investigated and their regulation by microRNAs (miRNAs) will be deeply explored. The mRNA and protein expression of NFKB1 and RELA were investigated by qRT-PCR and Western blot in GC cell lines and primary tumors. The functional roles of NFKB1 and RELA in GC were demonstrated by MTT proliferation assay, monolayer colony formation, cell invasion and migration, cell cycle analysis and in vivo study through siRNA mediated knockdown. Identification of NFKB1 as a direct target of tumor suppressor miRNA miR-508-3p was achieved by expression regulation assays together with dual luciferase activity experiments. NFKB1 and RELA were up-regulated in GC cell lines and primary tumors compared with normal gastric epithelium cells and their upregulation correlation with poor survival in GC. siRNA mediated knockdown of NFKB1 or RELA exhibited anti-oncogenic effect both in vitro and in vivo. NFKB1 was further revealed to be a direct target of miR-508-3p in gastric tumorigenesis and their expression showed negative correlation in primary GC samples. miR-508-3p was down-regulated in GC cells compared with normal gastric epithelium samples and its ectopic expression in GC cell lines also exerts tumor suppressor function. NFKB1 re-expression was found to partly abolish the tumor-suppressive effect of miR-508-3p in GC. All these findings supports that canonical NF-κB signaling pathway is activated in GC at least by the inactivation of miR-508-3p and this might have therapeutic potential in GC treatment.

Patients with colorectal cancer (CRC) have a high incidence of regional and distant metastases. Although metastasis is the main cause of CRC-related death, its molecular mechanisms remain largely unknown. Using array-CGH and expression microarray analyses, changes in DNA copy number and mRNA expression levels were investigated in human CRC samples. The mRNA expression level of RASAL2 was validated by qRT-PCR, and the protein expression was evaluated by western blot as well as immunohistochemistry in CRC cell lines and primary tumors. The functional role of RASAL2 in CRC was determined by MTT proliferation assay, monolayer and soft agar colony formation assays, cell cycle analysis, cell invasion and migration and in vivo study through siRNA/shRNA mediated knockdown and overexpression assays. Identification of RASAL2 involved in hippo pathway was achieved by expression microarray screening, double immunofluorescence staining and co-immunoprecipitation assays. Integrated genomic analysis identified copy number gains and upregulation of RASAL2 in metastatic CRC. RASAL2 encodes a RAS-GTPase-activating protein (RAS-GAP) and showed increased expression in CRC cell lines and clinical specimens. Higher RASAL2 expression was significantly correlated with lymph node involvement and distant metastasis in CRC patients. Moreover, we found that RASAL2 serves as an independent prognostic marker of overall survival in CRC patients. In vitro and in vivo functional studies revealed that RASAL2 promoted tumor progression in both KRAS/NRAS mutant and wild-type CRC cells. Knockdown of RASAL2 promoted YAP1 phosphorylation, cytoplasm retention and ubiquitination, therefore activating the hippo pathway through the LATS2/YAP1 axis. Our findings demonstrated the roles of RASAL2 in CRC tumorigenesis as well as metastasis, and RASAL2 exerts its oncogenic property through LATS2/YAP1 axis of hippo signaling pathway in CRC.

Yin Yang 1 (YY1) is a transcription factor that regulates diverse biological processes and increasing recognized to have important roles in carcinogenesis. The function and clinical significance of YY1 in gastric adenocarcinoma (GAC) have not been elucidated.