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.

Pulmonary lymphoepithelioma-like carcinoma (LELC) is a subtype of non-small cell lung cancer (NSCLC) characterized by marked lymphocytic infiltration and association with Epstein–Barr virus (EBV). The molecular basis underlying the disease remains unclear. We sought to study the molecular landscape by multiple approaches including whole genomic sequencing, capture-based targeted sequencing, fluorescent in situ hybridization and immunohistochemistry. Tumor cells from 57 EBV-positive pulmonary LELCs were isolated by careful microdissection prior to genomic sequencing. Integrated analysis revealed a distinct genomic landscape of low TP53 mutation rate (11%), low incidence of known drivers in the RTK/RAS/RAF (11%) and PI3K/AKT/mTOR pathways (7%), but enriched for loss-of-function mutations in multiple negative regulators of the NF-κB pathway. High level programmed cell death ligand-1 (PD-L1) expression was shown with 47% and 79% of the cases showing positive PD-L1 immunoreactivity at ≥50% and ≥1% tumor proportion score, respectively. Subsets of the patients with actionable fibroblast growth factor receptor 3 (FGFR3) aberrations (4%) and mismatch repair deficiency (4%) were potentially eligible for precision medicine. Pulmonary LELC showed a distinct genomic landscape, different from major NSCLC subtypes but resembled that of EBV-associated nasopharyngeal carcinoma. Our work facilitated the understanding of molecular basis underlying pulmonary LELC to explore potential therapeutic options.

To investigate the role of DNA mismatch repair status (MMR) in survival of endometrioid endometrial cancer in Hong Kong Chinese women and its correlation to clinical prognostic factors, 238 patients with endometrioid endometrial cancer were included. Tumor MMR status was evaluated by immunohistochemistry. Clinical characteristics and survival were determined. Association of MMR with survival and clinicopathological parameters were assessed. MMR deficiency (dMMR) was found in 43 cases (16.5%). dMMR was associated with poor prognostic factors including older age, higher stage, higher grade, larger tumor size and more radiotherapy usage. Long-term survival was worse in dMMR compared to the MMR proficient group. The dMMR group had more deaths, shorter disease-specific survival (DSS), shorter disease-free survival (DFS), less 10-year DSS, less 10-year DFS, and more recurrence. The 5-year DSS and 5-year DFS in the dMMR group only showed a trend of worse survival but did not reach statistical significance. In conclusion, dMMR is present in a significant number of endometrioid endometrial cancers patients and is associated with poorer clinicopathological factors and survival parameters in the long run. dMMR should be considered in the risk stratification of endometrial cancer to guide adjuvant therapy and individualisation for longer follow up plan.