ASAP2 interrupts c-MET-CIN85 interaction to sustain HGF/c-MET-induced malignant potentials in hepatocellular carcinoma.

BACKGROUND: Sustained activation of hepatocyte growth factor (HGF)/c-MET signaling is a major driver of hepatocellular carcinoma (HCC) progression, but underlying mechanism is unclear. ArfGAP With SH3 Domain, Ankyrin Repeat And PH Domain 2 (ASAP2) can reportedly activate GTPases and promote receptor tyrosine kinase signaling. However, the exact role of ASAP2 in HCC, especially for c-MET activation, also remains elusive. METHODS: ASAP2 expression levels in HCC tissues and cells were quantified using qRT-PCR, western blot (WB) analysis, and immunohistochemistry staining. Cell counting kit-8 (CCK-8) and colony formation assays were performed to evaluate cell proliferation rates. Flow cytometry assays were conducted to assess apoptosis rates. Wound healing and Transwell assays were performed to determine cell migration and invasion capacities. Epithelial-mesenchymal transition (EMT)-related marker expression levels were also examined. Subcutaneous implantation and tail vein injection models were applied for in vivo growth and metastasis evaluations, respectively. Bioinformatics analyses of The Cancer Genome Atlas and STRING datasets were performed to explore ASAP2 downstream signaling. Co-immunoprecipitation and Cycloheximide chasing experiments were performed to assess protein-protein interactions and protein half-life, respectively. RESULTS: ASAP2 had higher expression levels in HCC tissues than in normal liver, and also predicted poor prognosis. Knocking down ASAP2 significantly impaired cell proliferation, migration, and invasion capacities, but promoted apoptosis in HCC cells in vitro. However, overexpression of ASAP2 achieved the opposite effects. In vivo experiments confirmed that ASAP2 could promote HCC cell growth and facilitate lung metastasis. Interestingly, ASAP2 was essential for triggering EMT. Gene Set Enrichment Analysis demonstrated that c-MET signaling was greatly enriched in ASAP2-high HCC cases. Additionally, c-MET signaling activity was significantly decreased following ASAP knockdown, evidenced by reduced c-MET, p-AKT, and p-ERK1/2 protein levels. Importantly, ASAP2 knockdown effectively attenuated HGF/c-MET signaling-induced malignant phenotypes. c-MET and ASAP2 expression levels were positively correlated in our cohort. Mechanistically, ASAP2 can directly bind to CIN85, thereby disrupting its interaction with c-MET, and can thus antagonize CIN85-induced c-MET internalization and lysosome-mediated degradation. Notably, knocking down CIN85 can rescue the observed inhibitory effects caused by ASAP2 knockdown. CONCLUSIONS: This study highlights the importance of ASAP2 in sustaining c-MET signaling, which can facilitate HCC progression.

Identification of a novel Calpain-2-SRC feed-back loop as necessity for ß-Catenin accumulation and signaling activation in hepatocellular carcinoma.

Rapid progression is the major cause of the poor prognosis of hepatocellular carcinoma (HCC); however, the underlying mechanism remained unclear. Here, we found Calpain-2 (CAPN2), a well-established protease that accelerates tumor progression in several malignancies, is overexpressed in HCC and acts as an independent predictor for poor outcomes. Furthermore, CAPN2 promoted the proliferation and invasion of HCC, and showed a positive correlation with the levels of invasion-related markers. Mechanistically, a novel CAPN2-SRC positive regulatory loop was identified upstream of ß-catenin to prevent its ubiquitination and degradation, and subsequently promoted HCC progression: CAPN2 could proteolyze PTP1B to form a truncation of approximately 42 kDa with increased phosphatase activity, resulting in reduced SRC Y530 phosphorylation and increased SRC kinase activity; meanwhile, CAPN2 itself was a bone fide substrate of SRC that was primarily phosphorylated at Y625 by SRC and exhibited increased proteolysis activity upon phosphorylation. Interestingly, the CAPN2-SRC loop could not only restrain most of cytoplasmic ß-catenin degradation by inhibiting GSK3ß pathway, but also prevented TRIM33-induced nuclear ß-catenin degradation even in ß-catenin-mutant cells. Present study identified a CAPN2-SRC positive loop responsible for intracellular ß-catenin accumulation and signaling activation, and targeting CAPN2 protease activity might be a promising approach for preventing HCC progression.

Serum STIP1, a Novel Indicator for Microvascular Invasion, Predicts Outcomes and Treatment Response in Hepatocellular Carcinoma.

Background: Previous studies reported that stress-induced phosphoprotein 1 (STIP1) can be secreted by hepatocellular carcinoma (HCC) cells and is increased in the serum of HCC patients. However, the therapy-monitoring and prognostic value of serum STIP1 in HCC remains unclear. Here, we aimed to systemically explore the prognostic significance of serum STIP1 in HCC. Methods: A total of 340 HCC patients were recruited to this study; 161 underwent curative resection and 179 underwent transcatheter arterial chemoembolization (TACE). Serum STIP1 was detected by enzyme-linked immunosorbent assay (ELISA). Optimal cutoff values for serum STIP1 in resection and TACE groups were determined by receiver operating characteristic (ROC) analysis. Prognostic value was assessed by Kaplan-Meier, log-rank, and Cox regression analyses. Predictive values of STIP1 for objective response (OR) to TACE and MVI were evaluated by ROC curves and logistic regression. Results: Serum STIP1 was significantly increased in HCC patients when compared with chronic hepatitis B patients or health donors (both P < 0.05). Optimal cutoff values for STIP1 in resection and TACE groups were 83.43 and 112.06 ng/ml, respectively. High pretreatment STIP1 was identified as an independent prognosticator. Dynamic changes in high STIP1 status were significantly associated with long-term prognosis, regardless of treatment approaches. Moreover, post-TACE STIP1 was identified as an independent predictor for OR, with a higher area under ROC curve (AUC-ROC) than other clinicopathological features. Specifically, pretreatment STIP1 was significantly increased in patients with microvascular invasion (MVI), and was confirmed as a novel, powerful predictor for MVI. Conclusions: Serum STIP1 is a promising biomarker for outcome evaluation, therapeutic response assessment, and MVI prediction in HCC. Integration serum STIP1 detection into HCC management might facilitate early clinical decision making to improve the prognosis of HCC.

CD73 sustained cancer-stem-cell traits by promoting SOX9 expression and stability in hepatocellular carcinoma.

BACKGROUND: Aberrant AKT activation contributes to cancer stem cell (CSC) traits in hepatocellular carcinoma (HCC). We previously reported that CD73 activated AKT signaling via the Rap1/P110ß cascade. Here, we further explored the roles of CD73 in regulating CSC characteristics of HCC. METHODS: CD73 expression modulations were conducted by lentiviral transfections. CD73+ fractions were purified by magnetic-based sorting, and fluorescent-activated cell sorting was used to assess differentiation potentials. A sphere-forming assay was performed to evaluate CSC traits in vitro, subcutaneous NOD/SCID mice models were generated to assess in vivo CSC features, and colony formation assays assessed drug resistance capacities. Stemness-associated gene expression was also determined, and underlying mechanisms were investigated by evaluating immunoprecipitation and ubiquitylation. RESULTS: We found CD73 expression was positively associated with sphere-forming capacity and elevated in HCC spheroids. CD73 knockdown hindered sphere formation, Lenvatinib resistance, and stemness-associated gene expression, while CD73 overexpression achieved the opposite effects. Moreover, CD73 knockdown significantly inhibited the in vivo tumor propagation capacity. Notably, we found that CD73+ cells exhibited substantially stronger CSC traits than their CD73- counterparts. Mechanistically, CD73 exerted its pro-stemness activity through dual AKT-dependent mechanisms: activating SOX9 transcription via c-Myc, and preventing SOX9 degradation by inhibiting glycogen synthase kinase 3ß. Clinically, the combined analysis of CD73 and SOX9 achieved a more accurate prediction of prognosis. CONCLUSIONS: Collectively, CD73 plays a critical role in sustaining CSCs traits by upregulating SOX9 expression and enhancing its protein stability. Targeting CD73 might be a promising strategy to eradicate CSCs and reverse Lenvatinib resistance in HCC.

Downregulation of XBP1 decreases serous ovarian cancer cell viability and enhances sensitivity to oxidative stress by increasing intracellular ROS levels.

Interaction between endoplasmic reticulum (ER) stress and oxidative stress contributes to the occurrence and development of various types of cancer. The X-box-binding protein 1 (XBP1), which is an important transcription factor in ER stress-related pathways, has also been reported to serve a protective role against oxidative stress. However, the role of XBP1 in serous ovarian cancer (SOC) remains elusive. The aim of the present study was to explore the biological function of XBP1 in SOC cells under normal or oxidative stress conditions. The expression of XBP1 was downregulated in the SOC cell lines A2780 and HO8910 by lentivirus-mediated short hairpin RNA (shRNA). Cell proliferative ability was evaluated by cell colony formation and viability assays. The sensitivity of ovarian cancer cells to oxidative stress was evaluated using cell survival rate and apoptotic rate, determined by the Cell Counting Kit-8 assay and flow cytometry, respectively. Reactive oxygen species (ROS) levels were measured by flow cytometry and cell immunofluorescence using a dichlorodihydrofluorescein diacetate probe. The mRNA and protein expression levels were detected by fluorescence quantitative polymerase chain reaction and western blot analysis, respectively. The results demonstrated that XBP1 was overexpressed in SOC compared with normal ovarian epithelial cells, and that downregulation of XBP1 significantly reduced cell proliferative ability. In addition, the downregulation of XBP1 significantly enhanced the sensitivity of SOC cells to H2O2 by increasing the intracellular ROS levels. The phosphorylation level of the mitogen-activated protein kinase (MAPK) p38 decreased in the cells of the XBP1-knockdown group. These results indicated that XBP1 may serve a protective role against oxidative stress in SOC cells, and the underlying molecular mechanism may be associated with the downregulation of phosphorylated p38. Therefore, targeting XBP1 may act synergistically with ROS inducers in the treatment of SOC.

Molecular profiling of mucinous epithelial ovarian cancer by weighted gene co-expression network analysis.

PURPOSE: In order to identify the molecular characteristics and improve the efficacy of early diagnosis of mucinous epithelial ovarian cancer (mEOC), here, the transcriptome profiling by weighted gene co-expression network analysis (WGCNA) has been proposed as an effective method. METHODS: The gene expression dataset GSE26193 was reanalyzed with a systematical approach, WGCNA. mEOC-related gene co-expression modules were detected and the functional enrichments of these modules were performed at GO and KEGG terms. Ten hub genes in the mEOC-related modules were validated using two independent datasets GSE44104 and GSE30274. RESULTS: 11 co-expressed gene modules were identified by WGCNA based on 4917 genes and 99 epithelial ovarian cancer samples. The turquoise module was found to be significantly associated with the subtype of mEOC. KEGG pathway enrichment analysis showed genes in the turquoise module significantly enriched in metabolism of xenobiotics by cytochrome P450 and steroid hormone biosynthesis. Ten hub genes (LIPH, BCAS1, FUT3, ZG16B, PTPRH, SLC4A4, MUC13, TFF1, HNF4G and TFF2) in the turquoise module were validated to be highly expressed in mEOC using two independent gene expression datasets GSE44104 and GSE30274. CONCLUSION: Our work proposed an applicable framework of molecular characteristics for patients with mEOC, which may help us to obtain a precise and comprehensive understanding on the molecular complexities of mEOC. The hub genes identified in our study, as potential specific biomarkers of mEOC, may be applied in the early diagnosis of mEOC in the future.

SIRT7 Exhibits Oncogenic Potential in Human Ovarian Cancer Cells.

BACKGROUND: Sirtuin7 (SIRT7) is a type of nicotinamide adenine dinucleotide oxidized form (NAD+)-dependent deacetylase and the least understood member of the sirtuins family; it is implicated in various processes, such as aging, DNA damage repair and cell signaling transduction. There is some evidence that SIRT7 may function as a tumor trigger for human malignancy. Here, we aimed to explore the biological function of SIRT7 in ovarian carcinoma cells and its potential mechanism. MATERIALS AND METHODS: Expression of SIRT7 in ovarian cancer cell lines was detected by western blotting. Transduced cell lines with SIRT7 knockdown or overexpression were constructed. Cell viability, cologenic, apoptosis-associated and motility assays were performed to elucidate the biological function of SIRT7 in ovarian cancer cells. RESULTS: SIRT7 demonstrated a higher level in ovarian cancer cell lines compared with normal cells. On the one hand, down-regulation of SIRT7 significantly reduced ovarian cancer cell growth, repressed colony formation and increased cancer cell apoptosis; on the other hand, up-regulation promoted the migration of cancer cells. Additionally, repression of SIRT7 also induced change in apoptosis-related molecules and subunits of the NF-κB family. CONCLUSIONS: In the present study, our data indicated that SIRT7 might play a role of oncogene in ovarian malignancy and be a potential therapeutic target.