ObjectiveTo investigate the impact of aberrant SKI expression and its mutations on the biological characteristics of cholangiocarcinoma cell lines QBC939 and RBE， and to explore the underlying molecular mechanisms. MethodsThe Gene Expression Profiling Interactive Analysis 2 （GEPIA2） database was utilized to analyze SKI expression and its clinical relevance in cholangiocarcinoma patients. Lentiviral transduction was employed to establish QBC939 and RBE cell lines with stable SKI overexpression， mutation， or knockdown. Cell proliferation was assessed using CCK-8， colony formation， and EdU assays. Apoptosis and cell cycle distribution were analyzed by flow cytometry. Cell migration was evaluated using Transwell and wound healing assays. The effect of SKI over-expression， mutation， or knockdown on key proteins （SMAD2， SMAD3， SMAD4） in the transforming growth factor-β （TGF-β）/Small mothers against decapentaplegic （SMAD） signaling pathway was examined by Western blot. ResultsCompared to SKI overexpression alone， the introduction of SKI mutations significantly promoted S-phase progression， enhanced proliferation and migration， and inhibited apoptosis. Mechanistically， SKI mutations suppressed the phosphorylation of SMAD2 and SMAD3 proteins， thereby inhibiting the transcriptional activity of the TGF-β signaling pathway. Conversely， SKI knockedown produced the opposite effects. ConclusionSKI gene mutation acts as a gain-of-function genetic alteration， exerting an oncogenic role in cholangiocarcinoma cells. The primary mechanism involves the inhibition of the TGF-β/SMAD signaling pathway， which in turn promotes proliferation and cell cycle progression， and suppresses apoptosis in QBC939 and RBE cells， ultimately driving tumor progression.

Objective : To investigate the effects of C-type lectin domain family 5，member A( CLEC5A) on the pro- liferation，apoptosis，and cell cycle of leukemia cell lines THP-1 and K562，and the underlying mechanism． Methods : The expression of CLEC5A in leukemia patients was investigated in the GEPIA database. Recombined plasmid containing CLEC5A was transfected into THP-1 and K562 cells for overexpression of CLEC5A．Small interfering RNA(siRNA) was used to knock down the endogenous CLEC5A in leukemia cells．CCK-8 and EdU assays were used to assess the leukemia cells proliferation．Flow cytometry was used to assess cell cycle．Flow cytometry was used to assess cell apoptosis under hydrogen peroxide( H2 O2 ) stress．The RNA sequencing( RNA-seq) and pathway enrichment analysis were used to analyze the signal pathways of significant enrichment of up-regulated or down-reg- ulated genes after knocking down CLEC5A gene．Protein expression levels of several members in AKT1 / mTOR and p53 signaling pathways were detected by Western blot assays. Results : CLEC5A was significantly up-regulated in bone marrow tissues of leukemia patients compared to the matched non-tumor tissues of healthy individuals．Knock- down of CLEC5A significantly reduced the proliferation(all P＜0. 01) and S phase progression(all P＜0. 05) ，and increased the apoptosis(all P＜0. 001) under H2 O2 stress，in THP-1 and K562 cells．Conversely，overexpression of CLEC5A significantly increased the proliferation(all P ＜0. 001) and S phase progression ( all P ＜0. 01) ，and re- duced the apoptosis(all P＜0. 01) under H2 O2 stress，in THP-1 and K562 cells．The uregulated genes were sig- nificantly enriched in AKT1-mTOR and other signal pathways after knocking down CLEC5A，while the down-regula- ted genes were significantly enriched in cell cycle signal pathways．CLEC5A in leukemia cells significantly reduced the genes expression levels of BAX and p53，and significantly induced the gene expression levels of BCL-2 and phosphorylation levels of AKT1 and mTOR proteins． Conclusion CLEC5A increases the cell cycle and proliferation and inhibits cells apoptosis in THP-1 and K562 cells，and the mechanism may be related to activating the AKT / mTOR and p53 signaling pathways.