SORBS1 Knockdown Resists S/G2 Arrest and Apoptosis Caused by Polyphyllin H-Induced DNA Damage in Pancreatic Cancer.

Objectives: The Sorbin and SH3 domain containing 1 (SORBS1), a protein linked to insulin signaling CBL interaction, was investigated for its role in pancreatic cancer apoptosis. This study explored polyphyllin H (PPH)'s ability to restore SORBS1-knockdown-mediated repair functions.

Methods: PANC-1 cells were divided into Blank, overexpression (OE), and knockdown groups. CCK-8 assays assessed proliferation and drug toxicity. Western blot and flow cytometry analyzed SORBS1 levels and PPH effects. Comet assays quantified DNA damage. Subcutaneous xenograft tumors in nude mice (Blank vs. knockdown) were treated with PPH to evaluate in vivo efficacy. SORBS1-H2AX gene correlation was analyzed Spearman rank clustering (p < 0.05).

Results: PPH suppressed pancreatic cancer growth in vitro/vivo, but its efficacy was attenuated by SORBS1 downregulation. Clinically, low SORBS1 correlated with poor prognosis. SORBS1 knockdown promoted tumor proliferation and reduced PPH-induced apoptosis. While PPH decreased tumor volume in both Blank and knockdown groups compared to controls, SORBS1 knockdown diminished PPH's inhibitory effects. Mechanistically, SORBS1 depletion mitigated PPH-triggered DNA damage, circumventing G2/M arrest by modulating WEE1, Cyclin A2, CDK1, and Cyclin B1, thereby impairing apoptosis.

Conclusion: SORBS1 knockdown counteracts PPH-mediated S/G2 arrest and apoptosis by alleviating DNA damage in pancreatic cancer. These findings highlight SORBS1 as a critical modulator of PPH's therapeutic potential, linking its expression to chemoresistance mechanisms.