MM-129 Counteracts 5-Fluorouracil-Induced Cellular Senescence in Colon Cancer via SIRT1/STAT3 Signaling Pathway

Cellular senescence plays a critical role in tumorigenesis and is recognized as a hallmark of colorectal cancer (CRC). Emerging evidence suggests that 5-fluorouracil (5-FU)-induced senescence may contribute to chemoresistance and tumor recurrence. Here, we investigated the effect of 5-FU on colon cancer cell senescence and whether MM-129 (pyrazolo[4,3-e]tetrazolo[4,5-b][1,2,4]triazine sulfonamide) can antagonize this activity. Senescence was identified by the expression of senescence-associated β-galactosidase (SA-β-gal) and cyclin-dependent kinase inhibitor 1A (p21) using qPCR, microscopy, flow cytometry, and immunohistochemistry. We also measured interleukin 6 (IL-6) and tumor necrosis factor (TNF-α) as key SASP cytokines, along with E-cadherin (CDH1), a marker of epithelial integrity. The SIRT1/STAT3 pathway was evaluated to elucidate the mechanism of MM-129's action. MM-129 counteracted 5-FU-induced senescence in colon cancer models, reducing p21 levels in zebrafish xenografts and the number of SA-β-gal-positive cells in vitro and in tumor tissues from DLD-1 and HT-29 mouse xenografts. MM-129 also inhibited senescence-associated responses by suppressing SASP cytokines (IL-6, TNF-α) and restoring E-cadherin (CDH1), and it modulated the SIRT1/STAT3 axis, which may underlie the observed senotherapeutic effects. In conclusion, MM-129 represents a novel senotherapeutic candidate. By modulating the SIRT1/STAT3 axis, it may suppress the SASP and weaken pro-survival signaling, thereby facilitating selective clearance of senescent cells. Integrating senotherapeutics with conventional cancer therapies may enhance efficacy and open new avenues for translational research.