SOCS3 overexpression enhances ADM resistance in bladder cancer T24 cells.

Objective: JAK-STAT3 signaling pathway widely participates in cell proliferation and apoptosis. Suppressor of cytokine signaling 3 (SOCS3) is a negative regulator of JAK-STAT3. SOCS3 downregulation is associated with drug resistance in breast cancer and leukemia. However, its role in bladder cancer drug resistance is still unclear. This study established ADM resistant bladder cancer cell model to investigate the role of SOCS3-JAK/STAT3 signaling pathway ADM resistance.
Materials and Methods: ADM drug resistant cell line T24/ADM was established. SOCS3, p-JAK2, p-JAK3, and Bcl-2 expressions in T24/ADM, T24, and HBEC cells were compared. Cell proliferation and apoptosis were evaluated by flow cytometry. T24/ADM cells were divided into five groups, including control, pSicoR-blank, pSicoR-SOCS3, FLLL32, and pSicoR-SOCS3 + FLLL32 groups. Cell proliferation was determined by EdU staining.
Results: SOCS3 was reduced, while p-JAK2, p-STAT3, and Bcl-2 expressions upregulated in T24 cells compared with HBEC cells. T24/ADM cells exhibited lower SOCS3, higher p-JAK2, p-STAT3, and Bcl-2 levels than T24 cells. Cell apoptosis was higher, whereas cell proliferation was weaker in T24 cells compared with T24/ADM cells. SOCS3 overexpression and/or FLLL32 treatment significantly downregulated p-JAK2, p-STAT3, and Bcl-2 expressions, attenuated cell proliferation, and elevated sensitivity to ADM induced cell apoptosis.
Conclusions: SOCS3 reduction was associated with bladder cancer sensitivity to ADM. SOCS3 overexpression decreased JAK-STAT3 signaling pathway activity, declined Bcl-2 expression, inhibited cell proliferation, elevated cell apoptosis, and enhanced ADM sensitivity in T24 cells.