P16 promotes the growth and mobility potential of breast cancer both in vitro and in vivo: the key role of the activation of IL-6/JAK2/STAT3 signaling.

P16 is the product of cyclin-dependent kinase 2 (CDKN2A) gene and plays multi-pronged roles in the cancer progression. Breast cancer (BC) is the most commonly diagnosed cancer type among females. In the current study, the potential function of P16 in the growth and metastasis of BC was investigated. Firstly, the expression statuses of P16 in different cancer types were investigated using Oncomine database and validated with corresponding cancer cell lines. Afterwards, the expression of P16 was knocked down in BC cell line BT-549 and the effect on the cell proliferation, sensitivity to paclitaxel (TAX), apoptosis, migration, and invasion abilities was assessed using CCK-8, Edu, flow cytometry, scratch, and transwell assays, respectively. The influence of P16 inhibition and P16 overexpression on the activity of IL-6/JAK/STAT3 signaling was explored. Additionally, the effect of P16 inhibition on the tumor growth was verified with a BC xenograft mice model. The abnormal expression of P16 was detected in BC cell line BT-549 as well as colorectal cancer and osteosarcoma cell lines. The inhibition of P16 suppressed the cell proliferation, invasion, and migration abilities while induced the apoptosis and sensitivity to TAX in BT-549 cells. At molecular level, P16 knockdown inhibited the expression of IL6ST and Survivin, and the phosphorylation of JAK2 and STAT3. However, the induced expression of P16 in P16-knockdown BT-549 cells restored the activity of IL-6/JAK2/STAT3 pathway. The results of in vitro assays were confirmed with BC xenograft models: the inhibition of P16 decreased the tumor growth rate. Findings outlined in the current study demonstrated that the inhibition of P16 decreased the growth and metastasis potential of BC cells by inhibiting IL-6/JAK2/STAT3 signaling.