Effect of SOCS1 silencing on proliferation and apoptosis of melanoma cells: An in vivo and in vitro study

Abstract

This study aimed to investigate the effect of SOCS1 silencing on the proliferation and apoptosis of melanoma cells by in vivo and in vitro studies. Immunohistochemical staining was used to detect SOCS1 expression in melanoma tissues and pigmented nevi. Quantitative real-time polymerase chain reaction and western blotting were applied to detect the messenger RNA and protein expressions of SOCS1 in primary human melanocytes and malignant melanoma cell lines (A375, SK-MEL-5, M14, and MV3). Melanoma cells were assigned into mock, negative small interfering RNA, and SOCS1-small interfering RNA groups. The proliferation, cell cycle and apoptosis, and messenger RNA expression of SOCS1 in MV3 and A375 cells were detected using MTT assay, flow cytometry, and quantitative real-time polymerase chain reaction, respectively. The expressions of SOCS1 protein, extracellular signal–regulated kinase, and janus kinase signal transduction and activators of transcription signaling pathways–related proteins were detected using western blotting. After the establishment of subcutaneous xenograft tumor models in nude mice, the latent period, size, volume and growth speed of xenograft tumors in the mock, negative small interfering RNA, and SOCS1-small interfering RNA groups were examined and compared. The results indicated that positive expression rate of SOCS1 was higher in malignant melanoma tissues than in pigmented nevi. MV3 cells had the highest messenger RNA and protein expressions of SOCS1, followed by A357 cells. Compared with the mock and negative small interfering RNA groups, SOCS1-small interfering RNA group showed lower cell viability, elevated cell apoptosis, more cells in G0/G1 phase and less cells in S and G2/M phases, and decreased messenger RNA and protein expressions of SOCS1, p-ERK1/2, p-JAK2, p-STAT1, and p-STAT3. Compared with the mock and negative small interfering RNA groups, the SOCS1-small interfering RNA group showed longer latent period of tumor, smaller tumor size and volume, and smoother tumor growth curve. To conclude, SOCS1 silencing can inhibit proliferation and induce apoptosis of MV3 and A357 melanoma cells in vivo and in vitro by inhibiting extracellular signal–regulated kinase and janus kinase signal transduction and activators of transcription signaling pathways.