ZNF23 Suppresses Cutaneous Melanoma Cell Malignancy via Mitochondria-Dependent Pathway

Cutaneous melanoma is one of the leading causes of cancer deaths with an increasing incidence worldwide. A KRAB-containing zinc finger protein member, zinc finger 23 (ZNF23), was reduced in some types of tumors and inhibited cell growth by inducing cell cycle arrest. However, the role of ZNF23 expression is still poorly understood in melanoma.

The level of ZNF23 expression was detected in cutaneous melanoma, adjacent normal skin tissues and cutaneous melanoma cell lines using immunohistochemistry and western blotting. The correlations between ZNF23 expression and other clinicopathologic parameters were analyzed in melanoma patients. Ectopic expression of ZNF23 plasmid was transfected into melanoma cells, SK-MEL-1 and SK-MEL-28. MTT, flow cytometry and transwell assay were used to measure cell proliferation, apoptosis, invasion and migration abilities, respectively. Mitochondrial functions and structures were detected by mitochondrial membrane potential assay and Transmission electron microscopy (TEM) method in melanoma cells transfected with overexpressing ZNF23 plasmid or empty vector. Western blotting was performed to detect the levels of ZNF23, p53, p27, Bcl-2 and cleaved caspase-3 after overexpressing of ZNF23 in melanoma cells.

ZNF23 was elevated in adjacent normal skin tissues compared with melanoma tissues. Patients with low level of ZNF23 expression exhibited higher incidence of lymphoid metastasis, thicker size of tumors and worse outcome. By using Cox's regression analysis, ZNF23 expression, tumor thickness and lymph node metastasis were the independent prognostic factors for overall survival (p < 0.05). Results from cellular experiments indicated that ectopic expression of ZNF23 induced cell apoptosis by activation of caspase-3, p27, p53 expression and down-regulation of Bcl-2 through mitochondria-dependent pathway.

Decreased ZNF23 was contributed to melanoma progression and poor survival with mitochondria-dependent pathway. It indicated that ZNF23 could be a promising therapeutic biomarker candidate for cutaneous melanoma.