The effects of the nuclear transporter karyopherin alpha2 gene silencing on the cell proliferation and invasion of melanoma cells

Objective To investigate the nuclear transporter karyopherin alpha2 (KPNA2) mRNA expression in melanoma based on the Cancer Genome Atlas (TCGA) database and to further explore the efficacy on proliferation and invasion of melanoma cells after KPNA2 gene silencing.

Methods The TCGA database was used to search the literatures relating KPNA2 mRNA expression level in melanoma tissues and its relationship with prognosis of patients. The co-expressed genes of KPNA2 in melanoma were analyzed by Gene Ontology (GO), Kyoto Encyclopediaof Genes and Genomes (KEGG) enrichment analysis. The expression level of KPNA2 mRNA in the melanoma cell line was detected, and the KPNA2 higher expression cell line A375 was selected. The small interfering RNA was transiently transfected to knock down the expression of KPNA2. The CCK-8, Transwell assay and Western blot methods were used to analyze the efficacy on the proliferation, invasion and phosphorylated P53 (p-P53) protein expression level in melanoma cell line A375 after KPNA2 gene silencing.

Results The relative expression level of KPNA2 mRNA in melanoma tissues were 6.439 (5.800, 6.958), which was significantly higher than 4.035 (1.726, 3.538) in the normal tissues(P < 0.001). The median survival time of KPNA2 high expression patients was 63.9 months, which was lower than 104.6 months in the low expression patients(P=0.011). The KEGG signaling pathway involved in KPNA2 co-expressed genes in melanoma were P53 signaling pathway and cell cycle. The cellular components involved included intercellular bridges, etc., the biological process included the cell cycle, etc., and the molecular function included the origin of DNA replication combine, etc. KPNA2 were expressed in the melanoma cell lines A375, A875 and SK-MEL-28, and with a higher expression in the A375 cell line. Therefore, A375 cells were selected for follow-up study. After KPNA2 gene silencing in melanoma A375 cell line, CCK-8 test results showed that the cell proliferation ability was significantly decreased at 72 h and 96 h (P < 0.05). Transwell results showed that the cell invasion ability was significantly decreased compared with blank control cells and empty cells (P < 0.05). The Western blot results showed that after KPNA2 gene silencing in melanoma A375 cell line, the expression level of p-P53 protein was significantly increased compared with blank control cells and empty cells (P < 0.05).

Conclusion KPNA2 mRNA is significantly over-expressed in melanoma and is associated with poor prognosis of melanoma patients. KPNA2 gene silencing can promote the phosphorylation of tumor suppressor gene P53, thereby regulating the P53 signaling pathway to participate in the proliferation and invasion of melanoma cells.