Background: EVA1A (Eva-1 homolog A), a novel protein involved in autophagy and apoptosis, functions as a tumor suppressor in some human primary cancers, including hepatocellular carcinoma (HCC). While it is consistently downregulated in several cancers, its involvement in hepatocarcinogenesis is still largely unknown.
Methods: We first detected the expression of EVA1A in HCC tissues and cell lines using RT‒qPCR, immunohistochemistry and western blotting and detected the expression of miR-103a-3p by RT‒qPCR. Then, bioinformatics prediction, dual-luciferase reporter gene assays and western blotting were used to screen and identify the upstream microRNA of EVA1A. After manipulating the expression of miR-103a-3p or EVA1A, wound healing, invasion, proliferation, colony formation, apoptosis, autophagy, mitosis and mitochondrial function assays, including mitochondrial membrane potential, ROS and ATP production assays, were performed to investigate the functions of miR-103a-3p targeting EVA1A in HCC cells. Apoptosis-related proteins were assessed by RT‒qPCR (TP53) or western blotting (TP53, BAX, Bcl-2 and caspase-3). Autophagy level was evaluated by observing LC3 puncta and examining the protein levels of p62, Beclin1 and LC3-II/I.
Results: We found that EVA1A expression was decreased while miR-103a-3p expression was increased in HCC tissues and cell lines and that their expression was inversely correlated in HCC patients. The expression of miR-103a-3p was associated with HCC tumor stage and poor prognosis. miR-103a-3p could target EVA1A through direct binding to its 3'-UTR and suppress its expression. Overexpression of miR-103a-3p significantly downregulated the expression of EVA1A, TP53 and BAX, upregulated the JAK2/STAT3 pathway and promoted HCC cell migration, invasion and proliferation, while repression of miR-103a-3p dramatically upregulated the expression of EVA1A, TP53, BAX and cleaved-caspase-3, inhibited HCC cell migration, invasion and proliferation, and caused mitochondrial dysfunction and apoptosis. Overexpression of EVA1A significantly attenuated the cancer-promoting effects of miR-103a-3p in HCC cells, while knockdown of EVA1A alleviated the mitochondrial dysfunction and apoptosis caused by miR-103a-3p inhibition. Overexpression of EVA1A did not induce significant changes in autophagy levels, nor did it affect G2/M transition or mitosis.
Conclusion: These findings indicate that the downregulation of the tumor suppressor EVA1A by miR-103a-3p potentially acts as a key mediator in HCC progression, mainly by inhibiting apoptosis and promoting metastasis. The miR-103a/EVA1A/TP53 axis provides a new potential diagnostic and therapeutic target for HCC treatment.
Keywords: Apoptosis; Autophagy; EVA1A; Mitosis; TP53; hepatocellular carcinoma; miR-103a-3p.
© 2022. The Author(s).