Calcium-binding and coiled-coil domain 2 promotes the proliferation and suppresses apoptosis of prostate cancer cells.

Prostate cancer (PCa) is considered to be one of the most common tumors in men. Calcium-binding and coiled-coil domain 2 (CALCOCO2) is a known important xenophagy receptor, which mediates intracellular bacterial degradation. To the best of the authors' knowledge, the present study is the first to demonstrate that CALCOCO2 functions as an oncogene in PCa. The results of the current study indicated that CALCOCO2 knockdown suppressed cell proliferation and colony formation, whereas it promoted apoptosis of PCa cells. In addition, knockdown of CALCOCO2 in PCa cells reduced cyclin-E1 and increased p53 protein expression. Bioinformatics analysis revealed that CALCOCO2 was associated with 'autophagosome assembly', 'nucleophagy' and 'nucleic acid metabolic process' biological processes and interacted with sequestosome-1, microtubule-associated proteins 1A/1B light chain 3 (MAP1LC3)B, γ-aminobutyric acid receptor-associated protein, IκB kinase subunit γ and MAP1LC3C. Moreover, CALCOCO2 protein levels were indicated to be significantly increased in PCa samples compared with normal prostate tissues. These results suggested that CALCOCO2 may be of value as a diagnostic and therapeutic target in PCa.