Introduction:
This study aimed to investigate the effects of the lncRNA PCA3 in colon cancer and the associated mechanisms.

Material and methods:
Adjacent normal and cancer tissues were collected from colon cancer patients, and their PCA3 expression was measured by ISH and RT-qPCR assays. The correlations of PCA3 with clinical pathology and prognosis were also analysed. In addition, PCA3 and si-PCA3 were transfected into colon cancer cells (HT-29 and SW620). Moreover, cell proliferation, apoptosis, number of invading cells, and wound healing rate were determined by MTT, flow cytometry, Transwell, and wound healing assays. The relative protein expression was evaluated by western blotting.

Results:
Compared with that in normal tissues, PCA3 expression was significantly increased in colon cancer (p < 0.001). High PCA3 expression was correlated with malignant pathology and poor prognosis in patients. Compared with that in HCoEpic cells, PCA3 gene expression was significantly upregulated in SW480, HT-29, SW620, and HCT116 cells (all p < 0.01). With PCA3 transfection, cell proliferation increased, apoptosis decreased, and the number of invading cells and wound healing rate increased. In addition, RhoC, Bcl-2 and MMP-2 proteins increased, while Bax was suppressed. With the transfection of si-PCA3, which knocked down PCA3 expression, cell proliferation decreased, apoptosis increased, and the number of invading cells and wound healing rate decreased. Furthermore, RhoC, Bcl-2, and MMP-2 proteins decreased, while Bax increased.

Conclusions:
PCA3 is an oncogene in colon cancer. In vitro analysis indicates that knockdown of PCA3 suppresses the biological activities of colon cancer cells via the regulation of RhoC.