Abstract:

Objective To discuss the effect of curcumin on the proliferation， migration， and invasion of the human prostate cancer C4-2 and LNCaP cells， and to clarify its possible mechanism. Methods The lentiviral transfection system was used to transfect the C4-2 and LNCaP cells， regarded as shCD147-C4-2 group and shCD147-LNCaP group. RNA interference technology was used to prepare the CD147-silenced cells； the cells transfected with an empty vector were regarded as negative control and divided into shNC-C4-2 group （shNC-C4-2 cells） and shNC-LNCaP group （shNC-LNCaP cells）. The C4-2 and LNCaP cells at logarithmic growth phase， as well as shCD147-C4-2 and shCD147-LNCaP cells， were treated with 20 μmol·L^-1 curcumin.The morphology of the cells in various groups was observed under microscope at 0 and 24 h of treatment； MTT method was used to detect the proliferation activities of the cells in various groups； cell scratch assay was used to detect the migration rates of the cells in various groups；Western blotting method was used to detect the expression levels of apoptosis， invasion， and migration-related proteins in the cells in various groups. Results Compared with C4-2 group， the expression of CD147 protein in the cells in shCD147-C4-2 group was significantly decreased after CD147 gene silenting.Compared with LNCaP group， the expression level of CD147 protein in the cells in shCD147-LNCaP group was significantly decreased after CD147 gene silenting. Compared with 0 h of treatment， some cells in C4-2 and LNCaP groups after 24 h of treatment with 20 μmol·L^-1 curcumin， showed apoptosis signs with the presence of typical apoptotic bodies. The apoptotic phenomena in shCD147-C4-2 and shCD147-LNCaP groups was reduced.The MTT assay results showed that compared with C4-2+0 μmol·L^-1 curcumin group， the proliferation activities of the cells in C4-2+20 μmol·L^-1 curcumin group， C4-2+40 μmol·L^-1 curcumin group， C4-2+60 μmol·L^-1 curcumin group， and C4-2+80 μmol·L^-1 curcumin group were decreased （P<0.01）. Compared with LNCaP+0 μmol·L^-1 curcumin group， the proliferation activity of the cells in LNCaP+20 μmol·L^-1 curcumin group， LNCaP+ 40 μmol·L^-1 curcumin group， LNCaP+60 μmol·L^-1 curcumin group， and LNCaP+80 μmol·L^-1 curcumin group were decreased （P<0.01）. Compared with shNC-C4-2 group， the proliferation activity of the cells in shNC-C4-2+20 μmol·L^-1 curcumin group was decreased （P<0.01）. Compared with shNC-C4-2+20 μmol·L^-1 curcumin group， the proliferation activity of the cells in shCD147-C4-2+20 μmol·L^-1 curcumin group was increased （P<0.01）. Compared with shNC-LNCaP group， the proliferation activity of the cells in shNC-LNCaP+20 μmol·L^-1 curcumin group was decreased （P<0.01）； compared with shNC-LNCaP+20 μmol·L^-1 curcumin group， the proliferation activity of the cells in shCD147-LNCaP+20 μmol·L^-1 curcumin group was significantly increased （P<0.01）. The cell scratch healing assay results showed that compared with C4-2 group， the migration rates of the cells in C4-2+20 μmol·L^-1 curcumin group and C4-2+40 μmol·L^-1 curcumin group after 24 h of treatment were decreased （P<0.01）； compared with LNCaP group， the migration rates of the cells in LNCaP+20 μmol·L^-1 curcumin group and LNCaP+40 μmol·L^-1 curcumin group were increased（P<0.01）； compared with shNC-C4-2 group， the migration rate of the cells in shNC-C4-2+20 μmol·L^-1 curcumin group was decreased （P<0.01）； compared with shNC-C4-2+20 μmol·L^-1 curcumin group， the migration rate of the cells in shCD147-C4-2+20 μmol·L^-1 curcumin group was significantly increased （P<0.05）； compared with shNC-LNCaP group， the migration rate of the cells in shNC-LNCaP+20 μmol·L^-1 curcumin group was decreased （P<0.01）； compared with shNC-LNCaP+20 μmol·L^-1 curcumin group， the garation rate of the cells in shCD147-LNCaP+20 μmol·L^-1 curcumin group was significantly increased （P<0.05）.The Western blotting results showed that compared with C4-2 group， the expression levels of Bcl-2-associated X protein （Bax）， cleaved Caspase-3， and poly ADP-ribose polymerase 1 （PARP1） proteins in the cells in C4-2+20 μmol·L^-1 curcumin group and C4-2+40 μmol·L^-1 curcumin group were significantly increased （P<0.01）， and the expression levels of Bcl-2 protein was significantly decreased （P<0.05 or P<0.01）； compared with LNCaP group， the expression levels of Bax， cleaved Caspase-3， and PARP1 proteins in the cells in LNCaP+20 μmol·L^-1 curcumin group and LNCaP+40 μmol·L^-1 curcumin group were significantly increased （P<0.01）， and the expression level of Bcl-2 protein in the cells in LNCaP+40 μmol·L^-1 curcumin group was decreased （P<0.01）； compared with shNC-C4-2 group， the expression levels of Bax， cleaved Caspase-3， and PARP1 proteins in the cells in shNC-C4-2+20 μmol·L^-1 curcumin group were significantly increased （P<0.05 or P<0.01）， and the expression level of Bcl-2 protein was significantly decreased （P<0.05）； compared with shNC-C4-2+20 μmol·L^-1 curcumin group， the expression levels of Bax and cleaved Caspase-3 proteins in the cells in shCD147-C4-2+20 μmol·L^-1 curcumin group were significantly decreased （P<0.01）； compared with shNC-LNCaP group， the expression levels of Bax， cleaved Caspase-3， and PARP1 proteins in the cells in shNC-LNCaP+20 μmol·L^-1 curcumin group were significantly increased （P<0.05 or P<0.01）， and the expression level of Bcl-2 protein was significantly decreased （P<0.05）； compared with shNC-LNCaP+20 μmol·L^-1 curcumin group， the expression levels of Bax， cleaved Caspase-3， and PARP1 proteins in the cells in shCD147-LNCaP+20 μmol·L^-1 curcumin group were significantly decreased （P<0.05 or P<0.01）， and the expression level of Bcl-2 protein was significantly increased （P<0.05）. Compared with C4-2 group， the expression levels of E-cadherin protein in the cells in C4-2+20 μmol·L^-1 curcumin group and C4-2+40 μmol·L^-1 curcumin group were significantly increased （P<0.01）， and the expression levels of N-cadherin and Vimentin proteins were significantly decreased （P<0.01）； compared with LNCaP group， the expression levels of E-cadherin protein in the cells in LNCaP+20 μmol·L^-1 curcumin group and LNCaP+40 μmol·L^-1 curcumin group were significantly increased （P<0.01）， and the expression levels of N-cadherin and Vimentin proteins in the cells in LNCaP+40 μmol·L^-1 curcumin group were significantly decreased （P<0.01）； compared with shNC-C4-2 group， the expression levels of N-cadherin and Vimentin proteins in the cells in shNC-C4-2+20 μmol·L^-1 curcumin group were significantly decreased （P<0.01）； compared with shNC-C4-2+20 μmol·L^-1 curcumin group， the expression level of E-cadherin protein in the cells in shCD147-C4-2+20 μmol·L^-1 curcumin group was significantly decreased（P<0.01）， and the expression levels of N-cadherin and Vimentin proteins were significantly increased （P<0.01）； compared with shNC-LNCaP group， the expression level of E-cadherin protein in the cells in shNC-LNCaP+20 μmol·L^-1 curcumin group was significantly increased （P<0.01）， and the expression levels of N-cadherin and Vimentin proteins were significantly decreased （P<0.01）； compared with shNC-LNCaP+20 μmol·L-1 curcumin group， the expression level of E-cadherin protein in the cells in shCD147-LNCaP+20 μmol·L^-1 curcumin group was significantly decreased （P<0.01）， and the expression level of N-cadherin was significantly increased （P<0.05）. Conclusion Curcumin inhibits the proliferation， migration， and invasion of the prostate cancer cells in vitro and induces the apoptosis； silencing the CD147 gene partially reduces its inhibitory effect and its ability to induce the apoptosis.

Key words: Curcumin, CD147, Prostate neoplasm, Cell invasion, Cell migration