Pyrrolidine dithiocarbamate exerts anti-proliferative and pro-apoptotic effects in renal cell carcinoma cell lines

TLDR: The data suggest that pyrrolidine dithiocarbamate has the potential to be an anticancer agent in some forms of RCC.

Abstract: Background. The activation of nuclear factor-kB (NF-kB) has been implicated in the development, progression and metastasis of renal cell carcinoma (RCC). This study investigates the effect of pyrrolidine dithiocarbamate (PDTC), a NF-kB inhibitor, on two metastatic human RCC cell lines, ACHN and SN12K1. Methods. RCC cell lines and normal cells were exposed to 25 or 50mM of PDTC. Apoptosis was measured by flow cytometry and TdT-mediated nick end labelling methods. Cell viability and proliferation were measured by MTT and BrdU assays, respectively. Expression of NF-kB subunits, IkBs, IkB Kinase (IKK) complex and apoptotic regulatory proteins were analysed by western blotting and/or immunofluorescence. DNA-binding activity of NF-kB subunits were measured by ELISA. Results. RCC cell lines had a higher basal level expression of all the five subunits of NF-kB than normal primary cultures of human proximal tubular epithelial cells or HK-2 cells. PDTC decreased the viability and proliferation of RCC, but not normal cells. Of the two RCC cell lines, ACHN had a higher basal level expression of all the five NF-kB subunits than SN12K1 and was more resistant to PDTC. While PDTC induced an overall decrease in expression of all the five NF-kB subunits in both RCC cell lines, unexpectedly, it increased the nuclear expression of NF-kB in ACHN, but not in SN12K1. PDTC reduced the DNA-binding activity of all the NF-kB subunits and the expression of the IKK complex (IKK-a, IKK-b and IKK-g) and the inhibitory units IkB-a and IkB-b. PDTC induced a significant increase in apoptosis in both RCC cell lines. This was associated with a decrease in expression of the anti-apoptotic proteins, Bcl-2 and Bcl-XL, without marked changes in the pro-apoptotic protein Bax. Conclusion. These data suggest that PDTC has the potential to be an anticancer agent in some forms of RCC.