Regulation of expression of the multidrug resistance protein MRP1 by p53 in human prostate cancer cells
Gregory F. Sullivan, Jin-Ming Yang, Andrew Vassil, Jun Yang, Judy Bash-Babula, William N. Hait
Gregory F. Sullivan, Jin-Ming Yang, Andrew Vassil, Jun Yang, Judy Bash-Babula, William N. Hait
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Regulation of expression of the multidrug resistance protein MRP1 by p53 in human prostate cancer cells

Abstract

The expression of several drug-resistance genes, including MRP and p53, increases with advancing stage of human prostate cancer. Altered transcription could account for the genotypic alterations associated with prostate cancer progression, and it was recently reported that the promoter of MRP1 is activated in the presence of mutant p53. To determine whether there is a relationship between p53 status and the expression of MRP1, a human, temperature-sensitive p53 mutant (tsp Val138) was transfected into LNCaP human prostate cancer cells. In the transfected cell line (LVCaP), the wild-type p53 produced growth arrest at the G1/S interface of the cell cycle, inhibited colony formation, and induced p21waf1/cip1. Temperature shifting to 38°C (p53 mutant) produced a time-dependent increase in expression of MRP1. This change in MRP1 expression was also seen in isogenic cell lines in which p53 was inactivated by human papilloma virus (HPV)16E6 protein or by a dominant-negative mutant. Functional assays revealed a decrease in drug accumulation and drug sensitivity associated with mutant p53 and increased MRP1 expression. These results provide the first mechanistic link between expression of MRP1 and mutation of p53 in human prostate cancer and support recent clinical associations. Furthermore, these data suggest a mechanism tying accumulation of p53 mutations to the multidrug resistance phenotype seen in this disease.

Authors

Gregory F. Sullivan, Jin-Ming Yang, Andrew Vassil, Jun Yang, Judy Bash-Babula, William N. Hait

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Leukotriene C4 accumulation in LNCaP and LVCaP cells. Cells seeded in 24...
Leukotriene C4 accumulation in LNCaP and LVCaP cells. Cells seeded in 24-well plates were grown at 37°C (LNCaP) or 32°C (LVCaP). When cells were 80% confluent, LVCaP cells were shifted to 38°C and incubated for 60 hours. Cells were then incubated with [3H]leukotriene C4 for 2 hours at 37°C (LNCaP) or 38°C (LVCaP). At the end of incubation, cells were cooled on ice, washed three times with ice-cold PBS, and solubilized with 0.25 mL of 1% SDS. The radioactivity in each sample was determined by scintillation counting. (a) Comparison of leukotriene C4 accumulation in LVCaP to that in LNCaP cells grown at 38°C. (b) Comparison of leukotriene C4 accumulation in LVCaP cells grown at 32°C to that in the same cells grown at 38°C.