Prima-1 induces apoptosis in bladder cancer cell lines by activating p53

OBJECTIVES: Bladder cancer represents 3% of all carcinomas in the Brazilian population and ranks second in incidence among urological tumors, after prostate cancer. The loss of p53 function is the main genetic alteration related to the development of high-grade muscle-invasive disease. Prima-1 is a small molecule that restores tumor suppressor function to mutant p53 and induces cancer cell death in various cancer types. Our aim was to investigate the ability of Prima-1 to induce apoptosis after DNA damage in bladder cancer cell lines. METHOD: The therapeutic effect of Prima-1 was studied in two bladder cancer cell lines: T24, which is characterized by a p53 mutation, and RT4, which is the wild-type for the p53 gene. Morphological features of apoptosis induced by p53, including mitochondrial membrane potential changes and the expression of thirteen genes involved in apoptosis, were assessed by microscopic observation and quantitative real-time PCR (qRT-PCR). RESULTS: Prima-1 was able to reactivate p53 function in the T24 (p53 mt) bladder cancer cell line and promote apoptosis via the induction of Bax and Puma expression, activation of the caspase cascade and disruption of the mitochondrial membrane in a BAK-independent manner. CONCLUSION: Prima-1 is able to restore the transcriptional activity of p53. Experimental studies in vivo may be conducted to test this molecule as a new therapeutic agent for urothelial carcinomas of the bladder, which characteristically harbor p53 mutations.

Análise do efeito do Prima-1 na expressão dos genes envolvidos na morte celular programada em linhagens de câncer de bexiga / Analysis of the effect of Prima-1 in the expression of genes involved in programmed cell death in bladder cancer cell lines

Introdução: O carcinoma urotelial de bexiga (CUB) é o segundo tumor mais frequente do trato urinário. A perda da função do p53 é a alteração mais conhecida do carcinoma urotelial de alto grau invasivo. Prima-1 é uma pequena molécula, a qual restaura a função do p53 mutado promovendo a morte celular em vários tipos celulares. O objetivo do nosso estudo foi analisar o efeito do Prima-1 na indução da apoptose mediada por p53 após indução do dano ao DNA em linhagens de CUB. Material e métodos: O mecanismo de ação do Prima-1 foi avaliado em duas linhagens celulares de câncer de bexiga, T24 que tem como característica a mutação do p53 e RT4 que possui p53 intacto. Características morfológicas da apoptose, alterações no potencial de membrana mitocondrial e análise da expressão de treze genes envolvidos na apoptose mediada por p53 foram avaliados através de observação microscópica e reação em cadeia da polimerase em tempo real quantitativa (qRT-PCR). Resultados: Prima-1 foi capaz de reativar a função da P53 na linhagem de câncer de bexiga com p53 mt, promovendo a apoptose através da expressão de Bax e Puma, ativação da cascata das caspases e ruptura da membrana mitocondrial, independente de Bax, na linhagem celular T24 (p53 mt). Conclusão: Prima-1 foi capaz de restaurar a atividade transcricional de p53. Estudos experimentais in vivo poderiam ser conduzidos no intuito de testar essa molécula como um novo agente terapêutico do CUB de alto grau, invasivo, que apresenta caracteristicamente mutação de p53...

Introduction: Urothelial carcinoma of the bladder is the second most common tumor of the urinary tract. Loss of p53 function is the main genetic alteration related to the development of high-grade muscle-invasive disease. Prima-1 is a small molecule that restores tumor suppressor function to mutant p53 and induces cell death in various cancer types. Our aim is to investigate the ability of Prima-1 to induce apoptosis after DNA damage in BC cancer cell lines. Material and Methods: The therapeutic effect of Prima-1 was studied in two BC cell lines, T24, characterized by p53 mutation, and RT4, with no mutation in the p53 gene. Morphological features of apoptosis, mitochondrial membrane potential changes and expression of thirteen genes involved in p53-induced apoptosis were assessed by microscopic observation and quantitative real-time PCR (qRT-PCR) Results: Prima-1 is able to reactivate P53 function in p53-mutated bladder cancer cell line promote apoptosis through the induction of Bax and Puma expression, activating the caspase cascade and disruption of mitochondrial membrane, independent of Bak, in T24 cell line (p53 mt). Conclusion: Prima-1 is able to restore the transcriptional activity of p53. Experimental studies in vivo could be conducted in order to test this molecule as a new therapeutic agent of the urothelial carcinoma of the bladder, which characteristically presents p53 mutation...

Curcumin, but not Prima-1, decreased tumor cell proliferation in the syngeneic murine orthotopic bladder tumor model

OBJECTIVE: Cigarette smoking is the main risk factor for bladder cancer development. Among the mediators of this effect of smoking is nuclear factor-kappa B. Curcumin suppresses cellular transformation by downregulating the activity of nuclear factor-kappa B. Prima-1 is a compound that induces apoptosis in human tumor cells, restoring the function of mutant p53. Our study aimed to evaluate the effects of curcumin and prima-1 in an animal model of bladder cancer. METHODS: Tumor implantation was achieved in six- to eight-week-old female C57BL/6 mice by introducing MB49 bladder cancer cells into the bladder. Intravesical treatment with curcumin and Prima-1 was performed on days 2, 6, 10, and 14. On day 15, the animals were sacrificed. Immunohistochemistry was used to determine the expression of cyclin D1, Cox-2, and p21. Cell proliferation was examined using PCNA. RESULTS: Animals treated with curcumin exhibited a higher degree of necrosis than animals in other groups. Immunohistochemistry showed reduced expression of cyclin D1 in the curcumin-treated group. All of the cells in mice treated with curcumin were p21 positive, suggesting that the p53 pathway is induced by this compound. Prima-1 did not induce any change in tumor size, necrosis, cell proliferation, or the expression of proteins related to the p53 pathway in this animal model. CONCLUSION: Curcumin showed activity in this animal bladder cancer model and probably acted via the regulation of nuclear factor-kappa B and p53. Therefore, curcumin is a good choice for the use in clinical trials to treat superficial bladder cancer as an alternative to bacillus Calmette-Guerin. In contrast, Prima-1 does not seem to have an effect on bladder cancer.