Effect of diabetes on biodistribution, nephrotoxicity and antitumor activity of cisplatin in mice.

Both types of diabetes are associated with higher incidence of some types of cancer. Treating cancer in diabetic patients without aggravating diabetes-related complications is a challenge for clinicians. Additionally, little is known about how diabetes affects the treatment of cancer. One of the most effective chemotherapeutic drugs is cisplatin, which is nephrotoxic. Studies suggest that diabetes acts as a protective factor against the nephrotoxicity of cisplatin, but the mechanisms involved have not been elucidated yet. This renal protection has been attributed to decreased accumulation of cisplatin in the kidneys, which could be associated with deficient active transport of proximal tubular cells or to pharmacokinetic alterations caused by diabetes. However, it is uncertain if diabetes also compromises the antitumor activity of cisplatin. To address this issue, we developed a mouse model bearing cisplatin-induced nephrotoxicity, Sarcoma 180 and streptozotocin-induced diabetes. Four groups of treatment were defined: (i) control, (ii) diabetic, (iii) cisplatin and (iv) diabetic treated with cisplatin. The following parameters were evaluated: renal function, oxidative stress, apoptosis, renal histopathology, tumor remission, survival rate, genotoxicity and platinum concentration in tumor and several organs. Results indicate that diabetes protects against the renal damage induced by cisplatin, while also compromises its antitumor effectiveness. This is the first study to demonstrate this effect.

Carvedilol efficiently protects kidneys without affecting the antitumor efficacy of cisplatin in mice.

Cisplatin is an effective anticancer drug which has been used to treat a wide range of tumors for the last 30 years. However, its use is associated with nephrotoxicity. Protective strategies have been reported, but their impact on the antitumor activity of cisplatin has not been clarified. We have previously reported the protective potential of carvedilol against cisplatin nephrotoxicity in tumor-free rats. Therefore, in the present study we used a tumor-bearing model to investigate the impact of carvedilol on the antitumor activity of cisplatin. The renal damage induced by cisplatin and the protective effect of carvedilol were demonstrated by the levels of blood urea nitrogen and plasma creatinine as well as by renal histopathology and immunohistochemistry. The mechanism of protection was associated with significantly decreased (i) oxidative stress markers, (ii) Bax expression, (iii) caspase-3 activity and (iv) TUNEL labeling for apoptosis. More importantly, evaluation of tumor mass, tumor remission rate and the survival curve showed that carvedilol did not impair the antitumor action of cisplatin. These findings suggest that the mechanisms underlying the nephrotoxic and the antitumor activity of cisplatin might be different. This is the first study to report such findings. Compared to other reported potential cytoprotectors against cisplatin-induced nephrotoxicity, carvedilol stands out due to the fact that it is already clinically-employed and well tolerated by the patients. Based on these features and on the present findings, carvedilol is a very promising candidate for future clinical trials as nephroprotector in patients treated with cisplatin.