Expressão da leptina e seu receptor no câncer de próstata

Abstract

Prostate cancer is the most common non-cutaneous tumor among men and accounted for the second highest mortality rate among tumors in this sex. Different methods are used to determine the prognosis of patients with prostate cancer, yet there is great heterogeneity when they are used individually. Leptin is a peptide hormone, involved in the regulation of food intake, metabolism, energy expenditure, and neuroendocrine function. This hormone appears to be involved in the pathogenesis of some types of tumors, including prostate adenocarcinomas. Up to the present, it is uncertain if leptin and its receptor may be used as prognostic factors in prostate cancer. The objective of this study was correlate the profiles of immunostaining of leptin and its receptor in prostate adenocarcinomas with different prognostic factors and compare the analysis of immunostaining of leptin and its receptor in prostate adenocarcinomas by semi quantitative and quantitative methods (morphometry). A total of 532 surgical specimens from radical prostatectomies from prostate cancer had been studied. After pathological examination, these samples were included in a tissue microarray containing fragments of tumoral and non-tumoral areas (peritumoral areas). These were immunostained with antibodies antileptin and antileptin receptor. Subjective analysis (made by two observers) and objective (by counting points) were performed on each sample. These results were compared and correlated with the following prognostic factors: perineural invasion, neoplasic vascular embolization, bilateral involvement of the prostate, seminal vesicle invasion, involvement of vesical margin, involvement of urethral margin and involvement of resection surgical margin. There were significant differences between subjective analyses of the two observers, and, therefore, they were not used for other comparisons. Regarding the objective analysis, it was found that leptin receptor expression was reduced in tumors with involvement of the surgical margin, urethral margin and seminal vesicles invasion. Further, there were correlation between the expression of this receptor and the sum of prognostic factors. For the other analyses, it was not observed any significant difference. Semi quantitative methods can have great variation and should be passed over in relation to quantitative methods for the analysis performed in this study. Neither leptin nor its receptor exhibited changes in their expression in neoplastic prostatic samples compared to those that are not neoplastic. The leptin receptor showed a decreased expression in tumors with positive surgical margin, positive urethral margin and involvement of seminal vesicles. There were a negative correlation between the percentage of immunostaining area with antibody antileptin receptor and the sum of prognostic factors.