Експресија на стромални маркери и андроген рецептор кај бенигна простатична хиперплазија и простатичен карцином

Abstract

Introduction: The majority of prostate tumors are adenocarcinomas which derive from the epithelial cells that form the prostate glands and prostate ducts. Accordingly, the focuses of investigations so far were genetic alterations of the malignant epithelial cells in the prostate cancer. Recently, there is mounting evidence that alterations in the stromal microenvironment, associated with malignant epithelium could be responsible for the progression of prostatic carcinogenesis. It is hypothesized that in prostate cancer the interactions between the stromal and epithelial compartments are compromised hence alterations are rendered in both epithelial and stromal cells. These alterations contribute to the loss of growth control in epithelial cells that leads to progression of prostate cancer. Aim: The aim of this study is to establish existence of stromal changes in prostatic carcinoma using histochemical and immunohistochemical methods by measuring qualitative changes in the composition of the prostatic stroma in the benign prostatic hyperplasia and prostatic carcinoma and by quantifying and correlating these results. Material and Methods: A retrospective analysis was performed using archived paraffin blocks from samples of 70 cases of radical prostatectomy specimens in which a diagnosis of prostatic carcinoma was made. Adequate samples were chosen from the peripheral zones of prostatic carcinoma in order to correlate them with the surrounding areas of benign prostatic hyperplasia. These samples were stained with the histochemical stain Trichrome Masson and a subsequent immunohistochemical analyses were performed using the antibodies: Vimentin, α-smooth muscle Actin (α-SMA), Desmin and Androgen Receptor (AR). The prostatic stroma was analyzed separately in the zones of benign prostatic hyperplasia and zones of prostatic cancer. First, the staining intensity of the Trichrome Masson stain in the stroma of prostatic carcinoma and stroma of benign prostatic hyperplasia was analyzed and than the expression and the intensity of the signal for the antibodies Vimentin, α-smooth muscle Actin and Desmin in the stroma of prostatic cancer and benign prostatic hyperplasia was analysed. At the end the expression and the intensity of the signal for the antibody Androgen Receptor was analyzed in the epithelial and stromal cells of benign prostatic hyperplasia and prostatic carcinoma. In order to quantify the analyzed data for the histochemical stain Trichrome Masson, the intensity of the staining was evaluated and for the immunohistochemical stains Vimentin, Desmin and α-smooth muscle Actin (α-SMA) a staining index was used that incorporates percentage of stained stromal cells and the intensity of the signal. For Androgen Receptor a histological score was used that measures the distribution and the intensity of the signal and represents the percentage of stained cells for each staining intensity. The data was correlated and an additional correlation was made with the following clinico – pathological parameters: tumor differentiation, local spread of the disease, stage of the disease, patient age and preoperative serum levels of the Prostate Specific Antigen (PSA). For statistical analyses of the data the following methods were used: descriptive methods (average, median), methods of testing significance of differences among analyzed parameters (Chi-square test, Student t test, Wilcoxon matched test, Analysis of Variance, Kruskal-Wallis ANOVA) and methods of determining correlation among designated parameters (Spearman coefficient of rang correlation and Pearson coefficient of correlation). Statistically significant values were determined to be p < 0,05 and highly statistically significant values were determined to be p < 0,01. Results: The histochemical analysis using Trichrome Masson stain showed statistically significant difference (Chi-square = 31,71 df = 1 p < 0,001) in staning intensity which is higher among stromal cells in prostatic carcinoma compared to stromal cells in benign prostatic hyperplasia. The analysis of the immunohistochemical stain with Vimentin antibody showed significantly higher expression (p < 0,001) in the stroma of the prostatic carcinoma compared to the stroma in benign prostatic hyperplasia. In the stroma of the prostatic carcinoma Vimentin expression shows significantly positive correlation with Trichrome Masson histochemical stain (R = 0,68 p < 0,001), with tumor grade (R = 0,35 p = 0,003) and local spread of the disease (R = 0, 28 p = 0,019). The analysis of the immunohistochemical stain with Desmin antibody showed statistically significant (Chi-square = 117,89 df = 1 p < 0,001) lower expression in the stroma of prostatic cancer compared with the stroma in benign prostatic hyperplasia. In the stroma of the prostatic carcinoma Desmin expression shows significantly positive correlation with Trichrome Masson histochemical stain (R = 0,28 p < 0,02) and with tumor grade (R = 0,25 p = 0,035) and local spread of the disease (R = 0, 28 p = 0,019). The analysis of the immunohistochemical stain with α-smooth muscle Actin (α-SMA) antibody did not show statistically significant difference (Chi-square = 0,2 df = 1 p = 0,65 ) in staining intensity between stoma in prostatic carcinoma and stroma in benign prostatic hyperplasia. α-SMA expression in the stroma of prostatic carcinoma significantly correlated only with Gleason score (R = - 0,35 p = 0,005). The analysis of the immunohistochemical stain with Androgen Receptor showed significant lower expression in epithelial cells of prostatic carcinoma compared to epithelial cells of benign prostatic hyperplasia (p = 0,002) and significant lower expression in stromal cells of prostatic carcinoma compared to stromal cells of benign prostatic hyperplasia (p < 0,01). In the prostatic carcinoma a significant positive correlation of Androgen Receptor expression was found between stromal cells of prostatic carcinoma and epithelial cells of prostatic carcinoma (r = 0,46 p < 0,01). The expression of Androgen Receptor showed correlation between the stromal cells of prostatic carcinoma and Gleason score (R = -0,44 p < 0,05). Conclusion: Carcinoma associated reactive stroma shows qualitative and quantitative differences compared to the stroma in benign prostatic hyperplasia with positive staining for the histochemical stain Trichrome Masson, with the emergence of expression of Vimentin antibody and with negative signal for Desmin antibody compatible to the appearance of carcinoma associated myofibroblasts. The amount of reactive stroma and the level of differentiation of the stroma correlate with Gleason grade, T category and stage of the disease which means that scorring of the stromal component of the prostatic carcinoma could represent an additional tool in determination of the aggressiveness of the prostatic carcinoma. The expression of Androgen Receptor is reduced in the epithelial and stromal cells of prostatic carcinoma and the reduction of Androgen Receptor expression in the stromal cells is more pronounced. The expression of Androgen Receptor in stromal cells of prostatic carcinoma significantly correlates with Gleason grade of the tumor meaning that there is significant drop in Androgen Receptor expression in poorly differentiated tumors. Consecutively, the intensity of staining with the histochemical stain Trichrome Masson and the staining index with the immunohistochemical markers Vimentin and Desmin could serve as grading systems for the stroma as a complement to the well established Gleason grading system that analyzes the epithelial component of the prostatic carcinoma. The histological score for Androgen Receptor expression in the stroma of prostatic carcinoma could also serve as an additional grading system to the well established Gleason grading system. The results of this study show that it is necessary in prostatic carcinoma to analyze not only the epithelial but also the stromal component of the tumor since the stroma, as an integral part of prostatic carcinoma, plays a role in initiation and progression of the disease and some of its caracteristics might serve as prognostic factors in the progression of the disease.