Intracellular aggregated TRPV1 is associated with lower survival in breast cancer patients.

Abstract

BackgroundBreast cancer is a malignant disease that represents an important public health burden. The description of new molecular markers can be important to diagnosis, classification, and treatment. Transient receptor potential vanilloid 1 (TRPV1) polymodal channel is expressed in different neoplastic tissues and cell lines of breast cancer and associated with the regulation of tumor growth, tumor neurogenesis, cancer pain, and malignant progression of cancer. In primary and metastatic breast cancer tumors, TRPV1 is expressed during neoplastic transformation, invasive behavior, and resistance to cytotoxic therapy.ObjectiveThe objective of this study was to describe the subcellular distribution of TRPV1 in invasive breast carcinomas and its association with survival.MethodsIn 33 cases of invasive breast carcinomas, we identified immunohistochemical and immunofluorescent expression patterns of TRPV1 compared to healthy breast tissue. We characterized the expression of TRPV1 induced by estrogens in breast cancer cell lines MCF-7 and MDA to establish a model of the TRPV1–estrogen relationship regarding the malignant potential. We examined the association of TRPV1 patterns with patients’ survival with the Kaplan–Meyer model, using the log-rank test at 5 years of follow-up. The relation of TRPV1 expression patterns to the St. Gallen breast cancer subtypes was also tested.ResultsBased on immunohistochemical expression pattern of TRPV1, we distinguished two main categories of breast cancer tissue, a “classical category” that exhibited diffuse expression of the channel and a “non-classical category” that expressed the channel in aggregates at the ER/Golgi and/or surrounding these structures. The classical pattern of TRPV1 was associated with a higher survival rate. In breast cancer cell lines, increasing doses of estrogens induced increased TRPV1 expression with nonclassical patterns at higher doses via a mechanism dependent on ER α.ConclusionThe expression and distribution of TRPV1 in invasive breast carcinomas may be considered as a biomarker for prognosis of the disease and a probable therapeutic target.