T-type Ca2+ channels and their relationship with pre-neoplastic and neoplastic lesions in the human breast

Abstract

The expression of T-type voltage-dependent Ca2+ channels (Cav3) has been previously observed in breast cancer, but their expression and subcellular localization were not evaluated in pre-neoplastic lesions. Therefore, this work aimed to evaluate protein expression and subcellular localization of T-type channel isoforms in human breast tissue samples. Protein expressions of CaV3.1, CaV3.2, and CaV3.3 were evaluated by immunohistochemistry in breast without alteration, in proliferative non-neoplastic lesions, and in neoplastic ductal epithelial lesions of the human breast. CaV3.1, CaV3.2, and CaV3.3 nuclear expressions were decreased in advanced stages of neoplastic transformation, whereas CaV3.1 and CaV3.2 cytoplasmic expression increased. Also, the decrease in nuclear expression was correlated with an increase in cytoplasmic expression for CaV3.1 isoform. The change in CaV3 protein expression and subcellular localization are consistent with the neoplastic transformation stages of mammary epithelial cells, evident in early neoplastic lesions, such as ductal carcinomas in situ. These results suggest a possible involvement of CaV3 in the carcinogenic processes and could be considered as a potential pharmacological target in new therapies for breast cancer treatment.

Figure 1. Classification of histological types. Mammary glands, stained with hematoxylin and eosin (400× magnification, scale bar, 50 µm). A, Breast without alteration; (B) ductal hyperplasia; (C) ductal carcinoma in situ; (D) invasive ductal carcinoma.

Figure 2. Human mammary glands with immunohistochemical staining for Ca_V3.1 identified by DAB chromogen staining and hematoxylin counterstaining (main image 400× magnification, insert 600× magnification; scale bar, 50 µm). A, Breast without alteration showing nuclear expression (arrow) and absence of cytoplasmic immunostaining. B, Ductal hyperplasia with nuclear immunostaining (arrow). C, Ductal carcinoma in situ showing decreased nuclear expression and presence of cytoplasmic expression (arrow). D, Invasive ductal carcinoma with few nuclear immunostainings and cytoplasmic expression (arrow). Statistical test: Pearson’s correlation coefficient.

Figure 3. Human mammary glands with immunohistochemical staining for Ca_V3.2 identified by DAB chromogen staining and hematoxylin counterstaining (main image 400× magnification and insert 600× magnification; scale bar, 50 µm). A, Breast without alteration showing nuclear expression (arrow) and no cytoplasmic immunostaining. B, Ductal hyperplasia with nuclear expression (arrow). C, Ductal carcinoma in situ showing decreased nuclear expression and cytoplasmic immunostaining (arrow). D, Invasive ductal carcinoma with few nuclear immunostainings and cytoplasmic expression (arrow). Statistical test: Pearson’s correlation coefficient.

Figure 4. Human mammary glands with immunohistochemical staining for Ca_V3.3 identified by DAB chromogen staining and hematoxylin counterstaining (main image 400× and insert 600× magnification; scale bar, 50 µm). A, Breast without alteration showing nuclear expression (arrow) and no cytoplasmic immunostaining. B, Ductal hyperplasia with nuclear expression (arrow). C, Ductal carcinoma in situ showing decreased nuclear expression and cytoplasmic expression (arrow). D, Invasive ductal carcinoma with few nuclear immunostainings and cytoplasmic expression (arrow). Statistical test: Pearson’s correlation coefficient.