Expression of pannexin familly of gap junction proteins in invasive ductal breast carcinoma

Breast cancer (BC) is the most prevailing malignancy among worldwide female population, with constantly increasing incidence and serious consequences on morbidity and mortality of affected patients. Genotypically and phenotypically BCs represent very heterogeneous group of tumours, diverse in their pathohistological features, expression of molecular markers, malignant/metastatic potential, clinical presentation, prognosis, and response to therapy. The purpose of this preliminary study was to determine the expression pattern of pannexin family (Panx 1/2/3) of gap junction proteins in invasive ductal breast carcinoma. A total of 27 female patients with diagnosed invasive ductal BC were included in the study. All cases were graded according to the modified criteria of Scarff Bloom-Richardson, as described by Elston and Ellis. Tumour tissue samples surgically removed from each patient (primary tumor and positive axillary lymph nodes) were embedded in paraffin blocks for immunohistological staining or snap- frozen in liquid N2 for RNA isolation. Immunohistochemical staining was performed with rabbit polyclonal anti-human pannexin-1, 2 and 3 antibody (AbCam ab78380, ab55917, ab98093) using DAB substrate and HRP reaction. RNA isolation, in vitro transcription and qRT-PCR were performed using TRI Reagent and RNeasy Mini kit, gene specific Quanti Tect Primer Assay (Qiagen) and 7500 qRT-PCR system (Applied Biosystem). Obtained results showed positive (protein, mRNA) expression pattern ranging from diffuse (Panx2) to granular (Panx1, Panx3) cytoplasmatic staining with slight or no membrane positivity in tumor cells of all analyzed samples. However, the significance, if any, of their expression for tumorigenesis of invasive ductal breast carcinoma has still to be elucidated.