Expression of MUC1 protein in invasive pituitary adenomas and its role in anti-tumor immune response

Abstract

Objective To investigate the MUC1 protein expression in invasive and non-invasive pituitary adenomas and its induction role in antitumor immune responses. Methods Eighty-six glioma specimens, collected at the resection surgery in our hospitals from March 2009 to December 2014, were used as experimental subjects, including 42 of invasive pituitary adenomas and 44 of non-invasive pituitary adenomas; the MUC1 protein expression was detected by immunohistochemical staining and Western blotting. Before the resection surgery, 400 mL peripheral blood was collected to separate peripheral blood mononuclear cells (PBMCs) and induce dendritic cells (DCs). (1) The DCs were divided into MUC1 group, 5 μg/mL poly I:C group, 25 μg/mL poly I:C group, 50 μg/mL poly I: C group, lipopolysaccharide (LPS) group and control group, and 100 μL 50 μg/mL MUC1, 5 μg/mL poly I:C, 25 μg/mL poly I:C, 50 μg/mL poly I:C, and 50 μg/mL LPS and 100 μL solvent were given to the above groups; 48 h after the culture, ELISA was employed to detect the concentrations of tumor necrosis factorα(TNFα), interleukin (IL)-1β and IL-6. (2) The DCs were divided into PBS control group, poly I:C group and MUC1+poly I:C group, and 100 μL PBS, 50 μg/mL poly I:C and 50 μg/mL MUC1+50 μg/mL poly I:C were added, respectively; 48 h after the culture, flow cytometry (FCM) was employed to detect the CD40, CD80, CD83, CD14 and histocompatibility genetic locus antigen DR (HLA-DR) expressions. (3) Twenty-four C57BL/6 mice were randomly divided into MUC1 group, MUC1+ poly I:C and PBS control group (n=8); subcutaneous injection of 1 mL 50 μg/mL MUC1 antigen, 50 μg/mL MUC1 antigen+50 μg/mL poly I:C and PBS was given to the above three groups on the first and 15th d; 7 d after injection, spleen cytotoxic T lymphocytes (CTLs) from the above three groups were extracted and added into the pituitary adenoma cells AtT20, and D-lactate dehydrogenase (D-LDH) ELISA was used to detect the killing activity of CTLs. Results The positive rate of MUC1 protein expression in the invasive pituitary adenomas and non-invasive pituitary adenomas was 90.4% (38/42) and 20.5% (9/44), with significant difference (P<0.05); MUC1 protein expression in the invasive pituitary adenomas (2.0353±0.0359) was significantly higher than that in the non-invasive pituitary adenomas (0.3488±0.0205,P<0.05). ELISA indicated that concentrations of TNFα, IL-1β and IL-6 in the supernate of DCs from MUC1 group, 5 μg/mL poly I:C group, 25 μg/mL poly I:C and 50 μg/mL poly I:C group were increased in sequence, with significant differences between the two groups (P< 0.05). FCM indicated that the CD14 expression was decreased accordingly, and CD40, CD80, CD83 and HLA-DR expressions were increased accordingly in DCs from PBS control group, poly I:C group and MUC1+poly I:C group, with significant difference (P<0.05); killing activity of CTLs in the PBS control group, MUC1 group and MUC1+poly I:C group was increased accordingly, with significant differences (P<0.05). Discussion MUC1 protein can highly express in the invasive pituitary tumors; MUC1+ poly I:C can effectively induce antitumor immune response, thereby inhibiting the development of invasive pituitary tumors Key words: Invasive pituitary adenoma; MUC1 protein; Poly I:C; Dentritic cell