Insulin Induced Down Regulation of the Progesterone Receptor Number in Neutrophils in the Synthesis of Maspin in Breast Cancer

Abstract

Purpose: The binding of either progesterone or insulin to their specific receptors on neutrophils has been reported to stimulate nitric oxide (NO) induced maspin synthesis in these cells. Experiments were carried out to determine the role of progesterone receptor interaction in the nitric oxide induced maspin synthesis in neutrophils that was preincubated with insulin. Methods: progesterone receptor positive (PR+), progesterone receptor negative (PR-) neutrophils were isolated from the blood cancer subjects. Maspin was determined by enzyme linked immunosorbent assay after in vitro translation of maspin mRNA. NO was determined by methemoglobin method. Results: Immunohistochemical studies of progesterone receptor (PR) demonstrated the presence of progesterone receptor in the normal peripheral neutrophils and less in number in PR+ breast cancer neutrophils. In contrast, PR-breast cancer neutrophils lacked the progesterone receptor, suggesting pathophysiological defects in the synthesis of PR protein in peripheral PRneutrophils. It was also found that as a result of incubation of neutrophils with insulin the binding affinity for progesterone to its receptor in normal neutrophils remained essentially unchanged which demonstrated Kd = 47.619 nM compared to Kd of the binding of progesterone is 46.08 nM in the normal neutrophils that were not pretreated with insulin. The progesterone receptors which were 11.5×10 10 /cell in the untreated cells was found to be decreased to 8.2×10 10 /cell (p<0.005, n=6) after the same cell were treated with 200µU of insulin. The reduction of PR number on normal neutrophils due to the pretreatment with insulin resulted in the decreased NO induced maspin synthesis from 2.329 ± 0.012 nM to 1.410 ± 0.002 nM. Decreased PR number in PR+ breast cancer neutrophils due to disease condition and pretreatment with insulin reduced the maspin synthesis from 1.138 ± 0.024 nM to 0.555 ± 0.003 nM compared to normal control. Conclusion: These results suggested that insulin down regulated maspin synthesis in normal and in breast cancer neutrophils by decreasing the progesterone receptor number in both cases.

Multiomic immune clockworks of pregnancy

“…Progesterone—which rises throughout human pregnancy before dipping slightly prior to parturition—is a keystone pacemaker for pregnancy [ 51 , 125 , 185 ]. Progesterone influences the pregnancy timeline through its immunomodulatory activity, which is mediated via four main mechanisms: (1) direct communication with immune cells via its nuclear receptors, progesterone receptor (PR)-B and PR-A, (2) signaling through its membrane progesterone receptors (mPR), (3) promiscuous binding to the glucocorticoid receptor, and/or (4) inducing transcription of the paracrine hormone Progesterone Induced Blocking Factor (PIBF) [ 10 , 12 , 14 , 15 , 92 , 122 , 132 , 172 ]. Although progesterone’s role in the immune system remains an area of investigation, the general consensus is that, at least up until the time of parturition, progesterone is a critical factor in the maintenance of an immunotolerant state and of myometrial quiescence.…”