The impact of progesterone and RU-486 on classic pro-labour proteins & contractility in human myometrial tissues during 24-hour exposure to tension & interleukin-1β

Evaluating aminophylline and progesterone combination treatment to modulate contractility and labor-related proteins in pregnant human myometrial tissues

Progesterone (P4) and cyclic adenosine monophosphate (cAMP) are regarded as pro-quiescent factors that suppress uterine contractions during pregnancy. We previously used human primary cells in vitro and mice in vivo to demonstrate that simultaneously enhancing myometrial P4 and cAMP levels may reduce inflammation-associated preterm labor. Here, we assessed whether aminophylline (Ami; phosphodiesterase inhibitor) and P4 can reduce myometrial contractility and contraction-associated proteins (CAPs) better together than individually; both agents are clinically used drugs. Myometrial tissues from pregnant non-laboring women were treated ex vivo with Ami acutely (while spontaneous contracting) or throughout 24-h tissue culture (±P4); isometric tension measurements, PKA assays, and Western blotting were used to assess tissue contractility, cAMP action, and inflammation. Acute (1 h) treatment with 250 and 750 μM Ami reduced contractions by 50% and 84%, respectively, which was not associated with a directly proportional increase in whole tissue PKA activity. Sustained myometrial relaxation was observed during 24-h tissue culture with 750 μM Ami, which did not require P4 nor reduce CAPs. COX-2 protein can be reduced by 300 nM P4 but this did not equate to myometrial relaxation. Ami (250 μM) and P4 (100 and 300 nM) co-treatment did not prevent oxytocin-augmented contractions nor reduce CAPs during interleukin-1β stimulation. Overall, Ami and P4 co-treatment did not suppress myometrial contractions more than either agent alone, which may be attributed to low specificity and efficacy of Ami; cAMP and P4 action at in utero neighboring reproductive tissues during pregnancy should also be considered.

Transcription factors regulated by cAMP in smooth muscle of the myometrium at human parturition

Cyclic adenosine monophosphate (cAMP) contributes to maintenance of a quiescent (relaxed) state in the myometrium (i.e. uterine smooth muscle) during pregnancy, which most commonly has been attributed to activation of protein kinase A (PKA). PKA-mediated phosphorylation of cytosolic contractile apparatus components in myometrial smooth muscle cells (mSMCs) are known to promote relaxation. Additionally, PKA also regulates nuclear transcription factor (TF) activity to control expression of genes important to the labour process; these are mostly involved in actin-myosin interactions, cell-to-cell connectivity and inflammation, all of which influence mSMC transition from a quiescent to a contractile (pro-labour) phenotype. This review focuses on the evidence that cAMP modulates the activity of TFs linked to pro-labour gene expression, predominantly cAMP response element (CRE) binding TFs, nuclear factor κB (NF-κB), activator protein 1 (AP-1) family and progesterone receptors (PRs). This review also considers the more recently described exchange protein directly activated by cAMP (EPAC) that may oppose the pro-quiescent effects of PKA, as well as explores findings from other cell types that have the potential to be of novel relevance to cAMP action on TF function in the myometrium.

Molecular Evaluation of PROGINS Mutation in Progesterone Receptor Gene and Determination of its Frequency, Distribution Pattern and Association with Breast Cancer Susceptibility in Saudi Arabia

AIMS

Experimental and clinical evidence demonstrate that progesterone hormone and its nuclear receptor, the Progesterone Receptor (PR), play critical role in controlling mammary gland tumorigenesis and breast cancer development. Hormonal therapy (Tomaxifen) is the frontline treatment for hormone-dependent breast cancers. Progesterone hormone induces its action on the target cells by binding with its Progesterone receptor (PgR) therefore any genetic variations, which might induce alienation in the progesterone receptor, can result in an increased susceptibility of gynecological cancers. Alu insertion (PROGINS) mutation in PgR gene is reported to be associated with an increased risk of ovarian cancer and a decreased risk of breast cancer. However, its association with breast cancer risk remains inconclusive. Therefore, we investigated the association of PROGINS allele and its link with breast cancer risk.

METHODS

This case control study was performed on 200 subjects in which 100 were breast cancer cases and 100 gender matched healthy controls.The mutation was detected by using mutation specific PCR and results were confirmed by direct Sanger sequencing.

RESULTS

A clinically significant difference was reported in genotype distribution of PROGINs allele among the cases and gender-matched healthy controls (P<0. 032). Genotype frequencies of A1/A1, A1/A2, A2/A2 reported in cases was 81%, 19% (18% & 1%) and in matched healthy controls were 93%, 7% (6% & 1%). The higher frequency of PROGINs allele (19%) was observed in cases than the healthy controls (7%). The findings indicated that PgR variants (CC vs CT) increased the risk of Breast cancer in codominant inheritance model with OR= 3.44, 95% CI =1. 30-9.09, P<0.021) whereas nonsignificant association was found for CC vs TT genotypes with OR=1.14, 95% CI=0.07-18.658, P=0. 92. However, subgroup analysis revealed that CT + TT vs CC genotype increased the risk of breast cancer in dominant inheritance model tested OR = 3. 11, 95% CI = (1.24-7.79), P = 0.015). A nonsignificant association for PgR (CC+CT) vs TT) genotypes were reported in breast cancer OR = 1. 0, 95% CI= (0. 061-16.21), P=1) in recessive inheritance model tested. However, analysis with clinicalpathological variables revealed that the PROGINs allele is significantly associated with the distant metastasis and advanced stage of the disease.

CONCLUSION

The mutation specific PCR was successfully developed as an alternative to Sanger sequencing for the cost-effective detection for PROGINS allele of progesterone receptor gene. A clinically significant correlation of PROGINs allele was reported with the distant metastasis and advanced stage of the disease. Taken together, these results demonstrated that PROGINS variant is associated with an increased susceptibility to Breast cancer, providing novel insights into the genetic etiology and underlying biology of Breast carcinogenesis. Further studies with large sample sizes are required to validate our findings.