Prolactin receptor antagonism uncouples lipids from atherosclerosis susceptibility

The role of prolactin/vasoinhibins in cardiovascular diseases

Prolactin (PRL) is a polypeptide hormone that is mainly synthesized and secreted by the lactotroph cells of the pituitary. There are two main isoforms of PRL: 23-kDa PRL (named full-length PRL) and vasoinhibins (including 5.6-18 kDa fragments). Both act as circulating hormones and cytokines to stimulate or inhibit vascular formation at different stages and neovascularization, including endothelial cell proliferation and migration, protease production, and apoptosis. However, their effects on vascular function and cardiovascular diseases are different or even contrary. In addition to the structure, secretion regulation, and signal transduction of PRL/vasoinhibins, this review focuses on the pathological mechanism and clinical significance of PRL/vasoinhibins in cardiovascular diseases.

Atorvastatin Upregulates the Expression of miR-126 in Apolipoprotein E-knockout Mice with Carotid Atherosclerotic Plaque

Carotid atherosclerosis (AS) is a chronic inflammatory disease of the carotid arterial wall, which is very important in terms of the occurrence of cerebral vascular accidents. Studies have demonstrated that microRNAs (miRNAs) and their target genes are involved in the formation of atherosclerosis and that atorvastatin might reduce atherosclerotic plaques by regulating the expression of miRNAs. However, the related mechanism is not yet known. In this study, we first investigated the effects of atorvastatin on miR-126 and its target gene, i.e., vascular cell adhesion molecule-1 (VCAM-1) in apolipoprotein E-knockout (ApoE-/-) mice with carotid atherosclerotic plaque in vivo. We compared the expressions of miR-126 and VCAM-1 between the control, atherosclerotic model and atorvastatin treatment groups of ApoE-/- mice using RT-PCR and Western blot. We found the miR-126 expression was significantly down-regulated, and the VCAM-1 expression was significantly up-regulated in the atherosclerotic model group, which accelerated the progression of atherosclerosis in the ApoE-/- mice. These results following atorvastatin treatment indicated that miR-126 expression was significantly up-regulated, VCAM-1 expression was significantly down-regulated and atherosclerotic lesions were reduced. The present results might explain the mechanism by which miR-126 is involved in the formation of atherosclerosis in vivo. Our study first indicated that atorvastatin might exert its anti-inflammatory effects in atherosclerosis by regulating the expressions of miR-126 and VCAM-1 in vivo.

The prolactin receptor as a therapeutic target in human diseases: browsing new potential indications

INTRODUCTION

Prolactin (PRL) signaling has emerged as a relevant target in breast and prostate cancers. This has encouraged various laboratories to develop compounds targeting the PRL receptor (PRLR). As the latter is widely distributed, it is timely to address whether other conditions could also benefit from such inhibitors.

AREAS COVERED

The authors briefly overview the two classes of PRLR blockers, which involve: i) PRL-core based analogs that have been validated as competitive antagonists in various preclinical models, and ii) anti-PRLR neutralizing antibodies that are currently in clinical Phase I for advanced breast and prostate cancers. The main purpose of this review is to discuss the multiple organs/diseases that may be considered as potential targets/indications for such inhibitors. This is done in light of reports suggesting that PRLR expression/signaling is increased in disease, and/or that systemic or locally elevated PRL levels correlate with (or promote) organ pathogenesis.

EXPERT OPINION

The two immediate challenges in the field are i) to provide the scientific community with potent anti-prolactin receptor antibodies to map prolactin receptor expression in target organs, and ii) to take advantage of the availability of functionally validated PRLR blockers to establish the relevance of these potential indications in humans.