Prolactin receptor gene transcriptional control, regulatory modalities relevant to breast cancer resistance and invasiveness

IκBα kinase inhibitor BAY 11-7082 promotes anti-tumor effect in RAS-driven cancers

BACKGROUND

Oncogenic mutations in the RAS gene are associated with uncontrolled cell growth, a hallmark feature contributing to tumorigenesis. While diverse therapeutic strategies have been diligently applied to treat RAS-mutant cancers, successful targeting of the RAS gene remains a persistent challenge in the field of cancer therapy. In our study, we discover a promising avenue for addressing this challenge.

METHODS

In this study, we tested the viability of several cell lines carrying oncogenic NRAS, KRAS, and HRAS mutations upon treatment with IkappaBalpha (IκBα) inhibitor BAY 11-7082. We performed both cell culture-based viability assay and in vivo subcutaneous xenograft-based assay to confirm the growth inhibitory effect of BAY 11-7082. We also performed large RNA sequencing analysis to identify differentially regulated genes and pathways in the context of oncogenic NRAS, KRAS, and HRAS mutations upon treatment with BAY 11-7082.

RESULTS

We demonstrate that oncogenic NRAS, KRAS, and HRAS activate the expression of IκBα kinase. BAY 11-7082, an inhibitor of IκBα kinase, attenuates the growth of NRAS, KRAS, and HRAS mutant cancer cells in cell culture and in mouse model. Mechanistically, BAY 11-7082 inhibitor treatment leads to suppression of the PI3K-AKT signaling pathway and activation of apoptosis in all RAS mutant cell lines. Additionally, we find that BAY 11-7082 treatment results in the downregulation of different biological pathways depending upon the type of RAS protein that may also contribute to tumor growth inhibition.

CONCLUSION

Our study identifies BAY 11-7082 to be an efficacious inhibitor for treating RAS oncogene (HRAS, KRAS, and NRAS) mutant cancer cells. This finding provides new therapeutic opportunity for effective treatment of RAS-mutant cancers.

Current Insights in Prolactin Signaling and Ovulatory Function

Prolactin (PRL) is a pleiotropic hormone released from lactotrophic cells of the anterior pituitary gland that also originates from extrapituitary sources and plays an important role in regulating lactation in mammals, as well as other actions. Acting in an endocrine and paracrine/autocrine manner, PRL regulates the hypothalamic-pituitary-ovarian axis, thus influencing the maturation of ovarian follicles and ovulation. This review provides a detailed discussion of the current knowledge on the role of PRL in the context of ovulation and ovulatory disorders, particularly with regard to hyperprolactinemia, which is one of the most common causes of infertility in women. Much attention has been given to the PRL structure and the PRL receptor (PRLR), as well as the diverse functions of PRLR signaling under normal and pathological conditions. The hormonal regulation of the menstrual cycle in connection with folliculogenesis and ovulation, as well as the current classifications of ovulation disorders, are also described. Finally, the state of knowledge regarding the importance of TIDA (tuberoinfundibular dopamine), KNDγ (kisspeptin/neurokinin B/dynorphin), and GnRH (gonadotropin-releasing hormone) neurons in PRL- and kisspeptin (KP)-dependent regulation of the hypothalamic-pituitary-gonadal (HPG) axis in women is reviewed. Based on this review, a rationale for influencing PRL signaling pathways in therapeutic activities accompanying ovulation disorders is presented.

High-dimensional phenotyping to define the genetic basis of cellular morphology

The morphology of cells is dynamic and mediated by genetic and environmental factors. Characterizing how genetic variation impacts cell morphology can provide an important link between disease association and cellular function. Here, we combine genomic sequencing and high-content imaging approaches on iPSCs from 297 unique donors to investigate the relationship between genetic variants and cellular morphology to map what we term cell morphological quantitative trait loci (cmQTLs). We identify novel associations between rare protein altering variants in WASF2, TSPAN15, and PRLR with several morphological traits related to cell shape, nucleic granularity, and mitochondrial distribution. Knockdown of these genes by CRISPRi confirms their role in cell morphology. Analysis of common variants yields one significant association and nominate over 300 variants with suggestive evidence (P < 10-6) of association with one or more morphology traits. We then use these data to make predictions about sample size requirements for increasing discovery in cellular genetic studies. We conclude that, similar to molecular phenotypes, morphological profiling can yield insight about the function of genes and variants.

The conceivable role of prolactin hormone in Parkinson disease: The same goal but with different ways

Parkinson disease (PD) is a progressive neurodegenerative disease (NDD) of the brain. It has been reported that prolactin (PRL) hormone plays a differential effect in PD, may be increasing, reduced or unaffected. PRL level is dysregulated in different neurodegenerative disorders including PD. Preclinical and clinical studies pointed out that PRL may has a neuroprotective against PD neuropathology . Though, the mechanistic role of PRL in PD is not fully elucidated. Therefore, the objective of the present review was to clarify the potential role and mechanistic pathway of PRL in PD neuropathology. The present review highlighted that PRL appears to have a neuroprotective effect against PD neuropathology by inhibiting the expression of pro-inflammatory signaling pathways, antioxidant effects and by inhibiting neuroinflammation. Thus, preclinical and clinical studies are warranted in this regard.

Advancements in clinical aspects of targeted therapy and immunotherapy in breast cancer

Breast cancer is the second leading cause of death for women worldwide. The heterogeneity of this disease presents a big challenge in its therapeutic management. However, recent advances in molecular biology and immunology enable to develop highly targeted therapies for many forms of breast cancer. The primary objective of targeted therapy is to inhibit a specific target/molecule that supports tumor progression. Ak strain transforming, cyclin-dependent kinases, poly (ADP-ribose) polymerase, and different growth factors have emerged as potential therapeutic targets for specific breast cancer subtypes. Many targeted drugs are currently undergoing clinical trials, and some have already received the FDA approval as monotherapy or in combination with other drugs for the treatment of different forms of breast cancer. However, the targeted drugs have yet to achieve therapeutic promise against triple-negative breast cancer (TNBC). In this aspect, immune therapy has come up as a promising therapeutic approach specifically for TNBC patients. Different immunotherapeutic modalities including immune-checkpoint blockade, vaccination, and adoptive cell transfer have been extensively studied in the clinical setting of breast cancer, especially in TNBC patients. The FDA has already approved some immune-checkpoint blockers in combination with chemotherapeutic drugs to treat TNBC and several trials are ongoing. This review provides an overview of clinical developments and recent advancements in targeted therapies and immunotherapies for breast cancer treatment. The successes, challenges, and prospects were critically discussed to portray their profound prospects.

PRL-R Variants Are Not Only Associated With Prolactinomas But Also With Dopamine Agonist Resistance

CONTEXT

Knockout prolactin receptor gene (PRL-R) mice are animal models for prolactinomas and PRL acts via autocrine/paracrine inhibiting lactotroph proliferation. Recently, variants of the PRL-R were identified in prolactinoma patients and their frequency was higher compared to individuals from the genomic database.

OBJECTIVE

We analyzed PRL-R variants frequency in an extensive cohort of prolactinoma patients and evaluated their association with clinical, laboratorial, and imaging characteristics and hormonal response to cabergoline.

DESIGN

Observational, retrospective, and cross-sectional study.

SETTING

This study took place at the Neuroendocrinology Unit of Clinics Hospital, Medical School of University of São Paulo, Brazil, a tertiary referral center.

PATIENTS AND METHODS

Study participants included adults with sporadic prolactinomas treated with cabergoline, where response to therapy was defined by prolactin normalization with up to 3 mg/week doses. DNA was extracted from blood samples and the PRL-R was analyzed by polymerase chain reaction techniques and automatic sequencing. The association of PRL-R variants with serum prolactin levels, maximal tumor diameter, tumor parasellar invasiveness, and response to cabergoline was analyzed.

RESULTS

We found 6 PRL-R variants: p.Ile100(76)Val, p.Ile170(146)Leu, p.Glu400(376)Gln/p.Asn516(492)Ile, p.Glu470Asp e p.Ala591Pro; the last 2 are newly described in prolactinomas' patients. The variants p.Glu400(376)Gln/p.Asn516(492)Ile and p.Ala591Pro were more frequent amongst patients compared to genomic databases, and the p.Asn516(492)Ile showed pathogenic potential using in silico analysis as previously described. PRL-R variants were associated with male sex (P = 0.015), higher serum PRL levels (P = 0.007), larger tumors (P = 0.001), and cabergoline resistance (P < 0.001).

CONCLUSIONS

The prolactin/prolactin receptor system seems to be related to prolactinoma tumorigenesis and cabergoline resistance. Additional studies are needed to better understand the PRL-R variants' role and their potential as therapeutic targets.

Immunomodulatory role of decidual prolactin on the human fetal membranes and placenta

The close interaction between fetal and maternal cells during pregnancy requires multiple immune-endocrine mechanisms to provide the fetus with a tolerogenic environment and protection against any infectious challenge. The fetal membranes and placenta create a hyperprolactinemic milieu in which prolactin (PRL) synthesized by the maternal decidua is transported through the amnion-chorion and accumulated into the amniotic cavity, where the fetus is bedded in high concentrations during pregnancy. PRL is a pleiotropic immune-neuroendocrine hormone with multiple immunomodulatory functions mainly related to reproduction. However, the biological role of PRL at the maternal-fetal interface has yet to be fully elucidated. In this review, we have summarized the current information on the multiple effects of PRL, focusing on its immunological effects and biological significance for the immune privilege of the maternal-fetal interface.

Isoform-specific knockdown of long and intermediate prolactin receptors interferes with evolution of B-cell neoplasms

Prolactin (PRL) is elevated in B-cell-mediated lymphoproliferative diseases and promotes B-cell survival. Whether PRL or PRL receptors drive the evolution of B-cell malignancies is unknown. We measure changes in B cells after knocking down the pro-proliferative, anti-apoptotic long isoform of the PRL receptor (LFPRLR) in vivo in systemic lupus erythematosus (SLE)- and B-cell lymphoma-prone mouse models, and the long plus intermediate isoforms (LF/IFPRLR) in human B-cell malignancies. To knockdown LF/IFPRLRs without suppressing expression of the counteractive short PRLR isoforms (SFPRLRs), we employ splice-modulating DNA oligomers. In SLE-prone mice, LFPRLR knockdown reduces numbers and proliferation of pathogenic B-cell subsets and lowers the risk of B-cell transformation by downregulating expression of activation-induced cytidine deaminase. LFPRLR knockdown in lymphoma-prone mice reduces B-cell numbers and their expression of BCL2 and TCL1. In overt human B-cell malignancies, LF/IFPRLR knockdown reduces B-cell viability and their MYC and BCL2 expression. Unlike normal B cells, human B-cell malignancies secrete autocrine PRL and often express no SFPRLRs. Neutralization of secreted PRL reduces the viability of B-cell malignancies. Knockdown of LF/IFPRLR reduces the growth of human B-cell malignancies in vitro and in vivo. Thus, LF/IFPRLR knockdown is a highly specific approach to block the evolution of B-cell neoplasms.

Prolactin receptor signaling: A novel target for cancer treatment - Exploring anti-PRLR signaling strategies

Prolactin (PRL) is a peptide hormone mainly secreted from the anterior pituitary gland. PRL is reported to play a role in pregnancy, mammary gland development, immune modulation, reproduction, and differentiation of islet cells. PRL binds to its receptor PRLR, which belongs to a superfamily of the class I cytokine receptor that has no intrinsic kinase activity. In canonical signaling, PRL binding to PRLR induces downstream signaling including JAK-STAT, AKT and MAPK pathways. This leads to increased cell proliferation, stemness, migration, apoptosis inhibition, and resistance to chemotherapy. PRL-signaling is upregulated in numerous hormone-dependent cancers including breast, prostate, ovarian, and endometrial cancer. However, more recently, the pathway has been reported to play a tumor-promoting role in other cancer types such as colon, pancreas, and hepatocellular cancers. Hence, the signaling pathway is an attractive target for drug development with blockade of the receptor being a potential therapeutic approach. Different strategies have been developed to target this receptor including modification of PRL peptides (Del1-9-G129R-hPRL, G129R-Prl), growth hormone receptor/prolactin receptor bispecific antibody antagonist, neutralizing antibody LFA102, an antibody-drug conjugate (ABBV-176) of the humanized antibody h16f (PR-1594804) and pyrrolobenzodiazepine dimer, a bispecific antibody targeting both PRLR and CD3, an in vivo half-life extended fusion protein containing PRLR antagonist PrlRA and albumin binding domain. There have also been attempts to discover and develop small molecular inhibitors targeting PRLR. Recently, using structure-based virtual screening, we identified a few antipsychotic drugs including penfluridol as a molecule that inhibits PRL-signaling to inhibit PDAC tumor progression. In this review, we will summarize the recent advances in the biology of this receptor in cancer and give an account of PRLR antagonist development for the treatment of cancer.