Current trends in drug metabolism and pharmacokinetics.

Pharmacokinetics (PK) is the study of the absorption, distribution, metabolism, and excretion (ADME) processes of a drug. Understanding PK properties is essential for drug development and precision medication. In this review we provided an overview of recent research on PK with focus on the following aspects: (1) an update on drug-metabolizing enzymes and transporters in the determination of PK, as well as advances in xenobiotic receptors and noncoding RNAs (ncRNAs) in the modulation of PK, providing new understanding of the transcriptional and posttranscriptional regulatory mechanisms that result in inter-individual variations in pharmacotherapy; (2) current status and trends in assessing drug-drug interactions, especially interactions between drugs and herbs, between drugs and therapeutic biologics, and microbiota-mediated interactions; (3) advances in understanding the effects of diseases on PK, particularly changes in metabolizing enzymes and transporters with disease progression; (4) trends in mathematical modeling including physiologically-based PK modeling and novel animal models such as CRISPR/Cas9-based animal models for DMPK studies; (5) emerging non-classical xenobiotic metabolic pathways and the involvement of novel metabolic enzymes, especially non-P450s. Existing challenges and perspectives on future directions are discussed, and may stimulate the development of new research models, technologies, and strategies towards the development of better drugs and improved clinical practice

The Orphan Nuclear Receptor LRH-1 and ERα Activate GREB1 Expression to Induce Breast Cancer Cell Proliferation

BACKGROUND: Liver Receptor Homolog 1 (LRH-1, NR5A2) is an orphan nuclear receptor that is over-expressed in cancers in tissues such as the breast, colon and pancreas. LRH-1 plays important roles in embryonic development, steroidogenesis and cholesterol homeostasis. In tumor cells, LRH-1 induces proliferation and cell cycle progression. High LRH-1 expression is demonstrated in breast cancers, positively correlating with ERα status and aromatase activity. LRH-1 dependent cellular mechanisms in breast cancer epithelial cells are poorly defined. Hence in the present study we investigated the actions of LRH-1 in estrogen receptor α (ERα) positive breast cancer cells. RESULTS: The study aimed to investigate LRH-1 dependent mechanisms that promote breast cancer proliferation. We identified that LRH-1 regulated the expression of Growth Regulation by Estrogen in Breast Cancer 1 (GREB1) in MCF-7 and MDA-MB-231 cells. Over-expression of LRH-1 increased GREB1 mRNA levels while knockdown of LRH-1 reduced its expression. GREB1 is a well characterised ERα target gene, with three estrogen response elements (ERE) located on its promoter. Chromatin immunoprecipitation studies provided evidence of the co-localisation of LRH-1 and ERα at all three EREs. With electrophoretic mobility shift assays, we demonstrated direct binding of LRH-1 to EREs located on GREB1 and Trefoil Factor 1 (TFF1, pS2) promoters. LRH-1 and ERα co-operatively activated transcription of ERE luciferase reporter constructs suggesting an overlap in regulation of target genes in breast cancer cells. Over-expression of LRH-1 resulted in an increase in cell proliferation. This effect was more pronounced with estradiol treatment. In the presence of ICI 182,780, an ERα antagonist, LRH-1 still induced proliferation. CONCLUSIONS: We conclude that in ER-positive breast cancer cells, LRH-1 promotes cell proliferation by enhancing ERα mediated transcription of target genes such as GREB-1. Collectively these findings indicate the importance of LRH-1 in the progression of hormone-dependent breast cancer and implicate LRH-1 as a potential avenue for drug development

Identification of androgen receptor splice variant transcripts in breast cancer cell lines and human tissues

The androgen receptor (AR) is widely expressed in human tissues and has biological function in many male and female organs. In particular, the AR plays a critical role in the biology and pathology of the prostate gland. AR activity inhibits breast growth and has pleiotropic actions in breast cancer that are subtype-dependent. Expression of AR splice variants (ARVs) and their role in prostate carcinogenesis has been elucidated in recent studies. We hypothesised that ARVs are also expressed in breast cancers and other hormone sensitive tissues. Herein, the expression of five previously identified ARV transcripts with documented transcriptional capacity (AR-V1, -V3, -V4, -V7, and -V9) was examined in 6 breast (MFM223, MDA-MB-453, MDA-MB-231, ZR75.1, MCF-7, T47D), two prostate (VCaP, LNCaP), and one liver (HepG2) cancer cell lines, a human embryonic kidney cell line (HEK293), and a panel of RNAs representing 21 different human tissues. Four ARVs (V1, V3, V7, V9) were detected to some degree in almost all cell lines and tissues. In addition, four novel ARVs containing a cryptic exon 9 (CE9) were detected in MDA-MB-453 and VCaP cells. Sequencing of ARV amplicons revealed a single nucleotide substitution within CE3 in lung and placental tissue samples that could be translated as an Ile (ATT)>Val (GTT) substitution in the AR-V7 variant protein. Collectively, these data provides insight into the potential complexity of AR transcriptional splicing events in breast cancer cell lines and diverse human tissues, thereby establishing a rationale for further exploration of ARVs in breast cancer and other human pathologies.Dong Gui Hu, Theresa E. Hickey, Connie Irvine, Dhilushi Dodampege Wijayakumara, Lu Lu, Wayne D. Tilley, Luke A. Selth, Peter I. Mackenzi

LRH-1 acts synergistically with ERα to activate ERE containing promoters.

<p>Transcriptional activation of (a) 2×ERE and (b) GREB-ERE2 luciferase reporters by ERα and LRH-1 with vehicle (veh) or 10 nM 17β-estradiol (E2). Estrogen-deprived MCF-7 cells were over expressed with LRH-1 or ERα alone, or in combination with the appropriate reporter construct. Cells were treated with 17β-estradiol for 16 h prior to luciferase assays. Data is presented as mean+SE, n = 3 separate experiments, treatments in triplicate per experiment. *P&lt;0.05, *P&lt;0.01, ***P&lt;0.001 compared to vehicle control unless indicated by reference line.</p

Synergistic effects of LRH-1 and 17β-estradiol treatment on GREB1 expression.

<p>Quantitation of (a) LRH-1, (b) GREB1 and (c) ERα mRNA expression in estrogen-deprived MCF-7 cells (control) or LRH-1 over-expressing (+LRH-1) MCF-7 cells treated with vehicle (veh) or 10 nM 17β-estradiol (E2) for 16 h. Data is presented as mean+SE, n = 3 separate experiments, triplicate treatments per experiment, **P&lt;0.01, ***P&lt;0.001 compared to vehicle control.</p