evaluating-effectiveness-cancer-drug-sensitization-vitro

Evaluating the Effectiveness of Cancer Drug Sensitization <em>In Vitro</em> and <em>In Vivo</em>

Due to the high level of heterogeneity and mutations inherent in human cancers, single agent therapies, or combination regimens which target the same ...

Western University

The discovery of estrogen receptor-beta (ERbeta) in 1996 stimulated great interest in the physiological roles and molecular mechanisms of ERbeta action. We now know that ERbeta plays a major role in mediating estrogen action in several tissues and organ systems, including the ovary, cardiovascular system, brain, and the immune system, and that ERbeta and ERalpha generally play distinct physiological roles in the body. Although significant progress has been made toward understanding the molecular mechanisms of ERbeta action, particularly in vitro, there remains a large gap in our understanding of the mechanisms by which ERbeta elicits its biological functions in a true physiological context.

Minireview: Estrogen receptor-beta: mechanistic insights from recent studies.

Follicle-stimulating hormone (FSH)-mediated changes in granulosa cell adhesion and morphology are essential for preovulatory follicle development, given the dramatic changes in follicle size and granulosa cell number that occur during this transition. Members of the Eph-ephrin family of cell-positioning and adhesion molecules, a family that consists of ephrin ligands and their Ephrin (Eph) receptors, regulate cell location, adhesion, and migration during embryonic development and tumor growth. However, very little is known about ephrin signaling during folliculogenesis. We have found that FSH increases the expression of several members of the Eph-ephrin family and that this signaling regulates granulosa cell morphology and adhesion. FSH induced increased mRNA levels of the ephrin ligand, ephrin-A5 (Efna5), and its receptors, Eph receptors A3, A5, and A8 (Epha3, Epha5, and Epha8, respectively), in granulosa cells. Immunofluorescence studies indicated that EFNA5 and EPHA5 are located in the membrane of granulosa cells of developing mouse follicles. Eph-ephrin signaling directly affected granulosa cell morphology and adhesion. Recombinant EFNA5 reduced cell spreading and increased cell rounding in mouse primary granulosa cells and in a rat granulosa cell line, whereas EPHA5 reduced granulosa cell adhesion in both model systems. Both FSH and forskolin also increased Efna5 and Epha5 mRNA levels in rat and human granulosa cell lines, indicating that FSH regulates these genes via the cAMP-dependent protein kinase A pathway and that this regulation is conserved across different species. The present study identifies Eph-ephrin signaling as a novel FSH-mediated pathway regulating granulosa cell morphology and adhesion.

The ephrin signaling pathway regulates morphology and adhesion of mouse granulosa cells in vitro.

Tumor cells have unstable genomes relative to non-tumor cells. Decreased DNA integrity resulting from tumor cell instability is important in generating favorable therapeutic indices, and intact DNA repair mediates resistance to therapy. Targeting DNA repair to promote the action of anti-cancer agents is therefore an attractive therapeutic strategy. BRCA2 is involved in homologous recombination repair. BRCA2 defects increase cancer risk but, paradoxically, cancer patients with BRCA2 mutations have better survival rates. We queried TCGA data and found that BRCA2 alterations led to increased survival in patients with ovarian and endometrial cancer. We developed a BRCA2-targeting second-generation antisense oligonucleotide (ASO), which sensitized human lung, ovarian, and breast cancer cells to cisplatin by as much as 60%. BRCA2 ASO treatment overcame acquired cisplatin resistance in head and neck cancer cells, but induced minimal cisplatin sensitivity in non-tumor cells. BRCA2 ASO plus cisplatin reduced respiration as an early event preceding cell death, concurrent with increased glucose uptake without a difference in glycolysis. BRCA2 ASO and cisplatin decreased metastatic frequency in vivo by 77%. These results implicate BRCA2 as a regulator of metastatic frequency and cellular metabolic response following cisplatin treatment. BRCA2 ASO, in combination with cisplatin, is a potential therapeutic anti-cancer agent.

Article	Year
Minireview: Estrogen receptor-beta: mechanistic insights from recent studies. Molecular endocrinology (Baltimore, Md.)\| PubMed ID: 20363876	2010
The ephrin signaling pathway regulates morphology and adhesion of mouse granulosa cells in vitro. Biology of reproduction\| PubMed ID: 23242526	2013
BRCA2 inhibition enhances cisplatin-mediated alterations in tumor cell proliferation, metabolism, and metastasis. Molecular oncology\| PubMed ID: 24974076	2014

Adrian Buensuceso

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