Gene Expression in Endocrine Tissues
(M481) MICROARRAY ANALYSIS OF OVARIAN GENE EXPRESSION IN FORKO MICE: INSIGHTS INTO THE MECHANISM OF FOLLITROPIN RECEPTOR SIGNALLING.
Aravindakshan, Jayaprakash1, Chen, Xin Lei1, Yang, Yinzhi1, Sairam, M Ram1, 1 Clinical Research Institute of Montréal, Montreal, Quebec, Canada
ABSTRACT- Follitropin Receptor Knockout (FORKO) mice present diverse abnormalities from infertility to increased ovarian tumor incidences, providing an anovulatory model valuable for studying ovarian biology and phenocopy of specific pathological states. To understand why FORKO mice develop these anomalies, we have used mRNA expression profiling to gain a more comprehensive view of genes that are misregulated. NIA 15K murine cDNA microarray studies and oligonucleotide array hybridization experiments using Affymetrix GeneChip identified hundreds of transcripts differentially expressed compared with wild type as early as 1 month. Gene transcripts for oncogenes and tumor markers such as CTGF, Tumor-associated calcium signal transducer 1, Lipocalin2 (oncogene 24p3), and claudin 3 were markedly elevated in FORKO ovaries. In parallel, down regulation of Deleted in Liver Cancer 1, Inhibin alpha and Septin -4 genes was observed, suggesting a potential increase for tumorigenesis. In contrast, increase in several genes like Serine Protease Inhibitor, Reversion-Inducing-Cysteine-Rich protein with Kazal motifs (RECK), Rho, GDP dissociation inhibitor (GDI) which are implicated in anti-metastatic properties, and are found to be upregulated may partially explain why ovarian tumors found in FORKO mice do not show metastatic tendencies. We selected 25 genes implicated in ovarian growth and tumors in general for further characterization by Q-PCR. Additionally, we also performed immunohistochemistry and western blot to localize CTGF, TIMP-2, IGF-1, Claudin-3 and lactoferrin and to verify if changes in mRNA are reflected at the protein level. In FORKO mice follicular growth is impaired before the preantral stage and there is a hypertrophy of theca cells. Expression of several of these proteins along with quantitation and their postulated functions suggest that they mediate critical processes in normal physiology and events leading up to pathology of ovarian tissue. Thus the ovary in a state where ovulation is suppressed still retains its propensity to become tumorigenic suggesting FSH-R signalling has a beneficial effect in suppressing this (Supported by NCIC and CIHR).
KEY WORDS: ovary, microarray, follitropin receptor knockout