Molecular profiling of experimental endometriosis identified gene expression patterns in common with human disease

Abstract

Objective: To validate a rat model of endometriosis using complimentary DNA (cDNA) microarrays by identifying common gene expression patterns between experimental and natural disease.

Design: Autotransplantation rat model.

Setting: Medical school department.

Animals: Female Sprague-Dawley rats.

Intervention(s): Endometriosis was surgically induced by suturing uterine horn implants next to the small intestine's mesentery. Control rats received sutures with no implants. After 60 days, endometriotic implants and uterine horn were obtained.

Main outcome measure(s): Gene expression levels determined by cDNA microarrays and real-time quantitative polymerase chain reaction (qPCR). The Cy5-labeled cDNA was synthesized from total RNA obtained from endometriotic implants. The Cy3-labeled cDNA was synthesized using uterine RNA from a control rat. Gene expression levels were analyzed after hybridizing experimental and control labeled cDNA to PIQOR (Parallel Identification and Quantification of RNAs) Toxicology Rat Microarrays (Miltenyi Biotec, Cologne, Germany) containing 1,252 known genes. The Cy5/Cy3 ratios were determined, and genes with >2-fold higher or <0.5-fold lower expression levels were selected. Microarray results were validated by QRT-PCR.

Result(s): We observed differential expression of genes previously shown to be up-regulated in patients, including growth factors, inflammatory cytokines/receptors, tumor invasion/metastasis factors, adhesion molecules, and antiapoptotic factors.

Conclusion(s): This study presents evidence in support of using this rat model to study the natural history of endometriosis and to test novel therapeutics for this incurable disease.

Figure 1

Scatter plots of gene expression levels in experimental (n=6) and control (n=5) rats analyzed by RT-PCR. Unpaired t-tests were conducted to determine significant differences in the mean level of gene expression between the groups. Significance was set at p<0.05; * indicates a p value <0.05, ** a p value <0.01.

Figure 2

Comparison of fold-expression of candidate genes in ectopic versus eutopic endometrium analyzed by either microarrays or real-time QRT-PCR.

Figure 3

A model of disease for endometriosis based on data from both animal and human studies