Gene expression and tyrosine kinase activity of insulin receptor in uterine leiomyoma and matched myometrium.

OBJECTIVE

Our objective was to determine the insulin receptor (IR) mRNA levels and IR tyrosine kinase activity in normal myometrium and leiomyoma.

DESIGN

Experimental study.

SETTING

Academic research center.

PATIENTS: Five women with leiomyoma submitted to hysterectomy.

INTERVENTION: Plasma membrane fraction of human myometrium and leiomyoma were prepared and samples were incubated with and without insulin. mRNA was isolated and RT-PCR with specific primers was performed.

MAIN OUTCOME MEASURE: Western blots of plasma membranes incubated with and without insulin were performed. Chemoluminescent methods followed by densitometry were used to assess IR autophosphorylation. RT-PCR with specific primers for IR gene sequences was used to determine IR mRNA levels.

RESULTS

IR mRNA levels in myometrium (0.634+/-0.038) and in leiomyoma (0.649+/-0.047; p=0.813) were not different. The degree of insulin-stimulated IR autophosphorylation (relative optical density of the 95 kDa band) was also not different between myometrium (1.496+/-0.310) and leiomyoma (1.593+/-0.129; p=0.650).

CONCLUSIONS

There was no difference in IR receptor expression and IR autophosphorylation between normal myometrium and leiomyoma. Other steps of insulin signaling chain may participate in the altered proliferation of leiomyomas.