Dysregulated chaperones associated with cell proliferation and negative apoptosis regulation in the uterine leiomyoma

Abstract

Uterine leiomyomas are benign smooth muscle cell tumors that originate from the myometrium. In this study we focus on dysregulated chaperones associated with cell proliferation and apoptosis. Paired tissue samples of 15 leiomyomas and adjacent myometria were obtained and analyzed by two-dimensional gel electrophoresis (2-DE). Mass spectrometry was used for protein identification and western blotting for 2-DE data validation. The values of 6 chaperones were found to be significantly different in the leiomyoma when compared with the myometrium. A total of 4 proteins were upregulated in the leiomyoma and 2 proteins were downregulated. Calreticulin and 78 kDa glucose-regulated protein were further validated by western blotting because the first is considered a marker of cell proliferation, while the second protects against apoptotic cell death. In addition, we also validated the two downregulated proteins heat shock protein β-1 and heat shock 70 kDa protein 1A. Our study shows the existence of a dysregulation of chaperone proteins associated with leiomyoma development. Functional studies are needed to ascertain the role of these chaperones in the leiomyoma. This may be crucial for the further development of specific inhibitors against the activity of these proteins in order to block the growth of the leiomyoma.

Keywords: leiomyoma; molecular chaperones; proteins; proteomics; two-dimensional electrophoresis.

Figure 1.

Two-dimensional electrophoresis map of normal myometrium and leiomyoma proteome. Immobilized pH gradient 3–10NL strips were used for the first dimension and 12% polyacrylamide gel was used for the second dimension. The numbered circles indicate the dysregulated chaperones.

Figure 2.

Western blot analysis of HSPA5 CALR, HSP1A1, HSPB1 in paired myometrium (M) and leiomyoma (L). The intensity of immunostained bands was normalized against the total protein intensities measured from the same blot stained with Coomassie Blue. Number 1–5 indicate the patients. The bar graph shows the relative expression (band density) of HSPA5, CALR, HSP1A1, HSPB1 in the myometrium and the leiomyoma. Results are shown as a histogram (P<0.05) and each bar represents mean ± standard deviation.

Figure 3.

Prediction by STRING database. (A) Chaperones interaction on confidence prediction. (B) Chaperones and key proteins present in (p38 MAPK pathway, VEGF signaling pathway, UPR pathway) on molecular action prediction. For A, line thickness indicates the strength of data support. For B, line shape indicates the predicted mode of action, and colors indicate action types: Green, activation; red, inhibition; blue, binding; purple, catalysis; light blue, phenotype; fuchsia, posttranslational modification; black, reaction; yellow, transcriptional regulation.