Differential expression of Akt/protein kinase B, Bcl-2 and Bax proteins in human leiomyoma and myometrium

Kovács, Kálmán; Lengyel, Ferenc; Környei, J.; Vértes, Zsuzsanna; Szabó, István; Sümegi, Balázs; Vértes, Marietta

doi:10.1016/j.jsbmb.2003.09.007

Cited by 52 publications

(54 citation statements)

References 41 publications

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“…This is consistent with our previous findings that a higher rate of cell proliferation appears to play the predominant role in uterine leiomyoma growth, and that neither prolonged cell survival, nor loss of expression of apoptosis-inducing proteins, or increased apoptosis, were likely to be significant mechanisms of uterine leiomyoma cell growth (18). However, another group found higher expression of phospho-AKT in leiomyomas than in myometrial tissue (43,44), which may be due to differences in sampling and/or assays used to determine phosphorylated AKT or total AKT levels. We used immunohistochemistry, western blot analysis, and in vitro studies to evaluate the expression levels of total and phosphorylated AKT in leiomyoma and myometrial tissue and in leiomyoma cells.…”

Section: Discussionsupporting

confidence: 92%

Differential Expression of Receptor Tyrosine Kinases (RTKs) and IGF-I Pathway Activation in Human Uterine Leiomyomas

Saile

Swartz

et al. 2008

Mol Med

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Uterine leiomyomas (fibroids) are benign tumors that are prevalent in women of reproductive age. Research suggests that activated receptor tyrosine kinases (RTKs) play an important role in the enhanced proliferation observed in fibroids. In this study, a phospho-RTK array technique was used to detect RTK activity in leiomyomas compared with myometrial tissue. We found that fifteen out of seventeen RTKs evaluated in this study were highly expressed (P < 0.02-0.03) in the leiomyomas, and included the IGF-I/IGF-IR, EGF/EGFR, FGF/FGF-R, HGF/HGF-R, and PDGF/PDGF-R gene families. Due to the higher protein levels of IGF-IR observed in leiomyomas by us in earlier studies, we decided to focus on the activation of the IGF-IR, its downstream effectors, and MAPKp44/42 to confirm our earlier findings; and validate the significance of the increased IGF-IR phosphorylation observed by RTK array analysis in this study. We used immunolocalization, western blot, or immunoprecipitation studies and confirmed that leiomyomas overexpressed IGF-IRβ and phosphorylated IGF-IRβ. Additionally, we showed that the downstream effectors, Shc, Grb2, and MAPKp44/42 (P < 0.02-0.001) were also overexpressed and involved in IGF-IR signaling in these tumors, while IRS-I, PI3K, and AKT were not. In vitro studies showed that IGF-I (100 ng/mL) increased the proliferation of uterine leiomyoma cells (UtLM) (P < 0.0001), and that phosphorylated IGF-IRβ, Shc, and MAPKp44/42 were also overexpressed in IGF-I-treated UtLM cells (P < 0.05), similar to the tissue findings. A neutralizing antibody against the IGF-IRβ blocked these effects. These data indicate that overexpression of RTKs and, in particular, activation of the IGF-IR signaling pathway through Shc/Grb2/MAPK are important in mediating uterine leiomyoma growth. These data may provide new anti-tumor targets for noninvasive treatment of fibroids.

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Section: Discussionsupporting

confidence: 92%

Differential Expression of Receptor Tyrosine Kinases (RTKs) and IGF-I Pathway Activation in Human Uterine Leiomyomas

Saile

Swartz

et al. 2008

Mol Med

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“…We found an upregulation of insulin-like growth factor 1, insulin-like growth factor receptor, AKT kinase and phosphatidylinositol 3-kinase in 20-40% of cases leiomyomata (Figure 3). Our results as well as published data 29,30,37 provide an evidence of increased activity of the insulin pathway in leiomyomata. However, there is a weak association between alteration of tuberin and the activity of the insulin-signaling pathway (Figures 3a and 4a).…”

Section: Discussionsupporting

confidence: 89%

“…28,29 It has been shown that AKT and phosphatidylinositol 3-kinase were upregulated in fibroid. 30 Our data showed a similar finding but statistically insignificant due to a large variation ( Figure 2, Table 2). In general, the upregulation of these markers was presented in only a portion of leiomyomata ranging from 20 to 40% of leiomyomata (9-22 cases out of 52-55 cases).…”

Section: Immunohistochemical Data In the Panelssupporting

confidence: 79%

Expression profile of tuberin and some potential tumorigenic factors in 60 patients with uterine leiomyomata

et al. 2005

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Human uterine leiomyomata are the most common tumors in women of reproductive age. The pathogenesis of leiomyomata remains unknown. An animal model of Eker rats with deleted tuberous sclerosis complex gene 2 (tuberin) shows increased incidence of leiomyomata. The role of tuberin in human leiomyomata is unknown. In this study, we designed a tissue microarray with tissue cores of leiomyomata and the matched myometrium from 60 hysterectomy specimens. We examined the expression of tuberin and tuberous sclerosis complex gene 1 product hamartin, proteins of the insulin-signaling pathway, steroid receptors and some of their cofactors, and human mobility group gene A2 by immunohistochemistry. We found that nearly half of the cases displayed either reduction or loss of tuberin in leiomyomata compared with matched normal myometrium. No change of hamartin was noted. Furthermore, a significant reduction of glucocorticoid receptor was found in leiomyomata with reduced tuberin. The proteins insulin like growth factor 1, insulin-like growth factor receptor b, AKT kinase, and phosphatidylinositol 3-kinase were upregulated. Nearly half of leiomyomata show upregulation of human mobility group gene A2, along with the steroid receptor cofactors. Our findings suggest that there are two broad groups of uterine leiomyomata. One group is associated with an alteration of tuberin and glucocorticoid receptor. The other group is associated with upregulation of human mobility group gene A2 and steroid receptor cofactors.

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“…Bcl-2 protein was reported to be over-expressed in leiomyomas when compared with homologous myometrium. Expression of Bcl-2 protein showed a strong correlation to ERs in leiomyoma [3,4] . Estrogen inhibits apoptosis in several cell types by inducing Bcl-2 expression [5,6] , and an anti-estrogen reagent induced apoptosis by down-regulating the expression of Bcl-2 protein [7] .…”

Section: Introductionmentioning

confidence: 90%

Involvement of Bcl-2, Src, and ERα in gossypol-mediated growth inhibition and apoptosis in human uterine leiomyoma and myometrial cells

et al. 2010

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Aim:To investigate the effect of gossypol on the growth of cultured human uterine leiomyoma and myometrial cells, the level of Bcl-2 and the activity of Src and estrogen receptor (ERα). Methods: Human uterine leiomyoma and adjacent normal myometrial cells were cultured in vitro. Both cell types were treated with a graded concentration of gossypol. Cell viability was assayed using CCK-8. Morphological change was observed with optical and electronic microscopy. Apoptosis was evaluated using TUNEL assay. Levels of Bcl-2, ERα and Src were analyzed using Western blotting. Results: Gossypol significantly inhibited growth and promoted apoptosis in cultured human uterine leiomyoma cells with the IC 50 value and its corresponding 95% confidence intervals (CI) of 6.5 (4.0-10.5), 9.0 (4.9-16.5), and 7.5 (4.0-14.1) μmol/L at 20, 40, and 60 h, respectively. Gossypol exerted inhibitory effects on the myometrial cells with the IC 50 value and its 95% CI of 49.1 (28.3-85.0), 14.5 (7.7-27.4), and 2.6 (1.2-5.6) μmol/L at 20, 40, and 60 h, respectively. Compared with control, gossypol 0.1-3.0 μmol/L markedly decreased the protein expression of Bcl-2 (P<0.05) in both leiomyoma and myometrial cells in a concentration-dependent manner, and significantly suppressed the level of phospho-Tyr416Src (P<0.05) in both cell types at 3.0 µmol/L without obvious alteration of c-Src and phospho-Tyr527Src levels (P>0.05). In addition, gossypol markedly reduced both the expression of ERα (P<0.05) at the low concentration of 0.1 µmol/L in the myometrial cells and the level of phospho-ser167ERα (P<0.05) at the high concentration of 3.0 µmol/L in the leiomyoma cells. Conclusion: Gossypol inhibits proliferation and induces apoptosis in human uterine leiomyoma and myometrial cells. It is likely that the mechanisms of action involve reducing the protein level of Bcl-2 and the activity of Src and ERα.

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Differential expression of Akt/protein kinase B, Bcl-2 and Bax proteins in human leiomyoma and myometrium

Cited by 52 publications

References 41 publications

Differential Expression of Receptor Tyrosine Kinases (RTKs) and IGF-I Pathway Activation in Human Uterine Leiomyomas

Differential Expression of Receptor Tyrosine Kinases (RTKs) and IGF-I Pathway Activation in Human Uterine Leiomyomas

Expression profile of tuberin and some potential tumorigenic factors in 60 patients with uterine leiomyomata

Involvement of Bcl-2, Src, and ERα in gossypol-mediated growth inhibition and apoptosis in human uterine leiomyoma and myometrial cells

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