Effects of insulin, insulin-like growth factor-I and -II on proliferation and intracellular signaling in endometrial carcinoma cells with different expression levels of insulin receptor isoform A.
- Author:
Chun-fang WANG
1
;
Guo ZHANG
;
Li-jun ZHAO
;
Xiao-ping LI
;
Wen-juan QI
;
Jian-liu WANG
;
Li-hui WEI
Author Information
- Publication Type:Journal Article
- MeSH: Antigens, CD; physiology; Apoptosis; drug effects; Cell Line, Tumor; Cell Proliferation; drug effects; Endometrial Neoplasms; metabolism; pathology; Female; Humans; Insulin; pharmacology; Insulin-Like Growth Factor I; pharmacology; Insulin-Like Growth Factor II; pharmacology; Intracellular Space; metabolism; Protein Isoforms; metabolism; Receptor, Insulin; physiology; Signal Transduction; drug effects
- From: Chinese Medical Journal 2013;126(8):1560-1566
- CountryChina
- Language:English
-
Abstract:
BACKGROUNDHyperinsulinemia, insulin-like growth factor (IGF)-I and -II (IGF-II) are associated with increased risk of endometrial carcinoma. Insulin receptor isoform A (IR-A) is more frequently expressed in endometrial carcinoma than in normal endometrial tissues. To better understand their roles in endometrial carcinoma, we investigated the effects of insulin, IGF-I, and IGF-II in endometrial carcinomas cells with different IR-A expression levels.
METHODSTo explore the role of IR-A in mediating the activity of IGF-I, IGF-II, and insulin, we investigate the cellular proliferation of endometrial carcinoma cell lines RL95-2 and RL95-2-IR-A by MTS assays. Then we examined the protein kinase Akt phosphorylation and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation in both cell lines by Western blotting. The effect of IGF-II and AG1024 on cell cycle progression and apoptosis was assessed by flowcytometry. To examine whether the effects of IGFs were mediated by IR-A, we blocked IGF-I receptor (IGF-IR) in both cell lines using AG1024, an IGF-IR-specific inhibitor.
RESULTSIGF-I and IGF-II significantly enhanced proliferation of both cell lines (P < 0.05). By contrast, insulin significantly increased proliferation of RL95-2-IR-A cells only (P < 0.05). IGF-I and IGF-II significantly increased pAkt levels in RL95-2 cells and pERK1/2 levels in RL95-2-IR-A cells (all, P < 0.05). Insulin increased pERK1/2 levels in RL95-2-IR-A cells only (P < 0.05). LY294002 and PD98059 inhibited the specific signaling activities and cellular proliferation. After AG1024 pretreatment, neither IGF-I nor IGF-II affected pAkt levels in RL95-2 cells. IGF-II, but not IGF-I, increased pERK1/2 levels in RL95-2-IR-A cells. After AG1024 pretreatment, the proliferation rate and DNA content corresponding to the S phase increased and apoptosis decreased significantly in IGF-II-treated RL95-2-IR-A cells only (P < 0.05).
CONCLUSIONSThe proliferation effect of insulin is mediated by IR-A. When IR-A dominates in a cell line, IGF-II activated cell proliferation mainly through the ERK1/2 pathway. On the other hand, IGF-II activated cell proliferation mainly through the Akt pathway. IR-A can at least partly mediate the proliferative and anti-apoptotic effects of IGF-II through the ERK1/2 pathway.
