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Clin Cancer Res. 2009 Sep 1;15(17):5445-56. doi: 10.1158/1078-0432.CCR-08-2980. Epub 2009 Aug 25.

Insulin-like growth factor-1 receptor inhibition induces a resistance mechanism via the epidermal growth factor receptor/HER3/AKT signaling pathway: rational basis for cotargeting insulin-like growth factor-1 receptor and epidermal growth factor receptor in hepatocellular carcinoma.

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1
UPMC Univ Paris 06, Paris, France. christele.desbois-mouthon@inserm.fr

Abstract

PURPOSE:

The insulin-like growth factor (IGF) signaling axis is frequently dysregulated in hepatocellular carcinoma (HCC). Therefore, we investigated whether the specific targeting of the IGF type 1 receptor (IGF-1R) might represent a new therapeutic approach for this tumor.

EXPERIMENTAL DESIGN:

Total and phosphorylated levels of IGF-1R were measured in 21 paired samples of human HCCs and adjacent nontumoral livers using ELISA. The antineoplastic potency of a novel anti-IGF-1R antibody, AVE1642, was examined in five human hepatoma cell lines.

RESULTS:

Overexpression of IGF-1R was detected in 33% of HCCs and increased activation of IGF-1R was observed in 52% of tumors. AVE1642 alone had moderate inhibitory effects on cell viability. However, its combination with gefitinib, an epidermal growth factor receptor (EGFR) inhibitor, induced supra-additive effects in all cell lines that were associated with cell cycle blockage and inhibition of AKT phosphorylation. The combination of AVE1642 with rapamycin also induced a synergistic reduction of viability and of AKT phosphorylation. Of marked interest, AVE1642 alone up-regulated the phosphorylated and total levels of HER3, the main partner of EGFR, and AVE1642-induced phosphorylation of HER3 was prevented by gefitinib. Moreover, the down-regulation of HER3 expression with siRNA reduced AKT phosphorylation and increased cell sensitivity to AVE1642.

CONCLUSIONS:

These findings indicate that hepatoma cells overcome IGF-1R inhibition through HER3 activation in an EGFR-dependent mechanism, and that HER3 represents a critical mediator in acquired resistance to anti-IGF-1R therapy. These results provide a strong rational for targeting simultaneously EGFR and IGF-1R in clinical trials for HCC].

PMID:
19706799
DOI:
10.1158/1078-0432.CCR-08-2980
[Indexed for MEDLINE]
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