Short-hairpin RNA-induced suppression of adenine nucleotide translocase-2 in breast cancer cells restores their susceptibility to TRAIL-induced apoptosis by activating JNK and modulating TRAIL receptor expression.

Abstract

BACKGROUND:

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL; apo2 ligand) induces apoptosis in cancer cells but has little effect on normal cells. However, many cancer cell types are resistant to TRAIL-induced apoptosis, limiting the clinical utility of TRAIL as an anti-cancer agent. We previously reported that the suppression of adenine nucleotide translocase-2 (ANT2) by short-hairpin RNA (shRNA) induces apoptosis of breast cancer cells, which frequently express high levels of ANT2. In the present study, we examined the effect of RNA shRNA-induced suppression of ANT2 on the resistance of breast cancer cells to TRAIL-induced apoptosis in vitro and in vivo.

RESULTS:

ANT2 shRNA treatment sensitized MCF7, T47 D, and BT474 cells to TRAIL-induced apoptosis by up-regulating the expression of TRAIL death receptors 4 and 5 (DR4 and DR5) and down-regulating the TRAIL decoy receptor 2 (DcR2). In MCF7 cells, ANT2 knockdown activated the stress kinase c-Jun N-terminal kinase (JNK), subsequently stabilizing and increasing the transcriptional activity of p53 by phosphorylating it at Thr81; it also enhanced the expression and activity of DNA methyltransferase 1 (DNMT1). ANT2 shRNA-induced overexpression of DR4/DR5 and TRAIL sensitization were blocked by a p53 inhibitor, suggesting that p53 activation plays an important role in the transcriptional up-regulation of DR4/DR5. However, ANT2 knockdown also up-regulated DR4/DR5 in the p53-mutant cell lines BT474 and T47 D. In MCF7 cells, ANT2 shRNA treatment led to DcR2 promoter methylation and concomitant down-regulation of DcR2 expression, consistent with the observed activation of DNMT1. Treatment of the cells with a demethylating agent or JNK inhibitor prevented the ANT2 shRNA-induced down-regulation of DcR2 and activation of both p53 and DNMT1. In in vivo experiments using nude mice, ANT2 shRNA caused TRAIL-resistant MCF7 xenografts to undergo TRAIL-induced cell death, up-regulated DR4/DR5, and down-regulated DcR2. Co-treatment with ANT2 shRNA and TRAIL efficiently suppressed tumor growth in these mice.

CONCLUSIONS:

ANT2 suppression by shRNA might be exploited to overcome TRAIL-resistance in cancer.

• Authors: Ji-Young Jang, Yoon-Kyung Jeon, Yun Choi, Chul-Woo Kim
• Journal: Molecular cancer (Mol Cancer) Vol. 9 Pg. 262 (Sep 28 2010) ISSN: 1476-4598 [Electronic] England
• PMID: 20875141 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Adenine Nucleotide Translocator 2
• Receptors, TNF-Related Apoptosis-Inducing Ligand
• TNF-Related Apoptosis-Inducing Ligand
• TNFRSF10D protein, human
• Tumor Necrosis Factor Decoy Receptors
• DNA (Cytosine-5-)-Methyltransferase 1
• DNA (Cytosine-5-)-Methyltransferases
• DNMT1 protein, human
• Dnmt1 protein, mouse
• JNK Mitogen-Activated Protein Kinases

Topics

• Adenine Nucleotide Translocator 2 (genetics, metabolism)
• Animals
• Apoptosis (drug effects, genetics)
• Breast Neoplasms (drug therapy, genetics, metabolism)
• Cell Line, Tumor
• Cell Survival (drug effects, genetics)
• DNA (Cytosine-5-)-Methyltransferase 1
• DNA (Cytosine-5-)-Methyltransferases (genetics, metabolism)
• Female
• Genetic Vectors
• Humans
• Immunoblotting
• JNK Mitogen-Activated Protein Kinases (genetics, metabolism)
• Mice
• Mice, Nude
• Polymerase Chain Reaction
• Receptors, TNF-Related Apoptosis-Inducing Ligand (genetics, metabolism)
• TNF-Related Apoptosis-Inducing Ligand (therapeutic use)
• Tumor Necrosis Factor Decoy Receptors (genetics, metabolism)