Synergistic Anticancer Activity of Arsenic Trioxide with Erlotinib Is Based on Inhibition of EGFR-Mediated DNA Double-Strand Break Repair

Abstract

Arsenic trioxide (ATO), one of the oldest remedies used in traditional medicine, was recently rediscovered as an anticancer drug and approved for treatment of relapsed acute promyelocytic leukemia. However, its activity against nonhematologic cancers is rather limited so far. Here, we show that inhibition of ATO-mediated EGF receptor (EGFR) activation can be used to potently sensitize diverse solid cancer types against ATO. Thus, combination of ATO and the EGFR inhibitor erlotinib exerted synergistic activity against multiple cancer cell lines. Subsequent analyses revealed that this effect was based on the blockade of ATO-induced EGFR phosphorylation leading to more pronounced G 2 -M arrest as well as enhanced and more rapid induction of apoptosis. Comparable ATO-sensitizing effects were also found with PI3K/AKT and mitogen-activated protein/extracellular signal-regulated kinase (MEK) inhibitors, suggesting an essential role of the EGFRmediated downstream signaling pathway in cancer cell protection against ATO. H2AX staining and comet assay revealed that erlotinib significantly increases ATO-induced DNA double-strand breaks (DSB) well in accordance with a role of the EGFR signaling axis in DNA damage repair. Indeed, EGFR inhibition led to downregulation of several DNA DSB repair proteins such as Rad51 and Rad50 as well as reduced phosphorylation of BRCA1. Finally, the combination treatment of ATO and erlotinib was also distinctly superior to both monotreatments against the notoriously therapy-resistant human A549 lung cancer and the orthotopic p31 mesothelioma xenograft model in vivo. In conclusion, this study suggests that combination of ATO and EGFR inhibitors is a promising therapeutic strategy against various solid tumors harboring wild-type EGFR. Mol Cancer Ther; 12(6); 1073-84. Ó2013 AACR.

Cotylenin A and arsenic trioxide cooperatively suppress cell proliferation and cell invasion activity in human breast cancer cells

“…In addition to APL, the antitumor activity of ATO has been reported in a variety of solid tumor cell lines including breast, esophageal, cervical, lung, liver, prostate and liver carcinoma (8)(9)(10)(11)(12)(13). However, it was reported that many solid tumors are less sensitive to ATO than APL.…”

“…It is now well established that ATO induces complete remission in 80-90% of newly diagnosed patients with APL, as well as in 60-90% of all-trans retinoic acid refractory patients (5)(6)(7). Furthermore, the anticancer activity of ATO was also intensively studied in various other hematological malignancies and several solid tumors, including breast cancer (8)(9)(10)(11)(12)(13). Although ATO is very effective in the treatment of APL, ATO has been less successful in other malignancies at tolerable doses.…”

Increased Growth-Inhibitory and Cytotoxic Activity of Arsenic Trioxide in Head and Neck Carcinoma Cells with Functional p53 Deficiency and Resistance to EGFR Blockade

“…The effects of ATO alone and its combination with irradiation (IR) on clonogenic survival, cell cycle progression and apoptosis were evaluated in a panel of p53-deficient and -proficient SCCHN cell lines. Since ATO treatment has also been shown to activate the EGFR pathway [17], to interfere with surface EGFR expression levels [18] and to modulate EGFR-mediated DNA double-strand break repair [19] we also assessed the growth-inhibitory activity of ATO in a SCCHN cell line model of acquired cetuximab resistance. In addition, potential cross-resistance between ATO and cisplatin was evaluated.…”

Mechanism of the inhibition of leukemia cell growth and induction of apoptosis through the activation of ATR and PTEN by the topoisomerase inhibitor 3EZ, 20Ac-ingenol

“…H2AX phosphorylation was clearly induced by these DSBs after 3 h of treatment with CPT [13]. It has been reported that ATO induces DSBs by producing reactive oxygen species (ROS) and forming H2AX phosphorylation and/or DNA fragmentation [40,41]. However, this DNA damage was delayed and was only detectable after 12-24 h. ATO does not induce the formation of topoisomerase I cleavable complex (topo I cc), even though the presence of these complexes reflects alterations of DNA structures induced by caspase-3 activity and ROS-mediated DNA damage [42].…”

“…Although the mechanism by which catalytic inhibitors of topoisomerase II induce phosphorylation involves H2AX and the p53 response to DSBs, the details of these mechanisms remain unclear. Moreover, the analogous mechanisms of catalytic inhibitors of topoisomerase I are also poorly characterized, but the formation mechanism of DSBs by treatment with topoisomerase I poison CPT and DNA damaging agent arsenic trioxide (ATO) has been extensively studied [12,16,[40][41][42][43]. H2AX is phosphorylated in response to DNA DSBs [14], and CPT stabilizes the DNA cleavable complex and blocks the subsequent rejoining of DNA breaks.…”