Involvement of Rad51 in cytotoxicity induced by epidermal growth factor receptor inhibitor (gefitinib, IressaR) and chemotherapeutic agents in human lung cancer cells

Ko, Jen-Chung; Ciou, Shih‐Ci; Cheng, Chau-Ming; Wang, Lyu-Han; Hong, Jhao-Hao; Jheng, Ming-Yan; Ling, Szu-Ting; Lin, Yun‐Wei

doi:10.1093/carcin/bgn130

Cited by 55 publications

(51 citation statements)

References 65 publications

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“…EGFR is essential for PDAC initiation because its loss in genetically engineered mouse models prevents PDAC development (38)(39)(40). Another important feature of EGFR biology that holds clinical promise for RIT is the inhibition of the noncanonical direct EGFR nuclear translocation pathway (41), which increases repair of DNA DSBs (42)(43)(44)(45), the most lethal of DNA lesions induced by conventional anticancer treatments. We previously reported that EGFR-directed RIT inhibited DNA-PK phosphorylation, a critical protein involved in nonhomologous end joining pathway of DSBs, and caused the degradation of RAD51, a protein involved in HR repair, in models of aggressive breast cancer (16).…”

Section: Discussionmentioning

confidence: 99%

Gemcitabine and CHK1 Inhibition Potentiate EGFR-Directed Radioimmunotherapy against Pancreatic Ductal Adenocarcinoma

Al-Ejeh

Shi

Kalimutho

et al. 2014

Clinical Cancer Research

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Purpose: To develop effective combination therapy against pancreatic ductal adenocarcinoma (PDAC) with a combination of chemotherapy, CHK1 inhibition, and EGFR-targeted radioimmunotherapy.Experimental Design: Maximum tolerated doses were determined for the combination of gemcitabine, the CHK1 inhibitor PF-477736, and Lutetium-177 ( 177 Lu)-labeled anti-EGFR antibody. This triple combination therapy was investigated using PDAC models from well-established cell lines, recently established patient-derived cell lines, and fresh patient-derived xenografts. Tumors were investigated for the accumulation of 177 Lu-anti-EGFR antibody, survival of tumor-initiating cells, induction of DNA damage, cell death, and tumor tissue degeneration.Results: The combination of gemcitabine and CHK1 inhibitor PF-477736 with 177 Lu-anti-EGFR antibody was tolerated in mice. This triplet was effective in established tumors and prevented the recurrence of PDAC in four cell line-derived and one patient-derived xenograft model. This exquisite response was associated with the loss of tumor-initiating cells as measured by flow cytometric analysis and secondary implantation of tumors from treated mice into treatment-na€ ve mice. Extensive DNA damage, apoptosis, and tumor degeneration were detected in the patient-derived xenograft. Mechanistically, we observed CDC25A stabilization as a result of CHK1 inhibition with consequent inhibition of gemcitabine-induced S-phase arrest as well as a decrease in canonical (ERK1/2 phosphorylation) and noncanonical EGFR signaling (RAD51 degradation) as a result of EGFR inhibition. Conclusions: Our study developed an effective combination therapy against PDAC that has potential in the treatment of PDAC.

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Section: Discussionmentioning

confidence: 99%

Gemcitabine and CHK1 Inhibition Potentiate EGFR-Directed Radioimmunotherapy against Pancreatic Ductal Adenocarcinoma

Al-Ejeh

Shi

Kalimutho

et al. 2014

Clinical Cancer Research

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“…In lung cancer, high expression of Rad51 in tumor tissue is associated with an unfavorable prognosis (24). Our recent study has shown that the polycyclic hydrocarbon carcinogen benzo(a)pyrene can enhance the expression of Rad51 through the activation of ERK1/2 (45), and MEK1/2-ERK1/2 is the upstream signaling pathway to regulate the Rad51 expression, which is associated with the resistance to gefitinib, mitomycin C, and cisplatin in NSCLC (25,26).…”

Section: Discussionmentioning

confidence: 99%

“…In lung cancer, high expression of Rad51 in tumor tissue is associated with an unfavorable prognosis (24). Our recent study has shown that the MEK1/2-ERK1/2 is the upstream signaling pathway in regulating the Rad51 expression (25,26). However, the role of Rad51 in regulating the response to erlotinib in different cell types of human NSCLC also remains to be elucidated.…”

Section: Introductionmentioning

confidence: 99%

Roles of MKK1/2-ERK1/2 and Phosphoinositide 3-Kinase–AKT Signaling Pathways in Erlotinib-Induced Rad51 Suppression and Cytotoxicity in Human Non–Small Cell Lung Cancer Cells

Ciou

Jhan

et al. 2009

Molecular Cancer Research

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Erlotinib (Tarceva) is a selective epidermal growth factor receptor tyrosine kinase inhibitor in the treatment of human non-small cell lung cancer (NSCLC). In this study, we investigated the roles of ERK1/2 and AKT signaling pathways in regulating Rad51 expression and cytotoxic effects in different NSCLC cell lines treated with erlotinib. Erlotinib decreased cellular levels of phosphorylated ERK1/2, phosphorylated AKT, Rad51 protein, and mRNA in erlotinib-sensitive H1650, A549, and H1869 cells, leading to cell death via apoptosis, but these results were not seen in erlotinib-resistant H520 and H1703 cells. Erlotinib decreased Rad51 protein levels by enhancing Rad51 mRNA and protein instability. Enforced expression of constitutively active MKK1 or AKT vectors could restore Rad51 protein levels, which were inhibited by erlotinib, and decrease erlotinib-induced cytotoxicity. Knocking down endogenous Rad51 expression by si-Rad51 RNA transfection significantly enhanced erlotinib-induced cytotoxicity. In contrast, overexpression of Rad51 by transfection with Rad51 vector could protect the cells from cytotoxic effects induced by erlotinib. Blocking the activations of ERK1/2 and AKT by MKK1/2 inhibitor (U0126) and phosphoinositide 3-kinase inhibitor (wortmannin) suppressed the expression of Rad51 and enhanced the erlotinib-induced cell death in erlotinib-resistant cells. In conclusion, suppression of Rad51 may be a novel therapeutic modality in overcoming drug resistance of erlotinib in NSCLC. (Mol Cancer Res 2009;7(8):1378-89)

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“…After the different treatments, the cells were rinsed twice with ice-cold phosphate-buffered saline and lysed in whole-cell extraction buffer [20 mM HEPES, pH 7.6, 75 mM NaCl, 2.5 mM MgCl 2 , 0.1 mM EDTA, 0.1% Triton X-100, 0.1 mM Na 3 VO 4 , 50 mM NaF, 1 g/ml leupeptin, 1 g/ml aprotinin, 1 g/ml pepstatin, and 1 mM 4-(2-aminoethyl)benzenesulfonyl fluoride]. Equal amounts of protein from each set of experiments were subjected to Western blot analysis as described previously (Ko et al, 2008a). The relative protein blot intensities were determined using a computing densitometer equipped with the ImageQuant analysis program (GE Healthcare, Chalfont St. Giles, Buckinghamshire, UK).…”

Section: Methodsmentioning

confidence: 99%

“…3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT; Sigma-Aldrich) assays were used to evaluate the inhibitory effects of emodin and MMC on cell viability as described previously (Ko et al, 2008a). In brief, cells were seeded on 96-well plates with RPMI containing 10% fetal calf serum in a final volume of 0.2 ml, incubated for 18 h, and then treated with the drugs for 24 h. After drug treatment, the MTT solution was added to each well and incubated for 3 h before the medium was removed.…”

Section: Methodsmentioning

confidence: 99%

Role of Rad51 Down-Regulation and Extracellular Signal-Regulated Kinases 1 and 2 Inactivation in Emodin and Mitomycin C-Induced Synergistic Cytotoxicity in Human Non–Small-Cell Lung Cancer Cells

Su¹,

Tsai²,

Kuo³

et al. 2009

Mol Pharmacol

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Emodin (1,3,8-trihydroxy-6-methyl-anthraquinone) is a natural anthraquinone derivative found in the roots and rhizomes of numerous plants. It is a tyrosine kinase inhibitor and has anticancer effects on lung cancer. Rad51 plays a central role in homologous recombination, and high levels of Rad51 expression are observed in chemo-or radioresistant carcinomas. Our previous studies have shown that the mitogen-activated protein kinase kinase (MKK) 1/2-extracellular signal-regulated kinase (ERK) 1/2 signal pathway maintains the expression of Rad51. Therefore, in this study, we hypothesized that emodin could enhance the effects of the antitumor antibiotic mitomycin C (MMC)-mediated cytotoxicity by decreasing the expression of Rad51 and the phosphorylation of ERK1/2. Exposure of the human non-small-cell lung cancer H1703 or A549 cell lines to emodin decreased the MMC-elicited phosphorylated ERK1/2 and Rad51 levels. Moreover, emodin significantly decreased the MMC-elicited Rad51 mRNA and protein levels by increasing the instability of Rad51 mRNA and protein. In emodin-and MMC-cotreated cells, ERK1/2 phosphorylation was enhanced by constitutively active MKK1/2 (MKK1/2-CA), thus increasing Rad51 protein levels and protein stability. The synergistic cytotoxic effects induced by emodin combined with MMC were remarkably decreased by MKK1-CA-mediated enhancement of ERK1/2 activation. Depletion of endogenous Rad51 expression by small interfering Rad51 RNA transfection significantly enhanced MMC-induced cell death and cell growth inhibition. In contrast, overexpression of Rad51 protects lung cancer cells from the synergistic cytotoxic effects induced by emodin and MMC. We conclude that suppression of Rad51 expression or a combination of emodin with chemotherapeutic agents may be considered as potential therapeutic modalities for lung cancer.Lung cancer is the leading cause of cancer-related death in the world and can be broadly classified into small cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC) (Bhattacharjee et al., 2001). NSCLC accounts for approximately 85% of all lung cancers (Landis et al., 1999), and unlike SCLC, NSCLC is less sensitive to chemotherapeutic agents; the average 5-year survival rates are 10 to 15% . Mitomycin C (MMC) is an anticancer drug that forms monoadducts and intrastrand cross-links between the N-2 guanines of the d(CpG) sequence in the minor groove of DNA (Warren and Hamilton, 1996;Dronkert and Kanaar, 2001). MMC is typically used as a first-or second-line regimen to treat NSCLC and is often combined with other chemotherapeutic agents during advanced NSCLC treatment (Babiak et al., 2007). The therapeutic value of MMC depends on the ability of cells to remove DNA damage (McHugh et al., 2001).

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Involvement of Rad51 in cytotoxicity induced by epidermal growth factor receptor inhibitor (gefitinib, IressaR) and chemotherapeutic agents in human lung cancer cells

Cited by 55 publications

References 65 publications

Gemcitabine and CHK1 Inhibition Potentiate EGFR-Directed Radioimmunotherapy against Pancreatic Ductal Adenocarcinoma

Gemcitabine and CHK1 Inhibition Potentiate EGFR-Directed Radioimmunotherapy against Pancreatic Ductal Adenocarcinoma

Roles of MKK1/2-ERK1/2 and Phosphoinositide 3-Kinase–AKT Signaling Pathways in Erlotinib-Induced Rad51 Suppression and Cytotoxicity in Human Non–Small Cell Lung Cancer Cells

Role of Rad51 Down-Regulation and Extracellular Signal-Regulated Kinases 1 and 2 Inactivation in Emodin and Mitomycin C-Induced Synergistic Cytotoxicity in Human Non–Small-Cell Lung Cancer Cells

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