Mutational analysis of Chk1, Chk2, Apaf1 and Rb1 in human malignant melanoma cell lines

Papp, Thilo; Niemetz, Annett; Dosdahl, Nils; Kumar, Krishan; Schiffmann, Dietmar

doi:10.3892/or.17.1.135

Cited by 9 publications

(14 citation statements)

References 34 publications

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“…It was also shown that CHK1 and CHK2 expression was downregulated by promoter hypermethylation in glioma (51). Mutations in genes encoding both proteins were also found in metastasized melanoma cells (54).…”

Section: Discussionmentioning

confidence: 95%

Contribution of ATM and ATR to the Resistance of Glioblastoma and Malignant Melanoma Cells to the Methylating Anticancer Drug Temozolomide

Eich

Roos

Nikolova

et al. 2013

Molecular Cancer Therapeutics

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The major cytotoxic DNA adduct induced by temozolomide and other methylating agents used in malignant glioma and metastasized melanoma therapy is O 6 -methylguanine (O 6 -MeG). This primary DNA damage is converted by mismatch repair into secondary lesions, which block replication and in turn induce DNA double-strand breaks that trigger the DNA damage response (DDR). Key upstream players in the DDR are the phosphoinositide 3-kinases ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3 related (ATR). Here, we addressed the question of the importance of ATM and ATR in the cell death response following temozolomide. We show that (i) ATM-and ATR-mutated cells are hypersensitive to temozolomide, (ii) O 6 -MeG triggers ATM and ATR activation, (iii) knockdown of ATM and ATR enhances cell kill in gliobalstoma and malignant melanoma cells with a stronger and significant effect in ATR knockdown cells, (iv) ATR, but not ATM, knockdown abolished phosphorylation of H2AX, CHK1, and CHK2 in glioma cells, and (v) temozolomide-induced cell death was more prominently enhanced by pharmacologic inhibition of CHK1 compared with CHK2. The data suggest that ATM and, even better, ATR inhibition is a useful strategy in sensitizing cancer cells to temozolomide and presumably also other anticancer drugs.

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Section: Discussionmentioning

confidence: 95%

Contribution of ATM and ATR to the Resistance of Glioblastoma and Malignant Melanoma Cells to the Methylating Anticancer Drug Temozolomide

Eich

Roos

Nikolova

et al. 2013

Molecular Cancer Therapeutics

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“…On the other hand changes present only in invasive melanomas are probably responsible for tumor invasion and eventual metastasis. Presence of characteristic deletion of 13q that contains tumor suppressor gene Rb1 is interesting, as the Rb1 gene has been shown to be lost in some melanoma cell lines and is known contributing to dysfunctional p53 pathway 28 . Also, Rb1 was shown to be involved in melanocytic proliferation and pigmentation defect in vivo 29 .…”

Section: Discussionmentioning

confidence: 99%

“…Presence of characteristic deletion of 13q that contains tumor suppressor gene Rb1 is interesting, as the Rb1 gene has been shown to be lost in some melanoma cell lines and is known contributing to dysfunctional p53 pathway. 28 Also, Rb1 was shown to be involved in melanocytic proliferation and pigmentation defect in vivo. 29 We propose that deletion or mutation of Rb1 might be one of the earliest events in the development of melanoma.…”

Section: Discussionmentioning

confidence: 99%

Comparative genome hybridization analysis of laser‐capture microdissected in situ melanoma

Vincek

Fan

2009

J Cutan Pathol

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“…These results demonstrated that SNX-2112 mediates the degradation of Hsp90 client proteins and attenuates Akt/GSK3β, IKKα/NF-κB and MAPK signaling. Inhibition of these proteins is associated with reduced proliferation of melanoma cells (25)(26)(27)(28)(29). Both the Ras/Raf/MEK/Erk (MAPK) and the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathways are constitutively activated via multiple mechanisms in melanoma (30,31).…”

Section: Discussionmentioning

confidence: 99%

The heat shock protein 90 inhibitor SNX-2112 inhibits B16 melanoma cell growth in vitro and in vivo

et al. 2012

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Abstract. SNX-2112 is a selective heat shock protein 90 (Hsp90) inhibitor which can exert a potent anticancer activity. In this study, we investigated the effects of SNX-2112 on B16 melanoma cells in vitro and in vivo. The 3-(4,5-dimetrylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometric analysis demonstrated that SNX-2112 dosedependently inhibited the growth of B16 cells, and induced G0/ G1 cell cycle arrest and apoptosis. Western blotting revealed that SNX-2112 lead to the degradation of Hsp90 client proteins including Akt, IKKα, NF-κB, B-Raf and GSK3β. Furthermore, we assessed the antitumor effect of SNX-2112 in vivo, using a xenograft model in C57BL/6 mice. Oral administration of SNX-2112 significantly inhibited the growth of B16 tumors in mice, with a 47% inhibition observed at dose of 80 mg/kg/day for 15 days, compared to control tumors. Hematoxylin-eosin (H&E) staining of xenograft tissues showed that SNX-2112 also inhibited angiogenesis and lead to a lower blood vessel density in the tumors, compared to the control group. These findings demonstrate that SNX-2112 can exhibit a potent anticancer activity against B16 melanoma cells both in vitro and in vivo, by inhibiting cell proliferation and inducing cell cycle arrest and apoptosis in a mechanism dependent on the degradation of Hsp90 client proteins. IntroductionHsp90 is an important ATP-dependent molecular chaperone required for protein folding, as well as the assembly and maintenance of the conformational stability of a diverse range of client proteins. Hsp90 client proteins play key roles in cellular metabolism, trafficking, signal transduction, chromatin remodeling, cell growth and differentiation (1-4). Hsp90 client proteins include cell survival and proliferation regulators, such as Akt, IKK, Raf, GSK3 and NF-κB (5-7). Hsp90 is overexpressed in tumor cells compared to their normal counterparts (8), and inhibition of Hsp90 has been considered as a possible strategy for the treatment of cancer.Currently, 14 drug candidates which target Hsp90 are undergoing clinical trials for multiple indications, either as single agents or in combination therapy, including 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), 17-allylamino-17-demethoxygeldanamycin hydroquinone hydrochloride (IPI-504) and BIIB021 (9). 17-AAG was the first Hsp90 inhibitor to undergo phase III clinical trials, and is well tolerated and has a good therapeutic efficacy. However, 17-AAG has several potential limitations, including poor solubility, limited bioavailability and unsatisfactory hepatotoxicity (10-12). This has led to efforts to identify new, safer and more effective Hsp90 inhibitors for clinical applications.SNX-2112, a selective Hsp90 inhibitor, can bind to the N-terminal adenosine triphosphate binding site of Hsp90 and can exert significant growth inhibition of various cancer cell lines both in vitro and in vivo (13,14). In our previous research, SNX-2112 displayed promising anti-tumor activity in human chronic leukemia 16). In addition, SNX-2112 is ...

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Mutational analysis of Chk1, Chk2, Apaf1 and Rb1 in human malignant melanoma cell lines

Cited by 9 publications

References 34 publications

Contribution of ATM and ATR to the Resistance of Glioblastoma and Malignant Melanoma Cells to the Methylating Anticancer Drug Temozolomide

Contribution of ATM and ATR to the Resistance of Glioblastoma and Malignant Melanoma Cells to the Methylating Anticancer Drug Temozolomide

Comparative genome hybridization analysis of laser‐capture microdissected in situ melanoma

The heat shock protein 90 inhibitor SNX-2112 inhibits B16 melanoma cell growth in vitro and in vivo

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