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dc.contributor.authorBrown, R
dc.contributor.authorHirst, G L
dc.contributor.authorGallagher, W M
dc.contributor.authorMcIlwrath, A J
dc.contributor.authorMargison, Geoffrey P
dc.contributor.authorVan der Zee, A G
dc.contributor.authorAnthoney, D A
dc.date.accessioned2010-03-30T11:44:43Z
dc.date.available2010-03-30T11:44:43Z
dc.date.issued1997-07-03
dc.identifier.citationhMLH1 expression and cellular responses of ovarian tumour cells to treatment with cytotoxic anticancer agents. 1997, 15 (1):45-52 Oncogeneen
dc.identifier.issn0950-9232
dc.identifier.pmid9233776
dc.identifier.doi10.1038/sj.onc.1201167
dc.identifier.urihttp://hdl.handle.net/10541/95253
dc.description.abstractLoss of expression of the hMLH1 and hPMS2 subunits of the MutL alpha-mismatch repair complex is a frequent event (9/10) in independent cisplatin resistant derivatives of a human ovarian carcinoma cell line. However, only hMLH1 mRNA is decreased in these MutL alpha-deficient lines. No alterations in the levels of the hMSH2 and hMSH6 (GTBP) subunits of the MutS alpha-complex are observed. An increase in the proportion of ovarian tumours negative for the hMLH1 subunit is observed in samples taken at second look laparotomy after chemotherapy (36%: 4/11), compared to untreated tumours (10%: 4/39). No significant difference is observed for hMSH2, hMSH6 or hPMS2. Furthermore, cisplatin and doxorubicin-resistant ovarian lines deficient in hMLH1 expression are cross-resistant to 6-thioguanine and the methylating agent N-methyl-N-nitrosourea (MNU). Depletion of O6-alkylguanine-DNA-alkyltransferase (ATase) activity confers only limited increased sensitivity to MNU. Thus the mismatch repair deficient lines retain DNA damage tolerance even after ATase depletion. The hMLH1 deficient lines also lose ability to engage G1 and G2 cell cycle arrest after cisplatin damage. Together these data suggest that loss of hMLH1 expression may be a high frequency event following exposure of ovarian tumour cells to cisplatin and may be critically involved in the development of drug resistance. Thus, the hMLH1 status of these cells appears to be highly correlated with the ability to engage cell death and cell cycle arrest after DNA damage induced by cisplatin.
dc.language.isoenen
dc.subjectCancer Drug Resistanceen
dc.subjectCancer Proteinsen
dc.subjectOvarian Canceren
dc.subjectCultured Tumour Cellsen
dc.subject.meshAdaptor Proteins, Signal Transducing
dc.subject.meshAdenosine Triphosphatases
dc.subject.meshAntineoplastic Agents
dc.subject.meshAntineoplastic Agents, Alkylating
dc.subject.meshCarrier Proteins
dc.subject.meshCisplatin
dc.subject.meshDNA Repair
dc.subject.meshDNA Repair Enzymes
dc.subject.meshDNA-Binding Proteins
dc.subject.meshDoxorubicin
dc.subject.meshDrug Resistance, Neoplasm
dc.subject.meshFemale
dc.subject.meshG2 Phase
dc.subject.meshHumans
dc.subject.meshMethylnitrosourea
dc.subject.meshNeoplasm Proteins
dc.subject.meshNuclear Proteins
dc.subject.meshOvarian Neoplasms
dc.subject.meshThioguanine
dc.subject.meshTumor Cells, Cultured
dc.titlehMLH1 expression and cellular responses of ovarian tumour cells to treatment with cytotoxic anticancer agents.en
dc.typeArticleen
dc.contributor.departmentDepartment Medical Oncology, CRC Beatson Laboratories, Glasgow University, UK.en
dc.identifier.journalOncogeneen
html.description.abstractLoss of expression of the hMLH1 and hPMS2 subunits of the MutL alpha-mismatch repair complex is a frequent event (9/10) in independent cisplatin resistant derivatives of a human ovarian carcinoma cell line. However, only hMLH1 mRNA is decreased in these MutL alpha-deficient lines. No alterations in the levels of the hMSH2 and hMSH6 (GTBP) subunits of the MutS alpha-complex are observed. An increase in the proportion of ovarian tumours negative for the hMLH1 subunit is observed in samples taken at second look laparotomy after chemotherapy (36%: 4/11), compared to untreated tumours (10%: 4/39). No significant difference is observed for hMSH2, hMSH6 or hPMS2. Furthermore, cisplatin and doxorubicin-resistant ovarian lines deficient in hMLH1 expression are cross-resistant to 6-thioguanine and the methylating agent N-methyl-N-nitrosourea (MNU). Depletion of O6-alkylguanine-DNA-alkyltransferase (ATase) activity confers only limited increased sensitivity to MNU. Thus the mismatch repair deficient lines retain DNA damage tolerance even after ATase depletion. The hMLH1 deficient lines also lose ability to engage G1 and G2 cell cycle arrest after cisplatin damage. Together these data suggest that loss of hMLH1 expression may be a high frequency event following exposure of ovarian tumour cells to cisplatin and may be critically involved in the development of drug resistance. Thus, the hMLH1 status of these cells appears to be highly correlated with the ability to engage cell death and cell cycle arrest after DNA damage induced by cisplatin.


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