title: Sensitivity to CPT-11 of xenografted human colorectal cancers as a function of microsatellite instability and p53 status.
abstract: Biological parameters influencing the response of human colorectal cancers (CRCs) to CPT-11, a topoisomerase 1 (top1) inhibitor, were investigated using a panel of nine CRCs xenografted into nude mice. CRC xenografts differed in their p53 status (wt or muf) and in their microsatellite instability phenotype (MSI+ when altered). Five CRC xenografts were established from clinical samples. All five had a functional p53, two were MSI+ and three were MSI-. Tumour-bearing nude mice were treated intraperitonealy (i.p.) with CPT-11. At 10 mg kg(-1) of CPT-11, four injections at 4-day intervals, four of the five xenografts responded to CPT-11 (growth delay of up to 10 days); the non-responder tumour was MSI-. At 40 mg kg(-1) of CPT-11, six injections at 4-day intervals, the five CRCs displayed variable but marked responses with complete regressions. In order to assess the role of p53 status in CPT-11 response, four CRC lines were used. HT29 cell line was MSI-/Ala273-mutp53, its subclone HT29A3 being transfected by wtp53. LoVo cell line was MSI+/wtp53, its subclone X17LoVo dominantly expressed Ala273-mutp53 after transfection. LoVo tumours (MSI+/mutp53) were more sensitive than X17LoVo (MSI+/mutp53. HT 29 tumours (MSI-Imutp53), were refractory to CPT-11 while HT29A3 tumours (MSI-/wtp53) were sensitive, showing that wtp53 improves the drug-response in these MSI- tumours. Levels of mRNA expression of top1, fasR, TP53 and mdr1 were semi-quantified by reverse transcription polymerase chain reaction. None of these parameters correlated with CPT-11 response. Taken together, these observations indicate that MSI and p53 alterations could be associated with different CPT-11 sensitivities; MSI phenotype moderately influences the CPT-11 sensitivity, MSI+ being more sensitive than MSI(-)CRC freshly obtained from patients, mutp53 status being associated with a poor response to CPT-11.
authors.affiliation: Institut Curie, UMR 147 CNRS-Institut Curie, Paris, France.
authors.forename: R A
authors.initials: RA
authors.lastname: Bras-Gonçalves
authors.forename: C
authors.initials: C
authors.lastname: Rosty
authors.forename: P
authors.initials: P
authors.lastname: Laurent-Puig
authors.forename: P
authors.initials: P
authors.lastname: Soulié
authors.forename: B
authors.initials: B
authors.lastname: Dutrillaux
authors.forename: M F
authors.initials: MF
authors.lastname: Poupon
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D001483:Base Sequence; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology*; D017931:DNA Primers; D005260:Female; D006801:Humans; D000077146:Irinotecan; D008297:Male; D051379:Mice; D008819:Mice, Nude; D018895:Microsatellite Repeats / Q000235:genetics*; D009154:Mutation; D010641:Phenotype; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D017931:DNA Primers; D016159:Tumor Suppressor Protein p53; D000077146:Irinotecan; D002166:Camptothecin