title: Functional inactivity and mutations of p53 differentially affect sensitivity to 5-fluorouracil and antifolate inhibitors of thymidylate synthase (TS) by altering TS levels in colorectal cancer cells.
abstract: The role of p53 in altering TS expression and chemosensitivity was studied in colorectal cancer cells with wildtype, mutated, or functionally inactive p53. Cytotoxicity of TS inhibitors was studied by MTT, while PCR, Western blot, and activity assays assessed whether p53 status influenced TS expression. Lovo-175X2 cells showed increased resistance to TS inhibitors and significantly greater than wildtype expression and activity of TS. In contrast, Lovo-273X17 and Lovo-li were more sensitive to TS inhibitors and had reduced TS expression, due either to reduced TS mRNA or altered regulation of TS activity. Thus, functional inactivity and mutations of p53 differentially affect TS, potentially influencing response to TS inhibitor-based treatment.
authors.affiliation: Department of Medical Oncology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Giovannetti
authors.forename: H H J
authors.initials: HH
authors.lastname: Backus
authors.forename: D
authors.initials: D
authors.lastname: Wouters
authors.forename: G J
authors.initials: GJ
authors.lastname: Peters
mesh_terms: D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005472:Fluorouracil / Q000494:pharmacology*; D005493:Folic Acid Antagonists / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020128:Inhibitory Concentration 50; D009154:Mutation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism
chemical_list: D005493:Folic Acid Antagonists; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D013940:Thymidylate Synthase; D005472:Fluorouracil