Apoptotic response to 5-fluorouracil treatment is mediated by reduced polyamines, non-autocrine Fas ligand and induced tumor necrosis factor receptor 2.
5-fluorouracil (5-FU) is the major chemotherapeutic agent for treatment of colorectal carcinoma, but the molecular mechanisms of response and resistance are not understood completely. We therefore studied the 5-FU dose response and time course of gene expression transcriptome changes in colon carcinoma cell lines that are relatively sensitive to or resistant to 5-FU (RKO and HT29, respectively. We identified cellular pathways and corroborated functions of selected pathways. Expression of genes for polyamine biosynthesis, i.e., ornithine decarboxylase (ODC) and spermine and spermidine synthases, was repressed in the sensitive line, while the biosynthesis-inhibiting gene ODC antizyme was induced in the resistant line. The rate-limiting gene in catabolism, spermine/spermidine acetyltransferase, was induced in both lines. Polyamine levels showed corresponding drastic decreases after 5-FU treatment, and polyamine replenishment interfered with 5-FU-induced apoptosis. In the sensitive cells which have wild-type p53, the p53 gene and its downstream genes including p21/WAF1, mdm2, Fas, mic-1, EphA2, and ferredoxin reductase as well as genes in the tumor necrosis factor (TNF) pathway including TNF receptor 2 (TNFR2) were induced, but not Fas ligand (FasL). Exposure to exogenous FasL increased 5-FU-induced apoptosis, and anti-TNFR2 antibody, but not anti-TNFR1, partially protected the sensitive cells. Our combination of gene expression profiling and corroborative functional studies revealed that reduced polyamine levels, non-autocrine FasL originating exogenous to tumor cells, and induced TNFR2 are all functional mediators of apoptosis caused by 5-FU in colon carcinoma cells.
Zhang
Wei
W
Department of Pathology, Division of Pathology and Laboratory Medicine, The University of Texas, M.D. Anderson Cancer Center; Houston, Texas USA.
Ramdas
Latha
L
Shen
Weiping
W
Song
Sonya W
SW
Hu
Limei
L
Hamilton
Stanley R
SR
D000123:Acetyltransferases / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D005472:Fluorouracil / Q000494:pharmacology*; D020869:Gene Expression Profiling; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D009955:Ornithine Decarboxylase / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D047889:Receptors, Tumor Necrosis Factor, Type II; D011436:Spermidine Synthase / Q000378:metabolism; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism*; D000099228:Diamine N-Acetyltransferase
D000123:Acetyltransferases; D015703:Antigens, CD; D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil; D009363:Neoplasm Proteins; D009955:Ornithine Decarboxylase; D011073:Polyamines; D018124:Receptors, Tumor Necrosis Factor; D047889:Receptors, Tumor Necrosis Factor, Type II; D011436:Spermidine Synthase; D016159:Tumor Suppressor Protein p53; D019014:fas Receptor; D000099228:Diamine N-Acetyltransferase