Regrowth of 5-fluorouracil-treated human colon cancer cells is prevented by the combination of interferon γ, indomethacin, and phenylbutyrate

Yicong Huang, Curt M. Horvath, Samuel Waxman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


We previously reported that phenylbutyrate (PB), a differentiation agent, retarded the regrowth of fluoropyrimidine-treated HT29 cells to a greater extent in a well-differentiated subclone as compared with a poorly differentiated subclone (Y. Huang and S. Waxman, Clin. Cancer Res., 4: 2503- 2509, 1998). To extend these results and to overcome the known heterogeneity of human colon carcinoma (HCC) cells, the effect of cytostatic agents reported to inhibit HCC growth [IFN-α and IFN-γ, indomethacin, and PB alone or in combination] on clonogenicity and HCCs recovery from 5-fluorouracil (FUra) treatment was studied in eight different HCCs. IFN-α proved to be ineffective in all eight HCCs, whereas IFN-γ induced marked growth inhibition in four HCCs that expressed wild-type K-ras. Despite large differences in HCC response to the other individual agents, strong growth inhibition was observed when PB was added in combination with indomethacin. The inhibition was even more pronounced when IFN-γ was included in the regimen. Most importantly, after treatment with the combination of three agents, the clonogenic potential was severely inhibited (92-100%) in the IFN- γ-sensitive cell lines, whereas in the IFN-ψ-insensitive cell lines, comparable loss of clonogenecity was obtained when the cells were pretreated with FUra. As known and described in detail, the three cytostatic agents inhibit different processes necessary for cell growth, thus requiring the cells to repair multiple pathways to restore growth. The induction of STAT1 DNA binding activity by IFN-γ and p21(WAF1) by PB, alone or in combination, correlated with growth inhibition and loss of clonogenicity. The finding that the readily reversible growth inhibition and decrease in clonogenicity of FUra-treated HCC are prolonged by subsequent treatment with the three cytostatic agents in all HCCs may be of clinical importance because FUra continues to be the most widely used cytotoxic agent in the treatment of colon carcinoma.

Original languageEnglish (US)
Pages (from-to)3200-3206
Number of pages7
JournalCancer Research
Issue number12
StatePublished - Jun 15 2000

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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