Differential activation of IGF-II promoters P3 and P4 in Caco-2 cells during growth and differentiation

Pomila Singh, B. Dai, R. L. Given, X. Lu, P. E. Holthuizen

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Background and Aims: Insulin-like growth factor (IGF)-II gene is overexpressed in colon cancers. Transcriptional up-regulation may be the major mechanism contributing to its overexpression. IGF-II messenger RNA (mRNA) levels are up-regulated during proliferation followed by a significant decline during differentiation of Caco-2 cells. Mechanisms underlying transcriptional regulation of the IGF-II gene promoters (P1-P4) have yet to be examined in colon cancers, which was the basis for this study. Methods: Ribonuclease protection assay was used to measure IGF-II mRNA derived from P1-P4. To determine if changes in the IGF-II transcripts reflected differences in promoter activity, transient transfection assays with the full-length P1-P4-luciferase expression vectors were performed. Results: Both P3- and P4-derived transcripts were significantly up-regulated during the proliferative phase of the cells (days 3-6 in culture) and declined rapidly in cells undergoing differentiation (days 7-10); conversely, P1- and P2- derived transcripts were not detected. Similarly, transcriptional activity of P3 and P4 promoters reached peak levels by days 4-6 and declined rapidly thereafter. P1 and P2 were relatively inactive on all days. Conclusions: The activity of the P3 and P4 promoters may play a selective role in regulating IGF-II mRNA levels during growth and differentiation of colon cancer cells.

Original languageEnglish (US)
Pages (from-to)1221-1229
Number of pages9
JournalGastroenterology
Volume114
Issue number6
DOIs
StatePublished - 1998

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Insulin-Like Growth Factor II
Caco-2 Cells
Growth
Colonic Neoplasms
Messenger RNA
Ribonucleases
Luciferases
Genes
Transfection
Cell Differentiation
Up-Regulation

ASJC Scopus subject areas

  • Gastroenterology

Cite this

Differential activation of IGF-II promoters P3 and P4 in Caco-2 cells during growth and differentiation. / Singh, Pomila; Dai, B.; Given, R. L.; Lu, X.; Holthuizen, P. E.

In: Gastroenterology, Vol. 114, No. 6, 1998, p. 1221-1229.

Research output: Contribution to journalArticle

Singh, Pomila ; Dai, B. ; Given, R. L. ; Lu, X. ; Holthuizen, P. E. / Differential activation of IGF-II promoters P3 and P4 in Caco-2 cells during growth and differentiation. In: Gastroenterology. 1998 ; Vol. 114, No. 6. pp. 1221-1229.
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AB - Background and Aims: Insulin-like growth factor (IGF)-II gene is overexpressed in colon cancers. Transcriptional up-regulation may be the major mechanism contributing to its overexpression. IGF-II messenger RNA (mRNA) levels are up-regulated during proliferation followed by a significant decline during differentiation of Caco-2 cells. Mechanisms underlying transcriptional regulation of the IGF-II gene promoters (P1-P4) have yet to be examined in colon cancers, which was the basis for this study. Methods: Ribonuclease protection assay was used to measure IGF-II mRNA derived from P1-P4. To determine if changes in the IGF-II transcripts reflected differences in promoter activity, transient transfection assays with the full-length P1-P4-luciferase expression vectors were performed. Results: Both P3- and P4-derived transcripts were significantly up-regulated during the proliferative phase of the cells (days 3-6 in culture) and declined rapidly in cells undergoing differentiation (days 7-10); conversely, P1- and P2- derived transcripts were not detected. Similarly, transcriptional activity of P3 and P4 promoters reached peak levels by days 4-6 and declined rapidly thereafter. P1 and P2 were relatively inactive on all days. Conclusions: The activity of the P3 and P4 promoters may play a selective role in regulating IGF-II mRNA levels during growth and differentiation of colon cancer cells.

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