Bombesin-mediated AP-1 activation in a human gastric cancer (SIIA)

H. J. Kim, B. M. Evers, Y. Guo, N. A. Banker, Mark Hellmich, Courtney Townsend

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Abstract

Background. Bombesin, a gut tetradecapeptide homologous to the mammalian gastrin-releasing peptide (GRP), stimulates the growth of the human gastric cancer line SIIA through specific GRP receptors (GRP-Rs); the cellular mechanisms are not known. The purpose of our study was to (1) confirm functional GRP-R in SIIA and (2) determine whether bombesin alters the expression and binding activity of the AP-1 transcription factors, c-jun and jun-B. Methods. SIIA cells were treated with bombesin, and intracellular calcium mobilization was measured by means of fura-2 spectrofluorometry. To assess changes in c-jun and jun-B, RNA and protein were extracted for Northern and Western blots, respectively; nuclear protein was extracted for gel mobility shifts to determine AP-1 binding activity. Results. SIIA cells mobilized intracellular calcium in response to bombesin, exhibiting a functional cell-surface GRP-R. Bombesin treatment increased expression op both c-jun and jun-B mRNA by 0.5 hours, with maximal expression at 1 hour; concomitant increases in steady-state levels of c-Jun and JunB protein were identified. Moreover, bombesin increased binding of the AP-1 proteins as shown by gel shifts. Conclusions. The SIIA human gastric cancer possesses functional GRP-R coupled to the calcium second messenger pathway. Further, bombesin stimulates expression of c-jun and jun-B mRNA and protein and increases binding activity of AP-1 proteins. Delineating the cellular pathways involved in bombesin-mediated gene activation will provide important insights into the mechanisms responsible for normal and neoplastic gut growth.

Original languageEnglish (US)
Pages (from-to)130-137
Number of pages8
JournalSurgery
Volume120
Issue number2
StatePublished - 1996

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ASJC Scopus subject areas

  • Surgery

Cite this

Kim, H. J., Evers, B. M., Guo, Y., Banker, N. A., Hellmich, M., & Townsend, C. (1996). Bombesin-mediated AP-1 activation in a human gastric cancer (SIIA). Surgery, 120(2), 130-137.