A vasoactive intestinal peptide receptor analog alters the expression of homeobox genes Ruth A. Steingart a , Eitan Heldenberg a , Albert Pinhasov a , Douglas E. Brenneman b , Mati Fridkin c , Illana Gozes a, * a Department of Clinical Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel b Section on Developmental and Molecular Pharmacology, Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA c Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel Received 19 April 2002; accepted 7 June 2002 Abstract A lipophilic analog of vasoactive intestinal peptide (VIP), stearyl-Nle 17 -neurotensin 6 – 11 VIP 7–28 (SNH), that inhibited lung cancer growth, has been previously described. The mechanism of SNH inhibition of cancer growth is still being elucidated. The present study examined the effects of SNH on homeobox genes in the colon cancer cell line HT 29 that expresses VIP receptors. Homeobox genes contain a characteristic DNA sequence, coding for a stretch of 61 amino acid homeodomain that binds specific DNA motifs. While the HOX gene family contains a single homeodomain, the POU gene family contains an additional DNA binding homeodomain. HT 29 cells were incubated with SNH; RNA was extracted and subjected to reverse-transcription-polymerase chain reaction (RT- PCR) with primers that matched the conserved area of the various HOX or POU genes. The PCR products that were altered by SNH treatment were sequenced. Three candidate SNH-responsive genes, the HOX A4, the HOX B5 and the PUO V transcription factor I (Oct-3) were identified. Semi-quantitative RT-PCR with specific primers confirmed the increase in HOX A4 and the decrease in Oct-3 expression levels following SNH treatment. Thus, the HOX A4 and the Oct-3 homeobox genes may partially mediate SNH activity on cancer cells. D 2002 Elsevier Science Inc. All rights reserved. Keywords: HT 29 cell line; Vasoactive intestinal peptide (VIP); Stearyl-Nle 17 -neurotensin 6 – 11 VIP 7 – 28 (SNH); Homeobox genes 0024-3205/02/$ - see front matter D 2002 Elsevier Science Inc. All rights reserved. PII:S0024-3205(02)02082-9 * Corresponding author. Tel.: +972-3-6407240; fax: +972-3-6408541. E-mail address: igozes@post.tau.ac.il (I. Gozes). www.elsevier.com/locate/lifescie Life Sciences 71 (2002) 2543 – 2552