The gene encoding the hormone secretin is expressed only in enteroendocrine S cells and insulinproducing pancreatic ␤ cells during development. A 120-bp enhancer directs cell-specific expression of the rat secretin gene in secretin-expressing cells. The enhancer includes an E-box sequence, CAGCTG, which is important for transcriptional activity. To further characterize the role of the E box, a consensus binding site for basic helix-loop-helix (bHLH) proteins, we have examined factors that interact with this element in the secretin gene. The results suggest that transcription is activated by a recently isolated tissue-specific bHLH protein, BETA2, heterodimerized to the ubiquitously expressed bHLH proteins, Pan 1 and Pan 2, the rodent homologues of E47 and E12. The importance of BETA2 for transcriptional activation of secretin is further illustrated by antisense experiments inhibiting BETA2 expression in secretin-producing cell lines, which resulted in the inhibition of most E box-dependent transcription. Expression of BETA2 in a nonendocrine cell line conferred the ability to express secretin-reporter genes that are transcribed at minimal levels in the absence of BETA2. Secretin-producing enteroendocrine cells in the murine small intestine showed specific immunostaining with BETA2 antibodies, corroborating observations in cell lines. Thus BETA2 is to our knowledge the first transcription factor identified that specifically activates cell type-specific expression of an intestinal hormone gene.

Purpose: Human papillomavirus (HPV)-16 oncoproteins, E6 and E7, are associated with enhanced tumor angiogenesis in human cervical cancers. The purpose of this study was (a) to investigate whether expression of HPV-16 E6 and E7 oncoproteins induces hypoxia-inducible factor 1a (HIF-1a) and vascular endothelial growth factor expression in cervical cancer cells; and (b) to assess the effect of resveratrol on 16 E6-and E7-induced HIF-1a and VEGF gene expression. Experimental Design: Human cervical cancer cell lines C-33A and HeLa were transiently cotransfected with pSG5-HPV-16 E6 or 16 E7 constructs along with HIF-1a small interfering RNA (siRNA) or nonspecific siRNA. The expression of HIF-1a/VEGF was measured using realtime PCR, Western blot analysis, or ELISA. The in vitro angiogenic activity induced by 16 E6-and E7-transfected cells was examined. The effect of resveratrol on oncoprotein-induced HIF-1a/VEGF expression and in vitro angiogenesis was investigated. Results: HPV-16 E6-and E7-transfected cervical cancer cells express increased HIF-1a protein andVEGF expression.These stimulatory effects were abrogated by cotransfection with either HIF1a siRNA or treatment with resveratrol. Blocking extracellular signal-regulated kinase 1/2 (ERK 1/ 2) and phosphoinositide-3-kinase by PD98059 and LY294002, respectively, abolished 16 E6-and E7-induced HIF-1aand VEGF expression. Functionally, we showed that HPV-16 E6-and E7-transfected cervical cancer cells stimulated in vitro capillary or tubule formation, and these angiogenic effects could be abolished either by cotransfection with HIF-1asiRNA or by treatment with resveratrol. Conclusion: HPV-16 oncoproteins contribute to enhanced angiogenesis in cervical cancer cells via HIF-1a^dependentVEGF expression. Resveratrol suppresses 16 E6-and E7-induced HIF-1am ediated angiogenic activity and, thus, is a promising chemotherapeutic agent for human cervical cancer.

Recent epidemiologic studies show increasing human immunodeficiency virus type 1 (HIV-1) transmission through oral-genital contact. This paper examines the possibility that normal human oral keratinocytes (NHOKs) might be directly infected by HIV or might convey infectious HIV virions to adjacent leukocytes. PCR analysis of proviral DNA constructs showed that NHOKs can be infected by CXCR4-tropic (NL4-3 and ELI) and dualtropic (89.6) strains of HIV-1 to generate a weak but productive infection. CCR5-tropic strain Ba-L sustained minimal viral replication. Antibody inhibition studies showed that infection by CXCR4-tropic viral strains is mediated by the galactosylceramide receptor and the CXCR4 chemokine coreceptor. Coculture studies showed that infectious HIV-1 virions can also be conveyed from NHOKs to activated peripheral blood lymphocytes, suggesting a potential role of oral epithelial cells in the transmission of HIV infection.