Folate receptors (FR) which mediate cellular folate uptake in cervical carcinoma (HeLa-IU1) cells are inversely regulated by extracellular folate concentrations. However, there is a dearth of information on underlying mechanisms. The applicants have recently identified that post-transcriptional modulation of FR-alpha mRNA synthetic rates is the dominant mechanism underlying up- and down-regulation of FR in these cells. Furthermore, the interaction of an 18-base cis-element in the 5'-UTR of FR-alpha mRNA and a cytosolic 46-kDa trans-factor (46 kDa TF*) is critical for translation of FR mRNA in vitro because an 18-mer antisense DNA to the cis-element abolishes translation. A model to explain the inverse translational regulation of FR by folates is that the absence of folates promotes maximal interaction of the 18-base cis-element and 46 kDa TF*, and this leads to optimal translation of FR mRNA into FR and consequent up-regulation of FR. Conversely, in folate replete states, down-regulation of FR is accomplished by folate-mediated reduction in the affinity of interaction of the cis-element and trans-factor, and this in turn leads to a reduction in FR mRNA translation. The applicant proposes four inter-related hypothesis-driven specific aims to comprehensively test this model. The applicant will first isolate and characterize the 46 kDA TF* from HeLa-IU1 cells and determine the role of folates in modulating the interaction of the cis-element and 46-kDA-TF* within the context of translation of FR mRNA. Second, he will determine if transient or stable (long-term) expression of the 18-mer antisense DNA in HeLa-IU1 cells has effects on the synthesis of FR under conditions of limiting and excess extracellular folate, an whether this leads to megaloblastosis and premature cell death in vitro and in vivo. Third, he will test the hypothesis that down-regulation of FR can be experimentally induced in cervical carcinoma cells by stable adeno-associated virus 2 (AAV)-mediated transduction and over-expression of the antisense cDNA of the 46 kDA TF*; this will necessitate molecular cloning of the 46 kDa TF* cDNA. Finally, because there is also an interaction of the FR-alpha mRNA cis-element with nuclear trans-factors (nucTF) in HeLa-IU1 cells, the applicant will test the hypothesis that this protein is structurally and functionally distinct from the cytoplasmic 46 kDa TF* in these cells. Together, these studies will help to develop a comprehensive model for the translational regulation of FR. This knowledge will likely lead to new methods of enhancing cytotoxicity toward cervical carcinoma through the application of molecular medicine to exploit the FR metabolic pathway.

National Institute of Health (NIH)
National Cancer Institute (NCI)
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Experimental Therapeutics Subcommittee 1 (ET)
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Forry, Suzanne L
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Indiana University-Purdue University at Indianapolis
Internal Medicine/Medicine
Schools of Medicine
United States
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Xiao, Suhong; Hansen, Deborah K; Horsley, Elizabeth T M et al. (2005) Maternal folate deficiency results in selective upregulation of folate receptors and heterogeneous nuclear ribonucleoprotein-E1 associated with multiple subtle aberrations in fetal tissues. Birth Defects Res A Clin Mol Teratol 73:6-28
Antony, Ayyok; Tang, Ying-Sheng; Khan, Rehana A et al. (2004) Translational upregulation of folate receptors is mediated by homocysteine via RNA-heterogeneous nuclear ribonucleoprotein E1 interactions. J Clin Invest 113:285-301
Yalowitz, Joel A; Xiao, Suhong; Biju, Mangatt P et al. (2004) Characterization of human brain nicotinamide 5'-mononucleotide adenylyltransferase-2 and expression in human pancreas. Biochem J 377:317-26
Zhang, Yonghua; Guo, Lili; Roeske, Roger W et al. (2004) Pteroyl-gamma-glutamate-cysteine synthesis and its application in folate receptor-mediated cancer cell targeting using folate-tethered liposomes. Anal Biochem 332:168-77
Antony, Ayyok C (2004) Folate receptors: reflections on a personal odyssey and a perspective on unfolding truth. Adv Drug Deliv Rev 56:1059-66
Antony, Ayyok C (2003) Vegetarianism and vitamin B-12 (cobalamin) deficiency. Am J Clin Nutr 78:3-6
Pillai, M R; Chacko, P; Kesari, L A et al. (2003) Expression of folate receptors and heterogeneous nuclear ribonucleoprotein E1 in women with human papillomavirus mediated transformation of cervical tissue to cancer. J Clin Pathol 56:569-74
Xiao, X; Tang, Y S; Mackins, J Y et al. (2001) Isolation and characterization of a folate receptor mRNA-binding trans-factor from human placenta. Evidence favoring identity with heterogeneous nuclear ribonucleoprotein E1. J Biol Chem 276:41510-7
Antony, A C; Hansen, D K (2000) Hypothesis: folate-responsive neural tube defects and neurocristopathies. Teratology 62:42-50
Sun, X L; Jayaram, H N; Gharehbaghi, K et al. (1999) Modulation of the cytotoxicity of 3'-azido-3'-deoxythymidine and methotrexate after transduction of folate receptor cDNA into human cervical carcinoma: identification of a correlation between folate receptor expression and thymidine kinase activity. Cancer Res 59:940-6

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