Julie Hervé

Long-Term Radioiodine Retention and Regression of Liver Cancer after Sodium Iodide Symporter Gene Transfer in Wistar Rats

Radioiodine therapy of nonthyroid cancers after sodium iodide symporter (NIS) gene delivery has been proposed as a potential application of gene therapy. However, it seems to be precluded by the rapid efflux of taken up iodine from most transduced xenografted tumors. We present an in vivo kinetic study of NIS-related hepatic iodine uptake in an aggressive model of hepatocarcinoma induced by diethylnitrosamine in immunocompetent Wistar rats. We followed the whole-body iodine distribution by repeated imaging of live animals. We constructed a rat NIS (rNIS) adenoviral vector, Ad-CMV-rNIS, using the cytomegalovirus (CMV) as a promoter. Injected in the portal vein in 5 healthy and 25 hepatocarcinoma-bearing rats and liver tumors in 9 hepatocarcinoma-bearing rats, Ad-CMV-rNIS drove expression of a functional NIS protein by hepatocytes and allowed marked (from 20 to 30% of the injected dose) and sustained (>11 days) iodine uptake. This contrasts with the massive iodine efflux found in vitro in human hepatic tumor cell lines. In vivo specific inhibition of NIS by sodium perchlorate led to a rapid iodine efflux from the liver, indicating that the sustained uptake was not attributable to an active retention mechanism but to permanent recycling of the effluent radioiodine via the high hepatic blood flow. Radioiodine therapy after Ad-CMV-rNIS administration achieved a strong inhibition of tumor growth, the complete regression of small nodules, and prolonged survival of hepatocarcinoma-bearing rats. This demonstrates for the first time the efficacy of NIS-based radiotherapy in a relevant preclinical model of nonthyroid human carcinogenesis.

Internal Radiotherapy of Liver Cancer with Rat Hepatocarcinoma-Intestine-Pancreas Gene as a Liver Tumor-Specific Promoter

The hepatocarcinoma-intestine-pancreas (HIP) gene, also called pancreatitis-associated protein-1 (PAP1) or Reg IIIalpha, is activated in most human hepatocellular carcinomas (HCCs) but not in normal liver, which suggests that HIP regulatory sequence could be used as efficient liver tumor-specific promoters to express a therapeutic polynucleotide in liver cancer. The sodium iodide symporter (NIS), which has recognized therapeutic and reporter gene properties, is appropriate to evaluate the transcriptional strength and specificity of the HIP promoter in HCC. For this purpose, we constructed a recombinant rat HIP-NIS adenoviral vector (AdrHIP-NIS), and evaluated its performance as a mediator of selective radioiodide uptake in tumor hepatocytes. Western blot, immunofluorescence, and iodide uptake assays were performed in AdrHIP-NIS-infected primary hepatocytes and transformed hepatic and nonhepatic cells. Nuclear imaging, tissue counting and immunohistochemistry were performed in normal and HCC-bearing Wistar rats infected with AdrHIP-NIS intratumorally or via the hepatic artery. In AdrHIP-NIS-infected transformed hepatic cells, functional NIS was strongly expressed, as in cells infected with a cytomegalovirus-NIS vector. No NIS expression was found in AdrHIP-NIS-infected normal hepatocytes or transformed nonhepatic cells. In rats bearing multinodular HCC, AdrHIP-NIS triggered functional NIS expression that was preferential in tumor hepatocytes. Administration of 18 mCi of (131)I resulted in the destruction of AdrHIP-NIS-injected nodules. This study has identified the rHIP regulatory sequence as a potent liver tumor-specific promoter for the transfer of therapeutic genes, and AdrHIP-NIS-mediated (131)I therapy as a valuable option for the treatment of multinodular HCC.

Iodide Transporter NIS Regulates Cancer Cell Motility and Invasiveness by Interacting with the Rho Guanine Nucleotide Exchange Factor LARG

A number of solute carrier (SLC) proteins are subject to changes in expression and activity during carcinogenesis. Whether these changes play a role in carcinogenesis is unclear, except for some nutrients and ion carriers whose deregulation ensures the necessary reprogramming of energy metabolism in cancer cells. In this study, we investigated the functional role in tumor progression of the sodium/iodide symporter (NIS; aka SLC5A5), which is upregulated and mislocalized in many human carcinomas. Notably, we found that NIS enhanced cell migration and invasion without ion transport being involved. These functions were mediated by NIS binding to leukemia-associated RhoA guanine exchange factor, a Rho guanine exchange factor that activates the small GTPase RhoA. Sequestering NIS in intracellular organelles or impairing its targeting to the cell surface (as observed in many cancers) led to a further increase in cell motility and invasiveness. In sum, our results established NIS as a carrier protein that interacts with a major cell signaling hub to facilitate tumor cell locomotion and invasion.

41 THE SODIUM IODIDE SYMPORTER ENHANCES CELL MIGRATION AND INVASION

40 EBP50, A PDZ-CONTAINING PROTEIN, REGULATES EGFR-INDUCED CELL SCATTERING AND MIGRATION IN HUMAN CANCER BILIARY EPITHELIAL CELLS A. Claperon, M. Mergey, N. Guedj, B. de Singly, Y. Chretien, V. Paradis, C. Housset, L. Fouassier. INSERM, UMRS_938, CdR Saint-Antoine, UPMC Univ Paris 06, Paris, Service d’Anatomie Pathologique Hopital Beaujon, Clichy, INSERM, UMRS_U773, CdR Biomedicale Bichat, Paris, France E-mail: audrey.claperon@inserm.fr