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Mitrofanova
Rat sodium iodide symporter allows using lower dose of 131I for cancer therapy.Mitrofanova E, Unfer R, Vahanian N, Link C. Gene Ther. 2006 Jul;13(13):1052-6. Epub 2006 Mar 9. [abstract only]
"Efficient gene delivery is a critical obstacle for gene therapy that must be overcome. Until current limits of gene delivery technology are solved, identification of systems with bystander effects is highly desirable. As an anticancer agent, radioactive iodine (131)I has minimal toxicity. The physical characteristics of (131)I decay allow radiation penetration within a local area causing bystander killing of adjacent cells. Accumulation of (131)I mediated by the sodium iodide symporter (NIS) provides a highly effective treatment for well-differentiated thyroid carcinoma. Other types of cancer could also be treated by NIS-mediated concentration of lethal (131)I radiation in tumor cells. Our group and others previously reported that a significant antitumor effect in mice was achieved after adenoviral delivery of rat or human NIS gene following administration of 3 mCi of (131)I. We have also demonstrated 5-6-fold greater uptake of (125)I by rat NIS over human NIS in human cancer cells. Recently, we reported the capability of the rat NIS and (131)I to effectively induce growth arrest of relatively large tumors (approximately 800 mm(3)) in an animal model. In the present work tumor growth inhibition was achieved using adenoviral delivery of the rat NIS gene and 1 mCi of (131)I (one-third of the dose used in earlier reports). We also demonstrated that a higher concentration of (123)I was accumulated in the NIS-expressing tumors than in the thyroid 20 min after radioiodine administration. The highest intratumoral radioiodine concentration was observed along the needle track; however, the rat NIS-(131)I effectively induced growth arrest of tumor xenografts in mice through its radiological bystander effect. Importantly, the rat NIS allowed reducing the injected radioiodine dose by 70% with the same antitumor efficacy in pre-established tumors. These results suggest that the rat NIS gene may be advantageous compared to the human gene in its ability to enhance intratumoral (131)I uptake."
Effective growth arrest of human colon cancer in mice, using rat sodium iodide symporter and radioiodine therapy.Mitrofanova E, Unfer R, Vahanian N, Kane S, Carvour M, Link C. Hum Gene Ther. 2005 Nov;16(11):1333-7. [abstract only]
"We have demonstrated that the rat sodium iodide symporter (rNIS) and 131I can effectively induce growth arrest of human prostate tumor xenografts [Mitrofanova, E., Unfer, R., Vahanian, N., Daniels, W., Roberson, E., Seregina, T., Seth, P., and Link, C. (2004). Rat sodium iodide symporter (rNIS) for radioiodide therapy of cancer. Clin. Cancer Res. 10, 6969-6976]. In that study the average size of tumors established in athymic nude mice was 200 +/- 50 mm3 when treated. Testing under more rigorous and extreme in vitro conditions will better evaluate the ability of an anticancer approach to induce tumor regression or killing capacity in preclinical studies. In this work the ability of the rNIS and 131I system to inhibit the growth of relatively large (about 800 mm3 when treated with 131I) and rapidly growing colon tumors in an animal model was examined. in vitro experiments demonstrated that transduction of human colon cancer cells with Ad-rNIS resulted in a 100- to 150-fold increase in 125I uptake compared with nontransduced cells. Western blot analysis revealed robust expression of rNIS protein in cells 72-120 hr posttransduction with Ad-rNIS. Immunocytochemical analysis demonstrated that intracellular localization of rNIS-specific staining was observed mainly in plasma membranes of cells. in vitro studies revealed an immediate inhibition of growth of rapidly expanding tumors after radioiodine injection in the rNIS and 131I treatment group of mice. Twenty-seven percent of experimental mice survived more than 30 days (p = 0.019), whereas control groups had only 7% survival over 30 days. This is the first report demonstrating that rat NIS and 131I can effectively induce growth arrest of relatively large tumors in an animal model."
Rat sodium iodide symporter for radioiodide therapy of cancer.Mitrofanova E, Unfer R, Vahanian N, Daniels W, Roberson E, Seregina T, Seth P, Link C Jr. Clin Cancer Res. 2004 Oct 15;10(20):6969-76.
"Design and development of new approaches for targeted radiotherapy of cancer and improvement of therapeutic index by more local radiation therapy are very important issues. Adenovirus-mediated delivery of the sodium iodide symporter (NIS) gene to cancer cells is a powerful technique to concentrate lethal radiation in tumor cells and eradicate tumors with increased therapeutic index. A replication-defective adenoviral vector expressing the rat NIS gene (Ad-rNIS) was used for in vitro gene delivery and into human prostate cancer xenografts to study antitumor effect. Robust function of the rat symporter was detected in DU145, T47D, and HCT-15 human cancer cell lines transduced with Ad-rNIS. All three cancer cell lines successfully transferred functionally active rat symporter to the plasma membrane, resulting in very high levels of iodine-125 accumulation. Three-dimensional multicellular tumor spheroids derived from DU145 human prostate cancer cells were transduced with Ad-rNIS and incubated with (131)I for 24 hours. After treatment, spheroids rapidly decreased in size and disappeared within 10 days. In vivo data revealed an inhibition of tumor growth in athymic nude mice after intratumoral Ad-rNIS injection followed by (131)I administration. Eighty-eight percent of experimental mice survived >30 days, whereas control groups had only 18% survival >30 days. This is the first report that demonstrates the rat NIS gene can effectively induce growth arrest of human tumor xenografts after in vivo adenoviral gene delivery and (131)I administration. The data confirm our hypothesis that the rat NIS gene is an attractive suicide gene candidate for cancer treatment."
Sodium iodide symporter/radioactive iodine system has more efficient antitumor effect in three-dimensional spheroids.Mitrofanova E, Hagan C, Qi J, Seregina T, Link C Jr. Anticancer Res. 2003 May-Jun;23(3B):2397-404. [abstract only]
"The sodium iodide symporter (NIS) is a plasma membrane protein that mediates active uptake of inorganic iodide from plasma into thyroid cells. Expression of the NIS gene in tumor cells may provide a novel mechanism for treating cancer. Previously, we cloned cDNA of rat NIS into the retroviral vector LXSN, transduced human and murine tumor cells, and demonstrated 50-60% killing effect of 131I in cells expressing NIS. However, monolayer cultures of cancer cells cannot adequately represent some aspects of the growth and microenvironmental conditions of three-dimensional (3D) solid tumors. On the other hand, animal models are time consuming and costly and not always reasonable for the first estimation of scientific approaches. An in vitro model of multicellular tumor spheroids growing as a 3D-structure provides an important link between monolayer cell cultures and animal experiments. This model is especially crucial for suicide systems utilizing radioisotopes as the killing agent because the deposition of radiation energy causes DNA damage in cells more effectively in 3D-structure. In this study we used a retroviral vector for introduction of the rat NIS gene into DU145 prostate cancer cells. The liquid-overlay technique was exploited to create a tumor spheroid model. We established that uptake of 125I in monolayer culture cells containing the NIS was 40- to 50-fold greater than in DU145 cells without NIS. Using a clonogenic assay for monolayer culture, we demonstrated a 50-70% killing effect of 131I on DU145 cells expressing the NIS gene. The same dose of 131I resulted in complete death of tumor spheroids composed of the DU145-NIS cells. Our data demonstrates significant anti-tumor efficacy of novel radioisotope concentrator gene therapy in a multicellular spheroid model, thus proving to be a useful link between the in vitro system and in vivo animal model."
The rat sodium iodide symporter gene permits more effective radioisotope concentration than the human sodium iodide symporter gene in human and rodent cancer cells.Heltemes LM, Hagan CR, Mitrofanova EE, Panchal RG, Guo J, Link CJ. Cancer Gene Ther. 2003 Jan;10(1):14-22. [abstract only]
"Expression of the sodium iodide symporter (NIS) gene in tumor cells may provide a novel mechanism for treating cancer. The NIS mediates the normal physiological transport of iodide across the thyroid cell membrane. This mechanism of iodide uptake has been used to both diagnose and treat thyroid cancer. Tissue expression of the NIS is largely limited to the thyroid; therefore, expression of the NIS gene in cancer cells would allow for specific iodine uptake, radioisotope accumulation, and treatment. In this study, we directly compared the human and rat NIS (rNIS) for their ability to concentrate radioisotope into human and rodent cancer cells. Perchlorate-sensitive (125)I uptake in multiple cell lines was demonstrated following transduction with retroviral vectors expressing either the human or rNIS gene. Surprisingly, iodine uptake was consistently higher with the rNIS gene, up to 5-fold greater, when compared to the human gene, even within a variety of human tumor cell lines. This iodine uptake allowed for cell killing following (131)I treatment in NIS-transduced cells when assayed by in vitro clonogenic assays. These results demonstrate that the rNIS gene provides superior iodine uptake ability, and may be preferable for use in designing anticancer gene therapy approaches."
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