Radiation-induced killing and neoplastic transformation of human cells: influence of oncogenes, tumor suppressor genes, cytokines and chemotherapeutic agents.
President, Radiation Research Society, 2000-2001
Radiation Chemistry, The Ohio State University.
A major aspect of Dr. Redpath's research is the study of quantitative and mechanistic aspects of mechanisms of radiation-induced neoplastic transformation of cells in vitro. His laboratory has developed the only quantitative assay for radiation-induced neoplastic transformation which uses human-derived cells (HeLa x skin fibroblast human hybrid cells). The assay has been applied to a variety of pragmatic studies including pH effects, cell density effects and radiation dose-fractionation and dose-rate studies. Current research in his laboratory is focused on understanding the risk of cancer induction by low doses of ionizing radiation, particularly those used in the practice of diagnostic radiology and those experienced by workers in the nuclear industry. Such investigation has potentially important societal implications. Current dogma applied by regulatory bodies assumes that the risk of radiation-induced cancer is linear with radiation dose. Such an assumption has the implication that no dose of radiation is safe. Research in Dr. Redpath's laboratory, as well as those of others around the world, have strongly challenged this dogma. Results for the endpoint of neoplastic transformation in vitro indicate that the dose-response curve is J-shaped. This implies that there is a threshold dose below which no cancer is induced and where the radiation may prevent cancer formation. This threshold dose is of the order of 10cGy, i.e. above the largest doses typically experienced in diagnostic radiology.
E. Elmore, X.Y. Lao, R. Kapadia, M. Swete and J.L. Redpath, Neoplastic transformation in vitro by mixed beams of high-energy iron ions and protons. Radiat. Res. 2011, in press
E. Elmore, X.Y. Lao, R. Kapadia and J.L. Redpath, Efect of dose-rate on induction of neoplastic transformation in vitro by low doses of 232 MeV protons. Int. J. Radiat. Biol. 87, 622-627 (2011).
E. Elmore, X-Y. Lao, R. Kapadia, and J.L. Redpath, " Threshold-type dose response for induction of neoplastic transformation by 1 GeV/nucleon iron ions". Radiat. Res. 171, 764-770 (2009).
R.E.J Mitchel and J.L. Redpath, "Comment on'Mammography:oncogenicity at low doses'". J. Radiol. Prot. 29, 457-459 (2009).
E. Elmore, X-Y. Lao, R. Kapadia, E. Giedinski, C. Limoli and J.L. Redpath, "Low doses of very low dose-rate low-LET radiation suppress radiation-induced neoplastic transformation in vitro and induce an adaptive response". Radiat. Res. 169, 311-318 (2008).
J.L. Redpath and E. Elmore, "Radiation-induced neoplastic transformation, hormesis and risk assessment." Dose Response 5, 123-130 (2007).
M. Ko, X-Y. Lao. R. Kapadia, E. Elmore and J.L. Redpath, "Neoplastic transformation in vitro by low doses of ionizing radiation: Role of adaptive response and bystander effects." Mutat. Res. 597, 11-17 (2006).
J.L. Redpath, "Health risks of low photon energy imaging." Rad. Prot. Dosim. 122, 528-533 (2006).
E. Elmore, X-Y. Lao, R. Kapadia and J.L. Redpath, "The effect of dose-rate on neoplastic transformation in vitro by low doses of low-LET radiation." Radiat. Res. 166, 832-838 (2006).
S.J. Ko, X.Y. Lao, S. Molloi, E. Elmore and J.L. Redpath, Neoplastic transformation in vitro after exposure to low doses of mammographic energy X-rays: Quantitative and mechanistic aspects. Radiat. Res. 162, 646-654 (2004).
J.L. Redpath, "Radiation-induced neoplastic transformation in vitro: Evidence for a protective effect at low doses of low LET radiation". Cancer Metastasis and Reviews 23, 333-339 (2004).
J.L. Redpath, "Radiation-induced neoplastic transformation in vitro: Evidence for a protective effect at low doses of low LET radiation". Cancer and Metastasis Reviews 23, 333-339(2004).
J.L. Redpath, Q. Lu, X.Y. Lao, S.Y. Molloi, E. Elmore and J.L. Redpath, Low doses of diagnostic energy X-rays protect agianst neoplastic transformation in vitro. Int. J. Radiat. Biol. 79, 235-240 (2003).
J.L. Redpath, D. Liang, T.H. Taylor, C. Christie and E. Elmore, The shape of the dose-response curve for radiation-induced neoplastic transformation in vitro: Evidence for an adaptive response against neoplastic transformation by low doses of low-LET radiation. Radiat. Res. 156, 700-707 (2001).
J.L. Redpath and R.J. Antoniono, Induction of an adaptive response against low dose-gamma radiation. Radiat. Res. 149, 517-520 (1998).
M.S.Mendonca, RJ.Antoniono, and J.L.Redpath, "Delayed expression of heritable damage and epigenetics in the radiation-induced neoplastic transformation of human hybrid cells", Radiat.Res., 134, 209-216 (1993).
American Cancer Society Institutional Research Grant
Radiation Research Society
American Association for Cancer Research
UCI Chao Family Comprehensive Cancer Center