EXPRESSION OF VON HIPPEL LINDAU GENE AS EXPOSURE AND OUTCOME MARKER FOR PCB/PCDF EXPOSED POPULATION

Abstract

ISEE-159 Purpose: Polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are ubiquitous environmental pollutants with multiple human and wildlife health effects. The effects of these chemicals on gene expression profiles in human peripheral lymphocytes have not been documented. We used cDNA microarray approach to study a group of people highly exposed to PCBs/PCDFs to identify gene expression as biomarkers in the peripheral lymphocytes. Methods: In 1979, a mass poisoning of more than 2000 people occurred in central Taiwan due to consumption of rice–bran cooking oil contaminated with PCBs and PCDFs. The exposed people, later called Yucheng (“oil-disease” in Chinese) victims, suffered from fatigue, chloracne and other skin manifestations, peripheral neuropathies, liver function abnormalities, and other signs and symptoms. The exposed people had high serum levels of PCBs and PCDFs 20 years after exposure. In 2002, peripheral blood of Yucheng men and unexposed controls were collected by venopuncture. The mRNAs extracted from lymphocytes were reversely transcribed into cDNAs and labeled with biotin, then hybridized to the cDNAs on the biochip. After the hybridization, the chips were applied to high resolution scanner for image analysis. We used the Millennium cDNA nylon membrance microarray chips, with 972 human cDNA, especially those involved in the pathways related to carcinogenesis and signal transduction, prepared by the Center of Microarray of National Cheng Kung Medical College. Fourteen endogenous human housekeeping genes (such as G3PDH, beta-actin, HPR1, etc.) were used as comparison. The expression was further confirmed by real time-polymerase chain reaction (PCR) by LightCycler (Roche Co.) in combination with the dsDNA binding dye SYBR Green I. Serially diluted PCR product of known concentration was used to construct a standard curve for quantification. Results: A total of 53 exposed and 35 control men participated in this study, with age 42 years. Among the exposed men, 42 had ever had serum levels of PCBs measured in 1980–1982, which averaged 81 ppb. The von Hippel Lindau (VHL) gene expressions were found to be increased with older age, and suppressed in exposed population as screened by microarray study, and confirmed by real time-PCR. Among exposed subjects, VHL gene expression was negatively associated with higher levels of PCBs measured in 1980–1982, and was reduced in those with chloracne, abnormal nails, or skin allergies, the most important manifestations associated with Yucheng. Conclusion: The VHL gene expression in peripheral lymphocytes may be exposure and outcome biomarkers for PCBs/PCDFs exposure.