Gain of X chromosome associated with development of precancerous liver lesion and with progression to hepatocellular carcinoma
Authors: Anchalee Tantiwetrueangdet, Ravat Panvichian, Supaporn Waeteekul, Pattana Sornmayura, Koset Pinpradap, Sophon Jirasiritham, Surasak Leelaudonlipi, Ekapop Sirachainun, Umaporn Udomsubpayakul, Wutthi Sumetchotimaytha, Teeravut Kuhapraema
Journal: Cancer Research (2006)

Proc Amer Assoc Cancer Res, Volume 47, 2006

4201 

The molecular carcinogenesis of hepatocellular carcinoma (HCC) is largely unclear, although the major causative agents for HCC, hepatitis B virus (HBV), hepatitis C virus (HCV) and aflatoxin (AFB), are well defined. Since the majority of HCC are associated with a background of chronic liver disease, the carcinogenesis of HCC is considered to be a long-term, multi-step process that involves progression from precancerous lesion to cancerous lesion caused by multiple genetic alterations. In our previous study, using comparative genomic hybridization (CGH) to metaphase chromosomes, we compared the genomic aberrations of primary human hepatocellular carcinoma tissues with those of matched non-cancerous liver tissues. Interestingly, we found that the most frequently detected gain of DNA copy numbers in HCC tissues involved chromosome X (62.5 %), 1q (38.9%), and 8q (22%). In contrast, the gain of DNA copy numbers in the matched non-cancerous liver tissues involved only chromosome X (66%). Our CGH results suggest that gain of X chromosome is implicated in the development of HCC. The objective of current study was to validate the association of gain of X chromosome in HCC and its precancerous lesion by using fluorescence in situ hybridization (FISH) technique to count the number of chromosome X copies in interphase nuclei of HCC and its precancerous lesion with centromere-specific probe for chromosome X. This study included 26 HCC patients who underwent surgical tumor removal with the patients consent. Therefore, there were 26 pairs of HCC and the matched non-cancerous liver specimens: 14 pairs of HCC and non-cirrhotic liver specimens, and 12 pairs of HCC and cirrhotic liver specimens. In each liver specimen, three sequential 10-μm sections were cut from paraffin-embedded liver tissue block. One section was stained with hematoxylin and eosin (H&E) for pathologists to examine the pathology of liver specimen. Another two sections were prepared for the isolation of individual nuclei. FISH was performed on the isolated nuclei with centromere-specific probes for chromosome X, and Y (Vysis Inc). At least 100 isolated nuclei were counted and normal hepatocyte nuclei were counted as reference control. The frequency of gain of X chromosome in the isolated nuclei was the following: 92.3% (24/26) for HCC, 58.3% (7/12) for cirrhotic, and 35.7% (5/14) for non-cirrhotic liver tissues. These findings demonstrate the association of increased copy number of X chromosome in HCC and its precancerous lesion. The high frequency of gain of X chromosome, as shown in our CGH and FISH experiments, suggests the crucial role of chromosome X during the development of precancerous liver lesion and the progression to hepatocellular carcinoma. (Supported by Research Grant of Ramathibodi Hospital, Mahidol University)