Analysis of human tumors and human malignant cell lines for BK virus-specific DNA sequences

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Abstract
Most humans in the USA have been infected with BK virus (BKV), a human papovavirus. Because BKV has oncogenic properties, whether it may be a cause of human cancer was investigated. DNA from human tumors and malignant cell lines was assayed by molecular hybridization for BKV DNA, using BKV [32P]DNA as probe. The BKV [32P]DNA was labeled in vitro (nick translation) to specific activities of 1-2 .times. 108 cpm/.mu.g. The BKV DNA used to prepare the probes had the properties expected of authentic BKV genomes, including density of superhelical DNA, sedimentation velocity in alkaline and neutral sucrose gradients, production of 1 fragment by endonuclease EcoRI cleavage and 4 fragments by endonuclease Hin II + III cleavage and reassociation properties. BKV probes hybridized well and represented bona fide BKV DNA. Three different BKV [32P]DNA probes, i.e., from 3 distinct plaque isolates, were used to analyze DNA from BKV-transformed cells, normal human tissues and a large number of human tumors. All human DNA (cell lines, normal tissues, tumors) hybridized 5% with BKV DNA. Hybridization analysis of BKV-transformed hamster cell DNA indicated 5-6 copies of at least 88% of the BKV genome per cell. No BKV DNA sequences were detected (above the normal 5% hybridization to all human DNA) in the following normal human tissues: 10 kidney (BKV is usually isolated from urine), 3 spleen, 13 lung, 23 colon, 2 rectum, 1 ileum and 1 skin. No BKV-specific DNA was found in 166 tumors, including 5 carcinomas (Ca) of stomach, 3 Ca small intestine, 26 Ca colon, 9 Ca rectum, 31 Ca lung, 9 adenocarcinomas and 5 oat cell Ca of lung, 17 melanomas, 5 Ca prostate, 4 Ca bladder, 6 Wilms tumors, 4 hypernephromas, 15 Ca kidney, 7 brain tumors, 5 Hodgkin lymphomas, 10 lymphomas (immunosuppressed patients have a high incidence of lymphomas), 2 reticulum cell sarcomas (spleen), and 3 skin tumors. Also analyzed were 7 human malignant cell lines (melanoma, lung, rhabdomyosarcoma and glioblastomas), including several clones of a lung melanoma line; no BKV DNA sequences were detected. Because the probes could detect 1 copy of BKV DNA if only 10% of the cells were tumor cells, the results are very strong evidence that the tumors analyzed did not have a BKV etiology. The tumors tested represent about 50% of all cancers in the USA; there is no evidence that BKV is involved in the etiology of these types of tumors.