Characterization and Analysis of Oncofetal tRNA and Its Possible Application for Cancer Diagnosis and Therapy

Abstract

In 1966 Borek and his co-workers reported that tumor cells have higher levels of tRNA-methylase activity than normal cells, and consequently tRNA from tumor cells is hypermodified (Tsutsui et al. 1966). They proposed that such hypermodified tRNA has a specific functional role in tumor cells (Tsutsui et al. 1966). Although the validity of their findings was brought into question from time to time by reports of contradictory results, their fascinating hypothesis stimulated much work in this field. During the past 15 years an enormous number of reports of the appearance of new isoacceptor tRNA species in tumor cells have been published (Nishimura 1979a, b). However, it should be mentioned that in most cases those reports are suggestive but not quite informative, since new isoaccepting tRNA species were only detected by changes in the chromatographic profile of particular amino-aeyl-tRNAs in column chromatography, such as RPC-5 or benzoylated DEAE cellulose, and therefore it is not known whether those new isoaccepting tRNA species are derived by transcription of different tRNA gerie(s) or by changes in post-transcriptional modification. It was difficult to obtain enough pure tRNA from tumor cells for structural study using conventional sequencing methods.