[Quantitative analysis of p53 and related genes mRNA in rat hepatocarcinogenesis induced by 3'-Me-DAB].

BACKGROUND & OBJECTIVE: p53 gene mutations and abnormal expression of p53 in hepatocarcinoma have been reported, but alteration in mRNA level is not yet understood. In order to find out the alteration in mRNA levels of p53, glutathione S-transferase P (GST-P), alpha-fetoprotein (AFP), and albumin in genesis, developing, and prognosis of hepatocarcinoma, quantitative analysis of mRNA levels of p53, GST-P, AFP, and albumin in prehepatocarcinoma and hepatocarcinoma foci was performed.

METHODS

During hepatocarcinogenesis of F344 rat induced by 3'-methyl-4-dimethylamino-azobenzene (3'-Me-DAB), the levels of these mRNAs were quantitatively analyzed by LightCycler V3 System real-time RT-PCR after capturing accurately micro-foci in prehepatocarcinoma and hepato-carcinoma of rats with laser capture microdissection (LCM).

RESULTS

At the 6th, 12th and 24th experiment weeks, the p53 mRNA levels in all of prehepatocarcinoma foci were markedly higher than those in the adjacent normal tissues (all of P < or = 0.001), and gradually decreased from the 6th week to the 24th week (P < 0.01). The content of p53 mRNA in hepatocarcinoma foci was higher than that in normal tissue (P = 0.028 and 0.013), but lower than that in prehepatocarcinoma foci. At 24th weeks, the sections of livers exhibited intensive immunostaining of p53 protein in prehepatocarcinoma and hepatocarcinoma foci. At any time-point of experiment, GST-P mRNA levels in prehepatocarcinoma foci were significantly higher than those in the adjacent normal liver tissue and hepatocarcinoma foci (all of P < 0.001). The concentration of AFP mRNA was the highest (P < 0.001) and that of albumin mRNA was the lowest (P < 0.01) in hepatocarcinoma foci as compared with adjacent normal tissue and prehepatocarcinoma foci. The GST-P protein and AFP protein were expressed strongly in prehepatocarcinoma and hepatocarcinoma foci, respectively.

CONCLUSION

GST-P and AFP mRNA overexpressed in prehepatocarcinoma and hepatocarcinoma foci respectively will be profitable markers for diagnosis during hepatocarcinogenesis. The p53 mRNA highly expressed at early stage of prehepatocarcinoma and hepatocarcinoma, but the increasing concentration of p53 protein was found at later stage.