| Primary renal cell carcinoma(RCC) is one of the most common malignant tumor in urological neoplasms. Just like other tumors, the development of RCC is a complex process involving many genes and factors. Protein tyrosine phosphorylation, which plays a pivotal role in the regulation of cellular activities such as growth, differentiation, gene transcription and cell motility, is regulated by the balance between protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Disregulation in the activity of either of these players can lead to cellular transformation. Many protein tyrosine kinases are encoded by proto oncogenes and some protein phosphatases, such as PTEN, act as tumor suppressors. PTP BAS is a cytoplasmic PTP that has been originally cloned from a human basophilic leukaemia cell line by Maekawa and his colleagues in 1994. PTP BAS is expressed in various human tissues, especially in the kidney, lung and fetal brain at high levels. The apoptosis inducing membrane protein, Fas/CD95, was found to associate with Fas associated phosphatase 1(FAP 1) which is identical with PTP BAS. PTP BAS has been studied on the various malignancies such as colonal carcinoma, pancreas carcinoma, stomach carcinoma, T cell leukaemia, ovary carcinoma, liver carcinoma, breast carcinoma, lung carcinoma and some other sarcomas, but not the RCC, even though over expression of PTP BAS was reported in renal tissue. Our study was to investigate whether the expression of the PTP BAS in RCC tissues detected by Northern blot was associated with the development and the progress of the RCC on the level of mRNA. Our results showed that the level of PTP BAS mRNA expressed in the 31 RCC tissues was significantly lower than that intheir adjacent normal renal tissues(p <0.01), and the expression rate of the 9.5 kb transcripts in RCCs and their adjacent normal renal tissues was 74.2%(23/31) and 93.5%%(29/31), respectively. It was also found that there was no or low expression in the 293 cell strain and the RCC cell stains (786 O,A498). Statistically, we found no relationship between the expression level of 9.5kb transcripts and the patients' age, gender, localization of the carcinoma, side of the lesion, volume, tumor stage and pathological type of RCC(p>0.05).Occasionally we noticed a common phenomenon that the isolated RNA in the adjacent normal renal tissues tended to degrade than that in the carcinoma tissues during the process of isolating the total RNA from the tissues. To confirm this finding and to investigate the relationship between the RNA degradation and the development and the progress of the RCC, we measured the ratios of 28s to 18s of the total RNA isolated from the 30 pairs of RCC and their adjacent tissues obtained at the same time of post nephrotectomy. As a result, we found that: (1) the ratios of 28s to 18s of the total RNA isolated from RCC were significantly higher than those from their adjacent tissues(p <0.05). (2) In the same patient's specimen, the ratios decreased in a time related fashion after nephrotectomy, and the ratios of RCC's RNA were much higher than those of their adjacent tissues' RNA(p <0.01). (3)The ratios of the RCC tissues' RNA were nearly 1 at 40 min after clamping of the artery while the ratios of the adjacent tissues' RNA were nearly 1 at 90 min after clamping of the artery. (4)Theβ actin mRNA of 16 RCCs was much higher than that of their accordingly adjacent tissues by Northern blotting with 28S RNA as internal control. This confirmed that the RNA from the adjacent tissues of RCCs was apt to decay than that from RCC tissues.To clarify the underlying cause, we evaluated the expression of the RNase 1 in both RCC and their adjacent tissues by the EnvisionTM technique. The results showed that the expression of RNase 1 in the renal tubular cells was much higher than that in RCC cells and the RNase 1 was also detected in the renal tubular lumen. We also found that the expression of the RNase 1 in RCC had relationship with the the pathological type, but not the patient...
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