Mass spectrometry analysis revealed that streptonigrin binds to the N-terminus of TGase 2 (amino acids 95⁻116), which is associated with inhibition of TGase 2 activity in vitro and with p53 stabilization in RCC.
MDM2 expression, combined with increased p53 expression, is associated with reduced survival in several cancers, but is particularly of interest in renal cell carcinoma (RCC) where evidence suggests the presence of tissue-specific p53/MDM2 pathway defects.
None of the 14 cases examined by SSCP analysis revealed mutations of the p53 gene, indicating that other genes at 17(p) might be important in the progression of this sub-type of RCC.
Our findings indicate that the elevated expression of progerin in RCCs results from the loss of pVHL and leads to p53 inactivation through p14/ARF suppression.
Our results suggest that the elevated p53 content in human renal cell carcinomas does not result from gene mutation and the p53 gene alterations are probably not an important mechanism in the development of human renal cell carcinomas.
Patients diagnosed with RCC in our center were into this study. mRNA expressions of p53 isoforms (p53α, p53β, p53γ) in tumors were determined by RT-PCR and real-time PCR.
Quantification of tumors cells with TP53 gene alterations showed a significant increase in the metastases compared to the primary RCCs, and, strikingly, the xenografts were similar to the metastases and not to the primary RCCs from which they were derived.Using laser-microdissection of p53-expressing tumor cells, we identified TP53-mutated tumor cells in the xenografts derived from the primary RCC, and in a lung metastasis later developed in one patient.
Recently, we found that the increase of TGase 2 expression is required for p53 depletion in RCC by transporting the TGase 2 (1-139 a.a)-p53 complex to the autophagosome, through TGase 2 (472-687 a.a) binding p62.
Recurrent secondary molecular alterations in clear cell RCC (BAP1, SETD2, PBRM1, and TP53) and papillary RCC (CDKN2A) may be associated with poor prognosis; however, intratumoral genomic heterogeneity may limit the clinical utility of these molecular biomarkers in renal mass biopsies.
Remarkably, cells of normal kidney epithelium also caused partial p53 repression in cell fusion experiments, suggesting that RCC-specific p53 repression may be based on an unknown dominant mechanism also acting in normal kidney tissue.
Spearman ranking correlation analysis showed that expression of PUMA, MCL-1, and p53 in was negatively correlated with RCC (r = -0.504, P = 0.001; r = -0.413, P = 0.008).
Statistical analysis revealed a close relationship between p53 protein expression and the tumor grade, as well as a significant association of HER-2 protein expression and gene amplification with the tumor stage of RCC.