Mutational analysis ofRashotspots in patients with urothelial carcinoma of the bladder

Abstract

BACKGROUND Mutational activation of Ras genes is established as a prognostic factor for the genesis of a constitutively active RAS-mitogen activated protein kinase pathway that leads to cancer. Heterogeneity among the distribution of the most frequent mutations in Ras isoforms is reported in different patient populations with urothelial carcinoma of the bladder (UCB). AIM To determine the presence/absence of mutations in Ras isoforms in patients with UCB in order to predict disease outcome. METHODS This study was performed to determine the mutational spectrum at the hotspot regions of H-Ras , K-Ras and N-Ras genes by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing followed by their clinical impact (if any) by examining the relationship of mutational spectrum with clinical histopathological variables in 87 UCB patients. RESULTS None of the 87 UCB patients showed point mutations in codon 12 of H-Ras gene; codon 61 of N-Ras gene and codons 12, 13 of K-Ras gene by PCR-RFLP. Direct DNA sequencing of tumor and normal control bladder mucosal specimens followed by Blastn alignment with the reference wild-type sequences failed to identify even one nucleotide difference in the coding exons 1 and 2 of H-Ras , N-Ras and K-Ras genes in the tumor and control bladder mucosal specimens. CONCLUSION Our findings on the lack of mutations in H-Ras , K-Ras and N-Ras genes could be explained on the basis of different etiological mechanisms involved in tumor development/progression, inherent genetic susceptibility, tissue specificity or alternative Ras dysfunction such as gene amplification and/or overexpression in a given cohort of patients.

Bladder cancer

“…17,21,22 Approximately 70% of cases are NMIBC. 17,21,22 The procedure may also include Bladder cancer risk factors [5][6][7][8][9]…”

“…On rare occasions, patients may have a congenital predisposition to bladder cancer 5,6. Glutathione S-transferase (GST) and N-acetyltransferase (NAT) are genes that make it difficult for a patient to detoxify urothelial carcinogens 5-7. Individuals possessing GST and NAT are at an increased risk for bladder cancer, which are potentiated by other risk factors, such as nicotine consumption.…”

The biological impacts of CEBPD on urothelial carcinoma development and progression

“…Furthermore, two divergent carcinogenic pathways (i.e., the papillary and the nonpapillary pathways) are used to explain the evolution of UBUC. The papillary pathway is driven by point mutations in FGFR3, RAS, and PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha) to develop hyperplasia, low-grade Ta, and highgrade Ta/T1 through constitutive activation of RTK/RAS/RAF/ mitogen-activated protein kinase (MAPK) and phosphoinositide 3kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathways related to cell proliferation (21,22). Instead, the nonpapillary pathway is defined by the loss-of-function mutation in genes associated with DNA replication/repair machinery such as p53 and RB that gives rise to the progression of dysplasia, Tis to MIBC (23).…”

Expression and Clinical Significance of SATB1 Gene in Urothelial Carcinoma of Bladder

“…All patients have not received preoperative chemotherapy or radiation therapy [18]. Bladder cancer samples were put into a refrigerator at -80℃ for RT-PCR detection [19][20].…”