Mutation of the p53 tumor suppressor gene in transitional cell carcinoma of the urinary tract in Taiwan

High expression of TMEM40 is associated with the malignant behavior and tumorigenesis in bladder cancer

BACKGROUND

Bladder cancer (BCa) is one of the most common cancers in the urinary system among the world. Previous studies suggested that TMEM40 expression level was significantly associated with clinicopathological parameters including histological grade, clinical stage and pT status of bladder cancer. However, the molecular mechanism of TMEM40 in BCa remains poorly understood.

METHODS

Real-time quantitative RT-PCR (qRT-PCR) and western blot (WB) were used to examine the expression levels of TMEM40 in BCa tissues, paired non-cancer tissues and cell lines. A series of experiments, including CCK-8, wound healing, flow cytometry, transwell and EdU assays were performed to assess the effects of TMEM40 on cell proliferation, cell cycle and apoptosis, migration and invasion. In addition, tumor growth was evaluated in vivo using a xenogenous subcutaneously implant model. All statistical analyses were executed by using the SPSS 20.0 software. All experimental data from three independent experiments were analyzed by Student's t test and results were expressed as mean ± standard deviation.

RESULTS

In this study, we identified the role of TMEM40 in the tumorigenesis of bladder cancer and found that it was upregulated in bladder cancer tissues and cell lines, compared with their normal counterparts. The results demonstrated that effective silence of TMEM40 expression suppressed cell proliferation, blocked G1-to-S cell cycle transition, and inhibited cell migration and invasion in human bladder 5637 and EJ cell lines. Consistently, in vivo data showed that TMEM40 silencing could dramatically decreased tumor growth. Further study revealed that TMEM40 knockdown resulted in accumulation of p53 and p21 protein and decrease of c-MYC and cyclin D1 protein.

CONCLUSION

These data suggest that TMEM40 represents a potential oncogene, which exert a crucial role in the proliferation and apoptosis via the p53 signaling pathway in BCa, thus probably serve as a novel candidate biomarker and a potential therapeutic target for patients with BCa.

Rb deficiency accelerates progression of carcinoma of the urinary bladder in vivo and in vitro through inhibiting autophagy and apoptosis

Urinary bladder cancer is known as a common cancer diagnosed across the world and results in significant mortality and morbidity rates among patients. The retinoblastoma (Rb) protein, as a main tumor suppressor, controls cellular responses to potentially oncogenic stimulation. Rb phosphorylation could disrupt E2F complex formation, resulting in diverse transcription factor dysfunction. In our study, we investigated how Rb is involved in controlling urinary bladder cancer progression. The results indicate that Rb expression is reduced in mice with urinary bladder tumor, and its suppression leads to urinary bladder cancer progression in vivo and in vitro. Rb mutation directly results in tumor size with lower survival rate in vivo. Rb knockdown in vitro promoted bladder tumor cell proliferation, migration and invasion. Interestingly, Rb knockout and knockdown result in autophagy and apoptosis inhibition via suppressing p53 and caspase-3 signaling pathways, enhancing bladder cancer development in vitro and in vivo. These findings reveal that Rb deficiency accelerated urinary bladder cancer progression, exposing an important role of Rb in suppressing urinary bladder cancer for treatment in the future.

Investigation of the association between mitochondrial DNA and p53 gene mutations in transitional cell carcinoma of the bladder

Bladder carcinoma is the most common malignancy of the urinary tract. The major aim of the present study is to investigate the association between mitochondrial DNA (mtDNA) and p53 gene mutations in bladder carcinoma. A total of 30 patients with transitional cell carcinoma and 27 controls were recruited for the study. Bladder cancer tissues were obtained by radical cystectomy or transurethral resection. Genomic DNA was extracted from peripheral blood. mtDNA and p53 genes were amplified by polymerase chain reaction and sequenced directly. A total of 37 polymorphisms were identified, among which, 2 mutations were significant in the patient group, and 1 mutation was significant in the control group. Additionally, 5 different moderate positive correlations between mtDNA mutations and 3 different positive correlations between p53 gene and mtDNA mutations were detected. The high incidence of mtDNA and p53 gene mutations in bladder cancer suggests that these genes could be important in carcinogenesis.

Concomitant bifocal urothelial carcinoma and breast tumor: second primary cancer or metastatic spread to the breast?

Metastases to the mammary gland are an uncommon event in the natural history of most malignant tumors. We report the case of a 60-year-old woman who presented initially with bifocal urothelial carcinoma with a single breast tumor, raising the issue of a primary cancer or a metastatic spread to the breast. The diagnosis of breast metastasis was aided by identity of pathology, immunochemistry, and molecular biology findings between the primary tumor and the breast lesion, among which are the p.K120M mutation, a very rare TP53 mutation, and HER2 overexpression with underlying polysomy of chromosome 17.

"P53 codon 72 single base substitution in viral hepatitis C and hepatocarcinoma incidences"

Viral infection with hepatitis C virus (HCV) has a high propensity in becoming chronic and it is the major cause of hepatocellular carcinoma (HCC) worldwide. This review was basically established to illustrate the putative role of the P53 gene Arg72Pro polymorphism on various cancer models and viral infections, focusing on HCV and HCC incidences. Authors studied the 72 G/C single base substitution of P53 gene at codon 72 using various polymorphic techniques. Intriguingly, authors investigated that the P53 codon 72 plays a crucial role as risk factor in several cancer models. Others found that there is no association between codon 72 genotypes and HCV disease severity or liver cancer. Moreover, the lack of a significant relationship between this polymorphism and risk of HCC shows that it does not predispose towards hepatocarcinogenesis and the frequent loss of the proline allele in HCV-associated carcinogenesis of the liver plays some critical role in hepatocarcinogenesis. Amazingly, there is a significant correlation between male homozygotes for P53 72Pro with HCV type 1b infection. However, there was no significant difference between the P53 polymorphism and HCV genotypes 2a and 2b. It was concluded that the P53 gene polymorphism at codon 72 has been investigated as potential risk factor in several cancer models and HCV infections.

Mutation Spectra of Kras and Tp53 in Urethral and Lung Neoplasms in B6C3F1 Mice Treated with 3,3′,4,4′-Tetrachloroazobenzene

3,3′,4,4′-tetrachloroazobenzene (TCAB) is a contaminant formed during manufacture of various herbicide compounds. A recent National Toxicology Program study showed B6C3F1 mice exposed to TCAB developed a treatment-related increase in lung carcinomas in the high-dose group, and urethral carcinomas, an extremely rare lesion in rodents, in all dose groups. As the potential for environmental exposure to TCAB is widespread, and the mechanisms of urethral carcinogenesis are unknown, TCAB-induced urethral and pulmonary tumors were evaluated for alterations in critical human cancer genes, Kras and Tp53. Uroplakin III, CK20, and CK7 immunohistochemistry was performed to confirm the urothelial origin of urethral tumors. TCAB-induced urethral carcinomas harbored transforming point mutations in K-ras (38%) and Tp53 (63%), and 71% displayed nuclear TP53 expression, consistent with formation of mutant protein. Transition mutations accounted for 88% of Tp53 mutations in urethral carcinomas, suggesting that TCAB or its metabolites target guanine or cytosine bases and that these mutations are involved in urethral carcinogenesis. Pulmonary carcinomas in TCAB-exposed animals harbored similar rates of Tp53 (55%) and Kras (36%) mutations as urethral carcinomas, suggesting that TCAB may induce mutations at multiple sites by a common mechanism. In conclusion, TCAB is carcinogenic at multiple sites in male and female B6C3F1 mice through mechanisms involving Tp53 and Kras mutation.

p53 codon 72 polymorphism as a progression index for bladder cancer

The aim of this study was to calculate the positive predictive value (PPV) and negative predictive value (NPV) to determine whether p53 codon 72 can be used as a bladder cancer management index. Ninety-six patients diagnosed with bladed cancer and two control groups of 427 randomly sampled community participants and 142 non-cancerous individuals without a prior history of cancer were enrolled. After preliminary analysis, the convergent validity resulted in 96 patients from this study and 129 patients from our previous study. Results showed that these two groups were of the same population, and could be merged into one case group. Logistic regression showed that the Pro/Pro genotype was not statistically significantly associated with bladder cancer incidence using each sample set after adjustment by age and gender. Moreover, the Pro/Pro genotype was not associated with high-grade tumors (P=0.078), but was highly correlated to muscle-invasive tumors (P=0.002). Pro/Pro genotype carriers were estimated to have a 3.36-fold higher risk to develop invasive tumors compared to non-carriers. The NPV of the Pro/Pro genotype for invasive tumors was 88.00%, and the PPV was 31.91%. By Cox regression analysis, high-grade tumors were associated with recurrence (P=0.020, OR=1.83), whereas invasive tumors were associated with cancer-related death (P<0.001, OR=2.87). p53 codon 72 polymorphism is associated with bladder cancer progression rather than incidence and prognosis. The Pro/Pro genotype in p53 codon 72 polymorphism shows a high NPV for bladder cancer progression, thus, it can be used clinically as a progression index in bladder cancer management.

Polymorphisms of TP53 are markers of bladder cancer vulnerability and prognosis

OBJECTIVES

We have reported previously that the TP53 codon72 polymorphism (rs1042522) is associated with the incidence and invasiveness of bladder cancer in a Han Chinese population. Using an enlarged sample, we investigated the role of rs1042522 and of tagSNPs that were predicted to be in linkage disequilibrium with codon72 in relation to the incidence, invasiveness, and prognosis of bladder cancer.

METHODS AND MATERIALS

A sample of 201 patients and 311 controls without cancer were genotyped for 5 tagSNPs using tetra-primer ARMS and/or an allele-specific PCR technique.

RESULTS

The genotyped data were analyzed using Haploview 4.2, and a 10,000-permutation test showed that the rs9895829G allele (P = 0.003) and the rs1788227C allele (P = 0.027) were both associated with the incidence of bladder cancer. With respect to haplotype associations, after the data were adjusted for age, the haplotypes GTT (P = 0.001) and GGTC (P < 0.001) were correlated with a low incidence of bladder cancer. In contrast, none of the TP53 haplotypes were associated significantly with high tumor grade or muscle invasiveness. On the basis of Cox regression analysis, haplotype CGCC and invasiveness were associated with cancer-related death. Structural equation modeling showed that haplotypes GGCC and CGCC played opposing roles with respect to bladder cancer-related death; haplotype GGCC was a protective factor, whereas haplotype CGCC was a risk factor.

CONCLUSIONS

The TP53 codon72 polymorphism appears to play a crucial role in determining the association between TP53 haplotype and the incidence and prognosis of bladder cancer. Further functional assays to confirm whether these TP53 haplotypic variants interact with the proteins N-Myc and NDRG is necessary.

Association of DRD4 uVNTR and TP53 codon 72 polymorphisms with schizophrenia: a case-control study

Background

The tumour supressor gene TP53 is thought to be involved in neural apoptosis. The polymorphism at codon 72 in TP53 and the long form variants of the upstream variable number of tandem repeats (uVNTR) polymorphism in the dopamine D4 receptor (DRD4) gene are reported to confer susceptibility to schizophrenia.

Methods

We recruited 934 patients with schizophrenia and 433 healthy individuals, and genotyped the locus of the TP53 codon 72 and DRD4 uVNTR polymorphisms by combining the polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP) with direct sequencing.

Results

No significant differences were found in the frequency of the genotype of the TP53 codon72 polymorphism between patients with schizophrenia and their controls. However, the long form alleles (≥ 5 repeats) of the DRD4 uVNTR polymorphism were more frequent in patients with schizophrenia than in controls (p = 0.001). Hence, this class of alleles might be a risk factor for enhanced vulnerability to schizophrenia (odds ratio = 3.189, 95% confidence interval = 1.535-6.622). In the logistic regression analysis, the long form variants of the DRD4 polymorphism did predict schizophrenia after the contributions of the age and gender of the subjects were included (p = 0.036, OR = 2.319), but the CC and GG genotypes of the codon 72 polymorphism of TP53 did not.

Conclusions

The long form variants of the uVNTR polymorphism in DRD4 were associated with schizophrenia, in a manner that was independent of the TP53 codon 72 polymorphism. In addition, given that the genetic effect of the TP53 codon 72 polymorphism on the risk of developing schizophrenia was very small, this polymorphism is unlikely to be associated with schizophrenia. The roles that other single nucleotide polymorphisms (SNPs) in the TP53 gene or in other apoptosis-related genes play in the synaptic dysfunction involved in the pathogenesis of schizophrenia should be investigated.

Mutations in Exons 6 and 7 of TP53 Gene Correlate Positively with Serum Tumor Necrosis Factor Alpha Independent of Microsatellite Instability in BAT26 Gene in Egyptian Patients with Endometrial Carcinoma

Abnormalities in the TP53 gene are the most frequent genetic alterations in human cancers. The role and mechanism of TP53 mutations have been well studied in many types of human cancer. Similarly, the presence of microsatellite instability (MSI) in the DNA mismatch repair system (hMSH2) may provide evidence of faulty DNA mismatch repair. One of the most important locations of MSI is the BAT26 gene. In addition, deranged serum cytokines, especially elevated levels of the tumor necrosis factor (TNF) alpha, have been found in many gynecological conditions.

Aims

The current study aimed at evaluating mutations in exons 6 and 7 of TP53 and the presence of microsatellite instability in BAT26 of the hMSH2 system in Egyptian patients with endometrial carcinoma. The study also evaluated whether there was a correlation between any of these genetic mutations/instability and the tissue expression of estrogen and progesterone receptors and the serum TNF-alpha level.

Patients and methods

The current study included 2 groups: a control group comprising 20 healthy women aged 52.21 ± 5.80 years attending the clinic for routine checkups and 40 patients with endometrial cancer aged 55.30 ± 6.21 years. Mutations in TP53 and BAT26 were evaluated using polymerase chain reaction–single-strand conformational polymorphism (PCR-SSCP) and automated sequencing while serum TNF-alpha was measured using an ELISA technique. Estrogen and progesterone receptor expression in biopsy tissue was evaluated using immunohistochemical staining.

Results

Seven of the 40 patients (17.5%) were positive for TP53 gene alterations in exon 6, while 9 patients (22.5%) were positive for TP53 alterations in exon 7. Cases positive for TP53 mutations had higher tumor stages. Ten patients (25%) showed MSI in BAT26. Nearly all patients with mutations in BAT26 had a strong family history for endometrial cancer (χ2=13.33, p<0.05). There was no positive correlation between the presence of MSI in the BAT26 gene and mutations in the TP53 gene or high serum TNF-alpha levels. Cases positive for TP53 mutations had a significantly higher level of TNF-alpha than cases negative for TP53 mutations (p<0.05). Cases showing mutations in exon 6 or 7 of TP53 showed a significantly higher intensity of immunohistochemical staining for estrogen and progesterone receptor expression in biopsy tissue than cases negative for mutations. (χ2=8.11, p<0.05).

Conclusion

Our results suggest that the development of endometrial carcinoma is probably mediated through a multi-step carcinogenesis pathway and mutation of TP53 does not necessarily result from the presence of microsatellite instability in BAT26. The high serum TNF-alpha levels detected in our patients may represent an immunological antitumor response that was particularly evident in cases positive for TP53 mutations.