p21(WAF-1/CIP-1), a downstream regulator of functional p53 loss, in transitional cell carcinoma of urothelium

WDR74 induces nuclear β-catenin accumulation and activates Wnt-responsive genes to promote lung cancer growth and metastasis

Lung cancer has been notorious for its lack of advance in clinical therapy, urging for effective therapeutic targets. WD repeat-containing protein 74 (WDR74) has previously been implicated in tumorigenesis, but its mechanistic functions remain not well understood. Herein, WDR74 expression was observed to be increased upon lung cancer progression from healthy normal tissues to the primary cancer and further to the metastatic cancer. Through gain- and loss-of-function approaches, we found that WDR74 regulated lung cancer cell proliferation, cell cycle progression, chemoresistance and cell aggressiveness in vitro. Moreover, a xenograft mouse model disclosed that WDR74 knockout inhibited lung cancer growth and metastasis, whereas WDR74 overexpression reciprocally enhanced these characteristics. Mechanistically, WDR74 promoted nuclear β-catenin accumulation and drove downstream Wnt-responsive genes, thus revealing that WDR74 activated the Wnt/β-catenin signaling pathway. Collectively, WDR74 inducing nuclear β-catenin accumulation and driving the downstream Wnt-responsive genes expression facilitates lung cancer growth and metastasis. WDR74 can serve as a candidate target for the prevention and treatment of lung cancer in clinic.

WDR74 modulates melanoma tumorigenesis and metastasis through the RPL5-MDM2-p53 pathway

The key molecules and underlying mechanisms of melanoma metastasis remain poorly understood. Using isobaric tag for relative and absolute quantitation (iTRAQ) proteomic screening, probing of patients' samples, functional verification, and mechanistic validation, we identified the important role of the WD repeat-containing protein 74 (WDR74) in melanoma progression and metastasis. Through gain- and loss-of-function approaches, WDR74 was found to promote cell proliferation, apoptosis resistance, and aggressive behavior in vitro. Moreover, WDR74 contributed to melanoma growth and metastasis in vivo. Mechanistically, WDR74 modulates RPL5 protein levels and consequently regulates MDM2 and insulates the ubiquitination degradation of p53 by MDM2. Our study is the first to reveal the oncogenic role of WDR74 in melanoma progression and the regulatory effect of WDR74 on the RPL5-MDM2-p53 pathway. Collectively, WDR74 can serve as a candidate target for the prevention and treatment of melanoma in the clinic.

Polymorphisms in cell cycle regulatory genes, urinary arsenic profile and urothelial carcinoma

INTRODUCTION

Polymorphisms in p53, p21 and CCND1 could regulate the progression of the cell cycle and might increase the susceptibility to inorganic arsenic-related cancer risk. The goal of our study was to evaluate the roles of cell cycle regulatory gene polymorphisms in the carcinogenesis of arsenic-related urothelial carcinoma (UC).

METHODS

A hospital-based case-controlled study was conducted to explore the relationships among the urinary arsenic profile, 8-hydroxydeoxyguanosine (8-OHdG) levels, p53 codon 72, p21 codon 31 and CCND1 G870A polymorphisms and UC risk. The urinary arsenic profile was determined using high-performance liquid chromatography (HPLC) and hydride generator-atomic absorption spectrometry (HG-AAS). 8-OHdG levels were measured by high-sensitivity enzyme-linked immunosorbent assay (ELISA) kits. Genotyping was conducted using polymerase chain reaction-restriction fragment length polymerase (PCR-RFLP).

RESULTS

Subjects carrying the p21 Arg/Arg genotype had an increased UC risk (age and gender adjusted OR=1.53; 95% CI, 1.02-2.29). However, there was no association of p53 or CCND1 polymorphisms with UC risk. Significant effects were observed in terms of a combination of the three gene polymorphisms and a cumulative exposure of cigarette smoking, along with the urinary arsenic profile on the UC risk. The higher total arsenic concentration, monomethylarsonic acid percentage (MMA%) and lower dimethylarsinic acid percentage (DMA%), possessed greater gene variant numbers, had a higher UC risk and revealed significant dose-response relationships. However, effects of urinary 8-OHdG levels combined with three gene polymorphisms did not seem to be important for UC risk.

CONCLUSIONS

The results showed that the variant genotype of p21 might be a predictor of inorganic arsenic-related UC risk.

Alteration of p53 pathway in squamous cell carcinoma of the head and neck: impact on treatment outcome in patients treated with larynx preservation intent

PURPOSE

To identify the role of p53 pathway alteration(s) as predictors of treatment outcome in patients with advanced, resectable, squamous cell carcinoma (SCC) of the larynx and pharynx treated with larynx preservation (LP) intent.

PATIENTS AND METHODS

Seventy-one patients treated on two consecutive LP protocols were studied based on availability of representative tissues. We analyzed the expression pattern of p53, its upstream regulator mdm2, and downstream transcriptional target p21/WAF1 by immunohistochemistry. Positive phenotype was defined as >or= 20% of tumor cells showing nuclear immunoreactivity. Results were correlated with treatment outcomes.

RESULTS

Positive phenotype was observed in 35 (49%) of 71 cases for p53, in 52 (74%) of 70 for mdm2, and in 37 (54%) of 68 for p21. There was no correlation between p53 phenotype and p21 nuclear accumulation. The mdm2-negative phenotype was most predictive of major response at the primary tumor site (P =.088). p53-positive phenotype was associated with worse local control with LP (LCLP; 49% v 23%, P =.053) and inferior overall survival (OS; 51% v 29%, P =.017) at 5 years. On Cox regression analysis, p53-positive phenotype predicted inferior OS (P =.033) and showed a trend for worse LCLP (P =.102). When analyzed in a multivariate model as continuous variables, p53 showed a stronger correlation with inferior OS (P <.01), and mdm2 was associated with worse OS (P <.01).

CONCLUSION

Among the three markers studied, our data support p53 phenotype as the most informative predictor of unfavorable outcomes in the LP setting, and suggest a role for mdm2 phenotype that requires further exploration. Our analysis does not support a p53-dependent mechanism for p21 expression. Prospective and larger studies are necessary before integration of these molecular markers as part of molecular staging and predictors for organ preservation or other outcomes.

p21 gene codon 31 polymorphism is associated with bladder cancer

The function of p21 is related to cell apoptosis, progression and malignancies. It is thought that p21 is related to cancer formation but is not related to tumor grade. We aimed to investigative the polymorphism of p21 codon 31 as a candidate for the genetic marker of bladder cancer and its progression. The distribution was analyzed in 53 bladder cancer patients, 119 healthy controls in Taiwanese patients. Polymerase chain reaction based restriction analysis was used for the study of the association of p21 codon 31 polymorphism with bladder cancer. There was a significant difference in p21 codon 31 polymorphism between the control and the cancer patients (p < 0.01). The arginine form was prominent in the cancer patient (per copy of the A allele, odds ratio = 2.03, 95% confidence interval = 1.23-3.37). Furthermore, the distribution of this polymorphism was significantly different from non-invasive to invasive bladder cancer (p < 0.05). Serine heterozygote was more prominent in the invasive group with 25 to 1% respectively when compared with the non-invasive group. The polymorphism of p21 codon 31 is associated with bladder cancer. An individual possessing one allele of arginine form in p21 codon 31 has a higher risk of developing bladder cancer than the serine form. Although the mechanism is unclear, our results show p21 gene is associated with tumor grade.