Activation of extracellular regulated kinases (ERK1/2) predicts poor prognosis in urothelial bladder carcinoma and is not associated with B-Raf gene mutations

Pesticides and Bladder Cancer: Mechanisms Leading to Anti-Cancer Drug Chemoresistance and New Chemosensitization Strategies

Multiple risk factors have been associated with bladder cancer. This review focuses on pesticide exposure, as it is not currently known whether agricultural products have a direct or indirect effect on bladder cancer, despite recent reports demonstrating a strong correlation. While it is known that pesticide exposure is associated with an increased risk of bladder cancer in humans and dogs, the mechanism(s) by which specific pesticides cause bladder cancer initiation or progression is unknown. In this narrative review, we discuss what is currently known about pesticide exposure and the link to bladder cancer. This review highlights multiple pathways modulated by pesticide exposure with direct links to bladder cancer oncogenesis/metastasis (MMP-2, TGF-β, STAT3) and chemoresistance (drug efflux, DNA repair, and apoptosis resistance) and potential therapeutic tactics to counter these pesticide-induced affects.

Immunohistochemical expressions of EMT markers in pan-RAS-pERK1/2-positive tumors improve diagnosis and prognosis assessment of non-muscle invasive bladder cancer and muscle invasive bladder cancer patients

Mutation or overexpression renders pan-RAS (rat sarcoma) proteins insensitive to inactivation. Activated pan-RAS communicates signal from the cell surface receptor to activate RAS-MAPK/ERK (RAS-mitogen-activated protein kinases/extracellular signal regulated kinases) signaling and orchestrates epithelial-to-mesenchymal transition-activating transcription factors (EMT-ATFs) reprogramming to induce EMT. Owing to limited studies available in bladder cancer, the present study is taken up to examine the expressions of the EMT-associated markers in pan-RAS-pERK1/2 (pan-RAS-phosphoERK1/2)-positive well-characterized cohort of forty-two non-muscle invasive bladder cancer (NMIBC) and forty-five muscle invasive bladder cancer (MIBC) patients. Immunohistochemical staining was performed on paraffin embedded tissue sections to determine the immunolevels and cellular localization of marker proteins. Semi-quantitative expressions of pan-RAS, pERK1/2, and EMT markers (E-cadherin, Vimentin, N-cadherin, Snail, Slug Twist, and Zeb1) were statistically examined with clinicohistopathological profile of the patients using SPSS, version 20.0 software. The study documents the diagnostic relevance of immunohistochemical expressions of pan-RAS-pERK1/2/EMT-associated markers in order to stratify NMIBC and MIBC patients. Follow-up studies supported the role of altered EMT phenotype in pan-RAS-pERK1/2-activated positive tumors with disease aggressiveness. To the best of our knowledge, our study is the first concluding the impact of altered EMT phenotype via pan-RAS-pERK1/2 axis on the short survival outcome [short overall survival (OS) (p = 0.04), short progression-free survival (PFS) (p = 0.02) and short cancer-specific survival (CSS) (p = 0.03)] of muscle invasive bladder cancer patients.

Receptor Tyrosine Kinase Pathway and Infiltrating Urothelial Carcinoma

Receptor tyrosine kinase pathway is frequently searched for cancer causing mutations in tumors. Emerging targeted therapies are gleam of hope for them. Infiltrating urothelial carcinoma can have many morphological aspects according to their differentiation/variants. To evaluate KRAS, BRAF, and PIK3CA mutations and HER2, EGFR, and p16 expression, we divided urothelial carcinomas into two groups: differentiated/variants (n = 12) and conventional (n = 12). We compared results with clinical, demographic, histopathologic features and survival rates. No statistically significant results could be obtained in the comparison of histopathologic properties/survival rates with mutation analysis and EGFR, HER2, and p16 status. Differentiated/variants urothelial carcinoma showed higher EGFR expression (P < 0.001). Glandular differentiation was the most frequent type, followed by squamous and sarcomatoid differentiation. We observed the most common mutation at KRAS with a propensity for urothelial carcinoma with glandular differentiation. More than one mutation/high protein expression was seen in some tumors. Targeted therapies for KRAS mutation can be effective at urothelial carcinoma with glandular differentiation. Heterologous expression of relevant proteins and genes can be a cause for targeted treatment obstacle. The determination of the molecular characters of tumors is a guide in creating targeted treatment algorithms and in choosing the patient.

Expression of Spred2 in the urothelial tumorigenesis of the urinary bladder

Aberrant activation of the Ras/Raf/ERK (extracellular-signal-regulated kinase)-MAPK (mitogen-activated protein kinase) pathway is involved in the progression of cancer, including urothelial carcinoma; but the negative regulation remains unclear. In the present study, we investigated pathological expression of Spred2 (Sprouty-related EVH1 domain-containing protein 2), a negative regulator of the Ras/Raf/ERK-MAPK pathway, and the relation to ERK activation and Ki67 index in various categories of 275 urothelial tumors obtained from clinical patients. In situ hybridization demonstrated that Spred2 mRNA was highly expressed in high-grade non-invasive papillary urothelial carcinoma (HGPUC), and the expression was decreased in carcinoma in situ (CIS) and infiltrating urothelial carcinoma (IUC). Immunohistochemically, membranous Spred2 expression, important to interact with Ras/Raf, was preferentially found in HGPUC. Interestingly, membranous Spred2 expression was decreased in CIS and IUC relative to HGPUC, while ERK activation and the expression of the cell proliferation marker Ki67 index were increased. HGPUC with membranous Spred2 expression correlated significantly with lower levels of ERK activation and Ki67 index as compared to those with negative Spred2 expression. Thus, our pathological findings suggest that Spred2 counters cancer progression in non-invasive papillary carcinoma possibly through inhibiting the Ras/Raf/ERK-MAPK pathway, but this regulatory mechanism is lost in cancers with high malignancy. Spred2 appears to be a key regulator in the progression of non-invasive bladder carcinoma.

Image-guided photo-therapeutic nanoporphyrin synergized HSP90 inhibitor in patient-derived xenograft bladder cancer model

Photodynamic therapy is a promising and effective non-invasive therapeutic approach for the treatment of bladder cancers. Therapies targeting HSP90 have the advantage of tumor cell selectivity and have shown great preclinical efficacy. In this study, we evaluated a novel multifunctional nanoporphyrin platform loaded with an HSP90 inhibitor 17AAG (NP-AAG) for use as a multi-modality therapy against bladder cancer. NP-AAG was efficiently accumulated and retained at bladder cancer patient-derived xenograft (PDX) over 7 days. PDX tumors could be synergistically eradicated with a single intravenous injection of NP-AAG followed by multiple light treatments within 7 days. NP-AAG mediated treatment could not only specifically deliver 17AAG and produce heat and reactive oxygen species, but also more effectively inhibit essential bladder cancer essential signaling molecules like Akt, Src, and Erk, as well as HIF-1α induced by photo-therapy. This multifunctional nanoplatform has high clinical relevance and could dramatically improve management for bladder cancers with minimal toxicity.

Potential role of AKT/mTOR signalling proteins in hairy cell leukaemia: association with BRAF/ERK activation and clinical outcome

The potential role of AKT/mTOR signalling proteins and its association with the Raf-MEK-ERK pathway was investigated in hairy cell leukaemia (HCL). BRAFV600E expression and activated forms of AKT, mTOR, ERK1/2, p70S6k and 4E-BP1 were immunohistochemically assessed in 77 BM biopsies of HCL patients and correlated with clinicopathological and BM microvascular characteristics, as well as with c-Caspase-3 levels in hairy cells. Additionally, we tested rapamycin treatment response of BONNA-12 wild-type cells or transfected with BRAFV600E. Most HCL cases expressed p-p70S6K and p-4E-BP1 but not p-mTOR, being accompanied by p-ERK1/2 and p-AKT. AKT/mTOR activation was evident in BONNA-12 cells irrespective of the presence of BRAFV600E mutation and was implicated in cell proliferation enhancement. In multivariate analysis p-AKT/p-mTOR/p-4E-BP1 overexpression was an adverse prognostic factor for time to next treatment conferring earlier relapse. When p-AKT, p-mTOR and p-4E-BP1 were examined separately only p-4E-BP1 remained significant. Our findings indicate that in HCL, critical proteins up- and downstream of mTOR are activated. Moreover, the strong associations with Raf-MEK-ERK signalling imply a possible biologic interaction between these pathways. Most importantly, expression of p-4E-BP1 alone or combined with p-AKT and p-mTOR is of prognostic value in patients with HCL.

Prognostic values of ERK1/2 and p-ERK1/2 expressions for poor survival in non-small cell lung cancer

The extracellular-regulated kinase (ERK) 1/2, as a member of the mitogen-activated protein kinase family, plays a crucial role in the development of cancer. However, little is known about the prognostic value of ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) in non-small cell lung cancer (NSCLC). Thus, we investigated their prognostic values and analyzed the associations between their expressions and clinicopathological features in NSCLC patients. We examined ERK1/2 and p-ERK1/2 expressions via immunohistochemistry in 183 NSCLC samples. The prognostic significances of protein expression were evaluated with univariate and multivariate survival analysis. Of the specimens, 44.8 and 44.3 % revealed positive staining for ERK1/2 and p-ERK1/2, respectively. There were 24.6 % specimens with both ERK1/2 and p-ERK1/2-positive expression. The results showed p-ERK1/2-positive expression was an independent prognostic factor for poor overall survival (OS) in NSCLC patients on both univariate analysis (p < 0.0001) and multivariate analysis (p = 0.0000). Meanwhile, the positive expression of both proteins was also associated with poor OS (p = 0.002). With respect to clinicopathological features, the tumor differentiation was significantly associated with the positivity of ERK1/2, p-ERK1/2, and both proteins, while histological type was only related to ERK1/2. However, there were no significant differences between the expressions and other clinical features, such as gender, age, smoking, tumor-node-metastasis (TNM) stage, lymph node metastasis, and treatments. The p-ERK1/2-positive expression was associated with adverse outcomes, and the positive expression of both ERK1/2 and p-ERK1/2 proteins was also related to poor OS. Therefore, the positivity of p-ERK1/2 expression may serve as a vital biomarker in the development of NSCLC.

Molecular biology of bladder cancer: new insights into pathogenesis and clinical diversity

Urothelial carcinoma of the bladder comprises two long-recognized disease entities with distinct molecular features and clinical outcome. Low-grade non-muscle-invasive tumours recur frequently but rarely progress to muscle invasion, whereas muscle-invasive tumours are usually diagnosed de novo and frequently metastasize. Recent genome-wide expression and sequencing studies identify genes and pathways that are key drivers of urothelial cancer and reveal a more complex picture with multiple molecular subclasses that traverse conventional grade and stage groupings. This improved understanding of molecular features, disease pathogenesis and heterogeneity provides new opportunities for prognostic application, disease monitoring and personalized therapy.

Extracellular signal-regulated kinase (ERK) expression and activation in mobile tongue squamous cell carcinoma: associations with clinicopathological parameters and patients survival

Extracellular signal-regulated kinase (ERK) has been considered as a critical regulator of diverse cellular processes such as proliferation, survival and motility, being implicated in the malignant transformation in several tissue types. The present study aimed to evaluate the clinical significance of total ERK1 (t-ERK1) and phosphorylated ERK1/2 (p-ERK1/2) protein expression in mobile tongue squamous cell carcinoma (SCC). t-ERK1 and p-ERK1/2 protein expression in tumour cells and infiltrating the tumour microenvironment lymphoid cells was assessed immunohistochemically on 47 mobile tongue SCC tissue samples and was analyzed in relation with clinicopathological characteristics, overall and disease-free patients' survival. Enhanced nuclear t-ERK1 and p-ERK1/2 expression in tumour cells was associated with the absence of perineural invasion (p = 0.043) and shorter overall patients' survival (log-rank test, p = 0.028), respectively. Enhanced t-ERK1 expression in infiltrating lymphoid cells was significantly associated with female gender, absence of vascular and perineural invasion, lymph node metastases and early depth of invasion (p = 0.008, p = 0.019, p = 0.011, p = 0.036 and p = 0.001, respectively), as well as with longer disease-free survival times (log-rank test, p = 0.038). Enhanced p-ERK1/2 expression in infiltrating lymphoid cells was significantly associated with the presence of vascular invasion and lymph node metastases (p = 0.019 and p = 0.004, respectively) and shorter overall patients' survival (log-rank test, p = 0.013). In multivariate analysis, p-ERK1/2 expression in tumour cells and infiltrating lymphoid cells was identified as independent prognostic factors of overall survival (Cox regression analysis, p = 0.045 and p = 0.032, respectively). The present study supported evidence that ERK signalling pathway may exert a potential role in the pathophysiological aspects of the mobile tongue SCC, presenting also potential utility as a biomarker for patients' survival and reinforcing the development of novel anti-cancer therapies targeting ERK signalling cascade in this type of human malignancy.

Low RKIP expression associates with poor prognosis in bladder cancer patients

Urothelial bladder cancer (UBC) is a heterogeneous type of disease. It is urgent to screen biomarkers of tumour aggressiveness in order to clarify the clinical behaviour and to personalize therapy in UBC patients. Raf kinase inhibitory protein (RKIP) is a metastasis suppressor, and its downregulation is associated with metastatic events in an increasing number of solid tumours. We evaluated the clinical and prognostic significance of RKIP expression in patients with high risk of progression UBC. Using immunohistochemistry, we determined RKIP expression levels in a series of 81 patients with high-grade pT1/pTis or muscle-invasive UBC. Staining of CD31 and D2-40 was used to assess blood and lymphatic vessels, in order to distinguish between blood and lymphatic vessel invasion (LVI). We found that 90 % of pT1/pTis tumours, 94 % of non-muscle invasive papillary tumours and 76 % of the cases without LVI occurrence expressed RKIP in >10 % of cells. In this group, we observed a subgroup of tumours (42 %) in which the tumour centre was significantly more intensely stained than the invasion front. This heterogeneous pattern was observed in 63 % of the cases with LVI. Low RKIP expression was associated with poorer 5-year disease-free and overall survival rates, and remained as an independent prognostic factor for disease-free survival. Loss of RKIP expression may be an important prognostic factor for patients with high risk of progression bladder cancer.

Side population in human non-muscle invasive bladder cancer enriches for cancer stem cells that are maintained by MAPK signalling

Side population (SP) and ABC transporter expression enrich for stem cells in numerous tissues. We explored if this phenotype characterised human bladder cancer stem cells (CSCs) and attempted to identify regulatory mechanisms. Focusing on non-muscle invasive bladder cancer (NMIBC), multiple human cell lines were used to characterise SP and ABC transporter expression. In vitro and in vivo phenotypic and functional assessments of CSC behaviour were undertaken. Expression of putative CSC marker ABCG2 was assessed in clinical NMIBC samples (n = 148), and a role for MAPK signalling, a central mechanism of bladder tumourigenesis, was investigated. Results showed that the ABCG2 transporter was predominantly expressed and was up-regulated in the SP fraction by 3-fold (ABCG2(hi)) relative to the non-SP (NSP) fraction (ABCG2(low)). ABCG2(hi) SP cells displayed enrichment of stem cell markers (Nanog, Notch1 and SOX2) and a three-fold increase in colony forming efficiency (CFE) in comparison to ABCG2(low) NSP cells. In vivo, ABCG2(hi) SP cells enriched for tumour growth compared with ABCG2(low) NSP cells, consistent with CSCs. pERK was constitutively active in ABCG2(hi) SP cells and MEK inhibition also inhibited the ABCG2(hi) SP phenotype and significantly suppressed CFE. Furthermore, on examining clinical NMIBC samples, ABCG2 expression correlated with increased recurrence and decreased progression free survival. Additionally, pERK expression also correlated with decreased progression free survival, whilst a positive correlation was further demonstrated between ABCG2 and pERK expression. In conclusion, we confirm ABCG2(hi) SP enriches for CSCs in human NMIBC and MAPK/ERK pathway is a suitable therapeutic target.

A comprehensive immunohistochemical and molecular approach to the PI3K/AKT/mTOR (phosphoinositide 3-kinase/v-akt murine thymoma viral oncogene/mammalian target of rapamycin) pathway in bladder urothelial carcinoma

What's known on the subject? and What does the study add? A few published studies investigating single or various PI3K/AKT/mTOR signalling components have produced inconsistent results. Moreover, PI3K regulatory subunit p85a and activated p70S6K expression levels have not been previously examined in urothelial carcinoma (UC). The present study addresses simultaneously all key members of PI3K/AKT/mTOR signalling cascade supporting a differential implication of PI3K/AKT/mTOR pathway components in urothelial tumorigenesis. Furthermore, we propose p-4E-BP1 as a potential prognostic marker in UC, which might assist the selection of patients more likely to benefit from chemotherapy regimens based on PI3K/AKT/mTOR pathway inhibition. Finally, the present study indicates PIK3CA/AKT1 mutational status as a potential predictive marker for time-to-recurrence.

OBJECTIVE

• To perform a comprehensive simultaneous assessment of all key members of phosphoinositide 3-kinase/v-akt murine thymoma viral oncogene/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway along with AKT homolog 1 (AKT1) and PIK3 catalytic alpha polypeptide (PIK3CA) mutations in bladder urothelial carcinoma (UC). • Published information is limited to a few studies looking into single or various combinations of members of this pathway with inconsistent results. In particular the expression status of phosphorylated (p-)p70S6 kinase (p70S6K) and p85a subunit of PI3K has not been tested in UC.

PATIENTS AND METHODS

• Paraffin-embedded transurethral resection tissue from 113 patients with UC was investigated for the association of p85aPI3K, p-AKT, p-mTOR, p-p70S6K and p-4E-BP1 (eukaryotic initiation factor 4E-binding protein 1) expression status, as well as PIK3CA and AKT1 mutations with p-extracellular signal-regulated kinase 1/2 (ERK1/2), fibroblast growth factor receptor 3 (FGFR3), pathological features, recurrence and cancer-specific survival.

RESULTS

• With the exception of p-p70S6K, all others components of the PI3K/AKT/mTOR pathway were upregulated in UCs as compared with normal urothelium. • p-mTOR expression strongly correlated with its upstream p-AKT and marginally with its downstream p-p70S6K. p85aPI3K and p-ERK1/2 levels were also marginally correlated. • PIK3CA and AKT1 mutations were distinctly uncommon and mutually exclusive, without any association with pathological features. However, the presence of AKT1 mutations was associated with increased FGFR3 levels and was restricted to p85aPI3K immunonegative cases, whereas PIK3CA mutant cases had marginally lower p85aPI3K levels. • The presence of PIK3CA single or combined with AKT1 mutations was associated with shorter recurrence-free survival in univariate survival analysis. An inverse relationship was established between p-4E-BP1 immunopositivity and histological grade or T category, as well as between p-p70S6K levels and T category, the latter relationship being of marginal significance. • p-4E-BP1 nuclear expression was marginally associated with the presence of lymphovascular invasion and adversely affected survival in multivariate, but not in univariate analysis.

CONCLUSIONS

• PI3K/AKT/mTOR signalling components appear to be differentially implicated in urothelial tumorigenesis and, with the exception of p85aPI3K, are unrelated to the PIK3CA or AKT1 mutational status. • Our findings propose p-4E-BP1 as a potential prognostic marker in UC independent of its association with pathological features, which might assist the selection of patients more likely to benefit from PI3K/AKT/mTOR axis inhibition. • PIK3CA/AKT1 mutational status may have a place in the prediction of time-to-recurrence.

Transcriptional Modulation of the ERK1/2 MAPK and NF-κB Pathways in Human Urothelial Cells After Trivalent Arsenical Exposure: Implications for Urinary Bladder Cancer

Chronic exposure to drinking water contaminated with inorganic arsenic (iAs) is associated with an increased risk of urinary bladder (UB) cancers in humans. The exact role of specific iAs metabolite(s) in As-mediated carcinogenesis remains largely unknown. Experimental evidence suggests that trivalent arsenicals, namely arsenite (iAsIII) and two of its metabolites, monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII), are possible proximate UB carcinogens. Here, we used a transcriptomics approach to examine perturbed molecular pathways in a human urothelial cell line (UROtsa) after short-term exposure to iAsIII, MMAIII and DMAIII. Molecular pathways containing genes that encode proteins implicated in UB cancer development were perturbed by both MMAIII and DMAIII. These pathways included those of the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase (ERK 1/2 MAPK) and nuclear factor kappa beta (NF-κB). Together, these results may inform the current understanding of effects in the UB induced by acute As exposure and the relationship of these effects with As-mediated carcinogenesis.

pERK activation in esophageal carcinomas: clinicopathological associations

MAPK (mitogen-activated protein kinase) pathway is considered a control regulator in various malignant tumors but its role in esophageal carcinomas remains elusive. In our study, we examined the possible prognostic significance of MAPK pathway in human esophageal cancer. We searched for mutations in exons 18-21 of EGFR gene, codons 12 and 13 of K-RAS gene and exon 15 of B-RAF gene by high resolution melting analysis (HRMA) and pyrosequencing in 44 esophageal carcinomas. Immunohistochemistry was performed in 29 cases in order to evaluate expression levels of pERK (extracellular-signal regulated kinase). In one laser microdissected squamous cell carcinoma, a somatic K-RAS mutation at codon 12 was detected, whereas none of the cases displayed mutations in EGFR and B-RAF genes. Elevated nuclear as well as cytoplasmic pERK expression (100% and 62% of cases respectively) was observed independently of EGFR and B-RAF mutational status. Increasing pERK nuclear and cytoplasmic expression as well as the intensity of nuclear staining was found to be significantly correlated with tumor grade in univariate and multivariate statistical analysis. Our findings depict the presence of activated ERK despite the low frequency of upstream alterations, implicating ERK activation in the acquisition of a more aggressive phenotype in esophageal cancer.

Mutations in FGFR3 and PIK3CA, singly or combined with RAS and AKT1, are associated with AKT but not with MAPK pathway activation in urothelial bladder cancer

Different members of the phosphoinositide 3 kinase--serine threonine protein kinase (PI3K-AKT) pathway are altered in bladder cancer. Fibroblast growth factor receptor 3 (FGFR3) mutations characterize the low-grade tumors, and RAS genes are mutated in approximately 13% of all bladder tumors. Interestingly, a percentage of bladder tumors have alterations in more than 1 PI3K-AKT or rat sarcoma viral oncogene homolog-RAF mitogen activated protein kinase (RAS-MAPK) pathway gene or their upstream regulators, but some combinations are mutually exclusive. We analyzed mutations in FGFR3, phosphoinositide 3 kinase catalytic alpha polypeptide (PIK3CA), v-akt murine thymoma viral oncogene homolog 1 (AKT1), v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS), v-Ha-ras Harvey rat sarcoma viral oncogene homolog (HRAS), and v-raf murine sarcoma viral oncogene homolog B1 (BRAF) in 88 urothelial cell carcinomas and the immunohistochemical expression of phospho-v-akt murine thymoma viral oncogene homolog (AKT) and mitogen-activated protein kinase 1 and 2 (pERK1/2) in 80 and 77 urothelial cell carcinomas, respectively. Approximately 43% and 20.5% of tumors presented 1 and 2 mutated genes, respectively. FGFR3 mutations were more frequent alone, whereas PIK3CA mutations were associated with another mutated gene (FGFR3 and KRAS). Overall, mutated FGFR3 (FGFR3(mut)) and mutated FGFR3 (FGFR3(mut))-mutated PIK3CA (PIK3CA(mut)) genotypes were associated with low-grade bladder tumors and mutated PIK3CA (PIK3CA(mut))-mutated KRAS (KRAS(mut)) and mutated AKT1 (AKT1(mut)) were only present in high-grade tumors. There are no mutated FGFR3 (FGFR3(mut))-mutated RAS (RAS(mut)) nor mutated PIK3CA (PIK3CA(mut))-mutated AKT1 (AKT1(mut)) combinations. Fifty percent and 56% of tumors showed high levels of pAKT and pERK1/2, respectively. High levels of pAKT were associated with total mutations, FGFR3(mut), and PIK3CA(mut) tumors but not with tumor grade or stage. Wild-type tumors presented significantly higher pERK1/2 expression. Mutations in FGFR3 and FGFR3-PIK3CA but not single PIK3CA mutations characterize low-grade bladder tumors. Single FGFR3 or PIK3CA mutations and the different mutation combinations FGFR3-PIK3CA/AKT1 and PIK3CA-RAS can activate the AKT but not the MAPK pathway. Other genes different from FGFR3 may be related with the pERK activation in bladder tumors.

Dihydrotestosterone upregulates the expression of epidermal growth factor receptor and ERBB2 in androgen receptor-positive bladder cancer cells

Androgen receptor (AR) signals play important roles in bladder carcinogenesis and tumor progression. Activation of the epidermal growth factor receptor (EGFR) family, including EGFR and ERBB2, leads to bladder cancer cell growth and correlates with poor patients' prognosis. However, cross talk between AR and EGFR/ERBB2 pathways in bladder cancer remains poorly understood. In AR-positive bladder cancer UMUC3 and TCC-SUP cells, dihydrotestosterone (DHT) increased the expression of EGFR and ERBB2 both in mRNA and in protein levels, and an anti-androgen hydroxyflutamide antagonized the effect of DHT. The necessity of AR was confirmed by silencing the receptor, using short hairpin RNA (shRNA), in UMUC3 cells, as well as by expressing the receptor in AR-negative 5637 cells. Of note were much higher basal levels of EGFR and ERBB2 in UMUC3-control-shRNA than in UMUC3-AR-shRNA and those of EGFR in 5637-AR than in 5637-V. DHT additionally upregulated the levels of phosphorylation of EGFR (pEGFR) and its downstream proteins AKT (pAKT) and ERK1/2 (pERK), induced by EGF treatment, in AR-positive cells. Immunohistochemistry on cystectomy specimens showed strong associations between expressions of AR and EGFR (P=0.0136), pEGFR (P=0.0041), ERBB2 (P=0.0331), or pERK (P=0.0274), but not of pAKT (P=0.5555). The Kaplan-Meier and log-rank tests further revealed that positivity of AR (P=0.0005), EGFR (P=0.2425), pEGFR (P=0.1579), ERBB2 (P=0.2997), or pERK (P=0.1270) and negativity of pAKT (P=0.0483) were associated with tumor progression. Our results indicate that AR activation upregulates the expression of EGFR and ERBB2 in bladder cancer cells. AR signals may thus contribute to the progression of bladder cancer via regulation of the EGFR/ERBB2 pathways.