Prognostic significance of CD44, platelet-derived growth factor receptor alpha, and cyclooxygenase 2 expression in renal cell carcinoma

Expression of growth factors and their receptors in the primary renal cell carcinoma: new data and review

Introduction

The aim of our study was to investigate expression levels and the prognostic value of multiple growth factors and their receptors in the primary tumor cells of renal cell carcinoma (RCC).

Material and methods

Expression of vascular endothelial growth factor (VEGF)A, fibroblast growth factor (FGF)2, vascular endothelial growth factor receptor (VEGFR)1, VEGFR2, FGFR1, FGFR2, platelet-derived growth factor receptor (PDGFR)α, and PDGFRβ was investigated in 65 primary RCC specimens by immuhistochemical staining using the appropriate antibodies. Expression levels were evaluated by the semi-quantitative method. A search for correlations of expression levels of investigated growth factors and receptors with RCC features and patients outcomes was performed.

Results

Expression of all growth factors and their receptors was detected both on the surface and in the cytoplasm of the primary tumor cells in RCC patients. The expression of all analyzed factors was interconnected. FGFR2 expression correlated with the largest number of other growth factors and receptors. A strong correlation was revealed between high expression of the studied markers, high Fuhrman grade, and advanced RCC stages. In a univariate analysis overexpression of VEGFR2 (p <0.0001) and FGFR2 (p = 0.014) had negative influence on cancer-specific survival.

Conclusions

Expression of growth factors and tyrosine kinase receptors in the primary tumor cells is strongly interconnected and associated with unfavorable features of RCC.

Association of beta-catenin and CD44 in the development of renal cell carcinoma

INTRODUCTION AND OBJECTIVE

Renal cell carcinoma (RCC) accounts for approximately 3% of all cancers. Approximately 25%-30% of patients present with metastatic disease at the time of diagnosis, and metastatic RCC is a treatment-resistant malignancy. Altered expression of cell adhesion molecules such as CD44 on tumor cells suggests a pathogenetic mechanism for tumor metastasis and may provide prognostic information for particular tumors. These cell matrix interactions of CD44 play a role in tumor cell invasion and metastasis. The Wnt/beta-catenin pathway turned out to be a promising target as it is involved in the regulation of cell proliferation, differentiation and apoptosis induction.

METHOD

In this study, the expression of beta-catenin and CD44 was analyzed in primary renal cell carcinoma (RCC) samples to understand their association with development of the disease. For this purpose, immunohistochemical expression analysis of beta-catenin and CD44 was performed in 30 primary RCC histological samples and normal kidney tissues in different subtypes at different clinical stages of Indian patients (year: 2017-2019).

RESULT

Most of the patients who presented were diagnosed as clear cell carcinoma and it was observed that expression of CD44 was high in patients with high stage tumors. Also beta-catenin was increased in advanced grade tumors, but there was insignificant correlation between high expression of molecules and survival or recurrence of disease.

CONCLUSION

Both cd44 and beta-catenin activation was noted in patients with clear cell carcinoma, more in advanced tumors. Both can be promising targets for treatment in clear cell RCCs.

Current updates and future perspectives on the management of renal cell carcinoma

Renal cell carcinoma (RCC) refers to renal-epithelial cancer, which represents over 90% of kidney cancer and is a cause for cancer related deaths in the world. Studies suggested somatic VHL mutations to be the cause for the occurrence of cancer, but with the time, more latest genomic and biological studies have detected variation in epigenetic regulatory genes and showed significant heterogeneity of the intratumor that may lead to strategies of diagnostic, predictive, and therapeutic importance. Immune dysfunction is responsible for almost all types of renal cancer, and angiogenesis and immunosuppression function together in the tumor microenvironment of renal cell carcinoma (RCC). Over the past few years, advancement in the management of the RCC has finally revolutionized with the arrival of the entrapped immune inhibitors which particularly concentrated on the receptor (programmed cell death-1) and focus on the new generation receptor i.e. TKRI (tyrosine-kinase receptor inhibitors). The present review deals with the comprehensive review of RCC and emphasizes on its types, pathogenesis and advancement in these diseases. This review also overviews the role of innate and adaptive immune response-related mechanism, the function of cancer stem cell in this diseases, therapeutic targeted drugs and hormonal signaling pathways as an emerging strategy in the management of the renal cancer.

Serum Platelet-Derived Growth Factor Is Significantly Lower in Patients with Lung Cancer and Continued to Decrease After Platinum-Based Chemotherapy

Objective

This study aimed to investigate the diagnosis and prediction of serum platelet-derived growth factor (PDGF) level in patients with lung cancer (LC).

Methods

Serum concentrations of PDGF-AA and PDGF-AB/BB were determined via Luminex assay in 210 patients with non-small cell lung cancer (NSCLC), 33 patients with small cell lung cancer (SCLC), and 168 healthy controls.

Results

The serum levels of PDGF-AA and PDGF-AB/BB were lower in patients with NSCLC (P < 0.05) and SCLC (P < 0.05), compared to healthy controls. The concentration of PDGF-AA or PDGF-AB/BB continued to markedly decrease in NSCLC after therapy with platinum-based chemotherapy (P < 0.05). The median survival times were 29 and 38 months in patients with NSCLC who received PDGF-AA < 30 ng/mL and PDGF-AA ≥ 30 ng/mL (P = 0.0078), and 26 and 38 months in patients with NSCLC who received PDGF-AB/BB < 42 ng/mL and PDGF-AB/BB ≥ 42 ng/mL (P = 0.0001), respectively. At the individual protein level, PDGF-AA and PDGF-AB/BB had better diagnostic values for NSCLC (AUC = 0.905, AUC = 0.922, respectively).

Conclusion

Serum PDGF may be a potential biomarker for diagnosis of patients with NSCLC and SCLC. However, the prognostic value of serum PDGF in patients with NSCLC harboring mutations and different therapies requires additional investigation.

Cancer stem cell markers predict a poor prognosis in renal cell carcinoma: a meta-analysis

Background

Relevant markers of CSCs may serve as prognostic biomarkers of RCC. However, their actual prognostic significance remains inconclusive. Thus, a meta-analysis was performed to reevaluate the association of CSCs-relevant markers (CXCR4, CD133, CD44, CD105) expression with RCC prognosis more precisely.

Methods

PubMed and Embase were searched to look for eligible studies. The pooled hazard ratios (HR) with 95% confidence intervals (95% CI) were used to reassess the association of CSCs markers expression and RCC prognosis of overall survival (OS), cancer-specific survival (CSS), disease-free survival (DFS), and progression-free survival (PFS).

Results

There were 25 relevant articles, encompassing 2673 RCC patients, eligible for meta-analysis. Overall pooled analysis suggested that high CSCs markers expression predicted poor OS (HR, 2.10, 95% CI: 1.73–2.55) and DFS (HR, 3.77, 95% CI: 2.30–6.19). High CXCR4 expression predicted worse OS (HR, 2.57, 95% CI: 1.95–3.40), CSS (HR,1.97, 95% CI: 1.50–2.59), and DFS (HR, 5.82, 95% CI: 3.01–11.25). CD44 over-expression correlated with a poor OS(HR,1.58, 95% CI: 1.14–2.18), CSS (HR, 2.58, 95% CI: 1.27–5.23), and DFS (HR, 4.49, 95% CI: 2.12–9.53) in RCC patients. CD133 was an independent favorable prognostic factor for CSS (HR, 0.4, 95% CI: 0.29–0.54).

Conclusions

The presence of CSCs markers correlates with poor RCC outcome. CSCs may be potentially utilized as prognostic markers to stratify RCC patients, probably representing also a novel potential therapeutic target.

COX-2 Expression in Renal Cell Carcinoma and Correlations with Tumor Grade, Stage and Patient Prognosis

BACKGROUND

Cyclooxygenase 2 (COX-2) is important as an enzyme in the pathway leading to the production of prostaglandin E2 (PGE2) and arachidonic acid. This pathway is known to play a role in inflammation, tumor growth, invasiveness and metastasis, inhibition of apoptosis and angiogenesis. Inhibition of COX-2 has been shown to be a promising antitumor and antiangiogenic strategy in several tumor types, including renal cell carcinoma (RCC). Therefore, we decided to evaluate the immunohistochemical expression of this marker and its association with several clinicopathological characteristics in a series of cases.

MATERIALS AND METHODS

COX-2 expression was examined immunohistochemically in tumor tissues obtained from 96 patients who underwent radical (94 cases) or partial (2 cases) nephrectomy. Correlations between COX-2 expression and clinicopathologic findings including pathologic stage, nuclear grade and other indicator of prognosis were examined.

RESULTS

Of 96 tumors, 20.9% were positive for COX-2 expression. A correlation was found between COX-2 expression and tumor histological subtype (P=0.03).The papillary subtype showed maximum expression of this marker (43.8%) and the clear subtype minimum (14.7%). There were also possible links between COX-2 expression and pathologic stage, nuclear grade and nodal involvement but the results were not statistically significant (P=0.8, P= 0.14 and P=0.06, respectively). No correlation was found between COX2 expression and patient age, gender, tumor size, metastasis or survival.

CONCLUSIONS

In our study, COX-2 expression was correlated with the histological subtype of RCC. Additional research is required to determine the link between COX-2 expression and prognosis and also evaluation of probable effectiveness of COX-2 inhibitor drugs in treatment of RCC patients.

Prognostic value of CD44 expression in renal cell carcinoma: a systematic review and meta-analysis

CD44 is a marker of cancer stem-like cells in renal cell carcinoma (RCC). However, the prognostic value of CD44 in RCC remains controversial. This study evaluated the correlation of CD44 expression with the clinicopathological features of RCC through a meta-analysis. We systematically searched PubMed, ISI Web of Science and Embase for relevant studies until February 2015. We collected and analysed data on clinical stage, Fuhrman grade, microvascular invasion, recurrence, five-year overall survival (OS), disease-specific survival (DSS) and disease-free survival (DFS). Twenty studies involving 1672 patients satisfied the inclusion criteria. Results showed that high CD44 expression in RCC was a poor prognostic marker for five-year OS (RR = 0.69, 95% CI 0.60–0.78) in a fixed-effects model and for five-year DSS (RR = 0.46, 95% CI 0.27–0.80) and five-year DFS (RR = 0.63, 95% CI 0.43–0.93) in a random-effects model. CD44 expression also correlated with Furhman grade (RR = 0.61, 95% CI 0.48–0.77), tumour recurrence (RR = 7.42, 95% CI 3.74–14.70) and MVI (Microvascular invasion) (RR = 3.63, 95% CI 1.97–6.71). This meta-analysis suggests that CD44 is a prognostic marker in RCC. High CD44 expression correlates with high Fuhrman grade, recurrence, MVI and poor prognosis.

Biology of renal tumour cancer stem cells applied in medicine

The present article highlights the diverse role of stem cells in normal kidney and renal cancer, with special emphasis on surface markers. Proteins such as CD105 and CD133 have been reported as being significant in clear cell renal cell carcinoma (ccRCC) cancer stem cells. The role of normal kidney progenitor cells and their surface markers is compared with the role of those surface markers in ccRCC. Subsequently, we state the current hypothesis about origin of tumour-initiating cells along with their clinical and prognostic potential in RCC. Finally, we present future perspectives with respect to recent studies.

CD44v3 and VEGF-C expression and its relationship with lymph node metastasis in squamous cell carcinomas of the uterine cervix

BACKGROUND

To investigate the expression of CD44v3 and vascular endothelial growth factor-C (VEGF-C) and their relationship with lymph node metastasis in squamous cell carcinomas (SCC) of the uterine cervix.

MATERIALS AND METHODS

Expression of CD44v3 and VEGF-C was analyzed in 109 cases of cervical SCC by immunohistochemistry (IHC). The relationship was analyzed between expression and the patient age, histological differentiation, formation of tumor emboli in lymphoid vessels, lymph node metastasis, FIGO staging, and TNM classification.

RESULTS

Expression rates for both CD44v3 and VEGF-C were 43.1% in cervical SCC. The cells with positive immunohistochemical staining of CD44v3 were distributed mainly around the keratin pearls in well differentiated carcinomas, but distributed diffusely in the moderately and poorly differentiated lesions. VEGF-C was found stained positively in most of the tumor cells. There were differences in expression between normal epithelium and atypical hyperplasia as well as carcinoma. Both CD44v3 and VEGF-C were found to be associated positively with lymph node metastasis and TNM classification (both p=0.000). Neither CD44v3 nor VEGF-C was found to be associated with patient age, histological differentiation, formation of tumor emboli in lymphoid vessels and FIGO staging. CD44v3 was found to be associated with VEGF-C positively (p=0.000).

CONCLUSIONS

Abnormal expression of CD44v3 and VEGF-C is associated closely with the lymph node metastasis in cervical SCC, and these agents may cooperate in carcinogenesis and development of metastatic lesions.

miRNA-34a suppresses cell proliferation and metastasis by targeting CD44 in human renal carcinoma cells

PURPOSE

We investigated the potential functions of miR-34a in CD44 transcriptional complexes in renal cell carcinoma.

MATERIALS AND METHODS

We detected miR-34a expression by quantitative real-time polymerase chain reaction. Oligonucleotides were used to over express miR-34a. Cell proliferation and xenograft assays, colony formation and flow cytometry were done to examine effects on cancer cell proliferation in vitro and in vivo. Luciferase assay was performed to verify the precise target of miR-34a.

RESULTS

Promoter methylation contributed to miR-34a loss in the ACHN, 786-O and SN12PM6 renal carcinoma cell lines. Ectopic over expression of miR-34a restrained cell growth, tube formation and migration/invasion, and significantly suppressed the growth of renal carcinoma xenografts and metastasis in nude mice. Dual luciferase assay revealed that CD44 was a direct target of miR-34a in renal cancer cells and CD44 knockdown by RNAi in renal cancer cells suppressed tumor progression. In contrast, CD44 ectopic expression partially reversed the antitumor effects of miR-34a in renal cancer cells.

CONCLUSIONS

Our findings indicate that miR-34a targets CD44 in renal cancer cells and suppresses renal cancer cell growth, tube formation and metastasis in vitro and in vivo. Thus, miR-34a may be a potential molecular target for novel therapeutic strategies for clear cell renal carcinoma.

Analyses of potential predictive markers and survival data for a response to sunitinib in patients with metastatic renal cell carcinoma

BACKGROUND

Patients with metastatic clear cell renal cell carcinoma (ccRCC) are frequently treated with tyrosine kinase inhibitors (TKI) such as sunitinib. It inhibits angiogenic pathways by mainly targeting the receptors of VEGF and PDGF. In ccRCC, angiogenesis is characterized by the inactivation of the von Hippel-Lindau gene (VHL) which in turn leads to the induction of HIF1α target genes such as CA9 and VEGF. Furthermore, the angiogenic phenotype of ccRCC is also reflected by endothelial markers (CD31, CD34) or other tumor-promoting factors like Ki67 or survivin.

METHODS

Tissue microarrays from primary tumor specimens of 42 patients with metastatic ccRCC under sunitinib therapy were immunohistochemically stained for selected markers related to angiogenesis. The prognostic and predictive potential of theses markers was assessed on the basis of the objective response rate which was evaluated according to the RECIST criteria after 3, 6, 9 months and after last report (12-54 months) of sunitinib treatment. Additionally, VHL copy number and mutation analyses were performed on DNA from cryo-preserved tumor tissues of 20 ccRCC patients.

RESULTS

Immunostaining of HIF-1α, CA9, Ki67, CD31, pVEGFR1, VEGFR1 and -2, pPDGFRα and -β was significantly associated with the sunitinib response after 6 and 9 months as well as last report under therapy. Furthermore, HIF-1α, CA9, CD34, VEGFR1 and -3 and PDGRFα showed significant associations with progression-free survival (PFS) and overall survival (OS). In multivariate Cox proportional hazards regression analyses high CA9 membrane staining and a response after 9 months were independent prognostic factors for longer OS. Frequently observed copy number loss and mutation of VHL gene lead to altered expression of VHL, HIF-1α, CA9, and VEGF.

CONCLUSIONS

Immunoexpression of HIF-1α, CA9, Ki67, CD31, pVEGFR1, VEGFR1 and -2, pPDGFRα and -β in the primary tumors of metastatic ccRCC patients might support the prediction of a good response to sunitinib treatment.

Immunohistochemical expression of CD44s in renal cell carcinoma lacks independent prognostic significance

PURPOSE

To analyze the immunohistochemical expression of the standard isoform of CD44 (CD44s) adhesion molecule in clear cell renal cell carcinoma (CCRCC) and its impact on clinical outcomes.

MATERIALS AND METHODS

Ninety-nine consecutive patients treated surgically for RCC between 1992 and 2009 were selected. A single pathologist reviewed all cases to effect a uniform reclassification and determine the most representative tumor areas for construction of a tissue microarray. The same pathologist, who was blinded to the outcome of the cases, semi-quantitatively scored the staining intensity of CD44s in all specimens. The counting was done using the H-Score algorithm.

RESULTS

Of the 99 immunostained RCC specimens, 57(57.7 %) showed low expression, and 42(42.4 %) showed high expression levels of CD44s. The expression of CD44s was directly associated with tumor size (p = 0.03), clinical stage (p = 0.02) and Fuhrman grade (p = 0.02). Disease specifi c survival (DSS) rates for patients whose specimens expressed low and high levels of CD44s was 88.1 % and 67.5 %, respectively (p = 0.009). Progression free survival (PFS) rates in patients with low and high expression of CD44s were 78.8 % and 61.7 %, respectively (p = 0.05). Classical features such as the presence of metastasis and clinical stage remained isolated predictors of survival.

CONCLUSIONS

Immunohistochemical expression of CD44s was associated with important clinical variables such as stage and Fuhrman grade. However, it was not an independent predictor of survival. Therefore, we believe it has a limited role as a prognostic marker in patients with CCRCC.

Vasohibin-1 is a new predictor of disease-free survival in operated patients with renal cell carcinoma

Background

Vasohibin-1 (VASH1) is an endothelium-produced angiogenesis inhibitor. Renal cell carcinoma is highly vascularised, but the significance of endogenous VASH1 in renal cell carcinoma has not been defined.

Aims

To identify VASH1 expression and its possible relationship with various clinicopathological factors and prognosis in renal cell carcinoma.

Methods

A retrospective analysis of 122 tumours obtained from 118 consecutive patients with renal cell carcinoma was performed. The expression patterns of VASH1, CD31, vascular endothelial growth factor (VEGF) and VEGF receptor type 2 (VEGFR2) were examined immunohistochemically and their relationships with clinicopathological factors were analysed.

Results

Microvessel density, VASH1 and VEGFR2 expression were significantly higher in clear cell carcinoma than in other subtypes. The VEGF expression pattern differed significantly between clear cell carcinoma and other histological subtypes. VASH1, pT factor and TNM stage were significantly associated with disease-free survival (p=0.030, p = 0.0012 and p = 0.0018, respectively). Cox models of multivariable disease-free survival analyses indicated that VASH1 and stage are independent prognostic factors (p=0.019 and p = 0.024).

Conclusions

VASH1 expression may be useful for estimating the prognosis of renal cell carcinoma. Further studies of the role of VASH1 in renal cell carcinoma involving larger sample sizes are warranted.

CD44 is associated with tumor recurrence and is an independent poor prognostic factor for patients with localized clear cell renal cell carcinoma after nephrectomy

CD44 has been implicated in tumor development and progression in several types of cancer. CD44 expression is altered in renal cell carcinoma (RCC) and has been suggested as a useful prognostic marker, but its prognostic role in RCC remains controversial. We investigated the expression of CD44 in a large homogeneous set of localized clear cell RCC to determine its potential prognostic value. We examined 110 patients with localized clear cell RCC who underwent nephrectomy. The clinicopathological data were obtained retrospectively and the expression level of CD44 was studied by immunohistochemistry. Correlations between CD44 expression and clinical parameters as well as survival were determined. The CD44-high expression group (HEG) was significantly associated with a higher nuclear grade (P=0.014) and tumor recurrence (P<0.001) when compared with the CD44-low expression group (LEG). Concerning survival, the 5-year recurrence-free survival (RFS) rates for the CD44-HEG and CD44-LEG groups were 38.9 and 91.3%, respectively (P<0.001), and the 5-year disease-specific survival (DSS) rates for the CD44-HEG and CD44-LEG groups were 55.6 and 94.6%, respectively (P<0.001). Multivariate analyses showed that CD44 expression [hazard ratio (HR), 9.204; P<0.001] was an independent risk factor predicting RFS in patients with clear cell RCC. CD44 expression remained an independent prognostic factor for DSS (P=0.002). In conclusion, these data indicate that CD44 expression is associated with the progression of clear cell RCC and is an independent poor prognostic factor for tumor recurrence and survival, suggesting that CD44 may serve as a useful molecular marker.

Tyrosine kinase expression profile in clear cell renal cell carcinoma

PURPOSE

To profile different tyrosine kinase (TK) expression patterns in clear cell renal carcinoma (ccRCC).

METHODS

We analysed mRNA expression levels of 89 receptor and non-receptor TK in corresponding cancer and normal renal tissue from 5 patients with ccRCC using the TaqMan Low-Density Array technology. In order to confirm aberrant TK expressions, a subsequent analysis of 25 ccRCC and corresponding normal renal tissues was performed, applying quantitative real-time PCR. To confirm mRNA expression levels on protein level, we studied ERBB4 and HCK using immunohistochemistry.

RESULTS

A total of 12 TK were significantly upregulated in ccRCC (ABL2, FLT1, BTK, HCK, JAK3, CSF1R, MET, JAK1, MATK, PTPRC, FYN and CSK), coherently 7 TK demonstrated a down-regulation (ERBB4, PDGFRA, NRTK3, SYK, ERBB2, FGFR3 and PTK7). These findings were validated by the utilization of RT-PCR for ABL2, FLT1 BTK, HCK, JAK3, CSF1R, MET, JAK1, MATK and vice versa for ERBB4 and PDGFRA. Immunohistochemistry revealed ERBB4 expression to be significantly lower in ccRCC in comparison to papillary RCC, chromophobe RCC, renal oncocytoma and normal renal tissue (P < 0.001). HCK protein expression was reduced in ccRCC in contrast to papillary RCC (P < 0.001) or oncocytoma (P = 0.023), but similar to chromphobe RCC (P = 0.470), sarcomatoid RCC (P = 0.754) and normal renal tissue (P = 0.083). Neither ERBB4 nor HCK were correlated (P > 0.05) with clinical-pathological parameters.

CONCLUSION

TK constitute valuable targets for pharmaceutical anti-cancer therapy. ERBB4 and HCK depict significantly lower expression levels in renal cancer tissues.

Molecular characterization of kidney cancer: association of hyaluronic acid family with histological subtypes and metastasis

BACKGROUND

Molecular profiling of renal cell carcinomas (RCCs) may improve the distinction between oncocytoma and malignant RCC subtypes and aid in early detection of metastasis. The hyaluronic acid (HA) family includes HA synthases (HAS1, HAS2, HAS3), hyaluronidases (HYAL-1, HYAL-2, HYAL-3, HYAL-4, PH20, HYAL-P1), and HA receptors (CD44s, CD44v, RHAMM). HA family members promote tumor growth and metastasis. The authors evaluated the expression of HA family members in kidney specimens.

METHODS

By using quantitative polymerase chain reaction, mRNA levels of 12 HA family members were measured in tumor specimens obtained from 86 consecutive patients undergoing nephrectomy; 80 of them also provided normal specimens. Mean and median follow-up were 15.2 ± 8.8 and 13.8 months. RCC specimens included clear cell RCC: 65; papillary: 10; chromophobe: 5; oncocytoma: 6; metastasis positive: 17.

RESULTS

Median HAS1, CD44s, and RHAMM transcript levels were elevated 3- to 25-fold in clear cell RCC and papillary and chromophobe tumors when compared with normal tissues. HYAL-4, CD44s, and RHAMM levels were elevated 4- to 12-fold in clear cell RCC and papillary tumors when compared with oncocytomas; only HYAL-4 levels distinguished between chromophobe and oncocytoma (P = .009). CD44s and RHAMM levels were significantly higher in tumors <4 cm (510 ± 611 and 19.6 ± 20.8, respectively) when compared with oncocytoma (46.4 ± 20 and 3.8 ± 2.5; P ≤ .006). In univariate and multivariate analyses, CD44s (P < .0001), RHAMM (P < .0001), stage, tumor size, and/or renal vein involvement were significantly associated with metastasis. The combined CD44s + RHAMM marker had 82% sensitivity and 86% specificity to predict metastasis.

CONCLUSIONS

CD44s and RHAMM levels distinguish between oncocytoma and RCC subtypes regardless of tumor size and are potential predictors of RCC metastasis.

Prostaglandin E2 regulates renal cell carcinoma invasion through the EP4 receptor-Rap GTPase signal transduction pathway

Prognosis for patients with early stage kidney cancer has improved, but the treatment options for patients with locally advanced disease and metastasis remain few. Understanding the molecular mechanisms that regulate invasion and metastasis is critical for developing successful therapies to treat these patients. Proinflammatory prostaglandin E(2) plays an important role in cancer initiation and progression via activation of cognate EP receptors that belong to the superfamily of G protein-coupled receptors. Here we report that prostaglandin E(2) promotes renal cancer cell invasion through a signal transduction pathway that encompasses EP4 and small GTPase Rap. Inactivation of Rap signaling with Rap1GAP, like inhibition of EP4 signaling with ligand antagonist or knockdown with shRNA, reduces the kidney cancer cell invasion. Human kidney cells evidence increased EP4 and decreased Rap1GAP expression levels in the malignant compared with benign samples. These results support the idea that targeted inhibition of EP4 signaling and restoration of Rap1GAP expression constitute a new strategy to control kidney cancer progression.

Concomitant renal cell carcinoma and chronic myelogenous leukemia: use of a targeted approach

Numerous therapeutic options have been introduced for metastatic renal cell carcinoma (MRCC) in recent years, including monoclonal antibodies such as bevacizumab and small-molecule tyrosine kinase inhibitors such as sunitinib and sorafenib. Similarly, several other small-molecule inhibitors-including imatinib, dasatinib, and nilotinib-have been approved for the treatment of chronic myelogenous leukemia (CML). The combination of these targeted agents is an area of intense clinical investigation. Here, we describe a patient diagnosed with MRCC)while on imatinib therapy for cml. Treatment of this patient with the combination of bevacizumab and imatinib led to a 6-month period of stable disease, with no treatment-related adverse events. More extensive clinical exploration of this combination of agents may therefore be warranted.

Transcriptional activation of the Axl and PDGFR-α by c-Met through a ras- and Src-independent mechanism in human bladder cancer

BACKGROUND

A cross-talk between different receptor tyrosine kinases (RTKs) plays an important role in the pathogenesis of human cancers.

METHODS

Both NIH-Met5 and T24-Met3 cell lines harboring an inducible human c-Met gene were established. C-Met-related RTKs were screened by RTK microarray analysis. The cross-talk of RTKs was demonstrated by Western blotting and confirmed by small interfering RNA (siRNA) silencing, followed by elucidation of the underlying mechanism. The impact of this cross-talk on biological function was demonstrated by Trans-well migration assay. Finally, the potential clinical importance was examined in a cohort of 65 cases of locally advanced and metastatic bladder cancer patients.

RESULTS

A positive association of Axl or platelet-derived growth factor receptor-alpha (PDGFR-α) with c-Met expression was demonstrated at translational level, and confirmed by specific siRNA knock-down. The transactivation of c-Met on Axl or PDGFR-α in vitro was through a ras- and Src-independent activation of mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK) pathway. In human bladder cancer, co-expression of these RTKs was associated with poor patient survival (p < 0.05), and overexpression of c-Met/Axl/PDGFR-α or c-Met alone showed the most significant correlation with poor survival (p < 0.01).

CONCLUSIONS

In addition to c-Met, the cross-talk with Axl and/or PDGFR-α also contributes to the progression of human bladder cancer. Evaluation of Axl and PDGFR-α expression status may identify a subset of c-Met-positive bladder cancer patients who may require co-targeting therapy.

Prognostic prediction in patients with metastatic renal cell carcinoma treated with sorafenib based on expression levels of potential molecular markers in radical nephrectomy specimens

OBJECTIVES

To investigate the expression levels of multiple molecular markers in radical nephrectomy specimens from patients with metastatic renal cell carcinoma (RCC) treated with sorafenib in order to identify factors predicting susceptibility to this agent.

MATERIALS AND METHODS

This study included 45 consecutive patients undergoing radical nephrectomy for clear cell RCC who were diagnosed as having metastatic diseases refractory to cytokine therapy and subsequently treated with sorafenib. Expression levels of 19 molecular markers involved in the regulation of apoptosis, cell cycle, signal transduction, and angiogenesis in primary RCC specimens were measured by immunohistochemical staining.

RESULTS

There was no molecular marker having significant impact on the prediction of response to sorafenib. However, progression-free survival (PFS) was significantly associated with the expression levels of Bcl-xL and platelet-derived growth factor receptor (PDGFR)-α in addition to the presence of bone metastasis and C-reactive protein level on univariate analysis. Of these significant factors, PDGFR-α expression and the presence of bone metastasis appeared to be independently related to PFS by multivariate analysis. Furthermore, there were significant differences in PFS according to positive numbers of these 2 independent risk factors; that is, disease progression occurred in 2 of 7 patients who were negative for risk factor, 19 of 34 positive for a single risk factor, and 6 of 6 positive for both risk factors.

CONCLUSIONS

Collectively, these findings suggest that it would be useful to consider expression levels of potential molecular markers, particularly PDGFR-α, as well as clinical parameters to select metastatic RCC patients likely to benefit from treatment with sorafenib.

In search of a better crystal ball: recent advances in prognostic markers for clear-cell renal cell carcinoma

Advances in imaging have led to a steady increase in the incidence of kidney cancer over the last two decades. There has been no corresponding improvement in our ability to predict the behavior of renal cell carcinoma. Patients with low-risk renal cell carcinoma have good long-term survival with only localized therapy but patients with aggressive disease do poorly, even with optimal multimodal treatment. Biomarkers to differentiate between these two very divergent populations have traditionally been of only limited utility. We review the recent advances in the development of molecular and immunologic markers aimed at improving prognostication of renal cell carcinoma.

Sunitinib acts primarily on tumor endothelium rather than tumor cells to inhibit the growth of renal cell carcinoma

Sunitinib is a broad-spectrum small-molecule inhibitor of receptor tyrosine kinases (RTK) that serves as the present standard of care for first-line therapy of advanced clear cell renal cell carcinoma (ccRCC). A full understanding of the targets and mechanism of action of sunitinib in ccRCC treatment remains incomplete. In this study, we evaluated several tumor cell and endothelial targets of sunitinib and investigated which RTK(s) may specifically contribute to its therapeutic effects. Microarray expression profiling and Western blot analysis revealed that among known sunitinib targets, only platelet-derived growth factor receptor-beta and vascular endothelial growth factor receptor-2 (VEGFR-2) were overexpressed in ccRCCs relative to normal tissues. Sunitinib was unable to inhibit survival or proliferation of ccRCC cells at pharmacologically relevant concentrations (approximately 0.1 micromol/L) that inhibit RTK targets. In contrast, sunitinib inhibited endothelial cell proliferation and motility at the same concentrations by suppressing VEGFR-2 signaling. Moreover, whereas sunitinib inhibited the growth of ccRCC xenograft tumors and decreased tumor microvessel density as soon as 12 hours after treatment, sunitinib showed no significant effects on tumor cell proliferation or apoptosis up to 72 hours after treatment. Our findings indicate that sunitinib inhibits ccRCC growth primarily through an antiangiogenic mechanism and not through direct targeting of ccRCC tumor cells.

mTOR in renal cell cancer: modulator of tumor biology and therapeutic target

Elucidation of the crucial role of the PI3K/Akt/mTOR pathway in the pathogenesis of cancer has led to the development of various drugs targeting this signaling cascade at distinct levels. mTOR, a serine/threonine kinase plays a pivotal role in coupling growth stimuli to cell cycle progression. There are two distinct macromolecular complexes of mTOR: mTORC1, which is rapamycin-sensitive and contains raptor; and mTORC2, which is rapamycin-insensitive and contains rictor. However, in recent preclinical studies a sustained exposure of cancer cells to rapamycin has been shown to inhibit the function of both mTORC1 and mTORC2 complexes. Downstream targets of these complexes, which involve HIF-1alpha and HIF-2alpha, cyclin D1 and PKC-alpha, are responsible for the activation of various intracellular processes leading to the activation of cell proliferation, and induction of angiogenesis, metastasis or chemoresistance. Since the biology of renal cell cancer (RCC) is tightly controlled by mTOR, targeted inhibition of mTOR function appeared to be a promising therapeutic approach for RCC patients. To date, results of two, large, Phase III clinical trials evaluating the efficacy of rapamycin derivatives (i.e., temsirolimus and everolimus) in the treatment of RCC have been published. First-line temsirolimus (CCI-779) administered to metastatic, poor-prognosis RCC patients significantly prolonged overall and progression-free survival when compared with IFN-alpha. Treatment of metastatic RCC patients refractory to tyrosine kinase inhibitors with everolimus (RAD-001) significantly prolonged progression-free survival when compared with placebo. Therapeutic strategies based on mTOR inhibition in RCC demonstrated a significant clinical activity. However, there are still patients refractory to mTOR inhibitors. Various molecular mechanisms of resistance to rapalogues have been identified and will have to be targeted simultaneously with mTOR in order to achieve a complete inhibition of signaling pathways crucial for the pathogenesis of RCC. Such clinical trials evaluating a combination of mTOR inhibitors with other targeted therapies are ongoing.

Hyaluronan and hyaluronidase in genitourinary tumors

Genitourinary cancers are the most frequently diagnosed cancers in men and the fifth most common in women. Management of disease through accurate and cost effective early diagnostic markers, as well as identification of valid prognostic indicators, has contributed significantly to improved treatment outcomes. In this review, we will discuss the function, regulation and clinical utility of hyaluronan (HA), genes encoding its metabolic enzymes and receptors that mediate its cellular effects. Specific HA synthase (HAS) and hyaluronidase (HAase) genes encode the enzymes that produce HA polymers and oligosaccharides, respectively. Differential effects of these enzymes in progression of genitourinary tumors are determined by the relative balance between HAS and HAase levels, as well as the distribution of receptors. The genes are regulated in a complex fashion at the transcriptional and post-translational levels, but also by epigenetic events, alternative mRNA splicing, and subcellular localization. Importantly, the major tumor-derived HAase enzyme, HYAL-1, either alone or together with HA, is an accurate diagnostic and prognostic marker for genitourinary tumors.

Prognostic markers in renal cell carcinoma

PURPOSE OF REVIEW

This article reviews recent reports on prognostic markers in renal cell carcinoma.

RECENT FINDINGS

Inclusion in studies of larger cohorts of patients has yielded enhanced prognostic information from integrated pathological markers; the findings suggest that adjustment to the TNM (tumour-node-metastasis) system is warranted. A number of patient-related factors remain important prognostically, including performance status, C-reactive protein and thrombocytosis, but also immunological factors (e.g. expression of B7-H1 by renal cell carcinomas is associated with progression). Additional prognostic information may be derived from a range of molecular markers. Findings of gene array and methylation studies may yield independent prognostic information. Enhanced knowledge of signalling pathways has facilitated better understanding of underlying biology and prediction of response to treatment. Other genes involved in regulating hypoxia-inducible factor [e.g. genes encoding carbonic anhydrase-IX and PTEN (phosphatase and tensin homolog)] were reported to be prognostically important in renal cell carcinoma. Other markers independently predicted survival (e.g. thymidine-phosphorylase and survivin).

SUMMARY

The potential of molecular markers suggested by clinical research is encouraging. Knowledge of various pathways will facilitate creation of systems of biomarkers that are predictive of individual response to therapy. Useful biomarkers may have potential as therapeutic targets.