Overexpression of KIT in chromophobe renal cell carcinoma

Targeted therapies for non-clear renal cell carcinoma

The treatment of advanced and metastatic kidney cancer has been revolutionized by the development of targeted systemic therapies. Despite the growing number of available agents approved for use against clear cell renal cell carcinoma, patients with non-clear histologies, constituting approximately 1 in 4 cases of kidney cancer, have not received the same attention. The majority of clinical trials testing novel targeted therapies have excluded non-clear subtypes, providing limited therapeutic options for patients with these diagnoses and their oncologists. This review will focus on the use of targeted therapies against the non-clear histologic subtypes of renal cell carcinoma: papillary I and II, chromophobe, and collecting duct. The unique genetic and molecular profiles of each distinct non-clear kidney cancer subtype will be described, as these differences are integral to the development and effectiveness of the novel agents used to treat them. Trials focusing on non-clear kidney cancer, or those that treated clear cell tumors along with significant numbers of non-clear subtypes, will be discussed. The role of cytoreductive nephrectomy and the use of neoadjuvant and adjuvant targeted therapy will be reviewed. Lastly, areas of future research will be highlighted.

Insulin-like growth factor binding protein-3 gene methylation and protein expression in gastric adenocarcinoma

OBJECTIVE

The aim of this study was to evaluate IGFBP-3 protein expression, its correlation with gene promoter methylation pattern in gastric carcinogenesis and with clinicopathological characteristics.

DESIGN

Forty-three normal gastric mucosa and 94 adenocarcinoma samples were investigated through methylation specific PCR, after bisulfite modification. Immunohistochemistry was analyzed using peroxidase in 54 gastric cancer and 20 normal gastric mucosa samples.

RESULTS

IGFBP-3 expression was higher in tumor samples than in normal mucosa (p<0.0001). Intestinal type presented a higher frequency of protein expression than diffuse type (p=0.0412). Methylation frequency of IGFBP-3 promoter in gastric samples revealed, respectively, 95.7% and 97.7% in neoplastic and non-neoplastic samples. The frequency of IGFBP-3 methylation did not differ between tumor and normal samples (95.7% versus 97.7%, p=0.7810). We did not observe a significant correlation between IGFBP-3 promoter methylation and protein expression.

CONCLUSION

In summary, our study did not observe any influence of IGFBP-3 promoter methylation on protein expression. Moreover we propose that IGFBP-3 immunostaining in gastric tissue may be a useful marker for malignancy.

Identifying mRNA targets of microRNA dysregulated in cancer: with application to clear cell Renal Cell Carcinoma

BACKGROUND

MicroRNA regulate mRNA levels in a tissue specific way, either by inducing degradation of the transcript or by inhibiting translation or transcription. Putative mRNA targets of microRNA identified from seed sequence matches are available in many databases. However, such matches have a high false positive rate and cannot identify tissue specificity of regulation.

RESULTS

We describe a simple method to identify direct mRNA targets of microRNA dysregulated in cancers from expression level measurements in patient matched tumor/normal samples. The word "direct" is used here in a strict sense to: a) represent mRNA which have an exact seed sequence match to the microRNA in their 3'UTR, b) the seed sequence match is strictly conserved across mouse, human, rat and dog genomes, c) the mRNA and microRNA expression levels can distinguish tumor from normal with high significance and d) the microRNA/mRNA expression levels are strongly and significantly anti-correlated in tumor and/or normal samples. We apply and validate the method using clear cell Renal Cell Carcinoma (ccRCC) and matched normal kidney samples, limiting our analysis to mRNA targets which undergo degradation of the mRNA transcript because of a perfect seed sequence match. Dysregulated microRNA and mRNA are first identified by comparing their expression levels in tumor vs normal samples. Putative dysregulated microRNA/mRNA pairs are identified from these using seed sequence matches, requiring that the seed sequence be conserved in human/dog/rat/mouse genomes. These are further pruned by requiring a strong anti-correlation signature in tumor and/or normal samples. The method revealed many new regulations in ccRCC. For instance, loss of miR-149, miR-200c and mir-141 causes gain of function of oncogenes (KCNMA1, LOX), VEGFA and SEMA6A respectively and increased levels of miR-142-3p, miR-185, mir-34a, miR-224, miR-21 cause loss of function of tumor suppressors LRRC2, PTPN13, SFRP1, ERBB4, and (SLC12A1, TCF21) respectively. We also found strong anti-correlation between VEGFA and the miR-200 family of microRNA: miR-200a*, 200b, 200c and miR-141. Several identified microRNA/mRNA pairs were validated on an independent set of matched ccRCC/normal samples. The regulation of SEMA6A by miR-141 was verified by a transfection assay.

CONCLUSIONS

We describe a simple and reliable method to identify direct gene targets of microRNA in any cancer. The constraints we impose (strong dysregulation signature for microRNA and mRNA levels between tumor/normal samples, evolutionary conservation of seed sequence and strong anti-correlation of expression levels) remove spurious matches and identify a subset of robust, tissue specific, functional mRNA targets of dysregulated microRNA.

Kinase targets in renal-cell carcinomas: reassessing the old and discovering the new

Renal-cell carcinoma is a heterogeneous group of tumours that arise in the adult kidneys. Irrespective of the type of renal tumour, traditional chemotherapeutic and radiation-based therapies have been largely ineffective at treating advanced tumours, with long-term survival being very low. Molecularly-targeted inhibitors of protein kinases are effective in delaying progression of advanced renal tumours. These therapies revolve around inhibition of the vascular endothelial growth factor receptor tyrosine kinase and the mammalian target of rapamycin serine or threonine kinase signalling pathways. The genetic complexity of renal tumours revealed by gene-expression profiling and other molecular-genetic technologies indicate that inhibition of additional kinase-associated pathways could also prevent renal tumour growth. In this review, we discuss the use of molecularly-targeted kinase inhibitors in the treatment of renal-cell carcinoma and identify the next generation of kinase inhibitors that show promise for treatment.

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.

Renal cell carcinoma

Renal Cell Carcinoma (RCC) has the highest mortality rate of the genitourinary cancers and the incidence of RCC has risen steadily. If detected early, RCC is curable by surgery although a minority are at risk of recurrence. Increasing incidental detection and an ageing population has led to active surveillance as an option for patients with small renal masses. RCC is heterogeneous and comprises several histological cell types with different genetics, biology and behavior. The identification of the genes predisposing to inherited syndromes with RCC has provided much of our knowledge of the molecular basis of early sporadic RCC. Many of the oncogenes and tumor suppressor genes that are mutated leading to pathway dysregulation in RCC remain to be elucidated. Global studies of copy number, gene sequencing, gene expression, miRNA expression and gene methylation in primary RCC will lead towards this goal. The natural history of RCC indicated by candidate precursor lesions, multifocal or bilateral disease, growth rate of small renal masses under surveillance, and high risk populations provide insight into the behavior of this disease. The use of molecular markers for early detection and prognosis merits more attention with ongoing advances in omics technologies. This review focuses on early RCC, that is disease confined within the renal capsule.

Chromophobe renal cell cancer--review of the literature and potential methods of treating metastatic disease

Chromophobe renal cell carcinoma (ChRCC) is a subtype of renal cell carcinoma (RCC). ChRCC is diagnosed mainly in 6th decade of life. An incidence of ChRCC is similar in both men and woman. Eighty six percent of ChRCCs cases are diagnosed in stage 1 or 2. Prognosis of ChRCC is better than in other types of RCC. Five- and 10-year disease free survival (DFS) for ChRCC was 83.9% and 77.9%, respectively. Expression of immunohistological markers: cytokeratins (CK), vimentin, epithelial membrane antigen (EMA), CD10 could be potentially helpful in diagnosis of different subtypes of RCC. From all conventional RCC, CD 117 was detected (overexpression) in membrane of cells ChRCC.Overexpression of CD117 on cellular membranes of ChRCC could be a potential target for kinase inhibitors like: imatinib, dasatinib, nilotinib. The potential targets for other kinase inhibitors (sunitinib and sorafenib) in ChRCC seem to be VEGFR and PDGFR. On the basis for formulating research hypotheses which should be verified by prospective studies.

Systematic comparative protein expression profiling of clear cell renal cell carcinoma: a pilot study based on the separation of tissue specimens by two-dimensional gel electrophoresis

Proteome-based technologies represent powerful tools for the analysis of protein expression profiles, including the identification of potential cancer candidate biomarkers. Thus, here we provide a comprehensive protein expression map for clear cell renal cell carcinoma established by systematic comparative two-dimensional gel electrophoresis-based protein expression profiling of 16 paired tissue systems comprising clear cell renal cell carcinoma lesions and corresponding tumor-adjacent renal epithelium using overlapping narrow pH gradients. This approach led to the mapping of 348 distinct spots corresponding to 248 different protein identities. By implementing restriction criteria concerning their detection frequency and overall regulation mode, 28 up- and 56 down-regulated single target spots were considered as potential candidate biomarkers. Based on their gene ontology information, these differentially expressed proteins were classified into distinct functional groups and according to their cellular distribution. Moreover, three representative members of this group, namely calbindin, gelsolin, and heart fatty acid-binding protein, were selected, and their expression pattern was analyzed by immunohistochemistry using tissue microarrays. Thus, this pilot study provides a significant update of the current renal cell carcinoma map and defines a number of differentially expressed proteins, but both their potential as candidate biomarkers and clinical relevance has to be further explored in tissues and for body fluids like serum and urine.

Potentiation of growth factor signaling by insulin-like growth factor-binding protein-3 in breast epithelial cells requires sphingosine kinase activity

We have investigated the mechanism underlying potentiation of epidermal growth factor receptor (EGFR) and type 1 insulin-like growth factor receptor (IGFR1) signaling by IGF-binding protein-3 (IGFBP-3) in MCF-10A breast epithelial cells, focusing on a possible involvement of the sphingosine kinase (SphK) system. IGFBP-3 potentiated EGF-stimulated EGF receptor activation and DNA synthesis, and this was blocked by inhibitors of SphK activity or small interference RNA-mediated silencing of SphK1, but not SphK2, expression. Similarly, IGFR1 phosphorylation and DNA synthesis stimulated by LR3-IGF-I (an IGF-I analog not bound by IGFBP-3), were enhanced by IGFBP-3, and this was blocked by SphK1 silencing. SphK1 expression and activity were stimulated by IGFBP-3 approximately 2-fold over 24 h. Silencing of sphingosine 1-phosphate receptor 1 (S1P1) or S1P3, but not S1P2, abolished the effect of IGFBP-3 on EGF-stimulated EGFR activation. The effects of IGFBP-3 could be reproduced with exogenous S1P or medium conditioned by cells treated with IGFBP-3, and this was also blocked by inhibition of S1P1 and S1P3. These data indicate that potentiation of growth factor signaling by IGFBP-3 in MCF-10A cells requires SphK1 activity and S1P1/S1P3, suggesting that S1P, the product of SphK activity and ligand for S1P1 and S1P3, is the "missing link" mediating IGF and EGFR transactivation and cell growth stimulation by IGFBP-3.

Molecular Pathology of the Genitourinary Tract: Molecular Pathology of Kidney and Testes

With the advent of newer molecular technologies, our knowledge of cellular mechanisms with tumors of the kidney and testis has grown exponentially. Molecular technologies have led to better understanding of interplay between the von Hippel-Lindau gene and angiogenic cytokines in renal cancer and isochromosome 12p in testicular neoplasms. The result has been development of antiangiogenic-targeted therapy within recent years that has become the mainstay treatment for metastatic renal cell cancer. In the near future, classification and diagnosis of renal and testicular tumors through morphologic analysis will be supplemented by molecular information correlating to prognosis and targeted therapy. This article outlines tumor molecular pathology of the kidney and testis encompassing current genomic, epigenomic, and proteonomic findings.

Diagnostic and prognostic molecular markers for renal cell carcinoma: a critical appraisal of the current state of research and clinical applicability

CONTEXT

Earlier detection of renal cell carcinoma (RCC) and the recent expansion of treatment possibilities have positively influenced the outlook for patients with this disease. However, progression and treatment response are still not sufficiently predictable. Molecular markers could help to refine individual risk stratification and treatment planning, although they have not yet become clinically routine.

OBJECTIVE

This review presents an overview of diagnostic and prognostic molecular markers for RCC and a subgrouping of these markers for different clinical issues.

EVIDENCE ACQUISITION

Literature and recent meeting abstracts were searched using these terms: renal (cell) carcinoma, molecular/tumor markers, biopsy, blood, urine, disease progression/prognosis, immunohistochemistry, risk factors, and survival. Due to the resulting large number of articles, studies were subjectively selected according to the importance of a study on the field, number of investigated patients, originality, multivariate analyses performed, contrast with previously published data, actuality, and assumed clinical applicability of the described results. More then 90% of the selected studies originated from the past 10 yr; >50% of the articles were written in 2006 or later.

EVIDENCE SYNTHESIS

These data were predominantly obtained via nonrandomized, retrospective, but often controlled studies. Thereby, the resulting level of evidence is 2A/2B. The broad spectrum of described molecular markers (MMs) for RCC consists of markers already extensively studied in other malignancies (eg, p53), as well as MMs typically associated with specific RCC-altered gene functions and pathways (eg, von Hippel-Lindau [VHL]). The main goal of using MMs is to refine the prediction of clinical end points like tumor progression, treatment response, and cancer-specific and/or overall survival. Further, MMs might facilitate the clinical work-up of undefined renal masses and prove to be more convenient tools for screening and follow-up in blood and urine.

CONCLUSIONS

Presently, there are a number of promising MMs for diverse clinical questions, but the available data are not yet valid enough for routine, clinical application. We should comply with the demand for large multicenter prospective investigations, stratified for RCC type and treatment modalities, to lift the use of molecular markers in RCC to a practical level, thereby providing a better consultation for our patients regarding diagnosis, treatment, and follow-up.

Chromophobe renal cell carcinoma with neuroendocrine differentiation

Chromophobe renal cell carcinoma was described by Thoenes et al. in 1986, and associations with carcinoma of collecting ducts, conventional renal cell carcinoma and sarcomatoid renal cell carcinoma have been described. We report a case of chromophobe renal cell carcinoma which showed neuroendocrine differentiation. This is the first known case to be clearly identified as such. The patient was a 56-year-old man with constant right flank pain and hematuria; CT scan revealed an 8.5 cm nonhomogeneous mass involving the right kidney. Right radical nephrectomy was performed. The tumor showed a mixture of classical and eosinophilic patterns of chromophobe cell carcinoma. Additionally, it showed insular, glandular and rosetoid-like formations embedded in a dense eosinophilic hyaline stroma. The cells were cuboid or cylindrical with well-defined boundaries, finely stippled chromatin and a small nucleolus. The appearance of the cytoplasm varied from faintly eosinophilic to coarsely granular eosinophilic. Immunohistochemically, the neuroendocrine areas were reactive for C-kit, epithelial membrane antigen, cytokeratin, cytokeratin 7, chromogranin A, neuron-specific enolase, CD56 and S-100 protein. Our case represents a typical chromophobe carcinoma with neuroendocrine differentiation. Additionally, the immunohistochemical profile in both types of lesion suggests a common origin from renal tubular cells.

Differential expression in clear cell renal cell carcinoma identified by gene expression profiling

PURPOSE

Gene expression profiling has been shown to provide prognostic information on patients with solitary sporadic renal cell carcinoma. To our knowledge there is no reliable way to differentiate synchronous renal metastasis from bilateral primary tumors in patients with bilateral renal cell carcinoma. We present data using a custom kidney cancer cDNA array that can predict the outcome in patients with unilateral and bilateral renal cell carcinoma.

MATERIALS AND METHODS

Fresh frozen tissue from 38 clear cell renal cell carcinomas was analyzed using a cancer cDNA array containing 3,966 genes relevant to cancer or kidney development. Median followup was 5.3 years. Cancer recurred in 12 patients (43%) and 11 (39%) had died by the last followup.

RESULTS

Using a training data set of 8 tumors a 44 gene expression profile distinguishing aggressive and indolent clear cell renal cell carcinoma was identified. Of 29 single clear cell renal cell carcinomas 16 and 13 were predicted to be indolent and aggressive, respectively, by the gene expression profile. Recurrence-free survival at 5 years was 68% and 42% in these 2 groups, respectively (p = 0.032). Clear cell renal cell carcinoma classified as indolent or aggressive according to SSIGN (stage, size, grade and necrosis) score showed a 5-year recurrence-free survival rate of 78% and 42%, respectively (p = 0.021). On Cox proportional hazards analysis the gene expression profile was not an independent predictor of recurrence-free survival after accounting for SSIGN score. Gene expression profile classification correlated with cancer specific survival at 5 years in 4 of 4 patients with metachronous clear cell renal cell carcinoma but in only 2 of 4 with bilateral synchronous clear cell renal cell carcinoma.

CONCLUSIONS

Gene expression profiling using a kidney cancer relevant cDNA array can differentiate between aggressive and indolent clear cell renal cell carcinomas. Gene expression profile results may be most useful for unilateral clear cell renal cell carcinoma when results are discordant with predictions of tumor behavior based on standard clinicopathological features. In addition, gene expression profiling can provide prognostic information that may help characterize tumors of unknown clinical stage, such as bilateral metachronous clear cell renal cell carcinoma.

The diagnostic and prognostic utility of claudin expression in renal cell neoplasms

This study evaluated the expression patterns of claudins 1, 3, 4, 7, and 8 in human renal cell carcinomas and oncocytomas and correlated expression with patient prognosis. Tissue microarrays were created from paraffin-embedded tissue samples from 141 patients with renal cell carcinomas or oncocytoma (90 clear cell, 22 papillary, 17 chromophobe renal cell carcinomas, and 12 oncocytomas). The staining pattern for claudins 3, 4, 7, and 8 was membranous and/or cytoplasmic, whereas claudin 1 was predominantly membranous in both nonneoplastic renal tissue and tumors. Negative to weak claudin 3 staining was predominantly detected in Fuhrman's grade 1 and 2 clear cell renal cell carcinomas (78%; P=0.016), suggesting that upregulation of claudin 3 potentially occurs concomitantly with increasing grade of clear cell renal cell carcinomas. In addition, Kaplan-Meier univariate analysis showed a significant inverse correlation between moderate to strong claudin 3 and 4 expression with overall survival in clear cell renal cell carcinomas (P=0.038 and P=0.031). Moderate to strong claudin 7 expression was significantly more common in chromophobe renal cell carcinomas (94%) than in oncocytomas (55%; P=0.041). Claudin 8 staining was moderate to strong in 92% of oncocytomas, which differentiated them from papillary and clear cell renal cell carcinomas (14 and 12%; both P<0.0001). Only negative to weak claudin 8 staining was detected in all chromophobe renal cell carcinomas, whereas there were no claudin 8 negative oncocytomas and 8% exhibited a weak staining pattern (P<0.0001). Due to their distinctive expression patterns, claudins 7 and 8 can be used as useful immunohistochemical markers for the separation of chromophobe renal cell carcinomas from oncocytomas, whereas claudins 3 and 4 may serve as indicators of prognosis in clear cell renal cell carcinomas.

Collecting duct carcinoma of the kidney: an immunohistochemical evaluation of the use of antibodies for differential diagnosis

Collecting duct carcinoma is a highly aggressive renal epithelial malignancy, although it accounts for less than 1% of the incidence of renal epithelial neoplasms. Differential diagnoses between collecting duct carcinoma, pelvic urothelial carcinoma with marked invasion to the renal parenchyma (invasive urothelial carcinoma), and papillary renal cell carcinoma is often challenging. In our current study, we examined the utility of using commercially available antibodies, in conjunction with lectin histochemistry, for such differential diagnoses. We examined 17 cases of collecting duct carcinoma, 10 cases of invasive urothelial carcinoma and 15 cases of papillary renal cell carcinoma (type 1, 6 cases; type 2, 9 cases) in these evaluations. Our results indicated that Ulex europaeus agglutinin 1, E-cadherin, and c-KIT were frequently positive in collecting duct carcinoma and invasive urothelial carcinoma, in comparison with papillary renal cell carcinoma, which had negative results for CD10 and alpha-methylacyl CoA racemase. We found, however, that collecting duct carcinoma showed positivity for high-molecular-weight cytokeratin and low-molecular-weight cytokeratin at a low frequency compared with invasive urothelial carcinoma, and that these distinctions need further careful evaluation. In addition, high-molecular-weight cytokeratin positivity was not a reliable marker for collecting duct carcinoma. We conclude that Ulex europaeus agglutinin 1 reactivity and positivity for E-cadherin and c-KIT are effective in distinguishing collecting duct carcinoma from papillary renal cell carcinoma, and that negative results for alpha-methylacyl CoA racemase and CD10 are potentially useful hallmarks of this distinction also. In contrast, a differential diagnosis for collecting duct carcinoma and invasive urothelial carcinoma will require careful examination of multiple routinely stained specimens, particularly in cases of in situ neoplastic lesions in the pelvic mucosa.

Molecular diagnosis of renal cell neoplasms: the usefulness of immunohistochemistry and fluorescence in situ hybridization

BACKGROUND

The classification of renal cell neoplasms includes different subtypes of tumors characterized by different outcome. Some overlapping morphological features and the increasing recognition of new entities are making the traditional histologic distinction of renal cell neoplasms difficult and more tools improving the specificity of the correct identification are needed. Among molecular analyses, immunohistochemistry and fluorescence in situ hybridization have become the most helpful procedures, solving many issues in the differential diagnosis of the renal cell neoplasms.

OBJECTIVE

The aim of this review is to merge the large amount of recent knowledge regarding molecular markers of renal cell neoplasms into a helpful diagnostic algorithm.

CONCLUSION

It is proposed that immunoreactions for CD10, Alpha-methylacyl-CoA racemase, cytokeratin 7, parvalbumin and S100A1, and the cytogenetical analysis of chromosomes 3p, 1, 2, 6, 7, 10, 17 and Y can now offer the most specific tools for the classification of renal cell tumors.

CD117 expression in normal, neoplastic, inflammatory, and reactive lesions of the thyroid

The mutations of c-kit gene, which encodes a transmembrane receptor tyrosine kinase (CD117-KIT) or activation of CD117, lead to the activation of signal transduction cascades regulating cell proliferation, apoptosis, chemotaxis, and adhesion. The aim of this study was to investigate the expression of CD117 in normal, inflammatory, neoplastic, and reactive lesions of the thyroid. Using polyclonal anti-CD117 antibody, we performed immunohistochemical staining on tissue blocks from 230 cases obtained from the archives of the Department of Pathology, Ondokuz Mayis University (Samsun, Turkey), collected between 1990 and 2006. Each slide was evaluated for extent and intensity of staining. Staining extent was expressed as the percentage of stained cells. Staining of <10% of the cells was accepted as negative. Staining intensity was evaluated only in positive cases. By addition of the extent and intensity scores, the combined score was calculated. In our study, the combined CD117 staining scores of neoplastic and inflammatory groups were found to be higher than the reactive and normal groups. Within the neoplastic group, papillary carcinomas differed from follicular adenomas significantly, although papillary carcinomas showed no statistically significant difference compared to follicular carcinomas. Immunohistochemical CD117 positivity was detected in a wide range of neoplastic and inflammatory thyroid diseases. The neoplastic group and, within them, the papillary carcinomas showed a higher ratio of CD117 positivity. Although our results need to be confirmed by other molecular and genetic studies, the high rate of positivity in papillary carcinomas was one of the striking findings, which may result in novel diagnostic and therapeutic approaches.

Efficacy of sunitinib and sorafenib in metastatic papillary and chromophobe renal cell carcinoma

PURPOSE

Sunitinib and sorafenib are novel tyrosine kinase inhibitors (TKIs) that have shown significant clinical activity in metastatic clear cell renal cell carcinoma (RCC). The activity of sunitinib and sorafenib in non-clear cell histologies has not been evaluated.

PATIENTS AND METHODS

Clinical features at study entry and treatment outcomes were evaluated in patients with metastatic papillary RCC (PRCC) and chromophobe RCC (ChRCC) who received either sunitinib or sorafenib as their initial TKI treatment in five US and French institutions. Response rate and survival were documented. Fisher's exact test was used for categoric variables, and the Kaplan-Meier method was used to estimate survival.

RESULTS

Fifty-three patients were included. The number of patients with papillary and chromophobe histologies was 41 (77%) and 12 (23%), respectively. Response rate, progression-free survival (PFS) time, and overall survival time for the entire cohort were 10%, 8.6 months, and 19.6 months, respectively. Three (25%) of 12 ChRCC patients achieved a response (two patients treated with sorafenib and one treated with sunitinib), and PFS was 10.6 months. Two (4.8%) of 41 PRCC patients achieved a response (both patients were treated with sunitinib). PFS for the whole cohort was 7.6 months. Sunitinib-treated PRCC patients had a PFS of 11.9 months compared with 5.1 months for sorafenib-treated patients (P < .001).

CONCLUSION

Patients with PRCC and ChRCC may have prolonged PFS from sunitinib and sorafenib, although clinical responses remain overall low in PRCC. Additional prospective trials with these agents in non-clear cell RCC will further clarify their use in the future.

Renal epithelial neoplasms: diagnostic applications of gene expression profiling

Renal cell carcinoma (RCC) is the most common form of kidney cancer in adults. RCC is a significant challenge for pathologic diagnosis and clinical management. The primary approach to diagnosis is by light microscopy, using the World Health Organization (WHO) classification system, which defines histopathologic tumor subtypes with distinct clinical behavior and underlying genetic mutations. However, light microscopic diagnosis of RCC subtypes can be difficult due to variable histology, morphologic features shared by tumor subtypes, and a growing frequency of small tumor biopsies with limited morphologic information. In addition to these diagnostic problems, the clinical behavior of RCC is highly variable, and therapeutic response rates are poor. Few clinical assays are available to predict outcome in RCC or correlate behavior with histology. Therefore, novel RCC classification systems based on gene expression should be useful for diagnosis, prognosis, and treatment. Recent microarray studies have shown that renal tumors are characterized by distinct gene expression profiles, which can be used to discover novel diagnostic and prognostic biomarkers. Here, we review clinical features of kidney cancer, the WHO classification system, and the growing role of molecular classification for diagnosis, prognosis, and therapy of this disease.

Profiling and classification tree applied to renal epithelial tumours

AIMS

Selection of the relevant combination from a growing list of candidate immunohistochemical biomarkers constitutes a real challenge. The aim was to establish the minimal subset of antibodies to achieve classification on the basis of 12 antibodies and 309 renal tumours.

METHODS AND RESULTS

Seventy-nine clear cell (CC), 88 papillary (PAP) and 50 chromophobe (CHRO) renal cell carcinomas, and 92 oncocytomas (ONCO) were immunostained for renal cell carcinoma antigen, vimentin, cytokeratin (CK) AE1-AE3, CK7, CD10, epithelial membrane antigen, alpha-methylacyl-CoA racemase (AMACR), c-kit, E-cadherin, Bcl-1, aquaporin 1 and mucin-1 and analysed by tissue microarrays. First, unsupervised hierarchical clustering performed with immunohistochemical profiles identified four main clusters-cluster 1 (CC 67%), 2 (PAP 98%), 3 (CHRO 67%) and 4 (ONCO 100%)-demonstrating the intrinsic classifying potential of immunohistochemistry. A series of classification trees was then automatically generated using Classification And Regression Tree software. The most powerful of these classification trees sequentially used AMACR, CK7 and CD10 (with 86% CC, 87% PAP, 79% CHRO and 78% ONCO correctly classified in a leave-one-out cross-validation test). The classifier was also helpful in 22/30 additional cases with equivocal features.

CONCLUSION

The classification tree method using immunohistochemical profiles can be applied successfully to construct a renal tumour classifier.

Claudin-7 immunohistochemistry in renal tumors: a candidate marker for chromophobe renal cell carcinoma identified by gene expression profiling

CONTEXT

The differential diagnosis of eosinophilic renal tumors can be difficult by light microscopy. In particular, chromophobe renal cell carcinoma (RCC) is difficult to distinguish from oncocytoma. This differential diagnosis is important because chromophobe RCC is malignant, whereas oncocytoma is benign. Furthermore, chromophobe RCC has distinct malignant potential and prognosis compared with eosinophilic variants of other RCC subtypes. Immunohistochemistry is useful for distinguishing chromophobe RCC from other subtypes of renal carcinoma, but no expression marker reliably separates chromophobe RCC from oncocytoma.

OBJECTIVE

In a previous gene expression microarray analysis of renal tumor subtypes, we found the distal nephron markers claudin-7 and claudin-8 to be overexpressed in chromophobe RCC versus oncocytoma and other tumor subtypes. We have confirmed similar findings in independent microarray data and validated differential claudin-7 protein expression by immunohistochemistry.

DESIGN

Immunohistochemical analysis of claudin-7 in 36 chromophobe RCCs, 43 oncocytomas, 42 clear cell RCCs, and 29 papillary RCCs.

RESULTS

Membranous claudin-7 expression was detected in 67% chromophobe RCCs, compared with 0% clear cell RCCs, 28% papillary RCCs, and 26% oncocytomas (P < .001).

CONCLUSIONS

Based on microarray and immunohistochemical data, we propose claudin-7 to be a candidate expression marker for distinguishing chromophobe RCC from other renal tumor subtypes, including the morphologically similar oncocytoma. The clinical utility of claudin-7 should be validated in independent studies of renal tumors, possibly in combination with additional targets in a multiplex immunohistochemical panel.

Identification and characterization of Birt-Hogg-Dubé associated renal carcinoma

The Birt-Hogg-Dubé (BHD) gene is responsible for BHD syndrome, a rare autosomal dominant disease, characterized by benign hair follicle tumours, spontaneous pneumothorax and renal neoplasms with diverse histology. To elucidate its involvement in the development of renal neoplasms, we examined a total of 100 sporadic renal tumours with various histological subtypes for BHD mutation by SSCP-sequencing analyses. We found one germline insertion mutation in the C8 hotspot of exon 11 (c.1733insC), which is known to have a strong association with renal tumour occurrence. The germline-mutated patient suffered from solitary renal cell carcinoma (RCC) but did not have any other BHD manifestations or family history. The tumour revealed heterogeneous cytomorphology, mainly a mixture of eosinophilic and focally clear cells with tubulopapillary architecture. In this tumour, both BHD alleles were inactivated by germline mutation concomitant with loss of heterozygosity, and the amount of BHD mRNA detected by real-time quantitative PCR (RQ-PCR) was very low. Renal tumour subtype/nephron segment-specific gene expression detected by RQ-PCR demonstrated that the tumour expressed relatively high amounts of alpha-methylacyl-CoA racemase (AMACR) and the KIT oncogene, but relatively low amounts of carbonic anhydrase IX (CA9), aquaporin 1 (AQP1), claudin 7 (CLDN7), parvalbumin (PVALB), chloride channel Kb (CLCNKB) and 11-beta-hydroxysteroid dehydrogenase 2 (HSD11B2), suggesting diverse mRNA signatures. Further clustering analysis of 88 renal tumours based on expression of these eight genes sub-classified the tumour as close to oncocytomas and chromophobe RCCs, which are considered distal nephron-associated tumours. These data suggest that somatic mutation of BHD is relatively rare in Japanese patients. The BHD-mutated RCC identified in this study, which exhibits heterogeneous biological features in both morphology and gene expression signatures, seems to deviate from our current understanding of renal tumour classification.

Gene expression profiling in kidney cancer: combining differential expression and chromosomal and pathway analyses

The high-throughput gene expression profiling by microarray analysis has enabled researchers to compare the relative expression levels of thousands of genes in diseases, including cancer. By identifying how these genes cluster in different carcinomas, these profiling techniques can improve the accuracy of classifying subtypes of tumors and their prognoses and could help determine which therapy is appropriate for each patient with cancer. These efforts aim to provide more effective personalized medicine. To reach this goal, the analysis of microarray data has also evolved and become more sophisticated and complex. Herein, using kidney cancer as an example, we demonstrate the use of microarray data for different bases of analysis, ie, direct differential expression, deduced chromosomal alteration, and pathways signature. We believe combining these will enhance the value of microarray studies and will better serve the goals we try to achieve using these data.

Genome-wide array-based comparative genomic hybridization analysis of pancreatic adenocarcinoma: identification of genetic indicators that predict patient outcome

We analyzed the subchromosomal numerical aberrations of 44 surgically resected pancreatic adenocarcinomas by array-based comparative genomic hybridization. The aberration profile ranged widely between cases, suggesting the presence of multiple or complementary mechanisms of evolution in pancreatic cancer, and was associated with lymph node metastasis and venous or serosal invasion. A large number of small loci, previously uncharacterized in pancreatic cancer, showed non-random loss or gain. Frequent losses at 1p36, 4p16, 7q36, 9q34, 11p15, 11q13, 14q32-33, 16p13, 17p11-13, 17q11-25, 18q21-tel, 19p13, 21q22 and 22q11-12, and gains at 1q25, 2p16, 2q21-37, 3q25, 5p14, 5q11-13, 7q21, 7p22, 8p22, 8q21-23, 10q21, 12p13, 13q22, 15q13-22 and 18q11 were identified. Sixteen loci were amplified recurrently. We identified novel chromosomal alterations that were significantly associated with a range of malignant phenotypes. Gain of LUNX, HCK, E2F1 and DNMT3b at 20q11, loss of p73 at 1p36 and gain of PPM1D at 17q23 independently predicted patient outcome. Expression profiling of amplified genes identified Smurf1 and TRRAP at 7q22.1, BCAS1 at 20q13.2-3, and VCL at 10q22.1 as potential novel oncogenes. Our results contribute to a complete description of genomic structural aberrations and the identification of potential therapeutic targets and genetic indicators that predict patient outcome in pancreatic adenocarcinoma.

Elucidation of the molecular signatures of renal cell carcinoma by gene expression profiling

Renal cell carcinoma (RCC) is the 10th most common cancer in United States. It is a heterogeneous disease with various histologic types. Since high-throughput technologies such as microarrays have been introduced, molecular confirmation of previously known findings in RCC has been made and new molecular findings have emerged. We review the accumulating advances in this field and their clinical implications. The published data so far have proved to be significant and promising, and numerous microarray studies with larger number of cases are currently ongoing or being planned. Although various clinical parameters are being refined for diagnosis and prognosis, these data obtained by microarray studies will undoubtedly contribute to both and eventually impacts the treatment of RCC.

KIT (CD117): a review on expression in normal and neoplastic tissues, and mutations and their clinicopathologic correlation

CD117 (KIT) is a type III receptor tyrosine kinase operating in cell signal transduction in several cell types. Normally KIT is activated (phosphorylated) by binding of its ligand, the stem cell factor. This leads to a phosphorylation cascade ultimately activating various transcription factors in different cell types. Such activation regulates apoptosis, cell differentiation, proliferation, chemotaxis, and cell adhesion. KIT-dependent cell types include mast cells, some hematopoietic stem cells, germ cells, melanocytes, and Cajal cells of the gastrointestinal tract, and neoplasms of these cells are examples of KIT-positive tumors. Other KIT-positive normal cells include epithelial cells in skin adnexa, breast, and subsets of cerebellar neurons. KIT positivity has been variably reported in sarcomas such as angiosarcoma, Ewing sarcoma, synovial sarcoma, leiomyosarcoma, and MFH; results of the last three are controversial. The variations in published data may result from incomplete specificity of some polyclonal antibodies, possibly contributed by too high dilutions. Also, KIT is expressed in pulmonary and other small cell carcinomas, adenoid cystic carcinoma, renal chromophobe carcinoma, thymic, and some ovarian and few breast carcinomas. A good KIT antibody reacts with known KIT positive cells, and smooth muscle cells and fibroblasts are negative. KIT deficiency due to hereditary nonsense/missense mutations leads to disruption of KIT-dependent functions such as erythropoiesis, skin pigmentation, fertility, and gastrointestinal motility. Conversely, pathologic activation of KIT through gain-of-function mutations leads to neoplasia of KIT-dependent and KIT-positive cell types at least in three different systems: mast cells/myeloid cells--mastocytosis/acute myeloid leukemia, germ cells--seminoma, and Cajal cells--gastrointestinal stromal tumors (GISTs). KIT tyrosine kinase inhibitors such as imatinib mesylate are the generally accepted treatment of metastatic GISTs, and their availability has prompted an active search for other treatment targets among KIT-positive tumors such as myeloid leukemias and small cell carcinoma of the lung, with variable and often nonconvincing results.

Targeted Anti-Cancer Therapies for Renal Cancer

In the past several years, significant advances in the underlying biological mechanisms of renal cell cancer, particularly the role of tumour angiogenesis, have permitted the design of molecularly targeted therapeutics. For this review, single-agent therapies inhibiting the following different targets were identified in the published literature: epithelial growth factor receptor, vascular endothelial growth factor receptor, basic fibroblast growth factor receptor, platelet-derived growth factor, nuclear factor-kappabeta, the mammalian target of rapamycin (mTOR) pathway, raf kinase pathway and tyrosine kinase pathway. Distinct fields of clinical research have emerged--monoclonal antibodies, small molecules, nanopeptides and immunomodulators. All therapies demonstrated acceptable toxicity profiles. Clinical benefit was assessed on the basis of the reported criteria for each study, and antitumour response (regression or delay in progression-free survival) ranged from 5% to 71%. On the basis of the limited studies to date, targeted therapies offer the greatest clinical benefit in the management of this malignancy, although additional basic research is still warranted to further improve clinical outcome.

Rare Expression of KIT and Absence of KIT Mutations in High Grade Renal Cell Carcinoma

PURPOSE

RCCs with sarcomatoid differentiation have been reported to frequently express KIT protein, suggesting that imatinib mesylate (STI-571 or Gleevectrade mark) may be effective treatment for these aggressive tumors. We determined the frequency of KIT expression and mutation in a large series of high grade RCCs.

MATERIALS AND METHODS

We identified 194 patients who underwent nephrectomy for unilateral, sporadic nuclear grade 4 RCC between 1970 and 2002, including 123 with sarcomatoid differentiation. Sections from representative paraffin embedded tissue blocks were immunostained in an autostainer using ethylenediaminetetraacetic acid antigen retrieval, a polyclonal KIT antibody and the avidin-biotin peroxidase complex method. Mutational analysis was performed in all immunopositive and select negative cases by polymerase chain reaction amplification of KIT exons 9, 11, 13 and 17.

RESULTS

Only 7 tumors (3.6%) showed KIT expression, including 5 of the 123 (4.1%) with sarcomatoid differentiation. Four of the 7 tumors showed focal staining only. No mutations were identified in the 7 positive cases or in 8 randomly selected negative samples. Death from RCC occurred in all 7 patients with KIT positive tumors at a median of 0.6 years (range 0.3 to 2.3) and in 139 of 187 with KIT negative tumors at a median of 0.8 years (range 0 to 10.2).

CONCLUSIONS

KIT expression was identified in less than 5% of high grade RCCs with or without sarcomatoid differentiation but none of the tumors showed KIT mutations. These findings indicate that imatinib therapy is unlikely to be effective in patients with high grade RCC.

Identification of fatty acid binding proteins as markers associated with the initiation and/or progression of renal cell carcinoma

Renal cell carcinoma (RCC) representing the most common neoplasia of the kidney in Western countries is a histologic diverse disease with an often unpredictable course. The prognosis of RCC is worsened with the onset of metastasis, and the therapies currently available are of limited success for the treatment of metastatic RCC. Although gene expression analyses and other methods are promising tools clarifying and standardizing the pathological classification of RCC, novel innovative molecular markers for the diagnosis, prognosis, and for the monitoring of this disease during therapy as well as potential therapeutic targets are urgently needed. Using proteome-based strategies, a number of RCC-associated markers either over-expressed or down-regulated in tumor lesions in comparison to the normal epithelium have been identified which have been implicated in tumorigenesis, but never linked to the initiation and/or progression of RCC. These include members of the fatty acid binding protein family, which have the potential to serve as diagnostic or prognostic markers for the screening of RCC patients.

KIT expression in normal and neoplastic renal tissues: Immunohistochemical and molecular genetic analysis

Renal chromophobe cell carcinomas (ChCC) and oncocytomas express KIT. This character seems to reflect their common histogenesis from distal nephrons. In the normal kidney, however, the expression and localization of KIT are unclear. KIT expression in angiomyolipoma and congenital mesoblastic nephroma (CMN), is still controversial. c-kit mutations are reportedly rare in ChCC, but there is little information in other renal neoplasms, and no reported data on mutations of platelet-derived growth factor receptor (PDGFR). In order to address these issues the authors examined five ChCC, five oncocytomas, seven papillary cell carcinomas, two collecting duct carcinomas, 12 angiomyolipomas, and three CMN, as well as 10 normal renal tissues. In the normal kidney KIT was specifically expressed in the distal nephrons. Nine of 12 (75%) angiomyolipomas contained scattered KIT-positive cells, whereas all three CMN were completely negative for KIT. The presence of KIT-positive cells in angiomyolipomas was likely to correspond to that of melanocytic marker-positive cells, which mainly showed epithelioid morphology. Polymerase chain reaction-single-strand conformation polymorphism showed no evidence of mutations of c-kit or PDGFR in any of the tumors examined.

PKC theta, a novel immunohistochemical marker for gastrointestinal stromal tumors (GIST), especially useful for identifying KIT-negative tumors

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor in the digestive tract and the majority of GIST has characteristic gain-of-function mutations of the c-kit gene, which encodes the KIT receptor for stem cell factor. The present study aimed to establish the usefulness of protein kinase C theta (PKC theta) as an immunohistochemical marker for GIST in comparison with KIT immunohistochemistry. PKC theta immunohistochemistry was carried out not only on 48 cases of GIST and another 40 cases of gastrointestinal mesenchymal tumors, but also on 24 cases of various tumors known to be immunohistochemically positive for KIT. Immunohistochemically, 41 out of 48 cases (85%) of GIST were positive for PKC theta, and its expression was confirmed by Western blot analysis using six cases of surgically resected GIST. In the present study there were six GIST immunohistochemically negative for KIT, which histologically revealed a myxoid epithelioid appearance characteristic to that of GIST with platelet-derived growth factor receptor alpha mutation. All six GIST were immunohistochemically positive for PKC theta. No PKC theta immunoreactivity was observed in other gastrointestinal mesenchymal tumors and various KIT-positive tumors except for three cases (14%) of gastrointestinal schwannomas. The present study revealed that PKC theta is an immunohistochemically novel and useful marker for GIST, especially for GIST negative for KIT.

Expression of KIT (CD117) in renal cell carcinoma and renal oncocytoma

OBJECTIVE

Overexpression of KIT (CD117), a tyrosine kinase receptor, has been reported in a variety of tumors, some of which are susceptible to therapy with imatinib mesylate. Our aim was to analyze KIT expression immunohistochemically in renal cell carcinomas (RCCs) and in oncocytomas.

METHODS

Routinely processed, paraffin-embedded specimens from 61 RCCs and 13 renal oncocytomas were investigated immunohistochemically. Cytoplasmic and membrane-bound KIT staining of tumor cells was determined semiquantitatively. A subset of cases was additionally analyzed for point mutations of c-kit exon 17 by peptide nucleic acid-mediated nested polymerase chain reaction-clamping.

RESULTS

All cases of oncocytomas and chromophobe RCCs showed membrane-bound KIT positivity, while about three-quarters of cases showed cytoplasmic reactivity. All other types of RCC were found KIT negative. Within the group of chromophobe RCCs, negative cytoplasmatic KIT reactivity was significantly correlated with advanced tumor stage (pT > or = 2; p = 0.036). Analysis of c-kit exon 17 revealed no 'gain-of-function' mutation like the codon 816 Asp-->Val mutation (D816V).

CONCLUSIONS

KIT expression is a hallmark of oncocytoma and chromophobe RCC. Since all other types of RCC were found to be KIT negative, immunohistochemical KIT reactivity may be used as an additional diagnostic criterion to distinguish chromophobe RCC from other RCC types. KIT reactivity and the absence of c-kit mutation D816V in chromophobe RCC justify speculations that imatinib mesylate therapy could be effective in patients with advanced disease.

The usefulness of immunohistochemical markers in the differential diagnosis of renal neoplasms

Histologic subtyping of RCC has been shown to be of prognostic value; therefore, it is important to classify malignant epithelial tumors of the kidney correctly and also to differentiate them from benign ones. Overlapping morphologic features of renal tumors sometimes make histologic subtyping difficult. The accurate diagnosis and classification of RCC are based on cytoarchitectural features and require correlation with immunophenotype and cytogenetic characteristics. RCC Ma and CD10, two markers with relative renal specificity, have been used to confirm a diagnosis of suspected RCC and can facilitate the accurate diagnosis of metastatic RCC, in particular, in FNA. Although CCRCC and PRCC share most immunomarkers, CK7 and AMACR expression can be helpful in the differential diagnosis of challenging histologic variants of the two. In addition, E-cadherin aids in the distinction between types 1 and 2 PRCC. Useful markers in the differential diagnosis between ChRCC and CCRCCare CK7, RCC Ma, CD10, VIM, CD117, parvalbumin, and E-cadherin. We propose CK7/CK20/CD15 as a useful primary immunopanel to differentiate ChRCC from ONC reliably.

KIT and RCC Are Useful in Distinguishing Chromophobe Renal Cell Carcinoma From the Granular Variant of Clear Cell Renal Cell Carcinoma

The distinction between chromophobe renal cell carcinoma, the granular cell variant of clear cell renal cell carcinoma, and renal oncocytoma is a common diagnostic dilemma. The usefulness of KIT, CD10, RCC, and RON in the differential diagnosis of these renal epithelial tumors was investigated. KIT was 100% positive in chromophobe renal cell carcinoma (11 of 11) and renal oncocytoma (12 of 12). The KIT staining pattern was identical in both tumor types, with cytoplasmic membrane attenuation, and fine granular cytoplasmic staining. In contrast, KIT was absent in all granular cell variants of clear cell renal cell carcinoma (0 of 6). RCC was observed in more than 80% of the granular cell variant of clear cell renal cell carcinoma (5 of 6) but was negative in all chromophobe renal cell carcinomas (0 of 11) and renal oncocytomas (0 of 12). CD10 was expressed in 100% of the granular cell variant of clear cell renal cell carcinoma (6 of 6), 72% of chromophobe renal cell carcinomas (8 of 11), and 58% of renal oncocytomas (7 of 12). RON was 100% positive in the chromophobe renal cell carcinomas (11 of 11) and renal oncocytomas (12 of 12) but only 50% positive in the granular cell variant of clear cell renal cell carcinoma (3 of 6). Colloidal iron was diffusely and strongly positive in more than 80% of the chromophobe renal cell carcinomas (9 of 11), focally and weakly positive in 41% of the renal oncocytomas (5 of 12) but negative in all granular cell variant of clear cell renal cell carcinoma (0 of 6). The above results demonstrate that: 1) KIT is a very sensitive marker for both chromophobe renal cell carcinoma and renal oncocytoma; 2) immunohistochemistry using antibodies to KIT combined with RCC was sufficient to discriminate between chromophobe renal cell carcinoma and the granular cell variant of clear cell renal cell carcinoma; and 3) neither RON, nor KIT, nor a combination of this panel can be used to distinguish chromophobe renal cell carcinoma from renal oncocytoma. Colloidal iron staining aided in this distinction for the majority of the chromophobe renal cell carcinomas (more than 80% positive) and renal oncocytomas (close to 60% negative).

S100A1 and KIT gene expressions in common subtypes of renal tumours

AIM

The aim of this study is to evaluate the S100A1 and KIT as gene markers for the differentiation of common subtypes of renal tumours.

METHODS

Fifty-five tissue samples (15 clear cell RCCs, 15 papillary RCCs, 7 chromophobe RCCs, 8 oncocytomas and 10 normal renal tissues) were studied The gene expressions of S100A1 and KIT were analysed by one-step RT-PCR by using the specific primers.

RESULTS

S100A1 was expressed in 2/15 clear cell RCCs, 11/15 papillary RCCs, 7/8 oncocytomas and in 0/7 chromophobe RCCs. KIT gene was expressed in 6/7 chromophobe RCCs and 7/8 oncocytomas while 0/15 clear cell RCCs and 1/15 papillary RCCs expressed kit gene. Normal tissue expressed neither S100A1 nor KIT gene.

CONCLUSION

S100A1 and KIT can be used as gene markers for the differentiation of common subtypes of renal tumours.

Kit (CD117) immunoreactivity is rare in renal cell and upper urinary tract transitional cell carcinomas

OBJECTIVE

To investigate the presence of Kit (CD117), a transmembrane tyrosinase-kinase receptor, in primary and metastatic renal cell carcinomas (RCCs) and upper urinary tract transitional cell carcinomas (TCCs).

MATERIALS AND METHODS

In human neoplasia, overexpression of Kit has been related to cell proliferation, differentiation, adhesion and control of apoptosis. If present, Kit may provide a suitable target for tumour therapy. Formalin-fixed and paraffin-embedded specimens of 180 primary and 58 metastatic RCCs and 54 upper urinary tract TCCs were immunostained for Kit (CD117) using a tissue microarray technique.

RESULTS

In RCCs, immunoreactivity for CD117 was detected in only two of 23 (9%) chromophobe tumours, whereas all 137 conventional and 20 papillary subtypes, and metastatic RCC tissues, lacked CD117 immunoreactivity. In TCCs, CD117 expression of <10% cancer cells was found in two of 53 (4%) cases. Stromal mast cells served as a positive control and showed specific immunostaining.

CONCLUSION

Kit immunoreactivity is infrequent in both RCCs and upper urinary tract TCCs. Thus, routine screening of tumour tissues for Kit by immunohistochemistry appears to be cost-ineffective and cannot be recommended. Moreover, the lack of substantial Kit immunoreactivity in both primary and metastatic carcinomas does not provide a rationale to investigate imatinib mesylate therapy in clinical trials including patients with advanced disease.

C-kit expression in renal oncocytomas and chromophobe renal cell carcinomas

C- kit encodes the membrane-bound tyrosine kinase KIT, whose expression has been identified in several types of human neoplasms. Recently, KIT has been reported to be a marker for chromophobe renal cell carcinoma (RCC) and renal angiomyolipoma. However, expression of this molecule has not been adequately studied in other renal tumors, particularly oncocytoma, which may morphologically resemble chromophobe RCC. In this study, we analyzed c- kit messenger RNA (mRNA) levels in 17 chromophobe RCCs and 20 renal oncocytomas obtained from complementary DNA (cDNA) microarrays. Furthermore, comprehensive immunohistochemical analysis of KIT protein using a monoclonal antibody was performed in 226 renal tumors including chromophobe RCC (n=40), oncocytoma (n=41), clear-cell RCC (n=40), renal angiomyolipoma (n=29), and papillary RCC (n=21) on tissue microarrays (TMAs) and was compared with immunostaining results from 25 chromophobe RCCs and 30 oncocytomas using standard sections. The staining intensity was semiquantitatively graded on a 3-tier scoring system. All chromophobe RCCs and oncocytomas showed significant overexpression of c- kit mRNA. The average increase of mRNA compared with normal kidney tissue was 7.4-fold for chromophobe RCCs and 7.4-fold for oncocytomas. Immunohistochemical expression of KIT was found in most chromophobe RCCs (95% in TMAs and 96% in conventional sections) and oncocytomas (88% in TMAs and 100% in conventional sections) but was infrequently observed in renal angiomyolipomas (17%), papillary RCCs (5%), and clear-cell RCCs (3%). Furthermore, the average KIT immunoreactivity in TMAs was stronger in chromophobe RCC (1.93) and oncocytoma (2.07) than in other subtypes of renal tumors tested, including angiomyolipomas (0.17), papillary RCCs (0.05), and clear-cell RCCs (0.03). In conclusion, we found a significant elevation of c- kit mRNA by cDNA expression microarrays and overexpression of KIT protein by immunohistochemistry not only in chromophobe RCCs but also in oncocytomas. In contrast, immunohistochemical expression of KIT was not detected in most other types of renal cell tumors evaluated. The differential expression of c- kit in these renal tumors may have diagnostic and therapeutic implications.

Functional promoter upstream p53 regulatory sequence of IGFBP3 that is silenced by tumor specific methylation

BACKGROUND

Insulin-like growth factor binding protein (IGFBP)-3 functions as a carrier of insulin-like growth factors (IGFs) in circulation and a mediator of the growth suppression signal in cells. There are two reported p53 regulatory regions in the IGFBP3 gene; one upstream of the promoter and one intronic. We previously reported a hot spot of promoter hypermethylation of IGFBP-3 in human hepatocellular carcinomas and derivative cell lines. As the hot spot locates at the putative upstream p53 consensus sequences, these p53 consensus sequences are really functional is a question to be answered.

METHODS

In this study, we examined the p53 consensus sequences upstream of the IGFBP-3 promoter for the p53 induced expression of IGFBP-3. Deletion, mutagenesis, and methylation constructs of IGFBP-3 promoter were assessed in the human hepatoblastoma cell line HepG2 for promoter activity.

RESULTS

Deletions and mutations of these sequences completely abolished the expression of IGFBP-3 in the presence of p53 overexpression. In vitro methylation of these p53 consensus sequences also suppressed IGFBP-3 expression. In contrast, the expression of IGFBP-3 was not affected in the absence of p53 overexpression. Further, we observed by electrophoresis mobility shift assay that p53 binding to the promoter region was diminished when methylated.

CONCLUSION

From these observations, we conclude that four out of eleven p53 consensus sequences upstream of the IGFBP-3 promoter are essential for the p53 induced expression of IGFBP-3, and hypermethylation of these sequences selectively suppresses p53 induced IGFBP-3 expression in HepG2 cells.

Renal cell carcinoma: review of novel single-agent therapeutics and combination regimens

A search of the Medline database and ASCO 2003 conference proceedings was conducted to identify clinical trials currently underway using single-agent therapy for renal cell carcinoma (RCC). Combination trials were identified using the ASCO 2003 conference proceedings. Fourteen single-agent therapies employing different mechanisms of action were identified in the published literature: imatinib mesylate (Gleevec); bevacizumab (Avastin); thalidomide (Thalomid); gefitinib (ZD1839) (Iressa); cetuximab (IMC-C225) (Erbitux); bortezomib (PS-341) (Velcade); HSPPC-96 (Oncophage); BAY 59-8862; ABT-510; G250; CCI-779; SU5416; PTK/ZK; and ABX-EGF. Six distinct fields of clinical research have emerged: monoclonal antibodies, small molecules, vaccines, second-generation taxanes, nonapeptides and immunomodulators. Five combination regimens, primarily biological response modifiers (interleukin-2 or interferon-alpha), chemotherapy- or thalidomide-based, were identified. All therapies demonstrated acceptable toxicity profiles. Clinical benefit was assessed based on each study's reported criteria: antitumor response (regression or stability) ranged from 5% to 71%. In the past several years, significant advances in the underlying biological mechanisms of RCC, particularly the role of tumor angiogenesis, have permitted the design of molecularly targeted therapeutics. Based on preliminary and limited studies, combination therapies offer the greatest clinical benefit in the management of this malignancy, although additional basic research is still warranted.

Gene expression profiling of renal cell carcinoma

Renal cell carcinoma (RCC) is a histologically diverse disease, with variable and often unpredictable clinical behavior. The prognosis worsens dramatically with the onset of clinical metastasis, and current regimens of systemic therapy yield only modest benefits for metastatic RCC. Gene expression profiling is a promising technique for refining the diagnosis and staging of RCC, as well as for highlighting potential therapeutic targets. We review the recent advances in expression profiling of RCC and discuss the clinical and biological insights obtained from these studies.

Kinase Inhibition with BAY 43–9006 in Renal Cell Carcinoma

BAY 43-9006 is an oral inhibitor of CRAF, wild-type BRAF, mutant V599E BRAF, vascular endothelial growth factor receptor (VEGFR) 2, VEGFR3, mVEGFR2, FLT-3, platelet-derived growth factor receptor, p38, and c-kit among other kinases. A Phase I study of BAY 43-9006 identified 400 mg orally twice daily as the recommended Phase II dose. The Phase II results of a study of BAY 43-9006 at 400 mg orally twice daily were particularly interesting in patients with renal cell carcinoma. Data from the first 41 patients with renal cell carcinoma showed that 30% of patients had stable disease (defined as between 25% reduction and 25% growth), 40% had responded (defined as >25% reduction), and 30% had progressed. Disease could be stabilized for periods in excess of a year. Some lesions became cystic and could actually enlarge while developing a low attenuation core. This phenomenon is recognized in the treatment of gastrointestinal stromal tumors with imatinib mesylate. The toxic effects of BAY 43-9006 were manageable and included hypertension, edema, diarrhea, hand and foot syndrome, rash, and hair loss where the rash involved the scalp. There was an impression of tachyphylaxis such that patients who required a dose reduction could be restored to full dose after a few months. A Phase III randomized, placebo-controlled trial of BAY 43-9006 has started for patients whose renal cell carcinoma has progressed within 6 months of immunotherapy. Combination studies with interferon, interleukin 2, bevacizumab, and chemotherapy are under consideration. The therapeutic targets of BAY 43-9006 in renal cell carcinoma remain unclear. Unlike melanoma, BRAF mutations have not been found in renal cell carcinoma. Other candidate targets include VEGFR2 and VEGFR3.