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-β 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 (∼0.1 μmol/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.

Purpose: Intratumoral microvascular density (MVD) has been controversial as an indicator of prognosis in clear cell renal cell carcinoma (CCRCC). Classification of the intratumoral blood vessels based on differential expressions of blood vessel markers has not been correlated with patient prognosis in CCRCC. In this study, we aimed to evaluate the association of different categories of blood vessels with the patients'outcomes. Experimental Design: Seventy-eight CCRCC patients who underwent nephrectomy alone were enrolled. Paraffin-embedded CCRCC tissues, together with 16 nonmalignant kidney cortex tissues, were used in tissue microarray analyses and conventional section analyses. The characteristics of intratumoral blood vessels were identified by multiple blood vessel markers and pericyte markers. A computerized image analysis program was used to quantitatively calculate the vascular density. Results: Two distinct types of microvessels were identified in CCRCC: undifferentiated (CD31 + / CD34 À ) and differentiated (CD34 + ) vessels. A higher undifferentiated MVD significantly correlated with higher tumor grades and shorter patient survival. In contrast, a higher differentiated MVD significantly correlated with lower tumor grade and longer survival. Multivariate analyses showed that undifferentiated MVD was an independent prognostic factor for patient survival. An inverse correlation between undifferentiated MVD and differentiated MVD was also identified in CCRCC. Conclusions: This is the first report showing distinct types of vasculature in CCRCC correlated with contrasting prognoses. A refined classification of CCRCC based on vasculature is therefore important for evaluating prognosis, and it may also have therapeutic implications.Angiogenesis, the generation of new blood vessels from preexisting microvasculature, is an essential process for tumor growth and is related to blood-borne metastasis (1). The quantification of various aspects of tumor vasculature might provide an indication of angiogenic activity. Microvascular density (MVD) is an often-quantified variable of tumor vasculature. Recent reports suggest that increased MVD is associated with poor outcome in several malignancies, including breast, prostate, lung, and nasopharyngeal cancers (2 -7).Clear cell renal cell carcinoma (CCRCC) is the most common subtype of malignant renal tumors, representing f80% of renal cell carcinoma. Despite improvements in medical imaging for early diagnosis, >40% of the patients with clear cell metastatic cancers remain incurable (8). The underlying mechanism of CCRCC metastasis is unclear.

For several decades etiological diagnosis of patients with idiopathic mental retardation (MR) and multiple congenital anomalies (MCA) has relied on chromosome analysis by karyotyping. Conventional karyotyping allows a genome-wide detection of chromosomal abnormalities but has a limited resolution. Recently, array-based comparative genomic hybridization (array CGH) technologies have been developed to evaluate DNA copy-number alterations across the whole-genome at a much higher resolution. It has proven to be an effective tool for detection of submicroscopic chromosome abnormalities causing congenital disorders and has recently been adopted for clinical applications. Here, we investigated four high-density array platforms with a theoretical resolution < or =100 kb: 33K tiling path BAC array, 500K Affymetrix SNP array, 385K NimbleGen oligonucleotide array and 244K Agilent oligonucleotide array for their robustness and implementation in our diagnostic setting. We evaluated the practical performance based on the detection of 10 previously characterized abnormalities whose size ranged from 100 kb to 3 Mb. Furthermore, array data analysis was performed using four computer programs developed for each corresponding platform to test their effective ability of reliable copy-number detection and their user-friendliness. All tested platforms provided sensitive performances, but our experience showed that accurate and user-friendly computer programs are of crucial importance for reliable copy-number detection.

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