Size-based isolation and detection of renal carcinoma cells from whole blood.

Renal cell carcinoma (RCC) is a tumour type with an indolent growth pattern and rather vague symptoms. The present study developed a platform for liquid biopsy of RCC based upon the isolation of circulating tumour cells (CTCs). Founded on the observation that RCC tumour cells are considerably larger than leucocytes, the present study employed a microfluidics-based system for isolation of RCC CTCs from whole blood. Using this system, it was revealed that 66% of spiked-in RCC tumour cells could be retrieved using this approach. Furthermore, it was demonstrated that these cells could be molecularly detected with digital PCR using RCC-specific genes down to one tumour cell, whilst avoiding detection in samples lacking tumour cells. Finally, subtype specific transcripts were identified to distinguish the different subtypes of RCC, which were then validated in patient tumours. The present study established a novel workflow for the isolation of RCC CTCs from whole blood, with the potential to detect these cells irrespective of subtype.

Sarcomatoid conversion of clear cell renal cell carcinoma in relation to epithelial-to-mesenchymal transition.

Approximately 8% of clear cell renal cell carcinoma cases contain regions of radically different morphology, demonstrating a mesenchymal appearance histologically resembling sarcomas. These biphasic neoplasms are called sarcomatoid clear cell renal cell carcinoma. Patients diagnosed with sarcomatoid clear cell renal cell carcinoma face a considerably worse prognosis due to an increased propensity for metastasis. In the present study we investigate whether the sarcomatoid conversion of clear cell renal cell carcinoma could be interpreted as linked to the process of epithelial-mesenchymal transition. Using 6 biphasic clear cell renal cell carcinoma cases we show that sarcomatoid clear cell renal cell carcinoma shares characteristic markers associated with loss of von Hippel-Lindau tumor suppressor with conventional clear cell renal cell carcinoma and also exhibits a markedly higher proliferative index. Furthermore the sarcomatoid elements demonstrate an enhanced expression of epithelial-mesenchymal transition related mesenchymal markers as compared with the clear cell renal cell carcinoma counterparts. We further selected a representative case, clinically demonstrating direct overgrowth of the sarcomatoid component into the liver and colon, for extended immunohistochemical characterization, resulting in a further set of positive and negative epithelial-mesenchymal transition markers as well as pronounced transforming growth factor ß positivity, indicating that sarcomatoid clear cell renal cell carcinoma may be associated to epithelial-mesenchymal transition. Transforming growth factor ß1 exposure of in vitro cultured primary clear cell renal cell carcinoma cells resulted in cells adopting a mesenchymal morphology similar to sarcomatoid clear cell renal cell carcinoma. Corresponding changes in RNA levels for key epithelial-mesenchymal transition markers were also seen. We therefore suggest that sarcomatoid clear cell renal cell carcinoma morphologically and immunohistochemically may represent a completed epithelial-mesenchymal transition and that transforming growth factor ß1 could be an important driving force during the sarcomatoid transdifferentiation of clear cell renal cell carcinoma.

High-resolution genomic profiling of an adult Wilms' tumor: evidence for a pathogenesis distinct from corresponding pediatric tumors.

Wilms' tumor (WT), the most common kidney tumor among children, is characterized by a triphasic morphology consisting of blastemal, epithelial, and stromal components. Adult WT is a rare malignancy displaying similar histological features. We here present the first published high-resolution genomic analysis of a mixed-type adult WT. This revealed a more pronounced genetic complexity than usually observed in children with mixed-type WT. The majority of chromosomes displayed uniparental disomies, and microdeletions were present in genes with known importance for tumor formation (LRP1B, FHIT, and WWOX) or organogenesis (NEGR1 and ZFPM2), abnormalities not previously reported for pediatric WT. Our results indicate that adult WT is a biological entity distinct from the corresponding pediatric tumor type.

Dissecting karyotypic patterns in renal cell carcinoma: an analysis of the accumulated cytogenetic data.

Renal cell carcinoma (RCC) is one of the most frequent malignancies in Western societies. The most common subtypes are conventional (clear-cell) and papillary carcinomas, which account for about 75 and 10% of cases, respectively. Cytogenetically, conventional RCC is the best-studied subtype and is characterized by chromosomal losses: loss of the short arm of chromosome 3 being the most common. Papillary tumors frequently show gains of chromosomes 7 and 17, and the more progressed forms have, in addition, gains of chromosomes 16, 12, and 20. In the present investigation we used 796 RCC karyotypes to identify the most frequent genomic imbalances. Tumor cases were then classified with respect to the presence or absence of these imbalances and statistically analyzed to assess the order of appearance of chromosomal imbalances, as well as possible karyotypic pathways and cytogenetic subtypes. We established a temporal order by which the different imbalances occur and showed that at least two cytogenetic pathways exist in RCC, one hypodiploid characterized by presence of 3p- and one hyperdiploid characterized by the presence of +7. The data suggest that conventional-type tumors predominantly evolve through the hypodiploid pathway but that an alternative route may be by hyperdiploidy if 3p- is present. Tumors with a papillary growth pattern predominantly progress through the hyperdiploid pathway. The analyses also revealed three possible cytogenetic subtypes of the papillary tumors, one characterized by the presence of +10, a second by +17 and +3q, and a third by +16, +20, and +12.