Aim of the study was to isolate and characterize tumor initiating cells from renal cell cancer tumor samples and stable cell lines.
Primary and metastatic RCC cell lines were used in the study including Caki-1, Caki-2, 786-0, ACHN, 769-P, SMKT-R2, SMKT-R3. Human kidney cancer stem cells (HKCSCs) isolated from primary tumor tisses were coultured in non-differentating conditions. Cells were cultured in 2D and 3D. Normal proximal tube cells (PSC-400) were used as control. Fluorescence Activated Cell Sorting (FACS) and immunihistochemistry were used to investigate renal, mesenchymal and stem cell markers: CD10, CD11b, CD19, CD31, CD34, CD24, CD44, CD45, CD146, CD90, CD73, CD44, CD105, CD133, HLA-DR, ALP, ALHDH1, CK7. Soft agar clonogenic assay/colony formation assay were conducted to evaluate clonogenic potential of cells. Cell sorting was used to isolate RCC-CD105(+) cells - subpopulation known as tumor initiating cells in papillary and clear cell RCC. Total RNA was extracted from CD105+ cells, reverse-transcription was conducted and cDNA was used for analysis with Agilent Human Gene Expression 4x44K Microarray. Mas spectometry was used to differentiate between drug resistant and pre-treatment cells in different oxygenation micro-environment. VHL and cMET mutation were verified by DNA sequencing.
Tumor initiating cell subpopulations were found in primary and metastatic cell lines. Higher number of stem cell phenotype cells is found in metastatic cases and papillary cancer. Cancer stem-line cells in RCC phenotype is defined by overexpresson of CD90, CD73, CD44, CD105, CD133. Stem cell phenotype is not stable in time and abundance of such cells is case specific. Stem-like cells derived from metastatic cases are characterized by specific panel of up-regulated genes in comparison to primary tumor tissue and normal renal proximal tube cells.
Tumor initiating cells may be a promising target for novel therapies in renal cell cancer. Novel therapies base on monoclonal antibodies could be considered for pre-clinical and clinical development.
Clinical trial identification
Not a clinical trail.
All authors have declared no conflicts of interest.