We demonstrated that the CellCollector is an appropriate tool for detecting CTCs in RCC patients. We examined EpCAM and MUC1 expression levels in RCC tissues and cell lines and analyzed the detection ...rate of CTCs in blood samples ex vivo using an anti-EpCAM antibody-covered straight or spiraled CellCollector. Eight matched samples were examined for affinity to the anti-EpCAM vs. anti-EpCAM/anti-MUC1 antibody-covered wire. The use of this combination of antibodies allowed us to classify patients with lung metastasis. Finally, four patients were analyzed in vivo. In conclusion, both straight (ex vivo, in vivo) and spiraled (ex vivo) wires detected CTCs.
The expression and cellular mechanisms of programmed cell death-1 protein (PD-1) and its ligands (PD-L1 and PD-L2) in renal cancer cells are not well known. Here, we aimed to investigate the response ...of renal carcinoma subtypes to the immune checkpoint inhibitor nivolumab and its impact on related signaling pathways. All cell lines analyzed (clear cell (cc)RCC (Caki-1, RCC31) and papillary (p)RCC (ACHN, RCC30)) expressed PD-1 and both ccRCC cell lines, and RCC30 expressed PD-L1. Nivolumab treatment at increasing doses led to increased PD-1 levels in analyzed cells and resulted in aggressive behavior of pRCC but diminished this behavior in ccRCC. The analysis of PD-1/PD-L1-associated signaling pathways demonstrated increased AKT activity in Caki-1 and RCC30 cells but decreased activity in ACHN and RCC31 cells, while ribosomal protein S6 remained largely unchanged. Androgen receptors are related to RCC and were predominantly increased in RCC30 cells, which were the only cells that formed nivolumab-dependent spheroids. Finally, all cell lines exhibited a complex response to nivolumab treatment. Since the pRCC cells responded with increased tumorigenicity and PD-1/PD-L1 levels while ccRCC tumorigenicity was diminished, further studies are needed to improve nivolumab-based therapy for renal carcinoma subtypes, especially the identification of response-involved molecular pathways.
Abstract Introduction: Renal cell carcinoma (RCC) belongs to the most invasive cancers with the high molecular intrapatient heterogeneity. Circulating tumor cells (CTCs) are cells that detach from ...the tumor, reflecting the activity of the metastatic procedure. The most popular CTCs isolation methods are based on EpCAM signal detection on epithelial tumor cells. The clear cell RCC (ccRCC) originate from epithelial entity, since that is the EpCAM-based method suitable to isolate CTCs in this cancer. However, the prone of CTCs to EMT is known, which may in consequence downregulate the EpCAM expression and change the cell profile (hybrid phenotype). This is one of the points challenging the CTCs isolation by RCC disease. In our study, we compare the effectivity of antibody-based and density-based isolations technics in ccRCC patients to detect potential markers in CTCs. Purpose: Our aim was to find a precise and costs effective method to isolate and characterize CTCs from ccRCC patients. Materials and Methods: Prospective blood samples (3mL) from pulmonary and/or osseous metastatic ccRCC patients were collected during the immunotherapy and from the healthy donors. CTCs were isolated using EpCAM beads (RCC n=13; healthy n=15) or density-based (RCC n=13; healthy n=15) method. Expression of potential RCC biomarkers (mucin-1 (Muc1), androgen receptor (AR)) was identified using qPCR (Real-Time PCR) followed by dPCR (digital PCR), the results status received from both methods was evaluated. Summary: Based on our prior results, we first isolated CTCs based on EpCAM beads. Using qPCR we analyzed expression of genes, which we previously associated to the RCC (Muc1, PD-L1, AR). The results revealed differences in Muc1 (40% of tested patients positive but none of the healthy donors), when PD-L1 did not differed and AR was not detected. Applying more precise dPCR did neither show any expression. We continued our investigations with isolation of CTCs using density-based method. We confirmed more frequent expression of Muc1 by RCC Patients than by donors, as in our EpCAM cohort. PD-L1 was similar in both groups. Results of AR obtained using qPCR were confusing, showing deviations within same patients. The use of dPCR displayed significant differences in expression between RCC patients (77%; median range 0.28 0.00 - 0.62 and donors (60%; 0.04 0.00 - 0.51 confirming dPCR as optimal tool for molecular CTC characterization. Conclusions: Based on our results we demonstrate higher expression of Muc1 and AR in CTCs of metastatic ccRCC patients. The isolation technic should be adapted to the disease status and treatment choice. Further investigations confirming Muc1 and AR as ccRCC biomarkers are required. Citation Format: Joanna Bialek, Anne Muthe, Stefan Yankulov, Felix Kawan, Georgios Gakis, Gerit Theil. Optimizing CTC isolation techniques for molecular characterization of circulating tumor cells in clear cell renal cell carcinoma: A comparative study of EpCAM-based and density-based methods abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3689.
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