Abstract 4604: Kidney injury molecule-1 regulates metastasis in renal cell carcinoma

Abstract

Abstract Over 30% of patients with renal cell carcinoma (RCC) present with metastases, with median survival of 2 years. Kidney injury molecule 1 (KIM-1) is a cell-surface glycoprotein expressed by >85% of RCC tumours and may serve as an early biomarker for RCC detection. Here we sought to determine if tumour KIM-1 plays a role in RCC cell extravasation and metastasis to lungs. Methods: We overexpressed KIM-1 in Renca cells (murine RCC) using stable transfection of an expression plasmid, or silenced endogenous KIM-1 in human 769-P and 786-O RCC cells using shRNA. We studied extravasation using the chorioallantoic membrane (CAM) model. We injected ~1x105 Renca or 769-P cells into blood vessels of chicken embryos (n=6), and measured percentage of cells that exited the capillary bed into surrounding spaces after 24 hours. To study lung metastasis, we injected ~5x105 Renca or 786-O cells intravenously through the tail vein of syngeneic BALB/c (n=10/group) or immune deficient Rag1-/- [BALB/c] (n=5/group) mice, and manually counted metastatic nodules in excised lungs after 17 days. Finally, we analyzed the publicly available Cancer Genome Atlas Illumina RNA-Seq dataset to determine if KIM-1 mRNA expression predicts overall survival in patients with clear cell RCC. Results: In CAM experiments, extravasation efficiency was significantly decreased in KIM-1pos 769-P cells compared to KIM-1neg 769-P cells (30.08% vs. 47.94%; p=0.0004), and in KIM-1pos Renca cells compared to KIM-1neg Renca cells (47.78% vs 60.73%; p=0.042). BALB/c mice injected with Kim-1pos Renca cells or Kim-1pos 786-O cells had significantly fewer lung metastases compared to mice injected with Kim-1neg Renca cells or Kim-1neg 786-O cells, respectively (257 vs 429, p=0.02; 131 vs 339 p=0.001). The inhibitory effect of KIM-1 expression in Renca and 786-O cells on numbers of lung metastases was similar in Rag1-/- mice, suggesting that the observed effects were not dependent on adaptive immunity. In the TCGA database, patients with the lowest vs. highest tertile of KIM-1 RCC expression has significantly higher mortality (unadjusted HR 1.82, 95% CI 1.23-2.70; p=0.0034). Conclusion: KIM-1 is a negative regulator of cell extravasation and inhibits the development of lung metastases in mice, and KIM-1 expression in human RCC may predict better survival. Deciphering the underlying mechanisms may lead to novel therapies. Citation Format: Jasper C. Lee, Marie A. Sarabusky, Audrey Champagne, Fabrice Lucien, Lakshman Gunaratnam. Kidney injury molecule-1 regulates metastasis in renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4604.