Diabetic retinopathy (DR) is reaching epidemic levels globally due to the increase in prevalence of diabetes mellitus (DM). DR also has detrimental effects to quality of life, as it is the leading cause of blindness in the working-age population and the most common cause of vision loss in individuals with DM. Over several decades, many studies have recognized the role of inflammation in the development and progression of DR; however, in recent years, accumulating evidence has also suggested that non-coding RNAs, especially long non-coding (lncRNAs), are aberrantly expressed in diabetes and may play a putative role in the development and progression of DR through the modulation of gene expression at the transcriptional, post-transcriptional, or epigenetic level. In this review, we will first highlight some of the key inflammatory mediators and transcription factors involved in DR, and we will then introduce the critical roles of lncRNAs in DR and inflammation. Following this, we will discuss the implications of lncRNAs in other epigenetic mechanisms that may also contribute to the progression of inflammation in DR.

Metastasis is present in approximately 30% of patients diagnosed with renal cell carcinoma (RCC) and is associated with a 5-year survival rate of < 15%. Kidney injury molecule 1 (KIM-1), encoded by the HAVCR1 gene, is a proximal tubule cell-surface glycoprotein and a biomarker for early detection of RCC, but its pathophysiological significance in RCC remains unclear. We generated human and murine RCC cell lines either expressing or lacking KIM-1, respectively, and compared their growth and metastatic properties using validated methods. Surprisingly, KIM-1 expression had no effect on cell proliferation or subcutaneous tumour growth in immune deficient (Rag1−/−) Balb/c mice, but inhibited cell invasion and formation of lung metastasis in the same model. Further, we show that the inhibitory effect of KIM-1 on metastases was observed in both immune deficient and immune competent mice. Transcriptomic profiling identified the mRNA for the pro-metastatic GTPase, Rab27b, to be downregulated significantly in KIM-1 expressing human and murine RCC cells. Finally, analysis of The Cancer Genome Atlas (TCGA) data revealed that elevated HAVCR1 mRNA expression in the two most common types of RCC, clear cell and papillary RCC, tumours correlated with significantly improved overall patient survival. Our findings reveal a novel role for KIM-1 in inhibiting metastasis of RCC and suggests that tumour-associated KIM-1 expression may be a favourable prognostic factor.

Renal cell carcinoma (RCC) is the most common and lethal form of kidney cancer. Cancer immune evasion is a major obstacle for effective immunotherapy in RCC. Mechanisms of immune evasion are characterized by three phenotypes: Immune Inflamed; tumor contains infiltrating T cells which are rendered inactive within the tumor microenvironment due to localized inhibition. Immune Desert; tumor is devoid of activate T cells due to defective antigen presentation, and/or T cell activation. Lastly, Immune Excluded; tumor is surrounded by T cells that are unable to penetrate the parenchyma, caused by immunosuppression within the tumor stroma. Kidney Injury Molecule-1 (KIM-1) is a cell-surface glycoprotein aberrantly expressed in &gt;90% of RCC tumors. The purpose of this study was to determine the pathophysiological significance of KIM-1 in RCC pathogenesis. We generated murine RCC cells (Renca) expressing KIM-1 (KIM-1pos) or control vector (KIM-1neg) using lentiviral transduction. We found that KIM-1 expression on RCC cells promoted more rapid tumor growth when injected contralaterally into syngeneic immunocompetent BALB/c mice (KIM-1neg = 263.75mm3, KIM-1pos = 849.72, p = 0.0149 & KIM-1neg = 0.32g, KIM-1pos = 0.58, p = 0.0229), but not in RAG1-/- immunodeficient BALB/c mice suggesting the KIM-1 promotes tumor growth through evasion of the adapt immune system. When analyzing tumor infiltrating lymphocytes (TILs) from both tumor groups, we found a relative scarcity of CD4+ and CD8+ T cells within the KIM-1pos vs. KIM-1neg tumors. To classify the immune evasion phenotype, we analyzed localization of the immune infiltrate using immunofluorescence within KIM-1pos and KIM-1neg RCC tumors. We found significantly fewer CD3+ cells within the KIM-1pos vs. KIM-1neg tumor parenchyma (KIM-1neg = 3625.78%, KIM-1pos = 272.36%, p = 0.0410). Moreover, CD3+ cells of the KIM-1neg tumors were observed in the parenchyma, whereas CD3+ cells of the KIM-1pos tumors were localized to the tumor stroma. In addition, we observed a higher frequency of myeloid derived suppressor cells (MDSCs) within the KIM-1pos vs the KIM-1neg tumor parenchyma (KIM-1neg = 0.05, KIM-1pos = 0.19, p = 0.0266). Transcriptomic profiling of both KIM-1pos and KIM-1neg Renca cells suggests that KIM-1 promotes deposition of extracellular matrix (KIM-1neg = -1.21, KIM-1pos = 1.96-fold change), which may contribute to KIM-1-mediated immune evasion Our data suggests that KIM-1 expression in RCC promotes immune evasion by altering the tumor microenvironment resulting in an Immune Excluded phenotype. Citation Format: Demitra M. Yotis, Bradly Shrum, Marie Sarabusky, Lakshman Gunaratnam. KIM–1 mediatesimmune evasioninrenal cell carcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2162.

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 &gt;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.