NK cell-mediated targeting of cancer cells that have undergone the epithelial to mesenchymal transition to overcome metastasis in pancreatic cancer

Abstract public domain (NIH RePORTER)

Project Summary: About 75% of pancreatic cancer patients relapse after surgery. Most start chemotherapy but cannot complete the recommended regimens due to its toxicity, allowing the remaining cancer cells to form fatal metastases in the liver, lungs, or peritoneum. Therefore, there is an urgent need for a therapy that has a lower toxicity profile than chemotherapy and that specifically targets metastasizing cancer cells. The epithelial to mesenchymal transition (EMT) drives metastasis by enabling cancer cell migration. This process is not simply binary: carcinoma cells can become hybrid epithelial-mesenchymal (EM) cells, which are highly invasive and alter the tumor immune microenvironment by reducing CD8+ T cell infiltration. EMT occurs early in pancreatic cancer, affecting the immune environment even before metastasis. Downregulation of MHC class I in pancreatic cancer also diminishes the effectiveness of CD8+ T cells, but natural killer (NK) cells thrive in such conditions and kill these tumor cells. Remarkably, NK cells infiltrate EMT-enriched tumors more efficiently than CD8+ T cells. Given their low toxicity profiles, NK cell-based therapies are promising candidates for targeting hybrid EM cells. To study the interplay between NK cells and cancer cells across the EMT spectrum, I have developed and validated a doxycycline-inducible system that allows induction of epithelial or mesenchymal phenotypes in hybrid EM cells through the expression of miR-200c, which promotes epithelial properties, or Zeb-1, which results in the acquisition of mesenchymal properties. Preliminary data indicate that NK cells exhibit reduced cytotoxicity against hybrid EM cells compared to their epithelial counterparts. Accordingly, I hypothesize that hybrid EM pancreatic cancer cells are resistant to NK cell killing via inhibitory receptor-ligand pairs that can be targeted to promote hybrid EM clearance. In Aim 1, I will study how EMT in cancer cells influences their recognition by NK cells. The sensitivity of epithelial, hybrid EM, and mesenchymal cancer cells to NK cell killing will be assessed, and the NK cell phenotype will be gauged for exhaustion markers and the expression of both activating and inhibitory receptors. In Aim 2, I will investigate how pancreatic cancer cells suppress NK cell function, focusing on reduced MHC class I in miR-200c-induced cells and the potential of targeting the LIR- 1:MHC-I axis. After injecting different murine cancer cell types into mice, I will analyze the transcriptomics of metastases and perform receptor-ligand analysis. Receptors preventing NK cell killing of hybrid EM cells will be blocked in vitro and in vivo with an antibody-mediated blockade to clear these cells and prevent metastasis. This F31 fellowship will allow me to decipher the interaction between hybrid EM cancer cells and NK cells, which could lead to the development of targeted, low-toxicity therapies for pancreatic cancer patients. With the success of my proposed research and the environment put together by Dr. Mani, I will be fully prepared for post-doctoral research and further scientific independence, allowing me to eventually establish my own laboratory.

Public health relevance public domain (NIH RePORTER)

Project Narrative: Patients who undergo surgical resection for pancreatic cancer often relapse due to the ability of cancer cells to metastasize and the ineffectiveness of chemotherapy. Given that activation of the epithelial-mesenchymal transition and the resulting hybrid epithelial-mesenchymal cancer cells appear to drive this phenomenon, there is an urgent need for a therapy that can be tolerated by patients and specifically targets the metastasizing cancer cells with hybrid properties. I propose to determine how cancer cells on the epithelial-mesenchymal spectrum influence natural killer cell activity and to develop strategies to enhance natural killer cell-mediated clearance of metastasizing cells.