Abstract 3513: Developing a 3D biomimetic liver metastatic niche model for pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is the 3rd leading cause of cancer death in the Unites States with a 5-year survival rate of only 11%. Early diagnosis is very difficult and thus 53% of patients are diagnosed after metastasis has already occurred, with the liver being the most frequently affected site. Both primary tumors and metastases have highly fibrotic stroma. Thus, stromal targeting agents have the potential to benefit patients, even those with metastatic disease. However, in addition to different resident fibroblasts, a study based on a rapid autopsy program of metastatic PDAC patients showed that tumor ECM density is actually lower at sites of liver metastasis compared to the primary tumor. These results highlight some of the differences between the microenvironment of the liver metastatic niche (LMN) compared to that of the primary tumor. Thus, to best help patients, models which recapitulate the LMN are needed. We developed a 3D biomimetic model to co-culture PDAC organoids and host matching primary CAFs to recapitulate the desmoplastic environment of primary PDAC. Our preliminary results show that primary site derived CAFs induce organoid growth, chemoresistance, and ECM remodeling when co-cultured with PDAC organoids. Utilizing paired organoids which metastasized to the liver (LM organoids), we tested if primary site derived CAFs would have the same effect on LMs. Interestingly, we observed that while LM organoids were intrinsically more drug resistant, co-culture with primary site derived CAFs had no effect on chemoresistance or ECM remodeling. Next, we utilized a metastasis associated fibroblast (MAF) liver cell line to investigate the role of MAFs in tumor growth, chemoresistance, and ECM remodeling. Our results show that primary and metastatic organoids use different mechanism to induce ECM stiffness triggered by fibroblast activation and remodeling in their resident fibroblasts.

Citation Format: Mahsa Pahlavanneshan, Weikun Xiao, Chae Young Eun, Chang-Il Hwang, Reginald Hill. Developing a 3D biomimetic liver metastatic niche model for pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3513.

Abstract 6414: Using 3D models to test the efficacy of targeting cancer-associated fibroblast exosomes to overcome chemoresistance in pancreatic cancer

Exosomes play a critical role in promoting proliferation and survival of cancer cells. These extracellular vesicles that range in size from 30-100nm in diameter are released by many different cell types and contain proteins, nucleic acids, and micro RNAs that can modify the content and state of recipient cells. Our previous studies have shown that cancer-associated fibroblasts (CAFs), which make up the bulk of pancreatic ductal adenocarcinoma (PDAC) tumors, hypersecrete exosomes upon chemotherapy treatment. When these exosomes were taken up by surrounding cancer cells, we observed more cell proliferation and drug resistance. Considering these findings, there is clearly a need of therapeutic strategies that target exosome biogenesis and secretion. Here, we investigate the effectiveness of several compounds, including farnesyl transferase inhibitors, imidazoles, and nonsteroidal anti-inflammatory drugs (NSAIDs), in blocking exosome secretion and suppressing chemoresistance in PDAC CAF and cancer cell lines. We observed decrease in exosome secretion upon ketoconazole, tipifarnib, and neticonazole treatment, using GW4869 (a neutral sphingomyelinase inhibitor) as our control. Furthermore, we established a 3D organoid model from our PDAC mouse models to better understand the impact of these drugs on exosome secretion in tumors with different genetic alterations. Together, our 2D and 3D models illuminate the potential for pharmacological targeting of exosome secretion as a treatment option that can improve the current standard-of-care treatment in PDAC.

Citation Format: Chae Young Eun, Charlene DeKalb, Weikun Xiao, Xinyu Zhang, Reginald Hill. Using 3D models to test the efficacy of targeting cancer-associated fibroblast exosomes to overcome chemoresistance in pancreatic cancer [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 6414.