Distinct populations of inflammatory fibroblasts and myofibroblasts in pancreatic cancer

Pancreatic stellate cells (PSCs) differentiate into cancer-associated fibroblasts (CAFs) that produce desmoplastic stroma, thereby modulating disease progression and therapeutic response in pancreatic ductal adenocarcinoma (PDA). However, it is unknown whether CAFs uniformly carry out these tasks or if subtypes of CAFs with distinct phenotypes in PDA exist. We identified a CAF subpopulation with elevated expression of alpha-smooth muscle actin (alphaSMA) located immediately adjacent to neoplastic cells in mouse and human PDA tissue. We recapitulated this finding in co-cultures of murine PSCs and PDA organoids, and demonstrated that organoid-activated CAFs produced desmoplastic stroma. The co-cultures showed cooperative interactions and revealed another distinct subpopulation of CAFs, located more distantly from neoplastic cells, which lacked elevated alphaSMA expression and instead secreted IL6 and additional inflammatory mediators. These findings were corroborated in mouse and human PDA tissue, providing direct evidence for CAF heterogeneity in PDA tumor biology with implications for disease etiology and therapeutic development

Pancreatic stellate cell heterogeneity in cancer

Introduction: Paracrine interactions between pancreatic stellate cells (PSCs) and tumor cells play key roles in pancreatic cancer tumorigenesis. However attempts to therapeutically target the PSCs have led to contradictory results, raising the possibility of diverse pathophysiological roles of these cells. Aims: The aim of this project is to gain a deeper understanding of the functional heterogeneity found in PSCs. Materials & methods: We have developed an organotypic co-culture system that allows us to study the interactions between tumor-derived organoids and PSCs in a three-dimensional matrix (Matrigel). Murine and human tissues have been used to validate our findings. Results: PSCs embedded in Matrigel acquire a quiescent phenotype, but become highly proliferative when co-cultured with tumor cells and differentiate into two distinct subtypes showing different phenotypic features. PSCs found in direct contact with tumor cells express smooth muscle actin (SMA), while PSCs that are more distant from the tumor cells show low SMA expression and gain a secretory phenotype. The secreted factors from this subtype of PSCs can activate certain pathways in tumor organoids important for proliferation and survival. We also show that these two subtypes are mutually exclusive and can both be found in vivo with similar spacial distribution as seen in the co-culture system. Conclusion: We have identified two subtypes of PSCs present in pancreatic cancer with potentially different pathophysiological functions. We believe that the outcome of trials targeting the PSCs will depend on which subtype that is preferentially affected by the treatment

Synergistic combination therapy delivered via layer‐by‐layer nanoparticles induces solid tumor regression of ovarian cancer

Abstract The majority of patients with high grade serous ovarian cancer (HGSOC) develop recurrent disease and chemotherapy resistance. To identify drug combinations that would be effective in treatment of chemotherapy resistant disease, we examined the efficacy of drug combinations that target the three antiapoptotic proteins most commonly expressed in HGSOC—BCL2, BCL‐XL, and MCL1. Co‐inhibition of BCL2 and BCL‐XL (ABT‐263) with inhibition of MCL1 (S63845) induces potent synergistic cytotoxicity in multiple HGSOC models. Since this drug combination is predicted to be toxic to patients due to the known clinical morbidities of each drug, we developed layer‐by‐layer nanoparticles (LbL NPs) that co‐encapsulate these inhibitors in order to target HGSOC tumor cells and reduce systemic toxicities. We show that the LbL NPs can be designed to have high association with specific ovarian tumor cell types targeted in these studies, thus enabling a more selective uptake when delivered via intraperitoneal injection. Treatment with these LbL NPs displayed better potency than free drugs in vitro and resulted in near‐complete elimination of solid tumor metastases of ovarian cancer xenografts. Thus, these results support the exploration of LbL NPs as a strategy to deliver potent drug combinations to recurrent HGSOC. While these findings are described for co‐encapsulation of a BCL2/XL and a MCL1 inhibitor, the modular nature of LbL assembly provides flexibility in the range of therapies that can be incorporated, making LbL NPs an adaptable vehicle for delivery of additional combinations of pathway inhibitors and other oncology drugs

Organoid Models of Human and Mouse Ductal Pancreatic Cancer

Summary Pancreatic cancer is one of the most lethal malignancies due to its late diagnosis and limited response to treatment. Tractable methods to identify and interrogate pathways involved in pancreatic tumorigenesis are urgently needed. We established organoid models from normal and neoplastic murine and human pancreas tissues. Pancreatic organoids can be rapidly generated from resected tumors and biopsies, survive cryopreservation, and exhibit ductal- and disease-stage-specific characteristics. Orthotopically transplanted neoplastic organoids recapitulate the full spectrum of tumor development by forming early-grade neoplasms that progress to locally invasive and metastatic carcinomas. Due to their ability to be genetically manipulated, organoids are a platform to probe genetic cooperation. Comprehensive transcriptional and proteomic analyses of murine pancreatic organoids revealed genes and pathways altered during disease progression. The confirmation of many of these protein changes in human tissues demonstrates that organoids are a facile model system to discover characteristics of this deadly malignancy