Description: Purpose: Pancreatic cancer is characterized by stromal desmoplasia and perineural invasion (PNI). We sought to explore the contribution of pancreatic stellate cells (PSC) activated by paracrine Sonic Hedgehog (SHH) in pancreatic cancer PNI and progression. Experimental Design: In this study, the expression dynamics of SHH were examined via immunohistochemistry, real-time PCR, and Western blot analysis in a cohort of carcinomatous and nonneoplastic pancreatic tissues and cells. A series of in vivo and in vitro assays was performed to elucidate the contribution of PSCs activated by paracrine SHH signaling in pancreatic cancer PNI and progression. Results: We show that SHH overexpression in tumor cells is involved in PNI in pancreatic cancer and is an important marker of biologic activity of pancreatic cancer. Moreover, the overexpression of SHH in tumor cells activates the hedgehog pathway in PSCs in the stroma instead of activating tumor cells. These activated PSCs are essential for the promotion of pancreatic cancer cell migration along nerve axons and nerve outgrowth to pancreatic cancer cell colonies in an in vitro three-dimensional model of nerve invasion in cancer. Furthermore, the coimplantation of PSCs activated by paracrine SHH induced tumor cell invasion of the trunk and nerve dysfunction along sciatic nerves and also promoted orthotropic xenograft tumor growth, metastasis, and PNI in in vivo models. Conclusions: These results establish that stromal PSCs activated by SHH paracrine signaling in pancreatic cancer cells secrete high levels of PNI-associated molecules to promote PNI in pancreatic cancer. Clin Cancer Res; 20(16); 4326–38. ©2014 AACR .

Description: Although it is now widely appreciated that antitumor immunity is critical to impede tumor growth and progression, there remain significant gaps in knowledge about the mechanisms used by tumors to escape immune control. In tumor cells, we hypothesized that one mechanism of immune escape used by tumors involves the synthesis and extracellular shedding of gangliosides, a class of biologically active cell surface glycosphingolipids with known immunosuppressive properties. In this study, we report that tumor cells engineered to be ganglioside deficient exhibit impaired tumorigenicity, supporting a link between ganglioside-dependent immune escape and tumor outgrowth. Notably, we documented a dramatic reduction in the numbers and function of tumor-infiltrating myeloid-derived suppressor cells (MDSC) in ganglioside-deficient tumors, in contrast with the large MDSC infiltrates seen in ganglioside-rich littermate control tumors. Transient ganglioside reconstitution of the tumor cell inoculum was sufficient to increase MDSC infiltration, supporting a direct connection between ganglioside production by tumor cells and the recruitment of immunosuppressive MDSC into the tumor microenvironment. Our results reveal a novel mechanism of immune escape that supports tumor growth, with broad implications given that many human tumors produce and shed high levels of gangliosides. Cancer Res; 74(19); 5449–57. ©2014 AACR.

Description: The drug efflux transporter ABCB5 identifies cancer stem–like cells (CSC) in diverse human malignancies, where its expression is associated with clinical disease progression and tumor recurrence. ABCB5 confers therapeutic resistance, but other functions in tumorigenesis independent of drug efflux have not been described that might help explain why it is so broadly overexpressed in human cancer. Here we show that in melanoma-initiating cells, ABCB5 controls IL1β secretion, which serves to maintain slow cycling, chemoresistant cells through an IL1β/IL8/CXCR1 cytokine signaling circuit. This CSC maintenance circuit involved reciprocal paracrine interactions with ABCB5-negative cancer cell populations. ABCB5 blockade induced cellular differentiation, reversed resistance to multiple chemotherapeutic agents, and impaired tumor growth in vivo. Together, our results defined a novel function for ABCB5 in CSC maintenance and tumor growth. Cancer Res; 74(15); 4196–207. ©2014 AACR.