37P - Nischarin can be a target for stromal normalisation in pancreatic ductal adenocarcinoma

Background

Nischarin (NISCH) is a scaffolding protein involved in the control of cytoskeletal dynamics. Its tumor suppressive role has been demonstrated in breast cancer; and high expression in tumor tissue was reported as a positive prognostic marker in breast and ovarian cancers. Of interest, there are several approved nischarin agonists used in treatment of hypertension. We have previously found that NISCH is expressed in both tumor cells and cancer-associated fibroblasts (CAFs) in pancreatic ductal adenocarcinoma (PDAC) and that nischarin agonist rilmenidine can limit cancer cell invasion. As the dense tumor stroma makes up to 80% of the bulk tumor tissue in PDAC, and is one of the causes of current treatment failure, the aim of this study was to examine the effects of nischarin agonists on the phenotype of cancer-associated stroma in PDAC.

Methods

NISCH expression and co-localization with CAF markers were examined by immunohistochemistry in PDAC tissue microarray. CAFs were isolated from fresh tumor tissue by the outgrowth method. MTT test was used to evaluate cytotoxicity of nischarin agonist rilmenidine on patient-derived CAFs. Immunoblotting, immunocytochemistry, ELISA and qRT-PCR were used to examine the effects of rilmenidine treatment on the extracellular matrix deposition and cytokine and growth factor production in CAFs and ex vivo cultures of PDAC tumor tissue.

Results

Nischarin was expressed in both aSMA⁺ and FAP⁺ cells in the tumor tissue. Patient-derived CAFs were a heterogeneous population, positive for aSMA⁺ FAP⁺, collagen I and fibronectin. Rilmenidine treatment of patient-derived CAFs in vitro was not cytotoxic at concentrations achievable in the human plasma. Nevertheless, rilmenidine treatment decreased fractions of both aSMA⁺ and FAP⁺ cells in vitro and decreased the production of pro-inflammatory cytokines IL-6, IL-8 and CCL-2. Treatment of ex vivo PDAC tumor cultures for 72h remodeled the extracellular matrix.

Conclusions

Our results imply that rilmenidine treatment in vitro and ex vivo shows a potential for normalizing PDAC tumor-derived CAFs and may be a good candidate for drug repurposing.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

European Research Executive Agency; Science Fund of the Republic of Serbia.

Disclosure

All authors have declared no conflicts of interest.