Abstract 4922: Microscale engineering of the tumor microenvironment for therapeutic targeting of tumor-associated macrophages in prostate cancer
Authors: Kosoff David , Yu Jiaquan , Schehr Jennifer L. , Beebe David J. , Lang Joshua M. 
Published: July 2017

Abstract
Background
The tumor microenvironment (TME) plays integral roles in prostate cancer progression and therapeutic resistance. The development of effective TME-targeted therapies is limited by current technologies which are insufficient to replicate or analyze this complex environment. To address these challenges, we have developed a microfluidic cell culture platform known as STACKS, which permits co-culture of up to 6 patient-derived cell populations as well as compartmentalized, multiplexed analysis of gene expression, cell signaling, and matrix remodeling. We have focused on investigation of tumor-associated macrophages (TAMs), which are traditionally classified as M2 (tumor-supportive) or M1 (tumor-destructive) and are high value therapeutic targets with roles in prostate cancer growth, metastasis, survival, and therapeutic resistance.
Methods
Cell line (THP-1) and patient-derived monocytes were differentiated into macrophages within the STACKs device and polarized to either a M1 or M2 state or left unpolarized. Unpolarized macrophages were cultured with androgen dependent (LNCaP) and independent (DU145,C4-2B) prostate tumor lines and cancer-associated fibroblasts (CAFs) derived from patient biopsies. Cells were cultured on 2D surfaces as well as within 3D matrix environments. Individual cell populations were isolated and analyzed for RNA, protein, and secretory factor expression.
Results
We report that M2 (CCL18, MRC1) as well as M1 (CXCL10, CXCL11) associated genes were more highly upregulated in THP-1s cultured with C4-2Bs than with LNCaPs. Select M1 and M2 genes (CXCL10 and CCL18) were also more highly expressed in THP-1s cultured with CAFs than with DU145s. While IL-10 expression was higher in THP-1s in co-culture with LNCaPs than with C4-2Bs on a 2D surface, the opposite was true when THP-1s were cultured within a 3D collagen I matrix.
Conclusions
Within a microscale co-culture environment, we have demonstrated that macrophage gene expression is influenced by androgen dependent and independent tumor cells, stromal cells, and the structural microenvironment. Expression of certain genes, such as IL-10, was strongly dependent on the integration of multiple TME signals, such as paracrine tumor factors and cell-matrix interactions. Additionally, while macrophages are traditionally thought to polarize either towards a M1 or a M2 state, there was concomitant elevation of both M1 and M2 genes with C4-2B and CAF co-culture. These findings highlight the complexity of macrophage polarization within the TME and represent potential therapeutic targets. We will continue to build on this data through 2D and 3D multi-culture of macrophages with tumor, stromal, and immune cells to target pathways involved in TAM polarization, tumor promotion, and therapeutic resistance.
Citation Format: David Kosoff, Jiaquan Yu, Jennifer L. Schehr, David J. Beebe, Joshua M. Lang. Microscale engineering of the tumor microenvironment for therapeutic targeting of tumor-associated macrophages in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4922. doi:10.1158/1538-7445.AM2017-4922