ObjectivesThree-dimensional organoids derived from primary pancreatic ductal adenocarcinomas are an attractive platform for testing potential anticancer drugs on patient-specific tissue. Optical metabolic imaging (OMI) is a novel tool used to assess drug-induced changes in cellular metabolism, and its quantitative end point, the OMI index, is evaluated as a biomarker of drug response in pancreatic cancer organoids.MethodsOptical metabolic imaging is used to assess both malignant cell and fibroblast drug response within primary murine and human pancreatic cancer organoids.ResultsAnticancer drugs induce significant reductions in the OMI index of murine and human pancreatic cancer organoids. Subpopulation analysis of OMI data revealed heterogeneous drug response and elucidated responding and nonresponding cell populations for a 7-day time course. Optical metabolic imaging index significantly correlates with immunofluorescence detection of cell proliferation and cell death.ConclusionsOptical metabolic imaging of primary pancreatic ductal adenocarcinoma organoids is highly sensitive to drug-induced metabolic changes, provides a nondestructive method for monitoring dynamic drug response, and presents a novel platform for patient-specific drug testing and drug development.

BACKGROUND & AIMS A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the presence of a dense desmoplastic reaction (stroma) that impedes drug delivery to the tumor. Attempts to deplete the tumor stroma have resulted in formation of more aggressive tumors. We have identified STAT3 as a biomarker of resistance to cytotoxic and molecularly targeted therapy in PDAC. The purpose of this study is to investigate the effects of targeting STAT3 on the PDAC stroma and on therapeutic resistance. METHODS Activated STAT3 protein expression was determined in human pancreatic tissues and tumor cell lines. In vivo effects of AZD1480, a JAK/STAT3 inhibitor, gemcitabine or the combination were determined in Ptf1acre/+;LSL-KrasG12D/+;Tgfbr2flox/flox (PKT) mice and in orthotopic tumor xenografts. Drug delivery was analyzed by MALDI-imaging mass spectrometry. Collagen second harmonic generation (SHG) imaging quantified tumor collagen alignment and density. RESULTS STAT3 activation correlates with decreased survival and advanced tumor stage in patients with PDAC. STAT3 inhibition combined with gemcitabine significantly inhibits tumor growth in both an orthotopic and the PKT mouse model of PDAC. This combined therapy attenuates in vivo expression of SPARC, increases microvessel density and enhances drug delivery to the tumor without depletion of stromal collagen or hyaluronan. Instead, the PDAC tumors demonstrate vascular normalization, remodeling of the tumor stroma and downregulation of cytidine deaminase (Cda). CONCLUSIONS Targeted inhibition of STAT3 combined with gemcitabine enhances in vivo drug delivery and therapeutic response in PDAC. These effects occur through tumor stromal remodeling and downregulation of Cda without depletion of tumor stromal content.

Secondary bile acids (BAs) such as deoxycholic acid (DCA) promote the development of several gastrointestinal malignancies, but how they mediate this effect is unclear. In this study, we offer evidence of a mechanism involving ectodomain shedding of the EGFR ligands amphiregulin (AREG) and TGF-α which rely upon the cell surface protease TACE/ADAM-17. Specifically, we show that AREG participates in DCA-induced EGFR and STAT3 signaling, cell cycle progression and tumorigenicity in human colorectal cancer (CRC) and pancreatic ductal adenocarcinoma (PDAC). TACE and AREG, but not TGF-α, were overexpressed in both CRC and PDAC tissues compared to normal tissues. Exposure of CRC and PDAC cells to DCA resulted in co-localization of Src and TACE to the cell membrane, resulting in AREG-dependent activation of EGFR, MAPK and STAT3 signaling. Src or TACE inhibition was sufficient to attenuate DCA-induced AREG, but not TGF-α shedding. We also examined a role for the bile acid transporter TGR5 in DCA-mediated EGFR and STAT3 signaling. RNAi-mediated silencing of TGR5 or AREG inhibited DCA-induced EGFR, MAPK and STAT3 signaling, blunted cyclin D1 expression and cell cycle progression, and attenuated DCA-induced CRC or PDAC tumorigenicity. Together, our findings define an AREG-dependent signaling pathway that mediates the oncogenic effects of secondary BAs in gastrointestinal cancers, the targeting of which may enhance therapeutic responses in their treatment.