Modeling human pancreatic ductal adenocarcinoma for translational research: current options, challenges, and prospective directions

Biological and Clinical Impacts of Glucose Metabolism in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer type as it is prone to metastases and is difficult to diagnose at an early stage. Despite advances in molecular detection, its clinical prognosis remains poor and it is expected to become the second leading cause of cancer-related deaths. Approximately 85% of patients develop glucose metabolism disorders, most commonly diabetes mellitus, within three years prior to their pancreatic cancer diagnosis. Diabetes, or glucose metabolism disorders related to PDAC, are typically associated with insulin resistance, and beta cell damage, among other factors. From the perspective of molecular regulatory mechanisms, glucose metabolism disorders are closely related to PDAC initiation and development and to late invasion and metastasis. In particular, abnormal glucose metabolism impacts the nutritional status and prognosis of patients with PDAC. Meanwhile, preliminary research has shown that metformin and statins are effective for the prevention or treatment of malignancies; however, no such effect has been shown in clinical trials. Hence, the causes underlying these conflicting results require further exploration. This review focuses on the clinical significance of glucose metabolism disorders in PDAC and the mechanisms behind this relationship, while also summarizing therapeutic approaches that target glycolysis.

Exploration of Patient-Derived Pancreatic Ductal Adenocarcinoma Ex Vivo Tissue for Treatment Response

Patient-derived tissue culture models are valuable tools to investigate drug effects and targeted treatment approaches. Resected tumor slices cultured ex vivo have recently gained interest in precision medicine, since they reflect the complex microenvironment of cancer tissue. In this study, we examined the treatment response to an internally developed ex vivo tissue culture model from pancreatic ductal adenocarcinoma (PDAC) and in vitro analysis. Seven PDAC tissues were cultured and subsequently treated with indole-3-pyruvic acid (IPA). IPA, which is known as an agonist of the aryl hydrocarbon receptor (AHR) pathway, has antioxidant properties. Genome-wide transcriptome sequencing analysis revealed activation of AHR pathway genes (CYP1A1 and CYP1B1, p ≤ 0.05). Additionally, significant upregulation of AHR repressor genes AHRR and TiPARP was also observed (p ≤ 0.05), which is indicative of the negative feedback loop activation of AHR pathway signaling. The overall transcriptomic response to IPA indicated that the tissues are biologically active and respond accordingly to exogenous treatment. Cell culture analysis confirmed the significant induction of selected AHR genes by IPA. A morphological examination of the paraffin-embedded formalin-fixed tissue did not show obvious signs of IPA treatment related to tumor cell damage. This study is a proof of concept that ex vivo patient-derived tissue models offer a valuable tool in precision medicine to monitor the effect of personalized treatments.

Covalent CES2 Inhibitors Protect against Reduced Formation of Intestinal Organoids by the Anticancer Drug Irinotecan

BACKGROUND

Irinotecan is widely used to treat various types of solid and metastatic cancer. It is an ester prodrug and its hydrolytic metabolite (SN-38) exerts potent anticancer activity. Irinotecan is hydrolyzed primarily by carboxylesterase-2 (CES2), a hydrolase abundantly present in the intestine such as the duodenum. We have identified several potent and covalent CES2 inhibi¬tors such as remdesivir and sofosbuvir. Remdesivir is the first small molecule drug approved for COVID-19, whereas sofosbuvir is a paradigm-shift medicine for hepatitis C viral infection. Irinotecan is generally well-tolerated but associated with severe/life-threatening diarrhea due to intestinal accu¬¬mula¬tion of SN-38.

OBJECTIVE

This study was to test the hypothesis that remdesivir and sofosbuvir protect against irinotecan-induced epithelial injury associated with gastrointestinal toxicity.

METHODS

To test this hypothesis, formation of organoids derived from mouse duodenal crypts, a robust cellular model for intestinal regeneration, was induced in the presence or absence of irinotecan +/- pretreatment with a CES2 drug inhibitor.

RESULTS

Irinotecan profoundly inhibited the formation of intestinal organoids and the magnitude of the inhibition was greater with female crypts than their male counterparts. Consistently, crypts from female mice had significantly higher hydrolytic activity toward irinotecan. Critically, remdesivir and sofosbuvir both reduced irinotecan hydrolysis and reversed irinotecan-reduced formation of organoids. Human duodenal samples robustly hydrolyzed irinotecan, stable CES2 transfection induced cytotoxicity and the cytotoxicity was reduced by CES2 drug inhibitor.

CONCLUSION

These findings establish a therapeutic rationale to reduce irinotecan-gastrointestinal injury and serve as a cellular foundation to develop oral formulations of irinotecan with high safety.

PDAC as an Immune Evasive Disease: Can 3D Model Systems Aid to Tackle This Clinical Problem?

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with a high mortality rate. The presence of a dense desmoplastic stroma rich in fibroblasts, extracellular matrix, and immune cells plays a critical role in disease progression, therapy response and is a distinguishing feature of PDAC. PDAC is currently treated with a combination of surgery, chemotherapy and radiation therapy in selected cases which results in long-term survival only in a small percentage of patients. Cancer therapies that incorporate immunotherapy-based techniques have become increasingly common in recent years. While such a strategy has been shown to be effective for immunogenic, “hot” tumors like melanoma and lung cancer, thus far PDAC patients display poor responses to this therapeutic approach. Various factors, such as low tumor mutational burden, increased infiltration of immunosuppressive cells, like MDSCs and Treg cells promote tolerance and immune deviation, further aggravating adaptive immunity in PDAC. In this review we will elaborate on the ability of PDAC tumors to evade immune detection. We will also discuss various 3D model system that can be used as a platform in preclinical research to investigate rational combinations of immunotherapy with chemotherapy or targeted therapy, to prime the immune microenvironment to enhance antitumor activity.