Cancer‐associated fibroblasts (CAFs) are key components of the dense, proliferating stroma observed in pancreatic ductal adenocarcinoma (PDAC), and CAF subpopulations drive tumor heterogeneity and play a major role in PDAC progression and drug resistance. CAFs consist of heterogenous subpopulations such as myoblastic CAF (myCAF) and inflammatory CAF (iCAF), and each has distinct essential roles. However, it is not clear how CAF subpopulations are formed in PDAC. Adipose‐derived MSCs (AD‐MSCs), which possess a high multilineage potential and self‐renewal capacity, are reported to be one of the in vivo CAF sources. Here, we aimed to investigate whether AD‐MSCs can act as precursors for CAFs in vitro. We recorded morphological features and collected omics data from two in vitro co‐culture models for recapitulating clinical PDAC. Additionally, we tested the advantages of the co‐culture model in terms of accurately modeling morphology and CAF heterogeneity. We showed that AD‐MSCs differentiate into two distinct CAF subpopulations: Direct contact co‐culture with PDAC cell line Capan‐1 induced differentiation into myCAFs and iCAFs, while indirect co‐culture induced differentiation into only iCAFs. Using these co‐culture systems, we also identified novel CAF markers that may be helpful for elucidating the mechanisms of CAFs in the tumor microenvironment (TME). In conclusion, AD‐MSCs can differentiate into distinct CAF subtypes depending on the different co‐culture conditions in vitro, and the identification of potential CAF markers may aid in future investigations of the mechanisms underlying the role of CAFs in the TME.

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For recurrent biliary tract cancer, chemotherapy is the standard treatment. However, the efficacy of surgery is unknown. Here, the prognostic benefit of surgery for recurrent biliary tract cancer was investigated. Data of 206 patients who underwent surgery for biliary tract cancer between 2005 and 2015 were retrospectively analyzed. Of these, 107 recurrent patients were divided into two groups, surgery (n = 14) and non-surgery (n = 93) groups. In the latter group, 45 patients received chemotherapy and 48 received best supportive care. Of the total 121 sites of recurrence, the liver was the most common (n = 41), followed by locoregional recurrence (n = 32) and lymph nodes (n = 18). Surgery was performed in the 14 patients with recurrence, comprising nine patients with intrahepatic cholangiocarcinoma, three with perihilar cholangiocarcinoma, one with distal cholangiocarcinoma and one with gallbladder carcinoma. Survival after recurrence was significantly better after surgery than after chemotherapy or best supportive care (38% vs. 5.3% vs. 0% at 3 years and 19% vs. 5.3% vs. 0% at 5 years; P < 0.0001). Multivariate analysis identified the residual status of the primary tumor (hazard ratio = 1.58, 95% confidence interval = 1.00-2.44; P = 0.047), time to recurrence ≥1 year (hazard ratio = 0.62, 95% confidence interval = 0.39-0.97; P = 0.037) and surgery for recurrence (hazard ratio = 0.32, 95% confidence interval = 0.14-0.62; P < 0.001) as independent prognostic factors. Surgery for recurrent biliary tract cancer may prolong survival in patients with time to recurrence ≥1 year.

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment perform glycolysis to produce energy, i.e., ATP. Since the origin of CAFs is unidentified, it is not determined whether the intracellular metabolism transitions from oxidative phosphorylation (OXPHOS) to glycolysis when normal tissue fibroblasts differentiate into CAFs. In this study, we established an experimental system and induced the in vitro differentiation of mesenchymal stem cells (MSCs) to CAFs. Additionally, we performed metabolomic and RNA-sequencing analyses before and after differentiation to investigate changes in the intracellular metabolism. Consequently, we discovered that OXPHOS, which was the primary intracellular metabolism in MSCs, was reprogrammed to glycolysis. Furthermore, we analyzed the metabolites in pancreatic tumor tissues in a mice model. The metabolites extracted as candidates in the in vitro experiments were also detected in the in vivo experiments. Thus, we conclude that normal tissue fibroblasts that differentiate into CAFs undergo a metabolic reprogramming from OXPHOS to glycolysis. Moreover, we identified the CAF-specific metabolites expressed during metabolic reprogramming as potential future biomarkers for pancreatic cancer.

Isorhamnetin (ISO), a dietary flavonoid, has been shown to possess antioxidant, anti-cancer, and anti-inflammatory properties. Cancer-associated fibroblasts (CAFs), found in the tumor microenvironment of several types of cancer including pancreatic ductal adenocarcinoma (PDAC) impact the tumor growth and development of chemoresistance. Thus, modulating CAFs is an attractive mean to increase the efficacy of therapies targeting cancer cells. In this study, the anti-proliferative effect of ISO and the underlying transcriptomic profile of ISO-treated PDAC-derived CAFs were investigated. ISO treatment showed a time- and concentration-dependent decrease in cell viability with a slight increase in apoptotic cells. Microarray and cell cycle analyses revealed ISO induced downregulation of pathways in cell cycle and DNA replication; and G2/M checkpoint. Cell cycle analysis showed cells in the G2/M phase were increased. In response to the treatment, hallmark for p53 pathway genes, known to regulate cell cycle checkpoints, were highly upregulated. Moreover, ISO-treated cells had an increased area of the mitochondrial network, but lower mitochondrial membrane potential accompanied by a decrease of ATP production, measured by oxygen consumption rate. Inflammatory gene expression of IL1A1, IL6, CXCL1, and LIF were significantly inhibited in ISO-treated CAFs. Taken together, our results demonstrated that the cytostatic effect of ISO on human CAFs was mediated by inducing cell cycle arrest at G2/M phase associated with activation of p21, impaired mitochondrial homeostasis, and inhibition of inflammatory mediators gene expression, warranting further investigation for its use in combinatorial therapy that target both the cancer and the tumor microenvironment as a whole.

Present treatment strategy for unresectable locally advanced (UR-LA) pancreatic ductal adenocarcinoma (PDAC) patients is controversial. Hence, a triple-modal therapy, which is a multidisciplinary strategy, was designed for patients with UR-LA PDAC by adding hyperthermia to conventional chemoradiotherapy at our institution. In this study we aimed to evaluate the effectiveness of this strategy. Data of 21 UR-LA PDAC patients who underwent the triple-modal treatment were retrospectively analyzed for evaluating the safety and oncological effect of the treatment. The treatment schedule included, five concurrent infusions of gemcitabine (800 mg/m2) followed by hyperthermia (1 h) and X-ray (2 Gy) or proton beam radiation (2.7 Gy) on days 1, 8, 15, 29, and 36. Additional radiotherapies applied a total dose of 50 Gy/25 fr for X-ray radiation or 67.5 Gy/25 fr for proton beam radiation. Median overall survival (OS) was 23.6 months. Conversion surgery was performed in 5 patients (23.8%), and a R0 margin could be achieved in 4 of them; however, their median OS (16.3 months) tended to be shorter than that of the patients who did not undergo resection (23.6 months, p = 0.562). Further, the median OS of patients who underwent proton beam radiation (28.0 months) was significantly longer than that of patients who underwent X-ray radiation (13.9 months, p = 0.045). Most adverse events were manageable, except for one grade 3 gastric ulcer. The median tumor size and marker reduction rates were -17% and -91%, respectively. The tumor responses were partial response, stable disease, and progressive disease in 3, 15, and 3 patients, respectively. Triple-modal strategy, especially when combined with proton beam radiation, is feasible and results in favorable survival outcomes in patients with UR-LA PDAC.