Search

Cancer cells craftily adapt their energy metabolism to their microenvironment. Nutrient deprivation due to hypovascularity and fibrosis is a major characteristic of pancreatic ductal adenocarcinoma (PDAC); thus, PDAC cells must produce energy intrinsically. However, the enhancement of energy production via activating Kras mutations is insufficient to explain the metabolic rewiring of PDAC cells. Here, we investigated the molecular mechanism underlying the metabolic shift in PDAC cells under serine starvation. Amino acid analysis revealed that the concentrations of all essential amino acids and most nonessential amino acids were decreased in the blood of PDAC patients. In addition, the plasma serine concentration was significantly higher in PDAC patients with PHGDH-high tumors than in those with PHGDH-low tumors. Although the growth and tumorigenesis of PK-59 cells with PHGDH promoter hypermethylation were significantly decreased by serine starvation, these activities were maintained in PDAC cell lines with PHGDH promoter hypomethylation by serine biosynthesis through PHGDH induction. In fact, DNA methylation analysis by pyrosequencing revealed that the methylation status of the PHGDH promoter was inversely correlated with the PHGDH expression level in human PDAC tissues. In addition to PHGDH induction by serine starvation, PDAC cells showed enhanced serine biosynthesis under serine starvation through 3-PG accumulation via PGAM1 knockdown, resulting in enhanced PDAC cell growth and tumor growth. However, PHGDH knockdown efficiently suppressed PDAC cell growth and tumor growth under serine starvation. These findings provide evidence that targeting the serine biosynthesis pathway by inhibiting PHGDH is a potent therapeutic approach to eliminate PDAC cells in nutrient-deprived microenvironments. [ABSTRACT FROM AUTHOR]

Fibroblast activation protein (FAP) generally shows low or undetectable expression in most normal tissues but is highly expressed in fibroblasts in almost all carcinomas. FAP is one of the potential molecules to detect activated fibroblasts and has multiple roles in tumour progression. We generated transgenic mice that specifically expressed tdTomato along with FAP promoter activity. Coculturing a mouse gastric cancer cell line and FAP‐tdTomato transgenic mouse‐derived fibroblasts showed that tdTomato expression was elevated in the cocultured fibroblasts. Moreover, stomach wall transplanted tumours in mice also showed FAP‐tdTomato expression in fibroblasts of the stomach and each metastatic legion. These results indicated that FAP‐tdTomato expression in fibroblasts was elevated by stimulation through the interaction with cancer cells. Functionally, collagen production was increased in FAP/tdTomato‐positive fibroblasts cocultured with mouse cancer cells. These FAP‐tdTomato transgenic mice have the potential to be used to investigate real‐time FAP dynamics and the importance of FAP expression in tumour development. [ABSTRACT FROM AUTHOR]

Background: Remodeling the tumor microenvironment (TME) to benefit cancer cells is crucial for tumor progression. Although diffuse-type gastric cancer (DGC) preferentially interacts with the TME, the precise mechanism of the complicated network remains unknown. This study aimed to investigate the mutual activation mechanism underlying DGC progression. Methods: Mass cytometry analysis of co-cultured macrophages, noncancerous fibroblasts (NFs), and DGC cells was performed. RNA sequencing was applied to examine gene expression in fibroblasts. DGC cells were treated with cytokines to examine their effect on characteristic changes. The TCGA and Kumamoto University cohorts were used to evaluate the clinical relevance of the in vitro findings. Results: Cohort analysis revealed that DGC patients had a poor prognosis. The fibroblasts and macrophages interacted with DGC cells to form a cell cluster in the invasive front of DGC tissue. The original 3D triple co-culture system determined the promotional effects of nonmalignant cells on DGC invasive growth. We notably identified a mixed-polarized macrophage cell type with M1/M2 cell surface markers in a triple co-culture system. IL-1β from mixed-polarized macrophages induced the conversion of NFs to cancer-associated fibroblast-like (CAF-like) cells, promoting the malignant phenotype of DGC cells by inducing the secretion of IL-6, IL-24, and leukemia inhibitory factor (LIF). Moreover, IL-6 and colony stimulating factor 2 (GM-CSF) cooperated to maintain the stable state of mixed-polarized macrophages. Finally, we found that mixed-polarized macrophages were frequently detected in DGC tissues. Conclusion: These findings demonstrated that mixed-polarized macrophages exist as a novel subtype through the reciprocal interaction between DGC cells and nonmalignant cells. [ABSTRACT FROM AUTHOR]

Background: Signet ring cell carcinoma (SRCC) is a particular histologic variant of gastric cancer (GC). However, the critical factor related to the aggressive characteristics of SRCC has not been determined. Methods: We collected surgically resected tissues from 360 GC patients in the Kumamoto University cohort and generated survival curves via the Kaplan–Meier method. In vitro, we identified the specific transcript variant of MUC20 in SRCC cells by direct sequencing and investigated the role of MUC20 in GC progression using GC cells with MUC20 silencing and forced expression. In vivo, we examined chemoresistance using MUC20 variant 2 (MUC20v2)-overexpressing non-SRCC cells to construct a xenograft mouse model. Results: We analyzed a comprehensive GC cell line database to identify the specifically expressed genes in gastric SRCC. We focused on MUC20 and investigated its role in GC progression. Survival analysis revealed that GC patients with high MUC20 expression exhibited a poor prognosis and that MUC20 expression was significantly correlated with SRCC histological type. Moreover, we found that gastric SRCC cells specifically expressed MUC20v2, which was dominantly expressed in the cytoplasm. Silencing MUC20v2 caused cell death with characteristic morphological changes in gastric SRCC cells. To further determine the types of cell death, we examined apoptosis, pyroptosis and ferroptosis by detecting cleaved PARP, gasdermin E-N-terminal (GSDME-N), and lipid reactive oxygen species (ROS) levels, respectively. We found that apoptosis and pyroptosis occurred in MUC20-silenced gastric SRCC cells. In addition, MUC20v2-overexpressing GC cells exhibited chemoresistance to cisplatin (CDDP) and paclitaxel (PTX). RNA sequencing revealed that the pathways involved in intracellular calcium regulation were significantly upregulated in MUC20v2-overexpressing GC cells. Notably, forced expression of MUC20v2 in the cytoplasm of GC cells led to the maintenance of mitochondrial calcium homeostasis and mitochondrial membrane potential (MMP), which promoted cell survival and chemoresistance by suppressing apoptosis and pyroptosis. Finally, we investigated the significance of MUC20v2 in a xenograft model treated with CDDP and showed that MUC20v2 overexpression caused chemoresistance by inhibiting cell death. Conclusion: These findings highlight the novel functions of MUC20v2, which may confer cell survival and drug resistance in GC cells. Significance: MUC20v2 protects GC cells from apoptosis and pyroptosis by maintaining mitochondrial calcium levels and mitochondrial membrane potential and subsequently induces drug resistance. [ABSTRACT FROM AUTHOR]

Background: With population aging, the number of frail patients with pancreatic cancer has increased. The Clinical Frailty Scale (CFS) is a simple and validated tool to assess frailty, and higher scores predict worse clinical outcomes after cardiovascular surgery. In this retrospective study, we aimed to examine the association of preoperative frailty with prognosis after resection for pancreatic cancer. Methods: We retrospectively analyzed data from 142 consecutive patients undergoing resection for pancreatic cancer between April 2010 and December 2018. We used the CFS: 1 (very fit) to 9 (terminally ill) to assess frailty and examined associations of the CFS scores with recurrence-free survival (RFS), cancer-specific survival (CSS), and overall survival (OS). Multivariable Cox proportional hazards models were used to calculate hazard ratios (HRs), controlling for potential confounders. Results: Of the 142 patients, 113 (80%) had CFS scores of ≤ 3, 13 (9.2%) scores of 4, and 16 (11%) scores of ≥ 5. Scores of ≥ 5 on the CFS were associated with worse CSS (univariable HR: 2.62, 95% confidence interval [CI]: 1.19–5.18, P = 0.019; multivariable HR: 2.49, 95% CI 1.05–5.34, P = 0.039) and OS (univariable HR: 2.42, 95% CI 1.19–4.46, P = 0.016; multivariable HR: 2.25, 95% CI 1.05–4.43, P = 0.038). The association between CFS scores and RFS was not significant in multivariable analysis (univariable HR: 2.11, 95% CI 1.08–3.79, P = 0.030; multivariable HR: 1.47, 95% CI 0.71–2.83, P = 0.29). Conclusion: Higher scores on the CFS are associated with worse CSS and OS after resection for pancreatic cancer. Preoperative measurement of frailty may improve risk assessment among patients with pancreatic cancer. [ABSTRACT FROM AUTHOR]

Background: Whether perioperative allogeneic blood transfusion (PABT) negatively influences patient survival after hepatectomy (HR) for hepatocellular carcinoma (HCC) remains controversial. Methods: Five hundred two patients who underwent HR for initial HCC between 1994 and 2015 were enrolled in this study. All patients were divided into two groups: the PABT group and the non-PABT group. Differences of clinicopathological factors, overall survival (OS), recurrence-free survival (RFS), and the recurrence pattern between the two groups were evaluated. Using propensity score matching for tumor-related factors, liver functions, and surgical factors (total 11 factors), the survival impact of PABT was also analyzed. Results: In the entire cohort, 78 patients (15.5%) received PABT such as red cell concentrate, fresh-frozen plasma, or platelets. OS (5-year OS: 55% vs. 76%; p = 0.0005) and RFS (2-year RFS: 47% vs. 56%; p = 0.0131) were significantly worse in the PABT group. The extrahepatic recurrence happened more frequently in the PABT group (15% vs. 5.4%; p = 0.0039). There were many significant clinicopathological differences between the two groups: more advanced tumor stage (tumor diameter, stage III or IV, microvascular invasion), worse liver functions (albumin, indocyanine green retention rate at 15 min), and more surgical stress (blood loss, operation time) in the PABT group. After propensity score matching, 43 pairs of patients were extracted. In this matched cohort, the survival curves of the PABT and non-PABT groups almost completely overlapped both in OS (5-year OS: 62% vs. 62%; p = 0.4384) and in RFS (2-year RFS: 49% vs. 47%; p = 0.8195). The significant difference of the extrahepatic recurrence rate disappeared in the matched cohort (p = 0.5789). Conclusion: Using propensity score matching, we found that PABT does not influence patient survival after HR for HCC. [ABSTRACT FROM AUTHOR]