Removal of gemcitabine-induced senescent cancer cells by targeting glutaminase1 improves the therapeutic effect in pancreatic ductal adenocarcinoma.

Insufficient cancer treatment can induce senescent cancer cell formation and treatment resistance. The characteristics of induced senescent cancer (iSnCa) cells remain unclear. Pancreatic ductal adenocarcinoma (PDAC) has a low and nondurable response rate to current treatments. Our study aimed to analyze the properties of iSnCa cells and the relationship between cellular senescence and prognosis in PDAC. We evaluated the characteristics of gemcitabine-induced senescent cancer cells and the effect of senescence-associated secretory phenotype (SASP) factors released by iSnCa cells on surrounding PDAC cells. The relationship between cellular senescence and the prognosis was investigated in 50 patients with PDAC treated with gemcitabine-based neoadjuvant chemotherapy. Exposure to 5 ng/mL gemcitabine-induced senescence, decreased proliferation and increased senescence-associated ß-galactosidase-cell staining without cell death in PDAC cells; the expression of glutaminase1 (GLS1) and SASP factors also increased and caused epithelial-mesenchymal transition in surrounding PDAC cells. iSnCa cells were selectively removed by the GLS1 inhibitor bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl sulfide (BPTES) through apoptosis induction. Cellular senescence was induced in PDAC cells via insufficient gemcitabine in subcutaneous tumor model mice. GLS1 expression was an independent prognostic factor in patients with PDAC who received gemcitabine-based neoadjuvant chemotherapy. This is the first study to identify the relationship between senescence and GLS1 in PDAC. Low-dose gemcitabine-induced senescence and increased GLS1 expression were observed in PDAC cells. Cellular senescence may contribute to treatment resistance of PDAC, hence targeting GLS1 in iSnCa cells may improve the therapeutic effect.

KLK10 derived from tumor endothelial cells accelerates colon cancer cell proliferation and hematogenous liver metastasis formation.

Tumor endothelial cells (TECs), which are thought to be structurally and functionally different from normal endothelial cells (NECs), are increasingly attracting attention as a therapeutic target in hypervascular malignancies. Although colorectal liver metastasis (CRLM) tumors are hypovascular, inhibitors of angiogenesis are a key drug in multidisciplinary therapy, and TECs might be involved in the development and progression of cancer. Here, we analyzed the function of TEC in the CRLM tumor microenvironment. We used a murine colon cancer cell line (CT26) and isolated TECs from CRLM tumors. TECs showed higher proliferation and migration than NECs. Coinjection of CT26 and TECs yielded rapid tumor formation in vivo. Immunofluorescence analysis showed that coinjection of CT26 and TECs increased vessel formation and Ki-67+ cells. Transcriptome analysis identified kallikrein-related peptide 10 (KLK10) as a candidate target. Coinjection of CT26 and TECs after KLK10 downregulation with siRNA suppressed tumor formation in vivo. TEC secretion of KLK10 decreased after KLK10 downregulation, and conditioned medium after KLK10 knockdown in TECs suppressed CT26 proliferative activity. Double immunofluorescence staining of KLK10 and CD31 in CRLM tissues revealed a significant correlation between poor prognosis and positive KLK10 expression in TECs and tumor cells. On multivariate analysis, KLK10 expression was an independent prognostic factor in disease-free survival. In conclusion, KLK10 derived from TECs accelerates colon cancer cell proliferation and hematogenous liver metastasis formation. KLK10 in TECs might offer a promising therapeutic target in CRLM.

Skeletal Muscle-Derived Irisin Enhances Gemcitabine Sensitivity and Suppresses Migration Ability in Pancreatic Ductal Adenocarcinoma.

BACKGROUND: High skeletal muscle mass might be a prognostic factor for patients with pancreatic ductal adenocarcinoma (PDAC); however, the underlying reason is unclear. We hypothesized that myokines, which are cytokines secreted by the skeletal muscle, function as suppressors of PDAC. We specifically examined irisin, a myokine, which plays a critical role in the modulation of metabolism, to clarify the anticancer mechanisms. METHODS: First, the effect of the conditioned medium (CM) from skeletal muscle cells and from irisin-knockdown skeletal muscle cells on PDAC cell lines was evaluated. We then investigated the effects and anticancer mechanism of irisin in PDAC cells, and evaluated the anticancer effect of recombinant irisin in a PDAC xenograft mouse model. Finally, patients undergoing pancreatic resection for PDAC were divided into two groups based on their serum irisin level, and the long-term outcomes were evaluated. RESULTS: The CM enhanced gemcitabine sensitivity by inducing apoptosis and decreasing cell migration by inhibiting epithelial-mesenchymal transition (EMT) in PDAC cell lines. The CM derived from irisin-knockdown skeletal muscle cells did not affect the PDAC cell lines. The addition of recombinant irisin to PDAC cell lines facilitated sensitivity to gemcitabine by inhibiting the mitogen-activated protein kinase (MAPK) pathway, and decreased migration by inhibiting EMT via the transforming growth factor-ß/SMAD pathway. Xenografts injected with gemcitabine and recombinant irisin grew slower than the xenografts injected with gemcitabine alone. The overall survival was prolonged in the high-irisin group compared with that in the low-irisin group. CONCLUSIONS: Skeletal muscle-derived irisin may affect PDAC by enhancing its sensitivity to gemcitabine and suppressing EMT.

Results of a Randomized Clinical Study of Gemcitabine Plus Nab-Paclitaxel Versus Gemcitabine Plus S-1 as Neoadjuvant Chemotherapy for Resectable and Borderline Resectable Pancreatic Ductal Adenocarcinoma (RCT, CSGO-HBP-015).

BACKGROUND: The optimal neoadjuvant chemotherapy (NAC) regimen for patients with localized pancreatic ductal adenocarcinoma (PDAC) remains uncertain. This trial aimed to evaluate the efficacy and safety of two neoadjuvant chemotherapy (NAC) regimens, gemcitabine plus nab-paclitaxel (GA) and gemcitabine plus S-1 (GS), in patients with resectable/borderline-resectable (R/BR) PDAC. PATIENTS AND METHODS: Treatment-naïve patients with R/BR-PDAC were enrolled and randomly allocated. They received two cycles (2 months) of each standard protocol, followed by radical surgery for those without tumor progression in general hospitals belonging to our intergroup. The primary endpoint was to determine the superior regimen on the basis of achieving a 10% increase in the rate of patients with progression-free survival (PFS) at 2 years from allocation. RESULTS: A total of 100 patients were enrolled, with 94 patients randomly assigned to the GS arm (N = 46) or GA arm (N = 48). The 2-year PFS rates did not show the stipulated difference [GA, 31% (24-38%)/GS, 26% (18-33%)], but the Kaplan-Myer analysis showed significance (median PFS, GA/GS 14 months/9 months, P = 0.048; HR 0.71). Secondary endpoint comparisons yielded the following results (GA/GS arm, P-value): rates of severe adverse events during NAC, 73%/78%, P = 0.55; completion rates of the stipulated NAC, 92%/83%, P = 0.71; resection rates, 85%/72%, P = 0.10; average tumor marker (CA19-9) reduction rates, -50%/-21%, P = 0.01; average numbers of lymph node metastasis, 1.7/3.2, P = 0.04; and median overall survival times, 42/22 months, P = 0.26. CONCLUSIONS: This study found that GA and GS are viable neoadjuvant treatment regimens in R/BR-PDAC. Although the GA group exhibited a favorable PFS outcome, the primary endpoint was not achieved.

ASO Author Reflections: Potential of Peripheral Plasma Exosomal miRNA: miR-6855-5p Could Predict Radiosensitivity in Patients with Pancreatic Cancer, and Enhances Radioresistance.

The efficacy of preoperative treatment for pancreatic cancer (PC) has been reported in randomized controlled trials, but the optimal regimen and the appropriateness of combining radiotherapy remain controversial. Therefore, predicting the efficacy of preoperative treatment using biomarkers and determining whether to combine chemotherapy or radiotherapy based on the biology of individual tumors could help personalize treatment and maximize therapeutic outcomes. In this study, a microRNA (miRNA) microarray analysis was performed using peripheral blood plasma exosomes from 10 PC patients who underwent neoadjuvant chemoradiotherapy, leading to the identification of miR-6855-5p as a candidate miRNA. miR-6855-5p was found to induce radioresistance in PC cells. In another cohort of 28 patients, it was observed that those with higher expression levels of miR-6855-5p in peripheral blood plasma exosomes tended to have increased radioresistance (r = - 0.5964). In future, measuring plasma exosomal miR-6855-5p before treatment could potentially lead to precision medicine by personalizing the decision of whether to include radiotherapy in the treatment plan.

miR-6855-5p Enhances Radioresistance and Promotes Migration of Pancreatic Cancer by Inducing Epithelial-Mesenchymal Transition via Suppressing FOXA1: Potential of Plasma Exosomal miR-6855-5p as an Indicator of Radiosensitivity in Patients with Pancreatic Cancer.

BACKGROUND: Whether radiation should be added to neoadjuvant treatment remains controversial, and liquid biopsy has not been reported to predict radioresistance in pancreatic cancer (PC). We aimed to identify microRNAs (miRNAs) governing radioresistance in PC by utilizing peripheral plasma exosome samples and to verify their usefulness as biomarkers. METHODS: miRNA microarray analysis was conducted using pretreatment peripheral plasma exosomes from 10 patients with PC receiving neoadjuvant chemoradiotherapy (NACRT) in the discovery cohort. Patients were categorized into two groups (good and poor responders) based on treatment responses, and candidate miRNAs exhibiting differential expression between the two groups were identified. The radiosensitivity of PC cells was examined after miR-6855-5p overexpression. Next-generation sequencing (NGS) and TargetScan were used to explore the mechanisms of radioresistance. We investigated the correlation between miR-6855-5p expression levels in the pretreatment peripheral plasma exosomes of 28 patients in the validation cohort and the response to NACRT. RESULTS: miR-6855-5p expression was higher in poor responders than in good responders. miR-6855-5p induces radioresistance in PC cells. NGS showed that epithelial-mesenchymal transition (EMT) was involved in miR-6855-5p-related radioresistance. Forkhead box protein A1 (FOXA1) was identified as a direct target of miR-6855-5p using NGS and TargetScan. Clinical examination of samples from the validation cohort revealed a tendency for patients with higher expression of miR-6855-5p in peripheral plasma exosomes to exhibit increased radioresistance (r = -0.5964). CONCLUSIONS: miR-6855-5p regulates the radioresistance of PC by inducing EMT via suppressing FOXA1, and miR-6855-5p in peripheral plasma exosomes may be a biomarker for radioresistance of PC.

Prognostic Significance of Biologic Factors in Patients with a Modest Radiologic Response to Neoadjuvant Treatment for Resectable and Borderline Resectable Pancreatic Cancers: Impact of the Combination Index of Sialyl-Lewis Antigen-Related Tumor Markers.

BACKGROUND: Appropriate re-evaluation after neoadjuvant treatment (NAT) is important for optimal treatment selection. Nonetheless, determining the operative eligibility of patients with a modest radiologic response remains controversial. This study aimed to assess the prognostic significance of biologic factors for patients showing a modest radiologic response to NAT and investigate the tumor markers (TMs), CA19-9 alone, DUPAN-II alone, and their combination, to create an index that combines these sialyl-Lewis antigen-related TMs associated with treatment outcomes. METHODS: This study enrolled patients deemed to have a "stable disease" by RECIST classification with slight progression (tumor size increase rate, ≤20%) as their radiologic response after NAT. A sialyl-Lewis-related index (sLe index), calculated by adding one fourth of the serum DUPAN-II value to the CA19-9 value, was created. The prognostic significances of CA19-9, DUPAN-II, and the sLe index were assessed in relation to postoperative outcomes. RESULTS: An sLe index lower than the cutoff value (45.25) was significantly associated with favorable disease-free survival. Moreover, the post-NAT sLe index had a higher area under the curve value for recurrence within 24 months than the post-NAT levels of CA19-9 or DUPAN-II alone. Multivariable analysis showed that a post-NAT sLe index higher than 45.25 was the single independent predictive factor for recurrence within 24 months. CONCLUSIONS: Additional evaluation of biologic factors can potentially enhance patient selection, particularly for patients showing a limited radiologic response to NAT. The authors' index is a simple indicator for the biologic evaluation of multiple combined sialyl-Lewis antigen-related TMs and may offer a better predictive significance.

Preoperative treatment response prediction for pancreatic cancer by multiple microRNAs in plasma exosomes: Optimization using machine learning and network analysis.

BACKGROUND/OBJECTIVES: MicroRNAs (miRNAs) are involved in chemosensitivity through their biological activities in various malignancies, including pancreatic cancer (PC). However, single-miRNA models offer limited predictability of treatment response. We investigated whether a multiple-miRNA prediction model optimized via machine learning could improve treatment response prediction. METHODS: A total of 20 and 66 patients who underwent curative resection for PC after gemcitabine-based preoperative treatment were included in the discovery and validation cohorts, respectively. Patients were classified according to their response to preoperative treatment. In the discovery cohort, miRNA microarray and machine learning were used to identify candidate miRNAs (in peripheral plasma exosomes obtained before treatment) associated with treatment response. In the validation cohort, miRNA expression was analyzed using quantitative reverse transcription polymerase chain reaction to validate its ability to predict treatment response. RESULTS: In the discovery cohort, six and three miRNAs were associated with good and poor responders, respectively. The combination of these miRNAs significantly improved predictive accuracy compared with using each single miRNA, with area under the curve (AUC) values increasing from 0.485 to 0.672 to 0.909 for good responders and from 0.475 to 0.606 to 0.788 for poor responders. In the validation cohort, improved predictive performance of the miRNA combination over single-miRNA prediction models was confirmed, with AUC values increasing from 0.461 to 0.669 to 0.777 for good responders and from 0.501 to 0.556 to 0.685 for poor responders. CONCLUSIONS: Peripheral blood miRNA profiles using an optimized combination of miRNAs may provide a more advanced prediction model for preoperative treatment response in PC.

Prognostic impact of aberrant right hepatic artery involvement in patients with pancreatic cancer: A multicenter retrospective cohort study.

BACKGROUND AND OBJECTIVES: This study aimed to evaluate the prognostic value of aberrant right hepatic artery (A-RHA) involvement in patients with pancreatic cancer (PC). METHODS: This study enrolled 474 patients who underwent upfront pancreatectomy or neoadjuvant treatment for resectable (R) or borderline resectable (BR) PC from four institutions. The patients were divided into three groups: A-RHA involvement group (n = 12), patients who had sole A-RHA involvement without major arterial involvement; BR-A group (n = 104), patients who had major arterial involvement; R/BR-PV group (n = 358), others. RESULTS: All patients in the A-RHA involvement group underwent margin-negative resection. The median overall survival of the entire cohort in the A-RHA involvement, R/BR-PV, and BR-A groups was 41.2, 33.5, and 25.2 months, respectively. Although survival in the R/BR-PV group was significantly more favorable than that in the BR-A group (p = 0.0003), no significant difference was observed between the A-RHA involvement group and the R/BR-PV (p = 0.7332) and BR-A (p = 0.1485) groups. CONCLUSIONS: The prognosis of patients with PC and sole A-RHA involvement was comparable to that of patients with R/BR-PV.

Apparent diffusion coefficient in intrahepatic cholangiocarcinoma diffusion-weighted magnetic resonance imaging noninvasively predicts Ki-67 expression.

AIM: Tumor Ki-67 expression reflects prognosis and cancer grade, and biopsy-based preoperative assessment of Ki-67 expression is key to treatment. Apparent diffusion coefficient (ADC) values obtained with this imaging may noninvasively predict Ki-67 by reflecting tumor cell density and limited water molecule movement from irregular alignment. This study aimed to investigate the ability of ADC values to predict Ki-67 expression in intrahepatic cholangiocarcinoma (ICC). METHOD: We retrospectively analyzed 39 cases of ICC confirmed by surgical pathology. All patients had undergone magnetic resonance imaging, and ADC values (mean, minimum, and maximum) were calculated. Ki-67 expression was assessed by immunohistochemistry, and patients were divided into groups of high (n = 18) and low (n = 21) Ki-67 expression. To assess the diagnostic performance of the ADC values for Ki-67 expression, we used the receiver operating characteristic curve and compared the areas under the curve (AUC). RESULTS: The mean and minimum ADC values were significantly lower in the group with high Ki-67 expression. For predicting high Ki-67 expression, the AUC values were 0.701 for mean ADC, 0.818 for minimum ADC, and 0.571 for maximum ADC. The diagnostic sensitivity and specificity of the minimum ADC values were 88.9% and 76.2%, respectively. In addition, with ADC values combined, the AUC increased to 0.831. Apparent diffusion coefficient is a useful predictor of Ki-67 expression level in ICC. CONCLUSION: Apparent diffusion coefficient values, especially minimum ADC values, can noninvasively predict ICC associated with high Ki-67 expression.

Application of a laparoscopic device for cell-derived sheet transplantation on the liver in a porcine model.

BACKGROUND: Cell-derived sheets are of global interest for regenerative therapy. Transplanting a sheet for abdominal organs requires a device for laparoscopic delivery to minimize invasiveness. Here, using a porcine model, we aimed to confirm the feasibility of a device developed to deliver sheets to the thoracic cavity in a laparoscopic transplantation procedure. MATERIAL AND METHODS: We used the device to transplant human skeletal myoblast cell sheets onto the liver and measured extra-corporeal, intra-abdominal, and total procedure times for sheet transplantation. Tissues, including the liver and the sheet, were collected two days after transplantation and analyzed histologically. RESULTS: In all experiments (n = 27), all sheets were successfully placed at target locations. The mean (± standard deviation) extra-corporeal, intra-abdominal, and total procedure times were 44 ± 29, 33 ± 12, and 77 ± 36 s, respectively. We found no difference between the two surgeons in procedure times. Histological analyses showed no liver damage with the transplantation and that sheets were transplanted closely onto the liver tissue without gaps. CONCLUSION: We confirmed the feasibility of a simple universal device to transplant cell-derived sheets via laparoscopic surgery. This device could support a minimally invasive procedure for sheet transplantation.

Prognostic Impact of Gastroduodenal Artery Involvement in Cancer of the Pancreatic Head.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) contacting major arteries such as the celiac, common hepatic, and superior mesenteric artery is linked to poor prognosis and classified as borderline resectable. Although PDAC involving the gastroduodenal artery (GDA) is considered resectable, the prognostic impact of GDA involvement remains unclear. Here we investigated the prognostic impact of GDA involvement in PDAC after resection. METHODS: This study included 105 patients with resectable PDAC or borderline resectable with portal vein involvement. Patients were divided into two groups: those with tumor-GDA contact ≤ 180° and those with GDA contact > 180°. We evaluated the prognostic impact of GDA involvement between these groups. RESULTS: Both recurrence-free and overall survival after the surgery were significantly poorer with GDA contact > 180° than ≤ 180°. The poorer prognosis with GDA contact > 180° was verified by multivariate analysis and propensity score matching analysis to match patient backgrounds between the groups. The frequency of postoperative distant metastasis was also significantly higher in patients with GDA contact > 180°. CONCLUSIONS: GDA involvement is an independent factor significantly associated with postoperative survival in PDAC, and the poorer prognosis with GDA involvement may be linked to the development of postoperative distant metastasis.

Automated Analysis for the Prevalence of Cancer-Associated Fibroblasts in Resected Specimens of Intrahepatic Cholangiocarcinoma is a Simple and Reliable Evaluation System.

BACKGROUND: Intrahepatic cholangiocarcinoma (iCCA) has a high recurrence rate and poor prognosis, and chemotherapy options are limited. The prevalence of cancer-associated fibroblasts (CAFs) in iCCA has recently emerged as a prognostic marker and therapeutic target. A method to quantify the expression of CAFs is needed; however, a simple and reliable quantification method has not yet been established. OBJECTIVE: The aim of this study was to establish a simple and reliable method of quantifying CAFs. METHODS: A total of 71 patients with iCCA who underwent curative resection from November 2006 to October 2020 in our hospital were investigated. Immunohistochemistry for alpha-smooth muscle actin (α-SMA) was performed and α-SMA-positive cells were quantified by an automated analysis system (new method) and visually counted (conventional method). The times required for measurement and the prognosis were compared. RESULTS: The results of the quantification of CAFs by the new method were significantly correlated with the results by the conventional method, and the time required for measurement was significantly shorter with the new method. Patients with high-intensity CAFs showed a significantly poorer prognosis in terms of overall survival (OS) and the cumulative hepatic recurrence rate. In addition, high α-SMA levels were a significant risk factor for OS in multivariate analysis. CONCLUSIONS: This new method may contribute to the management of patients with iCCA, not only for the prediction of prognosis of patients with iCCA, but also for the indication of targeted therapy against CAFs.

Change Impact of Body Composition During Neoadjuvant Chemoradiotherapy in Patients with Resectable and Borderline Resectable Pancreatic Ductal Adenocarcinoma Undergoing Pancreatectomy.

BACKGROUND: The change impact of body composition during neoadjuvant therapy on clinical outcomes in patients with pancreatic ductal adenocarcinoma (PDAC) remains unclear. The aim of this study was to investigate the association between changes in body composition during neoadjuvant chemoradiotherapy (NACRT) and postoperative outcomes in patients with PDAC undergoing pancreatectomy, using three-dimensional images. METHODS: We reviewed 66 consecutive patients with resectable/borderline resectable PDAC receiving gemcitabine and S-1 with radiotherapy between April 2010 and June 2016. Body compositions were evaluated pre- and post-NACRT. All patients were hospitalized and supplied with regulated diet during NACRT treatment. RESULTS: Psoas major muscle volume index (PMI), abdominal fat volume index, and visceral fat volume index decreased significantly after NACRT (P < 0.0001, P < 0.0001, P < 0.0001, respectively). The post-NACRT CA19-9 level decreased significantly in the small-PMI-decrease group compared with the large-PMI-decrease group (P = 0.046). Recurrence-free survival (RFS) and overall survival (OS) of the large-PMI-decrease group were significantly poorer than those of the small-PMI-decrease group (P = 0.002, P = 0.006, respectively). On the other hand, there were no significant differences in RFS and OS between groups with high and low PMI, at the point of either pre-NACRT (P = 0.117, P = 0.123, respectively) or post-NACRT (P = 0.065, P = 0.064, respectively). Multivariate analysis identified a large percentage decrease in PMI as an independent risk factor for recurrence and death (P = 0.003, P = 0.002, respectively). CONCLUSIONS: Loss of skeletal muscle mass during NACRT was an independent risk factor for survival in patients with PDAC.

Investigation of the variation of vessels around the pancreatic head based on the first jejunal vein anatomy at pancreaticoduodenectomy.

PURPOSE: Pancreaticoduodenectomy (PD) for pancreatic cancer carries a high risk of massive intraoperative blood loss. The artery first approach (AFA) prevents blood loss during PD, but the optimal approach is unclear. The first jejunal vein (FJV) often comprises multiple veins and broadly supports venous drainage of the proximal jejunum. Its ligation carries a risk of proximal jejunum congestion. Here we investigated the anatomical characteristics of PD-associated vessels and AFA approach selection based on FJV anatomy. METHODS: This study included 148 Japanese living donors for liver transplantation. We reviewed their computed tomography images and assessed the anatomical pattern of PD-associated vessels in terms of FJV anatomy. RESULTS: The FJV traveled posterior to the superior mesenteric artery in 128 patients (86.5%, dorsal group) and anterior in 20 (13.5%, ventral group). The predominant draining vein of the inferior pancreaticoduodenal vein was the superior mesenteric vein in the ventral group (87.5%) and the FJV in the dorsal group (97.9%). Compared with the dorsal group, the ventral group had a significantly greater percentage with the superior mesenteric vein ventral to the superior mesenteric artery (30.0% versus 10.9%) and a significantly larger posterior superior pancreaticoduodenal vein diameter (3.2 ± 0.9 versus 2.7 ± 0.6 mm, p = 0.0029). These results were validated in patients with pancreatic head cancer. CONCLUSIONS: The anatomical characteristics of PD-associated vessels differed significantly between groups defined by FJV anatomy. Understanding the venous anatomy, especially the FJV, could support selection of the best approach in AFA for PD.

Rubicon can predict prognosis in patients with pancreatic ductal adenocarcinoma after neoadjuvant chemoradiotherapy.

BACKGROUND: Despite previous therapeutic studies on autophagy in cancer, its role in the treatment of pancreatic ductal adenocarcinoma remains controversial, especially regarding its effect on chemotherapy, radiotherapy, and both combined. We focused on RUN domain Beclin-1 interacting and cysteine-rich-containing protein (Rubicon) to reveal its contribution to pancreatic ductal adenocarcinoma after chemoradiotherapy. METHODS: To evaluate the clinical significance of Rubicon, immunohistochemistry was performed, and Rubicon expression was analyzed across 81 specimens resected from patients with pancreatic ductal adenocarcinoma after neoadjuvant chemoradiotherapy. A gemcitabine-resistant pancreatic ductal adenocarcinoma cell line was established followed by Rubicon expression and autophagy flux estimation. Finally, gemcitabine sensitivity, invasion ability, and cell viability were evaluated using Rubicon-targeting small interfering RNA. RESULTS: Rubicon expression in resected pancreatic ductal adenocarcinoma samples after chemoradiotherapy revealed significantly worse overall survival and recurrence-free survival in the Rubicon-high expression group than in the Rubicon-low expression group (overall survival: median [years] 2.02 vs. 3.21, p = 0.0359; recurrence-free survival: median [years] 0.90 vs. 1.90, p = 0.0146). In vitro, gemcitabine-resistant pancreatic ductal adenocarcinoma cell lines exhibited higher Rubicon expression and lower autophagy flux than the parental cell line (p < 0.01). Transduction with small interfering RNA downregulated the expression without affecting gemcitabine sensitivity, but it reduced invasion ability and cell viability (p < 0.01) in the gemcitabine-resistant pancreatic ductal adenocarcinoma cell line. CONCLUSIONS: High Rubicon expression is a significant, unfavorable prognostic factor in pancreatic ductal adenocarcinoma after neoadjuvant chemoradiotherapy. Downregulation of Rubicon expression improves invasion ability and cell viability in gemcitabine-resistant pancreatic ductal adenocarcinoma.

Tumor endothelial cell-induced CD8+ T-cell exhaustion via GPNMB in hepatocellular carcinoma.

Tumor endothelial cells (TECs) promote tumor angiogenesis and regulate cytotoxic T cells in the tumor microenvironment. However, the roles of TECs for tumor-infiltrating T-cell in hepatocellular carcinoma (HCC) is still unknown. Here, we aimed to investigate how TECs influenced tumor growth and immune responses of HCC focusing on CD8+ T-cell infiltration and exhaustion. First, TECs were isolated from subcutaneous HCC tumors with murine HCC cell lines (BNL-T) with magnetic selection of CD31+ cells, and normal endothelial cells (NECs) were isolated from normal liver. Second, immunocompetent mice were injected with BNL-T alone, BNL-T + NECs, or BNL-T + TECs for tumor formation, and the functions and exhaustion of tumor-infiltrating CD8+ T cells were evaluated. The mice injected with BNL-T + TEC showed rapid tumorigenesis and a decrease in the number of infiltrating CD8+ T cells. In addition, the percentage of CD8+ T-cell exhaustion was significantly higher in tumors from the administration of BNL-T + TEC. Third, the next-generation sequencing on TECs was performed to identify mRNAs that might be a novel treatment target. The molecule of glycoprotein nonmetastatic melanoma protein B (GPNMB) was identified and the functions of GPNMB was analyzed by silencing of GPNMB expression using small interfering RNAs. The silencing of GPNMB expression in TECs induced the suppression of tumor growth and T-cell exhaustion. In conclusion, TECs induced tumor-infiltrating T-cell exhaustion via GPNMB expression and GPNMB might be a novel therapeutic target in HCC.

Inhibition of Clusterin Represses Proliferation by Inducing Cellular Senescence in Pancreatic Cancer.

BACKGROUND: The outcome of pancreatic ductal adenocarcinoma (PDAC) is unsatisfactory, and the identification of novel therapeutic targets is urgently needed. Clinical studies on the antisense oligonucleotide that targets clusterin (CLU) expression have been conducted and have shown efficacy in other cancers. We aimed to investigate the effects of CLU in PDAC and the underlying mechanisms with a view to the clinical application of existing drugs. METHODS: We knocked down CLU in PDAC cells and evaluated changes in cell proliferation. To elucidate the mechanism responsible for these changes, we performed western blot analysis, cell cycle assay, and senescence-associated ß-galactosidase (SA-ß-gal) staining. To evaluate the clinical significance of CLU, immunohistochemistry was performed, and CLU expression was analyzed in specimens resected from PDAC patients not treated with preoperative chemotherapy. RESULTS: Knockdown of CLU significantly decreased cell proliferation and did not induce apoptosis, but did induce cellular senescence by increasing the percentage of G1-phase and SA-ß-gal staining-positive cells. A marker of DNA damage such as γH2AX and factors related to cellular senescence, such as p21 and the senescence-associated secretory phenotype, were upregulated by knockdown of CLU. CLU expression in resected PDAC specimens was located in the cytoplasm of tumor cells and revealed significantly better recurrence-free survival and overall survival in the CLU-low group than in the CLU-high group. CONCLUSIONS: We identified that CLU inhibition leads to cellular senescence in PDAC. Our findings suggest that CLU is a novel therapeutic target that contributes to the prognosis of PDAC by inducing cellular senescence.

ACAT-1-Regulated Cholesteryl Ester Accumulation Modulates Gemcitabine Resistance in Biliary Tract Cancer.

BACKGROUND: Biliary tract cancer (BTC) has few choices of chemotherapy, including gemcitabine, therefore exploring the mechanisms of gemcitabine resistance is important. We focused on lipid metabolism because biliary tract epithelial cells are essential in cholesterol and bile acid metabolism and the messenger RNA (mRNA) microarray analysis showed high acyl coenzyme A: cholesterol acyltransferase 1 (ACAT-1) expression in BTC gemcitabine-resistant (GR) cell lines. We hypothesized that aberrant accumulation of cholesteryl ester (CE) regulated by ACAT-1 could modulate GR in BTC. METHODS: CE accumulations were measured in human BTC cell lines, and the relationships between CE levels, ACAT-1 expressions, and gemcitabine sensitivity were analyzed. We performed a small-interfering RNA (siRNA)-mediated knockdown and biochemical inhibition of ACAT-1 in BTC cell lines and alterations of gemcitabine sensitivity were evaluated. To evaluate the clinical significance of ACAT-1 in regard to GR, immunohistochemistry was performed and ACAT-1 expressions were analyzed in resected BTC specimens. RESULTS: CE levels were correlated with ACAT-1 expressions and GR in four human BTC cell lines. siRNA-mediated knockdown of ACAT-1 in two independent GR cell clones as well as ACAT-1 inhibitor treatment significantly increased gemcitabine sensitivity; knockdown of ACAT-1: 5.63- and 8.02-fold; ACAT-1 inhibitor: 8.75- and 9.13-fold, respectively. ACAT-1 expression in resected BTC specimens revealed that the disease-free survival of the ACAT-1 low-intensity group (median 2.3 years) had a significantly better outcome than that of the ACAT-1 high-intensity group (median 1.1 years) under gemcitabine treatment after surgery (*p < 0.05). CONCLUSIONS: Our findings suggest that CE and ACAT-1 might be a novel therapeutic target for GR in BTC.

Preoperative FDG-Positive Lymph Nodes Predict the Postoperative Prognosis in Resectable Biliary Tract Cancers.

BACKGROUND: F-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) has been used to diagnose and stage various cancers. In regard to biliary tract cancer (BTC), due to cholangitis it is difficult to evaluate FDG uptake caused by cancer. We previously showed that FDG-positive lymph nodes (LNs) of resectable BTC had a possibility of predicting postoperative prognosis. OBJECTIVE: This study aimed to validate the usability of FDG-PET for LNs using another cohort and to investigate in detail the relationship between FDG-positive LNs and the prognosis of BTC. METHODS: We measured the preoperative maximum standardized uptake value (SUVmax) at each of the 190 surgically dissected LN areas in 67 patients and investigated the prognosis using our previously determined SUVmax cut-off values of ≥ 2.8. RESULTS: Regarding the prognosis of patients with resectable BTC, a LN SUVmax ≥ 2.8 [PET N (+)] was a poor prognostic factor for recurrence-free survival (RFS) compared with a LN SUVmax < 2.8 [PET N (-)]. It was confirmed that the hazard ratio forest plot [PET N (+)/PET N (-)] for RFS indicated a similar tendency among subcategories. Moreover, we investigated patients with pN0 disease and demonstrated that the PET N (+) group also had a significantly worse RFS outcome compared with the PET N (-) group. Recurrence of the PET N (+) group has significantly occurred more often in LNs than that of the PET N (-) group. CONCLUSION: High LN SUVmax was confirmed to be the preoperatively diagnosed prognostic risk factor for RFS in resectable BTC and could be helpful for clinical decision making regarding the perioperative treatment strategy.