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Hepatocellular carcinoma (HCC) is the second leading cause of cancer‐related death. High recurrence rates after curative resection and the lack of specific biomarkers for intrahepatic metastases are major clinical problems. Recently, exosomal microRNAs (miRNAs) have been reported to have a role in the formation of the pre‐metastatic niche and as promising biomarkers in patients with malignancy. Here we aimed to clarify the molecular mechanisms of intrahepatic metastasis and to identify a novel biomarker miRNA in patients with HCC. A highly intrahepatic metastatic cell line (HuH‐7M) was established by in vivo selection. HuH‐7M showed increased proliferative ability and suppression of apoptosis and anoikis. HuH‐7M and the parental cell (HuH‐7P) showed the similar expression of epithelial‐mesenchymal transition markers and cancer stem cell markers. In vivo, mice treated with exosomes derived from HuH‐7M showed increased tumorigenesis of liver metastases. Exosomes from HuH‐7M downregulated endothelial cell expression of vascular endothelial‐cadherin (VE‐cadherin) and zonula occludens‐1 (ZO‐1) in non‐cancerous regions of liver and increased the permeability of FITC‐dextran through the monolayer of endothelial cells. The miRNAs (miR‐638, miR‐663a, miR‐3648, and miR‐4258) could attenuate endothelial junction integrity by inhibiting VE‐cadherin and ZO‐1 expression. In patients with HCC, higher serum exosomal miR‐638 expression was associated with tumor recurrence. In conclusion, the miRNAs secreted from a highly metastatic cancer cell can promote vascular permeability via downregulation of endothelial expression of VE‐cadherin and ZO‐1. Serum exosomal miR‐638 expression holds potential for serving as a significant and independent prognostic marker in HCC. miR‐638, miR‐663a, miR‐3648, and miR‐4258 downregulate VE‐cadherin and ZO‐1 expression in HUVECs.

Desmoplastic reaction is a fibrosis reaction that is characterized by a large amount of dense extracellular matrix (ECM) and dense fibrous stroma. Fibrotic stroma around the tumor has several different components, including myofibroblasts, collagen, and other ECM molecules. This stromal reaction is a natural response to the tissue injury process, and fibrosis formation is a key factor in pancreatic cancer development. The fibrotic stroma of pancreatic cancer is associated with tumor progression, metastasis, and poor prognosis. Reportedly, multiple processes are involved in fibrosis, which is largely associated with the upregulation of various cytokines, chemokines, matrix metalloproteinases, and other growth factors that promote tumor growth and metastasis. Fibrosis is also associated with immunosuppressive cell recruitment, such as regulatory T cells (Tregs) with suppressing function to antitumor immunity. Further, dense fibrosis restricts the flow of nutrients and oxygen to the tumor cells, which can contribute to drug resistance. Furthermore, the dense collagen matrix can act as a physical barrier to block the entry of drugs into the tumor, thereby further contributing to drug resistance. Thus, understanding the mechanism of desmoplastic reaction and fibrosis in pancreatic cancer will open an avenue to innovative medicine and improve the prognosis of patients suffering from this disease. Desmoplastic reaction is a phenomenon seen in many cancers, including pancreatic cancer. It occurs when the tumor invades the surrounding tissues, causing an inflammatory response that leads to fibrosis.

Background Predictive factors of nivolumab treatment response in patients with gastric cancer (GC) remain unclear. Methods In this retrospective cohort study, tissue specimens of patients with unresectable or recurrent GC and prior or scheduled treatment with nivolumab as third-line or higher therapy between September 2017 and February 2019 were collected from 23 institutions. The tumour-positive score (TPS) and combined positive score (CPS) of PD-L1 expression and mismatch repair (MMR) were analysed by immunohistochemistry. Associations between clinicopathological factors and tumour-response rate, hyperprogressive disease (HPD) rate and survival were assessed. Results Of 200 eligible patients, 143 had measurable lesions. The response and HPD rates were 17.5% and 22.1%, respectively. The response rate was significantly higher in patients with performance status (PS) 0–1 ( P  = 0.026), non-peritoneal metastasis ( P  = 0.021), PD-L1 TPS ≥ 1 ( P  = 0.012), CPS ≥ 5 ( P  = 0.007) or ≥ 10 ( P  < 0.001) or MMR deficiency ( P  < 0.001). The HPD rate was significantly higher in patients with PS 2–3 ( P  = 0.026), liver metastasis ( P  < 0.001) and CPS < 10 ( P  = 0.048). Multivariate analysis revealed that CPS ( P  = 0.001) and MMR ( P  = 0.002) were independent prognostic factors of progression-free survival, as well as liver metastasis ( P  < 0.001), peritoneal metastasis ( P  = 0.004) and CRP ( P  < 0.001). Conclusions PD-L1 CPS and MMR could be useful biomarkers for nivolumab treatment efficacy in GC. Clinical trial registration UMIN000032164.

Dickkopf1 (DKK1) is overexpressed in various cancers and promotes cancer cell proliferation by binding to cytoskeleton-associated protein 4 (CKAP4). However, the mechanisms underlying DKK1 expression are poorly understood. RNA sequence analysis revealed that expression of the transcription factor forkhead box M1 (FOXM1) and its target genes concordantly fluctuated with expression of DKK1 in pancreatic ductal adenocarcinoma (PDAC) cells. DKK1 knockdown decreased FOXM1 expression and vice versa in PDAC and esophageal squamous cell carcinoma (ESCC) cells. Inhibition of either the DKK1-CKAP4-AKT pathway or the ERK pathway suppressed FOXM1 expression, and simultaneous inhibition of both pathways showed synergistic effects. A FOXM1 binding site was identified in the 5ʹ-untranslated region of the DKK1 gene, and its depletion decreased DKK1 expression and cancer cell proliferation. Clinicopathological and database analysis revealed that PDAC and ESCC patients who simultaneously express DKK1 and FOXM1 have a poorer prognosis. Multivariate analysis demonstrated that expression of both DKK1 and FOXM1 is the independent prognostic factor in ESCC patients. Although it has been reported that FOXM1 enhances Wnt signaling, FOXM1 induced DKK1 expression independently of Wnt signaling in PDAC and ESCC cells. These results suggest that DKK1 and FOXM1 create a positive feedback loop to promote cancer cell proliferation.

BackgroundThe Charlson Comorbidity Index (CCI), an indicator that objectively quantifies comorbidities, reduces nutritional status; however, the impact of the CCI on the postoperative nutrition indexes of patients with esophageal cancer remains unclear.MethodsIn total, 336 patients with esophageal cancer who underwent surgery between January 2011 and April 2017 were included in this study. We investigated the relationship between the CCI and postoperative nutrition indexes.ResultsPatients were divided into two groups: CCI ≤1 (low CCI group) and CCI ≥2 (high CCI group). A high CCI was significantly associated with shortened overall survival (OS; 3-year OS rate of 77.9% in the low CCI group versus 59.7% in the high CCI group; p = 0.008). Nutritional indexes, such as the Prognostic Nutritional Index (PNI), at 1 month after esophagectomy were significantly lower in the high CCI group than in the low CCI group (p = 0.031); however, the PNI at 6 months after surgery was similar between the high and low CCI groups. Multivariate analysis identified high CCI as an independent risk factor associated with PNI <45 in esophageal cancer patients at 1 month after esophagectomy (p = 0.047).ConclusionThis study showed that CCI ≥2 was significantly associated with poor PNI at 1 month after surgery for esophageal cancer, indicating that it is necessary to administer effective nutritional interventions for patients with postoperative malnutrition, especially those with multiple comorbidities.

Early detection of pancreatic ductal adenocarcinoma (PDAC) is essential for improving patient survival rates, and noninvasive biomarkers are urgently required to identify patients who are eligible for curative surgery. Here, we examined extracellular vesicles (EVs) from the serum of PDAC patients to determine their ability to detect early‐stage disease. EV‐associated proteins purified by ultracentrifugation and affinity columns underwent proteomic analysis to identify novel PDAC markers G protein‐coupled receptor class C group 5 member C (GPRC5C) and epidermal growth factor receptor pathway substrate 8 (EPS8). To verify the potency of GPRC5C‐ or EPS8‐positive EVs as PDAC biomarkers, we analyzed EVs from PDAC patient blood samples using ultracentrifugation in two different cohorts (a total of 54 PDAC patients, 32 healthy donors, and 22 pancreatitis patients) by immunoblotting. The combination of EV‐associated GPRC5C and EPS8 had high accuracy, with area under the curve values of 0.922 and 0.946 for distinguishing early‐stage PDAC patients from healthy controls in the two cohorts, respectively, and could detect PDAC patients who were negative for CA19‐9. Moreover, we analyzed 30 samples taken at three time points from 10 PDAC patients who underwent surgery: before surgery, after surgery, and recurrence as an early‐stage model. These proteins were detected in EVs derived from preoperative and recurrence samples. These results indicated that GPRC5C‐ or EPS8‐positive EVs were biomarkers that have the potential to detect stage I early pancreatic cancer and small recurrent tumors detected by computed tomography. Early detection of pancreatic ductal adenocarcinoma (PDAC) is essential for improving patient survival rates. This study demonstrated that PDAC patients who were negative for CA19‐9 could be detected by extracellular vesicles (EV)‐associated GPRC5C or EPS8, and these EV‐associated proteins showed high accuracy for distinguishing patients with stage I early pancreatic cancer from healthy controls. EV‐associated GPRC5C and EPS8 will contribute to the early detection and help in the design of potential curative surgical options.

The biological significance of micro (mi)RNAs has traditionally been evaluated according to their RNA expression levels based on the assumption that miRNAs recognize and regulate their targets in an unvarying fashion. Here we show that a fraction of mature miRNAs including miR-17-5p, -21-5p, and -200c-3p and let-7a-5p harbor methyl marks that potentially alter their stability and target recognition. Importantly, methylation of these miRNAs was significantly increased in cancer tissues as compared to paired normal tissues. Furthermore, miR-17-5p methylation level in serum samples distinguished early pancreatic cancer patients from healthy controls with extremely high sensitivity and specificity. These findings provide a basis for diagnostic strategies for early-stage cancer and add a dimension to our understanding of miRNA biology. In cancer it is assumed that microRNAs recognise and regulate their targets uniformly. Here, the authors show that in gastrointestinal cancers methylation of microRNAs may impact their stability, and that levels of microRNA methylation are distinct in pancreatic cancer patients compared to healthy controls with potential diagnostic implications.

The cancer drug gemcitabine (GEM) is a key drug for treating pancreatic ductal adenocarcinoma (PDAC), but PDAC cells develop chemoresistance after long-term administration. Since the tolerance was immediately spread to every PDAC tissue in a patient, it is assumed that some certain efficient mechanisms underlay in the development of chemoresistance. Changes in the levels of particular microRNAs or alterations in intercellular communication play a dominant role in chemoresistance development, and recent data also suggest that exosomes play an important role in this process. In this study, we revealed that the loop conferred chemoresistance in PDAC cells. The loop was as follows; 1, The long-term exposure of GEM increased miR-155 expression in PDAC cells. 2, The increase of miR-155 induced two different functions; exosome secretion and chemoresistance ability via facilitating the anti-apoptotic activity. 3, Exosome deliver the miR-155 into the other PDAC cells and induce the following function. The target therapy to miR-155 or the exosome secretion effectively attenuated the chemoresistance, and these results were validated with both clinical samples and in vivo experiments. This mechanism represents a novel therapeutic target in GEM treatment to PDAC.

BackgroundTertiary lymphoid structures (TLSs) are ectopic lymphoid aggregates in non-lymphoid tissues, which are associated with improved prognosis in some cancer types. This study aimed to investigate the clinical significance of TLSs in oesophageal cancer (EC).MethodsIn a series of 316 EC surgical specimens from two different institutes, we evaluated the density and maturity of peritumoral TLSs using haematoxylin/eosin, immunohistochemistry, and multiplex immunofluorescence staining. We analysed the association between TLSs and clinicopathological parameters. The clinical significance of TLSs was further evaluated in a different cohort of 34 patients with recurrent EC treated with anti-PD-1 antibody.ResultsTumours with high TLS density predominantly consisted of matured TLSs. High TLS density was significantly associated with less advanced tumour stage, absence of lymphatic/vascular invasion, better serum nutrition parameters (neutrophils count, albumin, neutrophil-to-lymphocyte ratio, and prognostic nutritional index), and prolonged survival. This survival trend was more remarkable in cases with matured TLSs, which represented an increased population of CD138+ plasma cells. In the second EC cohort, TLS density predicted the clinical response to anti-PD-1 antibody and patient survival.ConclusionThe density and maturity of peritumoral TLSs are useful parameters for predicting long-term survival and response to anti-PD-1 antibody treatment in EC patients.