Cellular senescence induction leads to progressive cell death via the INK4a-RB pathway in naked mole-rats.

Naked mole-rats (NMRs) have exceptional longevity and are resistant to age-related physiological decline and diseases. Given the role of cellular senescence in aging, we postulated that NMRs possess unidentified species-specific mechanisms to prevent senescent cell accumulation. Here, we show that upon induction of cellular senescence, NMR fibroblasts underwent delayed and progressive cell death that required activation of the INK4a-retinoblastoma protein (RB) pathway (termed "INK4a-RB cell death"), a phenomenon not observed in mouse fibroblasts. Naked mole-rat fibroblasts uniquely accumulated serotonin and were inherently vulnerable to hydrogen peroxide (H2 O2 ). After activation of the INK4a-RB pathway, NMR fibroblasts increased monoamine oxidase levels, leading to serotonin oxidization and H2 O2 production, which resulted in increased intracellular oxidative damage and cell death activation. In the NMR lung, induction of cellular senescence caused delayed, progressive cell death mediated by monoamine oxidase activation, thereby preventing senescent cell accumulation, consistent with in vitro results. The present findings indicate that INK4a-RB cell death likely functions as a natural senolytic mechanism in NMRs, providing an evolutionary rationale for senescent cell removal as a strategy to resist aging.

LINE-1 hypomethylation, increased retrotransposition and tumor-specific insertion in upper gastrointestinal cancer.

The long interspersed nuclear element-1 (LINE-1) retrotransposons are a major family of mobile genetic elements, comprising approximately 17% of the human genome. The methylation state of LINE-1 is often used as an indicator of global DNA methylation levels and it regulates the retrotransposition and somatic insertion of the genetic element. We have previously reported the significant relationship between LINE-1 hypomethylation and poor prognosis in upper gastrointestinal (GI) cancers. However, the causal relationships between LINE-1 hypomethylation, retrotransposition, and tumor-specific insertion in upper GI cancers remain unknown. We used bisulfite-pyrosequencing and quantitative real-time PCR to verify LINE-1 methylation and copy number in tissue samples of 101 patients with esophageal and 103 patients with gastric cancer. Furthermore, we analyzed the LINE-1 retrotransposition profile with an originally developed L1Hs-seq. In tumor samples, LINE-1 methylation levels were significantly lower than non-tumor controls, while LINE-1 copy numbers were markedly increased. As such, there was a significant inverse correlation between the LINE-1 methylation level and copy number in tumor tissues, with lower LINE-1 methylation levels corresponding to higher LINE-1 copy numbers. Of particular importance is that somatic LINE-1 insertions were more numerous in tumor than normal tissues. Furthermore, we observed that LINE-1 was inserted evenly across all chromosomes, and most often within genomic regions associated with tumor-suppressive genes. LINE-1 hypomethylation in upper GI cancers is related to increased LINE-1 retrotransposition and tumor-specific insertion events, which may collectively contribute to the acquisition of aggressive tumor features through the inactivation of tumor-suppressive genes.

Body Composition and Clinical Outcomes in Esophageal Cancer Patients Treated with Immune Checkpoint Inhibitors.

BACKGROUND: Obesity is associated with increased mortality in various cancers, but the relationship between obesity and clinical outcomes in unresectable or recurrent esophageal cancer who receive immune checkpoint inhibitors (ICIs) remains unknown. This study investigated the association between body composition and clinical outcomes in patients with unresectable or recurrent esophageal cancer who received ICIs. METHODS: Utilizing an unbiased database of 111 unresectable or recurrent esophageal cancers, we evaluated the relationships between body composition (body mass index, waist circumference, psoas major muscle volume, and subcutaneous and visceral fat areas) at the initiation of ICI treatment and clinical outcomes including the disease control rate and progression-free survival (PFS). RESULTS: Waist circumference was significantly associated with the disease control rate at the first assessment (P = 0.0008). A high waist circumference was significantly associated with favorable PFS in patients treated with nivolumab. In an univariable model, for 5-cm increase of waist circumference in the outcome category of PFS, univariable hazard ratio (HR) was 0.73 (95% confidence interval [CI], 0.61-0.87; P = 0.0002). A multivariable model controlling for potential confounders yielded a similar finding (multivariable HR, 0.56; 95% CI, 0.33-0.94; P = 0.027). We observed the similar finding in esophageal cancer patients treated with pembrolizumab+CDDP+5-FU (P = 0.048). In addition, waist circumference was significantly associated with the prognostic nutritional index (P = 0.0073). CONCLUSIONS: A high waist circumference was associated with favorable clinical outcomes in ICI-treated patients with unresectable or recurrent esophageal cancer, providing a platform for further investigations on the relationships among body composition, nutrition, and the immune status.

Intratumour Fusobacterium nucleatum and immune response to oesophageal cancer.

BACKGROUND: Experimental evidence suggests a role of intratumour Fusobacterium nucleatum in the aggressive behaviour of gastrointestinal cancer through downregulating anti-tumour immunity. We investigated the relationship between intratumour F. nucleatum and immune response to oesophageal cancer. METHODS: Utilising an unbiased database of 300 resected oesophageal cancers, we measured F. nucleatum DNA in tumour tissue using a quantitative polymerase chain reaction assay, and evaluated the relationship between the abundance of F. nucleatum and the densities of T cells (CD8 + , FOXP3 + and PDCD1 + ), as well as lymphocytic reaction patterns (follicle lymphocytic reaction, peritumoural lymphocytic reaction, stromal lymphocytic reaction and tumour-infiltrating lymphocytes) in oesophageal carcinoma tissue. RESULTS: F. nucleatum was significantly and inversely associated only with the peritumoural lymphocytic reaction (P = 0.0002). Compared with the F. nucleatum-absent group, the F. nucleatum-high group showed a much lower level of the peritumoural lymphocytic reaction (univariable odds ratio, 0.33; 95% confidence interval, 0.16-0.65; P = 0.0004). A multivariable model yielded a similar finding (multivariable odds ratio, 0.34; 95% confidence interval 0.16-0.69; P = 0.002). CONCLUSIONS: Intratumour F. nucleatum is associated with a diminished peritumoural lymphocytic reaction, providing a platform for further investigations on the potential interactive roles between intratumour F. nucleatum and host immunity.

Dynamic Alteration in HLA-E Expression and Soluble HLA-E via Interaction with Natural Killer Cells in Gastric Cancer.

BACKGROUND: Some reports showed the immune tolerance of soluble human leukocyte antigen E (HLA-E), but the role that soluble HLA-E plays in gastric cancer (GC) is unknown. We aimed to clarify the molecular mechanism and clinical significance of soluble HLA-E in GC. METHODS: We examined the expression of HLA-E on GC cells and soluble HLA-E under co-culture with natural killer (NK) cells in a time-dependent manner. Changes in NK cell activity were investigated using anti-NK group 2 member A (NKG2A) antibodies in the presence of soluble HLA-E. Expression of soluble HLA-E in the serum of GC patients was determined. RESULTS: Whereas HLA-E expression on GC cells peaked with interferon (IFN)-γ secretion by NK cells in a time-dependent manner, soluble HLA-E was upregulated in conditioned medium. Pre-incubation with anti-NKG2A antibodies increased the activation of NKG2A+ NK cells in the presence of soluble HLA-E. Expression of soluble HLA-E in the serum of GC patients correlated with disease progression. CONCLUSIONS: HLA-E expression dynamically changes on GC cells and in conditioned medium. Furthermore, soluble HLA-E can contribute to immune escape in GC cell lines, which may have significance in clinical practice. Moreover, soluble HLA-E may be a potential prognostic biomarker.

IL-1ß derived from mixed-polarized macrophages activates fibroblasts and synergistically forms a cancer-promoting microenvironment.

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-1ß 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.

MEK inhibition suppresses metastatic progression of KRAS-mutated gastric cancer.

Metastatic progression of tumors is driven by genetic alterations and tumor-stroma interaction. To elucidate the mechanism underlying the oncogene-induced gastric tumor progression, we have developed an organoid-based model of gastric cancer from GAstric Neoplasia (GAN) mice, which express Wnt1 and the enzymes COX2 and microsomal prostaglandin E synthase 1 in the stomach. Both p53 knockout (GAN-p53KO) organoids and KRASG12V -expressing GAN-p53KO (GAN-KP) organoids were generated by genetic manipulation of GAN mouse-derived tumor (GAN wild-type [WT]) organoids. In contrast with GAN-WT and GAN-p53KO organoids, which manifested Wnt addiction, GAN-KP organoids showed a Wnt-independent phenotype and the ability to proliferate without formation of a Wnt-regulated three-dimensional epithelial architecture. After transplantation in syngeneic mouse stomach, GAN-p53KO cells formed only small tumors, whereas GAN-KP cells gave rise to invasive tumors associated with the development of hypoxia as well as to liver metastasis. Spatial transcriptomics analysis suggested that hypoxia signaling contributes to the metastatic progression of GAN-KP tumors. In particular, such analysis identified a cluster of stromal cells located at the tumor invasive front that expressed genes related to hypoxia signaling, angiogenesis, and cell migration. These cells were also positive for phosphorylated extracellular signal-regulated kinase (ERK), suggesting that mitogen-activated protein kinase (MAPK) signaling promotes development of both tumor and microenvironment. The MEK (MAPK kinase) inhibitor trametinib suppressed the development of GAN-KP gastric tumors, formation of a hypoxic microenvironment, tumor angiogenesis, and liver metastasis. Our findings therefore establish a rationale for application of trametinib to suppress metastatic progression of KRAS-mutated gastric cancer.

PD-L1 and PD-L2 expression status in relation to chemotherapy in primary and metastatic esophageal squamous cell carcinoma.

Immune checkpoint inhibitors have shown efficacy in various cancers. Although programmed death ligand 1/2 (PD-L1/L2) expressions have been demonstrated as predictive biomarkers of response to immune checkpoint inhibitors and prognostic markers, whether PD-L1/L2 expression is altered in esophageal squamous cell carcinoma during the therapeutic course is unclear. Whether PD-L1/L2 expression in metastatic or recurrent lesions is consistent with that in primary tumors is also unknown. This study included 561 surgically resected esophageal squamous cell carcinomas and PD-L1/L2 expression was evaluated by immunohistochemistry. We investigated the influence of chemotherapeutic drugs (cisplatin and fluorouracil) on PD-L1/L2 expression and PD-L1/L2-related pathways in vitro. We also examined PD-L1/L2 expression in 18 surgically resected lymph node metastases and 10 recurrent lesions compared with primary lesions. The positive rate of PD-L1 was significantly higher in patients with preoperative chemotherapy than in those without preoperative therapy. The positive rate of PD-L2 expression showed no significant difference between patient groups. Cisplatin increased PD-L1 expression in cancer cell lines in vitro, but decreased PD-L2 in some cell lines. The effects of cisplatin on phosphorylated signal transducer and activator of transcription 1/3 (pSTAT1/3) also differed depending on cell lines. Fluorouracil increased PD-L1 and PD-L2 expression. PD-L1/L2 expression in lymph node metastases and recurrent lesions did not always match expression in primary lesions. PD-L1/L2 expression may be altered by preoperative chemotherapy, and PD-L1 /L2 expression in primary lesions does not always match that of metastatic/recurrent lesions. Thus, one-time evaluation is not sufficient to evaluate PD-L1/L2 expression as a biomarker in esophageal cancer.

Tumor microenvironmental 15-PGDH depletion promotes fibrotic tumor formation and angiogenesis in pancreatic cancer.

The arachidonic acid cascade is a major inflammatory pathway that produces prostaglandin E2 (PGE2). Although inhibition of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is reported to lead to PGE2 accumulation, the role of 15-PGDH expression in the tumor microenvironment remains unclear. We utilized Panc02 murine pancreatic cancer cells for orthotopic transplantation into wild-type and 15-pgdh+/- mice and found that 15-pgdh depletion in the tumor microenvironment leads to enhanced tumorigenesis accompanied by an increase in cancer-associated fibroblasts (CAFs) and the promotion of fibrosis. The fibrotic tumor microenvironment is widely considered to be hypovascular; however, we found that the angiogenesis level is maintained in 15-pgdh+/- mice, and these changes were also observed in a genetically engineered PDAC mouse model. Further confirmation revealed that fibroblast growth factor 1 (FGF1) is secreted by pancreatic cancer cells after PGE2 stimulation, consequently promoting CAF proliferation and vascular endothelial growth factor A (VEGFA) expression in the tumor microenvironment. Finally, in 15-pgdh+/- Acta2-TK mice, depletion of fibroblasts inhibited angiogenesis and cancer cell viability in orthotopically transplanted tumors. These findings highlighted the role of 15-pgdh downregulation in enhancing PGE2 accumulation in the pancreatic tumor microenvironment and in subsequently maintaining the angiogenesis level in fibrotic tumors along with CAF expansion.

Clinical Significance of Pretreatment Red Blood Cell Distribution Width as a Predictive Marker for Postoperative Morbidity After Esophagectomy for Esophageal Cancer: A Retrospective Study.

BACKGROUND: Clinical significance of red blood cell distribution (RDW) as a predictive marker for the incidence of postoperative morbidity after esophagectomy for esophageal cancer has not been established. METHODS: This study included 634 consecutive patients who underwent three-incisional esophagectomy with lymphadenectomy for esophageal cancer between April 2005 and November 2020. Correlation between pretreatment RDW and patient background, cancer background, and short-term outcome after esophagectomy were retrospectively investigated. RESULTS: Eighty patients (12.6%) had a high pretreatment RDW (> 14.2), which correlated with malnutrition estimated by body mass index, hemoglobin, total lymphocyte count, albumin, and total cholesterol. High pretreatment RDW was an independent risk factor for postoperative severe morbidity of grade IIIb or higher based on the Clavien-Dindo classification (hazard ratio [HR] 3.90, 95% confidence interval [CI] 1.707-8.887; p = 0.0012) and reoperation (HR 4.39, 95% CI 1.552-12.390; p = 0.0053) after open esophagectomy (OE). However, RDW was not associated with postoperative morbidity incidence after minimally invasive esophagectomy (MIE). CONCLUSIONS: Pretreatment RDW may be a surrogate marker for nutritional status and could be a predictive marker for postoperative severe morbidity, reoperation, and possibly pneumonia after OE. On the contrary, the lower invasiveness of MIE may have reduced the effect of pretreatment malnutrition on morbidity incidence, which could explain the insignificant relationship between RDW and poor short-term outcomes in MIE.

Preoperative Smoking Cessation and Prognosis After Curative Esophagectomy for Esophageal Cancer: A Cross-Sectional Study.

BACKGROUND: Several cohort studies have reported that post-esophagectomy morbidities may worsen prognosis. Smoking cessation is an effective prophylactic measure for reducing post-esophagectomy morbidity; however, whether smoking cessation can contribute to the improvement of prognosis is unknown due to the absence of reliable databases covering the cessation period. This study aimed to elucidate whether sufficient preoperative smoking cessation can improve prognosis after esophageal cancer surgery by reducing post-esophagectomy morbidity. METHODS: This study included 544 consecutive patients who underwent curative McKeown and Ivor-Lewis esophagectomies for esophageal cancer between May 2011 and June 2021. Data on smoking status and cessation period were prospectively accumulated. Survival data were finally updated on 30 January 2022. Receiver operating characteristic curve analysis for the cut-off value of appropriate cessation period in reducing post-esophagectomy respiratory morbidity as well as analyses for the association of cessation period with short- and long-term outcomes were performed. RESULTS: Post-esophagectomy morbidity significantly diminished overall survival (OS) after esophagectomy (p = 0.0003). A short preoperative smoking cessation period of ≤ 2 months was associated with frequent post-esophagectomy morbidity of Clavien-Dindo classification ≥IIIb (p = 0.0059), pneumonia (p = 0.016), respiratory morbidity (p = 0.0057), and poor OS in clinical stages II and III (p = 0.0015). Moreover, it was an independent factor for poor OS (hazard ratio 1.85, 95% confidence interval 1.068-3.197; p = 0.028), along with body mass index <18.5 and R1 resection. CONCLUSIONS: Sufficient preoperative smoking cessation > 2 months may be effective in improving not only short-term outcomes but also prognosis after esophagectomy for locally advanced esophageal cancer.

Intracellular MUC20 variant 2 maintains mitochondrial calcium homeostasis and enhances drug resistance in gastric cancer.

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.

Impact of Type of Gastrectomy on Death from Pneumonia in Elderly Patients with Gastric Cancer Over the Long Term.

BACKGROUND: Gastrectomy may induce significant postoperative disabilities and worsen the quality of life in elderly patients. Without a functioning esophagogastric junction (EGJ), swallowing is impaired because of the anatomical and physiological changes after surgery, which increases the risk of postoperative pneumonia. The aim of this study was to identify the impact of the type of surgical procedure on death from pneumonia in elderly patients with gastric cancer (GC) over the long term. METHODS: We analyzed the data of 343 patients with GC who underwent curative gastrectomy in our hospital. We divided the patients into elderly and non-elderly groups. Among them, 109 patients aged ≥ 75 years who underwent curative resection were analyzed, their clinicopathological factors and clinical outcomes were compared, and the impact of the type of surgical procedure on death from pneumonia over the long term was evaluated. The institutional scientific review board of Kumamoto University Hospital was approved for data collection and analysis (No. 1037). RESULTS: There were significantly higher levels of American Society of Anesthesiologists (ASA) and poor nutrition in the elderly group; however, gender, BMI and factors related to pneumonia did not differ significantly between groups. The median duration of follow-up time 1588 days. On the multivariate analysis, age and surgical procedure were selected as independent predictive factors for pneumonia-related survival. CONCLUSION: Preservation of the EGJ as much as possible while maintaining curability is useful for reducing postoperative death from pneumonia over the long term in elderly patients with gastric cancer.

Clinicopathological characteristics and prognosis of poorly cohesive cell subtype of gastric cancer.

BACKGROUND: The new World Health Organization (WHO) classification of gastric cancer includes a histological subtype of poorly cohesive carcinoma (PCC), which includes signet-ring cell (SRC) phenotype. We aimed to examine the concordance between preoperative clinical and postoperative histological diagnoses according to the 2010 WHO histological subtypes and to compare the prognoses of these subtypes. METHODS: The study cohort comprised 665 patients who underwent gastrectomy from 2005 to 2019. Histological subtypes were classified into PCC-NOS (non-signet ring cell subtype), SRC, and non-PCC, which were defined by the predominant component in accordance with the 2010 WHO classification of gastric cancer. The concordance of clinical and pathological diagnosis was examined and clinicopathological characteristics and survival outcome of the three subtypes compared. RESULTS: The cancers of 443 patients (66.7%) were classified as non-PCC, of 112 patients (16.8%) as PCC-NOS, and of 110 patients (16.5%) as SRC predominant subtypes. Significant differences in sex, age, tumor location, size, macroscopic type, and pathological TNM category (all P<0.05) were found. The concordance rate of preoperative and postoperative histological subtypes was significantly lower for poorly cohesive than other subtypes (P<0.0001). Preoperative stage tended to be underestimated for PCC-NOS subtype and these patients had poorer overall survival than those with the other two subtypes (P=0.005). Multivariate logistic regression analysis of overall survival showed that WHO histological subtype (PCC-NOS vs. non-PCC/SRC, HR: 1.64, 95% CI: 1.18-2.29, P=0.0034) was a significant independent prognostic factor. CONCLUSION: Our results suggest that poorly cohesive carcinoma subtypes have different biological characteristics and prognoses.

Relationship between Fusobacterium nucleatum and antitumor immunity in colorectal cancer liver metastasis.

Fusobacterium nucleatum has been detected in 8%-13% of human colorectal cancer, and shown to inhibit immune responses against primary colorectal tumors in animal models. Thus, we hypothesized that the presence of F. nucleatum might be associated with reduced T cell density in colorectal cancer liver metastases (CRLM). We quantified F. nucleatum DNA in 181 CRLM specimens using quantitative PCR assay. The densities of CD8+ T cells, CD33+ cells (marker for myeloid-derived suppressor cells [MDSCs]), and CD163+ cells (marker for tumor-associated macrophages [TAMs]) in CRLM tissue were determined by immunohistochemical staining. Fusobacterium nucleatum was detected in eight (4.4%) of 181 CRLM specimens. Compared with F. nucleatum-negative CRLM, F. nucleatum-positive CRLM showed significantly lower density of CD8+ T cells (P = .033) and higher density of MDSCs (P = .001). The association of F. nucleatum with the density of TAMs was not statistically significant (P = .70). The presence of F. nucleatum is associated with a lower density of CD8+ T cells and a higher density of MDSCs in CRLM tissue. Upon validation, our findings could provide insights to develop strategies that involve targeting microbiota and immune cells for the prevention and treatment of CRLM.

Trastuzumab upregulates programmed death ligand-1 expression through interaction with NK cells in gastric cancer.

BACKGROUND: The predictive significance of programmed death ligand 1 (PD-L1) for programmed death 1 (PD-1) inhibitors remains unclear in gastric cancer (GC) due to the dynamic alteration by treatments. We aimed to elucidate the effects of trastuzumab (Tmab) on PD-L1 expression in GC. METHODS: PD-L1 expression was evaluated by multicolour flow cytometry analysis after co-culturing GG cell lines and immune cells with Tmab. IFN-γ in the co-culture experiments was quantified. Immunohistochemistry (IHC) for PD-L1 expression using clinical samples was also performed to confirm PD-L1 alteration by Tmab. RESULTS: PD-L1 expression was significantly upregulated by Tmab in HER2-amplified GC cell lines co-cultured with peripheral blood mononuclear cells (PBMCs). PD-L1 upregulation by Tmab was also observed in the GC cells co-cultured with NK cells in time-dependent manner, but not with monocytes. IFN-γ concentration in conditioned media from co-cultured PBMCs and NK cells with Tmab was significantly higher and anti-IFN-γ significantly suppress the Tmab-induced PD-L1 upregulation. IHC also suggested PD-L1 upregulation after Tmab treatment. CONCLUSIONS: Tmab can upregulate PD-L1 expression on GC cells through interaction with NK cells. These results suggest clinical implications in the assessment of the predictive significance of PD-L1 expression for PD-1 inhibitors.

Fusobacterium nucleatum confers chemoresistance by modulating autophagy in oesophageal squamous cell carcinoma.

BACKGROUND: Fusobacterium nucleatum (F. nucleatum) is a gut microbe implicated in gastrointestinal tumorigenesis. Predicting the chemotherapeutic response is critical to developing personalised therapeutic strategies for oesophageal cancer patients. The present study investigated the relationship between F. nucleatum and chemotherapeutic resistance in oesophageal squamous cell carcinoma (ESCC). METHODS: We examined the relationship between F. nucleatum and chemotherapy response in 120 ESCC resected specimens and 30 pre-treatment biopsy specimens. In vitro studies using ESCC cell lines and co-culture assays further uncovered the mechanism underlying chemotherapeutic resistance. RESULTS: ESCC patients with F. nucleatum infection displayed lesser chemotherapeutic response. The infiltration and subsistence of F. nucleatum in the ESCC cells were observed by transmission electron microscopy and laser scanning confocal microscopy. We also observed that F. nucleatum modulates the endogenous LC3 and ATG7 expression, as well as autophagosome formation to induce chemoresistance against 5-FU, CDDP, and Docetaxel. ATG7 knockdown resulted in reversal of F. nucleatum-induced chemoresistance. In addition, immunohistochemical studies confirmed the correlation between F. nucleatum infection and ATG7 expression in 284 ESCC specimens. CONCLUSIONS: F. nucleatum confers chemoresistance to ESCC cells by modulating autophagy. These findings suggest that targeting F. nucleatum, during chemotherapy, could result in variable therapeutic outcomes for ESCC patients.

Inflammation-Induced Tumorigenesis and Metastasis.

Inflammation, especially chronic inflammation, plays a pivotal role in tumorigenesis and metastasis through various mechanisms and is now recognized as a hallmark of cancer and an attractive therapeutic target in cancer. In this review, we discuss recent advances in molecular mechanisms of how inflammation promotes tumorigenesis and metastasis and suppresses anti-tumor immunity in various types of solid tumors, including esophageal, gastric, colorectal, liver, and pancreatic cancer as well as hematopoietic malignancies.

Functional diversity of cancer-associated fibroblasts in modulating drug resistance.

The effectiveness of current chemotherapies for cancer is gradually progressing; however achieving a complete cure through chemotherapy is still difficult and has been the main goal in treatment of advanced cancer. Drug resistance is an issue in cancer therapy, therefore increasing numbers of investigations into drug resistance have focused on the characteristics of the cancer cells themselves. The interaction between the tumor microenvironment (TME) and cancer cells is also intimately involved in the development of drug resistance. Cancer-associated fibroblasts (CAFs) are a predominant component of the TME and affect tumor progression by secreting soluble factors. This review summarizes the most up-to-date knowledge of CAFs and drug resistance in cancer, with a focus on factors secreted from CAFs including proteins, cytokines, extracellular vesicles, and metabolites. A perspective on the potential role of anti-CAF therapies in overcoming CAF-induced drug resistance is also discussed.

Tumor immune microenvironment and immune checkpoint inhibitors in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is the main prevalent histological type of esophageal cancer, predominantly constituting 90% of cases worldwide. Despite the development of multidisciplinary therapeutic approaches, its prognosis remains unfavorable. Recently, the development of monoclonal antibodies inhibiting programmed death 1 (PD-1) or programmed death-ligand 1 (PD-L1) has led to marked therapeutic responses among multiple malignancies including ESCC. However, only a few patients achieved clinical benefits due to resistance. Therefore, precise and accurate predictive biomarkers should be identified for personalized immunotherapy in clinical settings. Because the tumor immune microenvironment can potentially influence the patient's response to immune checkpoint inhibitors, tumor immunity, such as PD-L1 expression on tumors, tumor-infiltrating lymphocytes, tumor-associated macrophages, and myeloid-derived suppressor cells, in ESCC should be further investigated. In this review, accumulated evidence regarding the tumor immune microenvironment and immune checkpoint inhibitors in ESCC are summarized.