[The Evaluation of Neoadjuvant Chemotherapy for Locally Advanced Rectal Cancer].

We evaluated the efficacy of neoadjuvant chemotherapy(NAC)for 38 patients with locally advanced rectal cancer (LARC). We administered mFOLFOX6 in 15, FOLFIRI in 3, CAPOX in 10, IRIS in 1 and FOLFOXIRI in 9 patients. We also used bevacizumab in 31 and panitumumab in 7 patients. There were 27 male and 11 female patients, with a median age of 64 years, and location was RS 2, Ra 9, Rb 21, and P 6. Synchronous distant metastasis was recognized in 13 patients. Nine patients had suffered adverse event of Grade 3, however all patients could complete NAC. Clinical response was CR 3, PR 31, SD 4, response rate was 91.9%, and reduction rate was 43.3(range 18.8-100)%. Clinical response of distant metastasis was CR 3, PR 9 and SD 1. Laparoscopic surgery was performed in 29 patients. Postoperative complications of Grade 2 of Clavien- Dindo classification were recognized in 14 and Grade 3 in 4 patients. Three- and five-year overall survival rate of 25 patients without distant metastasis were 79.6% and 74.9%, respectively; and 13 with distant metastasis were 61.6% and 52.6%, respectively. The efficacy, safety and postoperative outcomes of NAC for LARC are favorable, and we think that NAC will be one of the treatments for LARC.

ARID1A deficiency in EBV-positive gastric cancer is partially regulated by EBV-encoded miRNAs, but not by DNA promotor hypermethylation.

AT-rich interactive domain 1A (ARID1A), which is a tumor suppressor gene, is frequently mutated in Epstein-Barr virus-positive gastric cancer [EBV (+) GC]. While most ARID1A mutations in GC are truncating mutations, leading to loss of ARID1A protein expression, epigenetic modifications appear to contribute to ARID1A deficiency in EBV (+) GC harboring wild-type ARID1A. Based on the significant role of epigenetic modifications in EBV (+) GC that contributes to ARID1A deficiency, the methylation status of ARID1A was evaluated in EBV-infected cells and GC patients using a publicly available microarray and the Cancer Genome Atlas (TCGA) database. EBV-encoded miRNAs that potentially target ARID1A were identified as an additional epigenetic modulator by computational prediction. In vitro experiments were conducted to evaluate how EBV-encoded miRNAs affected ARID1A mRNA and protein levels. In clinical GC samples, the expression of predicted miRNAs and ARID1A and the mutation status of ARID1A was evaluated. As results, ARID1A was not hypermethylated in EBV (+) GC samples or EBV-infected GC cells. EBV infection did not alter ARID1A mRNA levels, suggesting that ARID1A protein deficiency was caused by post-transcriptional gene silencing in ARID1A-WT EBV (+) GC. Overexpression of miR-BART11-3p and miR-BART12, which were identified as miRNAs that potentially bind ARID1A, suppressed ARID1A protein expression in MKN7 and NCI-N87 cells. Highly expressed miR-BART11-3p and miR-BART12 were correlated with decreased ARID1A levels in GC tumors which did not harbor ARID1A mutations. The present findings revealed that ARID1A expression was epigenetically regulated by miR-BART11-3p and miR-BART12 in EBV (+) GC.

Selective sensitivity of EZH2 inhibitors based on synthetic lethality in ARID1A-deficient gastric cancer.

BACKGROUND: AT-rich interactive domain 1A (ARID1A) is a tumor suppressor gene that is frequently mutated in gastric cancer (GC). Although ARID1A mutations are not a druggable target for conventional treatments, novel therapeutic strategies based on a synthetic lethal approach are effective for ARID1A-deficient cancers. The histone methyltransferase EZH2 acts in a synthetic lethal manner in ARID1A-mutated ovarian cancer, although its role in GC remains unknown. METHODS: The selective sensitivity of the EZH2 inhibitors for ARID1A-deficient GC cells was evaluated using cell viability and colony formation assays. The expression of PI3K/AKT signaling genes were investigated using TCGA's cBioPortal database to determine whether the homeostasis between ARID1A and EZH2 is related to cell proliferation and survival via the PI3K/AKT signaling pathway. We also evaluated the phosphorylation of PI3K/AKT signaling proteins in ARID1A knock downed ARID1A-WT GC cells. RESULTS: EZH2 inhibitors decreased the viability of ARID1A-deficient cells in a dose-dependent manner and demonstrated the selective sensitivity to ARID1A-deficient cells in vitro experiment system. Bioinformatics approach revealed that the PI3K/AKT signaling was tended to be activated in ARID1A-deficient GC enhancing cell viability and, furthermore, down-regulation of EZH2 in ARID1A-deficient GC was related to normalization of PI3K/AKT signaling pathway. The cell experiment revealed that phosphorylated AKT was upregulated in ARID1A-deficent GC cells. CONCLUSIONS: The present findings provide a rationale for the selective sensitivity of EZH2 inhibitors against ARID1A-deficient GC and suggest the potential efficacy of targeted therapy using EZH2 inhibitors in this patient population.

KRT17 as a prognostic biomarker for stage II colorectal cancer.

Adjuvant chemotherapy is considered for patients with stage II colorectal cancer (CRC) characterized by poor prognostic clinicopathological features; however, current stratification algorithms remain inadequate for identifying high-risk patients. To develop prognostic assays, we conducted a step-wise screening and validation strategy using nine cohorts of stage II patients based on multiple platforms, including microarray, RNA-sequencing (RNA-seq) and immunohistochemistry (IHC) on formalin-fixed paraffin-embedded (FFPE) tissues. Four microarray datasets (total n = 458) were used as the discovery set to screen for single genes associated with postoperative recurrence. Prognostic values of candidate genes were evaluated in three independent microarray/RNA-seq validation cohorts (n = 89, n = 93 and n = 183, respectively), and then IHC for KRT17 was conducted in two independent FFPE series (n = 110 and n = 44, respectively). We found that high levels of KRT17 transcript expression were significantly associated with poor relapse-free survival (RFS) not only in the discovery set, but also in three validation cohorts, and its prognostic impact was independent of conventional factors by multivariate analyses. Positive staining of KRT17 protein was significantly associated with poor RFS in two independent FFPE cohorts. KRT17 protein expression had independent prognostic impact on RFS in a multivariate model adjusted for conventional variables, including high-risk clinicopathological features. In conclusion, using nine independent cohorts consisting of 997 stage II patients, we identified and validated the expression of KRT17 transcript and KRT17 protein as a robust prognostic biomarker that can discriminate postoperative stage II patients who are at high probability of disease recurrence, providing additional prognostic stratification beyond the currently available high-risk factors.

Characterization of tumor-infiltrating immune cells in relation to microbiota in colorectal cancers.

BACKGROUND: Several articles have recently reported that certain colon microbiota can improve the efficacy of cancer immunotherapy. To develop new treatment strategies, including immunotherapy for colorectal cancer (CRC), we evaluated the correlations between subpopulations of tumor-infiltrating immune cells (TIICs) and intestinal microbiota in CRC. METHODS: Fresh surgically resected specimens, formalin-fixed paraffin-embedded whole tissue samples, and stool samples were collected. TIICs including Tregs, Th17 cells and tumor-associated macrophages (TAMs) in the surgically resected specimens were analyzed using flow cytometry. FOXp3, CD8, CD163, and phosphorylated-STAT1-positive TIICs in the whole tissue samples were analyzed using IHC, and intestinal microbiota in the stool samples was analyzed using 16S metagenome sequencing. TIICs subpopulations in the normal mucosa and tumor samples were evaluated, and the correlations between the TIIC subpopulations and intestinal microbiota were analyzed. RESULTS: FOXp3lowCD45RA+ Tregs were significantly reduced (p = 0.02), FOXp3lowCD45RA- Tregs were significantly increased (p = 0.006), and M1 TAMs were significantly reduced in the tumor samples (p = 0.03). Bacteroides (phylum Bacteroidetes) and Faecalibacterium (phylum Firmicutes) were increased in the patients with high numbers of Tregs and clearly high distribution of FOXp3highCD45RA- Tregs, which are the effector Tregs. Faecalibacterium, Ruminococcaceae, Eubacterium (phylum Firmicutes), and Bacteroides were increased in patients with a high distribution of M1 TAMs. CONCLUSIONS: The findings of the present study indicate that immune responses to tumors are suppressed in the tumor microenvironment of CRC depending on the increment of Tregs and the reduction of M1 TAMs and that intestinal microbiota might be involved in immunosuppression.

[Regulation of PD-L1 by MicroRNA in Mismatch Repair Deficient-Colorectal Cancer].

Programmed cell death 1(PD-1)/PD-ligand 1(PD-L1)immune checkpoint blockade has emerged as a promising therapeutic strategy in various types of cancer. In a recent phase II clinical trial, treatment with the anti-PD-1 agent, pembrolizumab, resulted in considerable clinical benefit in patients with mismatch repair(MMR)-deficient colorectal cancer(CRC). Upregulation of PD-1on T-cells and PD-L1 on tumor cells induces inhibitory signals to suppress T-cell activation, leading to an immune-suppressive microenvironment particularly in MMR-deficient tumors. However, the regulation of PD-L1 expression on CRC cells is poorly understood. We hypothesized that certain microRNAs(miRNAs)are involved in the immunosuppressive microenvironment by directly targeting PD-L1. We identified candidate miRNAs by RNA-sequence analyses for mRNA and miRNA expression obtained from the TCGA colon adenocarcinoma database combined with miRNA target prediction programs. We found that forced miRNA expression could decrease PD-L1 expression on cancer cell lines. Our findings may facilitate an understanding of the role of miRNAs in PD-L1 regulation and also suggest potential miRNAs to serve as biomarkers and therapeutic targets for cancer immunotherapy.

Tumor Infiltrating Effector Regulatory T Cells Express VEGF Receptor 2 in Patients With Colorectal Cancer.

BACKGROUND/AIM: Regulatory T cells (Tregs) suppress various anti-tumor immune responses in the tumor microenvironment (TME) and their control is considered essential to enhancing efficacy of cancer immunotherapy. The purpose of the study was to evaluate the strategy to regulate Tregs through the vascular endothelial growth factor (VEGF) pathway. MATERIALS AND METHODS: We evaluated VEGF receptor (VEGFR) expression in subtypes of Tregs by analysis of public databases and through flow cytometry by investigating surgically resected specimens and peripheral blood mononuclear cells (PBMCs) from 26 patients with advanced colorectal cancer (CRC). RESULTS: Analysis of The Cancer Genome Atlas colorectal adenocarcinoma dataset (n=592) showed that mRNA expression of both FLT1 (VEGFR1) and KDR (VEGFR2) was positively correlated with mRNA expression of FOXP3 as well as Treg signature. Clinical specimens revealed abundant VEGFR2 expression on Tregs, but very marginal VEGFR1 expression. The frequency of effector Tregs, the most immunosuppressive fraction of Tregs, was significantly higher in the tumor than in the PBMC and normal mucosa, and the majority of effector Tregs expressed VEGFR2. Furthermore, by using in vitro generated Tregs, the proportion of Tregs expressing IL-10 or TGF-ß1 was significantly inhibited by a VEGFR2 inhibitor. CONCLUSION: A therapeutic strategy targeting the VEGFR2 axis may have a potential to control effector Tregs in the CRC-TME.

Prognostic role of ARID1A negative expression in gastric cancer.

AT-rich interactive domain 1A (ARID1A) functions as a tumor suppressor and several therapeutic targets in ARID1A-mutated cancers are under development. Here, we investigated the prognostic value of ARID1A for gastric cancer and its association with expression of PD-L1 and p53. ARID1A expression was examined by immunohistochemistry and negative expression of ARID1A was detected in 39 (19.5%) of 200 cases in a test cohort and in 40 (18.2%) of 220 cases in a validation cohort. Negative expression of ARID1A was associated with worse overall survival in undifferentiated cases, particularly early-stage cases. Negative expression of ARID1A was detected in 11 (50%) of 22 PD-L1-positive cases and in 68 (17.1%) of 398 PD-L1-negative cases in a combined cohort. Negative expression of ARID1A was detected in 45 (22%) of 205 p53-positive cases and in 34 (15.8%) of 215 p53-negative cases in a combined cohort. In addition, expression of EZH2, a potential synthetic lethal target in ARID1A-mutated tumors, was detected in 79 ARID1A-negative cases. An ARID1A-knockdown gastric cancer cell line was subjected to microarray analysis, but no actionable targets or pathways were identified. The present results indicate that ARID1A may serve as an early-stage prognostic biomarker for undifferentiated gastric cancer.

miRNA-148a-3p Regulates Immunosuppression in DNA Mismatch Repair-Deficient Colorectal Cancer by Targeting PD-L1.

Immunotherapy against the interaction between programmed cell death 1/programmed cell death ligand 1 (PD-L1) has emerged as a promising strategy for colorectal cancer with mismatch repair deficiency (dMMR) or microsatellite instability-high (MSI-H). The study aimed to identify miRNAs that posttranscriptionally control PD-L1 expression on tumor cells and also regulate immune evasion. A comprehensive miRNA screening using The Cancer Genome Atlas (TCGA) dataset (n = 260) combined with eight different miRNA target prediction programs resulted in the identification of a tumor suppressive miRNA, miR-148a-3p, as a potential negative regulator of PD-L1 expression, particularly in dMMR/MSI-H colorectal cancer. Using multiple cohorts of colorectal cancer, including TCGA data, a microarray dataset (n = 148), and formalin-fixed, paraffin-embedded samples (n = 395), we found that the expression of miR-148a-3p was decreased in dMMR/MSI-H tumors, correlating inversely with PD-L1 levels. We demonstrate that miR-148a-3p directly binds to the 3'-untranslated region of PD-L1, thereby reducing whole-cell and cell surface PD-L1 levels in HCT116 and SW837 cell lines. Overexpression of miR-148a-3p repressed IFNγ-induced PD-L1 expression on tumor cells and consequently diminished T-cell apoptosis in a coculture model of IL2-activated T cells and IFNγ-treated tumor cells. In conclusion, our data support a regulatory mechanism of PD-L1 expression on tumor cells and immune suppression via miR-148a-3p downregulation in colorectal cancer. IMPLICATIONS: This study provides novel evidence that miR-148a-3p negatively regulates tumor cell PD-L1 expression and decreased levels of miR-148a-3p contributes to the immunosuppressive tumor microenvironment.

Augmentation of antibody-dependent cellular cytotoxicity with defucosylated monoclonal antibodies in patients with GI-tract cancer.

Enhancement of antibody-dependent cellular cytotoxicity (ADCC) with some modalities may be a promising approach to enhance the efficacy of therapeutic monoclonal antibodies (mAbs). It has previously been demonstrated that the removal of fucose from antibody oligosaccharides (defucosylation) leads to augmentation of ADCC activity. To establish clinically relevant evidence of this procedure, the present study evaluated trastuzumab- and cetuximab-mediated ADCC by comparing defucosylated mAbs with conventional mAbs using peripheral blood mononuclear cells (PBMCs). PBMCs were isolated from 20 patients with gastrointestinal tract cancer and 10 healthy volunteers. ADCCs were measured using PBMCs as effector cells and two gastric cancer cell lines as target cells. ADCCs were significantly enhanced with defucosylated mAbs compared with conventional mAbs using PBMC from the healthy donors and patients with cancer. The results confirmed that the cetuximab- and trastuzumab-mediated ADCCs in advanced disease were impaired in comparison to those in early disease or healthy individuals. However, when the defucosylated mAbs were used instead of the conventional mAbs, the ADCC activities in the advanced cases were almost comparable with those in early disease or healthy individuals. Furthermore, the expression of ADCC associated molecules were modified toward immunosuppressive status with a mitogen-activated protein kinase inhibitor in vitro, the conventional cetuximab- and trastuzumab-mediated ADCC was downregulated, and the defucosylated mAbs overcome the downregulation of ADCC. In conclusion, defucosylated therapeutic mAbs may enhance ADCC activities in patients with cancer, which may lead to more effective anti-cancer treatments.

Glycosyltransferase Gene Expression Identifies a Poor Prognostic Colorectal Cancer Subtype Associated with Mismatch Repair Deficiency and Incomplete Glycan Synthesis.

Purpose: We aimed to discover glycosyltransferase gene (glycogene)-derived molecular subtypes of colorectal cancer associated with patient outcomes.Experimental Design: Transcriptomic and epigenomic datasets of nontumor, precancerous, cancerous tissues, and cell lines with somatic mutations, mismatch repair status, clinicopathologic and survival information were assembled (n = 4,223) and glycogene profiles were analyzed. IHC for a glycogene, GALNT6, was conducted in adenoma and carcinoma specimens (n = 403). The functional role and cell surface glycan profiles were further investigated by in vitro loss-of-function assays and lectin microarray analysis.Results: We initially developed and validated a 15-glycogene signature that can identify a poor-prognostic subtype, which closely related to deficient mismatch repair (dMMR) and GALNT6 downregulation. The association of decreased GALNT6 with dMMR was confirmed in multiple datasets of tumors and cell lines, and was further recapitulated by IHC, where approximately 15% tumors exhibited loss of GALNT6 protein. GALNT6 mRNA and protein was expressed in premalignant/preinvasive lesions but was subsequently downregulated in a subset of carcinomas, possibly through epigenetic silencing. Decreased GALNT6 was independently associated with poor prognosis in the IHC cohort and an additional microarray meta-cohort, by multivariate analyses, and its discriminative power of survival was particularly remarkable in stage III patients. GALNT6 silencing in SW480 cells promoted invasion, migration, chemoresistance, and increased cell surface expression of a cancer-associated truncated O-glycan, Tn-antigen.Conclusions: The 15-glycogene signature and the expression levels of GALNT6 mRNA and protein each serve as a novel prognostic biomarker, highlighting the role of dysregulated glycogenes in cancer-associated glycan synthesis and poor prognosis. Clin Cancer Res; 24(18); 4468-81. ©2018 AACR.

Prognostic role of FUT8 expression in relation to p53 status in stage II and III colorectal cancer.

The expression of fucosyltransferase 8, an enzyme responsible for core fucosylation encoded by FUT8, influences tumor biology and correlates with patient prognosis in several solid cancers. We hypothesized that p53 alteration modifies prognostic associations of FUT8 expression in colorectal cancer (CRC), since FUT8 has recently been identified as a direct transcriptional target of wild-type p53. Utilizing multiple datasets of microarray and RNA sequence of CRC, FUT8 mRNA was found to be highly expressed in wild-type p53 tumors (n = 382) compared to those of mutant p53 (n = 437). Prognostic values of FUT8 expression in conjunction with the p53 status for disease-free survival (DFS) were analyzed using two independent cohorts of stage II and III CRC after curative surgery, including the immunohistochemistry (IHC) cohort (n = 123) and the microarray cohort (n = 357). In both cohorts, neither FUT8 expression nor the p53 status was associated with DFS. Strikingly, positive expression of FUT8 protein was significantly associated with better DFS only in tumors with negative p53, while it had no prognostic impact in tumors with positive p53 in the IHC cohort. Although not statistically significant, a similar prognostic trend was observed in the microarray cohort when patients were stratified by the p53 status. Our results suggest that the prognostic values of FUT8 expression on DFS may be modified by the p53 status, and the expression of FUT8 protein can be a prognostic biomarker for patients with stage II and III CRC.

Epithelial-mesenchymal transition-converted tumor cells can induce T-cell apoptosis through upregulation of programmed death ligand 1 expression in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is an aggressive tumor, and it is urgently needed to develop novel therapeutic strategies including immunotherapy. In this study, we investigated the upregulation of the programmed death ligand 1 (PD-L1) due to epithelial-mesenchymal transition (EMT) in ESCC using an in vitro treatment system with the EMT inducer, glycogen synthase kinase (GSK)-3 inhibitor, and we also analyzed the correlation of EMT and PD-L1 expression in the clinical tumor samples of both tissue microarray (TMA) samples (n = 177) and whole tissue samples (n = 21). As a result, the inhibition of GSK-3ß induces EMT phenotype with upregulated vimentin and downregulated E-cadherin as well as increased Snail and Zinc finger E box-binding homeobox (ZEB)-1 gene expression. Simultaneously, we showed that EMT-converted ESCC indicated the upregulation of PD-L1 at both protein (total and surface) and mRNA levels. Of importance, we showed that EMT-converted tumor cells have a capability to induce T-cell apoptosis to a greater extent in comparison to original epithelial type tumor cells. Furthermore, the immunohistochemical stains of ESCC showed that PD-L1 expression on tumor cells was positively correlated with EMT status in TMA samples (P = .0004) and whole tissue samples (P = .0029). In conclusion, our in vitro and in vivo study clearly demonstrated that PD-L1 expression was upregulated in mesenchymal type tumors of ESCC. These findings provide a strong rationale for the clinical use of anti-PD-1/anti-PD-L1 monoclonal antibodies for advanced ESCC patients.

Identification of Three Novel Fusion Oncogenes, SQSTM1/NTRK3, AFAP1L2/RET, and PPFIBP2/RET, in Thyroid Cancers of Young Patients in Fukushima.

BACKGROUND: The BRAFV600E mutation is the most frequent genetic abnormality in adult papillary thyroid carcinomas (PTCs). On the other hand, various chromosomal rearrangements are more prevalent in childhood and adolescent PTCs. The aim of the present study was to identify novel rearrangements in PTCs from young patients. METHODS: Among 63 postoperative specimens of childhood and adolescent PTCs, which had been discovered by the thyroid ultrasound screening program in Fukushima, nine samples without prevalent known oncogenes, BRAFV600E, RAS, RET/PTC1, RET/PTC3, and ETV6/NTRK3, were analyzed in the current study by quantitative real-time reverse transcription polymerase chain reaction to screen for novel fusion genes by comparing transcript expression between extracellular and kinase domains of ALK, NTRK1, NTRK3, and RET. RESULTS: Of the above nine samples, five samples were suspected to harbor a fusion, and using subsequent 5' rapid amplification of cDNA end (RACE), two already reported fusion oncogenes, STRN/ALK and TPR/NTRK1, and three novel fusions, SQSTM1/NTRK3, AFAP1L2/RET, and PPFIBP2/RET, were identified. Functional analyses of these three chimeric genes were performed, and their transforming abilities were confirmed through the activation of mitogen-activated protein kinase (MAPK). CONCLUSIONS: Three novel fusion oncogenes have been identified in young PTC patients in Fukushima, suggesting that rare fusions may be present among the cases negative for known oncogenes in this age group and that such rearrangements can play a significant role in thyroid carcinogenesis.

Immunosuppression involving increased myeloid-derived suppressor cell levels, systemic inflammation and hypoalbuminemia are present in patients with anaplastic thyroid cancer.

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive neoplasms in humans and myeloid-derived suppressor cells (MDSCs) contribute to the negative regulation of immune responses in the context of cancer and inflammation. In order to investigate the pathophysiology of thyroid cancer, peripheral blood mononuclear cells (PBMCs) were obtained from 49 patients with thyroid cancer, 18 patients with non-cancerous thyroid diseases and 22 healthy volunteers. The MDSC levels were found to be higher in patients with any type of thyroid cancer (P<0.05), patients with ATC (P<0.001) and patients with medullary thyroid carcinoma (P<0.05), when compared to patients with non-cancerous thyroid diseases. The MDSC levels were also higher in patients with stage III-IV thyroid cancer compared to those in patients with non-cancerous thyroid diseases (P<0.05). The stimulation index (SI) of phytohemagglutinin (PHA)-induced lymphocyte blastogenesis was significantly lower, the C-reactive protein (CRP) levels were significantly higher and the serum albumin levels were significantly lower in patients with ATC compared to those in patients with non-cancerous thyroid diseases. The SI was significantly lower in stage III and IV thyroid cancer compared to that in non-cancerous thyroid disease (P<0.05). Furthermore, the CRP levels were higher and the concentration of albumin was lower in stage IV thyroid cancer compared to those in non-cancerous thyroid disease (P<0.05). Patients with thyroid carcinoma were then classified into one of two groups according to a %PBMC of MDSC cut-off level of 1.578, which was the average %PBMC of MDSC of patients with any type of thyroid carcinoma. In patients with higher MDSC levels, the production of CRP and interleukin (IL)-10 was significantly higher (P<0.05) and the albumin levels were significantly lower (P<0.05) compared to those in patients with lower MDSC levels. These data indicate that MDSCs are increased in patients with ATC. Furthermore, these patients exhibited suppression of cell-mediated immune responses, chronic inflammation and nutritional impairment.