RHAMM marks proliferative subpopulation of human colorectal cancer stem cells.

The cancer stem cell (CSC) theory features typically rare self-renewing subpopulations that reconstitute the heterogeneous tumor. Identification of molecules that characterize the features of CSCs is a key imperative for further understanding tumor heterogeneity and for the development of novel therapeutic strategies. However, the use of conventional markers of CSCs is still insufficient for the isolation of bona fide CSCs. We investigated organoids that are miniature forms of tumor tissues by reconstructing cellular diversity to identify specific markers to characterize CSCs in heterogeneous tumors. Here, we report that the receptor for hyaluronan-mediated motility (RHAMM) expresses in a subpopulation of CD44+ conventional human colorectal CSC fraction. Single-cell transcriptomics of organoids highlighted RHAMM-positive proliferative cells that revealed distinct characteristics among the various cell types. Prospectively isolated RHAMM+CD44+ cells from the human colorectal cancer tissues showed highly proliferative characteristics with a self-renewal ability in comparison with the other cancer cells. Furthermore, inhibition of RHAMM strongly suppressed organoid formation in vitro and inhibited tumor growth in vivo. Our findings suggest that RHAMM is a potential therapeutic target because it is a specific marker of the proliferative subpopulation within the conventional CSC fraction.

Survival outcomes including salvage therapy of adult head and neck para-meningeal rhabdomyosarcoma: a multicenter retrospective study from Japan.

BACKGROUND: Rhabdomyosarcoma is the most common soft tissue sarcoma in children, but rare in adults. Para-meningeal rhabdomyosarcoma in head and neck (PM-HNRMS) is less applicable for surgery due to the anatomic reason. PM-HNRMS has a poor prognosis in children. However, its clinical outcomes remain unclear in adults due to the rarity. Further, there is almost no detailed data about salvage therapy. METHODS: We retrospectively examined the adult patients with PM-HNRMS treated at institutions belonging to the Kyushu Medical Oncology Group from 2009 to 2022. We evaluated the overall survival (OS) and progression-free survival (PFS) of the patients who received a first-line therapy. We also reviewed the clinical outcomes of patients who progressed against a first-line therapy and received salvage therapy. RESULTS: Total 11 patients of PM-HNRMS received a first-line therapy. The characteristics were as follows: median age: 38 years (range 25 - 63 years), histology (alveolar/spindle): 10/1, and risk group (intermediate/high): 7/4. As a first-line therapy, VAC and ARST0431-based regimen was performed in 10 and 1 patients, respectively. During a first-line therapy, definitive radiation for all lesions were performed in seven patients. The median PFS was 14.2 months (95%CI: 6.0 - 25.8 months): 17.1 months (95%CI: 6.0 - not reached (NR)) for patients with stage I-III and 8.5 months (95%CI: 5.2 - 25.8 months) for patients with stage IV. The 1-year and 3-year PFS rates were 54.5% and 11.3% for all patients. Median OS in all patients was 40.8 months (95%CI: 12.1 months-NR): 40.8 months (95%CI: 12.1 - NR) for patients with stage I-III and NR for patients with stage IV. The 5-year OS rate was 48.5% for all patients. Among seven patients who received salvage therapy, three are still alive, two of whom remain disease-free for over 4 years after completion of the last therapy. Those two patients received multi-modal therapy including local therapy for all detected lesions. CONCLUSION: The cure rate of adult PM-HNRMS is low in spite of a first-line therapy in this study. Salvage therapy might prolong the survival in patients who received the multi-modal therapy including local therapy for all detected lesions.

Organoid Models of Tumor Immunology.

Cellular interactions in the tumor microenvironment (TME) significantly govern cancer progression and drug response. The efficacy of clinical immunotherapies has fostered an exponential interest in the tumor immune microenvironment, which in turn has engendered a pressing need for robust experimental systems modeling patient-specific tumor-immune interactions. Traditional 2D in vitro tumor immunotherapy models have reconstituted immortalized cancer cell lines with immune components, often from peripheral blood. However, newly developed 3D in vitro organoid culture methods now allow the routine culture of primary human tumor biopsies and increasingly incorporate immune components. Here, we present a viewpoint on recent advances, and propose translational applications of tumor organoids for immuno-oncology research, immunotherapy modeling, and precision medicine.

A human SIRPA knock-in xenograft mouse model to study human hematopoietic and cancer stem cells.

In human-to-mouse xenogeneic transplantation, polymorphisms of signal-regulatory protein α (SIRPA) that decide their binding affinity for human CD47 are critical for engraftment efficiency of human cells. In this study, we generated a new C57BL/6.Rag2nullIl2rgnull (BRG) mouse line with Sirpahuman/human (BRGShuman) mice, in which mouse Sirpa was replaced by human SIRPA encompassing all 8 exons. Macrophages from C57BL/6 mice harboring Sirpahuman/human had a significantly stronger affinity for human CD47 than those harboring SirpaNOD/NOD and did not show detectable phagocytosis against human hematopoietic stem cells. In turn, Sirpahuman/human macrophages had a moderate affinity for mouse CD47, and BRGShuman mice did not exhibit the blood cytopenia that was seen in Sirpa-/- mice. In human to mouse xenograft experiments, BRGShuman mice showed significantly greater engraftment and maintenance of human hematopoiesis with a high level of myeloid reconstitution, as well as improved reconstitution in peripheral tissues, compared with BRG mice harboring SirpaNOD/NOD (BRGSNOD). BRGShuman mice also showed significantly enhanced engraftment and growth of acute myeloid leukemia and subcutaneously transplanted human colon cancer cells compared with BRGSNOD mice. BRGShuman mice should be a useful basic line for establishing a more authentic xenotransplantation model to study normal and malignant human stem cells.

Potential therapeutic targets discovery by transcriptome analysis of an in vitro human gastric signet ring carcinoma model.

BACKGROUND: Loss of E-cadherin expression is frequently observed in signet ring carcinoma (SRCC). People with germline mutations in CDH1, which encodes E-cadherin, develop diffuse gastric cancer at a higher rate. Loss of E-cadherin expression is thus assumed to trigger oncogenic development. METHODS: To investigate novel therapeutic targets for gastric SRCC, we engineered an E-cadherin-deficient SRCC model in vitro using a human gastric organoid (hGO) with CDH1 knockout (KO). RESULTS: CDH1 KO hGO cells demonstrated distinctive morphological changes similar to SRCC and high cell motility. RNA-sequencing revealed up-regulation of matrix metalloproteinase (MMP) genes in CDH1 KO hGO cells compared to wild type. MMP inhibitors suppressed cell motility of CDH1 KO hGO cells and SRCC cell lines in vitro. Immunofluorescent analysis with 95 clinical gastric cancer tissues revealed that MMP-3 was specifically abundant in E-cadherin-aberrant SRCC. In addition, CXCR4 molecules translocated onto the cell membrane after CDH1 KO. Addition of CXCL12, a ligand of CXCR4, to the culture medium prolonged cell survival of CDH1 KO hGO cells and was abolished by the inhibitor, AMD3100. In clinical SRCC samples, CXCL12-secreting fibroblasts showed marked infiltration into the cancer area. CONCLUSIONS: E-cadherin deficient SRCCs might gain cell motility through upregulation of MMPs. CXCL12-positive cancer-associated fibroblasts could serve to maintain cancer-cell survival as a niche. MMPs and the CXCL12/CXCR4 axis represent promising candidates as novel therapeutic targets for E-cadherin-deficient SRCC.

Hypoalbuminemia for the prediction of venous thromboembolism and treatment of direct oral anticoagulants in metastatic gastric cancer patients.

BACKGROUND: Venous thromboembolism (VTE) is highly associated with advanced gastric cancer (AGC) and is sometimes lethal. Predictors of VTE have not been identified, and the efficacy and safety of direct oral anticoagulants (DOACs) for AGC-associated VTE remain to be clarified. METHODS: A total of 188 AGC patients who started chemotherapy during the period from January 2014 to December 2017 in our institutions were retrospectively examined for the incidence of VTE, risk factors for VTE, and the efficacy and safety of DOAC-based anticoagulant therapy for VTE. RESULTS: Thirty-four patients (18%) were diagnosed with VTE at the start or during the course of chemotherapy (VTE group). More VTE group patients had a history of abdominal surgery and had moderate-severe ascites (32% versus 17%, 32% versus 14%, respectively) than non-VTE group patients (NVTE group). The mean serum albumin concentrations in the VTE group were significantly lower than NVTE group (3.38 mg/dL vs 3.65 mg/dL, respectively). Multivariate analysis showed that hypoalbuminemia was significantly correlated with VTE (P = 0.012). In the VTE group, 29 patients (85%) received anticoagulant therapy, including 24 patients treated with DOACs. No lethal VTE was observed in any patients. Thirteen patients (45%) terminated DOACs because of anemia or bleeding events, of whom eleven developed major bleeding. Median overall survivals of the VTE and NVTE groups were 9.63 months and 11.5 months, respectively (P = 0.262). CONCLUSION: Hypoalbuminemia appears to be a risk factor for AGC-associated VTE. DOACs are effective to AGC-associated VTE, but careful observation of bleeding events is required.

PD-1+ TIM-3+ T cells in malignant ascites predict prognosis of gastrointestinal cancer.

The liquid biopsy of ascites fluid could be an excellent source of tumor and microenvironment for the study of prognostic biomarkers because of its accessibility. Tumor-infiltrating lymphocytes (TILs) can predict prognosis in multiple malignancies, including the response to immune checkpoint inhibitors, a breakthrough cancer therapy. However, TILs' profiles from malignant ascites have not been extensively studied. Using flow cytometric analysis, we quantified the proportion of exhausted T cells and memory/naive/effector T-cell subsets, among the CD4+ and CD8+ T-cell populations of paired TILs and peripheral blood T cell samples (n = 22). The correlation between CD4+ and CD8+ subset profiles suggested that the combined analysis of CD4+ and CD8+ cells in malignant ascites was clinically significant. We found that cells positive for the exhaustion markers programmed cell death-1 (PD-1), and T-cell immunoglobulin and mucin domain 3 (TIM-3), and cells coexpressing PD-1 and TIM-3 abundantly exist among malignant ascites TILs. Furthermore, patients with high frequency of PD-1+ TIM-3+ cells among the CD4+ and CD8+ T-cell population showed worse clinical outcome in multivariate analysis (n = 27). We propose that exhausted ascites TILs represent a clinically significant prognostic biomarker in advanced gastrointestinal cancer and represent an important target for immune checkpoint inhibitors.

Activation of central/effector memory T cells and T-helper 1 polarization in malignant melanoma patients treated with anti-programmed death-1 antibody.

Human anti-programmed death-1 (PD-1) antibody possesses the capability to revitalize host T cells and has been an effective therapy for metastatic malignant melanoma (MM). The precise subsets of T cells predominantly activated by anti-PD-1, however, have not yet been clarified. In this study, peripheral blood mononuclear cells obtained from MM patients scheduled to receive anti-PD-1 (nivolumab) therapy, and healthy subjects (HS), were systematically examined on flow cytometry to identify changes in the proportion of immune cell subsets. Compared with HS, MM patients prior to therapy had an increased proportion of activated CD8+ T cells with effector memory phenotypes (Tem), and PD-1 positive subsets of CD4+ central memory T cells (Tcm) and T-helper (Th)17 cells. After a single course of anti-PD-1 therapy, MM patients had an increase in activated Tem and Tcm subsets of CD4+ and CD8+ T cells, and activated Th1 plus T-helper follicular 1 cells. There was no consistent change in the proportion of Tfh cells, B cells, natural killer cells, or dendritic cells. The observed activated phenotypes were attenuated during the course of therapy, but regulatory T cells belonging to the CD3+CD4+CD45RO+CD25high fraction increased at disease progression. Taken together, anti-PD-1 therapy modulates systemic immune reactions and exerts anti-tumor effects, not only by revitalizing Tem and Tcm of CD4+ and CD8+ T cells, but also via a shift to a Th1 phenotype.

Epithelial-mesenchymal transition is activated in CD44-positive malignant ascites tumor cells of gastrointestinal cancer.

Disseminated cancer cells in malignant ascites possess unique properties that differ from primary tumors. However, the biological features of ascites tumor cells (ATC) have not been fully investigated. By analyzing ascites fluid from 65 gastrointestinal cancer patients, the distinguishing characteristics of ATC were identified. High frequency of CD44+ cells was observed in ATC using flow cytometry (n = 48). Multiplex quantitative PCR (n = 15) showed higher gene expression of epithelial-mesenchymal transition (EMT)-related genes and transforming growth factor beta (TGF-beta)-related genes in ATC than in the primary tissues. Immunohistochemistry (n = 10) showed that ATC also had much higher expression of phosphorylated SMAD2 than that in the corresponding primary tissues. TGF-beta 1 was detected in all cases of malignant ascites by enzyme-linked immunoassay (n = 38), suggesting the possible interaction of ATC and the ascites microenvironment. In vitro experiments revealed that these ATC properties were maintained by TGF-beta 1 in cultured ATC(n = 3). Here, we showed that ATCrevealed high frequencies of CD44 and possessed distinct EMT features from primary tissues that were mainly maintained by TGF-beta 1 in the ascites.

Retrospective analysis of cardiovascular diseases related to chemotherapies for advanced solid tumor patients.

Appropriate management of cardiovascular diseases (CVDs) related to chemotherapy for solid tumors is important for safe oncologic treatment. However, prediction of the onset and progression of CVDs has not generally been established in Japan. We carried out a retrospective analysis of advanced or recurrent solid tumor patients who received chemotherapies in a single institution. Patient characteristics, chemotherapy regimens, adverse events, CVDs before chemotherapy, and diagnosis of CVDs in association with chemotherapy were assessed. During the period from April 2006 to March 2012, 394 patients were examined. Cardiac diseases (CDs), hypertension (HT), or arterial thrombosis or venous thromboembolism were prevalent in 37 (9.4%), 22 (5.6%), five (1.3%), and 14 (3.5%) cases, respectively. HT (14.5%) and venous thrombosis (5.8%) were frequent in patients who received bevacizumab-containing chemotherapy. Four cases with left ventricular dysfunction experienced a decrease of ejection fraction and early filling/atrial filling (E/A) and E/A tended to decrease before ejection fraction. Ninety (62.1%) of 145 cases showed an increase in the D-dimer (DD) level before chemotherapy, and a further increase in DD level was found when venous thrombosis occurred. Relative risks of the disease progression of HT, CD, and thromboembolism because of chemotherapy were 1.3, 1.9, and 3.6, respectively. A decrease in E/A and an increase in DD were suggested to be valuable for early diagnosis of the respective onsets of left ventricular dysfunction and venous thrombosis related to chemotherapy. We conclude that patients with previous CD tend to have disease progression of CD during chemotherapy.

Efficacy and safety analysis of chemotherapy for advanced colitis-associated colorectal cancer in Japan.

Chemotherapy for advanced colitis-associated colorectal cancer (CAC) has been insufficiently evaluated. The goal of this study was to clarify the efficacy and safety of chemotherapy for CAC in Japan. CAC patients who were treated with chemotherapy between 2005 and 2015 were retrospectively examined. Twenty-nine patients (median age, 48 years; 23 men) were assessed. Eighteen patients had ulcerative colitis, and 11 had Crohn's disease. Three ulcerative colitis and four Crohn's disease patients were in the active disease phase. Primary tumors were located in the rectum/anus (n=16), the left colon (n=9), or the right colon (n=4). Palliative or adjuvant chemotherapy was performed in 13 and 16 patients, respectively. First-line palliative chemotherapy regimens were as follows: fluorouracil, leucovorin, and oxaliplatin (FOLFOX; n=6), FOLFOX+bevacizumab (n=3), and others (n=4). Adjuvant chemotherapy regimens were S-1 (n=7), oxaliplatin-based (n=4) and others (n=5). In palliative chemotherapy, the objective response rate was 15%, and the median progression-free survival and overall survival were 182 and 315 days, respectively. In adjuvant chemotherapy, the 5-year relapse-free survival rate was 78%. Grade 3/4 adverse events (AEs) were observed in 16 patients (55%). Active and remission inflammatory bowel disease patients suffered grade 3/4 nonhematological AEs at an incidence of 71 and 23%, respectively (P<0.01). Dose reduction was required in 11 patients (38%), eight of whom required it for hematological AEs. Adjuvant chemotherapy for CAC exhibited sufficient efficacy, whereas modest efficacy was shown for palliative chemotherapy for CAC. AEs, particularly nonhematological AEs, were closely associated with disease activity of colitis.

Albumin-Bilirubin Grade Analyses of Atezolizumab plus Bevacizumab versus Sorafenib in Patients with Unresectable Hepatocellular Carcinoma: A Post Hoc Analysis of the Phase III IMbrave150 Study.

Introduction: Atezolizumab + bevacizumab showed survival benefit in patients with unresectable hepatocellular carcinoma (HCC) versus sorafenib in the Phase III IMbrave150 study. This exploratory analysis examined the prognostic impact of a baseline albumin-bilirubin (ALBI) score. Methods: Patients with treatment-naïve unresectable HCC, ≥1 measurable untreated lesion, and Child-Pugh class A liver function were randomized 2:1 to receive atezolizumab 1,200 mg + bevacizumab 15 mg/kg every 3 weeks or sorafenib 400 mg twice daily. Overall survival (OS) and progression-free survival (PFS) were assessed in the intention-to-treat population by ALBI/modified (m)ALBI grade. Time to deterioration (TTD; defined as time to 0.5-point increase from the baseline ALBI score over 2 visits or death) of liver function and safety were investigated. Results: Of 501 enrolled patients, 336 were randomized to receive atezolizumab + bevacizumab (ALBI grade [G] 1: n = 191; G2: n = 144 [mALBI G2a: n = 72, G2b: n = 72]; missing ALBI grade: n = 1) and 165 to sorafenib (ALBI G1: n = 87; G2: n = 78 [mALBI G2a: n = 37; G2b: n = 41]). Median follow-up was 15.6 months. OS and PFS improved with atezolizumab + bevacizumab versus sorafenib in patients with ALBI G1 (OS HR: 0.50 [95% CI: 0.35, 0.72]; PFS HR: 0.61 [95% CI: 0.45, 0.82]). In patients with ALBI G2 or mALBI G2a or G2b, PFS was numerically longer with atezolizumab + bevacizumab versus sorafenib, but no OS benefit was seen. Median TTD in the intention-to-treat population was 10.2 months (95% CI: 8.0, 11.0) with atezolizumab + bevacizumab versus 8.6 months (95% CI: 6.2, 11.8) with sorafenib (HR: 0.82 [95% CI: 0.65, 1.03]). Safety profiles of atezolizumab and bevacizumab were consistent with previous analyses, regardless of ALBI grade. Conclusion: ALBI grade appeared to be prognostic for outcomes with both atezolizumab + bevacizumab and sorafenib treatment in patients with HCC. Atezolizumab + bevacizumab preserved liver function for a numerically longer duration than sorafenib.

Immune organoids: from tumor modeling to precision oncology.

Cancer immunotherapies, particularly immune checkpoint inhibitors, are rapidly becoming standard-of-care for many cancers. The ascendance of immune checkpoint inhibitor treatment and limitations in the accurate prediction of clinical response thereof have provided significant impetus to develop preclinical models that can guide therapeutic intervention. Traditional organoid culture methods that exclusively grow tumor epithelium as patient-derived organoids are under investigation as a personalized platform for drug discovery and for predicting clinical efficacy of chemotherapies and targeted agents. Recently, the patient-derived tumor organoid platform has evolved to contain more complex stromal and immune compartments needed to assess immunotherapeutic efficacy. We review the different methodologies for developing a more holistic patient-derived tumor organoid platform and for modeling the native immune tumor microenvironment.

Macrophages are primed to transdifferentiate into fibroblasts in malignant ascites and pleural effusions.

Cancer-associated fibroblasts (CAFs) play an important role in cancer progression. However, the origin of CAFs remains unclear. This study shows that macrophages in malignant ascites and pleural effusions (cavity fluid-associated macrophages: CAMs) transdifferentiate into fibroblast-like cells. CAMs obtained from gastrointestinal cancer patients were sorted by flow cytometry and cultured in vitro. CD45+CD14+ CAMs transdifferentiated into CD45-CD90+ fibroblast-like cells that exhibited spindle shapes. Then, cDNA microarray analysis showed that the CD45-CD90+ fibroblast-like cells (macrophage-derived CAFs: MDCAFs) had a fibroblast-specific gene expression signature and produced growth factors for epithelial cell proliferation. Human colon cancer cells transplanted into immunodeficient mice with MDCAFs formed larger tumors than cancer cells alone. Gene ontology analyses showed the involvement of TGFß signaling and cell-matrix adhesion in MDCAFs, and transdifferentiation of CAMs into MDCAFs was canceled by inhibiting TGFß and cell adhesion. Furthermore, the acquired genetic alterations in hematopoietic stem cells (HSCs) were shared in CAMs and MDCAFs. Taken together, CAMs could be a source of CAFs and might originate from HSCs. We propose the transdifferentiation process of CAMs into MDCAFs as a new therapeutic target for fibrosis associated with gastrointestinal cancer.

Spontaneous Regression of Metachronous Intra-Abdominal Desmoid Tumor in a Patient with Familial Adenomatous Polyposis.

Desmoid tumors are clonal fibroblastic neoplasms that arise in soft tissues. Patients with familial adenomatous polyposis (FAP) can develop intra-abdominal desmoid tumors. However, metachronous appearance of intra-abdominal desmoid tumor is rare, and its clinical course is not well known. Here, we report a case of spontaneous regression of metachronous intra-abdominal desmoid tumor in a 36-year-old man with FAP. The patient was diagnosed with FAP and underwent laparoscopic total colorectomy. Intra-abdominal desmoid tumor appeared 2 years later and progressed despite treatment with tamoxifen and sulindac. He received four cycles of combinatory therapy with dacarbazine and adriamycin, resulting in shrinkage and stabilization of the desmoid tumor even after cessation of chemotherapy. A new intra-abdominal desmoid tumor developed 2 years later at a different site from the first lesion and progressed from 65 mm to 70 mm in diameter within a month. The size of the first lesion, however, remained unchanged. We prepared for chemotherapy because the second lesion progressed, but follow-up computed tomography showed spontaneous shrinkage of the second lesion. The patient still has not needed additional therapy as of more than 4 years after the appearance of the second lesion. Immunohistochemical staining showed the presence of macrophages in the second lesion. Although metachronous intra-abdominal desmoid tumor is rare and management protocols have yet to be established, this case suggests that an active surveillance approach may be applicable under careful follow-up in asymptomatic patients.

Organoids as Oracles for Precision Medicine in Rectal Cancer.

Two recent papers in Cell Stem Cell and Nature Medicine (Yao et al. [2019] and Ganesh et al. [2019]) demonstrate the successful use of rectal cancer patient-derived organoids to predict patient responses to neoadjuvant chemoradiation therapy, paving the way toward a new paradigm for precision medicine.

Thrombocytopenia Caused by Dexamethasone in a Patient with Colorectal Cancer.

Drug-induced immune thrombocytopenia (DITP) is an important cause of thrombocytopenia. A 73-year-old man with relapsed rectal carcinoma received S-1, oxaliplatin and bevacizumab combination therapy (SOX+Bev). Dexamethasone was administered as an antiemetic prophylaxis. On day 2 of the first cycle, thrombocytopenia (8,000/µL) was observed. We sequentially omitted any drugs suspected to possibly induce thrombocytopenia and confirmed dexamethasone as the cause of thrombocytopenia. DITP induced by synthetic corticosteroids is very rare and this is the first case report of DITP induced by dexamethasone. Although rare, DITP due to synthetic corticosteroids including dexamethasone should be a differential diagnosis among patients receiving synthetic corticosteroids with thrombocytopenia.

Helper T cell-dominant tertiary lymphoid structures are associated with disease relapse of advanced colorectal cancer.

Tertiary lymphoid structures (TLSs), clusters of immune cells found around tumor tissue, have been shown to be associated with anti-tumor immunity, but the cellular composition within each TLS and whether the cellular composition of a TLS affects a patient's prognosis are poorly understood. In the present study, each TLS was categorized according to its cellular composition determined by a system of multiplex immunohistochemical staining and quantitative analysis, and the correlation between the category and prognosis was examined. Sixty-seven patients with curatively resected stage II/III colorectal cancer (CRC) were enrolled. A TLS, consisting of germinal center B cells, follicular dendritic cells, T helper (Th) cells, B cells, cytotoxic T cells, and macrophages, was confirmed in the tumor tissue of 58 patients (87%). The densities of Th cells and macrophages were significantly higher in relapsed patients than in not-relapsed patients (p = .043 and p = .0076). A higher ratio of Th cells was the most significant independent risk factor for disease relapse on multivariate analysis. The subset increasing in Th cells was GATA3+ Th2. A total of 353 TLSs was divided into five clusters according to immune cell composition. Among them, the Th-rich type TLS was significantly increased (p = .0009) in relapsed patients. These data suggest the possibility that Th cell-dominant composition might disturb the anti-tumor immune response, and the function of each TLS might differ depending on its composition.

Methylation of drug resistance-related genes in chemotherapy-sensitive Epstein-Barr virus-associated gastric cancer.

Epstein-Barr virus (EBV)-associated gastric cancer (GC) is associated with a high degree of DNA methylation. However, the association between chemotherapy susceptibility and tumor DNA methylation in advanced diseases remains unclear. The comprehensive DNA methylation status of GC cells obtained from an advanced EBV-associated GC (EBVGC) case, in which complete response to S-1 plus cisplatin chemotherapy was achieved, was analyzed using a DNA methylation microarray. We compared DNA methylation of GC cells with public data and identified genes with higher methylation in EBVGC cell lines than in normal gastric cells, and genes in which methylation was increased by EBV. Of these genes, ABCG2, AHNAK2, BCL2, FZD1, and TP73 are associated with published evidence for resistance to 5-fluorouracil and cisplatin. Silencing of these genes may be associated with hypersensitivity to chemotherapy.

Dedifferentiation process driven by TGF-beta signaling enhances stem cell properties in human colorectal cancer.

Cancer stem cells (CSCs) possess the capacity for self-renewal and the potential to differentiate into non-CSCs. The recent discoveries of dynamic equilibrium between CSCs and non-CSCs revealed the significance of acquiring CSC-like properties in non-CSCs as an important process in progression of cancer. The mechanism underlying acquisition of CSC-like properties has mainly been investigated in the context of epithelial-mesenchymal transition. Here, we demonstrate the dedifferentiation process may be an alternative mechanism in acquisition of CSC-like properties in human colorectal cancer cells. By exploring the single-cell gene expression analysis of organoids developed from CD44+ CSCs, we identified TWIST1 as a key molecule for maintaining the undifferentiated state of cancer cells. Consistent with the finding, we found that TGF-beta signaling pathway, a regulator of TWIST1, was specifically activated in the undifferentiated CD44+ CSCs in human colorectal cancer using microarray-based gene expression analysis and quantitative pathology imaging system. Furthermore, we showed that external stimulation with TGF-beta and the induction of TWIST1 converted CD44- non-CSCs into the undifferentiated CD44+ CSCs, leading to the significant increment of CSCs in xenograft models. This study strongly suggests dedifferentiation driven by TGF-beta signaling enhances stem cell properties in human colorectal cancer.