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Cancer evolution is explained by accumulation of driver mutations and subsequent positive selection by acquired growth advantages like Darwin evolution. However, it has not yet been fully investigated whether negative selection of cells that have lost malignant properties contributes to cancer progression. Using intestinal metastatic tumor-derived organoids carrying Apc, Kras, Tgfbr2, and Trp53 quadruple mutations, we show here that approximately 30% of subclones of the organoids show loss of metastatic ability to the liver, while keeping the driver mutations and oncogenic pathways. Notably, highly metastatic subclones also showed gradual loss of metastatic ability during further passages. Such non-metastatic subclones showed significantly decreased survival and proliferation ability in Matrigel and collagen gel culture conditions, which may cause elimination from the tumor tissues in vivo. RNA sequencing indicated that stemness-related genes including Lgr5 and Myb were significantly downregulated in non-metastatic subclones as well as subclones that lost metastatic ability during additional passages. Furthermore, a CGH analysis showed that non-metastatic subclones were derived from minor population of parental organoid cells. These results indicate that metastatic ability is continuously lost with decreased stem cell property in certain subpopulations of malignant tumors, and such subpopulations are eliminated by negative selection. Therefore, it is possible that cancer evolution is regulated not only by positive selection but by negative selection. The mechanism underlying the loss of metastatic ability will be an important for future development of therapeutic strategies against metastasis.

Supplementary Figure S6. Histopathology analysis of liver cancer.

Suppression of NF-κB and Wnt signaling by Myd88 disruption in BMDCs.

Expression levels of MYD88 and IRF5 in human and mouse gastric cancer.

Expression levels of MyD88-dependent unregulated genes in the gp130F/F mice.

Supplemental Figure S1. Parietal cells loss induced by tamoxifen injection in WT mouse.

Induction of Tlr2 and Cd14 in regenerating gastric mucosa.

Supplementary Materials and Methods.

It has been established that COX-2 and downstream signaling by prostaglandin E2 (PGE2) play a key role in tumorigenesis through generation of inflammatory microenvironment. Toll-like receptor (TLR) signaling through myeloid differentiation factor 88 (MyD88) also regulates inflammatory responses in tumors. However, the relationship between these distinct pathways in tumorigenesis is not yet fully understood. We herein investigated the role of MyD88 in gastric tumorigenesis using Gan mice, which develop inflammation-associated gastric tumors due to the simultaneous activation of the COX-2/PGE2 pathway and Wnt signaling. Notably, the disruption of Myd88 in Gan mice resulted in the significant suppression of gastric tumorigenesis with the inhibition of inflammatory responses, even though COX-2/PGE2 pathway is constitutively activated. Moreover, Myd88 disruption in bone marrow–derived cells (BMDCs) in Gan mice also suppressed inflammation and tumorigenesis, indicating that MyD88 signaling in BMDCs regulates the inflammatory microenvironment. We also found that expression of Tlr2 and its coreceptor Cd14 was induced in tumor epithelial cells in Gan mice, which was suppressed by the disruption of Myd88. It has already been shown that TLR2/CD14 signaling is important for stemness of intestinal epithelial cells. These results indicate that MyD88 in BMDCs, together with COX-2/PGE2 pathway, plays an essential role in the generation of the inflammatory microenvironment, which may promote tumorigenesis through induction of TLR2/CD14 pathway in tumor epithelial cells. These results suggest that inhibition of TLR/MyD88 signaling together with COX-2/PGE2 pathway will be an effective preventive strategy for gastric cancer. Cancer Prev Res; 9(3); 253–63. ©2016 AACR.

Supplementary Figure Legends.

Supplementary Methods and Figure legend.

Expression levels of TLR2 and CD14 in human and mouse gastric tumors.

IPA analysis of human gastric cancer subtypes.

Gastric cancer is the fifth most common malignancy and the third leading cause of cancer-related deaths worldwide. Chemotherapies against gastric cancer often fail, with cancer recurrence due potentially to the persistence of cancer stem cells. This unique subpopulation of cells in tumors possesses the ability to self-renew and dedifferentiate. These cancer stem cells are critical for initiation, maintenance, metastasis, and relapse of cancers; however, the molecular mechanisms supporting cancer stemness remain largely unknown. Increased kinase and decreased phosphatase activity are hallmarks of oncogenic signaling. Protein phosphatase 2A (PP2A) functions as a tumor-suppressor enzyme, and elevated levels of SET/I2PP2A, an endogenous PP2A protein inhibitor, are correlated with poor prognosis of several human cancers. Here, it was determined that SET expression was elevated in tumor tissue in a gastric cancer mouse model system, and SET expression was positively correlated with poor survival of human gastric cancer patients. Mechanistically, SET knockdown decreased E2F1 levels and suppressed the stemness of cancer cell lines. Immunoprecipitations show SET associated with the PP2A–B56 complex, and the B56 subunit interacted with the E2F1 transcription factor. Treatment of gastric cancer cells with the SET-targeting drug OP449 increased PP2A activity, decreased E2F1 protein levels, and suppressed stemness of cancer cells. These data indicate that a SET/PP2A/E2F1 axis regulates cancer cell stemness and is a potential target for gastric cancer therapy.Implications: This study highlights the oncogenic role of SET/I2PP2A in gastric cancer and suggests that SET maintains cancer cell stemness by suppressing PP2A activity and stabilizing E2F1. Mol Cancer Res; 16(3); 554–63. ©2018 AACR.

This file contains detailed material and methods, and supplemental data related with Fig. 1g, Fig. 2a, b, Fig. 3c, d, Fig. 4a, b, c, Fig. 5c

Loss of parietal cells initiates the development of spasmolytic polypeptide–expressing metaplasia (SPEM), a precancerous lesion in stomach. CD44 variant (CD44v) that enhances the ability to defend against reactive oxygen species (ROS) in epithelial cells is expressed de novo in SPEM of K19-Wnt1/C2mE mice, a transgenic model of gastric tumorigenesis, and is required for the efficient development of SPEM and gastric tumor in these animals. The role of ROS and its downstream signaling in CD44-dependent gastric tumorigenesis has remained unknown, however. With the use of the K19-Wnt1/C2mE mouse, we now show that parietal cells in the inflamed stomach are highly sensitive to oxidative stress and manifest activation of p38MAPK signaling by ROS. Oral treatment with the antioxidant ascorbic acid or genetic ablation of the Ink4a/Arf locus, a major downstream target of ROS-p38MAPK signaling, inhibited parietal cell loss and the subsequent gastric tumorigenesis. Our results indicate that signaling activated by oxidative stress in parietal cells plays a key role in CD44-dependent gastric tumorigenesis. Cancer Prev Res; 8(6); 492–501. ©2015 AACR.

Histological diagnosis of the primary tumors

Immune cell infiltration into metastasized liver tumors

The content of this file containing Supplementary Figures (and a Supplementary Table) provides additional (and essential) data supporting our conclusions that the ASC inflammasome/caspase-1/IL-18 axis promotes gastric tumorigenesis.

Colorectal cancer is driven by the accumulation of driver mutations, but the contributions of specific mutations to different steps in malignant progression are not fully understood. In this study, we generated mouse models harboring different combinations of key colorectal cancer driver mutations (Apc, Kras, Tgfbr2, Trp53, Fbxw7) in intestinal epithelial cells to comprehensively investigate their roles in the development of primary tumors and metastases. ApcΔ716 mutation caused intestinal adenomas and combination with Trp53R270H mutation or Tgfbr2 deletion induced submucosal invasion. The addition of KrasG12D mutation yielded epithelial–mesenchymal transition (EMT)-like morphology and lymph vessel intravasation of the invasive tumors. In contrast, combinations of ApcΔ716 with KrasG12D and Fbxw7 mutation were insufficient for submucosal invasion, but still induced EMT-like histology. Studies using tumor-derived organoids showed that KrasG12D was critical for liver metastasis following splenic transplantation, when this mutation was combined with either ApcΔ716 plus Trp53R270H or Tgfbr2 deletion, with the highest incidence of metastasis displayed by tumors with a ApcΔ716 KrasG12D Tgfbr2−/− genotype. RNA sequencing analysis of tumor organoids defined distinct gene expression profiles characteristic for the respective combinations of driver mutations, with upregulated genes in ApcΔ716 KrasG12D Tgfbr2−/− tumors found to be similarly upregulated in specimens of human metastatic colorectal cancer. Our results show how activation of Wnt and Kras with suppression of TGFβ signaling in intestinal epithelial cells is sufficient for colorectal cancer metastasis, with possible implications for the development of metastasis prevention strategies.Significance: These findings illuminate how key driver mutations in colon cancer cooperate to drive the development of metastatic disease, with potential implications for the development of suitable prevention strategies. Cancer Res; 78(5); 1334–46. ©2017 AACR.

Inflammasomes are key regulators of innate immunity in chronic inflammatory disorders and autoimmune diseases, but their role in inflammation-associated tumorigenesis remains ill-defined. Here we reveal a protumorigenic role in gastric cancer for the key inflammasome adaptor apoptosis-related speck-like protein containing a CARD (ASC) and its effector cytokine IL18. Genetic ablation of ASC in the gp130F/F spontaneous mouse model of intestinal-type gastric cancer suppressed tumorigenesis by augmenting caspase-8-like apoptosis in the gastric epithelium, independently from effects on myeloid cells and mucosal inflammation. This phenotype was characterized by reduced activation of caspase-1 and NF-κB activation and reduced expression of mature IL18, but not IL1β, in gastric tumors. Genetic ablation of IL18 in the same model also suppressed gastric tumorigenesis, whereas blockade of IL1β and IL1α activity upon genetic ablation of the IL1 receptor had no effect. The specific protumorigenic role for IL18 was associated with high IL18 gene expression in the gastric tumor epithelium compared with IL1β, which was preferentially expressed in immune cells. Supporting an epithelial-specific role for IL18, we found it to be highly secreted from human gastric cancer cell lines. Moreover, IL18 blockade either by a neutralizing anti-IL18 antibody or by CRISPR/Cas9-driven deletion of ASC augmented apoptosis in human gastric cancer cells. In clinical specimens of human gastric cancer tumors, we observed a significant positive correlation between elevated mature IL18 protein and ASC mRNA levels. Collectively, our findings reveal the ASC/IL18 signaling axis as a candidate therapeutic target in gastric cancer.Significance: Inflammasome activation that elevates IL18 helps drive gastric cancer by protecting cancer cells against apoptosis, with potential implications for new therapeutic strategies in this setting. Cancer Res; 78(5); 1293–307. ©2017 AACR.

Purpose: The majority of gastric cancer patients are diagnosed with late-stage disease, for which distinct molecular subtypes have been identified that are potentially amenable to targeted therapies. However, there exists no molecular classification system with prognostic power for early-stage gastric cancer (EGC) because the molecular events promoting gastric cancer initiation remain ill-defined.Experimental Design: miRNA microarrays were performed on gastric tissue from the gp130F/F preclinical EGC mouse model, prior to tumor initiation. Computation prediction algorithms were performed on multiple data sets and independent gastric cancer patient cohorts. Quantitative real-time PCR expression profiling was undertaken in gp130F/F-based mouse strains and human gastric cancer cells genetically engineered for suppressed activation of the oncogenic latent transcription factor STAT3. Human gastric cancer cells with modulated expression of the miR-200 family member miR-429 were also assessed for their proliferative response.Results: Increased expression of miR-200 family members is associated with both tumor initiation in a STAT3-dependent manner in gp130F/F mice and EGC (i.e., stage IA) in patient cohorts. Overexpression of miR-429 also elicited contrasting pro- and antiproliferative responses in human gastric cancer cells depending on their cellular histologic subtype. We also identified a miR-200 family–regulated 15-gene signature that integrates multiple key current indicators of EGC, namely tumor invasion depth, differentiation, histology, and stage, and provides superior predictive power for overall survival compared with each EGC indicator alone.Conclusions: Collectively, our discovery of a STAT3-regulated, miR-200 family–associated gene signature specific for EGC, with predictive power, provides a molecular rationale to classify and stratify EGC patients for endoscopic treatment. Clin Cancer Res; 24(6); 1459–72. ©2018 AACR.

These figures and tables contain supporting (and essential) data to confirm the clinical utility of the miR-200 family and signature in early gastric cancer, as well as its regulation by STAT3. Supplementary Figure S1. The association of WHO intestinal-type GC sub-classes and individual TNM stage with the expression of miR-200 family members and miR-21 in TCGA GC patients. Supplementary Figure S2. The association between patient survival and expression of miR- 200s and a complete network map of GSEA results generated from TCGA GC patients. Supplementary Figure S3. miR-429 promotes AGS cells proliferation and clonigenicity. Supplementary Figure S4. The association between patient survival and expression of individual genes from the miR-200 family-associated 15-gene signature. Supplementary Figure S5. STAT3 activation correlates with miR-429 and other miR-200 members in mouse and human gastric epithelial cells. Supplementary Figure S6. Generation of STAT3 knockout human GC lines, and STAT3- independent transcriptional regulation of miR-200 family members. Supplementary Table S1. Clinicopathological features and demographics of GC patients from TCGA cohort used for expression profiling of hsa-miR-429. Supplementary Table S2. Chi-square analysis between the miR-200 family 15-gene signature and conventional key prognostic factors using two independent cohorts. 2 Supplementary Table S3. Multivariate analysis of overall survival comparing the miR-200 family 15-gene signature and other conventional clinical parameters including histology and tumor grade (differentiation) using updated TCGA data.

Supplementary Figure 3 from Induction of Prostaglandin E2 Pathway Promotes Gastric Hamartoma Development with Suppression of Bone Morphogenetic Protein Signaling

Supplementary Figure 1 from Induction of Prostaglandin E2 Pathway Promotes Gastric Hamartoma Development with Suppression of Bone Morphogenetic Protein Signaling

Mutations in bone morphogenetic protein (BMP) receptor 1A (BMPR1A) are responsible for a subset of cases of juvenile polyposis (JP) syndrome that develops hamartomatous tumors in the gastrointestinal tract. Mouse genetic studies have shown that suppression of BMP signaling in the intestines causes JP-type hamartoma development. Here, we generated K19-Nog transgenic mice expressing noggin, a BMP antagonist, in gastric epithelium. However, inhibition of BMP signaling did not cause gastric phenotypes. We thus crossed K19-Nog with K19-C2mE mice that expressed Ptgs2 and Ptges in the stomach to generate compound transgenic mice. Expression of Ptgs2 and Ptges results in prostaglandin E2 (PGE2) biosynthesis, and both enzymes are induced in most human gastrointestinal tumors. Importantly, K19-Nog/C2mE compound mice developed gastric hamartomas that were morphologically similar to those found in JP with mucin-containing dilated cysts and inflammatory infiltration. Notably, treatment of K19-Nog/C2mE mice with a cyclooxygenase-2 inhibitor, celecoxib, significantly reduced tumor size with suppression of angiogenesis, suggesting that induction of the PGE2 pathway together with inhibition of BMP signaling is required for gastric hamartoma development. Moreover, microarray analyses revealed that canonical Wnt signaling target genes were not induced in K19-Nog/C2mE hamartomas, indicating that BMP inhibition and PGE2 induction lead to gastric hamartoma development independent of the Wnt/β-catenin pathway. These results, taken together, suggest that the PGE2 pathway is an effective preventive target against BMP-suppressed gastric hamartomas, as well as for Wnt/β-catenin–activated adenocarcinomas. [Cancer Res 2009;69(7):2729–33]

Supplementary Figure 2 from Induction of Prostaglandin E2 Pathway Promotes Gastric Hamartoma Development with Suppression of Bone Morphogenetic Protein Signaling

Supplementary Figure S3. Histology of intestines of Tgfbr2ÃŽ?IEC mice.

Supplementary Figure 4 from Induction of Prostaglandin E2 Pathway Promotes Gastric Hamartoma Development with Suppression of Bone Morphogenetic Protein Signaling

Legends for Supplementary Figures S1-S6.

Supplementary Table 1 from Induction of Prostaglandin E2 Pathway Promotes Gastric Hamartoma Development with Suppression of Bone Morphogenetic Protein Signaling

Gastric cancer (GC) is strongly linked with chronic gastritis after Helicobacter pylori infection. Toll-like receptors (TLRs) are key innate immune pathogenic sensors that mediate chronic inflammatory and oncogenic responses. Here, we investigated the role of TLR9 in the pathogenesis of GC, including Helicobacter infection.TLR9 gene expression was profiled in gastric tissues from GC and gastritis patients and from the spontaneous gp130TLR9 expression was up-regulated in Helicobacter-infected gastric tissues from GC and gastritis patients and gp130Our data reveal that TLR9 promotes the initiating stages of GC and facilitates Helicobacter-induced gastric inflammation and hyperplasia, thus providing in vivo evidence for TLR9 as a candidate therapeutic target in GC.