Tumorigenesis In ApcMin Research Articles

Simulated Galactic Cosmic Radiation Exposure-Induced Mammary Tumorigenesis in ApcMin/+ Mice Coincides with Activation of ERα-ERRα-SPP1 Signaling Axis

Background: Exposure to galactic cosmic radiation (GCR) is a breast cancer risk factor for female astronauts on deep-space missions. However, the specific signaling mechanisms driving GCR-induced breast cancer have not yet been determined. Methods: This study aimed to investigate the role of the estrogen-induced ERα-ERRα-SPP1 signaling axis in relation to mammary tumorigenesis in female ApcMin/+ mice exposed to simulated GCR (GCRsim) at 100–110 days post-exposure. Results: In GCRsim-exposed mice, we observed marked elevations in serum estradiol, increased ductal overgrowth, ERα activation, and upregulation of ERα target genes with pro-tumorigenic functions in mammary tissues that was coupled with a higher mammary tumorigenesis, relative to control. Additionally, the ERα target gene Esrra, which encodes ERRα, was also upregulated along with its oncogenic target gene Spp1, indicating the activation of the ERα-ERRα-SPP1 axis in mouse mammary tissues after GCRsim exposure. Using a human tissue microarray and human breast cancer gene expression analysis, we also highlighted the conserved nature of the ERα-ERRα-SPP1 signaling in human breast cancer development. Conclusions: We identified the ERα-ERRα-SPP1 signaling axis as a potential key mediator in GCR-induced breast cancer with conserved activation in human breast cancer. These findings suggest that targeting this pathway could serve as a potential target for therapeutic intervention to safeguard female astronauts during and after a prolonged outer space mission.

The eIF3a translational control axis in the Wnt/β-catenin signaling pathway and colon tumorigenesis

Translational initiation in protein synthesis is an important regulatory step in gene expression and its dysregulation may result in diseases such as cancer. Translational control by eIF4E/4E-BP has been well studied and contributes to mTOR signaling in various biological processes. Here, we report a novel translational control axis in the Wnt/β-catenin signaling pathway in colon tumorigenesis by eIF3a, a Yin-Yang factor in tumorigenesis and prognosis. We show that eIF3a expression is upregulated in human colon cancer tissues, pre-cancerous adenoma polyps, and associates with β-catenin level and APC mutation in human samples, and that eIF3a overexpression transforms intestinal epithelial cells. We also show that eIF3a expression is regulated by the Wnt/β-catenin signaling pathway with an active TCF/LEF binding site in its promoter and that eIF3a knockdown inhibits APC mutation-induced spontaneous colon tumorigenesis in APCmin/+ mice. Together, we conclude that eIF3a upregulation in colon cancer is due to APC mutation and it participates in colon tumorigenesis by adding a translational control axis in the Wnt/β-catenin signaling pathway and that it can serve as a potential target for colon cancer intervention.

Peptostreptococcus stomatis promotes colonic tumorigenesis and receptor tyrosine kinase inhibitor resistance by activating ERBB2-MAPK

Peptostreptococcus stomatis (P.stomatis) is enriched in colorectal cancer (CRC), but its causality and translational implications in CRC are unknown. Here, we show that P.stomatis accelerates colonic tumorigenesis in ApcMin/+ and azoxymethane/dextran sodium sulfate (AOM-DSS) models by inducing cell proliferation, suppressing apoptosis, and impairing gut barrier function. P.stomatis adheres to CRC cells through its surface protein fructose-1,6-bisphosphate aldolase (FBA) that binds to the integrin α6/β4 receptor on CRC cells, leading to the activation of ERBB2 and the downstream MEK-ERK-p90 cascade. Blockade of the FBA-integrin α6/β4 abolishes ERBB2-mitogen-activated protein kinase (MAPK) activation and the protumorigenic effect of P.stomatis. P.stomatis-driven ERBB2 activation bypasses receptor tyrosine kinase (RTK) blockade by EGFR inhibitors (cetuximab, erlotinib), leading to drug resistance in xenograft and spontaneous CRC models of KRAS-wild-type CRC. P.stomatis also abrogates BRAF inhibitor (vemurafenib) efficacy in BRAFV600E-mutant CRC xenografts. Thus, we identify P.stomatis as an oncogenic bacterium and a contributory factor for non-responsiveness to RTK inhibitors in CRC.

Yogurt Prevents Colorectal Tumorigenesis in ApcMin/+ Mice.

Yogurt consumption is related to a decreased risk of colorectal cancer (CRC), but whether such association is causal remains unclear. Patients with familial adenomatous polyposis (FAP) are at increased risk of CRC development. Here, the study investigates the efficacy of yogurt for intestinal polyposis chemoprevention in ApcMin/+ mice, a preclinical model for human FAP. A 10-week yogurt supplementation (15gkg-1) in ApcMin/+ mice significantly reduces the intestinal polyp number (6.50±0.97 versus 1.80±0.49; p<0.001) compared to controls. 16S rRNA gene-based microbiota analysis suggests that yogurt supplementation may greatly modulate the gut microbiome composition, especially in the relative abundance of Lactobacillus and Bifidobacterium. Importantly, the fecal concentration of d-lactate (d-Lac, 0.39±0.04µmolg-1 versus 8.14±0.62µmolg-1; p < 0.001) is boosted by yogurt, while oral administration with d-Lac (125 or 250mgkg-1) reduces the polyp number by 71.43% or 77.14% (p<0.001), respectively. The study also observes that d-Lac does not affect cell viability and anchorage-independence in CRC cells, but it greatly suppresses epidermal growth factor (EGF) or 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell transformation in preneoplastic cells. Mechanistically, it demonstrates that d-Lac may attenuate epithelial cell transformation by targeting PI3K/AKT/β-catenin axis. Yogurt protects against intestinal polyposis in ApcMin/+ mice, and d-Lac may partially account for the chemopreventive effects above.

Abstract 6693: Deleted in malignant brain tumors 1 (DMBT1) glycoprotein is lost in colonic dysplasia

Abstract Colorectal cancer (CRC) is the third most common cancer in the United States and is responsible for more than 50,000 deaths annually. Emerging evidence strongly supports a causal role for specific pro-carcinogenic driver bacteria within the colonic microbiota. Invasive bacterial biofilms may initiate or accelerate CRC through epithelium-autonomous or inflammation-dependent mechanisms. To better understand host-microbe interactions during colonic tumorigenesis, we combined single-cell RNA-sequencing (scRNA-seq), spatial transcriptomics, and immunofluorescence to define the molecular spatial organization of colonic tissue from germ-free ApcMin/+ mice colonized with bacteria from human biofilm-associated CRC. In absorptive colonocytes, differential gene expression analysis showed the gastric metaplasia-associated glycoprotein Deleted in Malignant Brain Tumors 1 (DMBT1) is highly upregulated by C. difficile. Surprisingly, our spatial transcriptomic analysis showed DMBT1 was dramatically downregulated in dysplastic foci compared with normal-appearing tissue. We show that DMBT1 protein is downregulated in 100% of dysplastic foci across 3 different mouse models of colonic tumorigenesis: C. difficile-associated tumorigenesis in ApcMin/+, azoxymethane/dextran sodium sulfate, and Lrig1CreER/+;Apcfl/+ mice (n = 57 foci from 11 mice). Immunofluorescent staining of DMBT1 is markedly downregulated compared with normal adjacent crypts. Using scRNA-seq data and tissue microscopy in human CRC, we confirmed the same pattern of downregulated DMBT1 expression in dysplastic crypts compared with normal-appearing crypts. We present data from a human mucosal biofilm-associated colonic tumorigenesis murine model at single-cell resolution to reveal interesting cell type-specific transitions and generalizable mechanisms of tumorigenesis. We hypothesize that DMBT1 is a component of the gut epithelial response to pathogens and a critical regulator of proliferation and differentiation during post-injury restitution. We are now functionally testing how the loss of DMBT1 impacts tumorigenesis using human organoids. Ultimately, these studies aim to reveal novel biomarkers and/or targets for therapeutic intervention in CRC. Citation Format: Emily H. Green, Subhag R. Kotrannavar, Megan E. Rutherford, Harsimran Kaur, Hannah M. Lunnemann, Cody N. Heiser, Shaoguang Wu, Hua Ding, J. Alan Simmons, Xiao Liu, D. Borden Lacy, Martha J. Shrubsole, Qi Liu, Ken S. Lau, Cynthia L. Sears, Robert J. Coffey, Julia L. Drewes, Nicholas O. Markham. Deleted in malignant brain tumors 1 (DMBT1) glycoprotein is lost in colonic dysplasia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6693.

Aspirin, Risk of Colorectal Cancer, & Genetic Risk-Reply.

We appreciated the letter by Koulaouzidis and colleagues, which highlights the need for further studies to understand the mechanistic basis for aspirin's effect on colorectal cancer. Alongside their summary of our work (1) in the context of prior studies, they suggest that the effect of aspirin on gut microbiota should be examined. We agree that this is a high priority. As a rationale, they highlight research that shows aspirin appears to alter the gut microbiome to promote bacteria that are anti-inflammatory, thereby reducing colorectal cancer risk (2). We would further add that preclinical studies identify specific microbes that promote a proinflammatory environment, leading to induction of the enzymes that synthesize oncogenic prostaglandins which are inhibited by aspirin. Our group has also demonstrated that aspirin significantly inhibits tumorigenesis in ApcMin/+ mice inoculated with F. nucleatum and adenomas in aspirin users have significantly less Fusobacterium compared with nonaspirin users (3–5). These results are further supported by recent findings that aspirin treatment raises aspirin plasma concentrations and lowers tumor burden in microbiota-depleted mouse colorectal cancer models (ApcMin/+ and AOM/DSS), compared with microbiome-intact models and causes shifts in fecal metagenomic profiles of microbiome-intact mice that modulate aspirin bioavailability (6). Finally, a small randomized trial showed that aspirin alters the relative abundance of gut bacteria associated with colorectal cancer (7).Beyond playing a role in the development progression of colorectal cancer (8), the gut microbiome is being exploited to develop fecal microbial markers as a possible biomarker of colorectal cancer risk (9). If these studies are successful, gut microbiome risk markers could be leveraged alongside other risk measures including diet, age, and polygenic risk score to help identify patients who may have a more optimal risk-benefit profile for aspirin prevention.See the original Letter to the Editor, p. 701A.T. Chan reports personal fees from Bayer Pharma AG, Boehringer Ingelheim; grants and personal fees from Pfizer Inc.; and grants from Zoe, Ltd. outside the submitted work. No disclosures were reported by the other author.

Akkermansia muciniphila in inflammatory bowel disease and colorectal cancer.

Akkermansia muciniphila in inflammatory bowel disease and colorectal cancer.

ZnO nanoparticles promote the malignant transformation of colorectal epithelial cells in APCmin/+ mice

As the use of zinc oxide nanoparticles (ZnO NPs) in everyday products grows, so does concern about health risks. However, no findings on the gastrointestinal toxicity of ZnO NPs have been published. We investigated the possible malignant transformation of ZnO NPs in the mice’s colonic tissues using the APCmin/+ mouse model with a premalignant lesion in intestinal epithelial cells. Higher doses and long-term oral exposure to ZnO NPs were found to mildly promote colonic inflammation in WT mice, while they moderately or strongly exacerbated the severity of chronic inflammation and tumorigenesis in APCmin/+ mice with intestinal adenomatous polyposis. The ZnO NPs-induced inflammation and tumorigenesis in colonic epithelial cells was linked to the activation of CXCR2/NF-κB/STAT3/ERK and AKT pathways. Analysis of the ZnO NPs-exacerbated intestinal adenomatous polyposis in APCmin/+ mice revealed that ZnO NPs could activate the APC-driven Wnt/β-catenin signaling pathway, exacerbating intestinal tumorigenesis. In fact, ZnO NPs have been shown to increase intestinal inflammation and tumorigenesis in APCmin/+ mice by releasing free Zn2+. In WT mice, a low dose of ZnO NPs (26 mg/kg/day) did not cause intestinal inflammation. In conclusion, higher doses and prolonged exposure to ZnO NPs promote the malignant transformation of precancerous epithelial cells.

A. Muciniphila Suppresses Colorectal Tumorigenesis by Inducing TLR2/NLRP3-Mediated M1-Like TAMs.

The interplay between gut microbiota and the host immune system is emerging as a factor in the pathogenesis of colorectal cancer. Here, we set out to identify the effect of Akkermansia muciniphila (A. muciniphila) on colorectal cancer pathogenesis. A. muciniphila abundance was significantly reduced in patients with colorectal cancer from two independent clinical cohorts and the GMrepo dataset. Supplementation with A. muciniphila suppressed colonic tumorigenesis in ApcMin/+ mice and the growth of implanted HCT116 or CT26 tumors in nude mice. Mechanistically, A. muciniphila facilitated enrichment of M1-like macrophages in an NLRP3-dependent manner in vivo and in vitro. As a consequence, NLRP3 deficiency in macrophages attenuated the tumor-suppressive effect of A. muciniphila. In addition, we revealed that TLR2 was essential for the activation of the NF-κB/NLRP3 pathway and A. muciniphila induced M1-like macrophage response. We observed positive correlations between M1-like macrophages, NLRP3/TLR2 and A. muciniphila in patients with colorectal cancer, which corroborated these findings. In summary, A. muciniphila-induced M1-like macrophages provide a therapeutic target in the colorectal cancer tumor microenvironment.

Unveiling the Roles of Low-Density Lipoprotein Receptor-Related Protein 6 in Intestinal Homeostasis, Regeneration and Oncogenesis.

Intestinal epithelial self-renewal is tightly regulated by signaling pathways controlling stem cell proliferation, determination and differentiation. In particular, Wnt/β-catenin signaling controls intestinal crypt cell division, survival and maintenance of the stem cell niche. Most colorectal cancers are initiated by mutations activating the Wnt/β-catenin pathway. Wnt signals are transduced through Frizzled receptors and LRP5/LRP6 coreceptors to downregulate GSK3β activity, resulting in increased nuclear β-catenin. Herein, we explored if LRP6 expression is required for maintenance of intestinal homeostasis, regeneration and oncogenesis. Mice with an intestinal epithelial cell-specific deletion of Lrp6 (Lrp6IEC-KO) were generated and their phenotype analyzed. No difference in intestinal architecture nor in proliferative and stem cell numbers was found in Lrp6IEC-KO mice in comparison to controls. Nevertheless, using ex vivo intestinal organoid cultures, we found that LRP6 expression was critical for crypt cell proliferation and stem cell maintenance. When exposed to dextran sodium sulfate, Lrp6IEC-KO mice developed more severe colitis than control mice. However, loss of LRP6 did not affect tumorigenesis in ApcMin/+ mice nor growth of human colorectal cancer cells. By contrast, Lrp6 silencing diminished anchorage-independent growth of BRafV600E-transformed intestinal epithelial cells (IEC). Thus, LRP6 controls intestinal stem cell functionality and is necessary for BRAF-induced IEC oncogenesis.

Celecoxib alleviates zinc deficiency-promoted colon tumorigenesis through suppressing inflammation.

Accumulating evidence has shown that dietary zinc deficiency (ZD) increases the risk of various cancers including esophageal and gastric cancer. However, the role of ZD in colon tumorigenesis is unknown and the related mechanisms need to be investigated. Apcmin/+ mice, widely used to mimic the spontaneous process of human intestinal tumor, were used to construct a ZD mice model in this study. Inflammatory mediators such as COX-2, TNF-α, CCL, CXCL, and IL chemokines families were evaluated using real-time PCR and Enzyme-linked immunosorbent assay (ELISA). Besides, the immunoreactivities of cyclin D1, PCNA, and COX-2 in the colon were detected by immunohistochemistry. We found that zinc deficiency could promote colon tumorigenesis in Apcmin/+ mice. The mechanisms are involved in the upregulation of inflammatory mediators: COX-2, TNF-α, CCL, CXCL, and IL chemokines families. Administration of celecoxib, a selective COX-2 inhibitor, decreased colon tumorigenesis in Apcmin/+ mice via inhibiting the inflammatory mediators. ZD plays an important role in the process of colon cancers of Apcmin/+ mice. Celecoxib attenuates ZD-induced colon tumorigenesis in Apcmin/+ mice by inhibiting the inflammatory mediators. Our novel finding would provide potential prevention of colorectal tumor-induced by ZD.

MLKL inhibits intestinal tumorigenesis by suppressing STAT3 signaling pathway.

Mixed lineage kinase domain-like protein (MLKL) plays an important role in necroptosis, but the role and mechanism of MLKL in intestinal tumorigenesis remain unclear. Here, we found that hematopoietic- and nonhematopoietic-derived MLKL affected intestinal inflammation, but nonhematopoietic-derived MLKL primarily inhibited intestinal tumorigenesis. Loss of MLKL enhanced intestinal regeneration and the susceptibility to intestinal tumorigenesis in Apcmin/+ mice by hyperactivating the Janus kinase 2 (JAK2)/ signal transducer and activator of transcription 3 (STAT3) axis. Furthermore, MLKL deficiency increased interleukin-6 (IL-6) production in dendritic cells. Administration of anti-IL-6R antibody therapy reduced intestinal tumorigenesis in Apcmin/+Mlkl-/- mice. Notably, low MLKL expression in human colorectal tumors, which enhanced STAT3 activation, was associated with decreased overall survival. Together, our results reveal that MLKL exhibits a suppressive effect during intestinal tumorigenesis by suppressing the IL-6/JAK2/STAT3 signals.

Abstract 396: The bile acid receptor FXR suppress colitis-induced colon cancer

Abstract Colorectal cancer (CRC) is the third most common cancer and a major cause of cancer related death. Colitis-associated colorectal carcinoma (CAC) is a type of CRC that develops in patients with inflammatory bowel disease (IBD), and is associated with chronic, idiopathic intestinal inflammation. While the underlying cause(s) are poorly understood, environmental factors including high fat diets and aberrant intestinal immune responses contribute to disease progression. Bile acid (BA) overproduction is implicated in diarrhea associated with IBD and CAC. As early sensors of dietary status, BAs are critical mediators of gut inflammation and immunity, in part through their ability to affect the activity of the Farnesoid X Receptor (FXR). FXR is considered the master regulator of BA homeostasis, also a key modulator of the pro- and anti-inflammatory responses in the intestinal epithelium, whose function severely compromised in both CAC patients and in AOM/DSS mouse model. Here, we show that inflammation-induced epithelial abnormalities altered the BAs profile, given the role of the crypt-villus architecture in establishing a BA gradient necessary for homeostasis. In addition, AOM/DSS treatment enhanced immune cell infiltration, as well as induced the formation of massive tumors in the colon. Given that intestinally-restricted FXR agonist FexD can reduced tumorigenesis in APCmin/+ mice, we also treated AOM/DSS mice with FexD. Notably, FexD activated FXR signaling pathway and restored BA homeostasis. Further, it reduced fecal bleeding, intestinal permeability, and decreased serum levels of the late carcinogenesis markers CEA and CA19. Treatment of FexD also resulted in a smaller spleen and reduced pro-inflammatory cytokine levels such as IL17 and IL6. The present study highlights the role of FXR in inflammation induced colon cancer, opening new therapeutic avenues for the treatment of CAC. Citation Format: Ting Fu, Ronald Evans. The bile acid receptor FXR suppress colitis-induced colon cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 396.

Protons Show Greater Relative Biological Effectiveness for Mammary Tumorigenesis with Higher ERα- and HER2-Positive Tumors Relative to γ-rays in APCMin/+ Mice

Exposure to ionizing radiation increases risk of breast cancer. Although proton radiation is encountered in outer space and in medicine, we do not fully understand breast cancer risks from protons owing to limited invivo data. The purpose of this study was to comparatively assess the effects of γ-rays and protons on mammary tumorigenesis in APCMin/+ mice. Female APCMin/+ mice were exposed to 1 GeV protons (1.88 or 4.71 Gy) and 137Cs γ-rays (2 or 5 Gy). Mice were euthanized 100 to 110 days after irradiation, at which point mammary tumors were scored, tumor grades were assessed, and relative biological effectiveness was calculated. Molecular phenotypes were determined by assessing estrogen receptor α (ERα) and human epidermal growth factor receptor 2 (HER2) status. ERα downstream signaling was assessed by immunohistochemistry. Exposure to proton radiation led to increased mammary tumor frequency at both proton radiation doses compared with γ-rays. The calculated relative biological effectiveness for proton radiation-induced mammary tumorigenesis was 3.11 for all tumors and >5 for malignant tumors relative to γ-rays. Tumor frequency per unit of radiation was higher at the lower dose, suggesting a saturation effect at the higher dose. Protons induced more adenocarcinomas relative to γ-rays, and proton-induced tumors show greater ERα and HER2 positivity and higher activation of the ERα downstream PI3K/Akt and cyclin D1 pathways relative to γ-rays. Our data demonstrate that protons pose a higher risk of mammary tumorigenesis relative to γ-rays. We also show that proton radiation-induced tumors in APCMin/+ mice are ERα- and HER2-positive, which is consistent with our previous data on radiation-induced estrogenic response in wild-type mice. Although this study establishes APCMin/+ as a model with adequate signal-to-noise ratio for space radiation-induced mammary tumorigenesis, further studies will be required to address the uncertainties in space radiation-induced breast cancer risk estimation.

The role of the small intestine in modulating metabolism and inflammation in atherosclerosis and cancer.

To discuss recent findings on the importance of the small intestine in modulating metabolism and inflammation in atherosclerosis and cancer. Integrin β7 natural gut intraepithelial T cells modulated metabolism and accelerated atherosclerosis in mice. Reducing the generation of lysophospholipids in the small intestine mimicked bariatric surgery and improved diabetes. Enterocyte-specific knockdown of stearoyl-CoA desaturase-1 significantly improved dyslipidemia in LDL receptor null (Ldlr) mice fed a Western diet. Adding a concentrate of tomatoes transgenic for the apolipoprotein A-I mimetic peptide 6F to the chow of wild-type mice altered lipid metabolism in the small intestine, preserved Notch signaling and reduced tumor burden in mouse models. The phospholipid-remodeling enzyme Lpcat3 regulated intestinal stem cells and progenitor cells by stimulating cholesterol biosynthesis; increasing cholesterol in the diet or through genetic manipulation promoted tumorigenesis in Apc mice. The small intestine is important for regulating metabolism and inflammation in animal models of both atherosclerosis and cancer.

Fisetin and 5-fluorouracil: Effective combination for PIK3CA-mutant colorectal cancer.

The normal colon epithelium is transformed into its neoplastic counterpart through a series of genetic alterations in driver genes including activating mutations in PIK3CA. Treatment often involves surgery followed by 5-fluorouracil (5-FU) based therapy, which has limited efficiency and serious side effects. We sought to determine whether fisetin, a dietary flavonoid, alone or in combination with 5-FU affected tumorigenesis in the mammalian intestine. We first determined the effect of fisetin, 5-FU or their combination on PIK3CA-mutant and PIK3CA wild-type colon cancer cells by assessing cell viability, colony formation, apoptosis and effects on PI3K/AKT/mTOR signaling. Treatment of PIK3CA-mutant cells with fisetin and 5-FU reduced the expression of PI3K, phosphorylation of AKT, mTOR, its target proteins, constituents of mTOR signaling complex and this treatment increased the phosphorylation of AMPKα. We then determined whether fisetin and 5-FU together or singly affected tumorigenesis in ApcMin/+ mice that also express constitutively active PI3K in the distal small intestine and colon. Tumor incidence was markedly lower in fisetin-treated FC1 3K1 ApcMin/+ mice that also express constitutively active PI3K in distal small intestine and colon, as compared to control animals, indicating that fisetin is a strong preventive agent. In addition, the combination of fisetin and 5-FU also reduced the total number of intestinal tumors. Fisetin could be used as a preventive agent plus an adjuvant with 5-FU for the treatment of PIK3CA-mutant colorectal cancer.

The CXCR7/CXCR4 heterodimer induced histone demethylation: A new mechanism of colorectal tumorigenesis

PurposeBoth chemokine receptors (CXCR) 7 and 4 are known to be involved in a vast array of pathological events in the development cancer. However, it is not yet known whether the CXCR7/CXCR4 heterodimer can form in vivo, and if it does, the functional difference between CXCR7 monomer and the CXCR7/CXCR4 heterodimer.Experimental DesignThe expression of two CXCRs, CXCR7/CXCR4 heterodimer and histone demethylase JMJD2A in human colorectal rectal cancer (CRC) tissue was detected by western blot and immunohistochemistry. We then studied the role of the CXCR7/CXCR4 heterodimer in CRC tumorigenesis in Villin‐CXCR7‐CXCR4 transgenic mice and APCMin/+/villin‐CXCR7‐CXCR4 mice.ResultsCXCR 7 and 4 can form heterodimers in vivo and promote colorectal tumorigenesis through histone demethylation. Compared with adjacent non‐neoplastic tissue, human colorectal rectal cancer (CRC) tissue showed a significantly higher expression of CXCR4 and CXCR7, which was co‐localized in the cancer cell epithelium. CXCR/CXCR4 heterodimerization was associated with increased histone demethylase JMJD2A. Villin‐CXCR7‐CXCR4 transgenic mice presented a greater degree of exacerbated colitis and tumorigenesis than villin‐CXCR7 and villin‐CXCR4 mice. The CXCR7/CXCR4 heterodimer also increased APC mutation‐driven colorectal tumorigenesis in APCMin/+/villin‐CXCR7‐CXCR4 mice. Further analysis showed that the CXCR7/CXCR4 heterodimer induced nuclear β‐arrestin 1 recruitment and histone demethylase JMJD2A, leading to histone demethylation and increased transcription of inflammatory factors and oncogenes.ConclusionOur data reveal a novel mechanism of colorectal tumorigenesis through CXCR7/CXCR4 heterodimer‐induced histone demethylation. Inhibition of CXCR7/CXCR4 heterodimer‐induced histone demethylation could be an effective strategy for cancer treatment.Support or Funding InformationThis work was supported by Natural Science Foundation of China (91629303) The graphical abstractimageThe graphical abstractThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

CXCR7/CXCR4 heterodimer-induced histone demethylation: a new mechanism of colorectal tumorigenesis.

Both chemokine receptors (CXCRs) 7 and 4 can facilitate immune cell migration and mediate a vast array of physiological and pathological events. Herein we report, in both human and animal studies, that these two CXCRs can form heterodimers in vivo and promote colorectal tumorigenesis through histone demethylation. Compared with adjacent non-neoplastic tissue, human colorectal cancer (CRC) tissue showed a significant higher expression of CXCR4 and CXCR7, which was colocalized in the cancer cell epithelium. The CXCR/CXCR4 heterodimerization was associated with increased histone demethylase JMJD2A. Villin-CXCR7-CXCR4 transgenic mice demonstrated a greater degree of exacerbated colitis and tumorigenesis than villin-CXCR7 and villin-CXCR4 mice. The CXCR7/CXCR4 heterodimerization also promoted APC mutation-driven colorectal tumorigenesis in APCMin/+/villin-CXCR7-CXCR4 mice. Further analysis showed that the CXCR7/CXCR4 heterodimer induced nuclear βarr1 recruitment and histone demethylase JMJD2A, leading to histone demethylation and resulting in transcription of inflammatory factors and oncogenes. This study uncovered a novel mechanism of colorectal tumorigenesis through the CXCR7/CXCR4 heterodimer-induced histone demethylation. Inhibition of CXCR7/CXCR4 heterodimer-induced histone demethylation could be an effective strategy for the prevention and treatment of colorectal cancer.

High-throughput metabolomics for discovering metabolic biomarkers from intestinal tumorigenesis in APC min/+ mice based on liquid chromatography/mass spectrometry

As a major public health concern, colon cancer is one of the most common cancer types, which is also the second cause of cancer death in developed countries and the third most common cancer in other parts of the world. It was reported that patients diagnosed at early stage have a chance to obtain 5-year survival rates at least compared to patients with late stage. Facing the multistep process in intestinal tumorigenesis, there is an urgent need to develop more effective early detection strategies for ameliorating the patient clinical outcome. Metabolomics open up a novel avenue of seeking valuable potential biomarkers for assessing disease severity and prognosticating course by dynamic snapshot of small molecule metabolites. The study aims to provide deeper insights into the discovery, identification and functional pathways analysis of differentially expressed metabolites in intestinal tumorigenesis in APC min/+ mice used by the serum metabolomics, and bring about useful information for further effective prevention and treatment of the disease. 17 marker metabolites and related metabolism pathway were identified using non-targeted metabolomics based on liquid chromatography/mass spectrometry (LC/MS) associated with multivariate statistical analysis. The ingenuity pathway analysis platform involved multiple-pathways was applied to metabolic network analysis for further understanding the relationship between functional metabolic pathways and disease.

MACROD2 Haploinsufficiency Impairs Catalytic Activity of PARP1 and Promotes Chromosome Instability and Growth of Intestinal Tumors.

ADP-ribosylation is an important posttranslational protein modification that regulates diverse biological processes, controlled by dedicated transferases and hydrolases. Here, we show that frequent deletions (∼30%) of the MACROD2 mono-ADP-ribosylhydrolase locus in human colorectal cancer cause impaired PARP1 transferase activity in a gene dosage-dependent manner. MACROD2 haploinsufficiency alters DNA repair and sensitivity to DNA damage and results in chromosome instability. Heterozygous and homozygous depletion of Macrod2 enhances intestinal tumorigenesis in ApcMin/+ mice and the growth of human colorectal cancer xenografts. MACROD2 deletion in sporadic colorectal cancer is associated with the extent of chromosome instability, independent of clinical parameters and other known genetic drivers. We conclude that MACROD2 acts as a haploinsufficient tumor suppressor, with loss of function promoting chromosome instability, thereby driving cancer evolution.Significance: Chromosome instability (CIN) is a hallmark of cancer. We identify MACROD2 deletion as a cause of CIN in human colorectal cancer. MACROD2 loss causes repression of PARP1 activity, impairing DNA repair. MACROD2 haploinsufficiency promotes CIN and intestinal tumor growth. Our results reveal MACROD2 as a major caretaker tumor suppressor gene. Cancer Discov; 8(8); 988-1005. ©2018 AACR.See related commentary by Jin and Burkard, p. 921This article is highlighted in the In This Issue feature, p. 899.