Tamas A. Gonda

Bone Marrow-Derived Myofibroblasts Contribute to the Mesenchymal Stem Cell Niche and Promote Tumor Growth

Carcinoma-associated fibroblasts (CAFs) that express α-smooth muscle actin (αSMA) contribute to cancer progression, but their precise origin and role are unclear. Using mouse models of inflammation-induced gastric cancer, we show that at least 20% of CAFs originate from bone marrow (BM) and derive from mesenchymal stem cells (MSCs). αSMA+ myofibroblasts (MFs) are niche cells normally present in BM and increase markedly during cancer progression. MSC-derived CAFs that are recruited to the dysplastic stomach express IL-6, Wnt5α and BMP4, show DNA hypomethylation, and promote tumor growth. Moreover, CAFs are generated from MSCs and are recruited to the tumor in a TGF-β- and SDF-1α-dependent manner. Therefore, carcinogenesis involves expansion and relocation of BM-niche cells to the tumor to create a niche to sustain cancer progression.

Molecular biology of cancer-associated fibroblasts: can these cells be targeted in anti-cancer therapy?

It is increasingly recognized that the non-neoplastic stromal compartment in most solid cancers plays an active role in tumor proliferation, invasion and metastasis. Cancer-associated fibroblasts (CAFs) are one of the most abundant cell types in the tumor stroma, and these cells are pro-tumorigenic. Evidence that CAFs are epigenetically and possibly also genetically distinct from normal fibroblasts is beginning to define these cells as potential targets of anti-cancer therapy. Here, we review the cell-of-origin and molecular biology of CAFs, arguing that such knowledge provides a rational basis for designing therapeutic strategies to coordinately and synergistically target both the stromal and malignant epithelial component of human cancers.

Global Hypomethylation of Genomic DNA in Cancer-Associated Myofibroblasts

Global hypomethylation has long been recognized as a feature of the malignant epithelial component in human carcinomas. Here we show evidence for this same type of epigenetic alteration in cancer-associated stromal myofibroblasts. We used methylation-sensitive SNP array analysis (MSNP) to profile DNA methylation in early-passage cultures of stromal myofibroblasts isolated from human gastric cancers. The MSNP data indicated widespread hypomethylation in these cells, with rare focal gains of methylation, conclusions that were independently validated by bisulfite sequencing and by a methylation-sensitive cytosine incorporation assay. Immunohistochemistry with anti-5-methylcytosine (anti-5-methyl-C) in a series of gastrectomy specimens showed frequent loss of methylation in nuclei of both the malignant epithelial cells and alpha-smooth muscle actin (ASMA)-positive stromal myofibroblasts of both intestinal-type and diffuse carcinomas. We confirmed this phenomenon and established its onset at the stage of noninvasive dysplastic lesions by immunohistochemistry for anti-5-methyl-C in a transgenic mouse model of multistage gastric carcinogenesis. These findings indicate similar general classes of epigenetic alterations in carcinoma cells and their accompanying reactive stromal cells and add to accumulating evidence for biological differences between normal and cancer-associated myofibroblasts.

Folic Acid Increases Global DNA Methylation and Reduces Inflammation to Prevent Helicobacter-Associated Gastric Cancer in Mice

BACKGROUND & AIMS Previous studies have suggested that dietary folic acid (FA) can protect against certain types of cancers. However, the findings have varied, and the mechanisms by which FA exerts chemopreventive effects remain to be clarified. We examined the effects of FA supplementation on DNA methylation, gene expression, and gastric dysplasia in a transgenic mouse model that is etiologically and histologically well matched with human gastric cancers. METHODS Hypergastrinemic mice infected with Helicobacter felis were studied at multiple stages of gastric dysplasia and early cancer with FA supplementation initiated both at weaning and later in life. Global DNA methylation was assessed by a methylation sensitive cytosine incorporation assay, bisulfite pyrosequencing of B1 repetitive elements, and immunohistochemistry with anti-5-methylcytosine. We also profiled gene expression in the same tissues. RESULTS We found a decrease in global DNA methylation and tissue folate and an increase in serum homocysteine with progression of gastric dysplasia. FA supplementation prevented this loss of global DNA methylation and markedly reduced gastric dysplasia and mucosal inflammation. FA protected against the loss of global DNA methylation both in the dysplastic gastric epithelial cells and in gastric stromal myofibroblasts. In addition, FA supplementation had an anti-inflammatory effect, as indicated by expression profiling and immunohistochemistry for lymphocyte markers. CONCLUSIONS We conclude that FA supplementation is chemopreventive in this model of Helicobacter-associated gastric cancer. The beneficial effect of FA is likely due to its ability to prevent global loss of methylation and suppress inflammation.

Mouse Models of Gastric Cancer

Animal models have greatly enriched our understanding of the molecular mechanisms of numerous types of cancers. Gastric cancer is one of the most common cancers worldwide, with a poor prognosis and high incidence of drug-resistance. However, most inbred strains of mice have proven resistant to gastric carcinogenesis. To establish useful models which mimic human gastric cancer phenotypes, investigators have utilized animals infected with Helicobacter species and treated with carcinogens. In addition, by exploiting genetic engineering, a variety of transgenic and knockout mouse models of gastric cancer have emerged, such as INS-GAS mice and TFF1 knockout mice. Investigators have used the combination of carcinogens and gene alteration to accelerate gastric cancer development, but rarely do mouse models show an aggressive and metastatic gastric cancer phenotype that could be relevant to preclinical studies, which may require more specific targeting of gastric progenitor cells. Here, we review current gastric carcinogenesis mouse models and provide our future perspectives on this field.

ATP11B mediates platinum resistance in ovarian cancer

Platinum compounds display clinical activity against a wide variety of solid tumors; however, resistance to these agents is a major limitation in cancer therapy. Reduced platinum uptake and increased platinum export are examples of resistance mechanisms that limit the extent of DNA damage. Here, we report the discovery and characterization of the role of ATP11B, a P-type ATPase membrane protein, in cisplatin resistance. We found that ATP11B expression was correlated with higher tumor grade in human ovarian cancer samples and with cisplatin resistance in human ovarian cancer cell lines. ATP11B gene silencing restored the sensitivity of ovarian cancer cell lines to cisplatin in vitro. Combined therapy of cisplatin and ATP11B-targeted siRNA significantly decreased cancer growth in mice bearing ovarian tumors derived from cisplatin-sensitive and -resistant cells. In vitro mechanistic studies on cellular platinum content and cisplatin efflux kinetics indicated that ATP11B enhances the export of cisplatin from cells. The colocalization of ATP11B with fluorescent cisplatin and with vesicular trafficking proteins, such as syntaxin-6 (STX6) and vesicular-associated membrane protein 4 (VAMP4), strongly suggests that ATP11B contributes to secretory vesicular transport of cisplatin from Golgi to plasma membrane. In conclusion, inhibition of ATP11B expression could serve as a therapeutic strategy to overcome cisplatin resistance.

A Large Multicenter Experience With Endoscopic Suturing for Management of Gastrointestinal Defects and Stent Anchorage in 122 Patients: A Retrospective Review.

Goals:To describe a multicenter experience using an endoscopic suturing device for management of gastrointestinal (GI) defects and stent anchorage. Background:Endoscopic closure of GI defects including perforations, fistulas, and anastomotic leaks as well as stent anchorage has improved with technological advances. An endoscopic suturing device (OverStitch; Apollo Endosurgery Inc.) has been used. Study:Retrospective study of consecutive patients who underwent endoscopic suturing for management of GI defects and/or stent anchorage were enrolled between March 2012 and January 2014 at multiple academic medical centers. Data regarding demographic information and outcomes including long-term success were collected. Results:One hundred and twenty-two patients (mean age, 52.6 y; 64.2% females) underwent endoscopic suturing at 8 centers for stent anchorage (n=47; 38.5%), fistulas (n=40; 32.7%), leaks (n=15; 12.3%), and perforations (n=20; 16.4%). A total of 44.2% underwent prior therapy and 97.5% achieved technical success. Immediate clinical success was achieved in 79.5%. Long-term clinical success was noted in 78.8% with mean follow-up of 68 days. Clinical success was 91.4% in stent anchorage, 93% in perforations, 80% in fistulas, but only 27% in anastomotic leak closure. Conclusions:Endoscopic suturing for management of GI defects and stent anchoring is safe and efficacious. Stent migration after stent anchoring was reduced compared with published data. Long-term success without further intervention was achieved in the majority of patients. The role of endoscopic suturing for repair of anastomotic leaks remains unclear given limited success in this retrospective study.

Fine‐needle aspirations of pancreatic serous cystadenomas: Improving diagnostic yield with cell blocks and α‐inhibin immunohistochemistry

The diagnosis of serous cystadenoma (SCA), a rare benign pancreatic neoplasm, can alter the management of patients with pancreatic masses. Although characteristic imaging findings and fluid chemical analysis have been described, SCAs are not always recognized preoperatively. Furthermore, scant cellular yield on fine‐needle aspiration (FNA) often leads to a nondiagnostic or nonspecific benign diagnosis. α‐Inhibin (AI), a sensitive marker for SCA, is infrequently required for diagnosis in surgical specimens due to their characteristic histologic appearance. The objective of the current study was to determine whether AI staining can improve SCA diagnosis on FNA specimens.

Fully covered self-expandable metal stents for benign esophageal disease: a multicenter retrospective case series of 31 patients

failure to thrive, aspiration causing recurrent pneumonia, upper respiratory tract infection, and food or foreign-body impaction.7,8 Esophagography was the primary diagnostic tool and was performed in all patients (Fig. 5). The esophagography results showed segmental stenosis at the distal third of the esophagus in all patients except 1. Esophagoscopy was performed in most patients and usually showed a nonspecific distal esophageal stenosis without inflammation. Repeated dilation of the stricture was performed in 33 patients, resulting in only transient or no relief of dysphagia. Three patients had esophageal perforation after dilation, with 1 death after a single dilation. In most of the patients, definitive treatment was performed between 1 and 3 months of age, and surgical resection was required. The diagnosis of TBRs (57 patients) could only be made by histopathological examination of the resected segment, thus underscoring the importance of EUS in the preoperative diagnosis of TBRs.

Early Detection of Pancreatic Cancer

Despite treatment advances pancreatic cancer remains one of the most lethal malignancies. It is expected that early detection and screening of high risk patient population may have the most significant impact on altering overall survival in this disease. Serologic biomarkers may be the most useful in early detection and histology-based markers may have the most significant role in differentiating benign, pre-malignant and malignant lesions. Here we review several serum and tissue-based biomarkers and summarize new data presented at the 2012 ASCO Gastrointestinal Cancers Symposium (Abstracts #151, #164, #188) on the potential role of PAM4 in pancreatic cancer screening and diagnosis.