Chronic infection of Mycoplasma hyorhinis (M. hyorhinis) has been postulated to be associated with several types of cancer, but its effect on patients’ survival and host factors mediating its infection remain unclear. Herein, we demonstrated that M. hyorhinis p37 protein expression in gastric cancer tissues predicts poor survival and associates with metastasis. M. hyorhinis infects mammalian cells and promotes gastric cancer cell invasiveness via its membrane protein p37. Synthesized peptide corresponding to the N-terminus of p37 prevents M. hyorhinis infection. Host Annexin A2 (ANXA2) interacts with the N-terminus of p37. In addition, EGFR forms a complex with p37 and ANXA2, and is required for M. hyorhinis–induced phosphorylation and membrane recruitment of ANXA2. M. hyorhinis infection is inhibited by siRNA-mediated knockdown of ANXA2 or EGFR, but is enhanced by expression of ectopic ANXA2 or EGFR. Downstream of ANXA2 and EGFR, the NF-κB pathway is activated and mediates M. hyorhinis–driven cell migration. In conclusion, our study unveils the effect of M. hyorhinis infection on gastric cancer survival and uncovers the mechanisms by which M. hyorhinis infects mammalian cells and promotes cancer cell migration. Cancer Res; 74(20); 1–13. ©2014 AACR.

Chronic infection of Mycoplasma hyorhinis (M. hyorhinis) has been postulated to be associated with several types of cancer, but its effect on patients’ survival and host factors mediating its infection remain unclear. Herein, we demonstrated that M. hyorhinis p37 protein expression in gastric cancer tissues predicts poor survival and associates with metastasis. M. hyorhinis infects mammalian cells and promotes gastric cancer cell invasiveness via its membrane protein p37. Synthesized peptide corresponding to the N-terminal of p37 prevents M. hyorhinis infection. Host Annexin A2 (ANXA2) interacts with the N-terminal of p37. In addition, EGFR forms complex with p37 and ANXA2, and is required for M. hyorhinis-induced phosphorylation and membrane recruitment of ANXA2. M. hyorhinis infection is inhibited by siRNA-mediated knockdown of ANXA2 or EGFR, but is enhanced by expression of ectopic ANXA2 or EGFR. Downstream of ANXA2 and EGFR, NF-κB pathway is activated and mediates M. hyorhinis-driven cell migration. In conclusion, our study unveils the effect of M. hyorhinis infection on gastric cancer survival and uncovers the mechanisms by which M. hyorhinis infects mammalian cells and promotes cancer cell migration.

Epithelial-to-mesenchymal transition (EMT) enables metastasis. E-cadherin loss is a hallmark of EMT, but there remains an incomplete understanding of the epigenetics of this process. The protein arginine methyltransferase PRMT7 functions in various physiologic processes, including mRNA splicing, DNA repair, and neural differentiation, but its possible roles in cancer and metastasis have not been explored. In this report, we show that PRMT7 is expressed at higher levels in breast carcinoma cells and that elevated PRMT7 mediates EMT and metastasis. PRMT7 could inhibit the expression of E-cadherin by binding to its proximal promoter in a manner associated with altered histone methylation, specifically with elevated H4R3me2s and reduced H3K4me3, H3Ac, and H4Ac, which occurred at the E-cadherin promoter upon EMT induction. Moreover, PRMT7 interacted with YY1 and HDAC3 and was essential to link these proteins to the E-cadherin promoter. Silencing PRMT7 restored E-cadherin expression by repressing H4R3me2s and by increasing H3K4me3 and H4Ac, attenuating cell migration and invasion in MDA-MB-231 breast cancer cells. Overall, our results define PRMT7 as an inducer of breast cancer metastasis and present the opportunity for applying PRMT7-targeted therapeutics to treat highly invasive breast cancers. Cancer Res; 74(19); 1–12. ©2014 AACR.

Some retrospective studies suggest an association between infection with GB virus-C (GBV-C) and non-Hodgkin lymphoma (NHL). We evaluated this association prospectively in a nested case–control study within the U.S. Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. Cases (N = 658) and controls (N = 1,316) were individually matched by age, sex, race/ethnicity, timing of study entry, and sample selection. Prediagnostic PLCO serum samples were tested for GBV-C RNA (as a measure of active infection) and E2 antibody (active or resolved infection). Logistic regression was used to estimate odds ratios (OR) for the association between GBV-C and NHL overall and NHL subtypes. Twelve cases (1.8%) and seven controls (0.5%) were GBV-C RNA-positive. GBV-C RNA positivity was associated with NHL overall [OR, 3.43; 95% confidence interval (CI), 1.35–8.71] and, based on small numbers, diffuse large B-cell lymphoma (OR, 5.31; 95% CI, 1.54–18.36). The association with NHL persisted when the interval between testing and selection was greater than 4 years (OR, 6.00; 95% CI, 1.21–29.73). In contrast, E2 antibody positivity was not associated with NHL risk (OR, 1.08; 95% CI, 0.74–1.58). Our study demonstrates that GBV-C infection precedes development of NHL. GBV-C infection may play an etiologic role in a small proportion of NHL cases, perhaps by causing chronic immune stimulation or impaired immunosurveillance. Cancer Res; 74(19); 1–8. ©2014 AACR.

DNA repair processes are a key determinant of the sensitivity of cancer cells to DNA-damaging chemotherapeutics, which may induce certain repair genes as a mechanism to promote resistance. Here, we report the results of a screen for repair genes induced in cancer cells treated with DNA crosslinking agents, which identified the translesion polymerase η (PolH) as a p53-regulated target acting as one defense against interstrand crosslink (ICL)-inducing agents. PolH was induced by fotemustine, mafosfamide, and lomustine in breast cancer, glioma, and melanoma cells in vitro and in vivo, with similar inductions observed in normal cells such as lymphocytes and diploid fibroblasts. PolH contributions to the protection against ICL-inducing agents were evaluated by its siRNA-mediated attenuation in cells, which elevated sensitivity to these drugs in all tumor cell models. Conversely, PolH overexpression protected cancer cells against these drugs. PolH attenuation reduced repair of ICL lesions as measured by host cell reactivation assays and enhanced persistence of γH2AX foci. Moreover, we observed a strong accumulation of PolH in the nucleus of drug-treated cells along with direct binding to damaged DNA. Taken together, our findings implicated PolH in ICL repair as a mechanism of cancer drug resistance and normal tissue protection. Cancer Res; 74(19); 1–12. ©2014 AACR.