Epstein-Barr virus is seldom found in mammary epithelium of breast cancer tissue using in situ molecular methods

Is EBV Associated with Breast Cancer in Specific Geographic Locations?

Epstein-Barr virus (EBV) is a virus that establishes a life-long infection in people, and infection with EBV is nearly ubiquitous by adulthood. EBV was identified from biopsy material from a child with Burkitt's lymphoma (BL) in sub-Saharan Africa. EBV has a well-characterised role in the development of some cancers, notably, Burkitt's lymphoma (BL), Hodgkin's disease (HD), gastric carcinoma (GC), and nasopharyngeal carcinoma (NPC). Links have also been made between EBV and breast cancer (BC), but these have been controversial. For all EBV-associated cancers, the ubiquitous nature of infection with EBV, contrasted with the relatively rare development of cancer, highlights a problem of determining whether EBV is an aetiological agent of cancer. In addition, the geographic distributions of some EBV-associated cancers point to contributions from additional co-factors. Recent meta-analyses of the incidence of EBV within BC biopsies has revealed that the diversity in the conclusions remain, however, they also show more of an association between EBV and BC biopsies in some study locations. Here, we review the evidence linking EBV with BC, and conclude that the evidence for the presence of EBV in BC biopsies is concentrated in specific geographic regions but is currently insufficient to provide a causal link. We pose some questions that could help to resolve the question of whether EBV contributes to BC and probe the contribution EBV might make to the aetiology of BC.

Epstein-Barr virus and risk of breast cancer: a systematic review and meta-analysis

Despite the numerous publications regarding the role of Epstein-Barr virus (EBV) in breast cancer development, the topic has still remained controversial. The aim of the meta-analysis was to estimate the overall prevalence of EBV in the breast cancer population, and to investigate the association between EBV and breast cancer risk. The overall prevalence of EBV was calculated 26.37% (95% CI: 22-31%) from the 44 included studies. Meta-analysis of 30 case-control studies showed that the pooled association between EBV and risk of breast cancer is odds ratio 4.74 (95% CI: 2.92-7.69; Z = 6.30; p < 0.0001). Our analyses indicate a strong statistical relationship between EBV infection and risk of breast cancer, suggesting a potential role of EBV infection in the development of breast cancer.

Viral infections and breast cancer - A current perspective

Sporadic human breast cancer is the most common cancer to afflict women. Since the discovery, decades ago, of the oncogenic mouse mammary tumour virus, there has been significant interest in the potential aetiologic role of infectious agents in sporadic human breast cancer. To address this, many studies have examined the presence of viruses (e.g. papillomaviruses, herpes viruses and retroviruses), endogenous retroviruses and more recently, microbes, as a means of implicating them in the aetiology of human breast cancer. Such studies have generated conflicting experimental and clinical reports of the role of infection in breast cancer. This review evaluates the current evidence for a productive oncogenic viral infection in human breast cancer, with a focus on the integration of sensitive and specific next generation sequencing technologies with pathogen discovery. Collectively, the majority of the recent literature using the more powerful next generation sequencing technologies fail to support an oncogenic viral infection being involved in disease causality in breast cancer. In balance, the weight of the current experimental evidence supports the conclusion that viral infection is unlikely to play a significant role in the aetiology of breast cancer.

Evidence for the association of Epstein-Barr Virus in breast cancer in Indian patients using in-situ hybridization technique

Epstein-Barr Virus (EBV) is etiologically linked to Burkitt lymphoma (BL), nasopharyngeal carcinoma, post-transplant lymphomas, Hodgkin disease, and possibly other tumors. However, the association of oncogenic EBV with breast carcinoma (BC) is still controversial and a matter of debate. We aimed to study the presence of EBV genome in BC cases in Indian patients and its association with the clinicopathological features. The formalin fixed paraffin embedded tissues from 83 women with primary invasive BC were studied for the presence of EBV by in-situ hybridization (ISH) technique for Epstein-Barr Virus Encoded RNA (EBER) with appropriate controls. Correlation of EBER-ISH positivity with clinicopathological features was performed using Fisher exact test and P<.05 was considered as significant. Eighty-three BC cases were comprised of 47 (56.5%) triple negative breast cancers (TNBC), 17 (20.5%) hormone positive and 19 (22.9%) HER2 positive cases. Of 83 cases, 25 cases (30.1%) were positive for EBER-ISH test. The positivity was restricted to the tumor cells and not seen in the surrounding breast lobules. EBER-ISH positivity was statistically associated with larger tumor size (52.6% in >5 cm tumors vs 19.3% in ≤5 cm; P=.014) and with TNBCs (21/47 [44.7%] in TNBCs vs 4/36 [11.1%] in non-TNBCs; P=.001). A possible causal association of EBV in BC cases in Indian patients is suggested by high frequency of EBER-ISH positivity noted in our study. This might have therapeutic significance because of the possible role of EBV specific cytotoxic T cells in targeting EBV associated tumor cells and can be considered as a potential targeted therapy. To the best of our knowledge, this is the first study from India to address this issue using EBER-ISH technique.

Evaluation Frequency of Merkel Cell Polyoma, Epstein-Barr and Mouse Mammary Tumor Viruses in Patients with Breast Cancer in Kerman, Southeast of Iran

Breast cancer is the most common cancer among women worldwide. Roles of the Epstein-Barr, Merkel cell polyoma and mouse mammary tumor viruses in breast carcinogenesis are still controversial although any relationship would clearly be important for breast cancer etiology, early detection and prevention. In the present study associations between EBV, MMTV and Merkel cell polyoma virus and breast cancer in 100 Iranian patients were evaluated using paraffin-embedded tissues. EBER RNA and expression of p53 and large T antigen were evaluated by real time PCR and CD34, p63, HER2, PR and ER markers were studied by immunohistochemistry. EBV was detected in 8/100 (8%), MMTV in 12/100 (12%), MPy in 3/100 (3%) and EBER RNA in 18/100 (18%) cases. None of the control samples demonstrated any of the viruses. p53 was suppressed in EBV, MPy and MMTV positive samples. The large T antigen rate was raised in MPy positive samples. Our results showed that EBV, MMTV and the Merkel cell polyoma virus are foundwith some proportion of breast cancers in our patients, suggesting that these viruses might have a significant role in breast cancer in Kerman, southeast of Iran.

Specific Neuropilins Expression in Alveolar Macrophages among Tissue-Specific Macrophages

In the immune system, neuropilins (NRPs), including NRP-1 and NRP-2, are expressed in thymocytes, dendritic cells, regulatory T cells and macrophages. Their functions on immune cells around the neoplastic cells vary into pro-angiogenesis, tumor progression and anti-angiogenesis according to their ligands. Even though NRPs expression on malignant tumors and immune system has studied, a PubMed-based literature query did not yield any articles describing NRPs expression on tissue-specific macrophages. The aims of this study were (i) to detect NRPs expression on tissue-specific macrophages in the brain, liver, spleen, lymph node and lung; (ii) to observe NRPs expression in classes of macrophages, including alveolar macrophages (AMs), bronchial macrophages (BMs), interstitial macrophages (IMs), intravascular macrophages (IVMs) and macrophage subsets (M1, M2 and Mox) in lung; and (iii) to detect the co-expression of NRPs and dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN) in AMs. Both NRPs were specifically detected in AMs among tissue-specific macrophages by immunohistochemistry (IHC). NRPs mRNA expression levels were characterized in normal lung by reverse transcriptase polymerase chain reaction (RT-PCR) and in situ-polymerase chain reaction (in situ-PCR). The expression of both NRPs was detected in AMs, BMs and IVMs by IHC. The frequency of NRPs⁺ AMs in lung tissue adjacent to the cancer margin was significantly higher than the frequencies in inflamed and normal lung tissue. Double and triple IHC demonstrated that NRPs are expressed on all macrophage subsets in lung. Double IHC showed co-expression of DC-SIGN and NRPs in AMs. This study demonstrated for the first time the specific expression of both NRPs in AMs among tissue-specific macrophages and their expression on M1, M2 and Mox macrophages. Furthermore, the possible origin of AMs from blood monocytes could be suggested from a co-expression of NRPs and DC-SIGN.

Cytomegalovirus and Epstein-Barr virus in breast cancer

Findings of polymerase chain reaction (PCR) studies of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) and breast cancer vary, making it difficult to determine whether either, both, or neither virus is causally associated with breast cancer. We investigated CMV and EBV in paired samples of breast cancer and normal breast tissue from 70 women using quantitative PCR. A serum sample from each woman was tested for CMV and EBV IgG. To place our results in context, we reviewed the existing literature and performed a meta-analysis of our results together with previous PCR studies of EBV, CMV, and breast cancer. Of the serology samples, 67 of 70 (96%) were EBV IgG positive and 49 of 70 (70%) were CMV IgG positive. QPCR detected EBV in 24 (34%) of the tumour and 9 (13%) of the paired normal specimens and CMV in 0 (0%) of the tumour and 2 (3%) of the paired normal specimens. Our findings, together with earlier results summarised in the meta-analysis, suggest several possibilities: variable findings may be due to limitations of molecular analyses; 'hit and run' oncogenesis may lead to inconsistent results; one or both viruses has a role at a later stage in breast cancer development; infection with multiple viruses increases breast cancer risk; or neither virus has a role. Future studies should focus on ways to investigate these possibilities, and should include comparisons of breast cancer tissue samples with appropriate normal tissue samples.

Association of Epstein-Barr virus with invasive breast carcinoma and its impact on well-known clinicopathologic parameters in Iranian women

Background:

The association between Epstein-Barr virus (EBV) and breast carcinoma in Iranian women is uncertain. We examined EBV latent membrane protein-1 (LMP-1) antigen expression in breast carcinoma and its relationship with clinicopathologic parameters among a population of Iranian patients.

Materials and Methods:

This study was performed on formalin fixed and paraffin embedded tissue specimens with a diagnosis of invasive breast carcinoma archived at one university hospital in Isfahan city, Iran. We used immunohistochemistry to detect LMP-1 of EBV in carcinoma and its adjacent normal tissue. The frequency of LMP-1 expression in breast carcinoma and its relationship with age, tumor size, tumor type, tumor grade and lymph node status were then determined.

Results:

A total of 80 cases were evaluated including 77 (96.3%) ductal, 1 (1.3%) lobular, 1 (1.3%) medullary and 1 (1.3%) mucinous carcinoma. LMP-1 expression was seen in 6 cases (7.5%) of breast carcinoma whereas normal breast tissue adjacent to carcinoma was negative for LMP-1 in all of the cases. A statistically significant association was seen between EBV and invasive breast carcinoma (P = 0.03). No significant relationship was observed between LMP-1 expression on one hand and age, tumor size, tumor type, tumor grade and lymph node status on the other.

Conclusion:

EBV may play an etiological role in some of the cases of breast carcinoma in Iranian women. EBV expression does not seem to have a significant impact on the major clinicopathologic prognostic determinants of breast carcinoma.

An expanded myeloid derived suppressor cell population does not play a role in gammaherpesvirus-exacerbated breast cancer metastases

Background

Mice latently infected with murine gammaherpesvirus 68 (HV-68) and transplanted with 4 T1 breast cancer cells developed exacerbated metastatic lesions when compared to controls. The mechanisms responsible for this viral-exacerbated disease were not clear. The ability of HV-68 infection to induce S100A8 and S100A9 production and to expand a population of CD11b+Gr-1+ cells suggested that increased numbers, or activity, of viral-expanded myeloid derived suppressor cells (MDSCs) might contribute to HV-68-associated metastatic breast cancer in this model. We questioned whether mock or HV-68 infected mice with significant breast cancer might have differences in the number and/or activity of MDSCs.

Methods

Myeloid-derived macrophages and dendritic cells were isolated from normal mice and cultured in vitro with HV-68 to assess S100A8 and S100A9 mRNA and protein expression. In vivo studies were performed using groups of mice that were mock treated or infected with HV-68. After viral latency was established, 4 T1 breast cancer cells were transplanted in mice. When primary breast tumors were present mice were euthanized and cells isolated for phenotyping of myeloid cell populations using FACS, and for ex vivo analysis of suppressor activity. Serum from these animals was also collected to quantify S100A8 and S100A9 levels.

Results

In vitro studies demonstrated that direct exposure of myeloid cells to HV-68 did not induce increased expression of S100A8 or S100A9 mRNAs or secreted protein. HV-68 infected mice with metastatic breast cancer disease had no increases in S100A8/A9 levels and no significant increases in the numbers or activation of CD11b+Gr-1+MDSCs when compared to mock treated mice with breast cancer.

Conclusions

Together these studies are consistent with the notion that expanded myeloid derived suppressor cells do not play a role in gammaherpesvirus-exacerbated breast cancer metastases. The mechanisms responsible for HV-68 induced exacerbation of metastatic breast cancer remain unclear.

Exacerbated metastatic disease in a mouse mammary tumor model following latent gammaherpesvirus infection

Background

Controversy exists as to the ability of human gammaherpesviruses to cause or exacerbate breast cancer disease in patients. The difficulty in conducting definitive human studies can be overcome by investigating developing breast cancer in a mouse model. In this study, we utilized mice latently infected with murine gammaherpesvirus 68 (HV-68) to question whether such a viral burden could exacerbate metastatic breast cancer disease using a mouse mammary tumor model.

Results

Mice latently infected with HV-68 had a similar primary tumor burden, but much greater metastatic disease, when compared to mock treated mice given the transplantable tumor, 4 T1. This was true for lung lesions, as well as secondary tumor masses. Increased expression of pan-cytokeratin and VEGF-A in tumors from HV-68 infected mice was consistent with increased metastatic disease in these animals. Surprisingly, no viral particles could be cultured from tumor tissues, and the presence of viral DNA or RNA transcripts could not be detected in primary or secondary tumor tissues.

Conclusions

Latent HV-68 infection had no significant effect on the size of primary 4 T1 mammary tumors, but exacerbated the number of metastatic lung lesions and secondary tumors when compared to mock treated mice. Increased expression of the tumor marker, pan-cytokeratin, and VEGF-A in tumors of mice harboring latent virus was consistent with an exacerbated metastatic disease. Mechanisms responsible for this exacerbation are indirect, since no virus could be detected in cancerous tissues.