Human papillomavirus promotes esophageal squamous cell carcinoma by regulating DNA methylation and expression of HLA-DQB1

Viral Infection in Esophageal, Gastric, and Colorectal Cancer

The human gastrointestinal tract, which constitutes the digestive system, contains a large number of virus particles that maintain organizational homeostasis and health. Conversely, viral pathogens have also attracted attention for their involvement in the pathogenesis of certain cancers, including gastrointestinal cancers. To aid prevention and treatment of these cancers, the relevance of gastrointestinal viral factors as potential risk factors needs to be carefully investigated. This review summarizes and discusses the available literature on the relationship between the development of esophageal, gastric, and colorectal cancers and their corresponding viruses. This review reveals that research on the association between colorectal cancer and viruses, in particular, is still in its infancy compared to the association between HPV and esophageal cancer and between EBV and gastric cancer.

Viruses in Cancers of the Digestive System: Active Contributors or Idle Bystanders?

The human virome, which is a collection of all the viruses that are present in the human body, is increasingly being recognized as an essential part of the human microbiota. The human gastrointestinal tract and related organs (e.g., liver, pancreas, and gallbladder)-composing the gastrointestinal (or digestive) system-contain a huge number of viral particles which contribute to maintaining tissue homeostasis and keeping our body healthy. However, perturbations of the virome steady-state may, both directly and indirectly, ignite/sustain oncogenic mechanisms contributing to the initiation of a dysplastic process and/or cancer progression. In this review, we summarize and discuss the available evidence on the association and role of viruses in the development of cancers of the digestive system.

A viral map of gastrointestinal cancers

Cancers of the gastrointestinal tract (GIT) are expected to account for approximately 20% of all cancers in 2017. Apart from their high incidence, GIT cancers show high mortality rates, placing these malignancies among the most prominent public health issues of our time. Cancers of the GIT are the result of a complex interplay between host genetic factors and environmental factors and frequently arise in the context of a continued active inflammatory response. Several tumor viruses are able to elicit such chronic inflammatory responses. In fact, several viruses have an impact on GIT tumor initiation and progression, as well as on patients' response to therapy and prognosis, through direct and indirect mechanisms. In this review, we have gathered information on different viruses' rates of infection, viral-driven specific carcinogenesis mechanisms and viral-related impact on the prognosis of cancers of the GIT (specifically in organs that have an interface with the environment - esophagus, stomach, intestines and anus). Overall, while some viral infections show a strong causal relation with specific gastrointestinal cancers, these represent a relatively small fraction of GIT malignancies. Other types of cancer, like Esophageal Squamous Cell Carcinoma, require further studies to confirm the carcinogenic role of some viral agents.

Association of human papillomavirus type 58 with breast cancer in Shaanxi province of China

A number of reports have identified HPV DNA in breast cancer specimens and HPV type 16, 18, 31, 33, 45, and 51 were more prevalent. HPV 58 was frequently detected in cervical cancer in Shaanxi China. The aim of the present study was to investigate whether HPV 58 present in breast cancer. 169 cases of breast cancer samples and 83 benign breast lesions were analyzed. Type specific primers and oligonucliotide probe were used for the detection of HPV 58 by conventional PCR and in situ hybridization techniques. The HPV 58 viral load were measured by qPCR. p16 protein expression were evaluated by immunohistochemistry. HPV 58 E7 DNA was detected in 25 out of 169 formalin fixed paraffin embedded breast cancer tissues (14.79%) by PCR, only 1 out of 83 non-malignant breast lesions showed positive (1.20%). The results of ISH showed that 17 out of 169 (10.06%) malignant samples were positive for HPV 58 E7, and only 1 out of 83 non-malignant lesions was positive. Positive p16 immunostaining was observed in all the HPV 58 E7 ISH positive cases, but 16 out of 98 cases with HPV negative were p16 positive. The presence of HPV 58 in both normal duct epithelial cells and carcinoma in situ along with its presence in the cancer cells of the same specimen indicated the possible causal role of HPV 58 in breast cancer. The findings provide a solid morphological evidence of the involvement of HPV 58 in breast cancer development.