Tehran University Medical Journal

Breast carcinoma is the most common cause of cancer mortality among women globally. Primary and secondary prevention through avoiding known risk factors, screening for early detection of tumors with different methods as well as timely treatment, can be effective in reduction of the burden of this devastating disease. This can in turn prevent death and also increase survival in patients with breast cancer. Both environmental and genetic factors are involved in the pathogenesis of breast cancer. Multiple genetic factors can influence the risk and development of breast cancer. Identification of genetic variants including single nucleotide polymorphisms (SNPs), which are associated with the risk of breast cancer development, are mostly done through genetic association studies. It is demonstrated that SNP allele frequencies vary amongst different populations. It has been shown that genetic risk factors like variations in TOX high mobility group box family member 3 (TOX3), which affect the liability for neoplasm, play an important role in the development of breast cancer. Although TOX3 is expressed mainly in the brain, its expression in other tissues especially breast has also been reported. TOX3 maps to chromosome 16q12 and encodes the nuclear high-mobility group (HMG)-box. It has calcium (Ca²⁺)-dependent transcriptional activities and is a co-factor of cAMP response element (CRE)-binding protein (CREB) and CREB-binding protein (CBP). TOX3, activated with Ca²⁺, is related with activation of the promoter of some other genes including BCL2 and C3 complement and also CITED1 gene expression. It also induces activation of the c-fos promoter and therefore its expression. Genome-wide association studies (GWAS) in different populations including European, Asian and African-American have demonstrated that a SNP near its 5ʹ end and the promoter of TOX3 gene appears to be significantly associated with breast cancer susceptibility. Furthermore, breast cancer–associated SNPs lead to enhanced FOXA1 bindings and in turn, a reduction in TOX3 gene expression. This review has highlighted the importance of TOX3 function, SNPs and its association with breast cancer risk and also its potential effects on breast cancer treatment; TOX3 plays dual and somehow conflicting roles in cancer initiation and progression which remains to be further investigated.

Gastric cancer (GC) is the second leading cause of cancer-related deaths worldwide. It has been proposed that the specific genotypes of Helicobacter pylori (H. pylori) are the causative agents in the development of gastroduodenal diseases, such as chronic atrophic gastritis, peptic ulcerations, and GC. However, disease progression to GC occurs in only a small proportion of infected patients. Recently, we identified a novel polymorphic site in the 3ʹ-end region of H. pylori vacA gene. The vacA c1 genotype increased the risk of GC. This association was independent of and larger than the associations of the m-, i-, and d-type of vacA or cagA status with GC. Therefore, treatment of H. pylori infection may be an effective way to prevent GC. Expression of cytokines and their associations with inflammatory responses has been shown. Several cytokine polymorphisms, such as IL-1B, IL-8, IL-10, and TNF-α have been considered as risk factors for GC. It has been shown that the interaction of bacterial genotypes and host factors plays an essential role in developing GC. Several altered molecular pathways are involved in the pathogenesis of GC. Micro-RNAs are small, non-coding RNAs of 18-25 nucleotides in length that regulate the expression of target mRNAs. Expression pattern of cancer cells is different compared with the normal cells. Micro-RNAs plays a critical role in apoptosis and classified in two groups: pro- and anti-apoptotic agents. Recent studies have confirmed the oncogenic or tumor suppression role of micro-RNAs in cancer cells. They play a significant role in the GC cell physiology and tumor progression, by translational suppression of target genes. These small RNAs have therefore emerged as a new type of GC biomarker with immeasurable clinical potential. Generally, a variety of micro-RNAs involved in different stages of cancer, including tumorigenesis, angiogenesis, and metastasis. Considering to this issue more than 50% of cancers can be cured, if they were diagnosed in the early stages. Hence, identifying the biomarkers of GC could play an important role in prevention, early diagnosis and rapid treatment of patients. In this review article, we have reviewed the latest findings about bacterial and tissue biomarkers of GC