Development of solid cancer depends on escape from host immunosurveillance. Various types of immune cells contribute to tumor‐induced immune suppression, including tumor associated macrophages, regulatory T cells, type 2 NKT cells, and myeloid‐derived suppressor cells (MDSCs). Growing body of evidences shows that MDSCs play pivotal roles among these immunosuppressive cells in multiple steps of cancer progression. MDSCs are immature myeloid cells that arise from myeloid progenitor cells and comprise a heterogeneous immune cell population. MDSCs are characterized by the ability to suppress both adaptive and innate immunities mainly through direct inhibition of the cytotoxic functions of T cells and NK cells. In clinical settings, the number of circulating MDSCs is associated with clinical stages and response to treatment in several cancers. Moreover, MDSCs are reported to contribute to chemoresistant phenotype. Collectively, targeting MDSCs could potentially provide a rationale for novel treatment strategies in cancer. This review summarizes recent understandings of MDSCs in cancer and discusses promissing clinical approaches in cancer patients.

HIG2 (hypoxia-inducible gene 2) is a biomarker of hypoxia and elevated in several cancers. Here, we show that HIG2 also upregulated HIF-1α expression under hypoxic conditions and enhanced AP-1 expression under normoxic conditions, which affects colorectal cancer cell survival. Importantly, over-expression of HIG2 promoted tumor growth by suppressing apoptosis in a mouse orthotopic model. These results are likely relevant to human disease since we found that the expression of HIG2 is gradually elevated as tumors progress. Collectively, these findings suggest that HIG2 plays an important role in promoting colorectal cancer growth in hypoxia-dependent and independent manners.

Methylation of cysteine dioxygenase type 1 (CDO1) gene, a tumor suppressor gene, has been studied in various cancers; however, there is no information regarding Barrett esophagus cancer. In this study, the clinical significance of CDO1 methylation in Barrett esophagus adenocarcinoma (BEA) was clarified. CDO1 gene promoter methylation was analyzed for DNA from the patient's specimens using quantitative methylation-specific polymerase chain reaction. Thirty-eight BEA patients who underwent resection were identified between 2000 and 2014. Hypermethylation of CDO1 gene was demonstrated to be frequently recognized even at early stage in BEA by quantitative methylation-specific polymerase chain reaction. In BEA, there is a robust prognostic difference between stage I and stage II/III/IV with regard to 5-year relapse-free survival (P = 0.0016) and 5-year overall survival (P = 0.0024), and the tumor size separated by 7 cm was also a prognostic factor. There was significant difference in CDO1 gene methylation according to the tumor size (P = 0.036). BEA patients with CDO1 gene methylation were shown marginally significantly poorer prognosis (P = 0.054) than otherwise patients. In conclusion, higher CDO1 gene methylation was seen in BEA at earlier stage than in squamous cell carcinoma, and it may account for aggressive phenotype of BEA.