Myeloid-derived suppressor cells (MDSCs) are a group of heterogeneous cells which are abnormally accumulated during the differentiation of myeloid cells. Immunosuppression is the main functional feature of MDSCs, which inhibit T cell activity in the tumor microenvironment (TME) and promote tumoral immune escape. The main principle for immunotherapy is to modulate, restore, and remodel the plasticity and potential of immune system to have an effective anti-tumor response. In the TME, MDSCs are major obstacles to cancer immunotherapy through reducing the anti-tumor efficacy and making tumor cells more resistant to immunotherapy. Therefore, targeting MDSCs treatment becomes the priority of relevant studies and provides new immunotherapeutic strategy for cancer treatment. In this review, we mainly discuss the functions and mechanisms of MDSCs as well as their functional changes in the TME. Further, we review therapeutic effects of immunotherapy against MDSCs and potential breakthroughs regarding immunotherapy targeting MDSCs and immune checkpoint blockade (ICB) immunotherapy.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that accumulate in tumor-bearing hosts to reduce T cells activity and promote tumor immune escape in the tumor microenvironment (TME). The immune system in the TME can be stimulated to elicit an anti-tumor immune response through immunotherapy. The main theory of immunotherapy resides on the plasticity of the immune system and its capacity to be re-educated into a potent anti-tumor response. Thus, MDSCs within the TME became one of the major targets to improve the efficacy of tumor immunotherapy, and therapeutic strategies for tumor MDSCs were developed in the last few years. In the article, we analyzed the function of tumor MDSCs and the regulatory mechanisms of agents targeting MDSCs in tumor immunotherapy, and reviewed their therapeutic effects in MDSCs within the TME. Those data focused on discussing how to promote the differentiation and maturation of MDSCs, reduce the accumulation and expansion of MDSCs, and inhibit the function, migration and recruitment of MDSCs, further preventing the growth, invasion and metastasis of tumor. Those investigations may provide new directions for cancer therapy.

AIM: To investigate the effect and significance of selenium in early experimental gastric carcinogenesis. METHODS: Weaning male Wistar rats were divided randomly into normal control group, experiment control group, low selenium (2 mg/L) group and high selenium (4 mg/L) group. Wistar rat gastric carcinogenesis was induced by N-methyl-N-nitro-N-nitroso guanidine (MNNG) (20 mg/kg) gavage daily for 10 d. Na₂SeO₃ was given by piped drinking 1 wk prior to MNNG gavage. The rats were killed at the 43^rd wk. The surface characteristics of gastric mucosa were observed with naked eyes. Histopathologic changes of rat gastric mucosa were observed by HE staining and AB-PAS methods. The changes of cellular ultrastructure were observed under transmission electron microscope. Statistical analysis was carried out by SPSS. RESULTS: The incidence rate of gastric mucosa erosion, hemorrhage and intestinal metaplasia was 0, 45.5%, 66.7%, and 92.9%, respectively (92.9% vs 45.5%, P<0.05) in the normal control group, experiment control group, low selenium group, and high selenium group. Leiomyoma formed in the process of inducement of rat gastric carcinoma. Dietary Na₂SeO₃ (2 and 4 mg/L) slightly increased the incidence rate of leiomyoma (0, 23%, 46.6%, and 46.6%). gastric mucosa did not change in the course of rat gastric carcinogenesis. Dietary Na₂SeO₃ by pipe drinking could expand the intracellular secretory canaliculus of parietal cells and increase the number of endocrine cells and lysosomes. CONCLUSION: Dietary Na₂SeO₃ by pipe drinking aggravates gastric erosion, hemorrhage and promotes intestinal metaplasia of gastric mucosa. The mechanism may be related with the function of parietal cells.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of immature cells derived from bone marrow that play critical immunosuppressive functions in the tumor microenvironment (TME), promoting cancer progression. According to base length, Non-coding RNAs (ncRNAs) are mainly divided into: microRNAs (miRNAs), lncRNAs, snRNAs and CircRNAs. Both miRNA and lncRNA are transcribed by RNA polymerase II, and they play an important role in gene expression under both physiological and pathological conditions. The increasing data have shown that MiRNAs/LncRNAs regulate MDSCs within TME, becoming one of potential breakthrough points at the investigation and treatment of cancer. Therefore, we summarize how miRNAs/lncRNAs mediate the differentiation, expansion and immunosuppressive function of tumor MDSCs in TME. We will then focus on the regulatory mechanisms of exosomal MicroRNAs/LncRNAs on tumor MDSCs. Finally, we will discuss how the interaction of miRNAs/lncRNAs modulates tumor MDSCs.

The liver plays a crucrial role in detoxification, metabolism, and nutrient storage. Because liver cancer ranks among the top three leading causes of death globally, there is an urgent need for developing treatment strategies for liver cancer. Although traditional approaches such as radiation, chemotherapy, surgical removal, and transplantation are widely practiced, the number of patients with liver cancer continues to increase rapidly each year. Some novel therapeutics for liver cancer have been studied for many years. In the past decade, oncolytic therapy has emerged, in which viruses selectively infect and destroy cancer cells while sparing normal cells. However, oncolytic virotherapy for liver cancer remains relatively obscure due to the aggressive nature of the disease and the limited effectiveness of treatment. To keep pace with the latest developments in oncolytic tumor therapy for liver cancer, this review summarizes basic science studies and clinical trials conducted within 5 years, focusing on the efficacy and safety profiles of the five most commonly used oncolytic viruses: herpes simplex virus, adenovirus, influenza virus, vaccinia virus, and coxsackievirus.

Purpose The purpose of this study is to explore whether the down-regulation of ALOX15 is related to the stage, differentiation and prognosis of lung adenocarcinoma, whether the overexpression of ALOX15 can inhibit tumor proliferation and metastasis, and whether it is related to the functional target of lung adenocarcinoma(LUAD). Methods Firstly, bioinformatics of lung cancer patients was analyzed using the TCGA database to study the differential expression of ALOX15 in LUAD and its effect on the survival of LUAD. Then, 50 clinical tissue samples of LUAD were collected to detect the expression of ALOX15 and its relationship with the differentiation degree and stage of lung cancer. Finally, the relationship between the expression of ALOX15 and the proliferation and differentiation of LUAD cell lines (NCI-H1944, A549, PC9) with different degrees of differentiation and the construction of ALOX15 overexpression stable lines was detected. Results ALOX15 bioinformatics analysis showed that ALOX15 decreased significantly in the early stage of LUAD and had no correlation with the survival of lung cancer patients. ALOX15 was downregulated in LUAD with low differentiation and metastasis in LUAD. LUAD cell lines showed that the lower the degree of differentiation, the lower the expression of ALOX15, and the overexpression of ALOX15 in LUAD cells inhibited the proliferation and migration of cancer cells. Conclusion These results suggest that the expression of ALOX15 is closely related to the differentiation, proliferation, and metastasis of LUAD, and that upregulation of ALOX15 may inhibit the development of LUAD, suggesting that ALOX15 is a potential biological therapeutic target. Why was this study done? Lung cancer is one of the most frequently diagnosed cancers in the world and the leading cause of cancer-related deaths worldwide. Lung cancer is a heterogeneous disease with a wide range of clinicopathologic features. Lung cancer is roughly divided into non-small cell lung cancer (85% of all diagnoses) and small cell lung cancer (15% of all diagnoses). Adenocarcinoma is a common subtype of non-small cell lung cancer, and its recurrence rate is high, and the prognosis is poor. Therefore, the pathogenesis and characteristics of adenocarcinoma are studied and explored. What did the researchers do and find? Biological information database was used to analyze the expression level of arachidonic acid-15-lipoxygenase (ALOX15) in lung adenocarcinoma, and then the expression differences were discussed through clinical samples and cell experiments. Low ALOX15 expression was detected in lung adenocarcinoma (LAUD) patients compared with normal tissues, and ALOX15 levels influenced LUAD development. By infecting A549 with lentivirus and overexpressing ALOX15 of A549 and PC-9 with PC9, it was found that ALOX15 inhibited the proliferation of tumor cells What do these findings mean? arachidonic acid-15-lipoxygenase may be one novel potential biomarker for LUAD and a potential therapeutic target