Calcium-binding protein S100A9 is closely related to inflammation and tumor invasion, and is one of the specific markers of myeloid-derived suppressor cells (MDSC). In this study, a recombinant polypeptide vaccine CTB-S100A9 targeting mouse calcium-binding protein S100A9 was constructed by fusion cholera toxin B subunit (CTB) with S100A9 gene. The CTB-S100A9 fusion protein was expressed in E coli. and purified by Ni⁺ affinity chromatography. Vaccinate the purified recombinant CTB-S100A9 protein supplemented with aluminum hydroxide adjuvant can break the autoimmune tolerance and produce high titer of S100A9 antibody in mice. Moreover, the S100A9 antibody produced by CTB-S100A9 vaccination is more specific and does not cross-react with S100A8. In the mouse 4T1 breast cancer model, CTB-S100A9 vaccination not only has significant tumor prevention effects, but also has significant tumor therapeutic effects. In addition, CTB-S100A9 significantly inhibited lung metastasis in 4T1 mice breast cancer model. Further analysis by flow cytometry showed that CTB-S100A9 vaccination can significantly reduce the tumor induced Treg cells and granulocyte-derived MDSC in 4T1 mice model, and reverse the tumor immunosuppressive environment, thereby promote the anti-tumor efficacy. The animal experiments in this study were carried out under the animal care guidelines approved by the Animal Ethics Committee of the Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine. This study shows that CTB-S100A9 is a good recombinant vaccine that targets the tumor immune-suppression environment and has great potential for the future clinical application.

In recent years, the role of ketone body metabolism in tumor growth, invasion and metastasis has attracted much attention. Succinyl-CoA transferase (SCOT) is a key enzyme in the metabolism of ketone bodies. Its function is to transfer the coenzyme A group of succinyl-CoA to acetoacetate and catalyze the formation of acetoacetyl-CoA, which is the first rate-limiting step in ketone metabolism. Then acetoacetyl-CoA further breaks into two molecules of acetyl-CoA and enters the tricarboxylic acid cycle. Studies have shown that SCOT is highly expressed in a variety of tumors, and is closely related to tumor progression and prognosis of patients, which makes SCOT a potential marker for clinical diagnosis and prognosis evaluation; in addition, inhibition of SCOT activity can hinder the metabolism of ketone bodies in tumor cells, that is, reduce the production of ATP, thereby inhibiting tumor growth, proliferation, invasion and metastasis. This review aims to explore the important role of SCOT in metabolic pathways and its relationship with tumorigenesis and development, and to provide new ideas for exploring tumor metabolism and targeting molecular drugs.

Signal transducer and activator of transcription 3 (STAT3) was found in an abnormal constitutively active status in certain cancer tissues, and under these circumstances the interruption of STAT3 signaling pathway was proposed with the potential anti-cancer efficacy. In this study, our previous reported STAT3 inhibitor Bt354 can inhibit tumor growth in DU145 xenograft mice without affecting body weight. In groups treated with Bt354, the inhibition rate of tumor weight was 58.8%, 62.7% and 73.5% in 10, 20, 40 mg·kg^-1 group, respectively. Particularly, the number of Ki 67 positive cells in the tumor sections was significantly decreased in Bt354 groups. Furthermore, Bt354 inhibited the nuclear translocation of STAT3 and consequently induced cell growth inhibition, apoptosis in DU145 cells. These findings suggest that Bt354 may be a potent anticancer agent for STAT3 activated prostate cancer cells. Procedures for animal study were performed with approval of the Animal Care and Use Committee of the Chinese Academy of Medical Sciences and Peking Union Medical College.

The occurrence and development of tumors are closely related to the tumor microenvironment. Among them, tumor immune microenvironment and tumor metabolic microenvironment play important roles in tumor. Tumor immunotherapy is a way to kill tumor cells by activating the body's immune system. Tumor immuno-therapy has shown good therapeutic effects in a variety of solid tumors. In recent years, significant progress has been made in tumor immunotherapy. The Warburg effect indicates that tumor cells use aerobic glycolysis to acquire energy. In the tumor, the energy metabolism pathway is abnormal, and the tumor microenvironment can induce the reprogramming of tumor cell metabolism. Therefore, targeting tumor metabolism is also of great signifi-cance for tumor treatment. In this paper, we reviewed the research progress of drug targets related to tumor immu-nology and tumor metabolism in recent years, as well as the progress of drug development.

Immunotherapy has emerged as one of the major modalities for clinical cancer therapy, along with surgery, chemotherapy, radiotherapy and targeted therapy. However, tumor-targeted delivery of immune therapeutics is challenged by a series of barriers including non-specific release, poor tumor penetration capacity, and insufficient cellular uptake of the therapeutic regimens, which seriously restricted the efficiency and efficacy of immunotherapy. To address above challenges, nanosized drug delivery systems (NDDS) have been extensively exploited to achieve tumor-targeted delivery of immunotherapy drugs. It has been well investigated that solid tumors are of unique characteristics including acidic, hypoxic and enzymatic extracellular microenvironment. Meanwhile, the tumor cells are of acidic, reductant and reactive oxygen species intracellular microenvironment. In recent years, a large variety of tumor microenvironment-activatable NDDS have been exploited to respond specifically to the stimulus of extracellular or intracellular tumor microenvironment for enhancing the accumulation, retention and penetration in the tumor tissue. These NDDS were also employed to promote intracellular uptake and tunable drug release inside the tumor cells. In this review article, we summarized the recent progress of our laboratory using the tumor microenvironment-activatable NDDS for immune efficient therapeutics delivery, and improved cancer immunotherapy. We also briefly discussed the challenges and provided perspective of NDDS-based cancer immunotherapy.

Metabolic remodeling, a well-recognized hallmark of cancer, provides biomass and energy to support the growing demand of unrestricted growth of cancer cells. In addition to metabolic supplies, the altered cell metabolism often results in the intracellular accumulation of particular metabolites. Recently, it is increasingly revealed these metabolites may exhibit metabolism-independent roles as signaling molecules, which triggers oncogenic signaling via various mechanisms including competitive inhibition, protein post-translational modifica-tions and direct protein binding. These insights provide a new perspective of metabolic remodeling in cancer progression. This review summarized the recent advancement in the understanding of metabolites as signaling molecules independent rewriting of metabolic pathways. By summarizing these progresses, this review hopes to provide a better understanding of tumor metabolic disturbance and to contribute to the discovery of novel potential therapeutic targets.

Distinct from conventional cancer therapies focusing directly on local tumors, cancer immunotherapy aims to restore or enhance immune surveillance to fight against cancer, which bears the advantages of less side effects, lasting efficacy, substantial specificity and suitability for individualized treatment. As the most powerful antigen-presenting cell type, dendritic cells (DCs) can induce potent antigen-specific immune responses in vivo. DCs-based immunotherapy acts by loading DCs with cancer antigens in various ways to elicit specific anti-tumor immune responses. Currently, pulsing DCs with cancer antigen encoding mRNAs is an antigen loading approach under extensive study, registering encouraging results in relevant immunotherapeutic clinical trials. Thus, pulsing DCs with mRNAs is a new and highly promising modality in cancer immunotherapy.

Although numbers of naked antibodies showing clinical efficacy as single agents, their therapeutic effect is limited. Chemotherapy is very effective but with relatively large side effects, so conjugation of small chemotherapeutic drugs to antibodies is one of the important methods to enhance therapeutic potential of antibodies. Antibody-drug conjugates (ADCs) represent a promising therapeutic approach for cancer patients by combining the antigen-targeting specificity of monoclonal antibodies (mAbs) with the cytotoxic potency of chemotherapeutic drugs. These modified antibodies are expected to selectively deliver chemotherapeutic drugs to tumor cells and provide sustained clinical benefit to cancer patients, at the same time, minimizing systemic toxicity. ADCs are expected to bring together the benefits of highly potent drugs on the one hand and selective binders of specific tumor antigens on the other hand. However, designing an ADC is very complex, requiring thoughtful combination of antibody, linker, and payload drugs in the context of a target and a defined cancer indication. Although many challenges remain, recent clinical success has generated intense interest in this therapeutic class.

N6-methyladenosine (m⁶A) modification is one of the most common modifications of eukaryotic mRNA, and has become a hotspot in the field of life sciences in recent years. m⁶A modification is dynamically reversible in mammalian cells and regulated by m⁶A methyltransferase (writers), demethylase (erasers), and "reader" proteins. m⁶A can regulate various biological processes of mRNA such as RNA splicing, nuclear export, protein translation and degradation. Recent studies indicated that m⁶A is important for the initiation and development of cancer. The present review summarized biological functions of m⁶A on mRNA and discussed its roles in cell proliferation, migration, invasion, cell mentalism, and angiogenesis. Further, the m⁶A can regulate the development of various cancers including acute myelocytic leukemia (AML), breast, liver and colorectal cancer. Nowadays, the inhibitors of m⁶A related enzymes including fat-mass and obesity-associated protein and AlkB homolog 5 are being developed. We further discussed the potential values of m⁶A and its related targets on cancer therapy and treatment.

Programmed cell death protein 1 (PD-1) is an important immunosuppressive molecule, which combines with programmed cell death 1 ligand 1 (PD-L1) to initiate programmed T-cell death, leading to immune escape of tumor cells. Immune checkpoint inhibitors kill tumor cells by blocking the binding of PD-1 to PD-L1 and reactivating the patient's own immune system. With the approval of anti-PD-1 monoclonal antibodies nivolumab, pembrolizumab and anti-PD-L1 monoclonal antibody atezolizumab by FDA for the treatment of melanoma, advanced non-small cell lung cancer and other cancers, cancer treatment has ushered in a new dawn. However, only 20% of patients achieved long-term efficacy after treatment, and most patients relapsed later. Therefore, it is significant to identify effective biomarkers and develop new targets to improve the response of patients to immuno-therapy. This article reviews on the mechanism of action of anti-PD-1/PD-L1 drugs in tumors, potential biomarkers and the mechanism of acquired drug resistance, as well as combination therapy under research.