Synergistic suppressive effects on triple-negative breast cancer by the combination of JTC-801 and sodium oxamate

Triple-negative breast cancer (TNBC) poses a significant clinical challenge due to the limited targeted therapies available at present. Cancer cells preferentially use glycolysis as their primary source of energy, characterized by increased glucose uptake and lactate production. JTC-801, a nociception/orphanin FQ opioid peptide (NOP) receptor antagonist, was reported to suppress the opioid receptor-like1 (ORL1) receptor/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/nuclear factor (NF)-κB-mediated carbonic anhydrase 9 (CA9) signaling pathway. Sodium oxamate is an inhibitor of gluconeogenesis and a glycolysis inhibitor, as a competitive lactate dehydrogenase A (LDHA) inhibitor, which also produces tumor suppression due to loss of LDHA activity. However, the roles of opioid analgesic drugs (e.g., JTC-801) and glycolysis inhibitors (e.g., sodium oxamate) in TNBC have not fully been explored. Meanwhile, concurrent treatment with JTC-801 and sodium oxamate may cause synergistic anticancer effects in a TNBC model. In the present study, the combination of JTC-801 and sodium oxamate triggered cell death in the TNBC MDA MB-231 cell line. RNA-sequencing data revealed potential genes in the crosstalk between JTC-801 and sodium oxamate including ALDOC, DDIT4, DHTKD1, EIF6, ENO1, ENO3, FOXK1, FOXK2, HIF1A, MYC, PFKM, PFKP, PPARA, etc. The combination of JTC-801 and sodium oxamate provides a novel potential therapeutic strategy for TNBC patients via downregulating cell cycle- and amino acid metabolism-related pathways such as "Cell cycle-the metaphase checkpoint", "(L)-tryptophan pathways and transport", and "Glutamic acid pathway". Collectively, the present study demonstrated that the synergistic effect of co-treatment with JTC-801 and sodium oxamate significantly suppressed tumor growth and played a crucial role in tumor development, and in turn may serve as potential synergistic drugs for TNBC.

A novel combination therapy of arginine deiminase and an arginase inhibitor targeting arginine metabolism in the tumor and immune microenvironment

Tumor progression is dependent on tumor cells and their microenvironment. It is important to identify therapies that inhibit cancer cells and activate immune cells. Arginine modulation plays a dual role in cancer therapy. Arginase inhibition induced an anti-tumor effect via T-cell activation through an increase in arginine in the tumor environment. In contrast, arginine depletion by arginine deiminase pegylated with 20,000-molecular-weight polyethylene glycol (ADI-PEG 20) induced an anti-tumor response in argininosuccinate synthase 1 (ASS1)-deficient tumor cells. ADI-PEG 20 did not cause toxicity to normal immune cells, which can recycle the ADI-degraded product citrulline back to arginine. To target tumor cells and their neighboring immune cells, we hypothesized that the combination of an arginase inhibitor (L-Norvaline) and ADI-PEG 20 may trigger a stronger anticancer response. In this study, we found that L-Norvaline inhibits tumor growth in vivo. Pathway analysis based on RNA-seq data indicated that the differentially expressed genes (DEGs) were significantly enriched in some immune-related pathways. Significantly, L-Norvaline did not inhibit tumor growth in immunodeficient mice. In addition, combination treatment with L-Norvaline and ADI-PEG 20 induced a more robust anti-tumor response against B16F10 melanoma. Furthermore, single-cell RNA-seq data demonstrated that the combination therapy increased tumor-infiltrating CD8⁺ T cells and CCR7⁺ dendritic cells. The increase in infiltrated dendritic cells may enhance the anti-tumor response of CD8⁺ cytotoxic T cells, indicating a potential mechanism for the observed anti-tumor effect of the combination treatment. In addition, populations of immunosuppressive-like immune cells, such as S100a8⁺ S100a9⁺ monocytes and Retnla⁺ Retnlg⁺ TAMs, in tumors were dramatically decreased. Importantly, mechanistic analysis indicated that the processes of the cell cycle, ribonucleoprotein complex biogenesis, and ribosome biogenesis were upregulated after combination treatment. This study implied the possibility of L-Norvaline as a modulator of the immune response in cancer and provided a new potential therapy combined with ADI-PEG 20.

Repurposing nitric oxide donating drugs in cancer therapy through immune modulation

BACKGROUND

Nitric oxide-releasing drugs are used for cardiovascular diseases; however, their effects on the tumor immune microenvironment are less clear. Therefore, this study explored the impact of nitric oxide donors on tumor progression in immune-competent mice.

METHODS

The effects of three different nitric oxide-releasing compounds (SNAP, SNP, and ISMN) on tumor growth were studied in tumor-bearing mouse models. Three mouse tumor models were used: B16F1 melanoma and LL2 lung carcinoma in C57BL/6 mice, CT26 colon cancer in BALB/c mice, and LL2 lung carcinoma in NOD/SCID mice. After nitric oxide treatment, splenic cytokines and lymphocytes were analyzed by cytokine array and flow cytometry, and tumor-infiltrating lymphocytes in the TME were analyzed using flow cytometry and single-cell RNA sequencing.

RESULTS

Low doses of three exogenous nitric oxide donors inhibited tumor growth in two immunocompetent mouse models but not in NOD/SCID immunodeficient mice. Low-dose nitric oxide donors increase the levels of splenic cytokines IFN-γ and TNF-α but decrease the levels of cytokines IL-6 and IL-10, suggesting an alteration in Th2 cells. Nitric oxide donors increased the number of CD8⁺ T cells with activation gene signatures, as indicated by single-cell RNA sequencing. Flow cytometry analysis confirmed an increase in infiltrating CD8⁺ T cells and dendritic cells. The antitumor effect of nitric oxide donors was abolished by depletion of CD8⁺ T cells, indicating the requirement for CD8⁺ T cells. Tumor inhibition correlated with a decrease in a subtype of protumor macrophages and an increase in a subset of Arg1-positive macrophages expressing antitumor gene signatures. The increase in this subset of macrophages was confirmed by flow cytometry analysis. Finally, the combination of low-dose nitric oxide donor and cisplatin induced an additive cancer therapeutic effect in two immunocompetent animal models. The enhanced therapeutic effect was accompanied by an increase in the cells expressing the gene signature of NK cell.

CONCLUSIONS

Low concentrations of exogenous nitric oxide donors inhibit tumor growth in vivo by regulating T cells and macrophages. CD8⁺ T cells are essential for antitumor effects. In addition, low-dose nitric oxide donors may be combined with chemotherapeutic drugs in cancer therapy in the future.