• BMB Reports
• /
• v.54 no.8
• /
• pp.431-436
• /
• 2021

In recent years, restoring anti-tumor immunity has garnered a growing interest in cancer treatment. As potential therapeutics, immune checkpoint inhibitors have demonstrated benefits in many clinical studies. Although various methods have been applied to suppress immune checkpoints to boost anti-tumor immunity, including the use of immune checkpoint inhibitors, there are still unmet clinical needs to improve the response rate of cancer treatment. Here, we show that acetate can suppress the expression of poliovirus receptor (PVR/CD155), a ligand for immune checkpoint, in colon cancer cells. We demonstrated that acetate treatment could enhance effector responses of CD8⁺ T cells by decreasing the expression of PVR/CD155 in cancer cells. We also found that acetate could reduce the expression of PVR/CD155 by deactivating the PI3K/AKT pathway. These results demonstrate that acetate-mediated expression of PVR/CD155 in cancer cells might potentiate the anti-tumor immunity in the microenvironment of cancer. Our findings indicate that maintaining particular acetate concentrations could be a complementary strategy in current cancer treatment.

• Biomolecules & Therapeutics
• /
• v.26 no.1
• /
• pp.4-9
• /
• 2018

Cancer metabolism as a field of research was founded almost 100 years ago by Otto Warburg, who described the propensity for cancers to convert glucose to lactate despite the presence of oxygen, which in yeast diminishes glycolytic metabolism known as the Pasteur effect. In the past 20 years, the resurgence of interest in cancer metabolism provided significant insights into processes involved in maintenance metabolism of non-proliferating cells and proliferative metabolism, which is regulated by proto-oncogenes and tumor suppressors in normal proliferating cells. In cancer cells, depending on the driving oncogenic event, metabolism is re-wired for nutrient import, redox homeostasis, protein quality control, and biosynthesis to support cell growth and division. In general, resting cells rely on oxidative metabolism, while proliferating cells rewire metabolism toward glycolysis, which favors many biosynthetic pathways for proliferation. Oncogenes such as MYC, BRAF, KRAS, and PI3K have been documented to rewire metabolism in favor of proliferation. These cell intrinsic mechanisms, however, are insufficient to drive tumorigenesis because immune surveillance continuously seeks to destroy neo-antigenic tumor cells. In this regard, evasion of cancer cells from immunity involves checkpoints that blunt cytotoxic T cells, which are also attenuated by the metabolic tumor microenvironment, which is rich in immuno-modulating metabolites such as lactate, 2-hydroxyglutarate, kynurenine, and the proton (low pH). As such, a full understanding of tumor metabolism requires an appreciation of the convergence of cancer cell intrinsic metabolism and that of the tumor microenvironment including stromal and immune cells.

• Animal cells and systems
• /
• v.16 no.3
• /
• pp.215-223
• /
• 2012

Recently it has been reported that immunization with heat-killed tumor cells (HK vaccine) induces anti-tumor immune responses in mice. To investigate how HKvaccine elicits anti-tumor specific adaptive immunity, we examined the effect of HK vaccination on innate immune cells such as dendritic cells (DCs), which are essential for the generation of adaptive immunity. Upon stimulation with HK vaccine, DCs matured to promote not only the upregulation of co-stimulatory molecules but also secretion of cytokine IL12. Furthermore, HK vaccine-treated DCs migrated more efficiently to draining lymph nodes compared with untreated ones. Taken together, HK vaccine can be useful as an adjuvant to activate DCs for anti-tumor immune responses.

• Molecules and Cells
• /
• v.46 no.3
• /
• pp.142-152
• /
• 2023

Nuclear factor erythroid 2-related factor 2 (Nrf2) mediates the cellular antioxidant response, allowing adaptation and survival under conditions of oxidative, electrophilic and inflammatory stress, and has a role in metabolism, inflammation and immunity. Activation of Nrf2 provides broad and long-lasting cytoprotection, and is often hijacked by cancer cells, allowing their survival under unfavorable conditions. Moreover, Nrf2 activation in established human tumors is associated with resistance to chemo-, radio-, and immunotherapies. In addition to cancer cells, Nrf2 activation can also occur in tumor-associated macrophages (TAMs) and facilitate an anti-inflammatory, immunosuppressive tumor immune microenvironment (TIME). Several cancer cell-derived metabolites, such as itaconate, L-kynurenine, lactic acid and hyaluronic acid, play an important role in modulating the TIME and tumor-TAMs crosstalk, and have been shown to activate Nrf2. The effects of Nrf2 in TIME are context-depended, and involve multiple mechanisms, including suppression of proinflammatory cytokines, increased expression of programmed cell death ligand 1 (PD-L1), macrophage colony-stimulating factor (M-CSF) and kynureninase, accelerated catabolism of cytotoxic labile heme, and facilitating the metabolic adaptation of TAMs. This understanding presents both challenges and opportunities for strategic targeting of Nrf2 in cancer.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.310.2-310.2
• /
• 2002

Macrophage activated by LPS/IFN-${\gamma}$ playa important role in imflammation. innate immunity and tumor immunity. The recent report has indicated that LPS treated bone marrow macrophages were induced apoptosis. but IFN-${\gamma}$ protects from apoptosis induced by several stimuli in complete medium condition (Jordi et al.. Immunity. Vo1.11. 103-113. 1999). (omitted)

• Korean Journal of Clinical Laboratory Science
• /
• v.54 no.1
• /
• pp.38-48
• /
• 2022

Carcinoembryonic antigen (CEA) is an oncofetal antigen primarily detected in the peripheral blood of cancer patients, particularly in those with colorectal cancer. CEA is considered a valuable target for antigen-specific immunotherapy. In this study, we induced the anti-tumor immunity for CEA through the administration of a dendritic cell (DC) vaccine. However, there was a limitation in inducing tumor regression in the DC vaccinated mice. To enhance the efficacy of anti-tumor immunity in MC38/CEA2 tumor-bearing mice, we evaluated the effects of DC vaccine in combination with cyclophosphamide (CYP). Administration of CYP 100 mg/kg in mice resulted in significant inhibition of tumor growth in the 2-day tumor model, whereas a lower inhibition of tumor growth was seen in the 10-day tumor model. Therefore, the 10-day tumor model was selected for testing chemo-immunotherapy. The combined CYP and DC vaccine not only increased tumor antigen-specific immune responses but also induced synergistic anti-tumor immunity. Furthermore, the adverse effects of CYP such as weight loss and immunosuppression by regulatory T cells and myeloid-derived suppressor cells showed a significant reduction in the combined chemo-immunotherapy treatment compared with CYP alone. Our data suggest that chemoimmunotherapy with the DC vaccine may offer a new therapeutic strategy to induce a potent anti-tumor effect and reduce the adverse effects of chemotherapy.

• Archives of Pharmacal Research
• /
• v.9 no.3
• /
• pp.183-187
• /
• 1986

Some of organophosphate pesticides which are the most heavily used in Korea, were examined for their effects on the murine immune system. Immunotoxicological assay parameters adaopted in this study were Arthus reaction for humoral immunity, delayed type hypersensitivity reaction for cell mediate immunity, carbon clearance for macrophage function and susceptiility to tumor challenge. Subchronic exposure of rodents to the pesticides resulted in the marked suppression of immune functions and enhancement of susceptibility to tumor challenge. Among the pesticides tested (fenitrothion, fenthion, diazinon and EPN), fenitrothion was the most suppressive in Arthus and delayed type hypersensitivity reaction.

• The Microorganisms and Industry
• /
• v.20 no.3
• /
• pp.14-21
• /
• 1994

Low molecular weight molecules and high molecular weight substances were found to have anti-tumor and immuno-modulating activity. Previously polysaccharides have been received much attention because of adhesives, food additives or animal foods (Whistler et al., 1976). In effort of developing new anti-tumor substances with low toxicity, numerous polysaccharides from yeast, algae, bacteria, higher plants and especially fungi have been investigated for anti-tumor and immuno-modulating activities. Thus the high molecular weight molecule was reported to have anti-tumor activity through host mediated immunity. In this brief article, attention will be paid to polysaccharides which is especially fungal origin.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.12
• /
• pp.1919-1927
• /
• 2006

Tumor cells genetically engineered to secrete cytokines are effective in tumor therapy, but various unexpected side effects are observed, which may result from the bulk activation of various bystander cells. In this study, we tested tumor vaccines expressing various membrane-bound forms of IL-2 (mbIL-2) on MethA fibrosarcoma cells to focus antitumor immune responses to CTL. Chimeric forms of IL-2 with whole CD4, deletion forms of CD4, and TNF were expressed on the tumor cell surface, respectively. Tumor clones expressing mbIL-2 or secretory form of IL-2 were able to support the cell growth of CTLL-2, an IL-2-dependent T cell line, and the proliferation of spleen cells from 2C TCR transgenic mice that are responsive to the $p2Ca/L^d$ MHC class I complex. Expression of mbIL-2 on tumor cells reduced the tumorigenicity of tumor cells, and the mice that once rejected the live IL-2/TNF tumor clone acquired systemic immunity against wild-type MethA cells. The IL-2/TNF clone was inferior to other clones in tumor formation, and superior in the stimulation of the CD8+ T cell population in vitro. These results suggest that the IL-2/TNF clone is the best tumor vaccine, and may stimulate CD8+ T cells by direct priming. Expression of IL-2/TNF on tumor cells may serve as an effective gene therapy method to ameliorate the side effects encountered in the recombinant cytokine therapy and the conventional cytokine gene therapy using the secretory form of IL-2.

• Journal of Life Science
• /
• v.16 no.6
• /
• pp.904-910
• /
• 2006

Dendritic cells (DCs) are the only antigen presenting cells (APCs) capable of initiating immune responses, which is crucial for priming the specific cytotoxic T lymphocyte (CTL) response and tumor immunity. Upon activation by DCs, CD4+ helper T cells can cross-prime CD8+ CTLs via IL-12. However, recently activated DCs were described to prime in vitro strong T helper cell type 1 $(Th_1)$ responses, whereas at later time points, they preferentially prime $Th_2$ cells. Therfore, we examined in this study the optimum kinetic state of DCs activation impacted on in vivo priming of tumor-specific CTLs by using ovalbumin (OVA) tumor antigen model. Bone-marrow-derived DCs showed an appropriate expression of surface MHC and costimulatory molecules after 6 or 7-day differentiation. The 6-day differentiated DCs pulsed with OVA antigen for 8 h (8-h DC) and followed by restimulation with LPS for 24 h maintained high interleukin (IL)-12 production potential, accompanying the decreased level in their secretion by delayed re-exposure time to LPS. Furthermore, immunization with 8-h DC induced higher intracellular $interferon(IFN)-{\gamma}+/CD8+T$ cells and elicited more powerful cytotoxicity of splenocytes to EG7 cells, a clone of EL4 cells transfected with an OVA cDNA, than immunization with 24-h DC. In the animal study for the evaluation of therapeutic or protective antitumor immunity, immunization with 8-h DC induced an effective antitumor immunity against tumor of EG7 cells and completely protected mice from tumor formation and prolonged survival, respectively. The most commonly used and clinically applied DC-based vaccine is based on in vitro antigen loading for 24 h. However, our data indicated that antigen stimulation over 8 h decreased antitumor immunity with functional exhaustion of DCs, and that the 8-h DC would be an optimum activation state impacted on in vivo priming of tumor-specific CTLs and subsequently lead to induction of strong antitumor immunity.