The Role of Metabolism in Tumor Immune Evasion: Novel Approaches to Improve Immunotherapy

MACC1 revisited - an in-depth review of a master of metastasis

Cancer metastasis remains the most lethal characteristic of tumors mediating the majority of cancer-related deaths. Identifying key molecules responsible for metastasis, understanding their biological functions and therapeutically targeting these molecules is therefore of tremendous value. Metastasis Associated in Colon Cancer 1 (MACC1), a gene first described in 2009, is such a key driver of metastatic processes, initiating cellular proliferation, migration, invasion, and metastasis in vitro and in vivo. Since its discovery, the value of MACC1 as a prognostic biomarker has been confirmed in over 20 cancer entities. Additionally, several therapeutic strategies targeting MACC1 and its pro-metastatic functions have been developed. In this review, we will provide a comprehensive overview on MACC1, from its clinical relevance, towards its structure and role in signaling cascades as well as molecular networks. We will highlight specific biological consequences of MACC1 expression, such as an increase in stem cell properties, its immune-modulatory effects and induced therapy resistance. Lastly, we will explore various strategies interfering with MACC1 expression and/or its functions. Conclusively, this review underlines the importance of understanding the role of individual molecules in mediating metastasis.

Immune Response and Metastasis-Links between the Metastasis Driver MACC1 and Cancer Immune Escape Strategies

Metastasis remains the most critical factor limiting patient survival and the most challenging part of cancer-targeted therapy. Identifying the causal drivers of metastasis and characterizing their properties in various key aspects of cancer biology is essential for the development of novel metastasis-targeting approaches. Metastasis-associated in colon cancer 1 (MACC1) is a prognostic and predictive biomarker that is now recognized in more than 20 cancer entities. Although MACC1 can already be linked with many hallmarks of cancer, one key process-the facilitation of immune evasion-remains poorly understood. In this review, we explore the direct and indirect links between MACC1 and the mechanisms of immune escape. Therein, we highlight the signaling pathways and secreted factors influenced by MACC1 as well as their effects on the infiltration and anti-tumor function of immune cells.

Targeting MYC at the intersection between cancer metabolism and oncoimmunology

MYC activation is a known hallmark of cancer as it governs the gene targets involved in various facets of cancer progression. Of interest, MYC governs oncometabolism through the interactions with its partners and cofactors, as well as cancer immunity via its gene targets. Recent investigations have taken interest in characterizing these interactions through multi-Omic approaches, to better understand the vastness of the MYC network. Of the several gene targets of MYC involved in either oncometabolism or oncoimmunology, few of them overlap in function. Prominent interactions have been observed with MYC and HIF-1α, in promoting glucose and glutamine metabolism and activation of antigen presentation on regulatory T cells, and its subsequent metabolic reprogramming. This review explores existing knowledge of the role of MYC in oncometabolism and oncoimmunology. It also unravels how MYC governs transcription and influences cellular metabolism to facilitate the induction of pro- or anti-tumoral immunity. Moreover, considering the significant roles MYC holds in cancer development, the present study discusses effective direct or indirect therapeutic strategies to combat MYC-driven cancer progression.

Can a Low-Phosphate Diet for Chronic Kidney Disease Treat Cancer? An Interdisciplinary Literature Review

Background: Cancer therapeutics have a low success rate in clinical trials. An interdisciplinary approach is needed to translate basic, clinical, and remote fields of research knowledge into novel cancer treatments. Recent research has identified high dietary phosphate intake as a risk factor associated with cancer incidence. A model of tumor dynamics predicted that reducing phosphate levels sequestered in the tumor microenvironment could substantially reduce tumor size. Coincidently, a low-phosphate diet is already in use to help patients with chronic kidney disease manage high serum phosphate levels. Methods: A grounded-theory literature-review method was used to synthesize interdisciplinary findings from the basic and clinical sciences, including oncology, nephrology, nutritional epidemiology, and dietetic research on cancer. Results: Findings of tumor remission associated with fasting and a ketogenic diet, which lower intake of dietary phosphate, support the hypothesis that a low-phosphate diet will reduce levels of phosphate sequestered in the tumor microenvironment and reduce tumor size. Additionally, long-term effects of a low-phosphate diet may reverse dysregulated phosphate metabolism associated with tumorigenesis and prevent cancer recurrence. Conclusions: Evidence in this article provides the rationale to test a low-phosphate diet as a dietary intervention to reduce tumor size and lower risk of cancer recurrence.

E2F3 renders an immunosuppressive tumor microenvironment in nasopharyngeal carcinoma: Involvements of the transcription activation of PRC1 and BIRC5

BACKGROUND

E2F transcription factors are well-recognized oncogenic molecules, and their correlation with immune cell infiltration has recently been reported. This work studies the impacts and mechanism of E2F transcription factor 3 (E2F3) in the growth and tumor microenvironment (TME) of nasopharyngeal carcinoma (NPC).

METHODS

Aberrantly expressed transcription factors in NPC were screened by abundant bioinformatics analyses. Gene expression in NPC cells was analyzed by reverse transcription-quantitative polymerase chain reaction and Western blot analyses. Malignant behaviors of NPC cells were analyzed by cell counting kit-8, 5-ethynyl-2'-deoxyuridine labeling, Transwell assays, and xenograft tumor models. TPA-induced THP-1 cells (macrophages) were cultured in the conditioned medium of NPC cells to mimic tumor-associated macrophages (TAMs) in vivo, and these TAMs were cocultured with CD8+ T cells. Regulation of E2F3 on protein regulator of cytokinesis 1 (PRC1) and baculoviral IAP repeat containing 5 (BIRC5) was validated by chromatin immunoprecipitation and luciferase reporter assays.

RESULTS

E2F3 was highly expressed in NPC cells, and its knockdown suppressed malignant behavior and tumorigenic ability of the cells. The E2F3 knockdown condition downregulated M2 cytokines CD163 and interleukin-10 in TAMs, which further enhanced proliferation and activation of the cocultured CD8+ T cells. E2F3 promoted transcription of PRC1 and BRIC5. Furthermore, PRC1 or BRIC5 upregulation in NPC cells restored the malignant properties of NPC cells, reprogrammed the TAMs to M2 phenotype, and suppressed the CD8+ T cell proliferation and activation.

CONCLUSION

This work suggests that E2F3 renders an immunosuppressive TME in NPC by activating PRC1 and BIRC5. Suppression of any member involved might favor tumor elimination.

Cancer Metabolism and Resistance to Cell Death: Novel Therapeutic Perspectives

Deregulation of metabolism and resistance to cell death are two hallmarks of cancer [...]

iPSCs in NK Cell Manufacturing and NKEV Development

Natural killer (NK) cell immunotherapies for cancer can complement existing T cell therapies while benefiting from advancements already made in the immunotherapy field. For NK cell manufacturing, induced pluripotent stem cells (iPSCs) offer advantages including eliminating donor variation and providing an ideal platform for genome engineering. At the same time, extracellular vesicles (EVs) have become a major research interest, and purified NK cell extracellular vesicles (NKEVs) have been shown to reproduce the key functions of their parent NK cells. NKEVs have the potential to be developed into a standalone therapeutic with reduced complexity and immunogenicity compared to cell therapies. This review explores the role iPSC technology can play in both NK cell manufacturing and NKEV development.

Impact of Diets on Response to Immune Checkpoint Inhibitors (ICIs) Therapy against Tumors

Immunotherapy has revolutionized the established therapeutics against tumors. As the major immunotherapy approach, immune checkpoint inhibitors (ICIs) achieved remarkable success in the treatment of malignancies. However, the clinical gains are far from universal and durable, because of the primary and secondary resistance of tumors to the therapy, or side effects induced by ICIs. There is an urgent need to find safe combinatorial strategies that enhance the response of ICIs for tumor treatment. Diets have an excellent safety profile and have been shown to play pleiotropic roles in tumor prevention, growth, invasion, and metastasis. Accumulating evidence suggests that dietary regimens bolster not only the tolerability but also the efficacy of tumor immunotherapy. In this review, we discussed the mechanisms by which tumor cells evade immune surveillance, focusing on describing the intrinsic and extrinsic mechanisms of resistance to ICIs. We also summarized the impacts of different diets and/or nutrients on the response to ICIs therapy. Combinatory treatments of ICIs therapy with optimized diet regimens own great potential to enhance the efficacy and durable response of ICIs against tumors, which should be routinely considered in clinical settings.