Quantitative Proteome Responses to Oncolytic Reovirus in GM-CSF- and M-CSF-Differentiated Bone Marrow-Derived Cells.

The efficacy of oncolytic viruses (OVs), such as reovirus, is dictated by host immune responses, including those mediated by the pro- versus anti-inflammatory macrophages. As such, a detailed understanding of the interaction between reovirus and different macrophage types is critical for therapeutic efficacy. To explore reovirus-macrophage interactions, we performed tandem mass tag (TMT)-based quantitative temporal proteomics on mouse bone marrow-derived macrophages (BMMs) generated with two cytokines, macrophage colony stimulating factor (M-CSF) and granulocytic-macrophage colony stimulating factor (GM-CSF), representing anti- and proinflammatory macrophages, respectively. We quantified 6863 proteins across five time points in duplicate, comparing M-CSF (M-BMM) and GM-CSF (GM-BMM) in response to OV. We find that GM-BMMs have lower expression of key intrinsic proteins that facilitate an antiviral immune response, express higher levels of reovirus receptor protein JAM-A, and are more susceptible to oncolytic reovirus infection compared to M-BMMs. Interestingly, although M-BMMs are less susceptible to reovirus infection and subsequent cell death, they initiate an antireovirus adaptive T cell immune response comparable to that of GM-BMMs. Taken together, these data describe distinct proteome differences between these two macrophage populations in terms of their ability to mount antiviral immune responses.

The Role of Mitochondrial Calcium Signaling in the Pathophysiology of Cancer Cells.

The pioneering work of Richard Altman on the presence of mitochondria in cells set in motion a field of research dedicated to uncovering the secrets of the mitochondria. Despite limitations in studying the structure and function of the mitochondria, advances in our understanding of this organelle prompted the development of potential treatments for various diseases, from neurodegenerative conditions to muscular dystrophy and cancer. As the powerhouses of the cell, the mitochondria represent the essence of cellular life and as such, a selective advantage for cancer cells. Much of the function of the mitochondria relies on Ca2+ homeostasis and the presence of effective Ca2+ signaling to maintain the balance between mitochondrial function and dysfunction and subsequently, cell survival. Ca2+ regulates the mitochondrial respiration rate which in turn increases ATP synthesis, but too much Ca2+ can also trigger the mitochondrial apoptosis pathway; however, cancer cells have evolved mechanisms to modulate mitochondrial Ca2+ influx and efflux in order to sustain their metabolic demand and ensure their survival. Therefore, targeting the mitochondrial Ca2+ signaling involved in the bioenergetic and apoptotic pathways could serve as potential approaches to treat cancer patients. This chapter will review the role of Ca2+ signaling in mediating the function of the mitochondria and its involvement in health and disease with special focus on the pathophysiology of cancer.

TRP channels in gastric cancer: New hopes and clinical perspectives.

Gastric cancer is a multifactorial disease associated with a combination of and environmental factors. Each year, one million new gastric cancer cases are diagnosed worldwide and two-thirds end up losing the battle with this devastating disease. Currently, surgery represents the only effective treatment option for patients with early stage tumors. However, the asymptomatic phenotype of this disease during the early stages poses as a significant limiting factor to diagnosis and often renders treatments ineffective. To address these issues, scientists are focusing on personalized medicine and discovering new ways to treat cancer patients. Emerging therapeutic options include the transient receptor potential (TRP) channels. Since their discovery, TRP channels have been shown to contribute significantly to the pathophysiology of various cancers, including gastric cancer. This review will summarize the current knowledge about gastric cancer and provide a synopsis of recent advancements on the role and involvement of TRP channels in gastric cancer as well as a discussion of the benefits of targeting TPR channel in the clinical management of gastric cancer.

TRPM2 ion channel promotes gastric cancer migration, invasion and tumor growth through the AKT signaling pathway.

Transient Receptor Potential Melastatin-2 (TRPM2) ion channel is emerging as a great therapeutic target in many types of cancer, including gastric cancer - a major health threat of cancer related-death worldwide. Our previous study demonstrated the critical role of TRPM2 in gastric cancer cells bioenergetics and survival; however, its role in gastric cancer metastasis, the major cause of patient death, remains unknown. Here, using molecular and functional assays, we demonstrate that TRPM2 downregulation significantly inhibits the migration and invasion abilities of gastric cancer cells, with a significant reversion in the expression level of metastatic markers. These effects were concomitant with decreased Akt and increased PTEN activities. Finally, TRPM2 silencing resulted in deregulation of metastatic markers and abolished the tumor growth ability of AGS gastric cancer cells in NOD/SCID mice. Taken together, our results provide compelling evidence on the important function of TRPM2 in the modulation of gastric cancer cell invasion likely through controlling the PTEN/Akt pathway.

The hidden potential of lysosomal ion channels: A new era of oncogenes.

Lysosomes serve as the control centre for cellular clearance. These membrane-bound organelles receive biomolecules destined for degradation from intracellular and extracellular pathways; thus, facilitating the production of energy and shaping the fate of the cell. At the base of their functionality are the lysosomal ion channels which mediate the function of the lysosome through the modulation of ion influx and efflux. Ion channels form pores in the membrane of lysosomes and allow the passage of ions, a seemingly simple task which harbours the potential of overthrowing the cell's stability. Considered the master regulators of ion homeostasis, these integral membrane proteins enable the proper operation of the lysosome. Defects in the structure or function of these ion channels lead to the development of lysosomal storage diseases, neurodegenerative diseases and cancer. Although more than 50 years have passed since their discovery, lysosomes are not yet fully understood, with their ion channels being even less well characterized. However, significant improvements have been made in the development of drugs targeted against these ion channels as a means of combating diseases. In this review, we will examine how Ca2+, K+, Na+ and Cl- ion channels affect the function of the lysosome, their involvement in hereditary and spontaneous diseases, and current ion channel-based therapies.

TRPM2 channel-mediated regulation of autophagy maintains mitochondrial function and promotes gastric cancer cell survival via the JNK-signaling pathway.

A lack of effective treatment is one of the main factors contributing to gastric cancer-related death. Discovering effective targets and understanding their underlying anti-cancer mechanism are key to achieving the best response to treatment and to limiting side effects. Although recent studies have shown that the cation channel transient receptor potential melastatin-2 (TRPM2) is crucial for cancer cell survival, the exact mechanism remains unclear, limiting its therapeutic potential. Here, using molecular and functional assays, we investigated the role of TRPM2 in survival of gastric cancer cells. Our results indicated that TRPM2 knockdown in AGS and MKN-45 cells decreases cell proliferation and enhances apoptosis. We also observed that the TRPM2 knockdown impairs mitochondrial metabolism, indicated by a decrease in basal and maximal mitochondrial oxygen consumption rates and ATP production. These mitochondrial defects coincided with a decrease in autophagy and mitophagy, indicated by reduced levels of autophagy- and mitophagy-associated proteins (i.e. ATGs, LC3A/B II, and BNIP3). Moreover, we found that TRPM2 modulates autophagy through a c-Jun N-terminal kinase (JNK)-dependent and mechanistic target of rapamycin-independent pathway. We conclude that in the absence of TRPM2, down-regulation of the JNK-signaling pathway impairs autophagy, ultimately causing the accumulation of damaged mitochondria and death of gastric cancer cells. Of note, by inhibiting cell proliferation and promoting apoptosis, the TRPM2 down-regulation enhanced the efficacy of paclitaxel and doxorubicin in gastric cancer cells. Collectively, we provide compelling evidence that TRPM2 inhibition may benefit therapeutic approaches for managing gastric cancer.

Dendritic Cells in Oncolytic Virus-Based Anti-Cancer Therapy.

Dendritic cells (DCs) are specialized antigen-presenting cells that have a notable role in the initiation and regulation of innate and adaptive immune responses. In the context of cancer, appropriately activated DCs can induce anti-tumor immunity by activating innate immune cells and tumor-specific lymphocytes that target cancer cells. However, the tumor microenvironment (TME) imposes different mechanisms that facilitate the impairment of DC functions, such as inefficient antigen presentation or polarization into immunosuppressive DCs. These tumor-associated DCs thus fail to initiate tumor-specific immunity, and indirectly support tumor progression. Hence, there is increasing interest in identifying interventions that can overturn DC impairment within the TME. Many reports thus far have studied oncolytic viruses (OVs), viruses that preferentially target and kill cancer cells, for their capacity to enhance DC-mediated anti-tumor effects. Herein, we describe the general characteristics of DCs, focusing on their role in innate and adaptive immunity in the context of the TME. We also examine how DC-OV interaction affects DC recruitment, OV delivery, and anti-tumor immunity activation. Understanding these roles of DCs in the TME and OV infection is critical in devising strategies to further harness the anti-tumor effects of both DCs and OVs, ultimately enhancing the efficacy of OV-based oncotherapy.

Newly recruited CD11b+, GR-1+, Ly6C(high) myeloid cells augment tumor-associated immunosuppression immediately following the therapeutic administration of oncolytic reovirus.

Tumor-associated immunosuppression aids cancer cells to escape immune-mediated attack and subsequent elimination. Recently, however, many oncolytic viruses, including reovirus, have been reported to overturn such immunosuppression and promote the development of a clinically desired antitumor immunity, which is known to promote favorable patient outcomes. Contrary to this existing paradigm, in this article we demonstrate that reovirus augments tumor-associated immunosuppression immediately following its therapeutic administration. Our data show that reovirus induces preferential differentiation of highly suppressive CD11b(+), Gr-1(+), Ly6C(high) myeloid cells from bone marrow hematopoietic progenitor cells. Furthermore, reovirus administration in tumor-bearing hosts drives time-dependent recruitment of CD11b(+), Gr-1(+), Ly6C(high) myeloid cells in the tumor milieu, which is further supported by virus-induced increased expression of numerous immune factors involved in myeloid-derived suppressor cell survival and trafficking. Most importantly, CD11b(+), Gr-1(+), Ly6C(high) myeloid cells specifically potentiate the suppression of T cell proliferation and are associated with the absence of IFN-γ response in the tumor microenvironment early during oncotherapy. Considering that the qualitative traits of a specific antitumor immunity are largely dictated by the immunological events that precede its development, our findings are of critical importance and must be considered while devising complementary interventions aimed at promoting the optimum efficacy of oncolytic virus-based anticancer immunotherapies.