Interplay between microbial-derived GABA and host GABA receptor signaling collectively influence the tumorigenic function of GABA in colon cancer.

Although classically recognized as a neurotransmitter, gamma aminobutyric acid (GABA) has also been identified in colonic tumors. Moreover, the gut microbiome represents another potential source of GABA. Both GABAA and GABAB receptors have been implicated in contributing to the effects of GABA in colorectal cancer, with both pro- and anti-tumorigenic functions identified. However, their subunit composition is often overlooked. Studies to date have not addressed whether the GABA-producing potential of the microbiome changes over the course of colon tumor development or whether receptor subunit expression patterns are altered in colon cancer. Therefore, we investigated the clusters of orthologous group frequencies of glutamate decarboxylase (GAD) in feces from two murine models of colon cancer and found that the frequency of microbial GAD was significantly decreased early in the tumorigenic process. We also determined that microbial-derived GABA inhibited proliferation of colon cancer cells in vitro and that this effect of GABA on SW480 cells involved both GABAA and GABAB receptors. GABA also inhibited prostaglandin E2 (PGE2)-induced proliferation and interleukin-6 (IL-6) expression in these cells. Gene expression correlations were assessed using the "Cancer Exploration" suite of the TIMER2.0 web tool and identified that GABA receptor subunits were differentially expressed in human colon cancer. Moreover, GABAA receptor subunits were predominantly positively associated with PGE2 synthase, cyclooxygenase-2 and IL-6. Collectively, these data demonstrate decreased potential of the microbiome to produce GABA during tumorigenesis, a novel anti-tumorigenic pathway for GABA, and that GABA receptor subunit expression adds a further layer of complexity to GABAergic signaling in colon cancer.

Second-line treatment of advanced hepatocellular carcinoma: Time for more individualized treatment options?

Hepatocellular carcinoma (HCC) is the most frequently diagnosed primary tumor of the liver and is usually detected as advanced disease. It is an aggressive disease that often progresses rapidly when it fails to respond to treatment. As such, patients have limited opportunities to try different subsequent-line treatment regimens. In the last 5 years, the number of agents and/or regimens available for the treatment of advanced HCC has significantly increased, which has made treatment choices for this patient population increasingly complex. In the second-line setting, several phase III trials of regorafenib (RESORCE), ramucirumab (REACH/REACH-2), and cabozantinib (CELESTIAL) have demonstrated clinically meaningful survival benefits in patients with the disease. However, the median overall survival of patients with advanced HCC remains unchanged at approximately 12 mo from the start of systemic second-line therapy, with a limited duration of response. Evidence from the REACH/REACH-2 trials demonstrated for the first time that baseline alpha-fetoprotein (AFP) levels can be used as an identification factor to select those who are likely to benefit the most from ramucirumab treatment. Ramucirumab is both well tolerated and efficacious and has a clinically acceptable safety profile. Therefore, it should be considered an option for patients with AFP levels ≥ 400 ng/mL.

Electrochemotherapy Causes Caspase-Independent Necrotic-Like Death in Pancreatic Cancer Cells.

Pancreatic cancer represents a major challenge in oncology. Poor permeability of the pancreas and resistance to currently available therapies are impediments to improved patient survival. By transiently increasing cell membrane porosity and increasing drug uptake, Electrochemotherapy (ECT) has the potential to overcome these issues. In this study, we have evaluated the response of human and murine pancreatic cancer cells, in vitro, to electroporation in combination with Bleomycin, Cisplatin, or Oxaliplatin (ECT). The cytotoxic actions of all three drugs are potentiated when combined with electroporation in these cells. The biochemical and morphological changes post ECT are associated with immunogenic cell death that occurs with necroptosis rather than apoptosis. Moreover, ECT-induced cell death is rescued by Nec-1 suggesting that necroptosis may play a role in cell death mediated by cancer therapies.

Engagement of Fas differentially regulates the production of LPS-induced proinflammatory cytokines and type I interferons.

Fas (CD95) signalling is best known for its role in apoptosis, however, recent reports have shown it to be involved in other cellular responses as well, including inflammation. Fas and its adaptor protein FADD are known to negatively regulate LPS-induced proinflammatory responses, but their role in LPS-induced type I interferon production is unknown. Here, we demonstrate that Fas engagement on macrophages, using an agonistic Fas antibody CH11, augments LPS-induced NF-κB responses, causing increased production of TNFα, IL-8, IL-6 and IL-12. Conversely, costimulation with both LPS and CH11 causes a significant reduction in the level of interferon-beta (IFNß) production. This differential effect involves the Fas adaptor FADD because while LPS-induced IL-6 production increased in FADD-/- murine embryonic fibroblasts, LPS-induced IFNß production was significantly reduced in these cells. Overexpression of a dominant negative form of FADD (FADD-DD) inhibits LPS-induced IFNß luciferase but not LPS-induced NF-κB luciferase. In contrast, overexpression of full-length FADD inhibited LPS-induced NF-κB luciferase activation but was seen to augment LPS-induced IFNß luciferase. Moreover, FADD-DD inhibits TRIF-, TRAM-, IKKε-, TBK-1- and TRAF3-induced IFNß luciferase production, with coimmunoprecipitation experiments demonstrating an interaction between FADD and TRIF. These data identify FADD as a novel component of the noncanonical Toll-like receptor 4/IFNß signalling pathway and demonstrate that both Fas and its adaptor FADD can differentially regulate the production of LPS-induced proinflammatory cytokines and type I interferons.

Combination of electroporation delivered metabolic modulators with low-dose chemotherapy in osteosarcoma.

BACKGROUND: Osteosarcoma accounts for roughly 60% of all malignant bone tumors in children and young adults. The five-year survival rate for localized tumors after surgery and chemotherapy is approximately 70% whilst it drastically reduces to 15-30% in metastatic cases. Metabolic modulation is known to increase sensitivity of cancers to chemotherapy. A novel treatment strategy in Osteosarcoma is needed to battle this devastating malady. RESULTS: Electroporation-delivered metabolic modulators were more effective in halting the cell cycle of Osteosarcoma cells and this negatively affects their ability to recover and proliferate, as shown in colony formation assays. Electroporation-delivered metabolic modulators increase the sensitivity of Osteosarcoma cells to chemotherapy and this combination reduces their survivability. CONCLUSION: This novel treatment approach highlights the efficacy of electroporation in the delivery of metabolic modulators in Osteosarcoma cells, and increased sensitivity to chemotherapy allowing for a lower dose to be therapeutic. METHODS: Metabolic modulations of two Osteosarcoma cell lines were performed with clinically available modulators delivered using electroporation, and its combination with low-dose Cisplatin. The effects of Dicholoroacetic acid, 2-Deoxy-D-glucose and Metformin on cell cycle and recovery of Osteosarcoma cells were assessed. Their sensitivity to chemotherapy was also assessed when treated in combination with electroporation-delivered metabolic modulators.

Glycolysis inhibition as a cancer treatment and its role in an anti-tumour immune response.

Increased glycolysis is the main source of energy supply in cancer cells that use this metabolic pathway for ATP generation. Altered energy metabolism is a biochemical fingerprint of cancer cells that represents one of the "hallmarks of cancer". The immune system can prevent tumour growth by eliminating cancer cells but this editing process ultimately results in poorly immunogenic cells remaining allowing for unchallenged tumour growth. In this review we look at the glycolysis pathway as a target for cancer treatments. We also examine the interplay between the glycolysis modulation and the immune response as an anti-cancer therapy.

Engagement of Fas on Macrophages Modulates Poly I:C induced cytokine production with specific enhancement of IP-10.

Viral double-stranded RNA (dsRNA) is recognised by pathogen recognition receptors such as Toll-Like Receptor 3 (TLR3) and retinoic acid inducible gene-I (RIG-I), and results in cytokine and interferon production. Fas, a well characterised death receptor, has recently been shown to play a role in the inflammatory response. In this study we investigated the role of Fas in the anti-viral immune response. Stimulation of Fas on macrophages did not induce significant cytokine production. However, activation of Fas modified the response of macrophages to the viral dsRNA analogue poly I:C. In particular, poly I:C-induced IP-10 production was significantly enhanced. A similar augmentation of IP-10 by Fas was observed following stimulation with both poly A:U and Sendai virus. Fas activation suppressed poly I:C-induced phosphorylation of the MAP kinases p38 and JNK, while overexpression of the Fas adaptor protein, Fas-associated protein with death domain (FADD), activated AP-1 and inhibited poly I:C-induced IP-10 production. Consistent with an inhibitory role for AP-1 in IP-10 production, mutation of the AP-1 binding site on the IP-10 promoter resulted in augmented poly I:C-induced IP-10. These results demonstrate that engagement of the Fas receptor plays a role in modifying the innate immune response to viral RNA.

Intestinal expression of Fas and Fas ligand is upregulated by bacterial signaling through TLR4 and TLR5, with activation of Fas modulating intestinal TLR-mediated inflammation.

TLRs play an important role in mediating intestinal inflammation and homeostasis. Fas is best studied in terms of its function in apoptosis, but recent studies demonstrate that Fas signaling may mediate additional functions such as inflammation. The role of Fas, and the Fas ligand (FasL), in the intestine is poorly understood. The aim of this study was to evaluate potential cross-talk between TLRs and Fas/FasL system in intestinal epithelial cells (IECs). IECs were stimulated with TLR ligands, and expression of Fas and FasL was investigated. Treatment with TLR4 and TLR5 ligands, but not TLR2 and 9 ligands, increased expression of Fas and FasL in IECs in vitro. Consistent with this finding, expression of intestinal Fas and FasL was reduced in vivo in the epithelium of TLR4 knockout (KO), 5KO, and germ-free mice, but not in TLR2KO mice. Modulating Fas signaling using agonistic anti-Fas augmented TLR4- and TLR5-mediated TNF-α and IL-8 production by IECs. In addition, suppression of Fas in IECs reduced the ability of TLR4 and TLR5 ligands and the intestinal pathogens Salmonella typhimurium and Listeria monocytogenes to induce the expression of IL-8. In conclusion, this study demonstrates that extensive cross-talk in IECs occurs between the Fas and TLR signaling pathways, with the FasL/Fas system playing a role in TLR-mediated inflammatory responses in the intestine.