Poly(I:C) treatment influences the expression of calreticulin and profilin-1 in a human HNSCC cell line: a proteomic study

Increased expression of Profilin potentiates chemotherapeutic agent-mediated tumour regression

BACKGROUND

Targeted cancer therapy is an alternative to standard chemotherapy for a better prognosis. Although its incompetency for triple-negative breast cancer (TNBC), treatment still relies on classical chemotherapy. Increasing evidence suggest that chemotherapeutic drug-induced toxic effect could be minimised by combinatorial therapy. Profilin's familiar anti-tumorigenic activity can be utilised in combination with the drug to improve efficacy, which could be promising therapeutics to treat TNBC.

METHODS

All-trans retinoic acid (ATRA) in combination with vinblastine was tested on human MDA MB-231 cell line (MB-231) (in vitro) and MB-231 borne breast cancer in nude mice (in vivo). Effects of combination treatment on tumour growth inhibition and apoptosis were examined by tumour volume, histology and PARP cleavage. ATRA-induced transcriptional regulation of profilin had been evaluated by gel-shift and reporter gene assays. Profilin's role in ATRA-induced vinblastine efficacy was validated in profilin-stable and profilin-silenced cells.

RESULTS

ATRA binds with RAR/RXR to increase the profilin expression that potentiated cell death by chemotherapeutics. ATRA priming led to vinblastine-mediated potentiation of G2-M phase cell cycle arrest in MB-231 cells and regression of breast cancer in xenograft mice at very low concentration without any adverse effects. Moreover, increased p53 and PTEN but downregulated p65 in the tumour tissues further supported the involvement of profilin for tumour regression.

CONCLUSIONS

Vinblastine at very low concentration (20 times lesser than the recommended dose for breast cancer therapeutic) significantly regress tumour growth in ATRA-primed mice without any toxic effects suggesting potential combinatorial therapeutics for TNBC.

Inbred Substrain Differences Influence Neuroimmune Response and Drinking Behavior

BACKGROUND

The inbred mouse strain C57BL/6 is widely used in both models of addiction and immunological disease. However, there are pronounced phenotypic differences in ethanol (EtOH) consumption and innate immune response between C57BL/6 substrains. The focus of this study was to examine the effects of substrain on innate immune response and neuroimmune-induced escalation of voluntary EtOH consumption. The main goal was to identify whether substrain differences in immune response can account for differences in EtOH behavior.

METHODS

We compared acute innate immune response with a viral dsRNA mimic, polyinosinic:polycytidylic acid (poly(I:C)), in brain using qRT-PCR in both C57BL/6N and C57BL/6J mice. Next, we used a neuroimmune model of escalation using poly(I:C) to compare drinking behavior between substrains. Finally, we compared brain neuroimmune response with both EtOH and repeated poly(I:C) in both substrains as a way to account for differences in EtOH behavior.

RESULTS

We found that C57BL/6 substrains have differing immune response and drinking behaviors. C57BL/6N mice have a shorter but more robust inflammatory response to acute poly(I:C). In contrast, C57BL/6J mice have a smaller but longer-lasting acute immune response to poly(I:C). In our neuroimmune-induced escalation model, C57BL/6J mice but not C57BL/6N mice escalate EtOH intake after poly(I:C). Finally, only C57BL/6J mice show enhanced proinflammatory transcript abundance after poly(I:C) and EtOH, suggesting that longer-lasting immune responses are critical to neuroimmune drinking phenotypes.

CONCLUSIONS

Altogether, this work has elucidated additional influences that substrain has on both innate immune response and drinking phenotypes. Our observations highlight the importance of considering and reporting the source and background used for production of transgenic and knockout mice. These data provide further evidence that genetic background must be carefully considered when investigating the role of neuroimmune signaling in EtOH abuse.

Triggering TLR3 pathway promotes tumor growth and cisplatin resistance in head and neck cancer cells

Over the last decades, significant advances in targeted therapies have helped provide more effective treatment for head and neck cancer patients. However, chemo-resistance to cisplatin significantly contributes to treatment failure in the clinical management of patients. In response to chemotherapeutic agents, certain molecules inside the cell are released or secreted from damaged or dead/dying cells, named damage-associated molecular patterns (DAMPs), thereby initiating an immune response through interaction with pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs). In present study, we investigated the link between cisplatin-induced DAMPs and TLR3 signaling. We found that cisplatin could be a potential activator of TLR3 and cisplatin treatment results in activation of PRRs' signaling and down-stream associated cytokine/chemokine, IFNβ, and CCL5 in TLR3^High OC2 cells, but not in TLR3^Low FaDu cells. Furthermore, knockdown of the TLR3 gene attenuates the expression of IFNβ and CCL5 mRNA and enhances the cytotoxicity of cisplatin in TLR3^High OC2 cells. To determine whether TLR3 status affects the stress response of OC2 cells to cisplatin, we generated TLR3 knockdown OC2 cells (psi-TLR3 cells) with a psiRNA-hTLR3 plasmid containing shRNA to TLR3 and control OC2 cells (psi-NT cells) expressing non-silencing shRNA. OC2 cells were more sensitive to cisplatin treatment after TLR3 knockdown. In our animal model, OC2 psi-NT cells were more tumorigenic than were OC2 psi-TLR3 cells. Together, our in vitro and in vivo data imply TLR3 may contribute to tumor development and protect cisplatin-induced DNA damage response leading to cisplatin resistance in head and neck cancer cells.

Stimulation of the toll-like receptor 3 promotes metabolic reprogramming in head and neck carcinoma cells

In this study, a possible link between the innate immune recognition receptor TLR3 and metabolic reprogramming in Head and Neck carcinoma (HNC) cells was investigated. The effects of TLR3 stimulation/knock-down were assessed under several culture conditions in 4 HNC cell-lines by cell growth assays, targeted metabolomics, and glycolysis assays based on time-resolved analysis of proton release (Seahorse analyzer). The stimulation of TLR3 by its synthetic agonist Poly(A:U) resulted in a faster growth of HNC cells under low foetal calf serum conditions. Targeted analysis of glucose metabolism pathways demonstrated a tendency towards a shift from tricarboxylic acid cycle (Krebs cycle) to glycolysis and anabolic reactions in cells treated with Poly(A:U). Glycolysis assays confirmed that TLR3 stimulation enhanced the capacity of malignant cells to switch from oxidative phosphorylation to extra-mitochondrial glycolysis. We found evidence that HIF-1α is involved in this process: addition of the TLR3 agonist resulted in a higher cell concentration of the HIF-1α protein, even in normoxia, whereas knocking-down TLR3 resulted in a lower concentration, even in hypoxia. Finally, we assessed TLR3 expression by immunohistochemistry in a series of 7 HNSCC specimens and found that TLR3 was detected at higher levels in tumors displaying a hypoxic staining pattern. Overall, our results demonstrate that TLR3 stimulation induces the Warburg effect in HNC cells in vitro, and suggest that TLR3 may play a role in tumor adaptation to hypoxia.

Toll-like receptor 3 stimulation triggers metabolic reprogramming in pharyngeal cancer cell line through Myc, MAPK, and HIF

Toll-like receptor 3 (TLR3) has a dual role in cancer; its activation can trigger apoptosis as well as stimulate cancer cell survival, proliferation, and progression. We have shown here that TLR3 activation can induce metabolic reprogramming in a pharyngeal cancer cell line, leading to increased aerobic glycolysis, cell migration, elevated levels of reactive oxidative species (ROS), and decreased anti-oxidative response. Key proteins in these signaling pathways are heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1), pyruvate kinase M2 (PKM2), and CD44 variants, which were over-expressed after TLR3 stimulation. TLR3 activation also induced upregulation of different genes involved in cancer progression (VEGF, MMP9, uPAR) and enzymes involved in glycolytic pathway. Most of the observed effects were Myc-dependent; however, some of them were also connected with MAPK and HIF signaling pathways. Since TLR3 agonists are being investigated as potential novel cancer therapy adjuvants and apoptosis inducers, alone or in combination with other therapeutic options, data presented here suggest extreme caution before their introduction into clinical practice. The fact that TLR3 ligands [poly(I:C) and poly(A:U)] can also aid cancer survival and progression, through induction of metabolic reprogramming, emphasizes the need to investigate this particular topic. Our data suggest that the combination of TLR3 ligands with Myc or MAPK inhibitors may be a way to neutralize their undesirable effects while enhancing their anti-tumor effect. © 2016 Wiley Periodicals, Inc.

Induction of rainbow trout MH class I and accessory proteins by viral haemorrhagic septicaemia virus

Major histocompatibility (MH) class I receptors are glycoproteins which play a critical role during responses to intracellular pathogens by presenting endogenous peptides to cytotoxic T cell lymphocytes (CD8+). To date, little is known about MH class I regulation at the protein level during viral infections in fish. In this study, we characterised the MH class I pathway response to polyinosinic-polycytidylic acid (poly I:C) and upon infection with viral haemorrhagic septicemia virus (VHSV) genotype IVa using the rainbow trout monocyte/macrophage cell line RTS11. A 14-day challenge with VHSV IVa at 14°C demonstrated enhanced expression of the class I heavy chain, β2 microglobulin (β2M) and tapasin, while the expression of other accessory molecules ERp57 and calreticulin remained unchanged. However, when infection occurred at 2°C no change in expression levels of any of these molecules was observed. β2M accumulated in the media of RTS11 over time, however the β2M concentrations were 2 fold higher in cultures infected with VHSV 14 days post infection. Strikingly, when cells were maintained at 2°C the secretion of β2M was significantly reduced in both infected and non-infected cultures. These results indicate that VHSV infection alters the kinetics of β2M release as well as the expression of MH class I and suggests that cellular immunity against VHSV can be compromised at low temperatures which may increase host susceptibility to this virus during the winter.

The nuclear factor-κB pathway down-regulates expression of the NKG2D ligand H60a in vitro: implications for use of nuclear factor-κB inhibitors in cancer therapy

NKG2D ligands are cell surface proteins that activate NKG2D, a receptor used by natural killer (NK) cells to detect virus-infected and transformed cells. When tumour cells express high levels of NKG2D ligands, they are rejected by the immune system. Hence, reagents that increase NKG2D ligand expression on tumour cells can be important for tumour immunotherapy. To identify genes that regulate the NKG2D ligand H60a, we performed a microarray analysis of 3'-methylcholanthrene-induced sarcoma cell lines expressing high versus low H60a levels. A20, an inhibitor of nuclear factor-κB (NF-κB) activation, was differentially expressed in H60a-hi sarcoma cells. Correspondingly, treatment of tumour cells with inhibitors of NF-κB activation, such as sulfasalazine (slz), BAY-11-7085, or a non-phosphorylatable IκB, led to increased levels of H60a protein, whereas transduction of cells with an active form of IκB kinase-β (IKKβ) led to decreased levels of H60a. The regulation probably occurred at the transcriptional level, because NF-κB pathway inhibition led to increased H60a transcripts and promoter activity. Moreover, treatment of tumour cells with slz enhanced their killing by NK cells in vitro, suggesting that NF-κB inhibition can lead to tumour cell rejection. Indeed, when we blocked the NF-κB pathway specifically in tumour cells, there was decreased tumour growth in wild-type but not immune-deficient mice. Our results suggest that reagents that can block NF-κB activity specifically in the tumour and not the host immune cells would be efficacious for tumour therapy.