The role of nitric oxide synthase expressed by cytokine-induced macrophages on HIF-1 regulation in tumour cells and their response to therapy

Murine macrophages were induced to over-express iNOS by treatment with a combination of cytokines, mixed with HT1080 and HCT116 human tumour cells and the toxicity of AQ4N was determined under normoxic or hypoxic conditions. The normoxic toxicity of AQ4N towards tumour cells was not affected through co-culturing with macrophages. However, under hypoxic conditions, the induction of iNOS activity in the macrophages was associated with an increase in AQ4N metabolism and a substantial increase in tumour cell toxicity, which was dependent upon the proportion of macrophages in the culture. This study is the first demonstration of tumour associated macrophage mediated pro-drug activation to result in bystander killing of human tumour cells. The oxygenase domain of the iNOS enzyme is responsible for the production of nitric oxide (NO), a potent biological mediator, whose complex role in tumour biology is still not fully understood as it seems to have both anti- and protumour effects. We were able to use the co-culture model of NO-producing macrophages and cancer cells to demonstrate that NO is also a potent tumour radiosensitiser under hypoxic conditions with a sparing effect on well-oxygenated tumour cells, also a characteristic of normal tissues. Additionally, NO produced by the macrophages resulted in a significant induction of hypoxia inducible factor-1 (HIF-1) driven transcriptional activity in the co-cultured tumour cells under both normoxic and hypoxic conditions. We therefore, suggest the use of HIF-1 inhibitors in combination with NO-based therapies and radiation to favour tumour regression.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Evaluating the Efficiency of Hyaluronic Acid for Tumor Targeting via CD44

The development of delivery systems capable of tumor targeting represents a promising strategy to overcome issues related to nonspecific effects of conventional anticancer therapies. Currently, one of the most investigated agents for cancer targeting is hyaluronic acid (HA), since its receptor, CD44, is overexpressed in many cancers. However, most of the studies on CD44/HA interaction have been so far performed in cell-free or genetically modified systems, thus leaving some uncertainty regarding which cell-related factors influence HA binding and internalization (collectively called “uptake”) into CD44-expressing cells. To address this, the expression of CD44 (both standard and variants, designated CD44s and CD44v, respectively) was evaluated in human dermal fibroblasts (HDFs) and a large panel of cancer cell lines, including breast, prostate, head and neck, pancreatic, ovarian, colorectal, thyroid, and endometrial cancers. Results showed that CD44 isoform profiles and expression levels vary across the cancer cell lines and HDF and are not consistent within the cell origin. Using composite information of CD44 expression, HA binding, and internalization, we found that the expression of CD44v can negatively influence the uptake of HA, and, instead, when cells primarily expressed CD44s, a positive correlation was observed between expression and uptake. In other words, CD44s^high cells bound and internalized more HA compared to CD44s^low cells. Moreover, CD44s^high HDFs were less efficient in uptaking HA compared to CD44s^high cancer cells. The experiments described here are the first step toward understanding the interplay between CD44 expression, its functionality, and the underlying mechanism(s) for HA uptake. The results show that factors other than the amount of CD44 receptor can play a role in the interaction with HA, and this represents an important advance with respect to the design of HA-based carriers and the selection of tumors to treat according to their CD44 expression profile

CONJUGATES OF HYALURONIC ACID AND ANTICANCER COMPOUNDS

The present invention relates to a polymer-drug conjugate wherein the polymer is hyaluronic acid and the drug is an anticancer compound. The anticancer compound is covalently linked to the hyaluronic acid by a pH-labile boronic acid-containing linkage. These conjugates can be used for the treatment of cance

Statin-induced metabolic reprogramming in head and neck cancer: a biomarker for targeting monocarboxylate transporters

Abstract Prognosis of HPV negative head and neck squamous cell carcinoma (HNSCC) patients remains poor despite surgical and medical advances and inadequacy of predictive and prognostic biomarkers in this type of cancer highlights one of the challenges to successful therapy. Statins, widely used for the treatment of hyperlipidaemia, have been shown to possess anti-tumour effects which were partly attributed to their ability to interfere with metabolic pathways essential in the survival of cancer cells. Here, we have investigated the effect of statins on the metabolic modulation of HNSCC cancers with a vision to predict a personalised anticancer therapy. Although, treatment of tumour-bearing mice with simvastatin did not affect tumour growth, pre-treatment for 2 weeks prior to tumour injection, inhibited tumour growth resulting in strongly increased survival. This was associated with increased expression of the monocarboxylate transporter 1 (MCT1) and a significant reduction in tumour lactate content, suggesting a possible reliance of these tumours on oxidative phosphorylation for survival. Since MCT1 is responsible for the uptake of mitochondrial fuels into the cells, we reasoned that inhibiting it would be beneficial. Interestingly, combination of simvastatin with AZD3965 (MCT1 inhibitor) led to further tumour growth delay as compared to monotherapies, without signs of toxicity. In clinical biopsies, prediagnostic statin therapy was associated with a significantly higher MCT1 expression and was not of prognostic value following conventional chemo-radiotherapy. These findings provide a rationale to investigate the clinical effectiveness of MCT1 inhibition in patients with HNSCC who have been taking lipophilic statins prior to diagnosis

Radiation enhances the therapeutic effect of Banoxantrone in hypoxic tumour cells with elevated levels of nitric oxide synthase

Banoxantrone (AQ4N) is a prototype hypoxia selective cytotoxin that is activated by haem containing reductases such as inducible nitric oxide synthase (iNOS). In the present study, we evaluate whether elevated levels of iNOS in human tumour cells will improve their sensitivity to AQ4N. Further, we examine the potential of radiation to increase cellular toxicity of AQ4N under normoxic (aerobic) and hypoxic conditions. We employed an expression vector containing the cDNA for human iNOS to transfect human fibrosarcoma HT1080 tumour cells. Alternatively, parental cells were exposed to a cytokine cocktail to induce iNOS gene expression and enzymatic activity. The cells were then treated with AQ4N alone and in combination with radiation in the presence or absence of the iNOS inhibitor N-methyl-L-arginine. In parental cells, AQ4N showed little difference in toxicity under hypoxic verses normoxic conditions. Notably, cells with upregulated iNOS activity showed a significant increase in sensitivity to AQ4N, but only under conditions of reduced oxygenation. When these cells were exposed to the combination of AQ4N and radiation, there was much greater cell killing than that observed with either modality alone. In the clinical development of hypoxia selective cytotoxins it is likely they will be used in combination with radiotherapy. In the present study, we demonstrated that AQ4N can selectively kill hypoxic cells via an iNOS-dependent mechanism. This hypoxia-selective effect can be augmented by combining AQ4N with radiation without increasing cytotoxicity to well-oxygenated tissues. Collectively, these results suggest that targeting hypoxic tumours with high levels of iNOS with a combination of AQ4N and radiotherapy could be a useful clinical therapeutic strategy