Toby Mellows

Tumour-infiltrating lymphocytes predict for outcome in HPV-positive oropharyngeal cancer

Background:Human papillomavirus (HPV)-positive oropharyngeal cancer (OPSCC) is associated with improved survival compared with HPV-negative disease. However, a minority of HPV-positive patients have poor prognosis. Currently, there is no generally accepted strategy for identifying these patients.Methods:We retrospectively analysed 270 consecutively treated OPSCC patients from three centres for effects of clinical, pathological, immunological, and molecular features on disease mortality. We used Cox regression to examine associations between factors and OPSCC death, and developed a prognostic model for 3-year mortality using logistic regression analysis.Results:Patients with HPV-positive tumours showed improved survival (hazard ratio (HR), 0.33 (0.21–0.53)). High levels of tumour-infiltrating lymphocytes (TILs) stratified HPV-positive patients into high-risk and low-risk groups (3-year survival; HPV-positive/TILhigh=96%, HPV-positive/TILlow=59%). Survival of HPV-positive/TILlow patients did not differ from HPV-negative patients (HR, 1.01; P=0.98). We developed a prognostic model for HPV-positive tumours using a ‘training’ cohort from one centre; the combination of TIL levels, heavy smoking, and T-stage were significant (AUROC=0·87). This model was validated on patients from the other centres (detection rate 67%; false-positive rate 5.6%; AUROC=0·82).Interpretation:Our data suggest that an immune response, reflected by TIL levels in the primary tumour, has an important role in the improved survival seen in most HPV-positive patients, and is relevant for the clinical evaluation of HPV-positive OPSCC.

A subset of myofibroblastic cancer-associated fibroblasts regulate collagen fiber elongation, which is prognostic in multiple cancers

Collagen structure has been shown to influence tumor cell invasion, metastasis and clinical outcome in breast cancer. However, it remains unclear how it affects other solid cancers. Here we utilized multi-photon laser scanning microscopy and Second Harmonic Generation to identify alterations to collagen fiber structure within the tumor stroma of head & neck, esophageal and colorectal cancers. Image segmentation algorithms were then applied to quantitatively characterize these morphological changes, showing that elongated collagen fibers significantly correlated with poor clinical outcome (Log Rank p < 0.05). We used TGF-β treatment to model fibroblast conversion to smooth muscle actin SMA-positive cancer associated fibroblasts (CAFs) and found that these cells induce the formation of elongated collagen fibers in vivo. However, proteomic/transcriptomic analysis of SMA-positive CAFs cultured ex-vivo showed significant heterogeneity in the expression of genes with collagen fibril organizing gene ontology. Notably, stratifying patients according to stromal SMA-positivity and collagen fiber elongation was found to provide a highly significant correlation with poor survival in all 3 cancer types (Log Rank p ≤ 0.003). In summary, we show that increased collagen fiber length correlates with poor patient survival in multiple tumor types and that only a sub-set of SMA-positive CAFs can mediate the formation of this collagen structure.

Staging and treatment of oropharyngeal cancer in the human papillomavirus era

Oropharyngeal squamous cell carcinoma (SCC) is staged using the TNM system. Human papillomavirus (HPV)‐positive tumors have improved prognosis, despite presenting at advanced stage. Optimal treatment and stratification of HPV‐positive patients are not clearly defined.

Staging and treatment of oropharyngeal cancer in the HPV ERA

Oropharyngeal squamous cell carcinoma (SCC) is staged using the TNM system. Human papillomavirus (HPV)‐positive tumors have improved prognosis, despite presenting at advanced stage. Optimal treatment and stratification of HPV‐positive patients are not clearly defined.

Induction of fibroblast senescence generates a non-fibrogenic myofibroblast phenotype that differentially impacts on cancer prognosis

Cancer-associated fibroblasts (CAF) remain a poorly characterized, heterogeneous cell population. Here we characterized two previously described tumor-promoting CAF sub-types, smooth muscle actin (SMA)-positive myofibroblasts and senescent fibroblasts, identifying a novel link between the two. Analysis of CAF cultured ex vivo, showed that senescent CAF are predominantly SMA-positive; this was confirmed by immunochemistry in head & neck (HNSCC) and esophageal (EAC) cancers. In vitro, we found that fibroblasts induced to senesce develop molecular, ultrastructural and contractile features typical of myofibroblasts and this is dependent on canonical TGF-β signaling. Similar to TGF-β1-generated myofibroblasts, these cells secrete soluble factors that promote tumor cell motility. However, RNA-sequencing revealed significant transcriptomic differences between the two SMA-positive CAF groups, particularly in genes associated with extracellular matrix (ECM) deposition and organization, which differentially promote tumor cell invasion. Notably, second harmonic generation imaging and bioinformatic analysis of SMA-positive human HNSCC and EAC showed that collagen fiber organization correlates with poor prognosis, indicating that heterogeneity within the SMA-positive CAF population differentially impacts on survival. These results show that non-fibrogenic, SMA-positive myofibroblasts can be directly generated through induction of fibroblast senescence and suggest that senescence and myofibroblast differentiation are closely linked processes.

Molecular mechanism for the control of eukaryotic elongation factor 2 kinase by pH: role in cancer cell survival

ABSTRACT Acidification of the extracellular and/or intracellular environment is involved in many aspects of cell physiology and pathology. Eukaryotic elongation factor 2 kinase (eEF2K) is a Ca2+/calmodulin-dependent kinase that regulates translation elongation by phosphorylating and inhibiting eEF2. Here we show that extracellular acidosis elicits activation of eEF2K in vivo, leading to enhanced phosphorylation of eEF2. We identify five histidine residues in eEF2K that are crucial for the activation of eEF2K during acidosis. Three of them (H80, H87, and H94) are in its calmodulin-binding site, and their protonation appears to enhance the ability of calmodulin to activate eEF2K. The other two histidines (H227 and H230) lie in the catalytic domain of eEF2K. We also identify His108 in calmodulin as essential for activation of eEF2K. Acidification of cancer cell microenvironments is a hallmark of malignant solid tumors. Knocking down eEF2K in cancer cells attenuated the decrease in global protein synthesis when cells were cultured at acidic pH. Importantly, activation of eEF2K is linked to cancer cell survival under acidic conditions. Inhibition of eEF2K promotes cancer cell death under acidosis.

Targeting the Myofibroblastic Cancer-Associated Fibroblast Phenotype Through Inhibition of NOX4

Abstract Background Cancer-associated fibroblasts (CAFs) are tumor-promoting and correlate with poor survival in many cancers, which has led to their emergence as potential therapeutic targets. However, effective methods to manipulate these cells clinically have yet to be developed. Methods CAF accumulation and prognostic significance in head and neck cancer (oral, n = 260; oropharyngeal, n = 271), and colorectal cancer (n = 56) was analyzed using immunohistochemistry. Mechanisms regulating fibroblast-to-myofibroblast transdifferentiation were investigated in vitro using RNA interference/pharmacological inhibitors followed by polymerase chain reaction (PCR), immunoblotting, immunofluorescence, and functional assays. RNA sequencing/bioinformatics and immunohistochemistry were used to analyze NAD(P)H Oxidase-4 (NOX4) expression in different human tumors. NOX4’s role in CAF-mediated tumor progression was assessed in vitro, using CAFs from multiple tissues in Transwell and organotypic culture assays, and in vivo, using xenograft (n = 9–15 per group) and isograft (n = 6 per group) tumor models. All statistical tests were two-sided. Results Patients with moderate/high levels of myofibroblastic-CAF had a statistically significant decrease in cancer-specific survival rates in each cancer type analyzed (hazard ratios [HRs] = 1.69–7.25, 95% confidence intervals [CIs] = 1.11 to 31.30, log-rank P ≤ .01). Fibroblast-to-myofibroblast transdifferentiation was dependent on a delayed phase of intracellular reactive oxygen species, generated by NOX4, across different anatomical sites and differentiation stimuli. A statistically significant upregulation of NOX4 expression was found in multiple human cancers (P < .001), strongly correlating with myofibroblastic-CAFs (r = 0.65–0.91, adjusted P < .001). Genetic/pharmacological inhibition of NOX4 was found to revert the myofibroblastic-CAF phenotype ex vivo (54.3% decrease in α-smooth muscle actin [α-SMA], 95% CI = 10.6% to 80.9%, P = .009), prevent myofibroblastic-CAF accumulation in vivo (53.2%–79.0% decrease in α-SMA across different models, P ≤ .02) and slow tumor growth (30.6%–64.0% decrease across different models, P ≤ .04). Conclusions These data suggest that pharmacological inhibition of NOX4 may have broad applicability for stromal targeting across cancer types.

Mycobacterium tuberculosis subverts negative regulatory pathways in human macrophages to drive immunopathology

Tuberculosis remains a global pandemic and drives lung matrix destruction to transmit. Whilst pathways driving inflammatory responses in macrophages have been relatively well described, negative regulatory pathways are less well defined. We hypothesised that Mycobacterium tuberculosis (Mtb) specifically targets negative regulatory pathways to augment immunopathology. Inhibition of signalling through the PI3K/AKT/mTORC1 pathway increased matrix metalloproteinase-1 (MMP-1) gene expression and secretion, a collagenase central to TB pathogenesis, and multiple pro-inflammatory cytokines. In patients with confirmed pulmonary TB, PI3Kδ expression was absent within granulomas. Furthermore, Mtb infection suppressed PI3Kδ gene expression in macrophages. Interestingly, inhibition of the MNK pathway, downstream of pro-inflammatory p38 and ERK MAPKs, also increased MMP-1 secretion, whilst suppressing secretion of TH1 cytokines. Cross-talk between the PI3K and MNK pathways was demonstrated at the level of eIF4E phosphorylation. Mtb globally suppressed the MMP-inhibitory pathways in macrophages, reducing levels of mRNAs encoding PI3Kδ, mTORC-1 and MNK-1 via upregulation of miRNAs. Therefore, Mtb disrupts negative regulatory pathways at multiple levels in macrophages to drive a tissue-destructive phenotype that facilitates transmission.

Evaluating the effect of immune cells on the outcome of patients with mesothelioma

Background:We systematically assessed the prognostic and predictive value of infiltrating adaptive and innate immune cells in a large cohort of patients with advanced mesothelioma.Methods:A tissue microarray from 302 samples was constructed. Markers of adaptive immune response in T-cells (CD8+, FOXP3+, CD4+, CD45RO+, CD3+) and B-cells (CD20+), and of innate immune response; neutrophils (NP57+), natural killer cells (CD56+) and macrophages (CD68+) were evaluated.Results:We found that in the epithelioid tumours, high CD4+ and CD20+ counts, and low FOXP3+, CD68+ and NP57+ counts linked to better outcome. In the non-epithelioid group low CD8+ and low FOXP3+ counts were beneficial.On multivariate analysis low FOXP3+ remained independently associated with survival in both groups. In the epithelioid group additionally high CD4+, high CD20+, and low NP57+ counts were prognostic.Conclusions:Our data demonstrate for the first time, in predominately advanced disease, the association of key markers of adaptive and innate immunity with survival and the differential effect of histology. A better understanding of the immunological drivers of the different subtypes of mesothelioma will assist prognostication and disease-specific clinical decision-making.

Suppression of Hedgehog signalling promotes pro-tumourigenic integrin expression and function

Aberrant Hedgehog (Hh) signalling has been reported in a number of malignancies, particularly basal cell carcinoma (BCC) of the skin. Clinical trials of Hh inhibitors are underway in many cancers, and these have produced significant clinical benefit in BCC patients, although regrowth of new, or clinically aggressive, variants, as well as development of secondary malignancies, has been reported. αvβ6 integrin is expressed in many cancers, where it has been shown to correlate with an aggressive tumour phenotype and poor prognosis. We have previously reported αvβ6 up‐regulation in aggressive, morphoeic BCC variants, where it modulates the stromal response and induces invasion. To examine a possible link between Hh and αvβ6 function, we generated BCC models, overexpressing Gli1 in immortalized keratinocytes (NTert1, HaCaT). Unexpectedly, we found that suppressing Gli1 significantly increased αvβ6 expression. This promoted tumour cell motility and also stromal myofibroblast differentiation through integrin‐dependent TGF‐β1 activation. Gli1 inhibited αvβ6 expression by suppressing TGF‐β1‐induced Smad2/3 activation, blocking a positive feedback loop maintaining high αvβ6 levels. A similar mechanism was observed in AsPC1 pancreatic cancer cells expressing endogenous Gli1, suggesting a common mechanism across tumour types. In vitro findings were supported using human clinical samples, where we showed an inverse correlation between αvβ6 and Gli1 expression in different BCC subtypes and pancreatic cancers. In summary, we show that expression of Gli1 and αvβ6 inversely correlates in tumours in vivo, and Hh targeting up‐regulates TGF‐β1/Smad2/3‐dependent αvβ6 expression, promoting pro‐tumourigenic cell functions in vitro. These results have potential clinical significance, given the reported recurrence of BCC variants and secondary malignancies in patients treated by Hh targeting. Copyright