Journal: The Journal of pathology
Fibroblasts and myofibroblasts are the key effector cells executing physiologic tissue repair leading to regeneration on one hand, and pathological fibrogenesis leading to chronic fibrosing conditions on the other. Recent studies identify the multifunctional transcription factor Early Growth Response-1(Egr-1) as an important mediator of fibroblast activation triggered by diverse stimuli. Egr-1 has potent stimulatory effects on fibrotic gene expression, and aberrant Egr-1 expression or function is associated with animal models of fibrosis and human fibrotic disorders including emphysema, pulmonary fibrosis, pulmonary hypertension and systemic sclerosis. Pharmacological suppression or genetic targeting of Egr-1 blocks fibrotic responses in vitro and ameliorates experimental fibrosis in the skin and lung. In contrast, Egr-1 appear to acts as a negative regulator of hepatic fibrosis in mouse models, suggesting a context-dependent role in fibrosis. The Egr-1-binding protein Nab2 is an endogenous inhibitor of Egr-1-mediated signaling, and abrogates the stimulation of fibrotic responses induced by transforming growth factor-ß (TGF-ß). Moreover, mice deficient in Nab2 show excessive collagen accumulation in the skin. These observations highlight a previously unsuspected fundamental physiologic function for the Egr-1/Nab2 signaling axis in regulating fibrogenesis, and suggest that Egr-1 may be a potential novel therapeutic target in human diseases complicated by fibrosis. This review summarizes recent advances in understanding the regulation and complex functional role of Egr-1 and its related proteins and inhibitors in pathological fibrosis. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
As the age of the population increases in many nations, age-related degenerative diseases pose significant socioeconomic challenges. One of the key degenerative diseases that compromise quality of life is age-related macular degeneration (AMD). AMD is a multi-faceted condition that affects the central retina, which ultimately leads to blindness in millions of people worldwide. The pathophysiology and risk factors for AMD are complex, and the symptoms manifest in multiple related but distinct forms. The ability to develop effective treatments for AMD will depend on a thorough understanding of the underlying pathophysiology, risk factors, and driver molecular pathways, as well as the ability to develop useful animal models. This review provides an overview of the aforementioned aspects in AMD. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The common preference of cancers for lactic acid-generating metabolic energy pathways has led to proposals that their reprogrammed metabolism confers growth advantages such as decreased susceptibility to hypoxic stress. Recent observations, however, suggest it generates a novel way for cancer survival. There is increasing evidence that cancers can escape immune destruction by suppressing the anticancer immune response through maintaining a relatively low pH in their micro-environment. Tumours achieve this by regulating lactic acid secretion via modification of glucose/glutamine metabolisms. We propose that the maintenance by cancers of a relatively low pH in their micro-environment, via regulation of their lactic acid secretion through selective modification of their energy metabolism, is another major mechanism by which cancers can suppress the anticancer immune response. Cancer-generated lactic acid could thus be viewed as a critical, immunosuppressive metabolite in the tumour micro-environment. This paradigm shift views cancer-generated lactic acid as a critical, regulatory immunosuppressive metabolite rather than a “waste product” and can have major impact on therapeutic strategy development.
Anti-angiogenic therapies have shown limited efficacy in the clinical management of metastatic disease, including lung metastases. Moreover, the mechanisms via which tumours resist anti-angiogenic therapies are poorly understood. Importantly, rather than utilising angiogenesis, some metastases may instead incorporate pre-existing vessels from surrounding tissue (vessel co-option). Since anti-angiogenic therapies were designed to target only new blood vessel growth, vessel co-option has been proposed as a mechanism that could drive resistance to anti-angiogenic therapy. However, vessel co-option has not been extensively studied in lung metastases, and its potential to mediate resistance to anti-angiogenic therapy in lung metastases is not established. Here we examine the mechanism of tumour vascularisation in 164 human lung metastasis specimens (composed of breast, colorectal and renal cancer lung metastasis cases). We identify four distinct histopathological growth patterns (HGPs) of lung metastasis (alveolar, interstitial, perivascular cuffing and pushing) that each vascularise via a different mechanism. In the alveolar HGP, cancer cells invade the alveolar air spaces, which facilitates the co-option of alveolar capillaries. In the interstitial HGP, cancer cells invade into the alveolar walls to co-opt alveolar capillaries. In the perivascular cuffing HGP, cancer cells grow by co-opting larger vessels of the lung. Only in the pushing HGP did the tumours vascularise by angiogenesis. Importantly, vessel co-option occurred with high frequency, being present in over 80% of the cases examined. Moreover, we provide evidence that vessel co-option mediates resistance to the anti-angiogenic drug sunitinib in preclinical lung metastasis models. Assuming that our interpretation of the data is correct, we conclude that vessel co-option in lung metastases occurs through at least three distinct mechanisms, that vessel co-option occurs frequently in lung metastases and that vessel co-option could mediate resistance to anti-angiogenic therapy in lung metastases. Novel therapies designed to target both angiogenesis and vessel co-option are therefore warranted.
Corpus-dominant lymphocytic gastritis (LyG) is characterized by a CD8(+) T-cell infiltration of the stomach epithelium due to a so far uncharacterized mechanism. While Helicobacter pylori is typically undetectable in LyG, patients respond to H. pylori antibiotic eradication therapy, suggesting a non-H. pylori microbial trigger for the disease. Comparative microbiota analysis of specimens from LyG, H. pylori gastritis and healthy controls precluded involvement of H. pylori in LyG but identified Propionibacterium acnes as a possible disease trigger. In addition, the natural killer group 2 member D (NKG2D) system and the proinflammatory cytokine IL15 are significantly upregulated in the gastric mucosa of LyG patients, and gastric epithelial cells respond to microbe-derived stimuli, including live P. acnes and the microbial products short-chain fatty acids, with induction of NKG2D ligands. In contrast, H. pylori infection does not activate or even repress NKG2D ligands. Together, our findings identify P. acnes as a possible causative agent for LyG, which is dependent on the NKG2D system and IL15 activation.
Stromal targeting for pancreatic ductal adenocarcinoma (PDAC) is rapidly becoming an attractive option, due to lack of efficacy of standard chemotherapy and increased knowledge about PDAC stroma. We postulated that the addition of stromal therapy may enhance the anti-tumour efficacy of chemotherapy. Gemcitabine and all-trans retinoic acid (ATRA) were combined in a clinically applicable regimen, to target cancer cells and pancreatic stellate cells (PSC) respectively, in 3D organotypic culture models and genetically engineered mice (LSL-Kras(G12D) (/+) ;LSL-Trp53(R172H) (/+) ;Pdx-1-Cre: KPC mice) representing the spectrum of PDAC. In two distinct sets of organotypic models as well as KPC mice, we demonstrate a reduction in cancer cell proliferation and invasion together with enhanced cancer cell apoptosis when ATRA is combined with gemcitabine, compared to vehicle or either agent alone. Simultaneously, PSC activity (as measured by deposition of extra-cellular matrix proteins such as collagen and fibronectin), and PSC invasive ability were both diminished in response to combination therapy. These effects were mediated through a range of signalling cascades (Wnt, hedgehog, retinoid and FGF) in cancer as well as stellate cells, affecting epithelial cellular functions such as epithelial-mesenchymal transition, cellular polarity and lumen formation. At the tissue level, this resulted in enhanced tumour necrosis, increased vascularity, and diminished hypoxia. Consequently, there was an overall reduction in tumour size. The enhanced effect of stromal co-targeting (ATRA) alongside chemotherapy (gemcitabine) appears to be mediated by dampening multiple signalling cascades in the tumour-stroma cross-talk, rather than ablating stroma or targeting a single pathway.
Frizzled receptors mediate Wnt ligands' signalling, which is crucially involved in regulating tissue development, differentiation and is often deregulated in cancer. In this study we found that the Wnt receptor frizzled 6 (FZD6) is frequently amplified in breast cancer, with an increased incidence in the triple negative breast cancer (TNBC) subtype. Ablation of FZD6 gene expression in mammary cancer cell lines: a) inhibited motility and invasion b) induced a more symmetric shape of organoid 3D cultures c) inhibited bone and liver metastasis in vivo. Mechanistically, FZD6 signalling is required for the assembly of the fibronectin matrix interfering with the organisation of the actin cytoskeleton. Ectopic delivery of fibronectin in FZD6-depleted, triple negative MDA-MB-231 cells rearranged the actin cytoskeleton and restored EGF-mediated invasion. In patients with localised, lymph node negative (early) breast cancer, positivity of tumour cells to FZD6 protein identified patients of with reduced distant relapse-free survival. Multivariate analysis indicated an independent prognostic significance of FZD6 expression in TNBC tumours predicting distant, but not local, relapse. We conclude that the FZD6-fibronectin-actin axis identified in our study could be exploited for drug development in highly metastatic forms of breast cancer, such as TNBC.
In osteosarcoma, a primary mesenchymal bone cancer occurring predominantly in younger patients, invasive tumor growth leads to extensive bone destruction. This process is insufficiently understood, cannot be efficiently counteracted and calls for novel means of treatment. The endocytic collagen receptor, uPARAP/Endo180, is expressed on various mesenchymal cell types and is involved in bone matrix turnover during normal bone growth. Human osteosarcoma specimens showed strong expression of this receptor on tumor cells, along with the collagenolytic metalloprotease, MT1-MMP. In advanced tumors with ongoing bone degeneration, sarcoma cells positive for these proteins formed a contiguous layer aligned with the degradation zones. Remarkably, osteoclasts were scarce or absent from these regions and quantitative analysis revealed that this scarcity marked a strong contrast between osteosarcoma and bone metastases of carcinoma origin. This opened the possibility that sarcoma cells might directly mediate bone degeneration. To examine this question, we utilized a syngeneic, osteolytic bone tumor model with transplanted NCTC-2472 sarcoma cells. When analyzed in vitro, these cells were capable of degrading the protein component of surface-labeled bone slices in a process dependent on MMP activity and uPARAP/Endo180. Systemic treatment of the sarcoma-inoculated mice with a mouse monoclonal antibody that blocks murine uPARAP/Endo180 led to a strong reduction of bone destruction. Our findings identify sarcoma cell-resident uPARAP/Endo180 as a central player in the bone degeneration of advanced tumors, possibly following an osteoclast-mediated attack on bone in the early tumor stage. This points to uPARAP/Endo180 as a promising therapeutic target in osteosarcoma with particular prospects for improved neoadjuvant therapy.
We present the first analytical approach to demonstrate the in situ imaging of metabolites from formalin-fixed paraffin-embedded (FFPE) human tissue samples. Using high-resolution Matrix-Assisted Laser Desorption/Ionization Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry Imaging (MALDI-FT-ICR MSI), we conducted a proof of principle experiment comparing metabolite measurements from FFPE and fresh frozen tissue sections, and found an overlap of 72% amongst 1700 m/z species. In particular, we observed conservation of biomedically relevant information at the metabolite level in FFPE tissues. In biomedical applications, we analysed tissues from 350 different cancer patients, and were able to discriminate between normal and tumour tissues, and different tumours from the same organ, and found an independent prognostic factor for patient survival. This study demonstrates the ability to measure metabolites in FFPE tissues using MALDI-FT-ICR MSI, which can then be assigned to histology and clinical parameters. Our approach is a major technical, histochemical and clinicopathological advance that highlights the potential for investigating diseases in archived FFPE tissues.
Idiopathic pulmonary fibrosis is a severe chronic lung disease with a high mortality rate. Excessive TGF-β signaling is recognized as a central player in lung fibrosis. However, the related mechanisms remain unclear. Herein we used a novel Tbx4 lung enhancer-driven Tet-On transgenic system to inhibit TGF-β signaling in mouse lung resident mesenchymal cells at different stages of bleomycin-induced fibrosis by conditionally knocking out TGF-β receptor II or expressing a dominant-negative TGF-β receptor II. Abrogation of mesenchymal TGF-β signaling markedly attenuated bleomycin-induced fibrotic pathology, which was independent of altered early inflammation. Furthermore, a novel TGF-β downstream target gene P4HA3 (an α-subunit of collagen prolyl hydroxylase) was identified, and its expression was significantly increased in fibroblastic foci of both bleomycin-induced fibrotic mouse lungs and idiopathic pulmonary fibrosis patients' lungs. The relationship between activated TGF-β signaling, upregulation of P4HA3, as well as increased hydroxyproline/collagen production was further verified in cultured lung fibroblasts. Moreover, inhibition of collagen prolyl hydroxylase by pyridine-2,5-dicarboxylate attenuated both TGF-β-stimulated collagen production in cultured fibroblasts and bleomycin-induced mouse lung fibrosis. These data indicate that increased expression and activity of collagen prolyl hydroxylase is one of the important mechanisms underlying TGF-β-mediated profibrotic effects. Inhibition of collagen prolyl hydroxylase may be a new promising approach for preventing and treating pulmonary fibrosis.