MiR-200c reprograms fibroblasts to recapitulate the phenotype of CAFs in breast cancer progression.

Mesenchymal-epithelial plasticity driving cancer progression in cancer-associated fibroblasts (CAFs) is undetermined. This work identifies a subgroup of CAFs in human breast cancer exhibiting mesenchymal-to-epithelial transition (MET) or epithelial-like profile with high miR-200c expression. MiR-200c overexpression in fibroblasts is sufficient to drive breast cancer aggressiveness. Oxidative stress in the tumor microenvironment induces miR-200c by DNA demethylation. Proteomics, RNA-seq and functional analyses reveal that miR-200c is a novel positive regulator of NFκB-HIF signaling via COMMD1 downregulation and stimulates pro-tumorigenic inflammation and glycolysis. Reprogramming fibroblasts toward MET via miR-200c reduces stemness and induces a senescent phenotype. This pro-tumorigenic profile in CAFs fosters carcinoma cell resistance to apoptosis, proliferation and immunosuppression, leading to primary tumor growth, metastases, and resistance to immuno-chemotherapy. Conversely, miR-200c inhibition in fibroblasts restrains tumor growth with abated oxidative stress and an anti-tumorigenic immune environment. This work determines the mechanisms by which MET in CAFs via miR-200c transcriptional enrichment with DNA demethylation triggered by oxidative stress promotes cancer progression. CAFs undergoing MET trans-differentiation and senescence coordinate heterotypic signaling that may be targeted as an anti-cancer strategy.

TP53 Induced Glycolysis and Apoptosis Regulator and Monocarboxylate Transporter 4 drive metabolic reprogramming with c-MYC and NFkB activation in breast cancer.

Breast cancer is composed of metabolically coupled cellular compartments with upregulation of TP53 Induced Glycolysis and Apoptosis Regulator (TIGAR) in carcinoma cells and loss of caveolin 1 (CAV1) with upregulation of monocarboxylate transporter 4 (MCT4) in fibroblasts. The mechanisms that drive metabolic coupling are poorly characterized. The effects of TIGAR on fibroblast CAV1 and MCT4 expression and breast cancer aggressiveness was studied using coculture and conditioned media systems and in-vivo. Also, the role of cytokines in promoting tumor metabolic coupling via MCT4 on cancer aggressiveness was studied. TIGAR downregulation in breast carcinoma cells reduces tumor growth. TIGAR overexpression in carcinoma cells drives MCT4 expression and NFkB activation in fibroblasts. IL6 and TGFB drive TIGAR upregulation in carcinoma cells, reduce CAV1 and increase MCT4 expression in fibroblasts. Tumor growth is abrogated in the presence of MCT4 knockout fibroblasts and environment. We discovered coregulation of c-MYC and TIGAR in carcinoma cells driven by lactate. Metabolic coupling primes the tumor microenvironment allowing for production, uptake and utilization of lactate. In sum, aggressive breast cancer is dependent on metabolic coupling.

Assessment of Patients with Neuromyelitis Optica Spectrum Disorder Using the EQ-5D.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disease characterized by unpredictable attacks of the optic nerves and spinal cord that cause neurologic deficits, including weakness, numbness, bowel/bladder dysfunction, and pain and reduced vision and can ultimately lead to blindness and paralysis. We assessed the effects of NMOSD on quality of life. METHODS: Adult patients with NMOSD treated at a US academic neurology clinic completed the EQ-5D and several other measures of functional status and quality of life. The EQ-5D scores and correlations across measures were evaluated, and scores were compared with those of patients with multiple sclerosis and US norms. RESULTS: Twenty-one patients (90% women; mean age, 42.8 years; mean disease duration, 8.2 years) were included. The mean EQ-5D score was 0.74. Most patients reported at least some problems with mobility, pain/discomfort, usual activities, and/or anxiety/depression. Greater proportions of patients reported moderate or severe problems with mobility and pain/discomfort than they did with self-care, usual activities, or anxiety/depression. In a multivariate model, only the Brief Pain Inventory was a significant independent predictor of overall EQ-5D score. CONCLUSIONS: Neuromyelitis optica spectrum disorder has a substantial effect on multiple domains of quality of life. Pain seems to be among the primary drivers of the EQ-5D scores in NMOSD.

The age of blood in pediatric intensive care units (ABC PICU): study protocol for a randomized controlled trial.

BACKGROUND: The "Age of Blood in Children in Pediatric Intensive Care Unit" (ABC PICU) study is a randomized controlled trial (RCT) that aims to determine if red blood cell (RBC) unit storage age affects outcomes in critically ill children. While RBCs can be stored for up to 42 days in additive solutions, their efficacy and safety after long-term storage have been challenged. Preclinical and clinical observational evidence suggests loss of efficacy and lack of safety of older RBC units, especially in more vulnerable populations such as critically ill children. Because there is a belief that shorter storage will improve outcomes, some physicians and institutions systematically transfuse fresh RBCs to children. Conversely, the standard practice of blood banks is to deliver the oldest available RBC unit (first-in, first-out policy) in order to decrease wastage. METHODS/DESIGN: The ABC PICU study, is a double-blind superiority trial comparing the development of "New or Progressive Multiple Organ Dysfunction Syndrome" (NPMODS) in 1538 critically ill children randomized to either transfusion with RBCs stored for ≤ 7 days or to standard-issue RBCs (oldest in inventory). Patients are being recruited from 52 centers in the US, Canada, France, Italy, and Israel. DISCUSSION: The ABC PICU study should have significant implications for blood procurement services. A relative risk reduction of 33% is postulated in the short-storage arm. If a difference is found, this will indicate that fresher RBCs do improve outcomes in the pediatric intensive care unit population and would justify that use in critically ill children. If no difference is found, this will reassure clinicians and transfusion medicine specialists regarding the safety of the current system of allocating the oldest RBC unit in inventory and will discourage clinicians from preferentially requesting fresher blood for critically ill children. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT01977547 . Registered on 6 November 2013.

Mitochondrial and glycolytic metabolic compartmentalization in diffuse large B-cell lymphoma.

Metabolic heterogeneity between neoplastic cells and surrounding stroma has been described in several epithelial malignancies; however, the metabolic phenotypes of neoplastic lymphocytes and neighboring stroma in diffuse large B-cell lymphoma (DLBCL) is unknown. We investigated the metabolic phenotypes of human DLBCL tumors by using immunohistochemical markers of glycolytic and mitochondrial oxidative phosphorylation (OXPHOS) metabolism. The lactate importer MCT4 is a marker of glycolysis, whereas the lactate importer MCT1 and TOMM20 are markers of OXPHOS metabolism. Staining patterns were assessed in 33 DLBCL samples as well as 18 control samples (non-neoplastic lymph nodes). TOMM20 and MCT1 were highly expressed in neoplastic lymphocytes, indicating an OXPHOS phenotype, whereas non-neoplastic lymphocytes in the control samples did not express these markers. Stromal cells in DLBCL samples strongly expressed MCT4, displaying a glycolytic phenotype, a feature not seen in stromal elements of non-neoplastic lymphatic tissue. Furthermore, the differential expression of lactate exporters (MCT4) on tumor-associated stroma and lactate importers (MCT1) on neoplastic lymphocytes support the hypothesis that neoplastic cells are metabolically linked to the stroma likely via mutually beneficial reprogramming. MCT4 is a marker of tumor-associated stroma in neoplastic tissue. Our findings suggest that disruption of neoplastic-stromal cell metabolic heterogeneity including MCT1 and MCT4 blockade should be studied to determine if it could represent a novel treatment target in DLBCL.

TP53-inducible Glycolysis and Apoptosis Regulator (TIGAR) Metabolically Reprograms Carcinoma and Stromal Cells in Breast Cancer.

A subgroup of breast cancers has several metabolic compartments. The mechanisms by which metabolic compartmentalization develop in tumors are poorly characterized. TP53 inducible glycolysis and apoptosis regulator (TIGAR) is a bisphosphatase that reduces glycolysis and is highly expressed in carcinoma cells in the majority of human breast cancers. Hence we set out to determine the effects of TIGAR expression on breast carcinoma and fibroblast glycolytic phenotype and tumor growth. The overexpression of this bisphosphatase in carcinoma cells induces expression of enzymes and transporters involved in the catabolism of lactate and glutamine. Carcinoma cells overexpressing TIGAR have higher oxygen consumption rates and ATP levels when exposed to glutamine, lactate, or the combination of glutamine and lactate. Coculture of TIGAR overexpressing carcinoma cells and fibroblasts compared with control cocultures induce more pronounced glycolytic differences between carcinoma and fibroblast cells. Carcinoma cells overexpressing TIGAR have reduced glucose uptake and lactate production. Conversely, fibroblasts in coculture with TIGAR overexpressing carcinoma cells induce HIF (hypoxia-inducible factor) activation with increased glucose uptake, increased 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3), and lactate dehydrogenase-A expression. We also studied the effect of this enzyme on tumor growth. TIGAR overexpression in carcinoma cells increases tumor growth in vivo with increased proliferation rates. However, a catalytically inactive variant of TIGAR did not induce tumor growth. Therefore, TIGAR expression in breast carcinoma cells promotes metabolic compartmentalization and tumor growth with a mitochondrial metabolic phenotype with lactate and glutamine catabolism. Targeting TIGAR warrants consideration as a potential therapy for breast cancer.

"The Immune Conundrum": Acquired Hemophilia A, Immune Thrombocytopenia, and Neutropenia in a Patient with Pancreatic Cancer.

Background: Malignancy-associated bleeding can pose diagnostic dilemmas. We report a unique case of paraneoplastic acquired hemophilia A (AHA), immune thrombocytopenia (ITP), and immune neutropenia in a patient with pancreatic adenocarcinoma. Case Presentation: A 66-year-old male with newly diagnosed pancreatic cancer and normal preoperative hematological evaluation was taken to the operating room for pancreaticoduodenectomy. The operation was aborted due to empyema of the gall bladder, cholangitis, and local extent of disease. Postoperatively, the patient developed bleeding diatheses with mucocutaneous and intra-abdominal bleeding and a prolonged activated partial thromboplastin time. Evaluation revealed high-titer factor VIII inhibitor confirming AHA. Management with bypassing agents such as recombinant activated factor VII, factor VIII inhibitor bypassing activity, and immunosuppression with steroids, cyclophosphamide, and rituximab achieved remission in 2 months. ITP developed after achieving normal factor VIII levels, which was managed with intravenous immunoglobulin. Neutropenia was detected before initiation of chemotherapy and was managed with granulocyte-colony stimulating factor. Conclusion: These unique challenges posed by paraneoplastic hematological syndromes warrant the need for astute clinical judgment and multidisciplinary collaboration for effective management.

Communicating the parameter uncertainty in the IQWiG efficiency frontier to decision-makers.

The Institute for Quality and Efficiency in Health Care (IQWiG) developed-in a consultation process with an international expert panel-the efficiency frontier (EF) approach to satisfy a range of legal requirements for economic evaluation in Germany's statutory health insurance system. The EF approach is distinctly different from other health economic approaches. Here, we evaluate established tools for assessing and communicating parameter uncertainty in terms of their applicability to the EF approach. Among these are tools that perform the following: (i) graphically display overall uncertainty within the IQWiG EF (scatter plots, confidence bands, and contour plots) and (ii) communicate the uncertainty around the reimbursable price. We found that, within the EF approach, most established plots were not always easy to interpret. Hence, we propose the use of price reimbursement acceptability curves-a modification of the well-known cost-effectiveness acceptability curves. Furthermore, it emerges that the net monetary benefit allows an intuitive interpretation of parameter uncertainty within the EF approach. This research closes a gap for handling uncertainty in the economic evaluation approach of the IQWiG methods when using the EF. However, the precise consequences of uncertainty when determining prices are yet to be defined.

Erythropoietin levels in patients with sickle cell disease do not correlate with known inducers of erythropoietin.

Previous studies have suggested that erythropoietin (Epo) levels may be inappropriately low in patients with sickle cell disease compared to the extent of the related anemia they demonstrate. Here, we evaluate Epo level vs. renal function, oxygenation, and markers of inflammation for patients treated for sickle cell disease at our institution. Blood was drawn from 54 patients with sickle cell disease during routine visits to the outpatient hematology office and analyzed for hemoglobin (Hb) level, Epo, markers of inflammation, oxygenation, and renal function. Erythropoietin levels were lower than expected for patients with sickle cell disease, compared to the degree of anemia demonstrated in these patients. In addition, a correlation between Hb level and Epo was not consistently observed. Higher Epo levels were seen in patients receiving hydroxyurea (HU), but no correlation with oxygenation, hemolysis, renal function, or inflammation was observed.

Assessing the value of healthcare interventions using multi-criteria decision analysis: a review of the literature.

The objective of this study is to support those undertaking a multi-criteria decision analysis (MCDA) by reviewing the approaches adopted in healthcare MCDAs to date, how these varied with the objective of the study, and the lessons learned from this experience. Searches of EMBASE and MEDLINE identified 40 studies that provided 41 examples of MCDA in healthcare. Data were extracted on the objective of the study, methods employed, and decision makers' and study authors' reflections on the advantages and disadvantages of the methods. The recent interest in MCDA in healthcare is mirrored in an increase in the application of MCDA to evaluate healthcare interventions. Of the studies identified, the first was published in 1990, but more than half were published since 2011. They were undertaken in 18 different countries, and were designed to support investment (coverage and reimbursement), authorization, prescription, and research funding allocation decisions. Many intervention types were assessed: pharmaceuticals, public health interventions, screening, surgical interventions, and devices. Most used the value measurement approach and scored performance using predefined scales. Beyond these similarities, a diversity of different approaches were adopted, with only limited correspondence between the approach and the type of decision or product. Decision makers consulted as part of these studies, as well as the authors of the studies are positive about the potential of MCDA to improve decision making. Further work is required, however, to develop guidance for those undertaking MCDA.

Control of Glycolytic Flux by AMP-Activated Protein Kinase in Tumor Cells Adapted to Low pH.

Tumor cells grow in nutrient- and oxygen-deprived microenvironments and adapt to the suboptimal growth conditions by altering their metabolic pathways. This adaptation process commonly results in a tumor phenotype that displays a high rate of aerobic glycolysis and aggressive tumor characteristics. The glucose regulatory molecule, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), is a bifunctional enzyme that is central to glycolytic flux and is downstream of the metabolic stress sensor AMP-activated protein kinase (AMPK), which has been suggested to modulate glycolysis and possibly activate isoforms of PFKFB, specifically PFKFB3 expressed in tumor cells. Our results demonstrated that long-term low pH exposure induced AMPK activation, which resulted in the up-regulation of PFKFB3 and an increase in its serine residue phosphorylation. Pharmacologic activation of AMPK resulted in an increase in PFKFB3 as well as an increase in glucose consumption, whereas in contrast, inhibition of AMPK resulted in the down-regulation of PFKFB3 and decreased glycolysis. PFKFB3 overexpression in DB-1 tumor cells induced a high rate of glycolysis and inhibited oxygen consumption, confirming its role in controlling glycolytic flux. These results show that low pH is a physiological stress that can promote a glycolytic phenotype commonly associated with tumorigenesis. The implications are that the tumor microenviroment contributes to tumor growth and treatment resistance.

The autophagic tumor stroma model of cancer or "battery-operated tumor growth": A simple solution to the autophagy paradox.

The role of autophagy in tumorigenesis is controversial. Both autophagy inhibitors (chloroquine) and autophagy promoters (rapamycin) block tumorigenesis by unknown mechanism(s). This is called the "Autophagy Paradox". We have recently reported a simple solution to this paradox. We demonstrated that epithelial cancer cells use oxidative stress to induce autophagy in the tumor microenvironment. As a consequence, the autophagic tumor stroma generates recycled nutrients that can then be used as chemical building blocks by anabolic epithelial cancer cells. This model results in a net energy transfer from the tumor stroma to epithelial cancer cells (an energy imbalance), thereby promoting tumor growth. This net energy transfer is both unilateral and vectorial, from the tumor stroma to the epithelial cancer cells, representing a true host-parasite relationship. We have termed this new paradigm "The Autophagic Tumor Stroma Model of Cancer Cell Metabolism" or "Battery-Operated Tumor Growth". In this sense, autophagy in the tumor stroma serves as a "battery" to fuel tumor growth, progression and metastasis, independently of angiogenesis. Using this model, the systemic induction of autophagy will prevent epithelial cancer cells from using recycled nutrients, while the systemic inhibiton of autophagy will prevent stromal cells from producing recycled nutrients-both effectively "starving" cancer cells. We discuss the idea that tumor cells could become resistant to the systemic induction of autophagy, by the upregulation of natural endogenous autophagy inhibitors in cancer cells. Alternatively, tumor cells could also become resistant to the systemic induction of autophagy, by the genetic silencing/deletion of pro-autophagic molecules, such as Beclin1. If autophagy resistance develops in cancer cells, then the systemic inhibition of autophagy would provide a therapeutic solution to this type of drug resistance, as it would still target autophagy in the tumor stroma. As such, an anti-cancer therapy that combines the alternating use of both autophagy promoters and autophagy inhibitors would be expected to prevent the onset of drug resistance. We also discuss why anti-angiogenic therapy has been found to promote tumor recurrence, progression and metastasis. More specifically, anti-angiogenic therapy would induce autophagy in the tumor stroma via the induction of stromal hypoxia, thereby converting a non-aggressive tumor type to a "lethal" aggressive tumor phenotype. Thus, uncoupling the metabolic parasitic relationship between cancer cells and an autophagic tumor stroma may hold great promise for anti-cancer therapy. Finally, we believe that autophagy in the tumor stroma is the local microscopic counterpart of systemic wasting (cancer-associated cachexia), which is associated with advanced and metastatic cancers. Cachexia in cancer patients is not due to decreased energy intake, but instead involves an increased basal metabolic rate and increased energy expenditures, resulting in a negative energy balance. Importantly, when tumors were surgically excised, this increased metabolic rate returned to normal levels. This view of cachexia, resulting in energy transfer to the tumor, is consistent with our hypothesis. So, cancer-associated cachexia may start locally as stromal autophagy, and then spread systemically. As such, stromal autophagy may be the requisite precursor of systemic cancer-associated cachexia.

The global pertussis initiative: Meeting report from the Regional Latin America Meeting, Costa Rica, 5-6 December, 2008.

Pertussis remains endemic across the world, with an estimated 279,000 deaths in 2002, the majority in infants under 1 year of age. Worldwide epidemiologic data indicates increasing infection rates in older children and adults, which act as a source of infection to young infants. The Global Pertussis Initiative (GPI) is an expert scientific forum, which has published consensus recommendations for the monitoring, prevention, and treatment of the disease. This paper reports the proceedings of a regional meeting, held in Costa Rica in December 2008. The meeting gathered information on regional epidemiological, diagnostic capabilities and the ability to introduce GPI recommended vaccine strategies in Latin America. The capacity of Latin American countries to conduct vaccination programs is high and there is considerable government support. Whole-cell pertussis vaccines are used across Latin America, which appear to be quite effective. A 4-dose schedule is typically used (2, 4, 6, and 18 months), and a booster given at 4 to 6 years of age, with coverage often above 90%, but with regions of low coverage due to political and geographical difficulties. Adequate surveillance is lacking in many countries, giving insufficient data to guide vaccination policy. Improvements are being made, with countries such as Costa Rica, Panama, and Argentina introducing polymerase chain reaction (PCR) diagnosis. Those countries that do not currently use a preschool booster should launch one. Implementing vaccination programs in adolescents and/or adults to reduce exposure to infants would be beneficial and possible in most countries, given their current infrastructure.

HIF1-alpha functions as a tumor promoter in cancer associated fibroblasts, and as a tumor suppressor in breast cancer cells: Autophagy drives compartment-specific oncogenesis.

Our recent studies have mechanistically implicated a loss of stromal Cav-1 expression and HIF1-alpha-activation in driving the cancer-associated fibroblast phenotype, through the paracrine production of nutrients via autophagy and aerobic glycolysis. However, it remains unknown if HIF1a-activation is sufficient to confer the cancer-associated fibroblast phenotype. To test this hypothesis directly, we stably-expressed activated HIF1a in fibroblasts and then examined their ability to promote tumor growth using a xenograft model employing human breast cancer cells (MDA-MB-231). Fibroblasts harboring activated HIF1a showed a dramatic reduction in Cav-1 levels and a shift towards aerobic glycolysis, as evidenced by a loss of mitochondrial activity, and an increase in lactate production. Activated HIF1a also induced BNIP3 and BNIP3L expression, markers for the autophagic destruction of mitochondria. Most importantly, fibroblasts expressing activated HIF1a increased tumor mass by ∼2-fold and tumor volume by ∼3-fold, without a significant increase in tumor angiogenesis. In this context, HIF1a also induced an increase in the lymph node metastasis of cancer cells. Similar results were obtained by driving NFκB activation in fibroblasts, another inducer of autophagy. Thus, activated HIF1a is sufficient to functionally confer the cancer-associated fibroblast phenotype. It is also known that HIF1a expression is required for the induction of autophagy in cancer cells. As such, we next directly expressed activated HIF1a in MDA-MB-231 cells and assessed its effect on tumor growth via xenograft analysis. Surprisingly, activated HIF1a in cancer cells dramatically suppressed tumor growth, resulting in a 2-fold reduction in tumor mass and a 3-fold reduction in tumor volume. We conclude that HIF1a activation in different cell types can either promote or repress tumorigenesis. Based on these studies, we suggest that autophagy in cancer-associated fibroblasts promotes tumor growth via the paracrine production of recycled nutrients, which can directly "feed" cancer cells. Conversely, autophagy in cancer cells represses tumor growth via their "self-digestion". Thus, we should consider that the activities of various known oncogenes and tumor-suppressors may be compartment and cell-type specific, and are not necessarily an intrinsic property of the molecule itself. As such, other "classic" oncogenes and tumor suppressors will have to be re-evaluated to determine their compartment specific effects on tumor growth and metastasis. Lastly, our results provide direct experimental support for the recently proposed "Autophagic Tumor Stroma Model of Cancer".

Discrete event simulation: the preferred technique for health economic evaluations?

OBJECTIVES: To argue that discrete event simulation should be preferred to cohort Markov models for economic evaluations in health care. METHODS: The basis for the modeling techniques is reviewed. For many health-care decisions, existing data are insufficient to fully inform them, necessitating the use of modeling to estimate the consequences that are relevant to decision-makers. These models must reflect what is known about the problem at a level of detail sufficient to inform the questions. Oversimplification will result in estimates that are not only inaccurate, but potentially misleading. RESULTS: Markov cohort models, though currently popular, have so many limitations and inherent assumptions that they are inadequate to inform most health-care decisions. An event-based individual simulation offers an alternative much better suited to the problem. A properly designed discrete event simulation provides more accurate, relevant estimates without being computationally prohibitive. It does require more data and may be a challenge to convey transparently, but these are necessary trade-offs to provide meaningful and valid results. CONCLUSION: In our opinion, discrete event simulation should be the preferred technique for health economic evaluations today.

Autophagy in cancer associated fibroblasts promotes tumor cell survival: Role of hypoxia, HIF1 induction and NFκB activation in the tumor stromal microenvironment.

Recently, using a co-culture system, we demonstrated that MCF7 epithelial cancer cells induce oxidative stress in adjacent cancer-associated fibroblasts, resulting in the autophagic/lysosomal degradation of stromal caveolin-1 (Cav-1). However, the detailed signaling mechanism(s) underlying this process remain largely unknown. Here, we show that hypoxia is sufficient to induce the autophagic degradation of Cav-1 in stromal fibroblasts, which is blocked by the lysosomal inhibitor chloroquine. Concomitant with the hypoxia-induced degradation of Cav-1, we see the upregulation of a number of well-established autophagy/mitophagy markers, namely LC3, ATG16L, BNIP3, BNIP3L, HIF-1α and NFκB. In addition, pharmacological activation of HIF-1α drives Cav-1 degradation, while pharmacological inactivation of HIF-1 prevents the downregulation of Cav-1. Similarly, pharmacological inactivation of NFκB--another inducer of autophagy-prevents Cav-1 degradation. Moreover, treatment with an inhibitor of glutathione synthase, namely BSO, which induces oxidative stress via depletion of the reduced glutathione pool, is sufficient to induce the autophagic degradation of Cav-1. Thus, it appears that oxidative stress mediated induction of HIF1- and NFκB-activation in fibroblasts drives the autophagic degradation of Cav-1. In direct support of this hypothesis, we show that MCF7 cancer cells activate HIF-1α- and NFκB-driven luciferase reporters in adjacent cancer-associated fibroblasts, via a paracrine mechanism. Consistent with these findings, acute knock-down of Cav-1 in stromal fibroblasts, using an siRNA approach, is indeed sufficient to induce autophagy, with the upregulation of both lysosomal and mitophagy markers. How does the loss of stromal Cav-1 and the induction of stromal autophagy affect cancer cell survival? Interestingly, we show that a loss of Cav-1 in stromal fibroblasts protects adjacent cancer cells against apoptotic cell death. Thus, autophagic cancer-associated fibroblasts, in addition to providing recycled nutrients for cancer cell metabolism, also play a protective role in preventing the death of adjacent epithelial cancer cells. We demonstrate that cancer-associated fibroblasts upregulate the expression of TIGAR in adjacent epithelial cancer cells, thereby conferring resistance to apoptosis and autophagy. Finally, the mammary fat pads derived from Cav-1 (-/-) null mice show a hypoxia-like response in vivo, with the upregulation of autophagy markers, such as LC3 and BNIP3L. Taken together, our results provide direct support for the "Autophagic Tumor Stroma Model of Cancer Metabolism", and explain the exceptional prognostic value of a loss of stromal Cav-1 in cancer patients. Thus, a loss of stromal fibroblast Cav-1 is a biomarker for chronic hypoxia, oxidative stress and autophagy in the tumor microenvironment, consistent with its ability to predict early tumor recurrence, lymph node metastasis and tamoxifen-resistance in human breast cancers. Our results imply that cancer patients lacking stromal Cav-1 should benefit from HIF-inhibitors, NFκB-inhibitors, anti-oxidant therapies, as well as autophagy/lysosomal inhibitors. These complementary targeted therapies could be administered either individually or in combination, to prevent the onset of autophagy in the tumor stromal compartment, which results in a "lethal" tumor microenvironment.