Transient Antiangiogenic Treatment Improves Delivery of Cytotoxic Compounds and Therapeutic Outcome in Lung Cancer

Extensive oncologic experience argues that the most efficacious applications of antiangiogenic agents rely upon a combination with cytotoxic drugs. Yet there remains a lack of clarity about how to optimize scheduling for such drug combinations. Prudent antiangiogenic therapy might transiently normalize blood vessels to improve tumor oxygenation and drug exposure. Using [15O]H2O positron emission tomography imaging in a preclinical mouse model of non–small cell lung cancer, we observed that short-term treatment with the vascular endothelial growth factor receptor/platelet-derived growth factor receptor inhibitor PTK787 licensed a transient window of improved tumor blood flow. The improvement observed was associated with a reduced leakiness from tumor vessels, consistent with induction of a vascular normalization process. Initiation of a cytotoxic treatment in this window of tumor vessel normalization resulted in increased efficacy, as illustrated by improved outcomes of erlotinib administration after initial PTK787 treatment. Notably, intermittent PTK787 treatment also facilitated long-term tumor regression. In summary, our findings offer strong evidence that short-term antiangiogenic therapy can promote a transient vessel normalization process that improves the delivery and efficacy of a targeted cytotoxic drug

Tumor VEGF:VEGFR2 autocrine feed-forward loop triggers angiogenesis in lung cancer

The molecular mechanisms that control the balance between antiangiogenic and proangiogenic factors and initiate the angiogenic switch in tumors remain poorly defined. By combining chemical genetics with multimodal imaging, we have identified an autocrine feed-forward loop in tumor cells in which tumor-derived VEGF stimulates VEGF production via VEGFR2-dependent activation of mTOR, substantially amplifying the initial proangiogenic signal. Disruption of this feed-forward loop by chemical perturbation or knockdown of VEGFR2 in tumor cells dramatically inhibited production of VEGF in vitro and in vivo. This disruption was sufficient to prevent tumor growth in vivo. In patients with lung cancer, we found that this VEGF:VEGFR2 feed-forward loop was active, as the level of VEGF/VEGFR2 binding in tumor cells was highly correlated to tumor angiogenesis. We further demonstrated that inhibition of tumor cell VEGFR2 induces feedback activation of the IRS/MAPK signaling cascade. Most strikingly, combined pharmacological inhibition of VEGFR2 (ZD6474) and MEK (PD0325901) in tumor cells resulted in dramatic tumor shrinkage, whereas monotherapy only modestly slowed tumor growth. Thus, a tumor cell-autonomous VEGF:VEGFR2 feed-forward loop provides signal amplification required for the establishment of fully angiogenic tumors in lung cancer. Interrupting this feed-forward loop switches tumor cells from an angiogenic to a proliferative phenotype that sensitizes tumor cells to MAPK inhibition

Targeting the tumor blood vessels: VEGFR2 as a Biomarker and Therapeutic Target in Non Small Cell Lung Cancer

Blood vessels transport oxygen and nutrients within the body. However, blood vessels also nourish cancer. Numerous evidences indicate uniformly towards the fact that tumors cannot grow without access to and recruitment of blood vessels, a process widely known as tumor angiogenesis. It has been well described that endothelial cell migration and proliferation is primarily regulated by VEGF-­‐A binding to its receptor VEGFR2. However molecular mechanisms that control the shift in angiogenic switch in Non Small Cell Lung Cancer remain poorly understood till date. In this PhD thesis we have identified a novel autocrine feed-­‐forward loop active in the tumor where tumor-­‐ cell autonomous VEGF:VEGFR2 feed forward loop triggers signal amplification substantially amplifying the pro-­‐angiogenic signal required for establishing fully angiogenic tumors in lung cancer. In 20% of lung cancer patients this feed forward loop was active as the level of VEGF: VEGFR2 binding in tumor cells and directly correlated with tumor angiogenesis. Disruption of this feed forward loop using inhibitors against VEGFR2 or knockdown was sufficient to prevent tumor growth in vivo. Furthermore, inhibition of tumor cell VEGFR2 induced feedback activation of the IRS/MAPK signalling pathway switching the tumor cells from an angiogenic to a proliferative phenotype. Combined pharmacological inhibition of VEGFR2 with ZD6474 and MEK with PD0325901 resulted in dramatic tumor shrinkage. We thereby propose that high expression of tumor VEGF:VEGFR2 can serve as a predictive biomarker for therapeutic efficacy of dual VEGFR2/MEK inhibition in the patients with NSCLC. Our next project was to investigate the role of VEGFR2 in the tumor microenvironment using cancer cells, which do not have a high expression of VEGFR2. In most cancers, tumor vasculature is leaky, disorganized with a chaotic morphology resulting in a hostile tumor microenvironment characterized by increased hypoxia and high interstitial fluid pressure. These abnormal vessels interfere with effective delivery of drugs and supports tumor progression and resistance to treatment. The traditional concept of using anti-­‐ angiogenic therapy to eradicate tumors by starving them from oxygen and nutrient supply by destroying existing vessels has not seen much success. One reason for this failure can be attributed to the vessel-­‐leakiness hindering homogeneous drug delivery within the tumor. Alternative strong evidences are emerging that transient application of anti-­‐angiogenic agents can normalize the aberrant tumor vasculature and that cytotoxic therapy given during this normalization window might have the best outcome. Yet there remains a lack of clarity about how to optimize scheduling such drug combinations. In this PhD thesis, we observed that short-­‐term treatment with the VEGFR / PDGFR inhibitor PTK787 or VEGFR2 inhibitor ZD6474 initiated a transient window of improved blood flow using [15O] H2O Positron Emission Tomography (PET) in a preclinical mouse model of Non Small Cell Lung Cancer. This improvement was associated with reduced vessel leakiness and enhanced pericyte coverage. Initiation of cytotoxic treatment with erlotinib during this normalization window resulted in improved treatment efficacy. Additionally intermittent PTK787 treatment also facilitated long-­‐term tumor regression. Concisely, our findings offer strong evidence that short-­‐term anti-­‐angiogenic therapy can promote transient vessel normalization that can improve the delivery and efficacy of a targeted cytotoxic drug. In summary, VEGFR2 expressed on tumor cells plays a pivotal role in driving tumor angiogenesis and the same receptor expressed in the tumor microenvironment is relevant for normalization of tumor vasculature. Hence VEGFR2 can serve as an effective therapeutic target, which may lead to eradication of tumors or survival advantage in advanced NSCLC patients in the clinic

Effectiveness of black tea extract on ROS mediated oxidative stress and other inflammatory parameters production in patients with RA in an in-vitro model system: preliminary experimental study

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Cytohesins are cytoplasmic ErbB receptor activators

Signaling by ErbB receptors requires the activation of their cytoplasmic kinase domains, which is initiated by ligand binding to the receptor ectodomains. Cytoplasmic factors contributing to the activation are unknown. Here we identify members of the cytohesin protein family as such factors. Cytohesin inhibition decreased ErbB receptor autophosphorylation and signaling, whereas cytohesin overexpression stimulated receptor activation. Monitoring epidermal growth factor receptor (EGFR) conformation by anisotropy microscopy together with cell-free reconstitution of cytohesin-dependent receptor autophosphorylation indicate that cytohesins facilitate conformational rearrangements in the intracellular domains of dimerized receptors. Consistent with cytohesins playing a prominent role in ErbB receptor signaling, we found that cytohesin overexpression correlated with EGF signaling pathway activation in human lung adenocarcinomas. Chemical inhibition of cytohesins resulted in reduced proliferation of EGFR-dependent lung cancer cells in vitro and in vivo. Our results establish cytohesins as cytoplasmic conformational activators of ErbB receptors that are of pathophysiological relevance

Non-invasive monitoring of chronic liver disease via near-infrared and shortwave-infrared imaging of endogenous lipofuscin

Monitoring the progression of non-alcoholic fatty liver disease is hindered by a lack of suitable non-invasive imaging methods. Here, we show that the endogenous pigment lipofuscin displays strong near-infrared and shortwave-infrared fluorescence when excited at 808 nm, enabling label-free imaging of liver injury in mice and the discrimination of pathological processes from normal liver processes with high specificity and sensitivity. We also show that the near-infrared and shortwave-infrared fluorescence of lipofuscin can be used to monitor the progression and regression of liver necroinflammation and fibrosis in mouse models of non-alcoholic fatty liver disease and advanced fibrosis, as well as to detect non-alcoholic steatohepatitis and cirrhosis in biopsied samples of human liver tissue.Label-free imaging of the endogenous pigment lipofuscin at near-infrared and shortwave-infrared wavelengths enables the longitudinal monitoring of liver injury in mice and in biopsied human livers

Tumor VEGF:VEGFR2 autocrine feed-forward loop triggers angiogenesis in lung cancer

The molecular mechanisms that control the balance between antiangiogenic and proangiogenic factors and initiate the angiogenic switch in tumors remain poorly defined. By combining chemical genetics with multimodal imaging, we have identified an autocrine feed-forward loop in tumor cells in which tumor-derived VEGF stimulates VEGF production via VEGFR2-dependent activation of mTOR, substantially amplifying the initial proangiogenic signal. Disruption of this feed-forward loop by chemical perturbation or knockdown of VEGFR2 in tumor cells dramatically inhibited production of VEGF in vitro and in vivo. This disruption was sufficient to prevent tumor growth in vivo. In patients with lung cancer, we found that this VEGF:VEGFR2 feed-forward loop was active, as the level of VEGF/VEGFR2 binding in tumor cells was highly correlated to tumor angiogenesis. We further demonstrated that inhibition of tumor cell VEGFR2 induces feedback activation of the IRS/MAPK signaling cascade. Most strikingly, combined pharmacological inhibition of VEGFR2 (ZD6474) and MEK (PD0325901) in tumor cells resulted in dramatic tumor shrinkage, whereas monotherapy only modestly slowed tumor growth. Thus, a tumor cell-autonomous VEGF:VEGFR2 feed-forward loop provides signal amplification required for the establishment of fully angiogenic tumors in lung cancer. Interrupting this feed-forward loop switches tumor cells from an angiogenic to a proliferative phenotype that sensitizes tumor cells to MAPK inhibition