Sorena Nadaf

Production of vascular endothelial growth factor by human tumors inhibits the functional maturation of dendritic cells

Inadequate presentation of tumor antigens by host professional antigen–presenting cells (APCs), including dendritic cells (DCs), is one potential mechanism for the escape of tumors from the host immune system. Here, we show that human cancer cell lines release a soluble factor or factors that dramatically affect DC maturation from precursors without affecting the function of relatively mature DCs. One factor responsible for these effects was identified as vascular endothelial growth factor (VEGF). Thus, VEGF may play a broader role in the pathogenesis of cancer than was previously thought, and therapeutic blockade of VEGF action may improve prospects for immunotherapy as well as inhibit tumor neovasculature.

Proteomic patterns of tumour subsets in non-small-cell lung cancer.

BACKGROUND Proteomics-based approaches complement the genome initiatives and may be the next step in attempts to understand the biology of cancer. We used matrix-assisted laser desorption/ionisation mass spectrometry directly from 1-mm regions of single frozen tissue sections for profiling of protein expression from surgically resected tissues to classify lung tumours. METHODS Proteomic spectra were obtained and aligned from 79 lung tumours and 14 normal lung tissues. We built a class-prediction model with the proteomic patterns in a training cohort of 42 lung tumours and eight normal lung samples, and assessed their statistical significance. We then applied this model to a blinded test cohort, including 37 lung tumours and six normal lung samples, to estimate the misclassification rate. FINDINGS We obtained more than 1600 protein peaks from histologically selected 1 mm diameter regions of single frozen sections from each tissue. Class-prediction models based on differentially expressed peaks enabled us to perfectly classify lung cancer histologies, distinguish primary tumours from metastases to the lung from other sites, and classify nodal involvement with 85% accuracy in the training cohort. This model nearly perfectly classified samples in the independent blinded test cohort. We also obtained a proteomic pattern comprised of 15 distinct mass spectrometry peaks that distinguished between patients with resected non-small-cell lung cancer who had poor prognosis (median survival 6 months, n=25) and those who had good prognosis (median survival 33 months, n=41, p<0.0001). INTERPRETATION Proteomic patterns obtained directly from small amounts of fresh frozen lung-tumour tissue could be used to accurately classify and predict histological groups as well as nodal involvement and survival in resected non-small-cell lung cancer.

Differential Roles of Vascular Endothelial Growth Factor Receptors 1 and 2 in Dendritic Cell Differentiation

Impaired Ag-presenting function in dendritic cells (DCs) due to abnormal differentiation is an important mechanism of tumor escape from immune control. A major role for vascular endothelial growth factor (VEGF) and its receptors, VEGFR1/Flt-1 and VEGFR2/KDR/Flk-1, has been documented in hemopoietic development. To study the roles of each of these receptors in DC differentiation, we used an in vitro system of myeloid DC differentiation from murine embryonic stem cells. Exposure of wild-type, VEGFR1−/−, or VEGFR2−/− embryonic stem cells to exogenous VEGF or the VEGFR1-specific ligand, placental growth factor, revealed distinct roles of VEGF receptors. VEGFR1 is the primary mediator of the VEGF inhibition of DC maturation, whereas VEGFR2 tyrosine kinase signaling is essential for early hemopoietic differentiation, but only marginally affects final DC maturation. SU5416, a VEGF receptor tyrosine kinase inhibitor, only partially rescued the mature DC phenotype in the presence of VEGF, suggesting the involvement of both tyrosine kinase-dependent and independent inhibitory mechanisms. VEGFR1 signaling was sufficient for blocking NF-κB activation in bone marrow hemopoietic progenitor cells. VEGF and placental growth factor affect the early stages of myeloid/DC differentiation. The data suggest that therapeutic strategies attempting to reverse the immunosuppressive effects of VEGF in cancer patients might be more effective if they specifically targeted VEGFR1.

Thioredoxin-1 Modulates Transcription of Cyclooxygenase-2 via Hypoxia-Inducible Factor-1α in Non–Small Cell Lung Cancer

Hypoxic induction of gene expression occurs mainly via the hypoxia-inducible factor-1 (HIF-1) transcription factor and is a critical step in tumor growth. Cyclooxygenase-2 (COX-2) is commonly overexpressed in non-small cell lung cancer (NSCLC). In this study, we sought to determine the role of HIF-1 in the induction of COX-2 expression during hypoxia. Through sequence comparison of hypoxia-responsive genes, COX-2 promoter deletion analysis, and site-directed mutagenesis, we identified a hypoxia-responsive element within the COX-2 promoter that interacts with HIF-1alpha and underlies the mechanism of hypoxic activation of COX-2 in lung cancer cells. Proteomic analysis of NSCLC identified thioredoxin-1 as a redox protein overexpressed in NSCLC correlated with poor prognosis. We also show that thioredoxin-1 stabilizes HIF-1alpha to induce hypoxia-responsive genes under normoxic conditions. Our results identify two new mechanisms for regulation of COX-2 expression in NSCLC.

H1° histone and differentiation of dendritic cells. A molecular target for tumor‐derived factors

Dendritic cells (DC) play a central role in antitumor immune responses. Abnormal differentiation of DC and their inability to stimulate T cells are important factors in tumor escape from immune‐system control. However, the mechanisms of this process remain elusive. Here, we have described one possible molecular mechanism that involves replacement linker histone H1°. A close association between expression of H1° and DC differentiation in vitro has been found. DC production in H1°‐deficient mice was decreased significantly, whereas generation and function of macrophages, granulocytes, and lymphocytes appear to be normal. However, these mice had a significantly reduced response to vaccination with antigens. Tumor‐derived factors considerably reduced h1° expression in hematopoietic progenitor cells. We have demonstrated that transcription factor NF‐κB is involved actively in regulation of h1°. Thus, H1° histone may be an important factor in normal DC differentiation. Tumor‐derived factors may inhibit DC differentiation by affecting H1° expression.

Combination therapy with conditionally replicating adenovirus and replication defective adenovirus.

Low gene transfer rate is the most substantial hurdle in the practical application of gene therapy. One strategy to improve transfer efficiency is the use of a conditionally replicating adenovirus (CRAD) that can selectively replicate in tumor cells. We hypothesized that conventional E1-deleted adenoviruses (ad) can become replication-competent when cotransduced with a CRAD to selectively supply E1 in trans in tumors. The resulting selective production of large numbers of the E1-deleted ad within the tumor mass will increase the transduction efficiency. We used a CRAD (Δ24RGD) that produces a mutant E1 without the ability to bind retinoblastoma but retaining viral replication competence in cancer cells with a defective pRb/p16. Ad-lacZ, adenovirus-luciferase (ad-luc), and adenovirus insulin-like growth factor-1R/dominant-negative (ad-IGF-1R/dn; 482, 950) are E1-deleted replication-defective adenoviruses. The combination of CRAD and ad-lacZ increased the transduction efficiency of lacZ to 100% from 15% observed with ad-lacZ alone. Transfer of media of CRAD and ad-lacZ cotransduced cells induced the transfer of lacZ (media transferable bystander effect). Combination of CRAD and ad-IGF-1R/dn increased the production of truncated IGF-1R or soluble IGF-1R > 10 times compared with transduction with ad-IGF-1R/dn alone. Combined intratumoral injection of CRAD and ad-luc increased the luciferase expression about 70 times compared with ad-luc alone without substantial systemic spread. Combined intratumoral injection of CRAD and ad-IGF-1R/482 induced stronger growth suppression of established lung cancer xenografts than single injections. The combination of CRAD and E1-deleted ad induced tumor-specific replication of CRAD and E1-deleted ad and increased the transduction rate and therapeutic efficacy of these viruses in model tumors.

Erratum: Production of vascular endothelial growth factor by human tumors inhibits the functional maturation of dendritic cells (Nature Medicine 2, 1096-1103 (1996))

Production of vascular endothelial growth factor by human tumors inhibits the functional maturation of dendritic cells Dmitry I. Gabrilovich, Hailei L. Chen, Khaled R. Girgis, H. Thomas Cunnigham, Geralyn M. Meny, Sorena Nadaf, Denise Kavanaugh & David P. Carbone Nature Medicine 2, 1096–1103 (1996) On page 1100 of the October issue, two neutralizing antibody labels on Fig. 5a were inadvertently switched. The correct placement appears below. Soluble HLA class I molecules induce apoptosis in alloreactive cytotoxic T lymphocytes Nicholaus Zavazava & Martin Krönke Nature Medicine 2, 1005–1010 (1996) On page 1006 of the September issue, the legend for Fig. 2a was incorrectly labeled. The correct labeling appears below.