A novel function for dendritic cell: clearance of VEGF via VEGF receptor-1

Inhibition of the differentiation of monocyte-derived dendritic cells by human gingival fibroblasts

We investigated whether gingival fibroblasts (GFs) can modulate the differentiation and/or maturation of monocyte-derived dendritic cells (DCs) and analyzed soluble factors that may be involved in this immune modulation. Experiments were performed using human monocytes in co-culture with human GFs in Transwell® chambers or using monocyte cultures treated with conditioned media (CM) from GFs of four donors. The four CM and supernatants from cell culture were assayed by ELISA for cytokines involved in the differentiation of dendritic cells, such as IL-6, VEGF, TGFβ1, IL-13 and IL-10. The maturation of monocyte-derived DCs induced by LPS in presence of CM was also studied. Cell surface phenotype markers were analyzed by flow cytometry. In co-cultures, GFs inhibited the differentiation of monocyte-derived DCs and the strength of this blockade correlated with the GF/monocyte ratio. Conditioned media from GFs showed similar effects, suggesting the involvement of soluble factors produced by GFs. This inhibition was associated with a lower stimulatory activity in MLR of DCs generated with GFs or its CM. Neutralizing antibodies against IL-6 and VEGF significantly (P<0.05) inhibited the inhibitory effect of CM on the differentiation of monocytes-derived DCs and in a dose dependent manner. Our data suggest that IL-6 is the main factor responsible for the inhibition of DCs differentiation mediated by GFs but that VEGF is also involved and constitutes an additional mechanism.

Markers CD40, VEGF, AKT, PI3K, and S100 correlate with tumor stage in gastric cancer

BACKGROUND

To better understand gastric cancer occurrence and prognosis, we explored the expression of molecules in the CD40 pathway and their correlation with gastric cancer prognosis.

PATIENTS AND METHODS

We measured the expression of CD40, VEGF, AKT, PI3K, and S100 in gastric cancer tissues and adjacent normal tissues from 128 patients by immunohistochemistry.

RESULTS

The expression of CD40, VEGF, AKT, and PI3K were significantly higher in tumor tissue than in normal tissue, while S100 expression in dendritic cells (DC) was lower. Expression of CD40, VEGF, AKT, and PI3K significantly increased with T stage, while S100 expression decreased with T stage. Lymph node metastasis was associated with low or negative S100 expression. PI3K expression increased with clinical stage, while negative S100 expression was associated with higher clinical stages. Multivariate analysis did not indicate significant associations between any of these markers and recurrence or mortality.

CONCLUSION

The correlation between T stage of gastric cancer and the higher expression of CD40, VEGF, AKT, and PI3K, along with lower S100 expression in DC, may provide insights into future targets for more effective immunotherapy for cancer.

Nanoparticle mediated targeting of VEGFR and cancer stem cells for cancer therapy

Angiogenesis is a crucial process in tumor pathogenesis as it sustains malignant cells with nutrients and oxygen. It is well known that tumor cells secrete various growth factors, including VEGF, which triggers endothelial cells to form new capillaries. Prevention of expansion of new blood vessel networks results in reduced tumor size and metastasis. Production of VEGF is driven by hypoxia via transcriptional activation of the VEGF gene by HIF-1α.

Tumours are now understood to contain different types of cells, and it is the cancer stem cells that retain the ability to drive the tumour's growth. They are called cancer stem cells because, like stem cells present in normal tissues of the body, they can self-renew and differentiate. These cancer stem cells are responsible for the relapse of cancer as they are found to be resistant to conventional modes of cancer therapy like chemotherapy and radiation.

In this review, a novel mode of treatment of cancer is proposed, which utilizes the twin nanoparticle to target endothelial cells in the niche of cancer stem cell. The nanoparticle discussed in this review, is a twin nanoparticle of iron coated with gold, which targets VEGF positive cell in the vicinity of cancer stem cell. In the twin nanoparticle, one particle will recognize cancer stem cell, and another conjugated nanoparticle will recognize VEGF positive cells, thereby inhibiting endothelial cells in the proximity of cancer stem cell. This novel strategy will inhibit angiogenesis near cancer stem cell hence new tumour cannot grow and old tumour will be unable to metastasize.

Antagonism of VEGF by genetically engineered dendritic cells is essential to induce antitumor immunity against malignant ascites

Malignant ascitis (MA) is a highly intractable and immunotherapy-resistant state of advanced gastrointestinal and ovarian cancers. Using a murine model of MA with CT26 colon cancer cells, we here determined that the imbalance between the VEGF-A/vascular permeability factor and its decoy receptor, soluble fms-like tryrosine kinase receptor-1 (sFLT-1), was a major cause of MA resistance to dendritic cell (DC)-based immunotherapy. We found that the ratio of VEGF-A/sFLT-1 was increased not only in murine but also in human MA, and F-gene-deleted recombinant Sendai virus (rSeV/dF)-mediated secretion of human sFLT-1 by DCs augmented not only the activity of DCs themselves, but also dramatically improved the survival of tumor-bearing animals associated with enhanced CTL activity and its infiltration to peritoneal tumors. These findings were not seen in immunodeficient mice, indicating that a VEGF-A/sFLT-1 imbalance is critical for determining the antitumor immune response by DC-vaccination therapy against MA.