Overexpression of both VEGF-A and VEGF-C in gastric cancer correlates with prognosis, and silencing of both is effective to inhibit cancer growth

BACKGROUND

Vascular endothelial growth factor (VEGF)-A and VEGF-C are two important molecules involving in tumor development and metastasis via angiogenesis and lymphangiogenesis. However, the combined effect of VEGF-A and VEGF-C on the growth of gastric cancer (GC) is not clear.

METHODS

The correlations of VEGF-A and VEGF-C expressions with clinicopathologic parameters and prognosis were evaluated in patients with GC. Furthermore, lentivirus-mediated RNA interfering (RNAi) targeting VEGF-A and/or VEGF-C was employed to silence their expressions in SGC7901 GC cell line. Cell proliferation and apoptosis were measured in vitro. Suppressive effect lentivirus-mediated VEGF-A and/or VEGF-C silencing on GC growth was evaluated in GC bearing mice.

RESULTS

The patients with high expression of both VEGF-A and VEGF-C (A+C+) had larger tumor size, higher peritumoral lymphatic vessel density(P-LVD), microvessel density(MVD), lymphatic vessel invasion (LVI), lymph node(LN) metastasis, and worse prognosis than those with low expression of both VEGF-A and VEGF-C (P<0.05). Lentivirus-mediated RNAi significantly reduced the mRNA and protein expression of VEGF-A and VEGF-C in the SGC7901 cells. The Lenti-miRNA-VEGF-A+VEGF-C significantly inhibited the cell proliferation and tumor growth, compared with Lenti-miRNA-VEGF-A or Lenti-miRNA-VEGF-C (P<0.05). In addition, Lenti-miRNA- VEGF-A+VEGF-C markedly lowered the tumor size in vivo in comparison with Lenti-miRNA-VEGF-A or Lenti-miRNA-VEGF-C (P<0.05).

CONCLUSION

Expressions of both VEGF-A and VEGF-C predict worse prognosis of GC patients. Combined silencing of VEGF-A and VEGF-C markedly suppresses cancer growth than silencing of VEGF-A or VEGF-C. Thus, to inhibit the expressions of VEGF-A and VEGF-C may become a novel strategy for the treatment of GC.

Role of growth factors in improved skin flap viability caused by phosphodiesterase-5 inhibitor

Flap necrosis is one of the major complications of reconstructive surgery and sildenafil citrate has been shown to decrease flap necrosis in preclinical animal models. However, the mechanisms underlying sildenafil's therapeutic efficacy are not known. As with other phosphodiesterase 5 selective inhibitors, sildenafil causes vasodilation and enhanced blood flow. In addition, sildenafil can also alter gene expression. This study is designed to test the hypothesis that increased expression of angiogenic growth factors may be responsible for therapeutic efficacy of sildenafil. A modified McFarlane flap measuring 3 x 10 cm was created on the dorsal skin of male Sprague-Dawley rats. For growth factor expression experiment, rats were administered either vehicle or sildenafil 10 mg/Kg intraperitoneal (IP). Ribonucleic acid (RNA) extracted from skin flap was analyzed to assess the messenger ribonucleic acid (mRNA) levels of different angiogenic growth factors. For skin flap viability experiment, fibrin film impregnated with vehicle, fibroblast growth factor (FGF) (5.0 microg) or vascular endothelial growth factor (VEGF) (2.0 microg) was applied to the wound. The skin flap was then returned to its native position and stapled in place. Total affected area (area of necrosis and blood flow stasis) of each rat on postoperative day 14 was analyzed with orthogonal polarization spectral imaging. Daily systemic treatment with sildenafil significantly (P < 0.05) increased the expression of FGF1 and FGF Receptor 3 on postoperative day 3 by 5.08- and 4.78-fold, respectively. In addition, sildenafil increased the expression of VEGF-A, VEGF-B, and VEGF-C by 2.66-, 2.02-, and 2.00-fold, respectively. Subcutaneous treatment with FGF but not VEGF-A tended to decrease total affected area in rats. These data demonstrate that sildenafil altered the expression of FGF and VEGF. Altered expression of growth factors may be, at least partly, responsible for the beneficial effects of sildenafil citrate on skin viability.

Inhibition of the mammalian target of rapamycin impedes lymphangiogenesis

Lymphatic complications are common side effects of mammalian target of rapamycin (mTOR) inhibitor-based immunosuppression in kidney transplantation. Therefore, we investigated whether the mTOR inhibitor rapamycin, besides its known antihemangiogenic effect, also impedes regenerative lymphangiogenesis. In a murine skin flap model, rapamycin impaired recovery of lymphatic flow across surgical incisions resulting in prolonged wound edema in these animals. Importantly, the antilymphangiogenic effect of rapamycin was not related to a general inhibition of wound healing as demonstrated an in vivo Matrigeltrade mark lymphangiogenesis assay and a model of lymphangioma. Rapamycin concentrations as low as 1 ng/ml potently inhibited vascular endothelial growth factor (VEGF)-C driven proliferation and migration, respectively, of isolated human lymphatic endothelial cells (LECs) in vitro. Mechanistically, mTOR inhibition impairs downstream signaling of VEGF-A as well as VEGF-C via mTOR to the p70S6 kinase in LECs. In conclusion, we provide extensive experimental evidence for an antilymphangiogenic activity of mTOR inhibition suggesting that the early use of mTOR inhibitor following tissue injury should be avoided. Conversely, the antilymphangiogenic properties of rapamycin and its derivates may provide therapeutic value for the prevention and treatment of malignancies, respectively.

Pulmonary Vascular Endothelial Growth Factor-C in Development and Lung Injury in Preterm Infants

RATIONALE

In mice, vascular endothelial growth factor-C (VEGF-C) plays an important role in development of the lymphatic system and in pathogenesis of pulmonary inflammation. Its role in development of the lymphatic system in human lung and in lung injury in newborns remains unclear.

OBJECTIVES

We studied the role of VEGF-C in developing human lung, and in acute and chronic lung injury in preterm infants.

METHODS

Included in the immunohistochemistry study were 10 fetuses, 15 control neonates without primary lung disease, 15 preterm infants with respiratory distress syndrome, and 8 infants with bronchopulmonary dysplasia. Tracheal aspirate fluid samples of intubated very-low-birth-weight infants during Postnatal Weeks 1-5 were analyzed with ELISA.

RESULTS

Bronchiolar staining for VEGF-C was observed in all 48 samples. Alveolar epithelial staining was seen in most fetuses (8/10). In addition, staining was observed in alveolar macrophages in bronchopulmonary dysplasia (4/8), and late respiratory distress syndrome (2/7). VEGF receptor-3 (VEGFR-3) staining was observed in lymphatic endothelium adjacent to vascular endothelium. VEGF-C was expressed consistently in tracheal aspirate fluid, being highest during the first 2 postnatal days. Antenatal administration of glucocorticoids was associated with higher VEGF-C in tracheal aspirate fluid.

CONCLUSIONS

The pattern of pulmonary VEGF-C and VEGFR-3 protein expression and consistent VEGF-C protein appearance in tracheal aspirate fluid in human preterm infants indicate a role for VEGF-C in the physiologic development of the lymphatic system of the lung.