Low-dose endostatin normalizes the structure and function of tumor vasculature and improves the delivery and anti-tumor efficacy of cytotoxic drugs in a lung cancer xenograft murine model.

INTRODUCTION: To some extent endostatin normalizes tumor vasculature. However, the optimum time window and optimum drug dose for tumor vascular normalization need to be explored. Here we investigate the effect of low-dose endostatin on the structure and function of tumor vasculature and the delivery and anti-tumor efficacy of cytotoxic drugs. METHODS: A lung cancer xenograft murine model was treated with low-dose endostatin for 10 days. The structure and function of the tumor vasculature were evaluated using various techniques. Paclitaxel was added in different schedules. RESULTS: Endostatin caused a significant reduction in microvessel density. Tumor vascular walls after endostatin treatment were better structured. Tumor blood perfusion was increased on day six after endostatin administration. On days three, six, and 10, Evans blue extravasation into the parenchyma of tumors was decreased. On days three and six, endostatin-treated mice had greater paclitaxel delivery. The time window of vascular normalization was approximately three to six days. On days one to three, and days four to six, combined therapy with paclitaxel significantly inhibited tumor growth. CONCLUSIONS: Low-dose endostatin aids normalization of tumor vasculature. This resulted in improved delivery of cytotoxic drugs to the tumor, which closely correlates with synergistic efficacy when combined with paclitaxel during the normalization window.

Effect of endostatin on preventing postoperative progression of distant metastasis in a murine lung cancer model.

AIMS AND BACKGROUND: The relapse and metastasis of cancer remain a predominant cause of death after surgical removal of the primary tumor. There is a positive linkage between the postoperative upregulation of systemic angiogenic activity and distant tumor metastasis. In the present study, we established a spontaneous metastasis model and investigated whether antiangiogenic therapy using endostatin could prevent the progression of distant metastasis after removal of the primary tumor. METHODS: Female C57BL/6 mice were implanted subcutaneously with 1 × 106 Lewis lung cancer cells. Twenty days after implantation of the cancer cells, the primary tumor was removed and the mice were randomly divided into three groups. The NS group received normal saline, the L-ES group received 3 mg/kg endostatin, and the H-ES group received 20 mg/kg endostatin intravenously daily for 10 days. The effect of endostatin on lung metastases and the survival time of the mice were observed. Flow cytometry and immunohistochemistry were carried out to assess the angiogenic activity. The serum endostatin levels in peripheral blood were measured using an enzyme-linked immunosorbent assay. RESULTS: The mean number of metastatic pulmonary nodules and the mean net lung weight in the NS, L-ES and H-ES groups was 10.2, 2.8 and 4.0, and 0.55 g, 0.31 g and 0.36 g, respectively. The difference between the NS group and the endostatin-treated groups was statistically significant (P <0.05). The endostatin-treated mice showed prolonged overall survival (P <0.05). Compared with the NS group, the endostatin-treated groups had lower levels of circulating endothelial cells in peripheral blood and showed a decrease in microvessel density in the metastatic tumors, with a more marked reduction in the L-ES group (P <0.05). The systemic presence of endostatin was gradually increased with the continued administration of endostatin to the mice. CONCLUSIONS: Antiangiogenic therapy with endostatin is effective in inhibiting the postoperative progression of distant metastasis.

[Detection of anisakid nematodes by an SYBR green I real-time PCR].

OBJECTIVE: To establish an SYBR Green I real-time quantitative PCR method for the detection of anisakid nematodes with zoonotic potential from Taiwan Strait. METHODS: Anisakid larvae of six species (Anisakis simplex, A. physeteris, Raphidascaris trichiura, Contracaecum aduncum, C. muraenesoxi, and Contracaecum sp., a predominant species in fishes in the strait) were obtained from the guts of marine fishes and identified chiefly based on the morphological features. The ITS-2 rDNA sequences from the larvae were amplified by PCR using universal primers, then cloned and bidirectionally sequenced. According to these sequences, six specific forward primers were designed and synthesized. Specificity was determined by a series of conventional PCR respectively, the ITS-2 sequences amplified above were cloned into T vector which was subsequently transformed into E. coli DH5alpha. Following extraction and identification, the positive recombinant plasmid was used as quantitative template to generate standard curve and melt curve. Sensitivity and reproducibility were determined. RESULTS: All the 6 standard curves established by the recombinant plasmids showed adequate linear relationship between threshold cycle (Ct) and template concentration. Melt curves were specific and all the 6 correlation coefficients were above 0.998. In the reproducibility test, the coefficients of variation (cv) of Ct values for detection of the 6 nematodes ranged between 0.18% and 2.80%, and the cv of the inter-assay ranged between 0.55% and 1.94%. The sensitivity of the real-time PCR was 1 x 10(2) copies/microl, about 100 times higher than the conventional PCR assays. The real-time quantitative PCR detection needed only 3.5 hours from the sample treatment to result report. CONCLUSION: An SYBR Green I fluorescent quantitative PCR has been developed for detecting anisakid nematodes with adequate sensitivity and specificity.