Angiogenesis in non-small cell lung cancer. A new target for therapy

ED-B FIBRONECTIN IN NON–SMALL CELL LUNG CARCINOMA

Fibronectin (FN), a matrix glycoprotein, has been shown to undergo alternative splicing exclusively during organogenesis and tumorigenesis. One such splice variant, extradomain-B (ED-B) FN, is normally absent in normal adult tissues and is proposed to be a marker of tumoral angiogenesis. The present study was aimed at elucidating whether ED-B FN is expressed in non-small cell lung carcinomas and whether such aberrant expression correlates with tumoral angiogenesis. Frozen tissues from 28 non-small cell lung carcinomas (consisting of both squamous cell carcinomas and adenocarcinomas) along with paired normal tissue samples were collected from the tissue bank collection of the Department of Pathology, London Health Sciences Center, Canada. Frozen tissue specimens were subjected to RNA extraction and real time reverse transcriptase-polymerase chain reaction (RT-PCR) with respect to total and ED-B FN isoform expression. In addition, paraffin-embedded tissue sections from the same cases were collected for histological analysis using ED-B FN antibody. Tumor tissues were further stained with CD34 antibody and analyzed semiquantitatively for tumor microvessel density. The results demonstrate up-regulation of ED-B FN mRNA levels in lung tumor tissues as compared to paired normal tissues. Furthermore, ED-B FN expression was localized specifically to tumor cells and was found to correlate with tumor microvessel density. These findings provide evidence of possible involvement of ED-B FN in pulmonary tumoral angiogenesis. Furthermore, ED-B FN may potentially be used as a diagnostic marker and a target for antiangiogenic therapy.

The Plant Alkaloid Sanguinarine is a Potential Inhibitor of Follicular Angiogenesis

Sanguinarine (SA), a phytobiotic from Sanguinaria Canadensis, has been demonstrated to inhibit vessel growth. Current restrictions on the use of antibiotic growth promoters have motivated addition of this alkaloid as a naturally appetizing feed additive for farm animals. However, concern may araise since angiogenesis is a fundamental event in ovarian follicle growth. Therefore, the aim of this study was to evaluate the potential negative role of SA in follicular angiogenesis. For this purpose, we studied the effect of 300 nM SA on the production of vascular endothelial growth factor (VEGF) by swine granulosa cells from follicles >5 mm and on the activation of Akt, the main effector of the VEGF signalling pathway. In addition, the potential interference of SA in vessel development was tested in an in vitro angiogenesis bioassay. SA inhibited both VEGF production and VEGF-induced Akt activation in swine granulosa cells. Moreover, it was able to block vessel growth induced by VEGF. Taken together, our results suggest that SA could be detrimental to follicular angiogenesis, and therefore supplementation of feed with this alkaloid should be carefully considered.

Construction of recombinant eukaryotic expression vector for human endostatin and its expression in liver cancer cell line SMMC-7721

AIM: To construct the recombinant eukaryotic expression vector for human endostatin and express it in human liver cancer cell line SMMC-7721, and to observe its anti-angiogenesis activity in vitro.

METHODS: Human endostatin cDNA containing interleukin-2 (IL-2) secreting peptide was cloned into eukaryotic expression plasmid pcDNA3.0 to construct recombinant plasmid pCD-sEndo. The plasmid pCD-sEndo was transfected intoSMMC-7721 cells by cationic liposome. The positive cell clones were selected by G418 and named SMMC/sEndo. The expression of endostatin protein was analyzed by Western-blot. The activity of endostatin protein in the supernatant of SMMC/sEndo cells was explored by the angiogenesis experiment of chicken chorioallantoic membrane (CAM).

RESULTS: The eukaryotic expression vector pCD-sEndo was successfully constructed and was confirmed by enzyme digestion and sequence analysis. The endostatin protein was expressed in the supernatant of SMMC/sEndo cells, about 20 ku in size. No expression of endostatin protein was found in the control cells. There were fewer blood vessels in the CAM treated with endostatin protein, and the blood vessel density markedly decreased. Furthermore, the density decreased with the increase of endostatin protein.

CONCLUSION: The recombinant eukaryotic expression vector is correctly constructed. The human endostatin protein with the activity of anti-angiogenesis can be expressed and secreted in the supernatant of SMMC-7721 cells tranfected with pCD-sEndo.

Angiogenic activity of swine granulosa cells: effects of hypoxia and vascular endothelial growth factor Trap R1R2, a VEGF blocker

The possible role played by hypoxia and vascular endothelial growth factor (VEGF) in the regulation of follicular angiogenesis was studied in a three-dimensional fibrin gel model. Granulosa cells from follicles >5mm were subjected to normoxia (19% O2), partial (5% O2) or total (1% O2) hypoxia and their culture media were collected and used to stimulate porcine Aortic Endothelial Cells (AOC) included in the fibrin matrix. A suspension of AOC on microcarrier beads was pipetted in a fibrinogen solution (1 mg/ml PBS) before the addition of 1250 IU thrombine (250 microl) to catalize the gel formation. Granulosa cell conditioned media were tested in the presence or absence of VEGF Trap R1R2 (150 ng/ml), a potent VEGF inhibitor, that had its efficacy tested by adding VEGF (100 ng/ml) to AOC culture. Endothelial cell proliferation was measured at 48, 96, 144, 192 h by means of Scion Image Beta. A significant (p < 0.01) increase of AOC proliferation at each time of measurement was induced by culture media from granulosa cells subjected to partial (except at the end of the first 48 h) and total hypoxia compared to control and normoxia conditions, and by VEGF. VEGF Trap significantly (p < 0.01) inhibited the stimulatory effect of media conditioned by granulosa cells cultured in hypoxic conditions. These data suggest that hypoxia stimulates angiogenic activity of granulosa cells possibly by means of VEGF which could represent the main effector in promoting endothelial cell proliferation.