Antiangiogenic cancer gene therapy by adeno-associated virus 2-mediated stable expression of the soluble FMS-like tyrosine kinase-1 receptor
Authors: Sreelatha Meleth
Tatyana Isayeva
Cecil R Stockardt
David T Curiel
Gandham Mahendra
Raj Singh
Selvarangan Ponnazhagan
Gene P Siegal
Vidya Alapati
Sanjay Kumar
William E Grizzle
Parameshwar J Mahasreshti
Journal: Cancer Gene Therapy (2005)
Discipline: CLINICAL MEDICINE
Keywords: Antiangiogenic gene transfer; protein-based therapies; pharmacotherapies; solid tumor growth; invasion
Affiliations: Department of Pathology, The University of Alabama at Birmingham, Birmingham, AL 35294, USA.

Abstract:  Antiangiogenic gene transfer has the potential to be more efficacious than protein-based therapies or pharmacotherapies for the control of solid tumor growth, invasion and metastasis. For a sustained antiangiogenic effect, a vector capable of long-term expression without vector-associated immunity or toxicity is advantageous. The present study evaluated the potential of a recombinant adeno-associated virus-2 (rAAV) encoding the human soluble FMS-like tyrosine kinase receptor 1 (sFlt-1), which functions by both sequestering vascular endothelial growth factor (VEGF) and forming inactive heterodimers with other membrane-spanning VEGF receptors, in vitro and in vivo. Results indicated significant growth inhibitory activity of the transgenic factor in a human umbilical vein endothelial cell proliferation assay in vitro and protection against the growth of an angiogenesis-dependent human ovarian cancer cell line, SKOV3.ip1, xenograft in vivo with increased disease-free survival. Stable expression of the secretory factor and transgene persistence were confirmed by immunohistochemistry and in situ hybridization analyses, respectively. Increased therapeutic effects on both the growth index of the implanted tumor cells and tumor-free survival also correlated with an increasing dose of the vector used. These studies indicate that rAAV-mediated sFlt-1 gene therapy may be a feasible approach for inhibiting tumor angiogenesis, particularly as an adjuvant/therapy. 

Retracted: No

PubPeer comments:
 Figure 2 appeared to be overexposed so I adjusted the exposure -25% which revealed some additional minor features and an unusual background, including a sharp horizontal contrast ~40 kDa. Could the authors comment? Top: Figure 2, exposure adjusted; Bottom: original Figure 2 ***  ***  , 
 Lane 1 is a positive control (purified protein) that lights up very strongly. What is pointed out as ~40 kDa band in the above question is a non-specific band that appears in proteins form both control (mock-transduction) and rAAV-sFlt-1 vector lanes. We alluded to this in the Figure legend (A band of approximately 50 kDa, from nonspecific hybridization is seen in both mock-transduced and rAAV-sFlt-1-transduced lanes). , 
 #2 Thank you sincerely for your reply and apologies for not making my question more clear. I was curious as to why the background shading that was revealed when the exposure was adjusted appears as it does. These could be image artifacts; image artifacts that coincidentally appear in lane 1 (red) to be a horizontal line across the gel at the bottom (red), and at the right side (yellow). Otherwise it looks like the gel could have been cropped at ~40 kDa and a brush tool used to edit the image around the control. ***  ,