INVESTIGADORES
VIALE Diego Luis
congresos y reuniones científicas
Título:
Targeting malingnant and tumor associated-stromal cells as a novel strategy for cancer gene therapy
Autor/es:
LOPEZ, MV; VIALE, DL; CAFFERATA EG; WU, H; RIVERA, AA; GOULD, D; CHERNAJOVSKY, Y; CURIEL, DT; PODHAJCER, OL
Lugar:
Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
Reunión:
Simposio; In vivo barriers to gene delivery; 2007
Institución organizadora:
Cold Spring Harbor Laboratory
Resumen:
SPARC is a
matricellular protein that is overexpressed in malignant and tumor
associated-stromal cells in human melanomas and other cancers as well. By using
luciferase expression as a reporter gene, we performed a detailed analysis of
the activity and specificity of different fragments of the SPARC promoter. A
promoter sequence extending from 513 bp to +35 bp named F512 showed the best
ratio of activity vs. specificity in human melanoma cells compared to
non-melanoma malignant and normal cells. We constructed a conditional
replicative adenoviral vector (CRAd) in which the E1A gene was driven by F512
(Ad-F512) and a second virus Ad(I)-F512-TK in which an insulator sequence was
placed between the ITR and F512 and also contained the thymidine kinase gene.
Both CRAds were cytotoxic on a panel of melanoma cells but were unable to
replicate in normal cells from different origins including melanocytes,
keratinocytes, mammary and colon cells. Ad-F512 treatment of mice carrying
established melanomas inhibited tumor growth in 7 out of 9 mice compared to
none in the control group treated with Ad-Bgal. Ad(I)-F512-TK combined with GCV
significantly enhanced the efficacy of the CRAd both in melanoma and in HMEC-1
human transformed microendothelial cells expressing SPARC. Therefore, we sought
to establish whether treatment with Ad(I)-F512-TK + GCV can be effective on
established tumors composed of malignant and endothelial cells in which only
the latter expressed SPARC. Indeed, Ad(I)-F512-TK +GCV treatment of mixed
tumors made of MiaPaca human pancreatic cancer cells and HMEC-1 inhibited tumor
growth in 5 out of 6 mice. Since adenovirus type 5 efficacies for therapeutic
gene transfer to human melanoma cells can be limited by the low expression of
the coxsackie and adenovirus receptor, CAR, several strategies have been
proposed to ablate Ad5 native tropism. Therefore, we modified the tropism of
Ad-F512 and Ad(I)-F512-TK by 5/3, RGD or pK7 fiber modifications. These new CRAds
were tested in a panel of cancer, stromal and normal cells. We found that
capsid modified CRAds possess enhanced ability for transduction of melanoma,
transformed fibroblasts and endothelial cells. Normal cells are being tested.
The whole data indicate that oncolytic adenoviruses whose replication is driven
by a specific SPARC promoter fragment might be considered as a potential
therapeutic tool for different cancer types.