Adenovirus-mediated TA-p73β gene transfer increases chemosensitivity of human malignant melanomas

Malignant melanoma is the most aggressive form of skin cancer and has proven to be highly resistant to conventional chemotherapy. Intriguingly, the p53 tumor suppressor, a main mediator of chemoresistance in other tumor types, is rarely mutated in melanoma. However, we have previously shown that anti-apoptotic isoforms of p73 (ΔTA-p73), another member of the p53 family, are overexpressed in metastatic melanomas. ΔTA-p73 can oppose the pro-apoptotic functions of p53 and full length p73, and thus it could contribute to melanoma chemoresistance. In this study, we use an efficient adenoviral-based gene transfer approach to introduce a transcriptionally active form of p73 (TA-p73β) in melanoma cells, with the objective of overcoming drug resistance. Interestingly, TA-p73β significantly sensitized 5 out of 7 aggressive melanoma cell lines to the standard therapeutic agents adriamycin and cisplatin. More importantly, TA-p73β displayed a synergistic effect in vivo allowing adriamycin or cisplatin to block melanoma cell growth in mouse xenograft models ( p < 0.05). In summary, our data show that Ad-mediated TA-p73β gene expression can markedly sensitize a subset of melanoma cell lines to adriamycin and cisplatin in vitro and in vivo , suggesting a new chemosensitization strategy for malignant melanomas.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44369/1/10495_2006_Article_3407.pd

Adenoviral p53 gene transfer inhibits human Tenon’s capsule fibroblast proliferation

Background/aim: Although antiproliferative drugs have been used successfully to prevent scarring after filtration surgery in patients with glaucoma, complications associated with their use (such as hypotony or endophthalmitis) energise the search for an alternative treatment. Single application of β radiation leads to long term growth arrest and expression of p53 in human Tenon’s capsule fibroblasts (hTf). The authors assume that the activation of p53 is one of the cellular triggers. Their aim was to analyse the effect of p53 overexpression on hTf and to determine which pathways are involved. Methods: A recombinant adenoviral vector (rAd.p53) containing transgenes encoding for human p53 and green fluorescent protein (GFP) was used to induce overexpression of p53 in hTF and a control vector (rAd.GFP). Transgene expression was detected by western blot (p53 and p21(WAF-1/Cip1)). Cell proliferation and viability were investigated using cell counts, 5′-bromodeoxyuridine incorporation (BrdU assay) and tetrazolium reduction (MTT assay). Results: Infection of hTf with rAd.p53 resulted in significant inhibition of cell proliferation, DNA synthesis, and metabolic activity in vitro. Western blot showed increased levels of p53 and p21(WAF-1/Cip1) in rAd.p53 infected cells, but not in rAd.GFP and uninfected cells. Apoptosis was excluded with flow cytometry. Conclusions: Adenoviral p53 gene transfer leads to significant growth inhibition in hTf. P53 induces p21(WAF-1/Cip1) expression and does not cause apoptosis in hTf in vitro. p53 as an antiproliferative drug has the potential to replace mitomycin C and 5-fluorouracil in glaucoma surgery