Evaluation of tumor-specific promoter activities in melanoma

Abstract

Gene therapy is a novel therapy for melanoma. To date, however, there is still no powerful tumor specific promoter (TSP) to restrict the transgene expression in melanoma cells. In order to define a useful TSP for targeting in the context of melanoma gene therapy, four promoters, the cyclooxygenase-2 (Cox-2), a-chemokine SDF-1 receptor (CXCR4), epithelial glycoprotein 2 (EGP-2), and survivin, were tested in both established melanoma cell lines and primary melanoma cells. We employed recombinant adenoviral vectors (reAds) each with a candidate TSP (the Cox-2, CXCR4, EGP-2, or survivin), a reporter luciferase gene, and a poly-A signal, all of which were inserted into the E1-deleted region. A reAdGL3Bcytomegalovirus (CMV), containing the CMV promoter and luciferase gene, was used as a positive control to normalize the luciferase activity. Luciferase activity was measured in multiple tumor cell lines and two primary melanoma cell cultures after infection with reAds. Human epithelial melanocytes, HEM, were used as normal control. In contrast to three other promoters, the survivin promoter exhibited the highest activities within both melanoma cell lines and primary melanoma cells, but not in HEMs. Additionally, the survivin promoter exhibited very low activities in major mouse organs including the liver, in vivo. EGP-2 is not active in melanoma; messenger RNA expressions were correlated to promoter activities both in melanoma cell lines and primary cell cultures. Thus, these data suggest that the survivin promoter achieved a 'tumor-on/ liver-off' profile, and thus represents a potentially useful tumor-specific promoter with applications for transcriptional targeting of Ad vector-based cancer gene therapy or oncolysis to melanoma. Gene Therapy (2005) 12, 330-338.

Targeted therapy by disablingcrossroadsignaling networks: the survivin paradigm

“…A second approach involved the use of the survivin gene to express a ''payload'' cytotoxic gene in tumor cells. This ''suicidal'' strategy (41) relies on the fact that the survivin gene has virtually no transcriptional expression in normal tissues, including liver (42), as opposed to a 200-fold increased activity in tumor cells in vivo (43). When coupled to a proapoptotic protein, administration of the suicidal construct as a DNA-liposome formulation resulted in complete tumor eradication in xenograft models (43), thus offering good prospects for further clinical development.…”

Suppression of hepatoma tumor growth by systemic administration of the phytotoxin gelonin driven by the survivin promoter

“…Numerous researches have validated the specificity and utility of survivin promoter for tumor targeting therapy [26]. Survivin is over-expressed in common cancers, but not in normal adult tissues [27][28][29]. A series of studies confirmed that survivin mRNA was expressed in 12 human hepatoma cell lines, and survivin protein was highly positive in 70% of liver cancers.…”

Gene therapy progress and prospects: the skin – easily accessible, but still far away

“…7 Aside from cellular targeting, transcriptional targeting has recently also been assessed in primary melanoma cells, the most important skin tumor. 8 In these experiments, the survivin promotor exhibited the highest activity in melanoma cells, while normal tissues such as liver, lung and spleen were relatively spared. Combinations of cellular targeting using RGD fiber-mutant adenovirus vectors that contain an alpha-v integrin tropism with the melanoma-specific tyrosinase promotor or human telomerase reverse transcriptase (TERT) promotor have shown increased gene expression in tumor cells with a relative quiescence in normal cells.…”