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2-aminopurine enhances the oncolytic activity of an E1b-deleted adenovirus in hepatocellular carcinoma cells.

Sharon D, Schümann M, MacLeod S, McPherson R, Chaurasiya S, Shaw A, Hitt MM - PLoS ONE (2013)

Bottom Line: Furthermore, these mutations were also found to reduce the activity of the replicating viruses in certain cancer cells.We constructed an adenovirus with deletions of both the E1b and the VA-RNA genes and found that replication of this virus was selective for human hepatocellular carcinoma (HCC) cell lines when compared to normal cell lines.Furthermore, we show that 2-aminopurine (2'AP) treatment selectively enhanced virus replication and virus-mediated death of HCC cells. 2'AP did not compensate for the loss of VA-RNA activities, but rather the loss of an E1b-55K activity, such as the DNA damage response, suggesting that co-administration of 2'AP derivatives that block host DNA damage response, may increase the oncolytic activity of AdΔE1bΔVA without reducing its selectivity for HCC cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.

ABSTRACT
Adenoviruses with deletions of viral genes have been extensively studied as potential cancer therapeutics. Although a high degree of cancer selectivity has been demonstrated with these conditionally replicating adenoviruses, low levels of virus replication can be detected in normal cells. Furthermore, these mutations were also found to reduce the activity of the replicating viruses in certain cancer cells. Recent studies have shown that co-administration of chemotherapeutic drugs may increase the activity of these viruses without affecting their specificity. We constructed an adenovirus with deletions of both the E1b and the VA-RNA genes and found that replication of this virus was selective for human hepatocellular carcinoma (HCC) cell lines when compared to normal cell lines. Furthermore, we show that 2-aminopurine (2'AP) treatment selectively enhanced virus replication and virus-mediated death of HCC cells. 2'AP did not compensate for the loss of VA-RNA activities, but rather the loss of an E1b-55K activity, such as the DNA damage response, suggesting that co-administration of 2'AP derivatives that block host DNA damage response, may increase the oncolytic activity of AdΔE1bΔVA without reducing its selectivity for HCC cells.

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Related in: MedlinePlus

Treatment of HepG2 and MRC5 cells with 2.5 mM 2′AP inhibited AdΔE1b and AdΔE1bΔVA release.Cells were infected with either AdΔE1b or AdΔE1bΔVA at MOI of 1 GFU/cell for 1 hour prior to treatment with medium containing no drug or 2.5 mM 2′AP. Four days following infection, infected cells combined with the media (total virus) or the media alone (released virus) were harvested. Virus yields were determined by titration in Hep3B cells. Error bars correspond to +/−SD of quadruplicates (*p<0.05, ***p<0.001, one-way ANOVA).
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pone-0065222-g004: Treatment of HepG2 and MRC5 cells with 2.5 mM 2′AP inhibited AdΔE1b and AdΔE1bΔVA release.Cells were infected with either AdΔE1b or AdΔE1bΔVA at MOI of 1 GFU/cell for 1 hour prior to treatment with medium containing no drug or 2.5 mM 2′AP. Four days following infection, infected cells combined with the media (total virus) or the media alone (released virus) were harvested. Virus yields were determined by titration in Hep3B cells. Error bars correspond to +/−SD of quadruplicates (*p<0.05, ***p<0.001, one-way ANOVA).

Mentions: To examine the reported ability of 2′AP to reduce adenovirus release from infected cells [55], virus concentrations were measured from both the cells and media (total virus produced) as well as only the media (released virus) in HepG2 and MRC5 cells (Figure 4). In agreement with data shown in Figure 3B, we found little difference between the replication properties of AdΔE1b and AdΔE1bΔVA in HepG2 cells at 4 days post-infection, whereas there was a significant difference between the two viruses in MRC5. Furthermore, 2′AP treatment of HepG2 increased production of both viruses by approximately 4 orders of magnitude. Production of both AdΔE1b and AdΔE1bΔVA was also increased in MRC5 cells treated with 2′AP, however, this increase (10-fold) was much lower than in HepG2. Similar to a previous report [55], while most of the infectious virus particles were released when no drug was added, only approximately 10% of the virus was released from the HepG2 cells treated with 2′AP. Even though 90% of the virus was retained in cells treated with 2′AP, more virus was released following drug treatment than produced in untreated cells.


2-aminopurine enhances the oncolytic activity of an E1b-deleted adenovirus in hepatocellular carcinoma cells.

Sharon D, Schümann M, MacLeod S, McPherson R, Chaurasiya S, Shaw A, Hitt MM - PLoS ONE (2013)

Treatment of HepG2 and MRC5 cells with 2.5 mM 2′AP inhibited AdΔE1b and AdΔE1bΔVA release.Cells were infected with either AdΔE1b or AdΔE1bΔVA at MOI of 1 GFU/cell for 1 hour prior to treatment with medium containing no drug or 2.5 mM 2′AP. Four days following infection, infected cells combined with the media (total virus) or the media alone (released virus) were harvested. Virus yields were determined by titration in Hep3B cells. Error bars correspond to +/−SD of quadruplicates (*p<0.05, ***p<0.001, one-way ANOVA).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3672087&req=5

pone-0065222-g004: Treatment of HepG2 and MRC5 cells with 2.5 mM 2′AP inhibited AdΔE1b and AdΔE1bΔVA release.Cells were infected with either AdΔE1b or AdΔE1bΔVA at MOI of 1 GFU/cell for 1 hour prior to treatment with medium containing no drug or 2.5 mM 2′AP. Four days following infection, infected cells combined with the media (total virus) or the media alone (released virus) were harvested. Virus yields were determined by titration in Hep3B cells. Error bars correspond to +/−SD of quadruplicates (*p<0.05, ***p<0.001, one-way ANOVA).
Mentions: To examine the reported ability of 2′AP to reduce adenovirus release from infected cells [55], virus concentrations were measured from both the cells and media (total virus produced) as well as only the media (released virus) in HepG2 and MRC5 cells (Figure 4). In agreement with data shown in Figure 3B, we found little difference between the replication properties of AdΔE1b and AdΔE1bΔVA in HepG2 cells at 4 days post-infection, whereas there was a significant difference between the two viruses in MRC5. Furthermore, 2′AP treatment of HepG2 increased production of both viruses by approximately 4 orders of magnitude. Production of both AdΔE1b and AdΔE1bΔVA was also increased in MRC5 cells treated with 2′AP, however, this increase (10-fold) was much lower than in HepG2. Similar to a previous report [55], while most of the infectious virus particles were released when no drug was added, only approximately 10% of the virus was released from the HepG2 cells treated with 2′AP. Even though 90% of the virus was retained in cells treated with 2′AP, more virus was released following drug treatment than produced in untreated cells.

Bottom Line: Furthermore, these mutations were also found to reduce the activity of the replicating viruses in certain cancer cells.We constructed an adenovirus with deletions of both the E1b and the VA-RNA genes and found that replication of this virus was selective for human hepatocellular carcinoma (HCC) cell lines when compared to normal cell lines.Furthermore, we show that 2-aminopurine (2'AP) treatment selectively enhanced virus replication and virus-mediated death of HCC cells. 2'AP did not compensate for the loss of VA-RNA activities, but rather the loss of an E1b-55K activity, such as the DNA damage response, suggesting that co-administration of 2'AP derivatives that block host DNA damage response, may increase the oncolytic activity of AdΔE1bΔVA without reducing its selectivity for HCC cells.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.

ABSTRACT
Adenoviruses with deletions of viral genes have been extensively studied as potential cancer therapeutics. Although a high degree of cancer selectivity has been demonstrated with these conditionally replicating adenoviruses, low levels of virus replication can be detected in normal cells. Furthermore, these mutations were also found to reduce the activity of the replicating viruses in certain cancer cells. Recent studies have shown that co-administration of chemotherapeutic drugs may increase the activity of these viruses without affecting their specificity. We constructed an adenovirus with deletions of both the E1b and the VA-RNA genes and found that replication of this virus was selective for human hepatocellular carcinoma (HCC) cell lines when compared to normal cell lines. Furthermore, we show that 2-aminopurine (2'AP) treatment selectively enhanced virus replication and virus-mediated death of HCC cells. 2'AP did not compensate for the loss of VA-RNA activities, but rather the loss of an E1b-55K activity, such as the DNA damage response, suggesting that co-administration of 2'AP derivatives that block host DNA damage response, may increase the oncolytic activity of AdΔE1bΔVA without reducing its selectivity for HCC cells.

Show MeSH
Related in: MedlinePlus