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Creation of a Merkel cell polyomavirus small T antigen-expressing murine tumor model and a DNA vaccine targeting small T antigen.

Gomez B, He L, Tsai YC, Wu TC, Viscidi RP, Hung CF - Cell Biosci (2013)

Bottom Line: MCPyV LT antigen expression was found to be a requirement for MCC tumor maintenance and ST protein also likely contributes to the carcinogenesis of MCC.The LT-targeting DNA vaccine generated prolonged survival, decreased tumor size and increased LT-specific CD8+ T cells in tumor-bearing mice.In ST-expressing tumor-bearing mice, this vaccine, pcDNA3-MCC/ST, generated a significant number of ST antigenic peptide-specific CD8+ T cells and experienced markedly enhanced survival compared to mice vaccinated with empty vector.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departments of Pathology, Johns Hopkins Medical Institutions, Baltimore, MD, USA. chung2@jhmi.edu.

ABSTRACT

Background: Merkel cell polyomavirus (MCPyV) is a DNA virus expressing transcripts similar to the large T (LT) and small T (ST) transcripts of SV40, which has been implicated in the pathogenesis of Merkel cell carcinoma (MCC), a rare and highly aggressive neuroendocrine skin cancer. MCPyV LT antigen expression was found to be a requirement for MCC tumor maintenance and ST protein also likely contributes to the carcinogenesis of MCC. Previously, we have identified the probable immunodominant epitope of MCPyV LT and developed a DNA vaccine encoding this epitope linked to calreticulin. The LT-targeting DNA vaccine generated prolonged survival, decreased tumor size and increased LT-specific CD8+ T cells in tumor-bearing mice.

Results: In this study, we developed a MCPyV ST-expressing tumor cell line from B16 mouse melanoma cells. We then utilized this ST-expressing tumor cell line to test the efficacy of a DNA vaccine encoding ST. In ST-expressing tumor-bearing mice, this vaccine, pcDNA3-MCC/ST, generated a significant number of ST antigenic peptide-specific CD8+ T cells and experienced markedly enhanced survival compared to mice vaccinated with empty vector.

Conclusions: The formation of an effective vaccine against MCPyV has the potential to advance the field of MCC therapy and may contribute to the control of this severe malignancy through immunotherapy. Both of the innovative technologies presented here provide opportunities to develop and test MCPyV-targeted therapies for the control of Merkel cell carcinoma.

No MeSH data available.


Related in: MedlinePlus

In vivo tumor protection experiments. (A) An outline of the vaccination schedule using either pcDNA3-MCC/ST DNA vaccine or empty vector control vaccine pcDNA3. C57BL/6 mice (5 per group) were immunized with either pcDNA3-MCC/ST or pcDNA3DNA vaccine intradermally with DNA-coated particles using a helium-driven gene gun 3 times at 4-day intervals. Ten days after the last vaccination, vaccinated mice were challenged subcutaneously in the right flank with B16/ST tumor (1×105 cells/mouse). (B) Survival plot depicting the percentage of vaccinated mice surviving following vaccination with either pcDNA3-MCC/ST DNA vaccine or empty vector control pcDNA3. (C) Plot depicting tumor volume over time. Tumors were measured with digital calipers and tumor volumes calculated.
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Figure 3: In vivo tumor protection experiments. (A) An outline of the vaccination schedule using either pcDNA3-MCC/ST DNA vaccine or empty vector control vaccine pcDNA3. C57BL/6 mice (5 per group) were immunized with either pcDNA3-MCC/ST or pcDNA3DNA vaccine intradermally with DNA-coated particles using a helium-driven gene gun 3 times at 4-day intervals. Ten days after the last vaccination, vaccinated mice were challenged subcutaneously in the right flank with B16/ST tumor (1×105 cells/mouse). (B) Survival plot depicting the percentage of vaccinated mice surviving following vaccination with either pcDNA3-MCC/ST DNA vaccine or empty vector control pcDNA3. (C) Plot depicting tumor volume over time. Tumors were measured with digital calipers and tumor volumes calculated.

Mentions: Using the vaccination regimen depicted in Figure 3A, we performed in vivo tumor protection experiments to analyze the protective antitumor effects of pcDNA3-MCC/ST DNA vaccine. C57BL/6 mice were vaccinated with pcDNA3-MCC/ST DNA or pcDNA3 empty vector as a control. Vaccinated mice were challenged with B16/ST tumor cells subcutaneously one week after the last vaccination. As shown in Figure 3B, mice vaccinated with pcDNA3-MCC/ST had significantly longer survival compared to mice vaccinated with pcDNA3. Furthermore, the tumor volume of mice vaccinated with pcDNA3-MCC/ST was significantly lower than that of mice vaccinated with pcDNA3 (Figure 3C). Thus, our data show that pcDNA3-MCC/ST DNA vaccine generated strong protective antitumor effects in vaccinated mice (pcDNA3-MCC/ST vs. pcDNA3 p=0.002).


Creation of a Merkel cell polyomavirus small T antigen-expressing murine tumor model and a DNA vaccine targeting small T antigen.

Gomez B, He L, Tsai YC, Wu TC, Viscidi RP, Hung CF - Cell Biosci (2013)

In vivo tumor protection experiments. (A) An outline of the vaccination schedule using either pcDNA3-MCC/ST DNA vaccine or empty vector control vaccine pcDNA3. C57BL/6 mice (5 per group) were immunized with either pcDNA3-MCC/ST or pcDNA3DNA vaccine intradermally with DNA-coated particles using a helium-driven gene gun 3 times at 4-day intervals. Ten days after the last vaccination, vaccinated mice were challenged subcutaneously in the right flank with B16/ST tumor (1×105 cells/mouse). (B) Survival plot depicting the percentage of vaccinated mice surviving following vaccination with either pcDNA3-MCC/ST DNA vaccine or empty vector control pcDNA3. (C) Plot depicting tumor volume over time. Tumors were measured with digital calipers and tumor volumes calculated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 3: In vivo tumor protection experiments. (A) An outline of the vaccination schedule using either pcDNA3-MCC/ST DNA vaccine or empty vector control vaccine pcDNA3. C57BL/6 mice (5 per group) were immunized with either pcDNA3-MCC/ST or pcDNA3DNA vaccine intradermally with DNA-coated particles using a helium-driven gene gun 3 times at 4-day intervals. Ten days after the last vaccination, vaccinated mice were challenged subcutaneously in the right flank with B16/ST tumor (1×105 cells/mouse). (B) Survival plot depicting the percentage of vaccinated mice surviving following vaccination with either pcDNA3-MCC/ST DNA vaccine or empty vector control pcDNA3. (C) Plot depicting tumor volume over time. Tumors were measured with digital calipers and tumor volumes calculated.
Mentions: Using the vaccination regimen depicted in Figure 3A, we performed in vivo tumor protection experiments to analyze the protective antitumor effects of pcDNA3-MCC/ST DNA vaccine. C57BL/6 mice were vaccinated with pcDNA3-MCC/ST DNA or pcDNA3 empty vector as a control. Vaccinated mice were challenged with B16/ST tumor cells subcutaneously one week after the last vaccination. As shown in Figure 3B, mice vaccinated with pcDNA3-MCC/ST had significantly longer survival compared to mice vaccinated with pcDNA3. Furthermore, the tumor volume of mice vaccinated with pcDNA3-MCC/ST was significantly lower than that of mice vaccinated with pcDNA3 (Figure 3C). Thus, our data show that pcDNA3-MCC/ST DNA vaccine generated strong protective antitumor effects in vaccinated mice (pcDNA3-MCC/ST vs. pcDNA3 p=0.002).

Bottom Line: MCPyV LT antigen expression was found to be a requirement for MCC tumor maintenance and ST protein also likely contributes to the carcinogenesis of MCC.The LT-targeting DNA vaccine generated prolonged survival, decreased tumor size and increased LT-specific CD8+ T cells in tumor-bearing mice.In ST-expressing tumor-bearing mice, this vaccine, pcDNA3-MCC/ST, generated a significant number of ST antigenic peptide-specific CD8+ T cells and experienced markedly enhanced survival compared to mice vaccinated with empty vector.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departments of Pathology, Johns Hopkins Medical Institutions, Baltimore, MD, USA. chung2@jhmi.edu.

ABSTRACT

Background: Merkel cell polyomavirus (MCPyV) is a DNA virus expressing transcripts similar to the large T (LT) and small T (ST) transcripts of SV40, which has been implicated in the pathogenesis of Merkel cell carcinoma (MCC), a rare and highly aggressive neuroendocrine skin cancer. MCPyV LT antigen expression was found to be a requirement for MCC tumor maintenance and ST protein also likely contributes to the carcinogenesis of MCC. Previously, we have identified the probable immunodominant epitope of MCPyV LT and developed a DNA vaccine encoding this epitope linked to calreticulin. The LT-targeting DNA vaccine generated prolonged survival, decreased tumor size and increased LT-specific CD8+ T cells in tumor-bearing mice.

Results: In this study, we developed a MCPyV ST-expressing tumor cell line from B16 mouse melanoma cells. We then utilized this ST-expressing tumor cell line to test the efficacy of a DNA vaccine encoding ST. In ST-expressing tumor-bearing mice, this vaccine, pcDNA3-MCC/ST, generated a significant number of ST antigenic peptide-specific CD8+ T cells and experienced markedly enhanced survival compared to mice vaccinated with empty vector.

Conclusions: The formation of an effective vaccine against MCPyV has the potential to advance the field of MCC therapy and may contribute to the control of this severe malignancy through immunotherapy. Both of the innovative technologies presented here provide opportunities to develop and test MCPyV-targeted therapies for the control of Merkel cell carcinoma.

No MeSH data available.


Related in: MedlinePlus