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Prostate stem cell antigen DNA vaccination breaks tolerance to self-antigen and inhibits prostate cancer growth.

ABSTRACT: Prostate stem cell antigen (PSCA) is a cell surface antigen expressed in normal human prostate and over expressed in prostate cancer. Elevated levels of PSCA protein in prostate cancer correlate with increased tumor stage/grade, with androgen independence and have higher expression in bone metastases. In this study, the PSCA gene was isolated from the transgenic adenocarcinoma mouse prostate cell line (TRAMPC1), and a vaccine plasmid construct was generated. This plasmid PSCA (pmPSCA) was delivered by intramuscular electroporation (EP) and induced effective antitumor immune responses against subcutaneous TRAMPC1 tumors in male C57 BL/6 mice. The pmPSCA vaccination inhibited tumor growth, resulting in cure or prolongation in survival. Similarly, the vaccine inhibited metastases in PSCA expressing B16 F10 tumors. There was activation of Th-1 type immunity against PSCA, indicating the breaking of tolerance to a self-antigen. This immunity was tumor specific and was transferable by adoptive transfer of splenocytes. The mice remained healthy and there was no evidence of collateral autoimmune responses in normal tissues. EP-assisted delivery of the pmPSCA evoked strong specific responses and could, in neoadjuvant or adjuvant settings, provide a safe and effective immune control of prostate cancer, given that there is significant homology between human and mouse PSCA.

SUBMITTER: Ahmad S

PROVIDER: S-EPMC2835175 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Prostate stem cell antigen DNA vaccination breaks tolerance to self-antigen and inhibits prostate cancer growth.

Ahmad Sarfraz S Casey Garrett G Sweeney Paul P Tangney Mark M O'Sullivan Gerald C GC

Molecular therapy : the journal of the American Society of Gene Therapy 20090331 6

Prostate stem cell antigen (PSCA) is a cell surface antigen expressed in normal human prostate and over expressed in prostate cancer. Elevated levels of PSCA protein in prostate cancer correlate with increased tumor stage/grade, with androgen independence and have higher expression in bone metastases. In this study, the PSCA gene was isolated from the transgenic adenocarcinoma mouse prostate cell line (TRAMPC1), and a vaccine plasmid construct was generated. This plasmid PSCA (pmPSCA) was delive ...[more]

PMID: 19337234

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Project description:The pivotal role of p53 as a tumor suppressor protein is illustrated by the fact that this protein is found mutated in more than 50% of human cancers. In most cases, mutations in p53 greatly increase the otherwise short half-life of this protein in normal tissue and cause it to accumulate in the cytoplasm of tumors. The overexpression of mutated p53 in tumor cells makes p53 a potentially desirable target for the development of cancer immunotherapy. However, p53 protein represents an endogenous tumor-associated antigen (TAA). Immunization against a self-antigen is challenging because an antigen-specific immune response likely generates only low affinity antigen-specific CD8(+) T-cells. This represents a bottleneck of tumor immunotherapy when targeting endogenous TAAs expressed by tumors. The objective of the current study is to develop a safe cancer immunotherapy using a naked DNA vaccine. The vaccine employs a xenogeneic p53 gene to break immune tolerance resulting in a potent therapeutic antitumor effect against tumors expressing mutated p53. Our study assessed the therapeutic antitumor effect after immunization with DNA encoding human p53 (hp53) or mouse p53 (mp53). Mice immunized with xenogeneic full length hp53 DNA plasmid intramuscularly followed by electroporation were protected against challenge with murine colon cancer MC38 while those immunized with mp53 DNA were not. In a therapeutic model, established MC38 tumors were also well controlled by treatment with hp53 DNA therapy in tumor bearing mice compared to mp53 DNA. Mice vaccinated with hp53 DNA plasmid also exhibited an increase in mp53-specific CD8(+) T-cell precursors compared to vaccination with mp53 DNA. Antibody depletion experiments also demonstrated that CD8(+) T-cells play crucial roles in the antitumor effects. This study showed intramuscular vaccination with xenogeneic p53 DNA vaccine followed by electroporation is capable of inducing potent antitumor effects against tumors expressing mutated p53 through CD8(+) T cells.

Dataset Information

Prostate stem cell antigen DNA vaccination breaks tolerance to self-antigen and inhibits prostate cancer growth.

Publications

Prostate stem cell antigen DNA vaccination breaks tolerance to self-antigen and inhibits prostate cancer growth.

Similar Datasets

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