title: Shikonin enhances efficacy of a gene-based cancer vaccine via induction of RANTES.
abstract: BACKGROUND
  Shikonin, a phytochemical purified from Lithospermum erythrorhizon, has been shown to confer diverse pharmacological activities, including accelerating granuloma formation, wound healing, anti-inflammation and others, and is explored for immune-modifier activities for vaccination in this study. Transdermal gene-based vaccine is an attractive approach for delivery of DNA transgenes encoding specific tumor antigens to host skin tissues. Skin dendritic cells (DCs), a potent antigen-presenting cell type, is known to play a critical role in transmitting and orchestrating tumor antigen-specific immunities against cancers. The present study hence employs these various components for experimentation.
  
  
  METHODS
  The mRNA and protein expression of RANTES were detected by RT-PCR and ELISA, respectively. The regional expression of RANTES and tissue damage in test skin were evaluated via immunohistochemistry assay. Fluorescein isothiocyanate sensitization assay was performed to trace the trafficking of DCs from the skin vaccination site to draining lymph nodes. Adjuvantic effect of shikonin on gene gun-delivered human gp100 (hgp100) DNA cancer vaccine was studied in a human gp100-transfected B16 (B16/hgp100) tumor model.
  
  
  RESULTS
  Among various phytochemicals tested, shikonin induced the highest level of expression of RANTES in normal skin tissues. In comparison, mouse RANTES cDNA gene transfection induced a higher level of mRANTES expression for a longer period, but caused more extensive skin damage. Topical application of shikonin onto the immunization site before gene gun-mediated vaccination augmented the population of skin DCs migrating into the draining lymph nodes. A hgp100 cDNA gene vaccination regimen with shikonin pretreatment as an adjuvant in a B16/hgp100 tumor model increased cytotoxic T lymphocyte activities in splenocytes and lymph node cells on target tumor cells.
  
  
  CONCLUSIONS
  Together, our findings suggest that shikonin can effectively enhance anti-tumor potency of a gene-based cancer vaccine via the induction of RANTES expression at the skin immunization site.
authors.affiliation: Department and Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Hui-Ming
authors.initials: HM
authors.lastname: Chen
authors.forename: Pi-Hsueh
authors.initials: PH
authors.lastname: Wang
authors.forename: Kandan
authors.initials: K
authors.lastname: Aravindaram
authors.forename: Yun-Hsiang
authors.initials: YH
authors.lastname: Chen
authors.forename: Hsiu-Hui
authors.initials: HH
authors.lastname: Yu
authors.forename: Wen-Chin
authors.initials: WC
authors.lastname: Yang
authors.forename: Ning-Sun
authors.initials: NS
authors.lastname: Yang
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D019496:Cancer Vaccines / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D018946:Chemokine CCL5 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D009285:Naphthoquinones / Q000494:pharmacology*; D012878:Skin Neoplasms / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000628:therapy; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D058951:gp100 Melanoma Antigen / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; C483024:CCL5 protein, human; D019496:Cancer Vaccines; C503460:Ccl5 protein, mouse; D018946:Chemokine CCL5; D009285:Naphthoquinones; D019444:Vaccines, DNA; D058951:gp100 Melanoma Antigen; C016101:shikonin