Melphalan-induced up-regulation of B7-1 surface expression on normal splenic B cells

Cancer Immunol Immunother. 2003 Mar;52(3):162-70. doi: 10.1007/s00262-002-0345-8. Epub 2003 Feb 6.

Abstract

We have previously shown that exposure of MOPC-315 or P815 tumor cells to the widely used anticancer drug melphalan ( L-PAM, L-phenylalanine mustard) leads to rapid up-regulation of B7-1 surface expression. Since B7-1-expressing tumor cells depend on B7-expressing host antigen presenting cells (APC) for the generation of CD8(+) T-cell-mediated antitumor immunity, and since L-PAM promotes the acquisition of tumor-eradicating immunity by CD8(+) T-cells from MOPC-315 tumor bearers, the current studies were undertaken to determine if L-PAM also up-regulates B7-1 expression on host APC. Here we show that exposure of normal spleen cells to L-PAM leads within 24 h to up-regulated B7-1 expression on B220(+) cells (B cells). Studies into the mechanism through which L-PAM leads to up-regulated B7-1 expression revealed that within 2 h after exposure of normal spleen cells to L-PAM, accumulation of B7-1 mRNA is evident and this accumulation requires de novo RNA synthesis, indicating that the regulation is at the transcriptional level. The L-PAM-induced accumulation of B7-1 mRNA was prevented with the antioxidant N-acetyl- L-cysteine (NAC), indicating that reactive oxygen species are important for the transcriptional regulation. Although AP-1 and NF-kappa B are considered redox-sensitive transcription factors, L-PAM led only to activation of NF-kappa B that bound specifically to a probe containing the corresponding binding site in the B7-1 gene. Moreover, selective inhibition of NF-kappa B activation prevented the L-PAM-induced B7-1 mRNA accumulation, indicating that NF-kappa B activation is essential for L-PAM-induced B7-1 gene expression in normal spleen cells. Finally, in vivo administration of an immunopotentiating dose of L-PAM to normal mice was found to up-regulate B7-1 mRNA expression in their spleens. Thus, the ability of L-PAM to up-regulate B7-1 expression not only on tumor cells but also on host cells may contribute to the potentiating activity of L-PAM for the acquisition of CD8(+) T-cell-mediated tumor-eradicating immunity in tumor bearers.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antineoplastic Agents, Alkylating / pharmacology*
  • Antioxidants / pharmacology
  • B-Lymphocytes / metabolism*
  • B7-1 Antigen / biosynthesis*
  • Binding Sites
  • CD8-Positive T-Lymphocytes / metabolism
  • Cell Membrane / metabolism*
  • Cell Nucleus / metabolism
  • Dactinomycin / pharmacology
  • Flow Cytometry
  • Melphalan / pharmacology*
  • Mice
  • NF-kappa B / metabolism
  • Oxidation-Reduction
  • Protein Synthesis Inhibitors / pharmacology
  • RNA, Messenger / metabolism
  • Reactive Oxygen Species
  • Reverse Transcriptase Polymerase Chain Reaction
  • Spleen / cytology*
  • Spleen / drug effects
  • Spleen / immunology
  • Spleen / metabolism
  • Time Factors
  • Transcription Factor AP-1 / metabolism
  • Up-Regulation*

Substances

  • Antineoplastic Agents, Alkylating
  • Antioxidants
  • B7-1 Antigen
  • NF-kappa B
  • Protein Synthesis Inhibitors
  • RNA, Messenger
  • Reactive Oxygen Species
  • Transcription Factor AP-1
  • Dactinomycin
  • Melphalan