Enhanced apoptosis mediates inhibition of EBV-transformed lymphoblastoid cell line proliferation by curcumin.
BACKGROUND
Epstein-Barr virus (EBV)-associated B-cell lymphomas occur more frequently in immunodeficient states such as organ transplantation and HIV infection. We have previously reported that B cell immortalization with EBV was promoted by cyclosporin A (CyA) and that curcumin (Cur), a natural phenol with known antioxidant and antitumor properties, blocked EBV-induced B cell immortalization. In the following experiments we show that Cur inhibits the proliferation of EBV-transformed lymphoblastoid cell lines (LCL) via enhanced apoptosis.


METHODS
LCL were generated by infecting freshly isolated human B cells with EBV (B95-8) for 12 h and coculturing with predetermined optimal concentrations of CyA (500 ng/ml) for 4 weeks. LCL were then either frozen for future use or propagated for immediate experiments. These cells were then plated in 96-well plates with 20 microM Cur or 0.1% DMSO (vehicle control). The number of immortalized colonies/well, cell count, and (3)H uptake were used as an index of immortalization. To assess apoptosis rate LCL were cultured with 0.1% DMSO or Cur (20 microM) for 0, 18, and 42 h in culture flasks and then stained with MC540 and H33342, as markers for apoptosis, and analyzed by FACS.


RESULTS
A profound inhibition of proliferation was seen in the LCL with 20 microM curcumin compared to 0.1% DMSO control. The colony count reduced from 34.5 +/- 3.4 to 0/well (P = 0.005), cell number reduced from 101,250 +/- 12,093 to 3750 +/- 1500/well (P = 0.002), and (3)H uptake reduced from 40,889 +/- 3669 to 70 +/- 5.2/well (P = 0.001). The apoptosis rate of LCL in the DMSO control at 24.07 and 16.87% increased significantly with 20 microM Cur to 76.4 and 95.1% at 18 and 42 h, respectively (P = 0.02).


CONCLUSIONS
Cur is a potent inhibitor of EBV-transformed LCL. This effect appears to be mediated through enhanced apoptosis. A further investigation of this effect may be useful in prevention and therapy of B-cell lymphoma in immunodeficient patients.
Ranjan
D
D
Department of Surgery, University of Kentucky, Lexington, Kentucky 40536, USA.
Johnston
T D
TD
Reddy
K S
KS
Wu
G
G
Bondada
S
S
Chen
C
C
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001402:B-Lymphocytes / Q000187:drug effects* / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D002461:Cell Line, Transformed; D003474:Curcumin / Q000494:pharmacology*; D004854:Herpesvirus 4, Human; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects*; D016393:Lymphoma, B-Cell / Q000188:drug therapy*
D000970:Antineoplastic Agents; D003474:Curcumin