Combination therapy with epigallocatechin-3-gallate and doxorubicin in human prostate tumor modeling studies: inhibition of metastatic tumor growth in severe combined immunodeficiency mice.
The polyphenol epigallocatechin-3-gallate (EGCG) in combination with doxorubicin (Dox) exhibits a synergistic activity in blocking the growth and colony-forming ability of human prostate cell lines in vitro. EGCG has been found to disrupt the mitochondrial membrane potential, induce vesiculation of mitochondria, and induce elevated poly (ADP-ribose) polymerase (PARP) cleavage and apoptosis. EGCG in combination with low levels of Dox had a synergistic effect in blocking tumor cell growth. In vivo tumor modeling studies with a highly metastatic tumor line, PC-3ML cells, revealed that EGCG (228 mg/kg or 200 μmol/L) appeared to sensitize tumors to Dox. EGCG combined with low levels of Dox (0.14 mg/kg or 2 μmol/L) blocked tumor growth by PC-3ML cells injected intraperitoneally (ie, in CB17 severe combined immunodeficiencies) and significantly increased mouse survival rates. Similarly, relatively low levels of EGCG (57 mg/kg or 50 μmol/L) plus Dox (0.07 mg/kg or 1 μmol/L) eradicated established tumors (ie, in nonobese diabetic-severe combined immunodeficiencies) that were derived from CD44(hi) tumor-initiating cells isolated from PCa-20a cells. Flow cytometry results showed that EGCG appeared to enhance retention of Dox by tumor cells to synergistically inhibit tumor growth and eradicate tumors. These data suggest that localized delivery of high dosages of EGCG combined with low levels of Dox may have significant clinical application in the treatment of metastatic prostate and/or eradication of primary tumors derived from tumor-initiating cells.
Stearns
Mark E
ME
Drexel University College of Medicine, Dept. of Pathology, MS 435, 245 N. Broad St., Philadelphia, PA 19102, USA. stearnsm1@aol.com
Amatangelo
Michael D
MD
Varma
Devika
D
Sell
Chris
C
Goodyear
Shaun M
SM
D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002277:Carcinoma / Q000188:drug therapy* / Q000473:pathology; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004317:Doxorubicin / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D009362:Neoplasm Metastasis; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
D004317:Doxorubicin; D002392:Catechin; C045651:epigallocatechin gallate