Bcl-2 and glutathione depletion sensitizes B16 melanoma to combination therapy and eliminates metastatic disease.
OBJECTIVE
Advanced melanoma resists all current therapies, and metastases in the liver are particularly problematic. Prevalent resistance factors include elevated glutathione (GSH) and increased expression of bcl-2 in melanoma cells. GSH has pleiotropic effects promoting cell growth and broad resistance to therapy, whereas Bcl-2 inhibits the activation of apoptosis and contributes to elevation of GSH. This study determined the in vivo efficacy of combination therapies administered while GSH and Bcl-2 were individually and simultaneously decreased in metastatic melanoma lesions.


METHODS
Highly metastatic murine B16 melanoma (B16M-F10) cells have elevated levels of both GSH and Bcl-2. B16M-F10 cells were injected i.v. to establish metastatic lesions in vivo. GSH was decreased using an L-glutamine--enriched diet and administration of verapamil and acivicin, whereas Bcl-2 was reduced using oligodeoxynucleotide G3139. Paclitaxel, X-rays, tumor necrosis factor-alpha, and IFN-gamma were administered as a combination therapy.


RESULTS
Metastatic cells were isolated from liver to confirm the depletion of GSH and Bcl-2 in vivo. Reduction of Bcl-2 and GSH, combined with partial therapies, decreased the number and volume of invasive B16M-F10 foci in liver by up to 99% (P<0.01). The full combination of paclitaxel, X-rays, and cytokines eliminated B16M-F10 cells from liver and all other systemic disease, leading to long-term survival (>120 days) without recurrence in 90% of mice receiving the full therapy. Toxicity was manageable; the mice recovered quickly, and hematology and clinical chemistry data were representative of accepted clinical toxicities.


CONCLUSIONS
Our results suggest a new strategy to induce regression of late-stage metastatic melanoma.
Mena
Salvador
S
Department of Physiology, Faculty of Medicine and Odontology, University of Valencia, Valencia, Spain.
Benlloch
María
M
Ortega
Angel
A
Carretero
Julian
J
Obrador
Elena
E
Asensi
Miguel
M
Petschen
Ignacio
I
Brown
Bob D
BD
Estrela
José M
JM
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D005973:Glutamine / Q000008:administration & dosage; D005978:Glutathione / Q000037:antagonists & inhibitors*; D008546:Melanoma, Experimental / Q000188:drug therapy / Q000532:radiotherapy / Q000628:therapy*; D051379:Mice; D009362:Neoplasm Metastasis; D017239:Paclitaxel / Q000627:therapeutic use*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors* / Q000235:genetics; D012878:Skin Neoplasms / Q000188:drug therapy / Q000532:radiotherapy / Q000628:therapy*; D013873:Thionucleotides / Q000494:pharmacology; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000627:therapeutic use*; D014965:X-Rays
D000972:Antineoplastic Agents, Phytogenic; D019253:Proto-Oncogene Proteins c-bcl-2; D013873:Thionucleotides; D014409:Tumor Necrosis Factor-alpha; D005973:Glutamine; C408162:oblimersen; D005978:Glutathione; D017239:Paclitaxel