Mitomycin C induces bystander killing in homogeneous and heterogeneous hepatoma cellular models.
BACKGROUND
Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide that is particularly refractory to chemotherapy. Several studies have proposed combination chemotherapy regimen for HCC treatment. However, these therapies are not effective in regressing tumor and prolonging survival of patient's suffering from HCC. Therefore, the development of more effective therapeutic tools and new strategies for the treatment of HCC are urgently needed. Over the last decade much attention has been focused on "bystander effect" as a possible therapeutic strategy for the treatment of certain human tumors. Interest in this therapeutic approach originated from numerous reports describing the radiation induced bystander effect. However, the knowledge about chemotherapy induced bystander effect is still limited. Hence, chemotherapy induced bystander phenomenon in hepatoma cells was explored by utilizing Mitomycin C (MMC).


RESULTS
MMC induced bystander killing was observed only in hepatoma cells and it did not occur in cervical cancer cells. MMC induced bystander killing was transferable via medium. It occurred in co-cultured cells indicating the involvement of secreted as well as membrane bound factors. FasL and TRAIL were detected in the conditioned medium from treated cells. In medium transfer experiment, pre-treatment with EDTA (a broad range protease inhibitor) diminished MMC induced bystander killing. Following drug exposure, expression of Fas and TRAIL receptors increased and treatment with neutralizing antibodies against FasL and TRAIL inhibited bystander killing.


CONCLUSIONS
Our results highlight the therapeutic importance of MMC in the treatment of HCC and implicate role of membrane bound and secreted forms of FasL and TRAIL in MMC induced bystander killing.
National Centre for Cell Science, Ganeshkhind, Pune- 411 007, India. ratnabt@yahoo.com
Ratna
R
Kumari
Aanchal
A
Sharma
Amrendra Kumar
AK
Ajay
Manoj Kumar
MK
Bhat
D024201:Bystander Effect / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D002452:Cell Count; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D018920:Coculture Techniques; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D004492:Edetic Acid / Q000494:pharmacology; D005260:Female; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008113:Liver Neoplasms / Q000473:pathology*; D016685:Mitomycin / Q000494:pharmacology*; D008954:Models, Biological; D053218:Receptors, Death Domain / Q000378:metabolism; D014410:Tumor Stem Cell Assay; D002583:Uterine Cervical Neoplasms / Q000473:pathology
D003470:Culture Media; D008024:Ligands; D053218:Receptors, Death Domain; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D016685:Mitomycin; D004492:Edetic Acid