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Modulation of murine neuroblastoma in nude mice by opioid antagonists
Abstract:
Naltrexone, an opioid antagonist, had an inhibitory effect on the growth of murine S20Y neuroblastoma in BALB/c nude mice. Daily injections of 0.1 mg naltrexone/kg, which invoked a receptor blockade for 6-8 hours/day, resulted in 31-92% delay in latency time prior to tumor expression and a 27-49% increase in mean survival time; the magnitude of antitumor response was governed by tumor burden. Inoculation of neuroblastoma (10(6)-2.5 X 10(4) cells) resulted in measurable tumors in 10-13 days and mean survival times of 30-34 days. Immunoreactive beta-endorphin was detected in tumor tissue (39.7 pg/mg protein). Receptor binding assays revealed specific saturable binding of ligands related to delta- and kappa-binding sites, but not for the mu-binding site. These results demonstrate that opioid antagonist modulation of neuro-oncogenesis is not dependent on the integrity of T-cell-mediated immunity and suggest the feasibility of utilizing the nude mouse model in exploring the role of endogenous opioids in human cancers.
Insights
Naltrexone, an opioid antagonist, inhibited neuroblastoma growth in mice. This treatment delayed tumor appearance and increased survival time, showing potential for cancer research.
Area of Science:
- Neuro-oncology
- Pharmacology
- Immunology
Background:
- Opioid antagonists like naltrexone may influence cancer development.
- Neuroblastoma is a pediatric cancer with complex growth mechanisms.
- The role of endogenous opioids in cancer is not fully understood.
Purpose of the Study:
- To investigate the effect of naltrexone on neuroblastoma growth in a murine model.
- To determine if opioid receptor blockade impacts tumor latency and survival.
- To explore the potential of using nude mice for studying opioid roles in human cancers.
Main Methods:
- Murine S20Y neuroblastoma cells were inoculated into BALB/c nude mice.
- Daily injections of naltrexone (0.1 mg/kg) were administered.
- Tumor latency, mean survival time, and opioid receptor binding were analyzed.
Main Results:
- Naltrexone significantly delayed tumor onset (31-92%) and increased mean survival time (27-49%).
- The antitumor effect correlated with tumor burden.
- Beta-endorphin was detected in tumor tissue, with binding to delta- and kappa-opioid receptors.
Conclusions:
- Opioid antagonist treatment can inhibit neuroblastoma growth independently of T-cell immunity.
- Naltrexone demonstrates potential as a therapeutic agent or research tool in neuro-oncology.
- The nude mouse model is suitable for investigating endogenous opioids in human cancer.