Expression of the melatonin receptor (MT) 1 in benign and malignant human bone tumors
Cyril D Toma1, Martin Svoboda, Ferdi Arrich
1Department of Orthopaedic Surgery, Medical University of Vienna, Vienna, Austria.
Abstract:
The beneficial effects of melatonin on bone homeostasis have been shown in various diseases. As this indoleamine causes dose-dependent modulation of bone-forming osteoblast and bone-resorbing osteoclast activities by receptor-independent and -dependent pathways, we investigated the expression of G-protein-coupled melatonin receptors (MTs) in malignant and non-malignant human bone lesions. By TaqMan polymerase chain reaction (PCR), we analyzed 30 specimens from osteosarcoma and 11 from benign bone tumors for MT1-mRNA expression. Furthermore, we determined mRNA expression levels of the osteoclast activity-stimulating receptor activator of nuclear factor-kappa B ligand (RANKL) and its counterpart osteoprotegerin (OPG). Although mean MT1-mRNA levels were similar (P = 0.596) in malignant (4.39 +/- 4.98-fold) and benign samples (4.64 +/- 6.81-fold), the highest MT1-mRNA levels (up to 27-fold) were observed in individual osteosarcomas, particularly, in two specimens of patients with local recurrence of the tumor. Moreover, mean RANKL- and OPG-mRNA levels were similar in malignant and benign specimens (RANKL: 7.38 +/- 9.61-fold versus 3.57 +/- 3.11-fold, P = 0.207; OPG: 23.45 +/- 32.76 versus 8.07 +/- 7.23-fold, P = 0.133). Again, highest RANKL- and OPG-mRNA levels (up to 41- and 160-fold, respectively) were observed in individual osteosarcomas. Expression of MT1-mRNA was confirmed in two human osteosarcoma cell lines (HOS, MG63). High expression levels of MT1-mRNA together with low OPG-mRNA were found in both osteosarcoma cell lines, while in normal human osteoblasts and bone marrow stromal cells, high OPG-mRNA levels were associated with low MT1-mRNA levels. These data on the abundant expression of MT1-mRNA in human bone tumors and osteosarcoma cells lines suggest an important role for MT1 in bone pathology.
Insights
Melatonin receptors (MTs) are expressed in human bone tumors, with high MT1-mRNA levels found in osteosarcoma cell lines. This suggests a significant role for MT1 in bone pathology and tumor development.
Area of Science:
- Bone biology
- Endocrinology
- Oncology
Background:
- Melatonin influences bone homeostasis through osteoblast and osteoclast modulation.
- G-protein-coupled melatonin receptors (MTs) mediate these effects.
- Understanding MT expression in bone tumors is crucial for therapeutic insights.
Purpose of the Study:
- To investigate the expression of MT1-mRNA in malignant and non-malignant human bone lesions.
- To analyze mRNA levels of RANKL and OPG in these bone tumors.
- To explore the correlation between MT1, RANKL, and OPG expression in osteosarcoma.
Main Methods:
- TaqMan polymerase chain reaction (PCR) was used to analyze MT1-mRNA expression.
- 30 osteosarcoma and 11 benign bone tumor specimens were examined.
- mRNA expression of RANKL and OPG was also quantified.
Main Results:
- Mean MT1-mRNA levels were similar in malignant and benign bone tumors, but highest levels were found in individual osteosarcomas, especially those with local recurrence.
- RANKL and OPG mRNA levels were also similar between malignant and benign groups, with highest levels observed in individual osteosarcomas.
- Osteosarcoma cell lines (HOS, MG63) showed high MT1-mRNA and low OPG-mRNA expression, contrasting with normal osteoblasts.
Conclusions:
- Abundant MT1-mRNA expression in human bone tumors and osteosarcoma cell lines suggests a significant role for MT1 in bone pathology.
- The differential expression of MT1 and OPG in osteosarcoma cell lines compared to normal cells warrants further investigation.
- These findings may open new avenues for melatonin-based therapeutic strategies in bone tumors.
