gms | German Medical Science

Objective: Carnosine (β-alanine-L-histidine) reduces the growth of glioblastoma cells in culture. Here, we investigated the specificity of the anti-neoplastic effect on proliferation and migration comparing glioblastoma cells and patient derived fibroblasts. In addition, we developed a culture model to analyze the migration of tumor cells into normal tissue.

Methods: Patient derived fibroblasts (FB) (13 cultures) and primary glioblastoma (GBM) cells (8 cultures) were cultivated in medium with different concentrations of carnosine. After 48 hours viability was assessed. Co-cultures were created using 12 well plates and cloning rings, placing GBM cells inside and patient derived FBs outside the cloning ring. Then, cultures were incubated in the absence or presence of carnosine for 3 weeks after which cells were stained. Colony formation and area occupancies of FBs and GBM cells were analyzed by microscopy and quantified using ImageJ.

Results: Both, FBs and GBM cells, respond to increased concentrations of carnosine with a reduced production of ATP although the effect was less pronounced in FBs (50 mM: FB: 95.3±5.4%; GBM: 88.3±8.2%; 75 mM: FB: 85.1±5.8%; GBM: 71.3±6.8%). A comparable observation was made by measuring dehydrogenase activities (50 mM: FB: 87.9±4.4%; GBM: 81.2±7.1%; 75 mM: FB: 78.8±5.0%; GBM: 61.8±4.8%). Co-culture experiments revealed that carnosine strongly inhibited the formation of tumor cell colonies within the fibroblast layer (85.8±50.5 in the absence of carnosine) compared to 46.6±26.4 (10 mM), 28.8±4.0 (25 mM) and 1.25±0.5 (50 mM). The tumor cell covered area was reduced from 13.4±3.9% (no carnosine) to 7.7±2.5% (10 mM), 6.0±3% (25 mM) and 3.1±3.2% (50 mM).

Conclusion: Although viability of FBs was reduced by carnosine the effect on GBM cells was more pronounced. More importantly, the dipeptide significantly inhibited colony formation and migration in a fibroblast co-culture model leading to a reduced number of tumor cell colonies without affecting fibroblast growth even at a concentration of 10 mM carnosine. Therefore, we assume that the long-term exposure to carnosine may strongly inhibit the occurrence of recurrent tumors if it would be possible to apply it directly into the excision cavity of surgically treated glioblastoma patients to prevent outspread of remaining tumor cells into the surrounding tissue.

In addition, the co-culture model presented can be a valuable tool for the analysis of drugs considered for the therapy of glioblastoma.