Anticancer Effect of Cathelicidin LL-37, Protegrin PG-1, Nerve Growth Factor NGF, and Temozolomide: Impact on the Mitochondrial Metabolism, Clonogenic Potential, and Migration of Human U251 Glioma Cells

Abstract

Glioblastoma (GBM) is one of the most aggressive and lethal malignancy of the central nervous system. Temozolomide is the standard of care for gliomas, frequently results in resistance to drug and tumor recurrence. Therefore, further research is required for the development of effective drugs in order to guarantee specific treatments to succeed. The aim of current study was to investigate the effects of nerve growth factor (NGF), human cathelicidin (LL-37), protegrin-1 (PG-1), and temozolomide on bioenergetic function of mitochondria, clonogenicity, and migration of human U251 glioma cells. Colony formation assay was used to test the ability of the glioma cells to form colonies in vitro. The U251 glioma cells migration was evaluated using wound-healing assay. To study the mitochondrial metabolism in glioma cells we measured oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) using a Seahorse XF cell Mito stress test kit and Seahorse XF cell Glycolysis stress kit, respectively. We revealed that LL-37, NGF, and TMZ show strong anti-tumorigenic activity on GMB. LL-37 (4 μM), TMZ (155 μM), and NGF (7.55 × 10−3 μM) inhibited 43.9%–60.3%, 73.5%–81.3%, 66.2% the clonogenicity of glioma U251 cells for 1–2 days, respectively. LL-37 (4 μM), and NGF (7.55 × 10−3 μM) inhibited the migration of U251 glioma cells on the third and fourth days. TMZ also inhibited the migration of human glioma U251 cells over 1–3 days. In contrast, PG-1 (16 μM) stimulated the migration of U251 glioma cells on the second, fourth, and sixth days. Anti-mitogenic and anti-migration activities of NGF, LL-37, and TMZ maybe are relation to their capacity to reduce the basal OCR, ATP-synthetase, and maximal respiration of mitochondria in human glioma U251 cells. Glycolysis, glycolytic capacity and glycolytic spare in glioma U251 cells haven`t been changed under the effect of NGF, LL-37, PG-1, and TMZ in regard to control level. Thus, LL-37 and NGF inhibit migration and clonogenicity of U251 glioma cells, which may indicate that these compounds have anti-mitogenic and anti-migration effects on human glioma cells. The study of the mechanisms of these effects may contribute in the future to the use of NGF and LL-37 as therapeutic agents for gliomas.

Nerve Growth Factor, Antimicrobial Peptides and Chemotherapy: Glioblastoma Combination Therapy to Improve Their Efficacy

“…These results indicate stronger cytotoxic antitumor effects of these combinations. Probably, the cytotoxic effects of NGF in glioma U251 cells may be related to its capacity to inhibit the basal oxygen consumption rate, ATP-synthetase, maximal respiration of mitochondria, and migration of these cells [56]. NGF, through interaction with its specific receptors, the p75 neurotrophin receptor (p75NTR) and the tropomyosin-related kinase A (TrkA), regulates carcinogenesis by either suppressing or supporting tumor growth.…”

“…In the current study, we show that the IC50 of the combination of LL-37 with etoposide was lower than the IC50 of the chemotherapy drug alone, while the IC50 of the combinations of LL-37 with temozolomide, cisplatin, carboplatin, and doxorubicin was higher than the IC50 of the chemotherapy drugs. However, the combination of LL-37 with cisplatin in several doses (830, 332, 166, 83, 3.32 µM) and the combination of LL-37 with carboplatin at 2.69 mM had a more cytotoxic effect than the chemotherapy We have recently detected that the cytotoxic effects of LL-37 with temozolomide in glioma U251 cells can be associated with their capacity to inhibit clonogenicity, migration, basal oxygen consumption rate, ATP-synthetase, and maximal respiration of mitochondria in these cells [56].…”