Acridines are an important class of bioactive molecules having varied uses. Its derivative, 9-phenylacridine (ACPH) had been found to exhibit antitumor activity both in cell lines and
in vivo
model. Its DNA binding ability and absorbance in the ultraviolet range encouraged us to investigate its role as a photosensitizer with UVA radiation. We investigated the effects of ACPH prior to UVA exposure on
in vitro
DNA through photo-cleavage assay. Effect of such treatment was also studied in cultured A375 melanoma cells. Endpoints studied included morphological changes, evaluation of cellular viability, scratch assay, intracellular reactive oxygen species (ROS) production, DNA damage, lipid peroxidation, glutathione (GSH) level, autophagy, cell cycle progression, depletion of mitochondrial membrane potential (ΔΨmt), induction of apoptosis and Hoechst dye efflux assay. Our findings indicated that ACPH could sensitize damage to DNA induced by UVA both
in vitro
and in cells. It could also potentiate cell killing by UVA. It arrested cells in G
2
/M phase and induced apoptotic death through mitochondria mediated pathway. This sensitization was through enhancement of intracellular ROS. Our findings also indicated that the stem cells side population was reduced on such treatment. The findings are important as it indicates ACPH as a promising photosensitizer and indicates its possible role in photodynamic therapy.
Background:
Dental pulp-derived stem cells (DPSC) is a promising therapy as they modulate the immune response, so we evaluated the inhibitory effect of DPSC secretome (DPSC
℗
) on the proliferation and inflammation in human glioblastoma (GBM) cells (U-87 MG) and elucidated the concomitant mechanisms involved.
Methods:
The U87-MG cells were cultured with DPSC
℗
for 24 h and assessed the expression of inflammatory molecules using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), generation of reactive oxygen species (ROS), and mitochondrial functionality using a seahorse flux analyzer. MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay and cell cycle analysis were performed to evaluate the proliferation and cell cycle. Finally, the protein levels were determined by western blot.
Results:
DPSC
℗
reduced the inflammation and proliferation of U-87 MG cells by down-regulating the pro-inflammatory markers and up-regulating anti-inflammatory markers expressions through ROS-mediated signaling. Moreover, DPSC
℗
significantly reduced the mitochondrial membrane potential (MMP) in the cells. The cellular bioenergetics revealed that all the parameters of oxygen consumption rate (OCAR) and the extracellular acidification rate (ECAR) were significantly decreased in the GBM cells after the addition of DPSC
℗
. Additionally, DPSC
℗
decreased the GBM cell proliferation by arresting the cell cycle at the G1 phase through activation (phosphorylation) of checkpoint molecule CHK1. Furthermore, mechanistically, we found that the DPSC
℗
impedes the phosphorylation of the mitogen-activated protein kinases (P38 MAPK) and protein kinase B (AKT) pathway.
Conclusion:
Our findings lend the first evidence of the inhibitory effects of DPSC
℗
on proliferation and inflammation in GBM cells by altering the P38 MAPK-AKT pathway.
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