SNB-19

Cepharanthine Induces ROS Stress in Glioma and Neuronal Cells Via Modulation of VDAC Permeability

Cepharanthine (CEP) is a bisbenzylisoquinoline alkaloid that may influence the occurrence and development of glioblastoma multiforme (GBM) through Voltage-dependent anion channels (VDAC). Cierluk's team investigated the biological effects of CEP on the glioblastoma cell line (SNB-19) and neuron cell line (PC-12 + NGF), finding that CEP induces ROS stress in glioma and neuronal cells by modulating VDAC permeability. Immunocytochemical staining showed that T-type calcium channel expression in SNB-19 cells increased with higher CEP concentrations, peaking at 10 μM. CEP did not affect T-type channel expression in PC-12 + NGF cells. For VDAC, SNB-19 cells showed a steady increase in expression with higher CEP concentrations, but no time-dependent changes. PC-12 + NGF cells had higher VDAC expression levels at higher CEP concentrations compared to SNB-19 cells, and their initial VDAC expression was significantly higher (Fig. 1). Cells incubated with increasing CEP concentrations showed a rise in ROS levels, especially in SNB-19 cells (Fig. 2A). Over time, even lower CEP concentrations led to greater ROS generation. Upon CEP addition, mitochondrial content dispersed evenly in the cytoplasm compared to the concentrated pattern in controls. In PC-12+NGF cells, ROS release was significant after 24h incubation at lower CEP concentrations, showing a distribution pattern similar to SNB-19 cells (Fig. 2B).

Fig. 1. The immunocytochemical evaluation of calcium T-type channel (A) and VDAC (B) with ABC technique after 24 h and 72 h incubation with varying concentrations of CEP (Cierluk, K., Szlasa, W., et al., 2020).

Fig. 2. Immunofluorescent staining of ROS in SNB-19 cells (A) and PC-12 + NGF cells (B) after (a) 24 h and (b) 72 h of incubation with varying CEP concentrations (Cierluk, K., Szlasa, W., et al., 2020).

ZIKV Infection Reduced Mitochondrial Transmembrane Potential

Zika virus (ZIKV) causes neurodevelopmental disruption in newborn babies. Yang's team had studied how mitochondrial shape and function were altered in human NSCs and the human glioblastoma cell line SNB-19 following ZIKV infection. They explained how ZIKV infection disturbs mitochondrial dynamics, network organisation and activity by depleting MFN2 protein. In order to examine mitochondrial fragmentation under ZIKV infection, they speculated that dysregulation could be caused by a mismatch between mitochondrial fusion and fission proteins. In ZIKV-infected NSCs and SNB-19 cells, MFN2 protein levels fell after 24 hours even though infection was only 50 % (Fig. 3A-C). MFN1 reduction occurred in SNB-19 cells but not in NSCs, possibly due to lower neuronal expression (Fig. 3B). Immunofluorescence confirmed weaker MFN2 signals in infected cells compared to uninfected ones (Fig. 3D and E). Fragmented mitochondria were observed in ZIKV ENV-positive cells, indicating reduced mitochondrial fusion (Fig. 3F-H). Protein levels of OPA1, DNM1L, and FIS1 were unchanged, but DNM1L phosphorylation at Ser616, which promotes fission, was absent (Fig. 3B). This dephosphorylation could be a response to excessive fragmentation to curb further fission. Overall, ZIKV infection disrupted the balance of mitochondrial fusion and fission, leading to network fragmentation.

Fig. 3. MFN2 protein level was reduced in ZIKV-infected cells (Yang S, Gorshkov K, et al., 2020).