Tenascin C Promotes Glioma Cell Malignant Behavior and Inhibits Chemosensitivity to Paclitaxel via Activation of the PI3K/AKT Signaling Pathway

Abstract

The present study aimed to detect the effect of tenascin C (TNC) on cell function and chemosensitivity to paclitaxel and phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling in glioma cells.Human glioma cells U87, LN-229, T98G and U251 and normal human astrocytes were obtained, in which TNC expression was detected. The U87 cells and U251 cells were chosen and infected with lentivirus of control overexpression, TNC overexpression, control knockdown, and TNC knockdown for functional experiments. Rescue experiments were then performed to evaluate the effect of PI3K/AKT activator 740 Y-P on cell function and chemosensitivity to paclitaxel in TNC knockdown U251 cells. TNC mRNA and protein expression was elevated in glioma cells, including U87, LN-229, U251 and T98G cells, compared to normal human astrocytes. In U87 and U251 cells, TNC promoted proliferation while inhibiting apoptosis. In addition, TNC upregulated PI3K and p-AKT protein expression in U87 and U251 cells. As for chemosensitivity, TNC increased relative viability in U251 cells treated with 400 ng/mL and 800 ng/mL paclitaxel. In terms of stemness, TNC increased the sphere number per 1000 cells, CD44⁺CD133⁺ cell percentage and 1/stem cell frequency (assessed by extreme limiting dilution analysis) in U251 cells. In rescue experiments, 740 Y-P reduced the effect of TNC on proliferation, apoptosis, chemosensitivity to paclitaxel, and stemness in U251 cells. TNC acts as an oncogenic factor by promoting cancer cell proliferation and stemness while inhibiting apoptosis and chemosensitivity to paclitaxel in glioma via modulation of PI3K/AKT signaling.

Keywords: Cell function; Chemosensitivity; Glioma; PI3K/AKT signaling; Tenascin C.

Fig. 1

mRNA and protein expression of TNC in glioma cells. Comparison of TNC mRNA (a) and protein (b) expression between glioma cells, including U87, LN-229, U251 and T98G cells, and normal human astrocytes as control. TNC tenascin C; GAPDH glyceraldehyde-phosphate dehydrogenase

Fig. 2

mRNA and protein expression of TNC in glioma cells after lentivirus infection. TNC mRNA (a) and protein (b) expression among the OE-NC, OE-TNC, KD-NC and KD-TNC groups in U251 cells. TNC mRNA (c) and protein (d) expression among the OE-NC, OE-TNC, KD-NC and KD-TNC groups in U87 cells. TNC tenascin C; OE overexpression; NC negative control; KD knockdown; GAPDH glyceraldehyde-phosphate dehydrogenase

Fig. 3

Cell proliferation and apoptosis regulated by TNC in glioma cells. The OD value (a) and cell apoptosis percentage (b, c) among the OE-NC, OE-TNC, KD-NC and KD-TNC groups in U251 cells. OD value (d) and cell apoptosis percentage (e, f) among the OE-NC, OE-TNC, KD-NC and KD-TNC groups in U87 cells. TNC tenascin C; OD optical density; CCK-8 cell-counting kit-8; OE overexpression; NC negative control; KD knock down

Fig. 4

PI3K/AKT signaling regulated by TNC in glioma cells. PI3K, AKT and p-AKT protein expression among the OE-NC, OE-TNC, KD-NC and KD-TNC groups in U251 cells (a) and U87 cells (b). PI3K phosphatidylinositol 3-kinase; AKT protein kinase B; p-AKT phosphorylated-AKT; TNC tenascin C; OE overexpression; NC negative control; KD knockdown; GAPDH glyceraldehyde-phosphate dehydrogenase

Fig. 5

Chemosensitivity to paclitaxel and stemness regulated by TNC in glioma cells. Relative cell viability (a), sphere number per 1000 cells (b), and CD44⁺CD133⁺ cell percentage (c, d) among the OE-NC, OE-TNC, KD-NC and KD-TNC groups in U251 cells. TNC tenascin C; OE overexpression; NC negative control; KD knockdown

Fig. 6

Effect of PI3K/AKT activator on proliferation and apoptosis in TNC knockdown glioma cells. PI3K, AKT and p-AKT protein expression (a), OD value (b) and cell apoptosis percentage (c, d) among the KD-NC, KD-TNC, KD-NC&740 Y-P and KD-TNC&740 Y-P groups in U251 cells. PI3K phosphatidylinositol 3-kinase; AKT protein kinase B; TNC tenascin C; p-AKT phosphorylated-AKT; OD optical density; CCK-8 cell counting kit-8; KD knockdown; NC negative control; GAPDH glyceraldehyde-phosphate dehydrogenase

Fig. 7

Effect of PI3K/AKT activator on chemosensitivity to paclitaxel and stemness in TNC knockdown glioma cells. U251 cell relative cell viability (a), sphere number per 1000 cells (b) and CD44⁺CD133⁺ cell percentage (c, d) among the KD-NC, KD-TNC, KD-NC&740 Y-P and KD-TNC&740 Y-P groups. PI3K phosphatidylinositol 3-kinase; AKT protein kinase B; TNC tenascin C; KD knockdown; NC negative control