Journal: Molecular Oncology
Article Title: Reversing tozasertib resistance in glioma through inhibition of pyruvate dehydrogenase kinases
doi: 10.1002/1878-0261.13025
Figure Lengend Snippet: Sustained exposure to tozasertib promotes PDK expression and inhibits PDH activity. (A) Whole cell extracts from drug‐naïve, or cells treated with tozasertib for 72 h (short‐term), or tozasertib‐resistant cells were prepared. Twenty micrograms of protein were separated on a SDS/PAGE. Western blot analysis was performed with the indicated antibodies. Expression of β‐actin served as a loading control. These experiments were performed at least three times, and a representative blot is presented here. (B) Whole cell extracts from drug‐naïve or tozasertib‐resistant cells were subjected to PDH activity assay and reported as PDH activity·min −1 ·mL −1 . The values are represented as mean ± standard deviation of three independent experiments (statistical analysis was carried out with an unpaired two‐tailed t ‐test; ** P < 0.005, *** P < 0.0001). (C–E) Drug‐naïve or tozasertib‐resistant adult (U87) and pediatric (SJG2 and SF8628) glioma cell lines were treated with 10 µmol·L −1 of PDK4‐IN‐1 hydrochloride (C) or 10 µmol·L −1 of VER‐246608 (D) or 1 mmol·L −1 DCA (E) for 72 h. Vehicle (DMSO) treated cells served as control. Seventy‐two hours later, cell growth was assessed by MTS assay. Absorbance was recorded at 490 nm using a Synergy HTX multimode microplate reader. The values are represented as mean ± standard deviation of three separate experiments (= four wells per condition). Data (C–E) were analyzed for statistical significance by Tukey's ANOVA (NS, not significant, * P < 0.01, *** P < 0.0005). (F, G) Logarithmically growing U87, SJG2, and SF8628 drug naïve or tozasertib‐resistant cells were transfected with empty vector or PDK4 expression plasmid. Forty‐eight hours after infection, cells were washed, lifted, and lysed. Equal amount of protein was separated on a SDS/PAGE and western blot analysis was performed with PDK4 antibody. Expression of β‐actin served as a loading control. These experiments were performed at least three times, and a representative blot (F, upper panel) is presented here. In parallel, cell lysates were analyzed for PDH activity and reported as fold change relative to control (F, lower panel). Data are the mean ± SD of three independent experiments (*** P < 0.0005, data analyzed for statistical significance by unpaired two‐tailed t ‐test). (G) Vector or PDK4‐transfected cells were treated with or without tozasertib (100 nmol·L −1 ) for 72 h. Vehicle (DMSO) treated cells served as control. Cell growth was assessed by spectrophotometric measurement of MTS bioreduction using a microplate reader ( n = 4 wells per condition). Data point represents the mean ± SD of three measurements. Statistical analysis was carried out with Tukey's ANOVA (** P < 0.001, *** P < 0.0001).
Article Snippet: For transient transfection, commercially available ON‐TARGET‐plus siRNAs for human aurora kinase A (siRNA‐1, J‐003545‐26‐0002 and siRNA‐2, J‐003545‐27‐0002); aurora kinase B (siRNA‐1, J‐003326‐21‐0002 and siRNA‐2, J‐003326‐22‐0002); aurora kinase C (siRNA‐1, J‐019573‐11‐0002 and siRNA‐2, J‐019573‐13‐0002); and non‐target control siRNA (NT‐siRNA, D‐001830‐01‐05) sequences were used and transfected following the manufacturer's protocol (Dharmacon, Lafayette, CO, USA). pCMV‐6 vector (catalog number PS100001) and PDK4 (catalog number CW306843) expression plasmids obtained from Origene (Rockville, MD, USA) were used for overexpression analysis as reported previously [ , ].
Techniques: Expressing, Activity Assay, SDS Page, Western Blot, Control, Standard Deviation, Two Tailed Test, MTS Assay, Transfection, Plasmid Preparation, Infection