Journal: Cancer Biology & Therapy
Article Title: USP44 promotes chemotherapeutic drug resistance of triple negative breast cancer through EZH2 protein stability
doi: 10.1080/15384047.2025.2529652
Figure Lengend Snippet: USP44 stabilizes EZH2 through deubiquitinase activity. (a) Extracts from MDA-MB-231 cells were isolated for co-immunoprecipitation using an anti-USP44 antibody or anti-EZH2 antibody. Specifically, MDA-MB-231 cells were lysed using RIPA and the lysates were pretreated with protein A/G beads at 4 C for one hour. The cell lysates were then treated with protein A/G beads containing anti-USP44 (5 µg) or anti-EZH2 (5 µg) antibodies at 4°C overnight. Then, the supernatant was discarded and loading buffer was added to crack the magnetic beads. The interaction of endogenous USP44 and EZH2 was tested. Normal mouse IgG was used as a control. (b) BT-549 cells with or without OE-USP44 were treated with CHX (25 µg/mL) and harvested at the indicated times (0,2,4,8 hours), then protein levels of USP44 amd EZH2 were analyzed by western blot. (c) Similarly, the same BT-549 cells with or without shUSP44 were treated as above, then protein levels of USP44 amd EZH2 were analyzed by western blot. (d) BT-549 cells with or without shUSP44 were treated with or without MG132 (1 μM) for 24 hours. The protein expression levels of USP44 and EZH2 were confirmed followed by western blot. β-actin was used as the loading control. (e) pLent-puro-ubiquitin plasmids was transfected into BT-549 cells with or without OE-USP44. After continuing to incubate for 48 h, the cells were lyzed with RIPA lysate and MG132 (10 μM) was added 2 hours before this step. Then the lysates were pretreated with protein A/G beads at 4 C for one hour. The cell lysates were then treated with protein A/G beads containing anti-EZH2 (5 µg) antibody at 4°C overnight. Then, the supernatant was discarded and loading buffer was added to crack the magnetic beads. USP44 ubiquitination was detected by western blot with anti-UB antibody. The protein expression levels of USP44 and EZH2 in BT-549 cells were confirmed. Boxplots are shown as mean ± SD. * p < .05; ** p < .01; *** p < .001.
Article Snippet: The antibodies used in this study include mouse anti-human USP44 (Santa cruz, sc -377,203), rabbit anti-human EZH2 (Proteintech 21,800–1-AP) for co-immunoprecipitation and mouse anti-human EZH2 (Abcam, ab283270), rabbit anti-human PARP1(Proteintech 13,371–1-AP), mouse anti human UB (CST, 3936), anti-FLAG tag (sigma, F1084) and rabbit anti-human β- Actin (Abclonal, AC026).
Techniques: Activity Assay, Isolation, Immunoprecipitation, Magnetic Beads, Control, Western Blot, Expressing, Ubiquitin Proteomics, Transfection
Proteintech is a verified supplier 
