Figure 6: Acetylation of Beclin 1 promotes tumour cell proliferation and tumorigenesis in vivo.

(a) Beclin 1–2KR mutant inhibits cell proliferation. MCF7 cells stably expressing vector control, Beclin 1 WT or 2KR were seeded at the same number in each well. Then made CCK-8 assay every 24 h. Results are mean±s.d. for experiments performed in triplicate, **P<0.01 (Student’s t-test). (b) MCF7 cells stably expressing vector control, Beclin 1 WT or 2KR were used for colony formation assays. Cells (0.5 × 10⁴) were grown in soft agar, and the colonies were monitored after 2 weeks. Representative pictures of the colonies are shown. Results from three independent experiments are presented as means±s.d., *P<0.05 (Student’s t-test). (d) Beclin 1–2KR mutant inhibits xenograft tumour growth. MCF7 cell lines (6 × 10⁶ cells) with vector control, Beclin 1 WT or 2KR were injected subcutaneously into the right flank of nude mice. At 38 days after injection, tumours were extracted and photographed. (e) Tumour growth curves in nude mice. Tumour diameters were measured at the indicated time points, and tumour volumes were calculated. Results are mean volume±s.e.m. for 10 mice per group per time point. *P<0.05 (Student’s t-test). (f) Tumour weights from experiment in c on autopsy on day 38. *P<0.05 (Student’s t-test). (g) Beclin 1–2KR expression inhibits tumour cell proliferation in vivo. Tumour sections from xenografts were prepared for immunohistochemistry analysis. Representative haematoxylin and eosin staining (H&E) and Ki-67, p62, EGFR immunostaining images of indicated MCF7 xenograft tumour genotype. Scale bars, 20 μm.