Figure 4

Valproic acid potentiated temsirolimus to trigger Burkitt leukemia/lymphoma (BL) cell autophagy through inhibiting HDAC1. (A) Valproic acid (VPA), either alone or in combination, inhibited HDAC1 expression (upper panel), in parallel with decreased HDAC1 enzymatic activity (lower panel), but increased CDKN1A and CDKN1B expression (upper panel). (B) Comparing with the negative control (CON siRNA), VPA failed to alter CDKN1A, CDKN1B, or LC3-I/II expression in Namalwa cells transfected with HDAC1 siRNA. (C and D) HDAC1 siRNA abrogated VPA-induced inhibition of tumor cell growth (C, *P<0.05 comparing with CON siRNA) and induction of autophagy (D, as detected by immunefluorescence study on BECN1 and P62).