Figure 4.

STAT3 depletion by siRNA inhibits expression of DNMT1. (A) Expression of STAT3, DNMT1, and the other listed proteins after treatment of the T-cell lymphoma cell lines 2A and 2B for the indicated times with STAT3 siRNA or control, non–sense (NS) siRNA. Untreated PB-1 line served as an additional control. (B) STAT3 siRNA–mediated inhibition of cell growth of 2A cells as determined in the MTT enzymatic conversion assay. Time point (TP) 1 designates a single siRNA treatment at the experiment inception (0 hour), and TP2 designates 2 treatments at 0 hour and at 48 hours. The assay readout was performed at 72 hours. (C) STAT3 siRNA–mediated induction of apoptotic cell death as determined in 2A cells by expression of cleaved caspase 3 (left panel) and annexin V binding (right panel).