Individual or combined treatment with demethylation agent and HDAC inhibitors is a possible therapeutic strategy for cHL. (A) 5-aza-2′-deoxycytidine and/or trichostatin A (TSA) induced PU.1 expression in cHL cell lines. Treatment of L540, HDLM2, HD-70, and KM-H2 cells with 1μM 5-aza-2′-deoxycytidine induced PU.1 expression after 3 days. In contrast, treatment of L428 cells with 1μM 5-aza-2′-deoxycytidine failed to induce PU.1 expression, whereas the combined treatment with 1μM 5-aza-2′-deoxycytidine and 500nM TSA led to induction of PU.1 expression after 3 days. (B-E) Treatment of L540 (B), HD-70 (C), HDLM2 (D), and KM-H2 (E) cells with 1μM 5-aza-2′-deoxycytidine induced growth arrest. (F) Treatment of L428 cells with 1μM 5-aza-2′-deoxycytidine failed to induce growth arrest. (G) The combined treatment of L428 cells with 1μM 5-aza-2′-deoxycytidine and 500nM of TSA induced growth arrest.