Abstract: 【Abstract】 Objective To evaluate the effect of chidamide combined with matrine on proliferation and apoptosis of cutaneous T-cell lymphoma （CTCL） cell lines HH and Hut78, and to explore their apoptotic mechanisms. Methods Both HH and Hut78 cells were treated with 0.4 μmol/L chidamide and 0.6 g/L matrine alone or in combination for 24, 48 and 72 hours, with those treated with dimethyl sulfoxide （DMSO） serving as control groups. MTS assay was performed to detect cellular proliferation rates of HH and Hut78 cells at each time point. After 48-hour treatment, flow cytometry was conducted to detect cell apoptosis, and Western blot analysis to determine expression of apoptosis-related proteins in these cells. Statistical analysis was carried out by using repeated measures analysis of variance, one-way analysis of variance, and least significant difference （LSD）-t test for multiple comparisons. Results Compared with DMSO, chidamide and matrine alone or in combination could inhibit the proliferation of HH and Hut78 cells to different extents （F = 15.88, 558.26, P < 0.05, < 0.001, respectively）. At 48 hours, the apoptosis rate in Hut78 cells was significantly higher in the matrine group （20.98% ± 1.53%）, chidamide group （22.44% ± 7.74%） and combination group （44.53% ± 1.85%） than in the control group （8.42% ± 4.23%; LSD-t = 4.76, 5.31, 13.69 respectively, all P < 0.05）, as well as in the combination group than in the matrine group and chidamide group （LSD-t = 8.93, 8.37 respectively, both P < 0.01）; no significant differences were observed in the apoptosis rate of HH cells between the matrine group （13.98% ± 3.86%） or chidamide group （13.61% ± 1.62%） and control group （11.44% ± 1.43%, both P > 0.05）, while the combination group （20.94% ± 0.64%） showed a significantly higher apoptosis rate compared with the control group, matrine group and chidamide group （LSD-t = 7.37, 5.40, 5.69 respectively, all P < 0.05）. In the case of HH cells, the combination group showed significantly higher cleaved caspase-3 expression （all P < 0.05）, but significantly lower protein expression of E-cadherin, nuclear factor （NF）-κB, phosphorylated-Bad （p-Bad） and Bcl-2 compared with the other 3 groups （all P < 0.05）. In the case of Hut78 cells, the expression of E-cadherin, NF-κB, p-Bad and Bcl-2 was significantly lower in the matrine group, chidamide group and combination group than in the control group （all P < 0.05）, while cleaved caspase-3 expression was significantly higher in the chidamide group and combination group than in the control group （both P < 0.05）. No matter in HH cells or in Hut78 cells, there were no significant differences in Bad protein expression between the 4 groups （all P > 0.05）. Conclusion Chidamide in combination with matrine can inhibit proliferation and induce apoptosis of HH and Hut78 cells, likely by regulating the expression of apoptosis-related proteins E-cadherin, NF-κB, p-Bad, Bcl-2 and cleaved caspase-3.

Key words: Lymphoma, T-cell, cutaneous, Matrine, Apoptosis, Chidamide, Hut78 cells, HH cells