OBJECTIVETo investigate changes in the adherent ability, the expression of adhesion related proteins Pyk2 and paxillin during HL-60 cells differentiation into granulocyte-monocyte induced by low-dose (LD) bufalin in combination with all-trans retinoic acid (ATRA), and to explore the effects of bortezomib on cellular adhesion and the expression of Pyk2 and paxillin.

METHODSThe expression of CD11b was detected by flow cytometry, cellular adherence ability by MTT assay, and the expressions of Pyk2, paxillin and tubulin by Western blot.

RESULTSThe combination of 5 nmol/L bufalin and 30 nmol/L ATRA induced HL-60 cells differentiation in a time-dependent manner, the percentages of CD11b positive cells treated for 2 d and 4 d being (20.0 +/- 2.8)% and (75.0 +/- 5.3)%, respectively, with the increasing of cellular adherence ability. Meanwhile the expressions of Pyk2 and Paxillin were also up-regulated in a time-dependent manner. Bortezomib suppressed HL-60 cell adhesion in a dose-dependent manner. At concentrations of 1 nmol/L and 10 nmol/L the adherence level were (7.8 +/- 0.1)% and (5.3 +/- 0.3)%, respectively, with down-regulation of Pyk2 but not Paxillin.

CONCLUSIONPyk2 is involved in the regulation of cellular adherence function. Bortezomib might inhibit HL-60 cells adhension function by down-regulation of Pyk2 expression.