D-meth accelerates replicative senescence.

<p>(A-D) Effects of D-meth (1 mM, closed bars) or vehicle (open bars) on (A) senescence-associated -galactosidase (-Gal) staining, (B) cell morphology, (C) ceramide levels, and (D) expression of CerS5 mRNA in primary MEF cultures. (E-F) Effects of D-meth on replicative capacity assessed by (E) [³H]-thymidine incorporation into DNA and (F) number of cumulative population doublings (vehicle: open squares, D-meth: closed squares). (g-j) Effects of D-meth (M, 1 mM), L-cycloserine (L-CS, 30 μM) and combination of D-meth plus L-CS on transcription of senescence-associated markers: (G) p53, (H) p21, (I) IL-6 and (J) TNF-α. (K, L) Effects of L-CS (30 μM), fumonisin B₁ (FB1, 50 μM) and cell-permeant C8 ceramide (10 μM) on -Gal expression elicited by D-meth (M, 1 mM). ANOVA followed by Bonferroni <i>post hoc</i> test: *<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.001, <i>vs</i>. vehicle; ^<i>$</i><i>P</i><0.05, ^<i>$$$</i><i>P</i><0.001, <i>vs</i> vehicle at passage 1. ^<i>##</i><i>P</i><0.01, <i>vs</i> D-meth.