CD40 activation induces VEGF transcripts in human MM cells expressing mutant p53.

(A) CD40-activated RPMI 8226 (upper panel) and SV (lower panel) MM lines were cultured for indicated intervals (0-48 hours), and total RNA (5 μg) was subjected to Northern blotting using human VEGF cDNA, as described in Figure 1. After probing for VEGF mRNA, the blot was stripped and hybridized with an 18S rRNA probe. The fold induction relative to 18S rRNA as a control was calculated by densitometry. Both cell lines express mt p53 at 37°C (restrictive temperature) and wt p53 at 28°C (permissive temperature). (B) Total RNA (5 μg) from patient MM cells without (−) or with (+) CD40 activation (24 hours) at 37°C was subjected to Northern blotting for VEGF expression. Fold induction of VEGF relative to an 18S rRNA probe was calculated by densitometry.