Expression of MTAP inhibits tumor-related phenotypes in HT1080 cells via a mechanism unrelated to its enzymatic function.
Bottom Line: Treatment of MTAP-expressing cells with a potent inhibitor of MTAP's enzymatic activity (MT-DADMe-ImmA) did not result in a MTAP- phenotype.To confirm this, we introduced a catalytically inactive version of MTAP, D220A, into HT1080 cells and found that this mutant was fully capable of reversing the soft agar colony formation, migration, and matrix metalloproteinase phenotypes.Our results show that MTAP affects cellular phenotypes in HT1080 cells in a manner that is independent of its known enzymatic activity.
Affiliation: Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.Show MeSH
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Mentions: HT1080 cells are an immortalized human fibrosarcoma cell line that lacks MTAP expression (Tang et al. 2000). We created MTAP+ (M+) and MTAP− (M−) HT1080 cell lines by stably transfecting either a MTAP expression plasmid or an empty vector control and pooled multiple clones together to minimize the effects of integration events (Tang et al. 2012). The amount of MTAP protein and activity in M+ cells were slightly reduced from those observed in Hela cells (Figure 1, A and B.; compare lane M+ with Hela), indicating that MTAP is being expressed in these cells at near physiologic levels. (We will discuss lanes labeled M+I and D220A in the last two sections.)
Affiliation: Cancer Biology Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.