3-MA (3-Methyladenine)

The slight preference for Vps34 prevention by 3-Methyladenine probably arises from a hydrophobic ring specific to Vps34, which encircles the 3-methyl group of 3-Methyladenine. ^[1] 3-Methyladenine has been reported to cause cancer cell death under both normal and starvation conditions. 3-Methyladenine could also suppress cell migration and invasion independently of its ability to inhibit autophagy, implying that 3-Methyladenine possesses functions other than autophagy suppression. 3-Methyladenine elicits caspase-dependent cell death that is independent of autophagy inhibition. Treatment with 5 mM 3-Methyladenine reduces the percentage of glucose-starved HeLa cells displaying GFP-LC3 puncta to 23%. The levels of LC3-I are increasing and the levels of LC3-II are decreasing between 12 and 48 hours in cells that are treated with 3-Methyladenine. Conversion of LC3-I to LC3-II is suppressed by 3-Methyladenine. Treatment of HeLa cells with 3-Methyladenine at 2.5 mM or 5 mM for one day does not affect cell viability, whereas treatment with 10 mM 3-Methyladenine for one day causes a 25.0% decrease in cell viability. Treatment of cells with 2.5, 5 or 10 mM 3-Methyladenine for two days causes 11.5%, 38.0% and 79.4% decrease in viability, respectively. 3-Methyladenine decreases cell viability in a time- and dose-dependent manner. 3-Methyladenine significantly shortens the duration of nocodazole-induced-prometaphase arrest. ^[2] Suppression of autophagy by 3-Methyladenine inhibits SU11274-induced cell death. ^[3] Prolonged treatment with 3-Methyladenine (up to 9 hours) induces significant LC3 I to II conversion in wild type MEFs. Prolonged treatment with 3-Methyladenine, but not wortmannin, markedly increases GFP-LC3 punctuation/aggregation. 3-Methyladenine-induced LC3 conversion and free GFP liberation are ATG7-dependent. 3-Methyladenine treatment leads to evident increase of p62 protein level. 3-Methyladenine increases the p62 level even in Atg5−/− MEFs as well as in cells with DOX-mediated deletion of ATG5. 3-Methyladenine inhibits class I and class III PI3K in different temporal patterns. 3-Methyladenine-induced LC3 I to LC3 II conversion is dramatically compromised in Tsc2−/− cells compared with wild type cells.3-Methyladenine disrupts the anti-autophagic function of mTOR complex 1. ^[4]

Cell (such as HeLa cell) viability is determined by a trypan blue exclusion assay. Briefly, after treated with 3-Methyladenine, both adherent and floating cells are collected and suspended in phosphate buffered saline (PBS, pH 7.4) at a final density of 1-2 × 10⁶/mL. An equal volume of 0.4% trypan blue solution (w/v, in PBS) is added to the cell suspension and mixed thoroughly. After incubation at room temperature for 3 min, cell counting is performed using a hemacytometer.

3-Methyladenine blocks autophagy through its effect on class III phosphatidylinositol 3-kinase (PI3K). 3-Methyladenine treatment does not alter the degree of hemorrhage compared with the subarachnoid hemorrhage (SAH) group. 3-Methyladenine pretreatment significantly aggravates neurological symptoms when compared with the SAH + vehicle group. Autophagy is decreased when 3-Methyladenine treatment is applied. Conversely, cleaved caspase-3 is markedly up-regulated in the SAH + 3-Methyladenine group. In line with the up-regulation of cleaved caspase-3 expression, the number of TUNEL-positive cells in the right cortex is significantly increased in the SAH + 3-Methyladenine group compared with the SAH + vehicle group. ^[5]