TMZ(Temozolomide)

Methazolastone causes formation of DNA alkali-labile sites which are present in similar amounts and repaired at a similar rate in L-1210 and L-1210/BCNU cell lines. In L-1210 but not in L-1210/BCNU methazolastone induces an arrest of cells in SL-G2-M phases.^[1] Methazolastone sensitivity of both chemo-sensitive and resistant cells (D54-R and U87-R) is enhanced significantly under hyperoxia. Both Methazolastone and hyperoxia are associated with increased phosphorylation of ERK p44/42 MAPK (Erk1/2), but to a lesser extent in D54-R cells, suggesting that Erk1/2 activity may be involved in regulation of hyperoxia and Methazolastone-mediated cell death. Hyperoxia enhances Methazolastone toxicity in GBM cells by induction of apoptosis, possibly via MAPK-related pathways. ^[2] Methazolastone induces in monocytes the DNA damage response pathways ATM-Chk2 and ATR-Chk1 resulting in p53 activation. ^[3] Chronic Methazolastone exposure results in acquired Methazolastone-resistance and elevates miR-21 expression. ^[4] Methazolastone treatment triggers endoplasmic reticula (ER) stress with increased expression of GADD153 and GRP78 proteins, and deceases pro-caspase 12 protein. Methazolastone induces autophagy through mitochondrial damage- and ER stress-dependent mechanisms to protect glioma cells. ^[5]

After a daily i.p. dose of 40 mg/kg for 5 consecutive days (days 1-5 after tumor transplant), methazolastone increases life-span by 86% in L-1210 and 22% in L-1210/BCNU. In L-1210/BCNU no effect is seen after 100 μM or 200 μM treatment; only 400 μM methazolastone produced an accumulation of cells in premitotic phase but much less than in L-1210. In L-1210/BCNU the maximum accumulation of cells in SL-G2-M is, after 48 hours-72 hours, approximately 30% as compared to 23% in untreated cells. Cells accumulates in SL-G2-M occurred too when L- 1210 leukemia-bearing mice are treated i.v. with methazola stone (40 mg/kg). No such effect is seen on L-1210/BCNU cells from mice given the same drug dose. ^[1]

• Cell lines

  L-1210 and L-1210/BCNU cells

• Concentrations

  0 μM -100 μM

• Incubation Time

  l hours

• Method

  L-1210 and L-1210/BCNU cells are seeded at 0.2 × 10₄ cells/mL and incubated for 24 hours. The cultures are treated with Methazolastone for l hours at 37oC, then washed twice in PBS by centrifugation and resuspended in fresh medium. Controls and treated samples are diluted in fresh medium 1:4 at 48 hours and 1:2 at 96 hours. Using these dilutions cell concentrations throughout the experiments are between 3 × 10₅ and 8 × 10₅/mL. Control growth is logarithmic in this range.

• Animal Models

  DBA/2 mice with L-1210 and L-1210/BCNU cells

• Dosages

  40 mg/kg

• Administration

  Administered via i.v.