PD0325901 also dose dependently inhibited the growth of TAMH cells in vitro (Fig. 1A). Inhibition of MEK activity and cell growth were also observed in PD0325901-treated HepG2 and Hep3B human HCC cells in vitro, thus demonstrating MEK-dependent growth (Figs. 1B, C). Furthermore, apoptosis was dose dependently induced in HepG2 and Hep3B cells in vitro after treatment with PD0325901 for 48 hours (Fig. 1D). The higher dose of PD0325901 required to induce apoptosis in Hep3B cells correlates with the greater sensitivity of HepG2 cells to PD0325901 compared with Hep3B cells. http://www.selleckchem.com/products/Adriamycin.html Athymic mice bearing TAMH flank tumors were given the MEK inhibitor

PD0325901 (20 mg/kg) or HPMT vehicle daily by orogastric gavage. After a one-time 24-hour treatment, ex vivo tissue analysis was performed, and P-ERK levels were determined by immunoblot (Fig. 2A). After 24 hours of treatment, intratumoral P-ERK levels decreased Selleck GSK2126458 in animals receiving a single dose of PD0325901 compared with those animals receiving vehicle. Serial volumetric measurements of the athymic mouse TAMH flank tumors treated for 16 days were obtained. The growth rate of these tumors was expressed as the percentage increase in tumor size from the start of treatment (Fig. 2B). After 16 days of treatment, the growth rate of the flank tumors in the PD0325901 treatment

arm (n = 9) was reduced threefold compared with the vehicle-treated arm (n = 8) (1113% ± 269% versus 3077 ± 483%, P < 0.01). This demonstrates that PD0325901 can effectively reduce TAMH tumor growth in vivo. Similarly, PD0325901 (10 mg/kg) significantly inhibited human HCC tumor growth over a 4-week period in the Hep3B xenograft model (Fig. 3). No drug-induced toxicity

indicated by weight loss or treatment related mortality was observed in either of these studies. MT42 (CD-1) TGF-α transgenic mice were injected with diethylnitrosamine (5 mg/kg) at 14 days of age. At 30 weeks of age, TGF-α transgenic mice were treated with either PD0325901 (20 mg/kg) or vehicle by daily orogastric gavage for 35 days. No evidence of weight loss was observed in either group. On sacrifice, cAMP the animals underwent necropsy, and gross tumor incidence was noted. Whereas vehicle-treated animals had a 47.1% (8 of 17 total) incidence of HCC, animals treated with the MEK inhibitor PD0325901 demonstrated a significant decrease in HCC incidence, down to 13.3% (2 of 15 total; P < 0.05). This represents an approximately 3.5-fold decrease in gross tumor incidence. Because what percentage of transgenic mice had tumors at the start of the prior randomized trial was unknown, a second study was initiated in which the mice were screened by MRI to identify tumor-bearing animals (Fig. 4). Once tumors were noted on MRI (week 0), a follow-up MRI was performed 2 weeks later (week 2) to determine baseline growth of the index lesions.