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Numerous studies have documented that various naturally derived ligands or synthetic non-thiazolidinediones (TZD) as peroxisome proliferator-activated receptor gamma (PPARgamma) agonists have shown moderate or potent antitumor activities, which is PPARgamma independent or partially dependent. However, the PPARgamma agonistic or glucose-lowering activity is ranked first more often than antitumor activity to determine promising novel PPARgamma agonists for potential clinical use. In this study, we hypothesized that there might exist some compounds with less PPARgamma agonistic activity but potent antitumor activity. Thereafter, we evaluated the PPARgamma agonistic and antitumor activity of a novel series of alpha-aryloxy-alpha-methylhydrocinnamic acid derivatives synthesized with the initial aim of developing novel PPARgamma agonists as hypoglycemic agents. MTT assay results revealed that several compounds were able to inhibit cell proliferation in a dose-dependent manner with IC(50) 12.7-29.7 microM, better than that of rosiglitazone (45.9-141 microM), although the PPARgamma agonistic activity of most compounds is much lower than rosiglitazone. Some compounds induced cell cycle arrest and apoptosis tested by Flow Cytometry. Oral administration of DH9 (100 mg/kg/d) for 21 days to BALB/c nude mice bearing xenografts including MGC-803, NCI-H460, HT-29 and OS-RC-2 cells significantly retarded tumor growth. DG8 and DJ5 showed benefits in some of the above four xenografts. Our findings demonstrate that these compounds have potent antitumor activity in vitro and in vivo and pyrimidinyl-arylpropionic acid derivatives might be viable resources in the development of new antineoplastic agents.

Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists have shown benefit in treating diabetes mellitus, atherosclerosis and cancer. However, widespread use of thiazolidinediones (TZDs), the clinically used synthetic PPARgamma agonists, has been limited by adverse cardiovascular effects. Consequently, numerous novel non-TZD compounds were synthesized and antidiabetic efficacy was evaluated to identify PPARgamma agonists for potential clinical use. On the other hand, many studies have documented that the antitumor activity of PPARgamma agonists is PPARgamma independent. Here we hypothesized that there might exist some compounds with less PPARgamma agonistic activity or antidiabetic efficacy but potent antitumor activity. In this study, we evaluated the PPARgamma agonistic and antitumor activity of several newly synthesized alpha-aryloxy-alpha-methylhydrocinnamic acid derivatives as PPARgamma agonists in a panel of human cancer cell lines, which showed promising antitumor activity without appreciable PPARgamma agonistic activity. The results of MTT assay revealed that cell viability was inhibited in a dose dependent manner with IC(50) 17.1-55.1 microM for all the novel compounds and rosiglitazone (17.2-165 microM). They induced cell cycle arrest and apoptosis tested by Flow Cytometry. In conclusion, our findings demonstrate that these compounds have potent in vitro cytotoxicity, the possible mechanism of which is through induction of apoptosis and cell cycle arrest.

Background: Due to chemotherapy resistance in osteosarcoma subgroups, the prognosis of these patients is still poor, and the development of new agents is of utmost importance. The aim of our study was to test the antitumor effects of two novel alpha-aryloxy-alpha-methylhydrocinnamic acid derivatives as peroxisome proliferator-activated receptor (PPAR) gamma agonists, together with rosiglitazone, a well-known thiazolidinedione (TZD) acting on several osteosarcoma cell lines., Methods/results: The MTT assay revealed that cell viability was inhibited in a dose-dependent manner with IC(50) 6.2-15.8 microM for the two novel compounds and rosiglitazone (48.4-83.5 microM). Exposure to DG8 and DH9 at low micromolar concentrations induced a dose-dependent block of DNA synthesis and colony formation. In these antitumor assays, DG8 and DH9 were more effective than rosiglitazone, although the PPARgamma agonistic activity of rosiglitazone is much higher. The SiRNA approach to downregulate specifically PPARgamma in U-2OS cells did not affect the cytotoxic efficiency of either the two novel compounds or rosiglitazone., Conclusion: These observations suggest that non-TZDs with less PPARgamma agonistic activity might show more potent antitumor efficacy independent of PPARgamma in human osteosarcoma cells, which supports the possibility that they could be beneficial in the treatment of osteosarcoma patients., (Copyright 2009 S. Karger AG, Basel.)