protoapigenone and Neoplasms

DNA damage caused during cancer treatment can rapidly activate the ataxia telangiectasia-mutated (ATM) and ATM and Rad3-related (ATR)-dependent phosphorylation of Chk2 and Chk1 kinases, which are hallmarks of the DNA damage response (DDR). Pharmacologic inhibition of ATR causes a synthetic lethal effect on ATM- or p53-defective cancers, suggesting that such inhibition is an effective way to improve the sensitivity of cancers to DNA-damaging agents. Here, both the natural compound protoapigenone (WYC02) and its synthetic derivative WYC0209 exhibited cytotoxic effects on various cancer cell lines. WYC02 causes chromosomal aberration in the mitotic spreads of Chinese hamster ovary cells. Interestingly, cancer cells did not exhibit typical DDR markers upon exposure to WYC02 and WYC0209 (WYCs). Further investigation into the molecular mechanisms of WYCs function revealed that they have a potential ability to inhibit DDR, particularly on activation of Chk1 and Fanconi anemia group D2 protein (FANCD2), but not Chk2. In this way, WYCs inhibited ATR-mediated DNA damage checkpoint and repair. Furthermore, when combined with the DNA cross-linking agent cisplatin, treatment with WYCs resulted in increased tumor sensitivity to interstrand cross-link-generating agents both in vitro and in vivo. Our results therefore especially implicate WYCs in enhancing tumor chemosensitivity when the ATR checkpoint is constitutively active in states of oncogene-driven replicative stress or tolerance to DNA-interfering agents.

Topics: Animals; Ataxia Telangiectasia Mutated Proteins; Cell Cycle Proteins; Cell Line, Tumor; Checkpoint Kinase 1; Chromosome Aberrations; Cricetinae; Cyclohexanones; DNA Damage; DNA Repair; Drug Resistance, Neoplasm; Female; Flavones; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasms; Phosphorylation; Protein Kinases; Protein Serine-Threonine Kinases; Signal Transduction

The synthesis of a new compound 9 containing the 4-hydroxy-2,5-cyclohexadien-1-one system, a key elements toward elucidation of the protoapigenone 1 antitumor pharmacophore, was described. The compound showed potent in vitro antitumor potency with low micromolar IC(50)'s against breast, ovarian, prostate, liver, pancreas, and blood cancer cell lines tested and could inhibit tumor growth in vivo but no significant impairment of hematopoiesis or immune function was observed. The minimum structural pharmacophore of 1 has now been refined.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Cyclohexanones; Female; Flavones; Humans; Inhibitory Concentration 50; Male; Neoplasms

The aim of this study was to evaluate the antitumor potential of Macrothelypteris torresiana by studying in vitro antitumor activity of the protoapigenone, as well as in vivo antitumor activity and acute/subacute oral toxicity of the total flavonoid fraction from the roots of M. torresiana. Considering that the protoapigenone is a main constituent of the total flavonoid fraction and it might play a key role in the antitumor activity of M. torresiana, the MTT assay was used to investigate the in vitro antitumor activity of the protoapigenone. Our study revealed that the protoapigenone of M. torresiana showed significant antitumor activity towards Hep G2, Tca-8113, MCF-7, M5 and K562 with IC(50) values of 2.3, 0.6, 0.8, 0.3 and 0.9 μg/ml, respectively. The antitumor potential of the total flavonoid fraction was evaluated using preparations 1, 2 and 3, which were prepared by total flavonoid fraction directly diluted with sterile saline, dissolved using sodium carboxymethyl cellulose (CMC-Na) and included by hydroxypropyl-β-cyclodextrin, respectively. These were investigated in vivo using mouse sarcoma S-180 in BALB/c mice after completing tumor inoculation for 24h. Pronounced antitumor activity was observed in the treated groups for preparations 2 and 3, and the high and medium doses in particular showed very high inhibition ratio of tumor growth (>50%). No significant difference was observed when compared to the positive control group (5-fluorouracil). The acute/subacute oral toxicity test was performed, and the results of acute oral toxicity showed that the LD(50) values of preparations 2 and 3 were 2.76 and 0.87 g/kg body wt., respectively. According to the results of the subacute oral toxicity study, the total flavonoid fraction had low toxicity. The overall results of this study suggest that the total flavonoid fraction from the roots of M. torresiana shows significant antitumor activity and represents a potential source of medicine for the treatment of cancer.

Topics: Animals; Antineoplastic Agents, Phytogenic; Cell Line, Tumor; Cyclohexanones; Female; Ferns; Flavones; Hep G2 Cells; Humans; Male; Mice; Mice, Inbred BALB C; Neoplasms; Phytotherapy; Plant Components, Aerial; Plant Extracts; Plant Roots; Sarcoma; Xenograft Model Antitumor Assays