| Background:In recent years there has been a growing harmful red tides outbreak in China and othercountries. Harmful red tides had caused damage to the stability of marine ecosystems andseriously red tide toxins have already threatened fisheries and human health. OA is known as onemajor component of diarrhetic shellfish poisoning, the toxins responsible for the humanintoxication. It is a hydrophobic fatty acid polyether and targets mainly the gastrointestinal tractin acute poisoning, causing diarrhea and vomit by enrichment of the food chain or consumptiondirectly produced by marine dinoflagellates. Previous studies demonstrated that okadaic acidinduces apoptosis and carcinogenesis in different cell lines. It has already confirmed that okadaicacid treat can induce human hepatocellular cell line, colonic epithelial cell line andneuroblastoma cell line ect cancer cell lines apoptosis. Currently most reports were about OA’stoxicity testing using by some cell lines and to guide prevention and control of red tide.Due to this, our study was then interesting to know whether OA can induce A549cells apoptosis,a human lung adenocarcinoma cell line and non-target organ tumor cell line of okadaic acid. Thetarget of this study is to find out the multiplication change of A549cells when incubated withOA. Then analysis of ultra microscope structure change and cytomorphology observations toascertain the facts whether okadaic acid has inhibitory effect on A549cell multiplication anddiscussing the real cause of this inhibitory effect, then providing theoretical basis in cellular leveland seeking new drugs for the treatment of lung adenocarcinoma.Methods:1. MTT assay and trypan blue exclusion test (TBET) were used to measure the effect on A549cell multiplication.2. Giemsa staining method, immunohistochemical experiment, H33258staining test, acridineorange (AO) fluorescence staining assay and inverted phase contrast microscope were used toobserve the change of cytomorphology.3. Ultra microscope structure change was observed by transmission electron microscope.4. Flow cytometry was adopted to examine cell cycle.5. The change of Caspase was measured through spectrophotometry.Results:1. The results of cell survival evaluated by TBET and colorimetric assay with3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide (MTT) showed: The number ofA549cells was in a dose-dependent decreased, OA significant inhibitory effect on A549cellmultiplication. 2. Cytomorphology observation of okadaic acid-treated cells show that cells became shrinkageand turned round, some cells were floated in the nutrient medium, nucleus agglutination broken,resulting in apoptotic bodies, significant apoptosis phenomenon was discovered.3. Transmission electron microscope observed that the microvillus of A549disappeared,characteristic vacuolation was appeared, karyopyknosis and forming a crescent cap structuredistributed throughout the karyoplasms, significant apoptotic bodies were surround the cells.4. OA can block A549cell cycle in G0/G1phase and inhibit A549cell multiplication.5. The apoptosis may duo to the activation of Caspase-8result in Caspase-3got it’s activation,ultimately cells were dying.Nowadays, lung cancer is a kind of disease that is threaten to human health and livesseriously, and the majority of cancer patients who were dead are suffering from lung cancer. Themorbidity and mortality rates of lung cancer are improved remarkably in the world.The resultsclearly demonstrate that OA has significant inhibitory effect on A549cell multiplication andcells had a high sensitivity to OA; Apoptosis is the mainly cause of this effect, then it can avoidinflammatory reaction. This research was preliminary proved that OA has the potential to be anew treatment of human lung adenocarcinoma.
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