You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

TNFα and Fas/FasL pathways are involved in 9-Methoxycamptothecin-induced apoptosis in cancer cells with oxidative stress and G2/M cell cycle arrest. 9-Methoxycamptothecin (MCPT) has been recently reported to have a strong anticancer activity. However, its detailed mechanism of action in human cancer cells has not been well clarified. The results showed that MCPT induced cytotoxicity in seven human cancer cell lines in a dose dependent manner after 72h, with A2780 and Hela cell lines more sensitive, so the two cell lines were chosen to do further studies. MCPT induced strong G2/M arrest in both A2780 cells and Hela cells after 24h, following by substantial sub-G1 arrest (indicating apoptosis). The apoptosis was verified by staining with Annexin V-FITC and propidium iodide. ROS generation increased significantly in MCPT-induced apoptosis. Meanwhile, the apoptosis appeared to be dependent on caspase-3, -8 and -9 in A2780 cells, and caspase-3 in Hela cells. In addition, MCPT induced up-regulation expression of most of seventeen genes in both cell lines. Western blot verified that changes of TNFα, Fas, P53 and P27 protein level were consistent with their gene expression changes. Taken together, MCPT plays an important role in tumor growth suppression by inducing apoptosis in both cell lines via extrinsic and intrinsic apoptotic pathways, and has the potential to be developed into an antitumor agent.
{"Chemical": ["propidium iodide", "9-Methoxycamptothecin", "MCPT", "FITC"]}