{"id":"9d1b92e6-c312-5579-9850-a6ad05be818b","stable_key":"2921131d-0ba0-51d3-8f59-8c4be3b9ac08:cucurbitacin-b-gpx4-expression","predicate":"reduces_tested_expression_of","statement":"Cucurbitacin B exposure decreased GPX4 protein expression in the human nasopharyngeal-cancer experiments.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"7f0d3edb-22ae-545e-b24c-ba83c4ef1f5d","mechanism_event_label":"A lipid-peroxide defense protein decreased in this model.","subject":{"id":"a544a561-7647-55f6-8ba1-c7ab0133f968","slug":"cucurbitacin-b","display_name":"Cucurbitacin B","entity_type_key":"small_molecule"},"object":{"id":"e9bb13ee-f238-51e6-9101-78ddfd11465c","slug":"gpx4","display_name":"GPX4","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"7f0d3edb-22ae-545e-b24c-ba83c4ef1f5d","stable_key":"2921131d-0ba0-51d3-8f59-8c4be3b9ac08:cucurbitacin-b-gpx4-expression-event","event_type":"observed_relationship","label":"A lipid-peroxide defense protein decreased in this model.","description":"Cucurbitacin B exposure decreased GPX4 protein expression in the human nasopharyngeal-cancer experiments.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"a544a561-7647-55f6-8ba1-c7ab0133f968","slug":"cucurbitacin-b","display_name":"Cucurbitacin B","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"e9bb13ee-f238-51e6-9101-78ddfd11465c","slug":"gpx4","display_name":"GPX4","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"b44c9e27-4bbb-52d3-a022-14cddded5073","slug":"glutathione","display_name":"GSH","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"cec3de0d-ba4c-55ab-863c-1b16e4c38e61","slug":"human-cucurbitacin-lipid-peroxidation","display_name":"Human cancer-cell lipid peroxidation during cucurbitacin B exposure","entity_type_key":"cellular_process"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human nasopharyngeal-cancer cells; animal tumor work also reported.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Expression is not direct GPX4 binding or evidence of selenium depletion.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Cucurbitacins collection; species, compartment, exposure, co-substrates and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"cucurbitacin","display_name":"Cucurbitacins","entity_type_key":"chemical_species"}},{"dimension":"plain_language","value_text":"A lipid-peroxide defense protein decreased in this model.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Induction of ferroptosis in human nasopharyngeal cancer cells by cucurbitacin B: molecular mechanism and therapeutic potential. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33664249/ · DOI 10.1038/s41419-021-03516-y","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"10ac53fd-538e-5931-8bb4-5e52f1d03e19","evidence_kind":"source_excerpt","locator":"Lines 244-250","start_line":244,"end_line":250,"excerpt":"## cucurbitacin-b-gpx4-expression\nA lipid-peroxide defense protein decreased in this model.\nCucurbitacin B exposure decreased GPX4 protein expression in the human nasopharyngeal-cancer experiments.\nModel: Human nasopharyngeal-cancer cells; animal tumor work also reported.\nLimitations: Expression is not direct GPX4 binding or evidence of selenium depletion.\nEvidence access: Primary abstract\nInduction of ferroptosis in human nasopharyngeal cancer cells by cucurbitacin B: molecular mechanism and therapeutic potential. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33664249/ · DOI 10.1038/s41419-021-03516-y","model_system":"Human nasopharyngeal-cancer cells; animal tumor work also reported.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"77324310-00ce-5d28-9fc7-595fddae86b9","stable_key":"import-2921131d-0ba0-51d3-8f59-8c4be3b9ac08","title":"Cucurbitacins: thiol chemistry, cytoskeleton, metabolic dependencies and signaling (2026-09-20)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. 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