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Rationale: Myoepithelial carcinoma mainly occurs in the salivary glands, but myoepithelial carcinoma of the lung is extremely rare neoplasm whose biological behavior and clinical course still remain to be fully elucidated. Although considered as low-grade carcinoma, these tumors have a high rate of recurrence or distant metastasis., Patient Concerns: To date there are only 11 cases of pulmonary myoepithelial carcinoma reported in the English literature. We report a case of a 24-year-old woman diagnosed with primary pulmonary myoepithelial carcinoma. Informed consent was obtained from the patient., Diagnoses: The tumor derived from superior lobe of left lung and exhibited only myoepithelial differentiation without any ductal formation by histopathological and immunohistochemical analysis., Interventions: The patient underwent the left superior lobe resection. In addition, we first introduce second-generation sequencing technology as a novel strategy for primary pulmonary myoepithelial carcinoma, and these tumors should be included in the differential diagnosis of thoracic neoplasms., Outcomes: The patient was alive with no evidence of disease for up to 12 months., Lessons: Individualized treatment is the promising clinical strategy for thoracic neoplasms, and the underlying molecular events should be investigated to find the potential therapeutic targets.

Background: Carboetomidate is a pyrrole etomidate analog that is 3 orders of magnitude less potent an inhibitor of in vitro cortisol synthesis than etomidate (an imidazole) and does not inhibit in vivo steroid production. Although carboetomidate's reduced functional effect on steroid synthesis is thought to reflect lower binding affinity to 11β-hydroxylase, differential binding to this enzyme has never been experimentally demonstrated. In the current study, we tested the hypothesis that carboetomidate and etomidate bind with differential affinity to 11β-hydroxylase by comparing their abilities to inhibit photoaffinity labeling of purified enzyme by a photoactivatable etomidate analog and to modify the enzyme's absorption spectrum in a way that is indicative of ligand binding. In addition, we made a preliminary exploration of the manner in which etomidate and carboetomidate might differentially interact with this site using spectroscopic methods as well as molecular modeling techniques to better understand the structural basis for their selectivity., Methods: The ability of azi-etomidate to inhibit cortisol synthesis was tested by assessing its ability to inhibit cortisol synthesis by H295R cells. The binding affinities of etomidate and carboetomidate to 11β-hydroxylase were compared by assessing their abilities to (1) inhibit photoincorporation of the photolabile etomidate analog [(3)H]azi-etomidate into the enzyme and (2) modify the absorption spectrum of the enzyme's heme group. In silico docking studies of etomidate, carboetomidate, and azi-etomidate binding to 11β-hydroxylase were performed using the computer software GOLD., Results: Similar to etomidate, azi-etomidate potently inhibits in vitro cortisol synthesis. Etomidate inhibited [(3)H]azi-etomidate photolabeling of 11β-hydroxylase in a concentration-dependent manner. At a concentration of 40 µM, etomidate reduced photoincorporation of [(3)H]azi-etomidate by 96% ± 1% whereas carboetomidate had no experimentally detectable effect. On addition of etomidate to 11β-hydroxylase, a type 2 difference spectrum was produced indicative of etomidate complexation with the enzyme's heme iron; carboetomidate had no effect whereas azi-etomidate produced a reverse type 1 spectrum. Computer modeling studies predicted that etomidate, carboetomidate, and azi-etomidate can fit into the heme-containing pocket that forms 11β-hydroxylase's active site and pose with their carbonyl oxygens interacting with the heme iron and their phenyl rings stacking with phenylalanine-80. However, additional unique poses were identified for etomidate and azi-etomidate that likely account for their higher affinities., Conclusions: Carboetomidate's reduced ability to suppress in vitro and in vivo steroid synthesis as compared with etomidate reflects its lower binding affinity to 11β-hydroxylase and may be attributed to carboetomidate's inability to form a coordination bond with the heme iron located at the enzyme's active site.