Essential oil of lemon myrtle (Backhousia citriodora) induces S-phase cell cycle arrest and apoptosis in HepG2 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Lemon myrtle (Backhousia citriodora F.Muell.) leaves, whether fresh or dried, are used traditionally in folk medicine to treat wounds, cancers, skin infections, and other infectious conditions. However, the targets and mechanisms related to anti-cancer effect of lemon myrtle are unavailable. In our study, we found that the essential oil of lemon myrtle (LMEO) showed anti-cancer activity in vitro, and we initially explored its mechanism of action. MATERIALS AND METHODS: We analyzed the chemical compositions of LMEO by GC-MS. We tested the cytotoxicity of LMEO on various cancer cell lines using the MTT assay. Network pharmacology was used also to analyze the targets of LMEO. Moreover, the mechanisms of LMEO were investigated through scratch assay, flow cytometry analysis, and western blot in the HepG2 liver cancer cell line. RESULTS: LMEO showed cytotoxicity on various cancer cell lines with values of IC50 40.90 ± 2.23 (liver cancer HepG2 cell line), 58.60 ± 6.76 (human neuroblastoma SH-SY5Y cell line), 68.91 ± 4.62 (human colon cancer HT-29 cell line) and 57.57 ± 7.61 µg/mL (human non-small cell lung cancer A549 cell line), respectively. The major cytotoxic chemical constituent in LMEO was identified as citrals, which accounted for 74.9% of the content. Network pharmacological analysis suggested that apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1), androgen receptor (AR), cyclin-dependent kinases 1 (CDK1), nuclear factor erythroid 2-related factor 2 (Nrf-2), fatty acid synthase (FASN), epithelial growth factor receptor (EGFR), estrogen receptor 1 (ERα) and cyclin-dependent kinases 4 (CDK4) are potential cytotoxic targets of LMEO. These targets are closely related to cell migration, cycle and apoptosis. Notley, the p53 protein had the highest confidence to co-associate with the eight common targets, which was further confirmed by scratch assay, flow cytometry analysis, and western blot in the HepG2 liver cancer cell line. LMEO significantly inhibited the migration of HepG2 cells in time-dependent and dose-dependent manner. Moreover, LMEO caused a S-phase blocking on HepG2 cells and promoted apoptosis in the meanwhile. Western blot results indicated that p53 protein, Cyclin A2 and Bax proteins were up-regulated, while Cyclin E1 and Bcl-2 proteins were down-regulated. CONCLUSION: LMEO showed cytotoxicity in various cancer cell lines in vitro. Pharmacological networks showed LMEO to have multi-component and multi-targeting effects that are related to inhibit migration of HepG2 cells, and affect cell cycle S-phase arrest and apoptosis through modulation of p53 protein.

Disseminated cutaneous lymphoid hyperplasia of 12 years' duration triggered by vaccination.

Vaccine-induced cutaneous lymphoid hyperplasia (CLH) is rare. Its natural evolution is not well known, nor is its treatment. We report a case of B-cell CLH with secondary dissemination that occurred following vaccination. The symptoms lasted 12 years and were efficiently treated by thalidomide. A 17-year-old girl presented CLH which had begun at the age of 8 at the site of hepatitis B vaccination. The lesions progressively enlarged and disseminated far from the injection sites. There was no spontaneous remission. Cyclins and hydroxychloroquine were inefficient. Thalidomide treatment finally led to complete remission. Aluminium hydroxide is used as adjuvant in the majority of vaccinations. In this case, occurrence of lesions far from the injection site of the vaccine suggested that it was not the only cause and that CLH may occur in other localizations after a vaccination. Furthermore, the diagnosis of CLH should not be excluded in front of such a prolonged course, and we underline the potential efficacy of thalidomide.