Degradation of MCL-1 by bufalin reverses acquired resistance to osimertinib in EGFR-mutant lung cancer.

Although osimertinib, an EGFR tyrosine kinase inhibitor, has become the standard therapy for treating non-small cell lung cancer (NSCLC) patients with EGFR-activating mutation, upregulation of MCL-1 induces acquired resistance to osimertinib. Bufalin, a natural digoxin-like ingredient isolated from a traditional Chinese medicine Chan Su, has been shown to downregulate MCL-1 in NSCLC cells. However, whether bufalin reverses this acquired resistance to osimertinib in NSCLC cells remains unclear. In this study, bufalin reduced cell viability and promoted apoptosis in osimertinib-resistant cells. Moreover, co-treatment with bufalin and osimertinib restored the sensitivity of osimertinib-resistant cells to osimertinib-induced growth regression and apoptosis in vitro and in vivo. Mechanistically, MEK/ERK-dependent MCL-1 phosphorylation and Ku70-mediated MCL-1 overexpression confer osimertinib resistance in EGFR-mutant NSCLC cells. In osimertinib-resistant cells, bufalin modulates Ku70-mediated MCL-1 degradation, but not MEK/ERK/MCL-1 signaling. In conclusion, our study suggests that bufalin eliminates resistance to osimertinib by inhibiting Ku70-mediated MCL-1 overexpression, indicating that a combination of osimertinib and bufalin could be an effective additional treatment to overcome acquired resistance to osimertinib in NSCLC cells.

[Effect of bufalin combined gefitinib on lung cancer H1975 cells and its mechanisms research].

OBJECTIVE: To observe the effect of bufalin combined Gefitinib on lung cancer H1975 cells, and to explore its potential mechanisms for anti-tumor. METHODS: The cytostatic effects of bufalin (1 -100 nmol/L), gefitinib (0.1-20 micromol/L), and bufalin plus gefitinib on H1975 cells were evaluated by MTT assay. Their effects on apoptosis of H1975 cells were determined by flow cytometry (FCM). Their effects on expressions of epidermal growth factor receptor (EGFR) and Met signal pathway related proteins in H1975 cells were detected by Western blot. RESULTS: Results of MTT assay showed that gefitinib over 5 micromol/L could inhibit H1975 cells. But combined therapy of bufalin and gefitinib could potently inhibit the growth of H1975 cells. Results of FCM showed the apoptotic rate was 61.64% +/- 5.61% in the bufalin plus gefitinib group, obviously higher than that of the bufalin group (18.34% +/- 3.42%) and the gefitinib group (7.32% +/- 1.08%), showing statistical difference (P < 0.01). Results of Western blot showed the protein expressions of p-EGFR, p-Met, p-Akt, and p-mTOR in H1975 cells could be markedly down-regulated by bufalin plus gefitinib. CONCLUSIONS: Combination of bufalin and gefitinib potently inhibited the growth of H1975 cells, and induced cell apoptosis. The potential mechanism for anti-tumor might be involved in blocking EGFR-PI3k/Akt pathway.

Bufalin Reverses HGF-Induced Resistance to EGFR-TKIs in EGFR Mutant Lung Cancer Cells via Blockage of Met/PI3k/Akt Pathway and Induction of Apoptosis.

The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib and erlotinib, have shown promising therapeutic efficacy in nonsmall cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor- (EGFR-) activating mutation. However, the inevitable recurrence resulting from acquired resistance has limited the clinical improvement in therapy outcomes. Many studies demonstrate that hepatocyte growth factor- (HGF-) Met axis plays an important role in tumor progression and drug sensitivity. HGF may induce resistance to EGFR-TKIs in EGFR mutant lung cancer cells by Met/PI3K/Akt signaling. The purpose of this study was to determine whether bufalin, a major bioactive component of Venenum Bufonis, could reverse HGF-induced resistance to reversible and irreversible EGFR-TKIs in mutant lung cancer cells PC-9, HCC827, and H1975. Our studies showed that bufalin could reverse resistance to reversible and irreversible EGFR-TKIs induced by exogenous HGF in EGFR mutant lung cancer cells by inhibiting the Met/PI3K/Akt pathway and inducing death signaling. These results suggested that bufalin might have a potential to overcome HGF-induced resistance to molecular-targeted drugs for lung cancer.

The chemical composition of human milk from Inner Mongolia of China.

In Inner Mongolia, China, the chemical composition of 66 breast milk samples at three lactation stages was analysed. Except for total nitrogen content, the contents of total solid, fat, NPN, lactose and ash were not significantly different between colostral, transitional and mature milk. Fatty acids did not vary over the three lactation stages, while unsaturated fatty acids accounted for 59.95-63.22% of the total fatty acids. Relatively low contents of vitamins were in the milk because the volunteer mothers did not take any vitamin supplementation over the entire lactation period. Besides sodium and phosphate, the concentrations of most minerals in the breast milk remained fairly constant across the three lactation stages.