Evolution of ceftazidime-avibactam resistance driven by mutations in double-copy blaKPC-2 to blaKPC-189 during treatment of ST11 carbapenem-resistant Klebsiella pneumoniae.

Klebsiella pneumoniae carbapenemase (KPC) variants can contribute to resistance to ceftazidime-avibactam (CZA) in Klebsiella pneumoniae (KP). However, two-copy KPC variant-mediated resistance to CZA has rarely been reported to date. Here, we aimed to clarify the evolutionary trajectory of CZA resistance driven by mutations in double-copy blaKPC-2 to blaKPC-189 carried by the tandem core structure (ISKpn6-blaKPC-ISKpn27-tnpR-IS26) during treatment of ST11 carbapenem-resistant K. pneumoniae (CRKP). The CZA-resistant KP strain carried double-copy blaKPC-189, a variant with alanine-threonine and aspartate-tyrosine substitutions at Ambler amino acid positions 172 (A172T) and 179 (D179Y) of blaKPC-2. Clone experiments confirmed that, compared with that of the wild-type blaKPC-2 clone strain, the minimum inhibitory concentration of CZA increased 16-fold in the blaKPC-189-mutant strain. Furthermore, protein structure analysis revealed the A172T and D179Y mutations of blaKPC-189 can have a direct effect on the binding affinity of CAZ and AVI for KPC. Sequence comparison revealed that blaKPC-189 was mutated in a double-copy format upon CZA exposure, which was carried by the IS26-mediated tandem core structure ISKpn27-blaKPC-ISKpn6. This tandem core structure apparently evolves in vivo during infection, although not by self-transferring, and multiple ISKpn27-blaKPC-ISKpn6 copy numbers could mediate transferable CZA resistance upon mobilization. In addition, compared with the wild-type blaKPC-2 gene, the blaKPC-189 gene had no fitness cost. In summary, our study highlighted the emergence of CZA-resistant blaKPC-189 variants in the ST11 clone and the presence of a double-copy blaKPC-189 in the IncFII-type plasmid, which is carried by a tandem core structure (IS26-ISKpn6-blaKPC-189-ISKpn27-tnpR-IS26). IMPORTANCE: To date, ceftazidime-avibactam (CZA) resistance caused by double-copy Klebsiella pneumoniae carbapenemase (KPC) variants has not been elucidated. The multicopy forms of carbapenem resistance genes carried by the same plasmid are relatively rare in most carbapenem-resistant Enterobacteriaceae. In this study, we elucidate the evolutionary trajectory of CZA resistance in ST11 carbapenem-resistant K. pneumoniae harboring a double-copy blaKPC and provide new insights into the mechanisms of acquired resistance to CZA.

Dimeric-(-)-epigallocatechin-3-gallate inhibits the proliferation of lung cancer cells by inhibiting the EGFR signaling pathway.

Non-small cell lung cancer (NSCLC) is one of the most general malignant tumors. The overexpression of epidermal growth factor receptor (EGFR) is a common marker in NSCLC, and it plays an important role in the proliferation, invasion, and metastasis of cancer cells. At present, drugs developed with EGFR as a target suffer from drug resistance, so it is necessary to study new compounds for the treatment of NSCLC. The active substance in green tea is EGCG, which has anti-cancer effects. In this study, we synthesized dimeric-(-)-epigallocatechin-3-gallate (prodelphinidin B-4-3,3‴-di-O-gallate, PBOG), and explored the effect of PBOG on lung cancer cells. PBOG can inhibit the proliferation and migration of NCI-H1975 cells, promote cell apoptosis, and inhibit cell cycle progression. In addition, PBOG can bind to the EGFR ectodomain protein and change the secondary structure of the protein. At the same time, PBOG decreases the expression of EGFR and downstream protein phosphorylation. Animal experiments confirmed that PBOG can inhibit tumor growth by inhibiting EGFR phosphorylation. Collectively, our study results show that PBOG may induce a decrease in intracellular phosphorylated EGFR expression by binding to the EGFR ectodomain protein, thereby inducing apoptosis and inhibiting cell cycle progression, thus providing a new strategy to treat lung cancer.

Synthesis and in vitro biological evaluation of novel dendrocandin analogue as potential anti-tumor agent.

Dendrocandins are characteristic chemical structures of D. officinale and have strong physiological bioactivities. In this study, a dendrocandin analogue (1) has been prepared by total synthesis (9 steps, 12.6% overall yield) in which coupling reaction and Wittig reaction as the key steps. Compound 1 was also evaluated for its anticancer activity in vitro against six human cancer cells (MCF-7, A549, A431, SW480, HepG-2 and HL-60) using MTT assays. Compound 1 showed potent cytotoxicity, with the IC50 value 16.27 ± 0.26 µM. The expression levels of apoptotic proteins indicated that compound 1 can up-regulate the expression of apoptotic proteins, leading to apoptosis. This compound suggested that it's potential as anticancer agent for further development.

Novel Perbutyrylated Glucose Derivatives of (-)-Epigallocatechin-3-Gallate Inhibit Cancer Cells Proliferation by Decreasing Phosphorylation of the EGFR: Synthesis, Cytotoxicity, and Molecular Docking.

Lung cancer is one of the most commonly occurring cancer mortality worldwide. The epidermal growth factor receptor (EGFR) plays an important role in cellular functions and has become the new promising target. Natural products and their derivatives with various structures, unique biological activities, and specific selectivity have served as lead compounds for EGFR. D-glucose and EGCG were used as starting materials. A series of glucoside derivatives of EGCG (7-12) were synthesized and evaluated for their in vitro anticancer activity against five human cancer cell lines, including HL-60, SMMC-7721, A-549, MCF-7, and SW480. In addition, we investigated the structure-activity relationship and physicochemical property-activity relationship of EGCG derivatives. Compounds 11 and 12 showed better growth inhibition than others in four cancer cell lines (HL-60, SMMC-7721, A-549, and MCF), with IC50 values in the range of 22.90-37.87 µM. Compounds 11 and 12 decreased phosphorylation of EGFR and downstream signaling protein, which also have more hydrophobic interactions than EGCG by docking study. The most active compounds 11 and 12, both having perbutyrylated glucose residue, we found that perbutyrylation of the glucose residue leads to increased cytotoxic activity and suggested that their potential as anticancer agents for further development.

Demethyleneberberine promotes apoptosis and suppresses TGF-ß/Smads induced EMT in the colon cancer cells HCT-116.

Colorectal cancer (CRC) is one of the most common malignant tumours in the world. Recent reports have revealed natural products displayed inhibition on colon cancer potential by suppressing transforming growth factor-ß/Smads induced epidermal-mesenchymal transition (EMT). In this article, 12 kinds of natural berberine analogues were screened for their effects on the inhibition of the colon cancer cells, the results showed that demethyleneberberine (DM-BBR) exhibited an interesting and potential effect on inducing the apoptosis of HCT-116 cells with drug concentrations of 6, 12 and 18 µM. Particularly, DM-BBR reversed the EMT process by inhibiting the expression of p-Smad2 and p-Smad3 in the transforming growth factor-ß/Smads signal pathway, up-regulated pro-apoptotic protein cleaved caspase-9, and blocked cell cycle at the S phase and increasing the expression of cyclin proteins P27 and P21. Taken together, these findings suggested that DM-BBR could promote apoptosis and suppress TGF-ß/Smads induced EMT in the colon cancer cells HCT-116.