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Diallyl trisulfide (DATS), a garlic organosulfide, has shown excellent chemopreventive potential. Cisplatin (DDP) is widely used to treat solid malignant tumors, but causing serious side effects. In the current study, we attempted to elucidate the chemopreventive mechanisms of DATS in human gastric cancer BGC-823 cells in vitro, and to investigate whether DATS could enhance the anti-tumor efficacy of DDP and improve quality of life in BGC-823 xenograft mice in vivo. Treatment with DATS (25–400 μmol/L) dose-dependently inhibited the viability of BGC-823 cells in vitro with an IC50 of 115.2±4.3 μmol/L after 24 h drug exposure. DATS (50–200 μmol/L) induced cell cycle arrest at G2/M phase in BGC-823 cells, which correlated with significant accumulation of cyclin A2 and B1. DATS also induced BGC-823 cell apoptosis, which was accompanied by the modulation of Bcl-2 family members and caspase cascade activation. In BGC-823 xenograft mice, administration of DATS (20–40 mg·kg−1·d−1, ip) dose-dependently inhibited tumor growth and markedly reduced the number of Ki-67 positive cells in tumors. Interestingly, combined administration of DATS (30 mg·kg−1·d−1, ip) with DDP (5 mg/kg, every 5 d, ip) exhibited enhanced anti-tumor activity with fewer side effects. We showed that treatment of BGC-823 cells with DATS in vitro and in vivo significantly activated kinases such as p38 and JNK/MAPK and attenuated the Nrf2/Akt pathway. This study provides evidence that DATS exerts anticancer effects and enhances the antitumor efficacy of DDP, making it a novel candidate for adjuvant therapy for gastric cancer.

Diallyl trisulfide (DATS), an organosulfuric component of garlic oil, exhibits potential anticancer and chemopreventive effects. Cisplatin (DDP), a common chemotherapeutic agent, has provided great therapeutic contributions to treating solid tumors, but with serious side effects. Here, we verified the anti-tumor properties of DATS on lung cancer in vitro and in vivo, and evaluated synergistic effects of DATS combined with DDP on the NCI-H460 xenograft model. Significantly decreased cell viabilities, cell cycle G1 arrest, and apoptosis induction were observed in DATS treated NCI-H460 cells (p

The 70 kD heat shock proteins (Hsp70s) are ubiquitous and highly conserved molecular chaperones essential for cellular protein folding and proteostasis. Each Hsp70 has two functional domains: a nucleotide-binding domain (NBD) that binds and hydrolyzes ATP, and a substrate-binding domain (SBD) that binds extended polypeptides. NBD and SBD interact little when in ADP; however, ATP binding allosterically couples the polypeptide- and ATP-binding sites. ATP binding promotes polypeptide release; polypeptide rebinding stimulates ATP hydrolysis. This allosteric coupling was poorly understood. To explore the molecular mechanism of this essential ATP-induced allosteric coupling, we solved a crystal structure of an intact Hsp70 from E. coli in complex with ATP at 1.96 A resolution. NBD-ATP adopts a unique conformation, forming extensive interfaces with a radically changed SBD that has its α-helical lid displaced and the polypeptide-binding pocket of its β-subdomain flipped open. Our biochemical analysis inspired by this structure provides a long-sought mechanistic explanation of how ATP binding allosterically opens the polypeptide-binding site.

Direct estimation of the number of channels on a membrane path is important for channel biophysics. It is a classical question and has been addressed elegantly by previous studies. Especially, pioneering researchers took the advantage of fluctuations in membrane conductance caused by ion channels opening and closing. The number of channels, the single-channel current, and the probability of the channel opening can be obtained using the method of non-stationary or stationary fluctuation analysis. Here, we developed a method to count the number of channels by simultaneous electrical recording of channel opening and optical recording of the fluorescence from the green fluorescent protein(GFP) tagged to the channel. Based on the number of channels and the macroscopic current, we first tuned this method using the cyclic-nucleotide gated (CNG) channel, of which the single channel conductance and open probability are well characterized. Then we applied the I-F relationship to the hyperpolarization-activated, cAMP-regulated HCN channel, of which the estimation of single channel conductance has been controversial. We estimated that the number of channels on a piece of membrane patch could read 10,000 to 20,000 and the single channel conductance for mHCN2 channel is about 1.82 pico Siemens.