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Dynamic foldamers are synthetic folded molecules which can change their conformation in response to an external stimulus and are currently at the forefront of foldamer chemistry. However, constitutionally dynamic foldamers, which can change not only their conformation but also their molecular constitution in response to their environment, are without precedent. We now report a size- and shape-switching small dynamic covalent foldamer network which responds to changes in pH. Specifically, acidic conditions direct the oligomerization of a dipeptide-based building block into a 16-subunit macrocycle with well-defined conformation and with high selectivity. At higher pH the same building block yields another cyclic foldamer with a smaller ring size (9mer). The two foldamers readily and repeatedly interconvert upon adjustment of the pH of the solution. We have previously shown that addition of a template can direct oligomerization of the same building block to yet other rings sizes (including a 12mer and a 13mer, accompanied by a minor amount of 14mer). This brings the total number of discrete foldamers that can be accessed from a single building block to five. For a single building block system to exhibit such highly diverse structure space is unique and sets this system of foldamers apart from proteins. Furthermore, the emergence of constitutional dynamicity opens up new avenues to foldamers with adaptive behavior.

Using small molecules to inhibit the PD-1/PD-L1 pathway is an important approach in cancer immunotherapy. Natural compounds such as capsaicin, zucapsaicin, 6-gingerol and curcumin have been proposed to have anticancer immunologic functions by downregulating the PD-L1 expression. PD-L1 dimerization promoted by small molecules was recently reported to be a potential mechanism to inhibit the PD-1/PD-L1 pathway. To clarify the molecular mechanism of such compounds on PD-L1 dimerization, molecular docking and molecular dynamics simulations were performed. The results evidenced that these compounds could inhibit PD-1/PD-L1 interactions by directly targeting PD-L1 dimerization. Binding free energy calculations showed that capsaicin, zucapsaicin, 6-gingerol and curcumin have strong binding ability with the PD-L1 dimer, where the affinities of them follow the trend of zucapsaicin > capsaicin > 6-gingerol ≈ curcumin. Analysis by residue energy decomposition, contact numbers and nonbonded interactions revealed that these compounds have a tight interaction with the C-sheet, F-sheet and G-sheet fragments of the PD-L1 dimer, which were also involved in the interactions with PD-1. Moreover, non-polar interactions between these compounds and the key residues Ile54, Tyr56, Met115 and Ala121 play a key role in stabilizing the protein–ligand complexes in solution, in which the 4′-hydroxy-3′-methoxyphenyl group and the carbonyl group of zucapsaicin, capsaicin, 6-ginger and curcumin were significant for the complexation of small molecules with the PD-L1 dimer. The conformational variations of these complexes were further analyzed by free energy landscape (FEL) and principal component analysis (PCA) and showed that these small molecules could make the structure of dimers more stable. This work provides a mechanism insight for food-derived small molecules blocking the PD-1/PD-L1 pathway via directly targeting the PD-L1 dimerization and offers theoretical guidance to discover more effective small molecular drugs in cancer immunotherapy.

Recovery of noble metals and

Protein ubiquitination is one of the most common yet complex post-translational modifications in eukaryotes that plays an important role in various biological processes including cell signal transduction, growth, and metabolism. Disorders in the ubiquitination process have been revealed to correlate with the occurrence and development of many diseases such as neurodegenerative disease, inflammation, and cancer. Investigation of protein ubiquitination is of great importance to uncover protein functions, understand the molecular mechanisms underlying biological processes, and develop novel strategies for disease treatment. Great advances have been made toward understanding protein ubiquitination; however, it remains a challenging task due to the high diversity of ubiquitination sites and structures, as well as the dynamic nature of ubiquitination in biological processes. Protein ubiquitination occurs through the formation of a covalent bond between the carboxyl terminus of ubiquitin and the e-amino group of a lysine residue in the substrate. As a small protein, ubiquitin itself can be further modified by another ubiquitin molecule to form homotypic or heterotypic polyubiquitin chains. There are eight sites, namely seven lysine residues (K6, K11, K27, K29, K33, K48, and K63) and one N-terminal methionine (M1), in one ubiquitin molecule that can be used to form a ubiquitin dimer. The variations in modification sites, ubiquitin chain lengths, and conformations result in differences in protein sorting, cell signaling, and function. To resolve the high complexity of protein ubiquitination, new separation approaches are required. Affinity separation based on the specific recognition between biomolecules offers high selectivity and has been employed to study the structures and functions of ubiquitination. In addition, affinity ligands are central to the separation performance. Different affinity ligands have been developed and employed for the capture and enrichment of ubiquitylated proteins. Immunoaffinity separation based on antigen-antibody interactions has been one of the most classical separation methods. Antibodies against ubiquitin or different ubiquitin linkages have been developed and widely applied for the enrichment of ubiquitylated proteins or peptides. The specific capture allows the downstream identification of endogenous ubiquitination sites via mass spectrometry and thus facilitates understanding of the roles and dynamics of polyubiquitin signals. Ubiquitin-binding domains (UBDs) are a collection of modular protein domains that can interact with ubiquitin or polyubiquitin chains. Ubiquitin-associated domains, ubiquitin-interacting motifs, and ubiquitin-binding zinc finger domains are the most frequently used UBDs. Due to the moderate affinity of UBDs toward ubiquitin or ubiquitin chains, tandem ubiquitin-binding entities (TUBEs) have been engineered with high affinities (Kd in the nanomolar range) and exhibit potential as powerful tools for ubiquitination analysis. Because of their affinity and selectivity, UBDs and TUBEs have been applied for the isolation and identification of ubiquitylated targets in cancer cells and yeasts. Compared with antibodies and UBDs, peptides are smaller in size and can be facilely synthesized via chemical approaches. The modular structure of peptides allows for de novo design and screening of artificial ubiquitin affinity ligands for targeted capture of ubiquitinated proteins. Furthermore, the polyhistidine tag at the N-terminus of ubiquitin facilitates the purification of ubiquitylated substrates using immobilized metal affinity chromatography. Considering the high complexity of biosystems, strategies combining multiple affinity ligands have emerged to further improve separation efficiency and reduce background interference. Several combinations of antibodies with UBDs, antibodies with peptidyl tags, and UBDs with peptidyl tags have been developed and proven to be effective for the analysis of protein ubiquitination. These affinity-based approaches serve as important solutions for studying the structure-activity relationship of protein ubiquitination. This review highlights the applications and recent advances in affinity separation techniques for analyzing protein ubiquitination, focusing on the methods using antibodies, UBDs, peptides, and their combinations as affinity ligands. Further, their applications in the enrichment of ubiquitin-modified substrates and the identification of ubiquitination structures are introduced. Additionally, remaining challenges in affinity separation of protein ubiquitination and perspectives are discussed.

The development of hydrazone bond-oriented epitope imprinting strategy is reported to synthesize the polymeric binders for the selective recognition of a protein-β

Apoptosis plays an essential role in a multicellular organism's lifecycle. Developing technologies for selectively monitoring apoptotic processes can be useful not only in the evaluation of disease progression, but also in the assessment of their therapeutic intervention. However, quantitative imaging of cell apoptosis is still a challenge. In this work, we reported a cell-permeable peptide probe with a ratiometric fluorescence response specifically toward caspase-3, a key enzyme for the execution of apoptosis. This probe Ac-Tat-DEVD-CV consisted of a caspase-3 recognition sequence Asp-Glu-Val-Asp (DEVD), a cell-penetrating peptide Tat (RKKRRORRR), and a long wavelength fluorophore, cresyl violet (CV). Upon selective hydrolyzation by caspase-3, the probe released CV and displayed a ratiometric change in fluorescence. Facilitated by the cell-penetrating peptide, this probe can easily internalize into cells. The ratiometric response property bestowed the probe with advantages in the real-time quantification of caspase-3 activity, thus estimating the apoptotic stages in living cells. This method could offer opportunities to evaluate apoptosis-related disease progression and therapeutic monitoring.

Incorporation of earth-abundant Cu is one of the most important approaches to improve the practicability of TiO2 for photoreduction of CO2 into value-added solar fuels. However, the molecular insight on the role of Cu is complicated and far from understood. We performed a first principle calculation on the anatase (101) surface modified by a single Cu atom deposited on the surface (CuS) or doped in the lattice (CuL). It is demonstrated the CuL is clearly more stable than the CuS and could promote the formation of oxygen vacancy (Vo) greatly. The CuS plays a role of donor, while the CuL is electronically deficient and becomes a global electron trapper. If a Vo is introduced, the excess electrons would immigrate to the empty gap state of the CuL and make it half-filled in some case, which implies its metallic characters and improved conductivity; meanwhile, the formation of Ti3+ is suppressed. Judging from the adsorption energies, it is the Vo that primarily improves the adsorption of CO2 in both linear and bent states, and the CuS could hardly stabilize CO2 more, while the promotion effect of Vo could even be counteracted by the CuL due to its electronic deficiency. The reduction pathways (CO2* → CO* + O*) show that, with the assistance of the CuS, linear CO2 could directly transform into the carbonate-like geometry vertically binding to the surface, and the intermediate configuration of the bent CO2 horizontally bridging the Vo could be successfully skipped. Therefore, the barrier of the rate-determining transformation could be lowered from 0.75 to 0.39 eV. Furthermore, it is found the strong adsorption of the produced CO by the CuS might retard the smooth going of the catalytic process.

Tuning autophagy in a controlled manner could facilitate cancer therapy but it remains challenging. Pyridinium-substituted tetraphenylethylene salts (PTPE 1-3), able to target mitochondria and disrupt autophagy after forming complexes with albumin, are reported. Mitochondrion affinity and autophagy-inducing activity are improved by prolonging the length of alkyl chains in PTPE 1-3. PTPE 1-3 demonstrate proautophagic activity and a mitophagy blockage effect. Failure of autophagosome-lysosome fusion in downstream autophagy flux results in cancer cell death. Moreover, fast formation of complexes of PTPE 1-3 with albumin in blood can facilitate biomimetic delivery and deep tumor penetration. Efficient tumor accumulation and effective tumor suppression are successfully demonstrated with in vitro and in vivo studies. PTPE 1-3 salts exhibit dual functionality: they target and image mitochondria because of aggregation-induced emission effects and they are promising for cancer therapy.

Nanomedicine with stable light-heat conversion and spatiotemporally controllable drug activation is crucial for the success of photothermal therapy (PTT). Herein, a metal-organic framework (MOF)-based nanoheater with light-triggered multi-responsiveness is engineered to in-situ and on-demand sensitize cancer cells to local hyperthermia. Well-dispersed platinum nanoparticles synthesized inside nanospaces of the MOF are employed as the near-infrared (NIR)-harvesting unit with stable and high light-heat conversion performance. A conformation switchable polymer shell is constructed as a secondary light-responding unit to gate the targeted activation of a molecular inhibitor against thermoresistance. By cascade transformation of light stimuli to downstream signals, the nanoheater enables inhibitor release to go with local heating at the same time restricted in lesion sites to maximize efficacy and minimize systemic toxicity. The efficient photothermal conversion and the blockage of cellular heat-protective pathways provide a dual-mode of action which selectively sensitizes cancer cells to hyperthermia in a spatiotemporally controlled manner. With NIR as the remote switch, the MOF-based nanosystem demonstrates localized and boosted PTT efficacy against cancer both in vitro and in vivo. These results present nanosized MOFs as tailorable and versatile platforms for synergistic and precise cancer therapy.

Inhibitors blocking the PD-1/PD-L1 immune checkpoint demonstrate impressive anti-tumor immunity, and small molecule inhibitors disclosed by the Bristol-Myers Squibb (BMS) company have become a hot topic. In this work, by modifying the carbonyl group of BMS-202 into a hydroxyl group to achieve two enantiomers (MS and MR) with a chiral center, we found that this is an effective way to regulate its hydrophobicity and thus to reduce the negative effect of polar solvation free energy, which enhances the stability of PD-L1 dimer/inhibitor complexes. Moreover, we studied the binding modes of BMS-200 and BMS-202-related small molecule inhibitors by molecular dynamics simulation to explore their inhibitory mechanism targeting PD-L1 dimerization. The results showed that the size exclusion effect of the inhibitors triggered the rearrangement of the residue ATyr56, leading to the formation of an axisymmetric tunnel-shaped pocket, which is an important structural basis for improving the binding affinity of symmetric inhibitors with PD-L1. Furthermore, after inhibitor dissociation, the conformation of ATyr123 and BMet115 rearranged, which blocked the entrance of the binding pocket, while the reverse rearrangements of the same residues occurred when the PD-L1 monomer was complexed with the inhibitors, preparing PD-L1 for dimerization. Overall, this study casts a new light on the inhibitory mechanism of BMS inhibitors targeting PD-L1 dimerization and provides an idea for designing novel small molecule inhibitors for future cancer immunotherapy.

In cancer immunotherapy, an emerging approach is to block the interactions of programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) using small-molecule inhibitors. The food-derived polyphenols curcumin (CC), resveratrol (RSV) and epigallocatechin gallate (EGCG) have anticancer immunologic functions, which, recently, have been proposed to act via the downregulation of PD-L1 expression. However, it remains unclear whether they can directly target PD-L1 dimerization and, thus, interrupt the PD-1/PD-L1 pathway. To elucidate the molecular mechanism of such compounds on PD-L1 dimerization, molecular docking and nanosecond molecular dynamics simulations were performed. Binding free energy calculations show that the affinities of CC, RSV and EGCG to the PD-L1 dimer follow a trend of CC &gt, RSV &gt, EGCG. Hence, CC is the most effective inhibitor of the PD-1/PD-L1 pathway. Analysis on contact numbers, nonbonded interactions and residue energy decomposition indicate that such compounds mainly interact with the C-, F- and G-sheet fragments of the PD-L1 dimer, which are involved in interactions with PD-1. More importantly, nonpolar interactions between these compounds and the key residues Ile54, Tyr56, Met115, Ala121 and Tyr123 play a dominant role in binding. Free energy landscape and secondary structure analyses further demonstrate that such compounds can stably interact with the binding domain of the PD-L1 dimer. The results provide evidence that CC, RSV and EGCG can inhibit PD-1/PD-L1 interactions by directly targeting PD-L1 dimerization. This provides a novel approach to discovering food-derived small-molecule inhibitors of the PD-1/PD-L1 pathway with potential applications in cancer immunotherapy.

Peptides participate in and regulate many important life processes as neurotransmitters, hormones and receptors. With detailed understanding of the structure and function of peptides, chemically synthesized peptides have shown great value in the fields of biomedicine and life analysis. Human atrial natriuretic peptide (ANP) is a polypeptide hormone consisting of 28 amino acids. The abnormalities in the content and metabolism of ANP are closely related to the diseases like cardiovascular diseases and cancer. In view of the important physiological functions of ANP, herein we monitored and optimized the chemical synthesis of ANP chemical synthesis. The strategy involved integrating solid phase synthesis of linear peptide chain and liquid phase oxidation. Based on the excellent separation performance of HPLC and the excellent qualitative ability of mass spectrometry (MS), a new method based on ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was established to monitor the synthesis reaction and to separate and purify the obtained products. This study provides a reference for the efficient chemical synthesis and oxidative ring formation of human atrial natriuretic peptide.

Recently, we reported the first VOx/SiO2 ethylene polymerization catalyst for making Cl-free UHMWPE, and found the dominant promotion effects of Al-/Ti-/Zr-modifications over this catalyst system (Macromol. Chem. Phys. 2017, 218, 1600443). In this work, density functional theory is applied to investigate the underlying mechanism of this remarkable promotion effect of Al-/Ti-/Zr-modifications on a molecular and atomic level. The cluster model with V(III) is found to be the most possible active site due to its lowest overall energy barrier for monomer insertion, though the process of C2H4 coordination and the subsequent formation of transition state are most energy favored for V(II) species. By modifying one of or both V-O-Si in the active model with V-O-M (M = Al, Ti, or Zr), the energy barrier for the binding of the upcoming C2H4 gets lower (particularly for Al- and Zr-modified catalysts), and the transition state also becomes more stable. Generally, the insertion process of C2H4 gets easier after support Al-/Ti-/Zr-modifications. This dominant promotion effect is partially ascribed to the more enriched positive charge distribution on or nearby the V center, and the narrower energy gap between the LUMO of model catalysts and the HOMO of C2H4 for these modified catalysts also contributes much. In addition, the decreased steric hindrance around the V center should be taken into account for the modified models as well. Furthermore, the Bronsted acidity of the catalysts is investigated by introducing a pendent hydroxyl group to the model catalysts, which has a close contact with the V center. Similar promotion effect of support modification by Al, Ti, and Zr could still be observed.

Multiple myeloma (MM) is a hematopoietic malignancy characterized by the clonal proliferation of antibody-secreting plasma cells. Bortezomib (BZM), the first FDA-approved proteasome inhibitor, has significant antimyeloma activity and prolongs the median survival of MM patients. However, MM remains incurable predominantly due to acquired drug resistance and disease relapse. β-Catenin, a key effector protein in the canonical Wnt signaling pathway, has been implicated in regulating myeloma cell sensitivity to BZM. Decitabine (DAC) is an epigenetic modulating agent that induces tumor suppressor gene reexpression based on its gene-specific DNA hypomethylation. DAC has been implicated in modulating Wnt/β-catenin signaling by promoting the demethylation of the Wnt/β-catenin antagonists sFRP and DKK. In this study, we report the effects of single reagent DAC therapy and DAC combined with BZM on β-catenin accumulation, myeloma cell survival, apoptosis, and treatment sensitivity. Our study proved that DAC demethylated and induced the reexpression of the Wnt antagonists sFRP3 and DKK1. DAC also reduced GSK3β (Ser9) phosphorylation and decreased β-catenin accumulation in the nucleus, which were induced by BZM. Thus, the transcription of cyclin D1, c-Myc, and LEF/TCF was reduced, which synergistically inhibited cell proliferation, enhanced BZM-induced apoptosis, and promoted BZM-induced cell cycle arrest in myeloma cells. In summary, these results indicated that DAC could synergistically enhance myeloma cell sensitivity to BZM at least partly by regulating Wnt/β-catenin signaling. Our results can be used to optimize therapeutic regimens for MM.

A dramatically improved, uniform distribution of commercial ultrahigh molecular weight polyethylene (UHMWPE) with high-density polyethylene (HDPE) via solution blending, rather than that of melt blending, is often apparent in experimental investigation. Recently, we demonstrated that a UHMWPE/HDPE blend created by in-reactor polymerization with a Cr/V bimetallic catalyst supported on modified silica can obtain an even better molecular chain distribution while saving energy and solution costs, even more so than experiments using a solution blend. Furthermore, by gel-spinning processing, an abundance of hierarchical, interlocking shish-kebab crystals were generated in the in-reactor polymerized blend fibers (IRBFs), exhibiting better mechanical properties than those of solution blend fibers (SBFs). The tensile strength of the IRBFs increased by about 20% under the same draw ratio, since the interlocking shish-kebab structures contributed to homogenous deformation. The two kinds of fibers exhibit high crystallinity and have a highly oriented shish-kebab structure. Compared with the SBFs, the IRBFs inclined to form longer shish features and smaller kebab sizes, and the draw process was more conducive to the transformation of kebab to shish structures. Thus, the IRBFs can obtain an excellent hierarchal network structure, benefiting more from the hot-stretching process. Our work lays a solid foundation for the efficient fabrication of high-performance UHMWPE/HDPE fibers as well as the optimization of an original polyethylene catalyst system.

Metal-peptide interactions provide plentiful resource and design principles for developing functional biomaterials and smart sensors. Pb2+, as a borderline metal ion, has versatile coordination modes. The interference from competing metal ions and endogenous chelating species greatly challenges Pb2+ analysis, especially in complicated living biosystems. Herein, a biomimetic peptide-based fluorescent sensor GSSH-2TPE was developed, starting from the structure of a naturally occurring peptide glutathione. Lewis acid-base theory was employed to guide the molecular design and tune the affinity and selectivity of the targeting performance. The integration of peptide recognition and aggregation-induced emission effect provides desirable sensing features, including specific turn-on response to Pb2+ over 18 different metal ions, rapid binding, and signal output, as well as high sensitivity with a detection limit of 1.5 nM. Mechanism investigation demonstrated the balance between the chelating groups, and the molecular configuration of the sensor contributes to the high selectivity toward Pb2+ complexation. The ion-induced supramolecular assembly lights up the bright fluorescence. The ability to image Pb2+ in living cells was exhibited with minimal interference from endogenous biothiols, no background fluorescence, and good biocompatibility. With good cell permeability, GSSH-2TPE can monitor changes in Pb2+ levels and biodistribution and thus predict possible damage pathways. Such metal-peptide interaction-based sensing systems offer tailorable platforms for designing bioanalytical tools and show great potential for studying the cell biology of metal ions in living biosystems.

Bisphenol A (BPA) is a globally utilized industrial chemical and is commonly used as a monomer of polycarbonate plastics and epoxy resins. Recent research reveals that BPA could cause potential adverse biological effects and liver dysfunction. However, the underlying mechanisms of BPA-induced hepatoxicity and gut dysbiosis remain unclear and deserve further study. In this study, male Sprague Dawley rats were exposed to different doses (0, 30, 90, and 270 mg/kg bw) of BPA by gavage for 30 days. The results showed that the high dose of BPA decreased superoxide dismutase (SOD), glutathione (GSH), and increased malondialdehyde (MDA) levels. Moreover, a high dose of BPA caused a significant increase in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C), while high-density lipoprotein cholesterol (HDL-C) was significantly decreased in BPA-treated rats. The gene expression of PGC-1α and Nrf1 were decreased in the liver of high doses of BPA-administrated rats, as well as the protein levels of SIRT1, PGC-1α, Nrf2, and TFAM. However, the protein expression of IL-1β was significantly increased in BPA-treated rats. In addition, BPA weakened the mitochondrial function of hepatocytes and promoted cell apoptosis in the liver by up-regulating the protein levels of Bax, cleaved-Caspase3, and cleaved-PARP1 while down-regulating the Bcl-2 in the liver. More importantly, a high dose of BPA caused a dramatic change in microbiota structure, as characterized at the genus level by increasing the ratio of Firmicutes to Bacteroidetes (F/B), and the relative abundance of Proteobacteria in feces, while decreasing the relative abundance of Prevotella_9 and Ruminococcaceae_UCG-014, which is positively correlated with the content of short-chain fatty acids (SCFAs). In summary, our data indicated that BPA exposure caused hepatoxicity through apoptosis and the SIRT1/PGC-1α pathway. BPA-induced intestinal flora and SCFA changes may be associated with hepatic damage. The results of this study provide a new sight for the understanding of BPA-induced hepatoxicity.

Programmed cell death-1 (PD-1), which is a molecule involved in the inhibitory signal in the immune system and is important due to blocking of the interactions between PD-1 and programmed cell death ligand-1 (PD-L1), has emerged as a promising immunotherapy for treating cancer. In this work, molecular dynamics simulations were performed on complex systems consisting of the PD-L1 dimer with (S)-BMS-200, (R)-BMS-200 and (MOD)-BMS-200 (i.e., S, R and MOD systems) to systematically evaluate the inhibitory mechanism of BMS-200-related small-molecule inhibitors in detail. Among them, (MOD)-BMS-200 was modified from the original (S)-BMS-200 by replacing the hydroxyl group with a carbonyl to remove its chirality. Binding free energy analysis indicates that BMS-200-related inhibitors can promote the dimerization of PD-L1. Meanwhile, no significant differences were observed between the S and MOD systems, though the R system exhibited a slightly higher energy. Residue energy decomposition, nonbonded interaction, and contact number analyses show that the inhibitors mainly bind with the C, F and G regions of the PD-L1 dimer, while nonpolar interactions of key residues Ile54, Tyr56, Met115, Ala121 and Tyr123 on both PD-L1 monomers are the dominant binding-related stability factors. Furthermore, compared with (S)-BMS-200, (R)-BMS-200 is more likely to form hydrogen bonds with charged residues. Finally, free energy landscape and protein–protein interaction analyses show that the key residues of the PD-L1 dimer undergo remarkable conformational changes induced by (S)-BMS-200, which boosts its intimate interactions. This systematic investigation provides a comprehensive molecular insight into the ligand recognition process, which will benefit the design of new small-molecule inhibitors targeting PD-L1 for use in anticancer therapy.

Yushuang Luo, Pengjie Yu, Junhui Zhao, Qijing Guo, Baohua Fan, Yinzhuo Diao, Yulong Jin, Jing Wu, Chengwu Zhang Department of Oncology, Affiliated Hospital of Qinghai University, Xining 810001, People’s Republic of ChinaCorrespondence: Chengwu ZhangDepartment of Oncology, Affiliated Hospital of Qinghai University, Xining 810001, People’s Republic of ChinaEmail cwzhang19@163.comBackground: Gastric cancer (GC) is one of the most common malignant tumors and the second most frequent cause of cancer death worldwide. Crocin is a kind of bioactive constituent found in the stigmas of saffron, which has shown various pharmacological activities.Methods: In this study, we investigated the inhibitory effect of crocin on gastric cancer AGS cells proliferation and explored the underlying mechanism. A series of methods were used including cell counting kit assay, gene microarray analysis, qRT-PCR, Celigo image cytometry, cell clone formation assay, Western blot, and cell xenograft growth in vivo.Results: The results indicated that crocin inhibited AGS cells proliferation and promoted cell apoptosis. Further studies suggested that crocin decreased a series of genes expression, among which TPM4 gene downregulation inhibited the tumor cells proliferation and tumor growth in mice, and overexpression of TPM4 gene abolishes the inhibitory effect of crocin. Further study using microarray analysis suggested that knocking down of TPM4 altered genes related to the proliferation and apoptosis of cells.Discussion: Crocin could inhibit the gastric cancer cells AGS cells proliferation by regulating TPM4 gene expression, and TPM4 may be a promising therapeutic target for GC treatment.Keywords: gastric cancer, crocin, TPM4, HER2