Microtubules are dynamic assemblies of ab-tubulin heterodimers and have been recognized as highly attractive targets for cancer chemotherapy. A broad range of agents bind to tubulin and interfere with microtubule assembly. Despite having a long history of characterization, colchicine binding site inhibitors (CBSIs) have not yet reached the commercial phase as anti-cancer drugs to date. We determined the structures of tubulin complexed with a set of structurally diverse CBSIs (lexibulin, nocodazole, plinabulin and tivantinib), among which nocodazole and tivantinib are both binary-function inhibitors targeting cancer-related kinases and microtubules simultaneously. High resolution structures revealed the detailed interactions between these ligands and tubulin. Our results showed that the binding modes of the CBSIs were different from previous docking models, highlighting the importance of crystal structure information in structurebased drug design. A real structure-based pharmacophore was proposed to rationalize key common interactions of the CBSIs at the colchicine domain. Our studies provide a solid structural basis for developing new anti-cancer agents for the colchicine binding site. DatabaseThe atomic coordinates and structure factors for tubulin complexed with lexibulin, nocodazole, plinabulin and tivantinib have been deposited in the Protein Data Bank under accession codes 5CA0, 5CA1, 5C8Y and 5CB4, respectively.

PurposeGastric cancer is a common tumor of the digestive system. Identification of potential molecules associated with gastric cancer progression and validation of potential biomarkers for gastric cancer diagnosis are very important. Thus, the aim of our study was to determine the serum metabolic characteristics of the serum of patients with chronic gastritis (CG) or gastric cancer (GC) and validate candidate biomarkers for disease diagnosis.Experimental DesignA total of 123 human serum samples from patients with CG or GC were collected for untargeted metabolomic analysis via UHPLC-Q-TOF/MS to determine characteristics of the serum. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and heat map were used for multivariate analysis. In addition, commercial databases were used to identify the pathways of metabolites. Differential metabolites were identified based on a heat map with a t-test threshold (p < 0.05), fold-change threshold (FC > 1.5 or FC < 2/3) and variable importance in the projection (VIP >1). Then, differential metabolites were analyzed by receiver operating characteristic (ROC) curve to determine candidate biomarkers. All samples were analyzed for fasting lipid profiles.ResultsAnalysis of serum metabolomic profiles indicated that most of the altered metabolic pathways in the three groups were associated with lipid metabolism (p < 0.05) and lipids and lipid-like molecules were the predominating metabolites within the top 100 differential metabolites (p < 0.05, FC > 1.5 or FC < 2/3, and VIP >1). Moreover, differential metabolites, including hexadecasphinganine, linoleamide, and N-Hydroxy arachidonoyl amine had high diagnostic performance according to PLS-DA. In addition, fasting lipid profile analysis showed the serum levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (Apo-A1) were decreased concomitant to the progression of the progression of the disease compared with those in the control group (p < 0.05).ConclusionsThus, this study demonstrated that lipid metabolism may influence the development of CG to GC. Hexadecasphinganine, linoleamide, and N-Hydroxy arachidonoyl amine were selected as candidate diagnostic markers for CG and GC.

Antibody–drug conjugates (ADCs) take the advantage of monoclonal antibodies to selectively deliver highly potent cytotoxic drugs to tumor cells, which have become a powerful measure for cancer treatment in recent years. To develop a more effective therapy for human epidermal growth factor receptor 2 (HER2)-positive cancer, we explored a novel ADCs composed of anti-HER2 scFv–HSA fusion antibodies conjugates with a potent cytotoxic drug DM1. The resulting ADCs, T-SA1–DM1 and T-SA2–DM1 (drug-to-antibody ratio in the range of 3.2–3.5) displayed efficient inhibition in the growth of HER2-positive tumor cell lines and the half-maximal inhibitory concentration on SKBR-3 and SKOV3 cells were both at the nanomolar levels in vitro. In HER2-positive human ovarian cancer xenograft models, T-SA1–DM1 and T-SA2–DM1 also showed remarkable antitumor activity. Importantly, three out of six mice exhibited complete remission without regrowth in the high-dose group of T-SA1–DM1. On the basis of the analysis of luminescence imaging, anti-HER2 scFv–HSA fusion antibodies, especially T-SA1, showed strong and rapid tumor tissue penetrability and distribution compared with trastuzumab. Collectively, the novel type of ADCs is effective and selective targeting to HER2-positive cancer, and may be a promising antitumor drug candidate for further studies.

DDR1 has been identified as a cancer‐associated receptor tyrosine kinase that is highly expressed in several malignancies relative to normal tissues. Clinically approved multi‐kinase inhibitors, such as nilotinib, inhibit DDR1‐mediated tumor growth in xenograft models, suggesting DDR1 might be a potential target for cancer treatments. Here, we employed an antibody‐based strategy with a novel anti‐DDR1 antibody‐drug conjugate (ADC) for colon carcinoma treatment. We developed T 4 H 11 ‐DM4, an ADC targeting DDR1 which carries the tubulin inhibitor payload DM4. Immunohistochemical analysis of a tissue microarray containing 100 colon cancer specimens revealed that DDR1 was highly expressed in 81% of tumor tissues. Meanwhile, high expression of DDR1 was associated with poor survival in patients. In vitro , T 4 H 11 ‐DM4 exhibited potent anti‐proliferative activity with half maximal inhibitory concentration (IC 50 ) values in the nanomolar range in a panel of colon cancer cell lines. In vivo , the antitumor efficacy of T 4 H 11 ‐DM4 was evaluated in three colon cancer cell lines expressing different levels of DDR1. T 4 H 11 ‐DM4 achieved complete tumor regression at doses of 5 and 10 mg·kg −1 in HT‐29 and HCT116 tumor models. Moreover, a correlation between in vivo efficacy of T 4 H 11 ‐DM4 and the levels of DDR1 expression on the cell surface was observed. Tumor cell proliferation was caused by the induction of mitotic arrest, indicating that the antitumor effect in vivo was mediated by DM4. In addition, T 4 H 11 ‐DM4 was efficacious in oxaliplatin‐resistant colon cancer models. In exploratory safety studies, T 4 H 11 ‐DM4 exhibited no overt toxicities when multi‐doses were administered at 10 mg·kg −1 into BALB/c nude mice or when a single dose up to 50 mg·kg −1 was administered into BALB/c mice. Overall, our findings highlight the potential of DDR1‐targeted ADC and may facilitate the development of a new effective therapeutic strategy for colon cancer.

Our data showed that T-DM1 possessed promising antitumor effects on HER2-overexpressing ovarian cancer in mouse model, which provided valuable references for the future clinical trials.