Cinnamic acid derivatives as inhibitors for chorismatases and isochorismatases

Chorismate- and isochorismate converting enzymes: versatile catalysts acting on an important metabolic node

Chorismate and isochorismate represent an important branching point connecting primary and secondary metabolism in bacteria, fungi, archaea and plants. Chorismate- and isochorismate-converting enzymes are potential targets for new bioactive compounds, as well as valuable biocatalysts for the in vivo and in vitro synthesis of fine chemicals. The diversity of the products of chorismate- and isochorismate-converting enzymes is reflected in the enzymatic three-dimensional structures and molecular mechanisms. Due to the high reactivity of chorismate and its derivatives, these enzymes have evolved to be accurately tailored to their respective reaction; at the same time, many of them exhibit a fascinating flexibility regarding side reactions and acceptance of alternative substrates. Here, we give an overview of the different (sub)families of chorismate- and isochorismate-converting enzymes, their molecular mechanisms, and three-dimensional structures. In addition, we highlight important results of mutagenetic approaches that generate a broader understanding of the influence of distinct active site residues for product formation and the conversion of one subfamily into another. Based on this, we discuss to what extent the recent advances in the field might influence the general mechanistic understanding of chorismate- and isochorismate-converting enzymes. Recent discoveries of new chorismate-derived products and pathways, as well as biocatalytic conversions of non-physiological substrates, highlight how this vast field is expected to continue developing in the future.

Knockdown of ISOC1 suppresses cell proliferation in pancreatic cancer in vitro

Pancreatic cancer is a deadly disease that is frequently associated with mortality at the time of diagnosis due to rapid metastasis, which makes it unsuitable for operative surgery, and resistant to chemotherapy and radiation therapy. Isochorismatase domain-containing protein 1 (ISOC1) has putative isochorismatase activity, and is positively regulated by estrogen in human breast cancer. However, its role in pancreatic cancer has yet to be fully elucidated. Analysis from datasets downloaded from The Cancer Genome Atlas and Genotype-Tissue Expression databases indicated that the ISOC1 mRNA expression level was increased in pancreatic cancer tissues, compared with normal pancreatic tissues. In the present study, it was determined that the human pancreatic cancer cell lines SW 1990, PANC-1 and AsPC-1 had increased expression levels of ISOC1 mRNA, compared with human pancreatic ductal epithelial cells. Additionally, two of the pancreatic cancer cell lines, SW 1990 and PANC-1, transfected with lentivirus-delivered short hairpin RNA, to knockdown the expression of ISOC1, were established. Cell counting and MTT assays indicated that knockdown of ISOC1 decreased the ability of cell growth and proliferation in pancreatic cancer cells. Furthermore, Annexin V staining and caspase-3/7 activity assays demonstrated that inhibition of ISOC1 promoted cell apoptosis via elevation of the expression of caspase-3/7. Furthermore, inhibition of ISOC1 impaired the cell migration and invasive capability of the cells. In conclusion, ISOC1 exerts a role in pancreatic cancer cell growth and apoptosis, and may have a role in pancreatic cancer tumorigenesis.

Chorismatases – the family is growing

A newly discovered subfamily of chorismatases catalyses the same reaction as chorismate lyases (cleavage of chorismate to 4-hydroxybenzoate), but does not suffer from product inhibition.

BZML, a novel colchicine binding site inhibitor, overcomes multidrug resistance in A549/Taxol cells by inhibiting P-gp function and inducing mitotic catastrophe

Multidrug resistance (MDR) interferes with the efficiency of chemotherapy. Therefore, developing novel anti-cancer agents that can overcome MDR is necessary. Here, we screened a series of colchicine binding site inhibitors (CBSIs) and found that 5-(3, 4, 5-trimethoxybenzoyl)-4-methyl-2-(p-tolyl) imidazol (BZML) displayed potent cytotoxic activity against both A549 and A549/Taxol cells. We further explored the underlying mechanisms and found that BZML caused mitosis phase arrest by inhibiting tubulin polymerization in A549 and A549/Taxol cells. Importantly, BZML was a poor substrate for P-glycoprotein (P-gp) and inhibited P-gp function by decreasing P-gp expression at the protein and mRNA levels. Cell morphology changes and the expression of cycle- or apoptosis-related proteins indicated that BZML mainly drove A549/Taxol cells to die by mitotic catastrophe (MC), a p53-independent apoptotic-like cell death, whereas induced A549 cells to die by apoptosis. Taken together, our data suggest that BZML is a novel colchicine binding site inhibitor and overcomes MDR in A549/Taxol cells by inhibiting P-gp function and inducing MC. Our study also offers a new strategy to solve the problem of apoptosis-resistance.