Biotechnological Potential of Araucaria angustifolia Pine Nuts Extract and the Cysteine Protease Inhibitor AaCI-2S

A Novel Trypsin Kunitz-Type Inhibitor from Cajanus cajan Leaves and Its Inhibitory Activity on New Cancer Serine Proteases and Its Effect on Tumor Cell Growth

A novel trypsin inhibitor from Cajanus cajan (TIC) fresh leaves was partially purified by affinity chromatography. SDS-PAGE revealed one band with about 15 kDa with expressive trypsin inhibitor activity by zymography. TIC showed high affinity for trypsin (Ki = 1.617 μM) and was a competitive inhibitor for this serine protease. TIC activity was maintained after 24 h of treatment at 70 °C, after 1 h treatments with different pH values, and β-mercaptoethanol increasing concentrations, and demonstrated expressive structural stability. However, the activity of TIC was affected in the presence of oxidizing agents. In order to study the effect of TIC on secreted serine proteases, as well as on the cell culture growth curve, SK-MEL-28 metastatic human melanoma cell line and CaCo-2 colon adenocarcinoma was grown in supplemented DMEM, and the extracellular fractions were submitted salting out and affinity chromatography to obtain new secreted serine proteases. TIC inhibited almost completely, 96 to 89%, the activity of these serine proteases and reduced the melanoma and colon adenocarcinoma cells growth of 48 and 77% respectively. Besides, it is the first time that a trypsin inhibitor was isolated and characterized from C. cajan leaves and cancer serine proteases were isolated and partial characterized from SK-MEL-28 and CaCo-2 cancer cell lines. Furthermore, TIC shown to be potent inhibitor of tumor protease affecting cell growth, and can be one potential drug candidate to be employed in chemotherapy of melanoma and colon adenocarcinoma.

Plant Kunitz Inhibitors and Their Interaction with Proteases: Current and Potential Pharmacological Targets

The action of proteases can be controlled by several mechanisms, including regulation through gene expression; post-translational modifications, such as glycosylation; zymogen activation; targeting specific compartments, such as lysosomes and mitochondria; and blocking proteolysis using endogenous inhibitors. Protease inhibitors are important molecules to be explored for the control of proteolytic processes in organisms because of their ability to act on several proteases. In this context, plants synthesize numerous proteins that contribute to protection against attacks by microorganisms (fungi and bacteria) and/or invertebrates (insects and nematodes) through the inhibition of proteases in these organisms. These proteins are widely distributed in the plant kingdom, and are present in higher concentrations in legume seeds (compared to other organs and other botanical families), motivating studies on their inhibitory effects in various organisms, including humans. In most cases, the biological roles of these proteins have been assigned based mostly on their in vitro action, as is the case with enzyme inhibitors. This review highlights the structural evolution, function, and wide variety of effects of plant Kunitz protease inhibitors, and their potential for pharmaceutical application based on their interactions with different proteases.

Acrid-release and bitter-downbearing therapy and banxia xiexin decoction regulate Wnt/β-catenin pathway, inhibit proliferation and invasion, and induce apoptosis in gastric cancer cells

OBJECTIVE

To explore the efficacy of the acrid-release and bitter-downbearing therapy and Banxia Xiexin Decoction (BXD) in treating gastric cancer (GC).

METHODS

BXD was decocted, and serum containing medicine was prepared from rats. The SNU-16 cells were cultured with different concentrations of BXD serum (25, 50, 100 μL/mL). Then, those were treated with BXD and Wnt/β-catenin pathway activator (LiCl) and divided into three groups: Control group, BXD group and BXD+LiCl group. Activation of the Wnt/β-catenin pathway was detected by immunofluorescence staining, qRT-PCR, and western blot. Cell activity, clone formation, invasion, metastasis and apoptosis in each group were examined by MTT, clone formation test, Transwell and flow cytometry. The oxidative stress measures in cells of each group were tested by an oxidative stress kit.

RESULTS

With increasing BXD concentration, the clonogenic ability of cells was inhibited. BXD can inhibit cell activity, clone formation, invasion and metastasis, promote oxidative stress, and induce apoptosis. It can also inhibit the activation of Wnt/β-catenin signaling pathway. A Wnt/β-catenin signaling pathway activator could partially inhibit the action of BXD.

CONCLUSION

BXD participates in GC treatment by inhibiting Wnt/β-catenin signaling pathway, thus inhibiting GC cell activity and clone formation, promoting oxidative stress, and inducing apoptosis.