Screening the active constituents of Chinese medicinal herbs as potent inhibitors of Cdc25 tyrosine phosphatase, an activator of the mitosis-inducing p34cdc2 kinase

Inhibitory ASIC2-mediated calcineurin/NFAT against colorectal cancer by triterpenoids extracted from Rhus chinensis Mill

ETHNOPHARMACOLOGICAL RELEVANCE

Studies have shown that the etiology and pathogenesis of colorectal cancer are closely related to the tumor microenvironment, and the cancer tissue is still in the state of "energy deficit" and has to promote energy generation through high glycolysis. Rhus chinensis Mill is a Chinese herbal medicine used to treat various types of solid tumors in China. Colorectal cancer (CRC) is a heterogeneous disease group caused by abnormal changes in glucose metabolism resulted in lactic acid production, which remodels acidosis.

AIM OF THE STUDY

Although previous studies have shown that the active compounds of Rhus chinensis Mill. can inhibit the proliferation of tumor cells, whether its triterpenoids could effectively regulate glycolysis involved in CRC have not been systematically investigated.

MATERIALS AND METHODS

In this study, the extraction of triterpenoids extract from Rhus chinensis Mill. was obtained, and cell viability assay, the percentage of apoptosis for CRC cells were counted, and matrigel invasion assay and production of lactic acid and glucose uptake assay was determined. we further examined the expression of the key glycolytic enzymes and acid-sending ion channel (ASIC) family members of SW620 cells, and some key proteins in the glycolytic pathway were further verified.

RESULTS

Notably, triterpenoids (TER) of Rhus chinensis Mill. showed effective anti-proliferative activity and significantly altered protein levels associated with CRC cell survival and glycolysis metabolism. TER could down-regulate the expression of ASIC2, in CRC SW620 cell line. Most importantly, the levels of ASIC2 and calcineurin/nuclear factor of activated T cells (NFAT) were also down-regulated by TER. Furthermore, inhibition of activated the ASIC2-mediated calcineurin/NFAT1 pathway and target gene transcript expression of MMP-2 and MMP-9 in parallel to reduce, and resulted in the reduced invasion ability by TER treatment.

CONCLUSION

The potential pathways and targets that involved in glycolysis to excert the anti-CRC effects of main compounds in triterpenoids of Rhus chinensis Mill. were predicted by network pharmacology methods. Our findings thus provided rational evidence that inhibition of the ASIC2-induced calcineurin/NFAT pathway by triterpenoids in Rhus chinensis Mill. profoundly suppressed cell growth and invasion in CRC, which target alternative glycolysis in colorectal tumor cells, may be a useful adjuvant therapy in the treatment of colorectal cancer.

In vitro biological screening of a critically endangered medicinal plant, Atropa acuminata Royle Ex Lindl of north western Himalaya

Atropa acuminata Royle Ex Lindl (Atropa acuminata) under tremendous threat of extinction in its natural habitat. However, the antimicrobial, antileishmanial and anticancer effects of the plant’s extracts have not been reported yet. In the current study, an attempt has been made to evaluate the pharmacological potential of this plant’s extracts against microbes, Leishmania and cancer. The roots, stems and leaves of Atropa acuminata were ground; then, seven different solvents were used alone and in different ratios to prepare crude extracts, which were screened for pharmacological effects. The aqueous, methanolic and ethanolic extracts of all parts carried a broad spectrum of anti-bacterial activities, while no significant activity was observed with combined solvents. Three types of cytotoxicity assays were performed, i.e., haemolytic, brine shrimp and protein kinase assays. The aqueous extract of all the parts showed significant haemolytic activity while n-hexane extracts of roots showed significant activity against brine shrimp. The acetone extracts strongly inhibited protein kinase while the methanolic extracts exhibited significant cytotoxic activity of roots and stem. The anti-leishmanial assays revealed that the methanolic extract of leaves and roots showed significant activity. These findings suggest that this plant could be a potential source of natural product based drugs.

Natural Compounds as Modulators of Cell Cycle Arrest: Application for Anticancer Chemotherapies

Natural compounds from various plants, microorganisms and marine species play an important role in the discovery novel components that can be successfully used in numerous biomedical applications, including anticancer therapeutics. Since uncontrolled and rapid cell division is a hallmark of cancer, unraveling the molecular mechanisms underlying mitosis is key to understanding how various natural compounds might function as inhibitors of cell cycle progression. A number of natural compounds that inhibit the cell cycle arrest have proven effective for killing cancer cells in vitro, in vivo and in clinical settings. Significant advances that have been recently made in the understanding of molecular mechanisms underlying the cell cycle regulation using the chemotherapeutic agents is of great importance for improving the efficacy of targeted therapeutics and overcoming resistance to anticancer drugs, especially of natural origin, which inhibit the activities of cyclins and cyclin-dependent kinases, as well as other proteins and enzymes involved in proper regulation of cell cycle leading to controlled cell proliferation.

High-Throughput Screening to Identify Plant Derived Human LDH-A Inhibitors

Aims

Lactate dehydrogenase (LDH)-A is highly expressed in diverse human malignant tumors, parallel to aggressive metastatic disease, resistance to radiation/chemotherapy and clinically poor outcome. Although this enzyme constitutes a plausible target in treatment of advanced cancer, there are few known LDH-A inhibitors.

Study Design

In this work, we utilized a high-throughput enzyme micro-array format to screen and evaluate > 900 commonly used medicinal plant extracts (0.00001-.5 mg/ml) for capacity to inhibit activity of recombinant full length human LDHA; EC .1.1.1.27.

Methodology

The protein sequence of purified enzyme was confirmed using 1D gel electrophoresis- MALDI-TOF-MS/MS, enzyme activity was validated by oxidation of NADH (500μM) and kinetic inhibition established in the presence of a known inhibitor (Oxalic Acid).

Results

Of the natural extracts tested, the lowest IC₅₀s [<0.001 mg/ml] were obtained by: Chinese Gallnut (Melaphis chinensis gallnut), Bladderwrack (Fucus vesiculosus), Kelp (Laminaria Japonica) and Babul (Acacia Arabica). Forty-six additional herbs contained significant LDH-A inhibitory properties with IC₅₀s [<0.07 mg/ml], some of which have common names of Arjun, Pipsissewa, Cinnamon, Pink Rose Buds/Petals, Wintergreen, Cat’s Claw, Witch Hazel Root and Rhodiola Root.

Conclusion

These findings reflect relative potency by rank of commonly used herbs and plants that contain human LDH-A inhibitory properties. Future research will be required to isolate chemical constituents within these plants responsible for LDH-A inhibition and investigate potential therapeutic application.

Rhus chinensis and Galla Chinensis--folklore to modern evidence: review

The species Rhus chinensis Mill. (Anacardiaceae) is an important representative of the genus Rhus, which contains over 250 individual species found in temperate and tropical regions worldwide. Rhus chinensis has long been used by folk medicine practitioners in Asia. Leaves, roots, stem, bark, fruit and particularly the galls on Rhus chinensis leaves, Galla chinensis, are recognized to have preventative and therapeutic effects on different ailments (such as diarrhea, dysentery, rectal and intestinal cancer, diabetes mellitus, sepsis, oral diseases and inflammation). However, it is critical to separate evidence from anecdote. Fortunately, recent scientific research has revealed that Rhus chinensis compounds possess strong antiviral, antibacterial, anticancer, hepatoprotective, antidiarrheal and antioxidant activities. Moreover, compounds isolated from the stem of Rhus chinensis significantly suppressed HIV-1 activity in vitro. Compounds from this plant were also found to inhibit enamel demineralization in vitro and enhance remineralization of dental enamel with fluoride. This review highlights claims from traditional and tribal medicinal lore and makes a contemporary summary of phytochemical, biological and pharmacological findings on this plant material. It aims to show that the pharmaceutical potential of this plant deserves closer attention.

What's new on CDC25 phosphatase inhibitors

The CDC25 phosphatases are key regulators of cell cycle progression and play a central role in the checkpoint response to DNA damage. Their inhibition may therefore represent a promising therapeutic approach in oncology, and small molecule design strategies are currently leading to the identification of various classes of CDC25 inhibitors. Most structures developed so far are quinonoid-based compounds, but also phosphate surrogates or electrophilic entities. Considering the characteristics of the highly conserved active sites of the enzymes, many mechanisms of action have been proposed for these inhibitors. Quinonoid compounds may oxidize the catalytic site cysteine, but can also be considered as Michaël acceptors capable of reacting with the activated thiolate or other electrophilic entities. Phosphate surrogates are thought to interfere with the arginine residue, leading to reversible enzyme inhibition. But some inhibitors can combine in the same molecule several of these mechanisms, thus by fitting into the active site of the enzyme through one part of the molecule and bringing the reactive moiety in close proximity to the catalytic cysteine. This review summarizes novel classes of inhibitors that show specificity for the CDC25s over other phosphatases, cause cell proliferation inhibition and cell cycle arrest in vitro but also, for several of them, inhibition of xenografted tumoral cell growth in vivo. These promising results confirm the interest of the inhibition of CDC25 phosphatases as an anticancer therapeutic strategy.