Abstract

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. 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. 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). 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. 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.

Highlights

  • Human lactate dehydrogenase is a tetrameric enzyme [1] highly expressed in smooth muscle

  • A screening validation process was established using 0.02 U/ml LDH-A over 75 minutes (Fig. 1b) ± a known inhibitor; oxalic acid (Fig. 1c)

  • The enzyme used in this screening, was described as a recombinant full length Human LDHA with N terminal His tag; 352 amino acids with tag, MW 38.8 kDa: Enzyme Commission (EC) Number 1.1.1.27 (BRENDA | IUBMB) (Abcam, Cambridge, MA), we confirmed the identity of the enzyme using Matrix Assisted Laser Desorption Ionisation (MALDI) Mass Spec (MS/MS) and analysis by Mascot ID (Fig. 2)

Read more

Summary

Introduction

Human lactate dehydrogenase is a tetrameric enzyme [1] highly expressed in smooth muscle. Unlike normal differentiated cells where lactate accumulation occurs anaerobically, cancer cells readily convert glucose into lactate aerobically, a phenomenon termed the Warburg effect [12]. Elevated protein expression or enzyme function of LDH–A is a contributor to accumulated lactate, and aggressive tumor growth [13], advanced progression [14], metastasis [15,16,17], acidity [18], and subsequent resistance to radiation and chemotherapy [19,20,21,22]. LDH–A knockdown, or lowering the functional capacity of LDH-A can suppress tumor growth and metastasis [23], indicating that this enzyme could serve as a novel targeted cancer therapy strategy. We elucidate LDH–A inhibitory effects of commonly used medicinal herbal extracts rom around the world

Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call