Lobetyolin induces apoptosis of colon cancer cells by inhibiting glutamine metabolism

Abstract

The purpose of the present study was to evaluate the anti‐cancer property of Lobetyolin on colorectal cancer and explore its potential mechanism. Lobetyolin was incubated with HCT‐116 cells in the absence or presence of ASCT2 inhibitor Benser or p53 inhibitor Pifithrin‐α. The levels of glutamine, glutamic acid, α‐ketoglutarate, ATP and GSH were determined to measure the glutamine metabolism. Annexin V‐FITC/PI staining and TUNEL assay were applied to estimate the apoptotic condition. The levels of ASCT2 were examined by RT‐qPCR, Western blot and immunofluorescence staining. The expressions of cleaved‐caspase‐3, caspase‐3, cleaved‐caspase‐7, caspase‐7, cleaved‐PARP, PARP, p53, p21, bax and survivin were detected using Western blot analysis. As a result, the treatment with Lobetyolin effectively induced apoptosis and glutamine metabolism in HCT‐116 cells through ASCT2 signalling. The inhibition of ASCT2 reduced the glutamine‐related biomarkers and augmented the apoptotic process. We further found that the effect of Lobetyolin on HCT‐116 was related to the expressions of p21 and bax, and transportation of p53 to nucleus. The inhibition of p53 by Pifithrin‐α promoted the inhibitory effect of Lobetyolin on ASCT2‐mediated apoptosis. Lobetyolin also exerted anti‐cancer property in nude mice. In conclusion, the present work suggested that Lobetyolin could induce the apoptosis via the inhibition of ASCT2‐mediated glutamine metabolism, which was possibly governed by p53.

Anticancer Properties of Lobetyolin, an Essential Component of Radix Codonopsis (Dangshen)

“…The drug blocked the transportation of the tumor suppressor protein p53 to the cell nucleus and thus modulates the expression of several genes implicated in glutamine metabolism and apoptosis of the cancer cells. A profound down-regulation of the ASCT2 gene and protein was observed, resulting in a marked antitumor effect when mice bearing subcutaneous HCT116 tumors were treated with LBT, intraperitoneally at 10-40 mg/kg [61]. The blockade of glutamine metabolism represents an interesting approach to reduce cancer cell growth, by depriving the cells of the fuel which they need to proliferate [64].…”

“…Several polyacetylene glycosides display anti-inflammatory properties [88][89][90][91][92], such as coreosides A-D which are potent inhibitors of cyclooxygenase-2 [93]. Illustration of the mechanism of action of LBT which was shown to block the transport of the tumor suppressor p53 from the cytoplasm to the nucleus, thereby modulating gene expression and inducing apoptosis of HCT-116 colon cancer cells [61]. Through this p53-dependent mechanism, the drug decreases the content of glutamine and glutamic acid, and down-regulates the expression of the amino acid transporter ASCT2 at the mRNA and proteins lev-els.…”

Beyond Alkaloids: Novel Bioactive Natural Products From Lobelia Species

“…Ishimaru et al, isolated two new polyacetylene compounds lobetyolin 20 and lobetyol 21 from the hairy roots of Lobelia inflata ( Ishimaru et al, 1991 ) . Recently, He et al studied the effect of lobetyolin on colorectal cancer ( He et al, 2020 ). They found that lobetyolin induces colon cancer cells by inhibiting the ASCT2-mediated glutamine metabolism.…”

Genome-wide characterization of SPL gene family in Codonopsis pilosula reveals the novel roles of CpSPL2 and CpSPL10 in promoting the accumulation of secondary metabolites and growth of C. pilosula hairy root

“…Lobetyolin, alkaloids, polysaccharides, and saponins are the major active ingredients in Dangshen, which are responsible for most of the pharmacological functions found in the medicine [34]. Lobetyolin, a general marker compound in Dangshen, has been well reported to exert multiple bioactivities, such as anti-cancer, antiviral, anti-in ammatory, anti-oxidative, mucosal protective, and xanthine oxidase inhibiting properties [35,36].…”