Identification of a Highly Expressed 3-Hydroxy-3-Methylglutaryl-CoA Reductase Gene in the Root Tissue of <i>Taraxacum kok-saghyz</i>

Kazakh dandelion (Taraxacum kok-saghyz, Tk) is a rubber-producing plant currently being investigated as a source of natural rubber for industrial applications. Like many other isoprenoids, rubber is a downstream product of the mevalonate pathway. The 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) enzyme catalyzes the conversion of 3-hydroxy-3-methylglutaryl-CoA to mevalonic acid, a key regulatory step in the MVA pathway. Such regulated steps provide targets for increases in isoprenoid and rubber contents via genetic engineering to increase enzyme activities. In this study, we identify a TkHMGR1 gene that is highly expressed in the roots of Kazakh dandelion, the main tissue where rubber is synthesized and stored. This finding paves the way for further molecular and genetic studies of the TkHMGR1 gene, and its role in rubber biosynthesis in Tk and other rubber-producing plants.

Cloning and Expression Analysis on 3-Hydroxy-3-methylglutaryl-coenzyme A Reductase from Aquilaria sinensis

Objective To clone the full-length cDNA of 3-hydroxy-3-methylglutaryl-coenzyme A reductase(HMGR) from Aquilaria sinensis(AsHMGR1) and to analyze its expression profile in different tissues and in response to different treatments.HMGR is the first rate-limiting enzyme for sesquiterpene synthesis in the mevalonate pathway.Methods RT-PCR and RACE were used to clone the full-length cDNA of HMGR from A.sinensis based on the conserved HMGR gene fragments.The bioinformatic analysis was performed on its nucleic acid and protein sequence.The expression profile of AsHMGR1 in different tissues and in response to different treatments was analyzed by quantitative RT-PCR.Results The full-length AsHMGR1 cDNA was 2026 bp,containing a 1719 bp open reading frame which encoded a protein of 572 amino acids.Amino acid sequence homology alignment and phylogenetic analysis demonstrated that AsHMGR1 belonged to the HMGR gene family.The detection of tissue expression patterns showed that AsHMGR1 was mainly expressed in the stem,followed by roots and branches.AsHMGR1 could be stimulated by methyl jasmonate and H2O2to varying degrees in a time-dependent manner.Conclusion These data will provide a foundation for further investigation on AsHMGR1 functions and regulatory mechanisms in sesquiterpene synthesis in A.sinensis.

Effect of cholesterol metabolism on hepatolithiasis

Surgical intervention is currently the primary treatment for hepatolithiasis;how-ever,some patients still experience residual stones and high recurrence rates after surgery.Cholesterol metabolism seems to play an important role in hepatoli-thiasis pathogenesis.A high cholesterol diet is one of the significant reasons for the increasing incidence of hepatolithiasis.Therefore,regular diet and appropriate medical intervention are crucial measures to prevent hepatolithiasis and reduce recurrence rate after surgery.Reducing dietary cholesterol and drugs that increase cholesterol stone solubility are key therapeutic approaches in treating hepato-lithiasis.This article discusses the cholesterol metabolic pathways related to the pathogenesis of hepatolithiasis,as well as food intake and targeted therapeutic drugs.

2-hydroxy-3-methyl anthraquinone promotes apoptosis and inhibits invasion of human hepatocellular carcinoma cells by targeting nicotinamide adenine dinucleotide-dependent protein deacetylase sirtuin-1/cellular tumor antigen p53 signaling pathway

OBJECTIVE: To investigate the anti-liver cancer effect of 2-hydroxy-3-methyl anthraquinone(HMA) and the specific mechanism based on nicotinamide adenine dinucleotidedependent protein deacetylase sirtuin-1(SIRT1)/cellular tumor antigen p53(p53) pathway. METHODS: Cell counting kit-8 method was used to observe the effect of HMA on the activity of human hepatocellular carcinoma cells(Hep G2) cells. At 72 h and 80 μL HMA, the apoptosis rate of Hep G2 cells in each group was measured by flow cytometry. Transwell was used to assay for cell invasion. The protein expression levels of SIRT1, p53, B-cell lymphoma-2(Bcl-2), Bcl-2 associated X protein(Bax), caspase-9(CASP9) and caspase-3(CASP3) were detected by Western Blot. RESULTS: HMA significantly inhibited the proliferation of Hep G2 cells, The half inhibiting concentration(IC50) of the HMA at 24, 48 and 72 h were examined and it were 126.3, 98.6, and 80.55 μM, respectively. Compared with the control group, the apoptosis rate of HMA, Selisistat(EX527), and HMA+ EX527 groups enhanced, while the apoptosis rate of SRT1720 diminished, demonstrating that inhibition of SIRT1 can lead to apoptosis of Hep G2 cells. HMA+ EX527 group had the highest apoptosis rate, the lowest expression of SIRT1 and Bcl-2, and the highest expression of p53, Bax, CASP9 and CASP3. The number of invasions of Hep G2 was significantly reduced after HMA and EX527 intervened. Western blot shows HMA could inhibit SIRT1, promote the expression of p53, and decrease the ratio of Bcl-2/Bax. CONCLUSIONS: HMA induced apoptosis in Hep G2 cells, while inhibiting proliferation and invasion. The mechanism of HMA against HCC may be related to the SIRT1/p53 pathway.

Enhancing production of ergosterol in Pichia pastoris GS115 by over-expression of 3-hydroxy-3-methylglutaryl CoA reductase from Glycyrrhiza uralensis

The rate-limiting enzyme in the mevalonic acid(MVA)pathway which can lead to triterpenoid saponin glycyrrhizic acid(GA)is 3-hydroxy-3-methylglutaryl-CoA reductase(HMGR).In order to reveal the effect of copy number variation in the HMGR gene on the MVA pathway,the HMGR gene from Glycyrrhiza uralensis Fisch.(GuHMGR)was cloned and over-expressed in Pichia pastoris GS115.Six recombinant P.pastoris strains containing different copy numbers of the GuHMGR gene were obtained and the content of ergosterol was analyzed by HPLC.The results showed that all the recombinant P.pastoris strains contained more ergosterol than the negative control and the strains with 8 and 44 copies contained significantly more ergosterol than the other strains.However,as the copy number increased,the content of ergosterol showed an increasing–decreasing–increasing pattern.This study provides a rationale for increasing the content of GA through over-expressing the GuHMGR gene in cultivars of G.uralensis.

Molecular cloning and functional identification of a cDNA encoding 4-hydroxy-3-methylbut-2-enyl diphosphate reductase from Tripterygium wilfordii

The 4-hydroxy-3-methylbut-2-enyl diphosphate reductase(HDR) is the last step key enzyme of the methylerythritol phosphate(MEP) pathway,synthesizing isopentenyl diphosphate and its allyl isomer dimethylallyl diphosphate,which is important for regulation of isoprenoid biosynthesis.Here the full-length cDNA of HDR,designated TwHDR(GenBank Accession No.KJ933412.1),was isolated from Tripterygium wilfordii for the first time.TwHDR has an open reading frame(ORF) of 1386 bp encoding461 amino acids.TwHDR exhibits high homology with HDRs of other plants,with an N-terminal conserved domain and three conserved cysteine residues.TwHDR cDNA was cloned into an expression vector and transformed into an Escherichia coli hdr mutant.Since loss-of-function E.coli hdr mutant is lethal,the result showed that transformation of TwHDR cDNA rescued the E.coli hdr mutant.This complementation assay suggests that the TwHDR cDNA encodes a functional HDR enzyme.The expression of TwHDR was induced by methyl-jasmonate(MJ) in T.wilfordii suspension cells.The expression of TwHDR reached the highest level after 1 h of MJ treatment.These results indicate that we have identified a functional TwHDR enzyme,which may play a pivotal role in the biosynthesis of diterpenoid triptolide in T.wilfordii.

Statins and the risk of colorectal cancer: An updated systematic review and meta-analysis of 40 studies

AIM: To investigate the association between statin use and colorectal cancer risk, we conducted an updated meta-analysis of published studies.

Statins role in cancer prevention and development-recent meta-analyses

The therapeutic indications of 3-hydroxy-3-methylgl-utaryl-coenzyme A （HMG-CoA） reductase inhibitors （statins） include hypercholesterolaemia and the pre-vention of cardiovascular events. Statins are well toler-ated and beyond their unambiguous positive cardio-vascular effects there are a steadily increasing number of pleiotropic actions emerging. In this regard, growth inhibition, apoptosis, anti-infammatory and immuno-modulatory actions have been attributed to statins. The anti-proliferative effects have been the basis for massive preclinical investigations to elucidate a func-tional role for statins in carcinogenesis and tumor cell growth. However, preclinical and clinical studies are conflicting, although there is accumulating evidence that statins are capable to suppress and decrease the incidence and recurrence of some human cancers. Giv-en the fact that statins are well tolerated they might also have some impact in combinations with conven-tional and targeted chemotherapy. While synergism has been shown for many combinations in vitro this does not hold true yet in the clinics. Here we review the rational behind usage of statins in oncological set-tings. Positive effects have been observed in patients with melanoma and cancers from the breast, colon, prostate, lung, liver and hematologic tissues. However, substantial evidence from clinical studies is still weak and confounded by several factors, which are inherent in the study design. The majority of the studies are ob-servational or of retrospective nature. Defnitely, there is substantial need for larger, prospective randomized, placebo-controlled trials. Finally, we conclude that statins at the current status of evidence should not be recommended in the prevention or during progression of any cancers, however, individual statins may have benefcial effects in specifc tumor subgroups.

Food-derived peptides with inhibitory capacity for HMG-CoA reductase activity: a potential nutraceutical for hypercholesterolemia

Cardiovascular diseases(CVDs)are the leading global cause of mortality and disease burden.Statins are the most prescribed lipid-lowering drugs to treat hypercholesterolemia and prevent CVDs.The biochemical mechanism of statins consists of competitive inhibition of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase enzyme(HMG-CoAR),the limiting enzyme in cholesterol biosynthesis.Due to statin intolerance in some patient groups,the search for new inhibitors is a field of great interest.This review focusses on the studies reporting the inhibitory effect of protein hydrolysates and biopeptides on the HMG-CoAR enzyme activity.The analysis of the action mechanism and physicochemical characteristics of the HMG-CoAR inhibitory peptides revealed that the molecular weight,amino acid composition,charge,and polarity are key aspects of the interaction with the HMG-CoAR enzyme.In conclusion,this review reveals the potential of using food peptides as new cholesterol-lowering agents and opens a new interesting field of research.However,clinical approaches are mandatory to confirm their therapeutic hypercholesterolemic effect.