Chinese herbal medicine-derived compounds for cancer therapy: A focus on hepatocellular carcinoma

Ethnopharmacological relevance

Hepatocellular carcinoma (HCC) as the major histological subtype of primary liver cancer remains one of the most common malignancies worldwide. Due to the complicated molecular pathogenesis of HCC, the option for effective systemic treatment is quite limited. There exists a critical need to explore and evaluate possible alternative strategies for effective control of HCC. With a long history of clinical use, Chinese herbal medicine (CHM) is emerging as a noticeable choice for its multi-level, multi-target and coordinated intervention effects against HCC. With the aids of phytochemistry and molecular biological approaches, in the past decades many CHM-derived compounds have been carefully studied through both preclinical and clinical researches and have shown great potential in novel anti-HCC natural product development. The present review aimed at providing the most recent developments on anti-HCC compounds derived from CHM, especially their underlying pharmacological mechanisms.

Materials and methods

A systematic search of anti-HCC compounds from CHM was carried out focusing on literatures published both in English (PubMed, Scopus, Web of Science and Medline) and in Chinese academic databases (Wanfang and CNKI database).

Results

In this review, we tried to give a timely and comprehensive update about the anti-HCC effects and targets of several representative CHM-derived compounds, namely curcumin, resveratrol, silibinin, berberine, quercetin, tanshinone II-A and celastrol. Their mechanisms of anti-HCC behaviors, potential side effects or toxicity and future research directions were discussed.

Conclusion

Herbal compounds derived from CHM are of much significance in devising new drugs and providing unique ideas for the war against HCC. We propose that these breakthrough findings may have important implications for targeted-HCC therapy and modernization of CHM.     

UGT1A6基因多态性与癫痫患者丙戊酸血药浓度相关性研究

目的：探讨尿苷二磷酸葡萄糖醛酰转移酶（UGT）1A6基因多态性对癫痫患者丙戊酸血药浓度的影响。方法：对40例癫痫患者应用限制性酶切片段多态性技术分析中国汉族人常见的UGT1A6552A＞C等位基因变异,应用荧光偏振免疫法测定患者丙戊酸的血药浓度,在进行标准化以排除剂量和体重对血药浓度的影响后,分析不同UGT1A6基因型患者丙戊酸血药浓度的差异。结果：UGT1A6552A＞C等位基因频率为0.2625,符合Hardy-Weinberg平衡。将患者分为 AA野生纯合子型慢代谢组和AC合并AA突变型快代谢组,慢代谢组的丙戊酸标准化血药浓度显著高于快代谢组（P＜0.01）。结论：UGT1A6552A＞C基因多态性与丙戊酸的血药浓度有相关性,该位点突变可导致丙戊酸血药浓度降低。     

Polymorphisms of human cytochrome P450 2C9 and the functional relevance

Human cytochrome P450 2C9 (CYP2C9) accounts for ∼20% of hepatic total CYP content and metabolizes ∼15% clinical drugs such as phenytoin, S-warfarin, tolbutamide, losartan, and many nonsteroidal anti-inflammatory agents (NSAIDs). CYP2C9 is highly polymorphic, with at least 33 variants of CYP2C9 (*1B through *34) being identified so far. CYP2C9*2 is frequent among Caucasians with ∼1% of the population being homozygous carriers and 22% are heterozygous. The corresponding figures for the CYP2C9*3 allele are 0.4% and 15%, respectively. There are a number of clinical studies addressing the impact of CYP2C9 polymorphisms on the clearance and/or therapeutic response of therapeutic drugs. These studies have highlighted the importance of the CYP2C9*2 and *3 alleles as a determining factor for drug clearance and drug response. The CYP2C9 polymorphisms are relevant for the efficacy and adverse effects of numerous NSAIDs, sulfonylurea antidiabetic drugs and, most critically, oral anticoagulants belonging to the class of vitamin K epoxide reductase inhibitors. Warfarin has served as a practical example of how pharmacogenetics can be utilized to achieve maximum efficacy and minimum toxicity. For many of these drugs, a clear gene–dose and gene–effect relationship has been observed in patients. In this regard, CYP2C9 alleles can be considered as a useful biomarker in monitoring drug response and adverse effects. Genetic testing of CYP2C9 is expected to play a role in predicting drug clearance and conducting individualized pharmacotherapy. However, prospective clinical studies with large samples are warranted to establish gene–dose and gene–effect relationships for CYP2C9 and its substrate drugs.     

Preclinical factors affecting the interindividual variability in the clearance of the investigational anti-cancer drug 5,6-dimethylxanthenone-4-acetic acid

Cancer chemotherapy is characterized by significant interindividual variations in systemic clearance, therapeutic response, and toxicity. These variations are due mainly to genetic factors, leading to alterations in drug metabolism and/or target proteins. The aim of this study was to determine, using a human liver bank (N=14), the interindividual variations in the expression and activity of liver enzymes that metabolize the investigational anticancer drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA), i.e cytochrome P450 (CYP1A2) and uridine diphosphate glucuronosyltransferase (UGT1A9/2B7). In addition, interindividual variations in enzyme inhibition, hydrolysis of DMXAA acyl glucuronide (DMXAA-G) by plasma and hepatic microsomes, and the binding of DMXAA by plasma proteins also were examined. The results indicated that there was approximately one order of magnitude of interindividual variation in the expression of CYP1A2 and UGT2B7, activity of the enzymes toward DMXAA, and inhibition potency (IC(50)) by diclofenac, cyproheptadine, and alpha-naphthoflavone. The enzyme activities toward DMXAA and IC(50) values were closely correlated with enzyme expression. There was a smaller (2- to 3-fold) variation in the enzyme-catalyzed hydrolysis of DMXAA acyl glucuronide in human plasma and liver microsomes (N=6) and in the binding of DMXAA by plasma proteins in humans. In conclusion, the interindividual variability of DMXAA disposition observed in vitro might reflect the greater elimination variability (>one order of magnitude) in Phase I cancer patients. The variability in DMXAA clearance in these cancer patients would be due mainly to differences in its metabolism and its metabolic inhibition by co-administered drugs. To a lesser extent, variability in the clearance of DMXAA could be due to the hydrolysis of its acyl glucuronide and/or its binding to plasma proteins. Further study is needed to examine the genotype-phenotype relationship, and the result, together with therapeutic drug monitoring may provide a useful strategy for optimizing DMXAA treatment.     

人类UGT2B17基因缺失的多重PCR分型方法

目的建立一种快速有效的人类UGT2B17基因缺失型的PCR分型方法。方法针对人类基因组UGT2B17基因缺失型和外显子序列设计引物,采用多重PCR法进行分型。结果成功建立了一种多重PCR基因分型方法,并以普通PCR法和测序法验证。对安徽皖南地区健康人群UGT2B17基因分布进行了初步分析。结论所建立的多重PCR方法为一种有效便捷的UGT2B17基因缺失分型方法。     

In vitro ex vivo assessment of Morinda citrifolia on drug metabolizing enzymes in spontaneously hypertensive rats

Morinda citrifolia Linn. (Rubiaceae), common name noni, has been used as a herbal medicine for over 2000 years. The consumption of noni, and especially the fruit, stresses the importance, urgency, and possibility of the examination of drug interaction when concomitantly administered with a drug. The objectives of this study were to determine the effects of noni juice (NJ) on aminopyrine N-demethylase (APND), uridine diphosphoglucuronosyl-transferase (UGT), and cytosolic glutathione S-transferase (GST) drug metabolizing enzymes and the molecular mechanism elucidation of NJ on APND using different inhibitors and stimulators. The in vitro results for APND showed that different concentrations of NJ significantly increased the activity in isolated hepatocytes at 1.0?ng/mL, 10?ng/mL, 10?μg/mL, 20?μg/mL, 50?μg/mL, and 100?μg/mL. The ex vivo results demonstrated that NJ (210?mg/kg) produced a statistically significant increase in APND activity following 1 day of NJ treatment. The results for UGT and GST showed a decrease in the activity of UGT at a dose of 21?mg/kg following 1 day of treatment, and at 2.1 and 21?mg/kg following 14 days of treatment. GST enzyme demonstrated an increase in activity by 100% for all doses following 1 day of treatment. Molecular mechanism elucidation of the ex vivo effect of NJ on phase I APND showed that KT5720 significantly reduced the activity as compared to control. A change in activity of APND, UGT, and GST following 1 day and 14 days of treatment suggests that all three metabolic pathways may play a role in herb–drug interaction by modulation of metabolic enzymes.     

Multiple variants in UGT1A1 gene are factors to develop indirect hyper-bilirubinemia

Most Taiwanese patients with hyper-bilirubinemia have genetic abnormalities in the uridine diphosphoglucuronate-glucuronosyltransferase 1A1 (UGT1A1) gene beyond the variants in the TATA box upstream of UGT1A1 associated with Gilbert’s syndrome. To investigate the role of UGT1A1 in the pathogenesis of indirect hyper-bilirubinemia, we prospectively studied 97 consecutive patients with indirect hyper-bilirubinemia for genotypes of promoter [(TA)₆TAA6, (TA)₇TAA7] and coding region [nucleotide (nt)-211, nt-686, nt-1,091 and nt-1,456] of UGT1A1. Thirty-six of the patients (45.6%) were found to have Gilbert’s syndrome with 7/7 genotype; among them, 14 also carried variants at nt-686. Forty-two patients (43.3%) had the 6/7 genotype; among them, 36 patients were found to have one or more variants in the coding region. Patients with higher serum total bilirubin are associated with higher likelihood of carrying Gilbert’s syndrome genotype: 60.0% (P=0.007) patients with serum total bilirubin level ≥2.5 mg/dL carried the Gilbert’s syndrome genotype, while only 23.9% of patients with serum total bilirubin level <2.5 mg/dL carry the same genotype (P=0.0006). Forty-one of the 61 non-Gilbert’s patients had one homogenous variants or two or more heterozygous variants in UGT1A1. Further studies are necessary to confirm the role of one homo-zygous variant or two or more hetero-zygous variants in UGT1A1 gene as factors for indirect hyper-bilirubinemia.     

Characterization of in vitro metabolites of cudratricusxanthone A in human liver microsomes

Cudratricusxanthone A (CTXA), isolated from the roots of Cudrania tricuspidata, exhibits several biological activities; however, metabolic biotransformation was not investigated. Therefore, metabolites of CTXA were investigated and the major metabolic enzymes engaged in human liver microsomes (HLMs) were characterized using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). CTXA was incubated with HLMs or human recombinant CYPs and UGTs, and analysed by an LC‐MS/MS equipped electrospray ionization (ESI) to qualify and quantify its metabolites. In total, eight metabolites were identified: M1–M4 were identified as mono‐hydroxylated metabolites during Phase I, and M5–M8 were identified as O‐glucuronidated metabolites during Phase II in HLMs. Moreover, these metabolite structures and a metabolic pathway were identified by elucidation of MSⁿ fragments and formation by human recombinant enzymes. M1 was formed by CYP2D6, and M2–M4 were generated by CYP1A2 and CYP3A4. M5–M8 were mainly formed by UGT1A1, respectively. While investigating the biotransformation of CTXA, eight metabolites of CTXA were identified by CYPs and UGTs; these data will be valuable for understanding the in vivo metabolism of CTXA. Copyright © 2015 John Wiley & Sons, Ltd.     

广西三江县侗族新生儿UGT1A1基因变异分析北大核心CSCD

目的探讨广西柳州三江县侗族新生儿UGT1A1基因变异特点及其与侗族新生儿高胆红素血症发生的关系。方法前瞻性选取2021年1月至2022年1月于三江县人民医院新生儿科诊断不明原因高胆红素血症的新生儿84例为研究对象;另选取同期健康新生儿60例纳入健康对照组。提取两组新生儿外周血基因组DNA,对UGT1A1启动子区TATA盒和外显子1进行PCR扩增并进行基因测序。结果病例组检测出33例G71R错义突变,突变率为39%,A等位基因频率(21%)显著高于健康对照组(10%)(P<0.05)。携带G71R错义突变基因型的侗族新生儿发生高胆红素血症的风险是携带野生型的健康新生儿的2.588倍(P<0.05)。Hardy-Weinberg遗传平衡检验结果提示两组新生儿UGT1A1 G71R位点基因型符合遗传平衡(P>0.05)。结论UGT1A1 G71R突变是三江县侗族新生儿高频基因变异类型,且G71R错义突变与侗族新生儿发生高胆红素血症相关。