Aristolochic Acid in the Etiology of Renal Cell Carcinoma

Aristolochic acid-related renal cell carcinoma exhibits a distinct tumor-immune microenvironment favoring response to immune checkpoint blockade

Immune checkpoint blockade (ICB) is currently the standard of care for metastatic renal cell carcinoma (RCC), but treatment responses remain unpredictable. Aristolochic acid (AA), a prevalent supplement additive in Taiwan, has been associated with RCC and induces signature mutations, although its effect on the tumor-immune microenvironment (TIME) is unclear. We aimed to investigate the immune profile of AA-positive RCCs and explore its potential role as a susceptible candidate for ICB. Tissue samples from 22 patients with clear cell RCC (ccRCC) were collected for whole-exome sequencing to determine the genetic features and AA mutational signature (the discovery cohort). The corresponding RNA was sent for NanoString PanCancer IO 360 gene expression analysis to explore the immunological features. The formalin-fixed, parafilm-embedded slides of ccRCCs were sent for multiplex immunohistochemistry/immunofluorescence stain using Vectra system to evaluate the TIME. Tissues from two patients with metastatic RCC demonstrating complete response to ICB were sent for studies to validate the findings (the index patients). The results showed that AA mutational signatures with high tumor mutational burden (TMB) were present in 31.81% of the tumors in the discovery cohort. Three distinct clusters were observed through NanoString analysis. Clusters 1 and 3 were composed mainly of AA-positive RCCs. Cluster 3 RCCs exhibited higher tumor inflammation signature scores and higher immune cell type scores. Vectra analysis revealed a higher percentage of CD15+ and BATF3+ cells in cluster 1, whereas the percentage of CD8+ cells was potentially higher in cluster 3. Strong AA mutational signatures were found in the tumors of two index patients, and both were grouped to cluster 3. In conclusion, AA may induce higher TMB and alter the immune microenvironment in RCCs, which makes the tumors more susceptible to ICB. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Unveiling correlations between aristolochic acids and liver cancer: spatiotemporal heterogeneity phenomenon

Aristolochic acids are a class of naturally occurring compounds in Aristolochiaceae that have similar structural skeletons and chemical properties. Exposure to aristolochic acids is a risk factor for severe kidney disease and urinary system cancer. However, the carcinogenicity of aristolochic acids to the liver, which is the main site of aristolochic acid metabolism, is unclear. Although the characteristic fingerprint of aristolochic acid-induced mutations has been detected in the liver and aristolochic acids are known to be hepatotoxic, whether aristolochic acids can directly cause liver cancer is yet to be verified. This review summarizes the findings of long-term carcinogenicity studies of aristolochic acids in experimental animals. We propose that spatiotemporal heterogeneity in the carcinogenicity of these phytochemicals could explain why direct evidence of aristolochic acids causing liver cancer has never been found in adult individuals. We also summarized the reported approaches to mitigate aristolochic acid-induced hepatotoxicity to better address the associated global safety issue and provide directions and recommendations for future investigation.

Molecular and immune pathobiology of human angiosarcoma

Angiosarcoma is a rare endothelial-derived malignancy that is extremely diverse in anatomy, aetiology, molecular and immune characteristics. While novel therapeutic approaches incorporating targeted agents and immunotherapy have yielded significant improvements in patient outcomes across several cancers, their impact on angiosarcoma remains modest. Contributed by its heterogeneous nature, there is currently a lack of novel drug targets in this disease entity and no reliable biomarkers that predict response to conventional treatment. This review aims to examine the molecular and immune landscape of angiosarcoma in association with its aetiology, anatomical sites, prognosis and therapeutic options. We summarise current efforts to characterise angiosarcoma subtypes based on molecular and immune profiling. Finally, we highlight promising technologies such as single-cell spatial "omics" that may further our understanding of angiosarcoma and propose strategies that can be similarly applied for the study of other rare cancers.

Structural and mechanistic insights into the transport of aristolochic acids and their active metabolites by human serum albumin

Aristolochic acids I and II (AA-I/II) are carcinogenic principles of Aristolochia plants, which have been employed in traditional medicinal practices and discovered as food contaminants. While the deleterious effects of AAs are broadly acknowledged, there is a dearth of information to define the mechanisms underlying their carcinogenicity. Following bioactivation in the liver, N-hydroxyaristolactam and N-sulfonyloxyaristolactam metabolites are transported via circulation and elicit carcinogenic effects by reacting with cellular DNA. In this study, we apply DNA adduct analysis, X-ray crystallography, isothermal titration calorimetry, and fluorescence quenching to investigate the role of human serum albumin (HSA) in modulating AA carcinogenicity. We find that HSA extends the half-life and reactivity of N-sulfonyloxyaristolactam-I with DNA, thereby protecting activated AAs from heterolysis. Applying novel pooled plasma HSA crystallization methods, we report high-resolution structures of myristic acid-enriched HSA (HSAMYR) and its AA complexes (HSAMYR/AA-I and HSAMYR/AA-II) at 1.9 Å resolution. While AA-I is located within HSA subdomain IB, AA-II occupies subdomains IIA and IB. ITC binding profiles reveal two distinct AA sites in both complexes with association constants of 1.5 and 0.5 · 106 M-1 for HSA/AA-I versus 8.4 and 9.0 · 105 M-1 for HSA/AA-II. Fluorescence quenching of the HSA Trp214 suggests variable impacts of fatty acids on ligand binding affinities. Collectively, our structural and thermodynamic characterizations yield significant insights into AA binding, transport, toxicity, and potential allostery, critical determinants for elucidating the mechanistic roles of HSA in modulating AA carcinogenicity.

Risk of secondary primary malignancies in survivors of upper tract urothelial carcinoma: A nationwide population-based analysis

BACKGROUND

To investigate the cancer types and risk factors of secondary primary malignancy (SPM) in patients with upper tract urothelial carcinoma (UTUC) in Taiwan.

METHODS

Using National Health Insurance Research Dataset and catastrophic illness registry, we enrolled newly diagnosed UTUC patients from 2000 to 2013. Those without catastrophic illness registration were excluded from the study. The cancer types and hazard ratios (HRs) of subsequent SPMs were calculated according to the antecedent malignancy. We analyzed the risk factors for developing SPMs using multivariate Cox proportional hazard models.

RESULTS

A total of 9050 UTUC patients were registered and 2187 (24.2%) patients developed SPMs during the study period. As compared with primary UTUC, the relative risk ratios of SPM was 2.5 folds and 18% higher in those with antecedent non-UC malignancy and with bladder cancer history, respectively. Totally, 387 (37.8%) of 1022 UTUC patients with antecedent non-UC malignancy developed subsequent SPM after UTUC diagnosis. The antecedent and subsequent cancer types are similar and kidney cancer is most common, followed by hepatoma. Multivariate analysis showed that a history of antecedent non-UC malignancy is the most unfavorable factor for SPM development (HR, 2.50; 95% CI, 2.23-2.81), followed by liver disease, male gender, antecedent bladder cancer history, age ≥ 75 years, and chronic kidney disease.

CONCLUSIONS

Our study, conducted in Taiwan and involving 9050 UTUC patients, meticulously examined the types of SPM and the associated risk factors. Our research unearthed several pivotal discoveries: a preceding history of non-UC malignancies emerged as the single most influential factor contributing to the occurrence of subsequent cancers, followed by liver disease, male gender, antecedent bladder cancer history, age ≥75 years, and chronic kidney disease. Futhermore, kidney cancer emerged as the predominant subsequent malignancy, closely trailed by hepatoma..

Tissue Organoid Cultures Metabolize Dietary Carcinogens Proficiently and Are Effective Models for DNA Adduct Formation

Human tissue three-dimensional (3D) organoid cultures have the potential to reproduce in vitro the physiological properties and cellular architecture of the organs from which they are derived. The ability of organoid cultures derived from human stomach, liver, kidney, and colon to metabolically activate three dietary carcinogens, aflatoxin B1 (AFB1), aristolochic acid I (AAI), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), was investigated. In each case, the response of a target tissue (liver for AFB1; kidney for AAI; colon for PhIP) was compared with that of a nontarget tissue (gastric). After treatment cell viabilities were measured, DNA damage response (DDR) was determined by Western blotting for p-p53, p21, p-CHK2, and γ-H2AX, and DNA adduct formation was quantified by mass spectrometry. Induction of the key xenobiotic-metabolizing enzymes (XMEs) CYP1A1, CYP1A2, CYP3A4, and NQO1 was assessed by qRT-PCR. We found that organoids from different tissues can activate AAI, AFB1, and PhIP. In some cases, this metabolic potential varied between tissues and between different cultures of the same tissue. Similarly, variations in the levels of expression of XMEs were observed. At comparable levels of cytotoxicity, organoids derived from tissues that are considered targets for these carcinogens had higher levels of adduct formation than a nontarget tissue.

Screening DNA Damage in the Rat Kidney and Liver by Untargeted DNA Adductomics

Air pollution, tobacco smoke, and red meat are associated with renal cell cancer (RCC) risk in the United States and Western Europe; however, the chemicals that form DNA adducts and initiate RCC are mainly unknown. Aristolochia herbaceous plants are used for medicinal purposes in Asia and worldwide. They are a significant risk factor for upper tract urothelial carcinoma (UTUC) and RCC to a lesser extent. The aristolochic acid (AA) 8-methoxy-6-nitrophenanthro-[3,4-d]-1,3-dioxolo-5-carboxylic acid (AA-I), a component of Aristolochia herbs, contributes to UTUC in Asian cohorts and in Croatia, where AA-I exposure occurs from ingesting contaminated wheat flour. The DNA adduct of AA-I, 7-(2'-deoxyadenosin-N6-yl)-aristolactam I, is often detected in patients with UTUC, and its characteristic A:T-to-T:A mutational signature occurs in oncogenes and tumor suppressor genes in AA-associated UTUC. Identifying DNA adducts in the renal parenchyma and pelvis caused by other chemicals is crucial to gaining insights into unknown RCC and UTUC etiologies. We employed untargeted screening with wide-selected ion monitoring tandem mass spectrometry (wide-SIM/MS2) with nanoflow liquid chromatography/Orbitrap mass spectrometry to detect DNA adducts formed in rat kidneys and liver from a mixture of 13 environmental, tobacco, and dietary carcinogens that may contribute to RCC. Twenty DNA adducts were detected. DNA adducts of 3-nitrobenzanthrone (3-NBA), an atmospheric pollutant, and AA-I were the most abundant. The nitrophenanthrene moieties of 3-NBA and AA-I undergo reduction to their N-hydroxy intermediates to form 2'-deoxyguanosine (dG) and 2'-deoxyadenosine (dA) adducts. We also discovered a 2'-deoxycytidine AA-I adduct and dA and dG adducts of 10-methoxy-6-nitro-phenanthro-[3,4-d]-1,3-dioxolo-5-carboxylic acid (AA-III), an AA-I isomer and minor component of the herbal extract assayed, signifying AA-III is a potent kidney DNA-damaging agent. The roles of AA-III, other nitrophenanthrenes, and nitroarenes in renal DNA damage and human RCC warrant further study. Wide-SIM/MS2 is a powerful scanning technology in DNA adduct discovery and cancer etiology characterization.

No Incidence of Liver Cancer Was Observed in A Retrospective Study of Patients with Aristolochic Acid Nephropathy

OBJECTIVE

To assess the risk of aristolochic acid (AA)-associated cancer in patients with AA nephropathy (AAN).

METHODS

A retrospective study was conducted on patients diagnosed with AAN at Peking University First Hospital from January 1997 to December 2014. Long-term surveillance and follow-up data were analyzed to investigate the influence of different factors on the prevalence of cancer. The primary endpoint was the incidence of liver cancer, and the secondary endpoint was the incidence of urinary cancer during 1 year after taking AA-containing medication to 2014.

RESULTS

A total of 337 patients diagnosed with AAN were included in this study. From the initiation of taking AA to the termination of follow-up, 39 patients were diagnosed with cancer. No cases of liver cancer were observed throughout the entire follow-up period, with urinary cancer being the predominant type (34/39, 87.17%). Logistic regression analysis showed that age, follow-up period, and diabetes were potential risk factors, however, the dosage of the drug was not significantly associated with urinary cancer.

CONCLUSIONS

No cases of liver cancer were observed at the end of follow-up. However, a high prevalence of urinary cancer was observed in AAN patients. Establishing a direct causality between AA and HCC is challenging.

New risk factors and molecular landscapes of hepatic angiosarcoma in the Taiwanese population†

Hepatic angiosarcoma is a rare, highly aggressive malignancy of the liver. The tumorigenesis of hepatic angiosarcoma has been relatively understudied in terms of aetiology and molecular properties. A recent study published in The Journal of Pathology revealed a strong association between hepatic angiosarcoma incidence and chronic kidney disease, particularly in end-stage renal disease using population-based data from the National Health Insurance Research Database in Taiwan and an institutional cohort. The study also revealed enrichment in the mutational signature of aristolochic acid exposure and is the first reported observation of this mutational signature in human sarcomas. © 2023 The Pathological Society of Great Britain and Ireland.

Proteogenomics of clear cell renal cell carcinoma response to tyrosine kinase inhibitor

The tyrosine kinase inhibitor (TKI) Sunitinib is one the therapies approved for advanced renal cell carcinoma. Here, we undertake proteogenomic profiling of 115 tumors from patients with clear cell renal cell carcinoma (ccRCC) undergoing Sunitinib treatment and reveal the molecular basis of differential clinical outcomes with TKI therapy. We find that chromosome 7q gain-induced mTOR signaling activation is associated with poor therapeutic outcomes with Sunitinib treatment, whereas the aristolochic acid signature and VHL mutation synergistically caused enhanced glycolysis is correlated with better prognosis. The proteomic and phosphoproteomic analysis further highlights the responsibility of mTOR signaling for non-response to Sunitinib. Immune landscape characterization reveals diverse tumor microenvironment subsets in ccRCC. Finally, we construct a multi-omics classifier that can detect responder and non-responder patients (receiver operating characteristic-area under the curve, 0.98). Our study highlights associations between ccRCC molecular characteristics and the response to TKI, which can facilitate future improvement of therapeutic responses.

Association between hepatic angiosarcoma and end-stage renal disease: nationwide population-based evidence and enriched mutational signature of aristolochic acid exposure

Hepatic angiosarcoma (HAS) is an aggressive mesenchymal malignancy that remains underexplored with respect to its etiology and mutational landscapes. To clarify the association between HAS and end-stage renal disease (ESRD), we used nationwide data of the National Health Insurance Research Database (NHIRD) in Taiwan, covering ~99% of the population, from 2001 to 2016. To investigate molecular signatures, we performed whole-exome sequencing (WES) in 27 surgical specimens, including nine ESRD-associated cases. The NHIRD analysis demonstrated that HAS ranked second among all angiosarcomas in Taiwan, with the incidence rates of HAS being 0.08, 2.49, and 5.71 per 100,000 person-years in the general population, chronic kidney disease (CKD), and ESRD patients, respectively. The standardized incidence ratios of HAS in CKD and ESRD patients were 29.99 and 68.77, respectively. In comparison with nonhepatic angiosarcoma, the multivariate regression analysis of our institutional cohort confirmed CKD/ESRD as an independent risk factor for HAS (odds ratio: 9.521, 95% confidence interval: 2.995-30.261, p < 0.001). WES identified a high tumor mutation burden (TMB; median: 8.66 variants per megabase) and dominant A:T-to-T:A transversion in HAS with frequent TP53 (81%) and ATRX (41%) mutations, KDR amplifications/gains (56%), and CDKN2A/B deletions (48%). Notably, ESRD-associated HAS had a significantly higher TMB (17.62 variants per megabase, p = 0.01) and enriched mutational signatures of aristolochic acid exposure (COSMIC SBS22, p < 0.001). In summary, a significant proportion of HAS in Taiwan is associated with ESRD and harbors a distinctive mutational signature, which concomitantly links nephrotoxicity and mutagenesis resulting from exposure to aristolochic acid or related compounds. A high TMB may support the eligibility for immunotherapy in treating ESRD-associated HAS. © 2023 The Pathological Society of Great Britain and Ireland.

Integrated analysis of racial disparities in genomic architecture identifies a trans-ancestry prognostic subtype in bladder cancer

The incidence of bladder cancer and patient survival vary greatly among different populations, but the influence of the associated molecular features and evolutionary processes on its clinical treatment and prognostication remains unknown. Here, we analyze the genomic architectures of 505 bladder cancer patients from Asian/Black/White populations. We identify a previously unknown association between AHNAK mutations and activity of the APOBEC-a mutational signature, the activity of which varied substantially across populations. All significantly mutated genes but only half of arm-level somatic copy number alterations (SCNAs) are enriched with clonal events, indicating large-scale SCNAs as rich sources of bladder cancer clonal diversities. The prevalence of TP53 and ATM clonal mutations as well as the associated burden of SCNAs is significantly higher in Whites/Blacks than in Asians. We identify a trans-ancestry prognostic subtype of bladder cancer characterized by enrichment of non-muscle-invasive patients and muscle-invasive patients with good prognosis, increased CREBBP/FGFR3/HRAS/NFE2L2 mutations, decreased intra-tumor heterogeneity and genome instability, and an activated tumor microenvironment.

Proteogenomic characterization of MiT family translocation renal cell carcinoma

Microphthalmia transcription factor (MiT) family translocation renal cell carcinoma (tRCC) is a rare type of kidney cancer, which is not well characterized. Here we show the comprehensive proteogenomic analysis of tRCC tumors and normal adjacent tissues to elucidate the molecular landscape of this disease. Our study reveals that defective DNA repair plays an important role in tRCC carcinogenesis and progression. Metabolic processes are markedly dysregulated at both the mRNA and protein levels. Proteomic and phosphoproteome data identify mTOR signaling pathway as a potential therapeutic target. Moreover, molecular subtyping and immune infiltration analysis characterize the inter-tumoral heterogeneity of tRCC. Multi-omic integration reveals the dysregulation of cellular processes affected by genomic alterations, including oxidative phosphorylation, autophagy, transcription factor activity, and proteasome function. This study represents a comprehensive proteogenomic analysis of tRCC, providing valuable insights into its biological mechanisms, disease diagnosis, and prognostication.

Aristolochic acid-associated cancers: a public health risk in need of global action

Aristolochic acids (AAs) are a group of naturally occurring compounds present in many plant species of the Aristolochiaceae family. Exposure to AA is a significant risk factor for severe nephropathy, and urological and hepatobiliary cancers (among others) that are often recurrent and characterized by the prominent mutational fingerprint of AA. However, herbal medicinal products that contain AA continue to be manufactured and marketed worldwide with inadequate regulation, and possible environmental exposure routes receive little attention. As the trade of food and dietary supplements becomes increasingly globalized, we propose that further inaction on curtailing AA exposure will have far-reaching negative effects on the disease trends of AA-associated cancers. Our Review aims to systematically present the historical and current evidence for the mutagenicity and carcinogenicity of AA, and the effect of removing sources of AA exposure on cancer incidence trends. We discuss the persisting challenges of assessing the scale of AA-related carcinogenicity, and the obstacles that must be overcome in curbing AA exposure and preventing associated cancers. Overall, this Review aims to strengthen the case for the implementation of prevention measures against AA's multifaceted, detrimental and potentially fully preventable effects on human cancer development.

Aristolochic acid I exposure decreases oocyte quality

Oocyte quality is a determinant of a successful pregnancy. The final step of oocyte development is oocyte maturation, which is susceptible to environmental exposures. Aristolochic acids (AAs), widely existing in Aristolochia and Asarum plants that have been used in traditional medicine, can result in a smaller ovary and fewer superovulated oocytes after in vivo exposure to mice. However, whether AAs affect oocyte maturation and the underlying mechanism(s) are unclear. In this study, we focused on the effect of Aristolochic acid I (AAI), a major compound of AAs, on the maturation of in vitro cultured mouse oocytes. We showed that AAI exposure significantly decreased oocyte quality, including elevated aneuploidy, accompanied by aberrant chiasma patterns and spindle organization, and decreased first polar body extrusion and fertilization capability. Moreover, embryo development potential was also dramatically decreased. Further analyses revealed that AAI exposure significantly decreased mitochondrial membrane potential and ATP synthesis and increased the level of reactive oxygen species (ROS), implying impaired mitochondrial function. Insufficient ATP supply can cause aberrant spindle assembly and excessive ROS can cause premature loss of sister chromatid cohesion and thus alterations in chiasma patterns. Both aberrant spindles and changed chiasma patterns can contribute to chromosome misalignment and thus aneuploidy. Therefore, AAI exposure decreases oocyte quality probably via impairing mitochondrial function.

Aristolochic acid-containing Chinese herbal medicine and upper urinary tract urothelial carcinoma in Taiwan: a narrative review

PURPOSE

The high incidence of upper urinary tract urothelial carcinoma (UTUC) in Taiwan is largely due to exposure to aristolochic acid (AA), a principal component of Aristolochia-based herbal medicines. Here we systematically review the molecular epidemiology, clinical presentation and biomarkers associated with AA-induced UTUC.

METHODS

This is a narrative review. Medline, Embase, and Web of Science were searched from inception to December 31, 2021. Studies evaluating the association, detection, and clinical characteristics of AA and UTUC were included.

RESULTS

A nationwide database revealed 39% of the Taiwanese population had been exposed to AA-containing herbs between 1997 and 2003. Epidemiological reports revealed AA posed a significantly higher hazard for renal failure and UTUC in herbalists and the general population who ingested AA-containing herbs. The presence of aristolactam-DNA adducts and a distinctive signature mutation, A:T to T:A transversions, located predominantly on the non-transcribed DNA strand, with a strong preference for deoxyadenosine in a consensus sequence (CAG), was observed in many UTUC patients. Clinically, AA-related UTUC patients were characterized by a younger age, female gender, impaired renal function and recurrence of contralateral UTUC. To date, there are no preventive measures, except prophylactic nephrectomy, for subjects at risk of AA nephropathy or AA-related UTUC.

CONCLUSION

AA exposure via Aristolochia-based herbal medicines is a problem throughout Taiwan, resulting in a high incidence of UTUC. Aristolactam-DNA adducts and a distinctive signature mutation, A:T to T:A transversions, can be used as biomarkers to identify AA-related UTUC. AA-related UTUC is associated with a high recurrence rate of contralateral UTUC.

Aristolochic acid I as an emerging biogenic contaminant involved in chronic kidney diseases: A comprehensive review on exposure pathways, environmental health issues and future challenges

Described in the 1950s, Balkan Endemic Nephropathy (BEN) has been recognized as a chronic kidney disease (CKD) with clinical peculiarities and multiple etiological factors. Environmental contaminants - aromatic compounds, mycotoxins and phytotoxins like aristolochic acids (AAs) - polluting food and drinking water sources, were incriminated in BEN, due to their nephrotoxic and carcinogenic properties. The implication of AAs in BEN etiology is currently a highly debated topic due to the fact that they are found within the Aristolochiaceae plants family, used around the globe as traditional medicine and they were also incriminated in Aristolochic Acid Nephropathy (AAN). Exposure pathways have been investigated, but it is unclear to what extent AAs are acting alone or in synergy with other cofactors (environmental, genetics) in triggering kidney damage. Experimental studies strengthen the hypothesis that AAI, the most studied compound in the AAs class, is a significant environmental contaminant and a most important causative factor of BEN. The aim of this review is to compile information about the natural exposure pathways to AAI, via traditional medicinal plants, soil, crop plants, water, food, air. Data that either supports or contradicts the AAI theory concerning BEN etiology was consolidated and available solutions to reduce human exposure were discussed. Because AAI is a phytotoxin with physicochemical properties that allow its transportation in environmental matrices from different types of areas (endemic, nonendemic), and induce CKDs (BEN, AAN) and urinary cancers through bioaccumulation, this review aims to shed a new light on this compound as a biogenic emerging pollutant.

Aristolochic acid and the risk of cancers in patients with type 2 diabetes: Nationwide population-based cohort study

BACKGROUND

Both aristolochic acid (AA) exposure and diabetic can increase risk of certain cancers,whetherAAexposureincreases cancer risk in diabetic patientsisunknown. The purpose of this study was to investigate the association between the use of Chinese herbal products containing AA and the risk of cancer in diabetic patients.

METHODS

A cohort study was conducted using the National Health Insurance Research Database in Taiwan. Patients older than 18 years who were diagnosed with diabetes between 1997 and 2010 were enrolled in our cohort. The use of Chinese herbal products containing AA was recorded from the beginning of 1997 until the ban of herbs containing AA in November 2003. Patients were individually tracked to identify cancer incidence between 1997 and 2013. Only patients who visited traditional Chinese medicine clinics between 1997 and 1 year before the end of follow-up were included in the cohort to ensure comparability. Cox proportional hazards regression was used to calculate the hazard ratio for the association between the use of Chinese herbal products containing AA and the occurrence of cancer.

RESULTS

Among the 430 377 male and 431 956 female patients with diabetes enrolled in our cohort, 37 554 and 31 535 cancer diagnoses were recorded during the study period, respectively. The use of AA-containing herbal products was associated with a significantly higher risk of liver, colorectum, kidney, bladder, prostate, pelvis, and ureter cancer in a dose-dependent manner. An increased risk of extrahepatic bile duct cancer in women was also associated with AA exposure at doses of more than 500 mg.

CONCLUSIONS

Association between AA exposure and the risk of some cancers were found in this study. AA exposure might increase risk of kidney,bladder,pelvis, ureter,liver,colorectum,andprostatecancer in all patientsandextrahepatic bile duct cancerin women.

Rare Occurrence of Aristolochic Acid Mutational Signatures in Oro-Gastrointestinal Tract Cancers

BACKGROUND

Aristolochic acids (AAs) are potent mutagens commonly found in herbal plant-based remedies widely used throughout Asian countries.

PATIENTS AND METHODS

To understand whether AA is involved in the tumorigenesis of the oro-gastrointestinal tract, we used whole-exome sequencing to profile 54 cases of four distinct types of oro-gastrointestinal tract cancer (OGITC) from Taiwan.

RESULTS

A diverse landscape of mutational signatures including those from DNA mismatch repair and reactive oxygen species was observed. APOBEC mutational signatures were observed in 60% of oral squamous cell carcinomas. Only one sample harbored AA mutational signatures, contradictory to prior reports of cancers from Taiwan. The metabolism of AA in the liver and urinary tract, transient exposure time, and high cell turnover rates at OGITC sites may explain our findings.

CONCLUSION

AA signatures in OGITCs are rare and unlikely to be a major contributing factor in oro-gastrointestinal tract tumorigenesis.

A DNA adductome analysis revealed a reduction in the global level of C5-hydroxymethyl-2'-deoxycytidine in the non-tumoral upper urinary tract mucosa of urothelial carcinoma patients

Background

DNA adducts, covalent modifications to DNA due to exposure to specific carcinogens, cause the mispairing of DNA bases, which ultimately results in DNA mutations. DNA methylation in the promoter region, another type of DNA base modification, alters the DNA transcription process, and has been implicated in carcinogenesis in humans due to the down-regulation of tumor suppressor genes. Difficulties are associated with demonstrating the existence of DNA adducts or chemically modified bases in the human urological system. Apart from aristolochic acid-DNA adducts, which cause urothelial carcinoma and endemic nephropathy in a particular geographical area (Balkan), limited information is currently available on DNA adduct profiles in renal cell carcinoma and upper urinary tract urothelial carcinoma, including renal pelvic cancer and ureteral cancer.

Method

To elucidate the significance of DNA adducts in carcinogenesis in the urothelial system, we investigated 53 DNA adducts in the non-tumoral renal parenchyma and non-tumoral renal pelvis of patients with renal cell carcinoma, upper urinary tract urothelial carcinoma, and other diseases using liquid chromatography coupled with tandem mass spectrometry. A comparative analysis of tissue types, the status of malignancy, and clinical characteristics, including lifestyle factors, was performed.

Results

C5-Methyl-2′-deoxycytidine, C5-hydroxymethyl-2′-deoxycytidine (5hmdC), C5-formyl-2′-deoxycytidine, 2′-deoxyinosine, C8-oxo-2′-deoxyadenosine, and C8-oxo-2′-deoxyguanosine (8-OHdG) were detected in the renal parenchyma and renal pelvis. 8-OHdG was more frequently detected in the renal pelvis than in the renal cortex and medulla (p = 0.048 and p = 0.038, respectively). 5hmdC levels were significantly lower in the renal pelvis of urothelial carcinoma patients (n = 10) than in the urothelium of patients without urothelial carcinoma (n = 15) (p = 0.010). Regarding 5hmdC levels in the renal cortex and medulla, Spearman’s rank correlation test revealed a negative correlation between age and 5hmdC levels (r = − 0.46, p = 0.018 and r = − 0.45, p = 0.042, respectively).

Conclusions

The present results revealed a reduction of 5hmdC levels in the non-tumoral urinary tract mucosa of patients with upper urinary tract urothelial carcinoma. Therefore, the urothelial cell epithelia of patients with upper urinary tract cancer, even in non-cancerous areas, may be predisposed to urothelial cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41021-021-00228-9.

Aristolochic acid I promoted clonal expansion but did not induce hepatocellular carcinoma in adult rats

Aristolochic acid I (AAI) is a well-known nephrotoxic carcinogen, which is currently reported to be also associated with hepatocellular carcinoma (HCC). Whether AAI is a direct hepatocarcinogen remains controversial. In this study we investigated the association between AAI exposure and HCC in adult rats using a sensitive rat liver bioassay with several cofactors. Formation of glutathione S-transferase placental form-positive (GST-P+) foci was used as the marker for preneoplastic lesions/clonal expansion. We first conducted a medium-term (8 weeks) study to investigate whether AAI had any tumor-initiating or -promoting activity. Then a long-term (52 weeks) study was conducted to determine whether AAI can directly induce HCC. We showed that oral administration of single dose of AAI (20, 50, or 100 mg/kg) in combination with partial hepatectomy (PH) to stimulate liver proliferation did not induce typical GST-P+ foci in liver. In the 8-week study, only high dose of AAI (10 mg · kg-1 · d-1, 5 days a week for 6 weeks) in combination with PH significantly increased the number and area of GST-P+ foci initiated by diethylnitrosamine (DEN) in liver. Similarly, only high dose of AAI (10 mg· kg-1· d-1, 5 days a week for 52 weeks) in combination with PH significantly increased the number and area of hepatic GST-P+ foci in the 52-week study. No any nodules or HCC were observed in liver of any AAI-treated groups. In contrast, long-term administration of AAI (0.1, 1, 10 mg· kg-1· d-1) time- and dose-dependently caused death due to the occurrence of cancers in the forestomach, intestine, and/or kidney. Besides, AAI-DNA adducts accumulated in the forestomach, kidney, and liver in a time- and dose-dependent manner. Taken together, AAI promotes clonal expansion only in the high-dose group but did not induce any nodules or HCC in liver of adult rats till their deaths caused by cancers developed in the forestomach, intestine, and/or kidney. Findings from our animal studies will pave the way for further large-scale epidemiological investigation of the associations between AA and HCC.

Co-Exposure to Aristolochic Acids I and II Increases DNA Adduct Formation Responsible for Aristolochic Acid I-Mediated Carcinogenicity in Rats

The plant extract aristolochic acid (AA), containing aristolochic acids I (AAI) and II (AAII) as major components, causes aristolochic acid nephropathy (AAN) and Balkan endemic nephropathy (BEN), unique renal diseases associated with upper urothelial cancer. Recently (Chemical Research in Toxicology 33(11), 2804–2818, 2020), we showed that the in vivo metabolism of AAI and AAII in Wistar rats is influenced by their co-exposure (i.e., AAI/AAII mixture). Using the same rat model, we investigated how exposure to the AAI/AAII mixture can influence AAI and AAII DNA adduct formation (i.e., AA-mediated genotoxicity). Using ³²P-postlabelling, we found that AA-DNA adduct formation was increased in the livers and kidneys of rats treated with AAI/AAII mixture compared to rats treated with AAI or AAII alone. Measuring the activity of enzymes involved in AA metabolism, we showed that enhanced AA-DNA adduct formation might be caused partially by both decreased AAI detoxification as a result of hepatic CYP2C11 inhibition during treatment with AAI/AAII mixture and by hepatic or renal NQO1 induction, the key enzyme predominantly activating AA to DNA adducts. Moreover, our results indicate that AAII might act as an inhibitor of AAI detoxification in vivo. Consequently, higher amounts of AAI might remain in liver and kidney tissues, which can be reductively activated, resulting in enhanced AAI DNA adduct formation. Collectively, these results indicate that AAII present in the plant extract AA enhances the genotoxic properties of AAI (i.e., AAI DNA adduct formation). As patients suffering from AAN and BEN are always exposed to the plant extract (i.e., AAI/AAII mixture), our findings are crucial to better understanding host factors critical for AAN- and BEN-associated urothelial malignancy.

Aristolochic acid-associated urinary tract cancers: an updated meta-analysis of risk and oncologic outcomes after surgery and systematic review of molecular alterations observed in human studies

BACKGROUND

The risk of primary aristolochic acid (AA)-associated urothelial carcinoma (AA-UC) has been summarized by a 2013-published meta-analysis. Given that additional evidence has been continuously reported by original studies, an updated meta-analysis is needed. Meanwhile, to complete the whole picture, a systematic review of molecular alterations observed in AA-urinary tract cancers (AA-UTC) was also performed.

METHODS

We searched PubMed, Embase and four Chinese databases up to October 2020. Observational studies comparing risk or oncologic outcomes of UTC between patients with and without AA exposure were eligible for systematic review and meta-analysis. Studies investigating molecular alterations in AA-UTC using human tissue samples were eligible for systematic review.

RESULTS

In total, 38 and 20 studies were included in the systematic review and meta-analysis, respectively. Exposure to AA led to an overall increased risks of primary UTC [UC and renal cell carcinoma (RCC)] (OR 6.085, 95% CI 3.045-12.160) and postoperatively recurrent UC (RR 1.831, 95% CI 1.528-2.194). Subgroup analysis of postoperative primary AA-upper tract UC (AA-UTUC) showed increased risks of bladder recurrence (adjusted RR 1.949, 95% CI 1.462-2.597) and contralateral UTUC recurrence (crude RR 3.760, 95% CI 2.225-6.353), worse overall survival (adjusted HR 2.025, 95% CI 1.432-2.865) and worse disease-specific survival (adjusted HR 3.061, 95% CI 1.190-7.872), but no effect on cancer-specific survival (adjusted HR 0.772, 95% CI 0.269-2.215). High mutation load with AA mutational signature presenting largely in the putative driver genes was observed in AA-UTUC. In contrast, AA mutational signature is rarely found in the mutated RCC driver genes and the mutation load in AA-RCC is low. Therefore, AA has different roles in the genesis of UTUC and RCC.

CONCLUSIONS

Implementing effective strategies to completely protect people from exposure to AA is urgently needed. Additionally, more effort should be made in identifying the precise carcinogenic mechanisms of AA to determine the future treatment strategies.

PLAIN LANGUAGE SUMMARY

Risk, recurrence and survival outcomes after surgery and molecular changes possibly involved in the genesis of aristolochic acid-associated urinary tract cancers Background: The association between aristolochic acid (AA) and primary urothelial carcinoma (UC) has been summarized by a 2013-published meta-analysis. Given that additional evidence has been reported in the past 7 years, an updated meta-analysis is needed. Meanwhile, to complete the whole picture, a systematic review of molecular changes possibly involved in AA-mediated urinary tract carcinogenesis was also performed. Methods: We searched PubMed, Embase and four Chinese databases for human studies up to October 2020. Studies comparing the risk of urinary tract cancer (UTC) between patients with and without AA exposure and studies investigating the molecular changes in AA-associated UTC (AA-UTC) using human tissue samples were eligible for inclusion. Thirty-eight studies were finally included. Results: The results showed that exposure to AA was associated with a 6-fold increased risk of primary UTC (UC and renal cell carcinoma, RCC) and a 1.8-fold increased risk of postoperatively recurrent UC. After studies reporting primary AA-upper tract UC (AA-UTUC) were analyzed, a 1.9-fold increased risk of bladder recurrence and a 3.8-fold increased risk of contralateral UTUC recurrence was observed. Additionally, exposure to AA worsened the postoperative survival of patients with UTUC by a 2-fold increased risk of overall death and a 3-fold increased risk of death from other diseases and recurrences. However, there was no effect on death due to cancer. Lastly, AA seemed to play different roles in the etiology of UTUC and RCC based on the observations of different mutation loads and different distributions of AA-induced mutations in AA-UTUC and AA-RCC samples. Conclusions: Implementing effective strategies to completely protect people from exposure to AA is urgently needed. Moreover, more effort should be made in identifying the precise carcinogenic mechanisms of AA-UTC to determine the future treatment strategies.

Rad18 mediates specific mutational signatures and shapes the genomic landscape of carcinogen-induced tumors in vivo

The E3 ubiquitin ligase Rad18 promotes a damage-tolerant and error-prone mode of DNA replication termed trans-lesion synthesis that is pathologically activated in cancer. However, the impact of vertebrate Rad18 on cancer genomes is not known. To determine how Rad18 affects mutagenesis in vivo, we have developed and implemented a novel computational pipeline to analyze genomes of carcinogen (7, 12-Dimethylbenz[a]anthracene, DMBA)-induced skin tumors from Rad18^+/+ and Rad18^{- / -} mice. We show that Rad18 mediates specific mutational signatures characterized by high levels of A(T)>T(A) single nucleotide variations (SNVs). In Rad18^{- /-} tumors, an alternative mutation pattern arises, which is characterized by increased numbers of deletions >4 bp. Comparison with annotated human mutational signatures shows that COSMIC signature 22 predominates in Rad18^+/+ tumors whereas Rad18^{- / -} tumors are characterized by increased contribution of COSMIC signature 3 (a hallmark of BRCA-mutant tumors). Analysis of The Cancer Genome Atlas shows that RAD18 expression is strongly associated with high SNV burdens, suggesting RAD18 also promotes mutagenesis in human cancers. Taken together, our results show Rad18 promotes mutagenesis in vivo, modulates DNA repair pathway choice in neoplastic cells, and mediates specific mutational signatures that are present in human tumors.

Aristolochic acid and its effect on different cancers in uro-oncology

PURPOSE OF REVIEW

To acquaint urologists with aristolochic acid nephropathy, an iatrogenic disease that poses a distinct threat to global public health. In China alone, 100 million people may currently be at risk. We illustrate the power of molecular epidemiology in establishing the cause of this disease.

RECENT FINDINGS

Molecular epidemiologic approaches and novel mechanistic information established a causative linkage between exposure to aristolochic acid and urothelial carcinomas of the bladder and upper urinary tract. Noninvasive tests are available that detect urothelial cancers through the genetic analysis of urinary DNA. Combined with cytology, some of these tests can detect 95% of patients at risk of developing bladder and/or upper urothelial tract cancer. Robust biomarkers, including DNA-adduct and mutational signature analysis, unequivocally identify aristolochic acid-induced tumours. The high mutational load associated with aristolochic acid-induced tumours renders them candidates for immune-checkpoint therapy.

SUMMARY

Guided by recent developments that facilitate early detection of urothelial cancers, the morbidity and mortality associated with aristolochic acid-induced bladder and upper tract urothelial carcinomas may be substantially reduced. The molecular epidemiology tools that define aristolochic acid-induced tumours may be applicable to other studies assessing potential environmental carcinogens.

Applying Tobacco, Environmental, and Dietary-Related Biomarkers to Understand Cancer Etiology and Evaluate Prevention Strategies

Many human cancers are caused by environmental and lifestyle factors. Biomarkers of exposure and risk developed by our team have provided critical data on internal exposure to toxic and genotoxic chemicals and their connection to cancer in humans. This review highlights our research using biomarkers to identify key factors influencing cancer risk as well as their application to assess the effectiveness of exposure intervention and chemoprevention protocols. The use of these biomarkers to understand individual susceptibility to the harmful effects of tobacco products is a powerful example of the value of this type of research and has provided key data confirming the link between tobacco smoke exposure and cancer risk. Furthermore, this information has led to policy changes that have reduced tobacco use and consequently, the tobacco-related cancer burden. Recent technological advances in mass spectrometry led to the ability to detect DNA damage in human tissues as well as the development of adductomic approaches. These new methods allowed for the detection of DNA adducts in tissues from patients with cancer, providing key evidence that exposure to carcinogens leads to DNA damage in the target tissue. These advances will provide valuable insights into the etiologic causes of cancer that are not tobacco-related.See all articles in this CEBP Focus section, "Environmental Carcinogenesis: Pathways to Prevention."

Integration of medicinal plants into the traditional system of medicine for the treatment of cancer in Sokoto State, Nigeria

This study was designed to explore and record various medicinal plants integrated into the traditional system of medicine for the treatment of cancer. The traditional system of medicine is a routine practiced among the indigenous ethnic groups of Sokoto state. A semi-structured questionnaire was designed and used for data collection around the selected Local Government Areas. A substantial number of plant species were identified, recorded, and collected for preservation. Data collected for each specie was analysed to assess its frequent use among the medicinal plants. A total of 67 species belonging to 31 families have been identified and recorded. Out of the 473 frequency of citation (FC), Acacia nilotica was the most frequently cited specie (32 FC, 64% FC, 0.6 RFC), followed by Guiera senegalensis (27 FC, 54% FC, 0.5 RFC), Erythrina sigmoidea (17 FC, 34% FC, 0.3 RFC), and subsequently Combretum camporum (15 FC, 30% FC, 0.3 RFC). The most common parts of the plants used include the barks (55.2%), the roots (53.2%), and the leaves (41.8%). Additionally, decoction (74.6%), powdered form (49.3%), and maceration (46.3%) are the most frequently used mode of preparation. The historical knowledge of a traditional system of medicine practiced by the native traditional healers of Sokoto for the treatment of cancer has been documented. The present study further provides a baseline for future pharmacological investigations into the beneficial effects of such medicinal plants for the treatment of cancer.

Plant-Derived Nutraceuticals and Immune System Modulation: An Evidence-Based Overview

Immunomodulators are agents able to affect the immune system, by boosting the immune defences to improve the body reaction against infectious or exogenous injuries, or suppressing the abnormal immune response occurring in immune disorders. Moreover, immunoadjuvants can support immune system acting on nonimmune targets, thus improving the immune response. The modulation of inflammatory pathways and microbiome can also contribute to control the immune function. Some plant-based nutraceuticals have been studied as possible immunomodulating agents due to their multiple and pleiotropic effects. Being usually more tolerable than pharmacological treatments, their adjuvant contribution is approached as a desirable nutraceutical strategy. In the present review, the up to date knowledge about the immunomodulating properties of polysaccharides, fatty acids and labdane diterpenes have been analyzed, in order to give scientific basic and clinical evidence to support their practical use. Since promising evidence in preclinical studies, limited and sometimes confusing results have been highlighted in clinical trials, likely due to low methodological quality and lacking standardization. More investigations of high quality and specificity are required to describe in depth the usefulness of these plant-derived nutraceuticals in the immune system modulation, for health promoting and disease preventing purposes.

Clinicopathologic characteristics and prognosis of upper tract urothelial carcinoma complicated with aristolochic acid nephropathy after radical nephroureterectomy

Background

The purpose of this study was to identify the clinicopathologic characteristics and prognosis of upper tract urothelial carcinoma (UTUC) patients complicated with aristolochic acid nephropathy(AAN) after radical nephroureterectomy (RNU).

Methods

The clinical data of 42 UTUC patients with AAN (AAN group) and 238 UTUC patients without AAN (Non-AAN group) were retrospectively reviewed. All patients received a RNU with excision of bladder cuff. Demographic and clinical data, including preoperative indexes, intraoperative indexes and surgical outcomes were compared.

Results

There were no significant differences in age, tumor location, surgery approach, tumor pathologic grade, stage, the mean operative time and estimated blood loss between the two groups (all p > 0.05). There were more female patients in the AAN group (p < 0.001), and 57.1% were high grade tumors. The AAN group showed a higher complications rate (p = 0.003). The median follow-up time was 43.2 months. The AAN group showed a worse estimated 5-year overall survival rate (35.1% vs. 63.0%, p = 0.014), however, no significant difference was found between the two groups with regard to disease specific survival (63.5% vs. 81.5%, p = 0.091). Multivariate binary logistic regression analysis showed that AAN was an independent factor related with overall and disease specific survival. 38.9% of all patients experienced any types of recurrence, and the estimated 5-year recurrence-free survival rate was lower in the AAN group (37.1% vs. 63.7%, p = 0.001). In the comparison of subgroups stratified by recurrence type, the AAN group had a higher intravesical (p = 0.030) and contralateral recurrence rate (p = 0.040).

Conclusion

UTUC with AAN occurred more frequently in female patients who were more likely to develop high-grade tumors. However, these patients showed a worse overall survival and a lower recurrence-free survival rate than the other patients. AA-related UTUC might be associate with an increased risk of intravesical and contralateral recurrence after RUN.

Toward clinical understanding of aristolochic acid upper-tract urothelial carcinoma

A cluster of patients poisoned by herbal medicine in the 1990s revealed that aristolochic acid (AA) causes kidney failure and upper tract urothelial carcinoma (UTUC). Recent research demonstrated that this was not an isolated incident; on the contrary, AA exposure is widespread in East Asia. This editorial highlights research by Lu and colleagues that investigates clinical characteristics of AA and non-AA UTUCs from 90 patients in Beijing based on the AA mutational signature. The study also detected AA mutations in non-tumor tissue of AA exposed patients and showed that AA mutations can be detected in urine, which might form the basis for non-invasive tests for AA exposure.

DNA adducts: Formation, biological effects, and new biospecimens for mass spectrometric measurements in humans

Hazardous chemicals in the environment and diet or their electrophilic metabolites can form adducts with genomic DNA, which can lead to mutations and the initiation of cancer. In addition, reactive intermediates can be generated in the body through oxidative stress and damage the genome. The identification and measurement of DNA adducts are required for understanding exposure and the causal role of a genotoxic chemical in cancer risk. Over the past three decades, 32 P-postlabeling, immunoassays, gas chromatography/mass spectrometry, and liquid chromatography/mass spectrometry (LC/MS) methods have been established to assess exposures to chemicals through measurements of DNA adducts. It is now possible to measure some DNA adducts in human biopsy samples, by LC/MS, with as little as several milligrams of tissue. In this review article, we highlight the formation and biological effects of DNA adducts, and highlight our advances in human biomonitoring by mass spectrometric analysis of formalin-fixed paraffin-embedded tissues, untapped biospecimens for carcinogen DNA adduct biomarker research.

The Mutational Features of Aristolochic Acid-Induced Mouse and Human Liver Cancers

BACKGROUND AND AIMS

Aristolochic acid (AA) exposure has been statistically associated with human liver cancers. However, direct evidence of AA exposure-induced liver cancer is absent. This study aims to establish a direct causal relationship between AA exposure and liver cancers based on a mouse model and then explores the AA-mediated genomic alterations that could be implicated in human cancers with AA-associated mutational signature.

APPROACH AND RESULTS

We subjected mice, including phosphatase and tensin homolog (Pten)-deficient ones, to aristolochic acid I (AAI) alone or a combination of AAI and CCl₄ . Significantly, AAI exposure induced mouse liver cancers, including hepatocellular carcinoma (HCC) and combined HCC and intrahepatic cholangiocarcinoma, in a dose-dependent manner. Moreover, AAI exposure also enhanced tumorigenesis in these CCl₄ -treated or Pten-deficient mice. AAI led to DNA damage and AAI-DNA adduct that could initiate liver cancers through characteristic adenine-to-thymine transversions, as indicated by comprehensive genomic analysis, which revealed recurrent mutations in Harvey rat sarcoma virus oncogene. Interestingly, an AA-associated mutational signature was mainly implicated in human liver cancers, especially from China. Moreover, we detected the AAI-DNA adduct in 25.8% (16/62) of paratumor liver tissues from randomly selected Chinese patients with HCC. Furthermore, based on phylogenetic analysis, the characteristic mutations were found in the initiating malignant clones in the AA-implicated mouse and human liver cancers where the mutations of tumor protein p53 and Janus kinase 1 were prone to be significantly enriched in the AA-affected human tumors.

CONCLUSIONS

This study provides evidence for AA-induced liver cancer with the featured mutational processes during malignant clonal evolution, laying a solid foundation for the prevention and diagnosis of AA-associated human cancers, especially liver cancers.

Integrative genomic study of Chinese clear cell renal cell carcinoma reveals features associated with thrombus

Clear cell renal cell carcinoma (ccRCC) is a heterogeneous disease with features that vary by ethnicity. A systematic characterization of the genomic landscape of Chinese ccRCC is lacking, and features of ccRCC associated with tumor thrombus (ccRCC-TT) remain poorly understood. Here, we applied whole-exome sequencing on 110 normal-tumor pairs and 42 normal-tumor-thrombus triples, and transcriptome sequencing on 61 tumor-normal pairs and 30 primary-thrombus pairs from 152 Chinese patients with ccRCC. Our analysis reveals that a mutational signature associated with aristolochic acid (AA) exposure is widespread in Chinese ccRCC. Tumors from patients with ccRCC-TT show a higher mutational burden and genomic instability; in addition, mutations in BAP1 and SETD2 are highly enriched in patients with ccRCC-TT. Moreover, patients with/without TT show distinct molecular characteristics. We reported the integrative genomic sequencing of Chinese ccRCC and identified the features associated with tumor thrombus, which may facilitate ccRCC diagnosis, prognosis and treatment.

The genomic heterogeneity of clear cell renal cell carcinoma (ccRCC) across populations is poorly understood. Here, the authors analyse a cohort of Chinese ccRCC cases revealing a mutational signature associated with aristolochic acid exposure, and higher mutational burden and enrichment for BAP1 and SETD2 mutations in ccRCC cases associated with tumor thrombus.

Occurrence and Environmental Stability of Aristolochic Acids in Groundwater Collected from Serbia: Links to Human Exposure and Balkan Endemic Nephropathy

Aristolochic acids (AAs) have been known as potent nephrotoxins since the use of AA-containing herbal medicines was linked with a series of sporadic renal fibrotic nephropathy cases, and yet an estimated 100 million people worldwide are still at risk today because of continued use of similar medicines. However, a similar nephropathic condition is endemic in the rural Balkan regions (e.g., Serbian farming villages) and AAs were again found to be the causative agents. In the case of this Balkan endemic nephropathy, AAs were found to have originated from a widespread local weed Aristolochia clematitis L. In this study, we tested the hypothesis that AAs released from decomposition of A. clematitis were also being leached into groundwater, thus polluting the drinking water of local residents. We initiated the study by developing a dispersive solid-phase extraction-based sample preparation method for water samples suspected of AA contamination. The validated method was then coupled with a liquid chromatography-tandem mass spectrometric method to measure AAs in groundwater samples collected from Serbia. Our study revealed for the first time that groundwater in Serbia is extensively contaminated with AA-I, at ng/L levels. Results also showed that AAs are long-lived water contaminants, with no observable concentration changes over a 2-month period of sample storage.

Biotransformation and Toxicities of Aristolochic Acids

Environmental and iatrogenic exposures contribute significantly to human diseases, including cancer. The list of known human carcinogens has recently been extended by the addition of aristolochic acids (AAs). AAs occur primarily in Aristolochia herbs, which are used extensively in folk medicines, including Traditional Chinese Medicine. Ingestion of AAs results in chronic renal disease and cancer. Despite importation bans imposed by certain countries, herbal remedies containing AAs are readily available for purchase through the internet. With recent advancements in mass spectrometry, next generation sequencing, and the development of integrated organs-on-chips, our knowledge of cancers associated with AA exposure, and of the mechanisms involved in AA toxicities, has significantly improved. DNA adduction plays a central role in AA-induced cancers; however, significant gaps remain in our knowledge as to how cellular enzymes promote activation of AAs and how the reactive species selectively bind to DNA and kidney proteins. In this review, I describe pathways for AAs biotransformation, adduction, and mutagenesis, emphasizing novel methods and ideas contributing to our present understanding of AA toxicities in humans.

The Impact of p53 on Aristolochic Acid I-Induced Gene Expression In Vivo

Exposure to aristolochic acid (AA) is linked to kidney disease and urothelial cancer in humans. The major carcinogenic component of the AA plant extract is aristolochic acid I (AAI). The tumour suppressor p53 is frequently mutated in AA-induced tumours. We previously showed that p53 protects from AAI-induced renal proximal tubular injury, but the underlying mechanism(s) involved remain to be further explored. In the present study, we investigated the impact of p53 on AAI-induced gene expression by treating Trp53(+/+), Trp53(+/-), and Trp53(-/-) mice with 3.5 mg/kg body weight (bw) AAI daily for six days. The Clariom™ S Assay microarray was used to elucidate gene expression profiles in mouse kidneys after AAI treatment. Analyses in Qlucore Omics Explorer showed that gene expression in AAI-exposed kidneys is treatment-dependent. However, gene expression profiles did not segregate in a clear-cut manner according to Trp53 genotype, hence further investigations were performed by pathway analysis with MetaCore™. Several pathways were significantly altered to varying degrees for AAI-exposed kidneys. Apoptotic pathways were modulated in Trp53(+/+) kidneys; whereas oncogenic and pro-survival pathways were significantly altered for Trp53(+/-) and Trp53(-/-) kidneys, respectively. Alterations of biological processes by AAI in mouse kidneys could explain the mechanisms by which p53 protects from or p53 loss drives AAI-induced renal injury in vivo.

Bioactivation mechanisms of N-hydroxyaristolactams: Nitroreduction metabolites of aristolochic acids

Aristolochic acids (AAs) are human nephrotoxins and carcinogens found in concoctions of Aristolochia plants used in traditional medicinal practices worldwide. Genotoxicity of AAs is associated with the formation of active species catalyzed by metabolic enzymes, the full repertoire of which is unknown. Recently, we provided evidence that sulfonation is important for bioactivation of AAs. Here, we employ Salmonella typhimurium umu tester strains expressing human N-acetyltransferases (NATs) and sulfotransferases (SULTs), to study the role of conjugation reactions in the genotoxicities of N-hydroxyaristolactams (AL-I-NOH and AL-II-NOH), metabolites of AA-I and AA-II. Both N-hydroxyaristolactams show stronger genotoxic effects in umu strains expressing human NAT1 and NAT2, than in the parent strain. Additionally, AL-I-NOH displays increased genotoxicity in strains expressing human SULT1A1 and SULT1A2, whereas AL-II-NOH shows enhanced genotoxicity in SULT1A1/2 and SULT1A3 strains. 2,6-Dichloro-4-nitrophenol, SULTs inhibitor, reduced umuC gene expression induced by N-hydroxyaristolactams in SULT1A2 strain. N-hydroxyaristolactams are also mutagenic in parent strains, suggesting that an additional mechanism(s) may contribute to their genotoxicities. Accordingly, using putative SULT substrates and inhibitors, we found that cytosols obtained from human kidney HK-2 cells activate N-hydroxyaristolactams in aristolactam-DNA adducts with the limited involvement of SULTs. Removal of low-molecular-weight reactants in the 3.5-10 kDa range inhibits the formation of aristolactam-DNA by 500-fold, which could not be prevented by the addition of cofactors for SULTs and NATs. In conclusion, our results demonstrate that the genotoxicities of N-hydroxyaristolactams depend on the cell type and involve not only sulfonation but also N,O-acetyltransfer and an additional yet unknown mechanism(s). Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

Health risk associated with the oral consumption of "Chiniy-tref", a traditional medicinal preparation used in Martinique (French West Indies): Qualitative and quantitative analyses of aristolochic acids contained therein

"Chiniy-tref" (CT) is a traditional preparation used in folk medicine in Martinique Island (French West Indies) that is nowadays mainly taken orally to prevent or act against any "manifestation of evil". CT is easily prepared at home by macerating larvae of the endemic swallowtail Battus polydamas (ssp.) cebriones (Dalman, 1823), sometimes accompanied by a leaf of its host-plant Aristolochia trilobata L., in commercial rum. We have previously reported the detection of nephrotoxic and carcinogenic aristolochic acids (AAs) I and II in CT, leading the Regional Health Agency (ARS) of Martinique to issue an alert regarding the potential risks associated with its consumption in 2015. In order to complete the toxicity risk assessment for oral consumption of CT, a full qualitative analysis of AAs and their analogues (AAAs) was performed, as well as a quantitative determination of the major AAs, namely AAs I and II. The phytochemical profiling of AAAs present in CT, that also corresponds to that of B. polydamas cebriones larvae feeding on A. trilobata, has been established for the first time by ultra-high performance liquid chromatography/electrospray ionization quadrupole time of-flight tandem mass spectrometry. AAs I and II were quantified in a small panel of tinctures by using a validated UHPLC/UV method, allowing us to estimate the probable daily intakes of these toxins by CT consumers. The results proved the existence of a real risk of renal toxicity and carcinogenicity associated with the chronic oral consumption of CT in Martinique, and more generally of similar "snake bottles" throughout the Caribbean.

The impact of p53 on aristolochic acid I-induced nephrotoxicity and DNA damage in vivo and in vitro

Exposure to aristolochic acid (AA) is associated with human nephropathy and urothelial cancer. The tumour suppressor TP53 is a critical gene in carcinogenesis and frequently mutated in AA-induced urothelial tumours. We investigated the impact of p53 on AAI-induced nephrotoxicity and DNA damage in vivo by treating Trp53(+/+), Trp53(+/-) and Trp53(-/-) mice with 3.5 mg/kg body weight (bw) AAI daily for 2 or 6 days. Renal histopathology showed a gradient of intensity in proximal tubular injury from Trp53(+/+) to Trp53(-/-) mice, especially after 6 days. The observed renal injury was supported by nuclear magnetic resonance (NMR)-based metabonomic measurements, where a consistent Trp53 genotype-dependent trend was observed for urinary metabolites that indicate aminoaciduria (i.e. alanine), lactic aciduria (i.e. lactate) and glycosuria (i.e. glucose). However, Trp53 genotype had no impact on AAI-DNA adduct levels, as measured by 32P-postlabelling, in either target (kidney and bladder) or non-target (liver) tissues, indicating that the underlying mechanisms of p53-related AAI-induced nephrotoxicity cannot be explained by differences in AAI genotoxicity. Performing gas chromatography-mass spectrometry (GC-MS) on kidney tissues showed metabolic pathways affected by AAI treatment, but again Trp53 status did not clearly impact on such metabolic profiles. We also cultured primary mouse embryonic fibroblasts (MEFs) derived from Trp53(+/+), Trp53(+/-) and Trp53(-/-) mice and exposed them to AAI in vitro (50 µM for up to 48 h). We found that Trp53 genotype impacted on the expression of NAD(P)H:quinone oxidoreductase (Nqo1), a key enzyme involved in AAI bioactivation. Nqo1 induction was highest in Trp53(+/+) MEFs and lowest in Trp53(-/-) MEFs; and it correlated with AAI-DNA adduct formation, with lowest adduct levels being observed in AAI-exposed Trp53(-/-) MEFs. Overall, our results clearly demonstrate that p53 status impacts on AAI-induced renal injury, but the underlying mechanism(s) involved remain to be further explored. Despite the impact of p53 on AAI bioactivation and DNA damage in vitro, such effects were not observed in vivo.

Toxicity of traditional Chinese medicine herbal and mineral products

Traditional Chinese medicine (TCM) has been used to treat numerous kinds of diseases for more than 2000 years in eastern Asian countries. A portion of the TCM herbal and mineral products are believed to be toxic according to modern standards, and are still widely prescribed in the clinic. However, some TCM products considered to be non-toxic or low-toxic have been reported to possess significant toxicological effects on different organs in both animal and human models. In this review, we define the term "toxic" in TCM, and then we summarize the advances in pharmacology and toxicology research of Toxic Traditional Chinese Medicine (TTCM), including Chinese aconite (Fu Zi), Arsenic Trioxide, Tripterygium wilfordii Hook f. (Thunder God Vine), herbal drugs derived from plants in the Aristolochiaceae Juss. family (Ma Dou Ling), and other TCM products. Finally, the compatibility art of TCM and modern pharmaceutical approaches to manage undesired toxicity of TTCM is discussed. Promoting pharmacology and toxicology studies of TTCM and non-toxic TCM is critical for the further development and safety of TCM in clinical practice.

Herbal Medicine Containing Aristolochic Acid and the Risk of Primary Liver Cancer in Patients with Hepatitis C Virus Infection

BACKGROUND

We investigated the association between taking herbal medicine (HM) containing aristolochic acid (AA) and the risk of primary liver cancer (PLC) among patients with hepatitis C virus (HCV) infection.

METHODS

This is a prospective study for the long-term follow-up of a nationwide population-based cohort of patients ages 18 years or older diagnosed with HCV infection during 1997 to 2010. A total of 223,467 HCV-infected patients were identified using the National Health Insurance Research Database in Taiwan. The use of HM containing AA was evaluated among patients who had visited traditional Chinese medicine clinics beginning from 1997 to 1 year prior to the diagnosis of PLC or dates censored (2003). We tracked each individual patient from 1997 to 2013 to identify incident cases of PLC since 1999.

RESULTS

During the follow-up period of 3,052,132 person-years, we identified 25,502 PLC cases; this corresponded to an overall incidence rate of 835.5 PLCs per 100,000 person-years. The adjusted HRs were 1.21 [95% confidence interval (CI), 1.18-1.24], 1.48 (95% CI, 1.37-1.59), 1.50 (95% CI, 1.34-1.68), and 1.88 (95% CI, 1.61-2.19) for estimated AA usage groups: 1 to 250, 251 to 500, 501 to 1,000, and more than 1,000 mg, respectively, relative to no AA exposure (reference group).

CONCLUSIONS

The current findings suggest that among HCV-positive patients, increasing exposure to AA poses an increased risk of acquiring PLC.

IMPACT

AA may increase the risk of PLC in HCV-positive populations.

Systematic Overview of Aristolochic Acids: Nephrotoxicity, Carcinogenicity, and Underlying Mechanisms

Aristolochic acids (AAs) are a group of toxins commonly present in the plants of genus Aristolochia and Asarum, which are spread all over the world. Since the 1990s, AA-induced nephropathy (AAN) and upper tract urothelial carcinoma (UTUC) have been reported in many countries. The underlying mechanisms of AAN and AA-induced UTUC have been extensively investigated. AA-derived DNA adducts are recognized as specific biomarkers of AA exposure, and a mutational signature predominantly characterized by A→T transversions has been detected in AA-induced UTUC tumor tissues. In addition, various enzymes and organic anion transporters are involved in AA-induced adverse reactions. The progressive lesions and mutational events initiated by AAs are irreversible, and no effective therapeutic regimen for AAN and AA-induced UTUC has been established until now. Because of several warnings on the toxic effects of AAs by the US Food and Drug Administration and the regulatory authorities of some other countries, the sale and use of AA-containing products have been banned or restricted in most countries. However, AA-related adverse events still occur, especially in the Asian and Balkan regions. Therefore, the use of AA-containing herbal remedies and the consumption of food contaminated by AAs still carry high risk. More strict precautions should be taken to protect the public from AA exposure.

Experimental and pan-cancer genome analyses reveal widespread contribution of acrylamide exposure to carcinogenesis in humans

Humans are frequently exposed to acrylamide, a probable human carcinogen found in commonplace sources such as most heated starchy foods or tobacco smoke. Prior evidence has shown that acrylamide causes cancer in rodents, yet epidemiological studies conducted to date are limited and, thus far, have yielded inconclusive data on association of human cancers with acrylamide exposure. In this study, we experimentally identify a novel and unique mutational signature imprinted by acrylamide through the effects of its reactive metabolite glycidamide. We next show that the glycidamide mutational signature is found in a full one-third of approximately 1600 tumor genomes corresponding to 19 human tumor types from 14 organs. The highest enrichment of the glycidamide signature was observed in the cancers of the lung (88% of the interrogated tumors), liver (73%), kidney (>70%), bile duct (57%), cervix (50%), and, to a lesser extent, additional cancer types. Overall, our study reveals an unexpectedly extensive contribution of acrylamide-associated mutagenesis to human cancers.

Aristolochic Acids as Persistent Soil Pollutants: Determination of Risk for Human Exposure and Nephropathy from Plant Uptake

Exposure to aristolochic acids (AAs) from Aristolochia plants is one of the major global causes of nephropathy, including Balkan endemic nephropathy (BEN); renal failure; and urothelial cancer. The high incidence of BEN on the Balkan Peninsula is assumed to result from consumption of Aristolochia clematitis L. seeds coharvested with crops. Here, we show that AAs are long-lived soil contaminants that enter wheat and maize plants by root uptake with strong pH dependence. Soil and crops from Serbian farms in areas endemic for A. clematitis were found to be extensively contaminated with AAs, with contamination strongly correlated with local incidence of BEN. The persistence of AAs as soil contaminants suggests that weed control for A. clematitis plants is needed to reduce the incidence of BEN and aristolochic acid nephropathy, systematic surveys of soil and crop AA levels would identify high-risk regions, and it is imperative to research soil-remediation methods.

Molecular mechanisms of the preventable causes of cancer in the United States

Annually, there are 1.6 million new cases of cancer and nearly 600,000 cancer deaths in the United States alone. The public health burden associated with these numbers has motivated enormous research efforts into understanding the root causes of cancer. These efforts have led to the recognition that between 40% and 45% of cancers are associated with preventable risk factors and, importantly, have identified specific molecular mechanisms by which these exposures modify human physiology to induce or promote cancer. The increasingly refined knowledge of these mechanisms, which we summarize here, emphasizes the need for greater efforts toward primary cancer prevention through mitigation of modifiable risk factors. It also suggests exploitable avenues for improved secondary prevention (which includes the development of therapeutics designed for cancer interception and enhanced techniques for noninvasive screening and early detection) based on detailed knowledge of early neoplastic pathobiology. Such efforts would complement the current emphasis on the development of therapeutic approaches to treat established cancers and are likely to result in far greater gains in reducing morbidity and mortality.