Long non-coding RNA 00607 as a tumor suppressor by modulating NF-κB p65/p53 signaling axis in hepatocellular carcinoma.

Accumulating evidence suggests that long non-coding RNA (lncRNA) plays important roles in some malignant tumors. However, the mechanism underlying how lncRNA regulates hepatocellular carcinoma (HCC) process remains largely unknown. In this study, we explored the potential role of lncRNA 00607 as a novel tumor suppressor in HCC. In this study, we examined the regulation of lncRNA 00607 by the important inflammatory cytokine tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). We also determined the expression of LINC000607 in 159 HCC tumors and paired adjacent tissues. Effects of LINC000607 in HCC proliferation and apoptosis were examined in vitro in HCC cell lines and in vivo tumor xenografts. Furthermore, we also examine underlying mechanism by which lncRNA 00607 regulates NF-κB p65 and how LIN00607 exerts its tumor suppressor role in HCC. We found that lncRNA 00607 expression level is lower in HCC tumors compared with matched normal liver tissue, and its low expression predicts worse prognosis in HCC. Functionally, lncRNA 00607 overexpression leads to decreased HCC cell proliferation in vitro and in vivo, enhanced apoptosis and chemotherapeutic drug sensitivity. Mechanistically, lncRNA 00607 inhibits the p65 transcription by binding to the p65 promoter region, therefore contributing to increased p53 levels in HCC. Taken together, the findings of this study show that the TNF-α/IL-6-lncRNA 00607-NF-κB p65/p53 signaling axis represents a novel therapeutic avenue in cancer chemotherapy.

Diagnosis and therapeutic monitoring of inborn errors of metabolism in 100,077 newborns from Jining city in China.

BACKGROUND: Mandatory newborn screening for metabolic disorders has not been implemented in most parts of China. Newborn mortality and morbidity could be markedly reduced by early diagnosis and treatment of inborn errors of metabolism (IEM). Methods of screening for IEM by tandem mass spectrometry (MS/MS) have been developed, and their advantages include rapid testing, high sensitivity, high specificity, high throughput, and low sample volume (a single dried blood spot). METHODS: Dried blood spots of 100,077 newborns obtained from Jining city in 2014-2015 were screened by MS/MS. The screening results were further confirmed by clinical symptoms and biochemical analysis in combination with the detection of neonatal deficiency in organic acid, amino acid, or fatty acid metabolism and DNA analysis. RESULTS: The percentages of males and females among the 100,077 infants were 54.1% and 45.9%, respectively. Cut-off values were established by utilizing the percentile method. The screening results showed that 98,764 newborns were healthy, and 56 out of the 1313 newborns with suspected IEM were ultimately diagnosed with IEM. Among these 56 newborns, 19 (1:5267) had amino acid metabolism disorders, 26 (1:3849) had organic acid metabolism disorders, and 11 (1:9098) had fatty acid oxidation disorders. In addition, 54 patients with IEM were found to carry mutations, and the other 2 patients had argininemia. CONCLUSIONS: Fifty-six cases of metabolic disorders in Jining were confirmed via newborn screening (NBS) by MS/MS. Early diagnosis and treatment are crucial for the survival and well-being of affected children. A nationwide NBS program using MS/MS is recommended, especially in poor areas of China.

Novel chaetospirolactone and orsellide F from an endophytic fungus Chaetomium sp.

Chaetospirolactone (1), a novel spiro-lactone bearing a rare 1-oxaspiro [4.4] non-7-ene-2,6-dione skeleton, and orsellide F (2), together with six known compounds (3-8), were isolated from an endophytic fungus Chaetomium sp. NF00754. Their structures were determined by interpretation of spectroscopic data. The absolute configurations of 1 and 2 were established by analysis of single X-ray crystallographic data and CD spectra. Compounds 3, 4, and 6 showed moderate acetylcholinesterase inhibitory activity with IC50 values of 7.34, 5.19, and 7.67 µM, respectively.

Rifamorpholines A-E, potential antibiotics from locust-associated actinobacteria Amycolatopsis sp. Hca4.

Cultivation of locust associated rare actinobacteria, Amycolatopsis sp. HCa4, has provided five unusual macrolactams rifamorpholines A-E. Their structures were determined by interpretation of spectroscopic and crystallographic data. Rifamorpholines A-E possess an unprecedented 5/6/6/6 ring chromophore, representing a new subclass of rifamycin antibiotics. The biosynthetic pathway for compounds 1-5 involves a key 1,6-cyclization for the formation of the morpholine ring. Compounds 2 and 4 showed potent activities against methicillin-resistant Staphylococcus aureus (MRSA) with MICs of 4.0 and 8.0 µM, respectively.

CXCL5 contributes to tumor metastasis and recurrence of intrahepatic cholangiocarcinoma by recruiting infiltrative intratumoral neutrophils.

CXCL5 is a member of the CXC-type chemokine family that may play a role in carcinogenesis and cancer progression. This study investigates the biological function and clinical significance of CXCL5 in intrahepatic cholangiocarcinoma (ICC). We demonstrated that CXCL5 was overexpressed in ICC cell lines and tumor samples compared with paired normal tissues. CXCL5 had a direct chemoattractant effect on neutrophils in vitro through PI3K-Akt and extracellular signal-regulated kinase 1/2 signaling pathways. In animal studies, CXCL5 promoted tumor growth and metastasis without altering in vitro proliferative and invasive ability of ICC cells, and this effect was mediated by the recruitment of intratumoral infiltrative neutrophils by tumor-derived CXCL5. Immunohistochemical analysis of ICC samples showed that overexpression of CXCL5 correlated strongly with intratumoral neutrophil infiltration, shorter overall survival and high tumor recurrence. Multivariate analysis revealed that CXCL5 overexpression alone, or combined with the presence of intratumoral neutrophils, was an independent prognostic indicator for ICC. In conclusion, our data showed that CXCL5 promotes ICC growth and metastasis by recruiting intratumoral neutrophils. CXCL5 alone or combined with intratumoral neutrophils is a novel prognostic predictor for ICC patients and a potential therapeutic target.

αB-crystallin complexes with 14-3-3ζ to induce epithelial-mesenchymal transition and resistance to sorafenib in hepatocellular carcinoma.

UNLABELLED: The overall survival of patients with hepatocellular carcinoma (HCC) remains poor, and the molecular pathogenesis remains incompletely defined in HCC. Here we report that increased expression of αB-Crystallin in human HCC predicts poor survival and disease recurrence after surgery. Multivariate analysis identifies αB-Crystallin expression as an independent predictor for postoperative recurrence and overall survival. We show that elevated expression of αB-Crystallin promotes HCC progression in vivo and in vitro. We demonstrate that αB-Crystallin overexpression fosters HCC progression by inducing epithelial-mesenchymal transition (EMT) in HCC cells through activation of the extracellular-regulated protein kinase (ERK) cascade, which can counteract the effect of sorafenib. αB-Crystallin complexes with and elevates 14-3-3ζ protein, leading to up-regulation of ERK1/2 activity. Moreover, overexpression of αB-Crystallin in HCC cells induces EMT progression through an ERK1/2/Fra-1/slug signaling pathway. Clinically, our data reveal that overexpression of both αB-Crystallin and 14-3-3ζ correlates with the HCC poorest survival outcomes, and sorafenib response is impaired in patients with αB-Crystallin overexpression. CONCLUSION: These data suggest that the αB-Crystallin-14-3-3ζ complex acts synergistically to promote HCC progression by constitutively activating ERK signaling. This study reveals αB-Crystallin as a potential therapeutic target for HCC and a biomarker for predicting sorafenib treatment response. (HEPATOLOGY 2013).

B7-H3 is expressed in human hepatocellular carcinoma and is associated with tumor aggressiveness and postoperative recurrence.

B7-H3, a novel B7 family member, positively or negatively regulates T-cell responses. We investigated the clinical relevance and prognostic significance of B7-H3 in hepatocellular carcinoma (HCC). Western blotting showed B7-H3 upregulation in 17 of 24 (70.8 %) HCC tissues compared with nontumor liver tissues (p = 0.028). B7-H3 immunostaining on tissue microarrays containing 240 HCC patient samples indicated that 225 (93.8 %) tumors had aberrant B7-H3 expression, with strong intensity in 79 (32.9 %) cases, whereas B7-H3 expression in peritumor liver cells was weak in most cases (226; 94.2 %). Notably, patients with high/moderate tumor cell B7-H3 expression showed significantly poorer survival (p = 0.009) and increased recurrence (p = 0.002). After multivariable adjustment, high/moderate B7-H3 expression remained significant for an increased risk of recurrence (hazard ratio = 1.79; 95 % confidence interval = 1.19-2.70; p = 0.005). B7-H3 expression correlated with invasive phenotypes like vascular invasion and advanced tumor stage, and the metastatic potential of HCC cell lines. Flow cytometry showed that B7-H3 expression is inversely correlated with proliferation and interferon-γ production by infiltrating T cells. Interferon-γ stimulation significantly upregulated B7-H3 expression in HCC cells in vitro, implicating B7-H3 expression as a feedback mechanism to evade anti-tumor immunity. Importantly, the prognostic value of B7-H3 expression was validated in an independent cohort of 206 HCC patients. Collectively, our data suggest that B7-H3 was abundantly expressed in HCC and was associated with adverse clinicopathologic features and poor outcome. Thus, B7-H3 represents an attractive target for diagnostic and therapeutic manipulation in human HCC.

Infiltrating memory/senescent T cell ratio predicts extrahepatic metastasis of hepatocellular carcinoma.

BACKGROUND: The density of tumor-infiltrating immunocytes (TICs) has been proposed as an independent predictor of intrahepatic recurrence in patients with hepatocellular carcinoma (HCC). However, the relative roles of TIC density in predicting tumor extrahepatic metastasis remain to be elucidated. METHODS: The densities of CD3(+), CD8(+), granzyme B(+), FoxP3(+), CD45RO(+), CD20(+), CD1a(+), CD83(+), CD57(+), and CD68(+) TICs were assessed by immunohistochemistry in tissue microarrays containing paired intratumoral (IT) and peritumoral (PT) tissues from 206 consecutive HCC patients who underwent liver transplantation. Occurrence of extrahepatic metastasis, recurrence-free survival (RFS), and cancer-specific survival (CSS) were assessed retrospectively in relation to TIC densities. RESULTS: CD45RO(+) memory T cell density was lower in tumor tissue compared with peritumor, whereas CD57(+) senescent T cell density was higher. Univariate analysis revealed that increased CD45RO (IT) (+) and decreased CD57 (PT) (+) densities were statistically significantly associated with favorable RFS and CSS, while other types of TICs, intratumorally or peritumorally, showed no prognostic values. Further, the CD45RO (IT) (+) /CD57 (PT) (+) ratio could stratify patients more accurately in terms of RFS and CSS than either marker used alone. Finally, multivariate analysis indicated that a high CD45RO (IT) (+) /CD57 (PT) (+) ratio was independently associated with better RFS (hazard ratio [HR] = 0.64; 95% confidence interval [CI], 0.42 to 0.98; P = 0.040) and CSS (HR = 0.51; 95% CI, 0.31 to 0.83; P = 0.007), but not CD45RO (IT) (+) or CD57 (PT) (+) individually. CONCLUSIONS: These results suggest that the CD45RO (IT) (+) /CD57 (PT) (+) (memory/senescent T cell) ratio is of vital importance in preventing HCC extrahepatic metastasis and in particular demonstrates its independent prognostic value in liver transplant recipients.

Intratumoral neutrophils: a poor prognostic factor for hepatocellular carcinoma following resection.

BACKGROUND & AIMS: Neutrophil infiltration has been linked to clinical outcome of various cancer types. However, its role in hepatocellular carcinoma (HCC) is unclear. In this study, we investigated prognostic values for intratumoral and peritumoral neutrophils in HCC patients undergoing curative resection. METHODS: The expression of CD66b, CD8, TGF-beta, and CD34 was assessed by immunohistochemistry in tissue microarrays containing paired intratumoral and peritumoral tissues from 197 patients receiving curative resection for HCC. Prognostic values for these and other clinicopathologic factors were evaluated. RESULTS: Intratumoral CD66b(+) neutrophils significantly correlated with CD8(+) T cells (r=0.240, p=0.004), TGF-beta expression (p=0.012), BCLC stage (p=0.016), and early recurrence (p=0.041). Increased intratumoral neutrophils were significantly associated with decreased RFS/OS (p=0.001 and p<0.001, respectively) in univariate analysis and were identified as an independent prognostic factor (HR=1.845, 95% CI=1.169-2.911, p=0.008 for RFS; HR=2.578, 95% CI=1.618-4.106, p<0.001 for OS) in multivariate analysis. Intratumoral neutrophil-to-CD8(+) T cell ratio (iNTR) better predicted the outcome in terms of minimum p values. Intratumoral neutrophils were also demonstrated to be statistically predictive for RFS/OS in the normal AFP subgroup, small HCC subgroup, and validation cohort. However, peritumoral neutrophils were not associated with the outcome of HCC. CONCLUSIONS: The presence of intratumoral neutrophils was a poor prognostic factor for HCC after resection. Intratumoral neutrophil-to-CD8(+) T cell ratio was a better predictor of outcome.

Overexpression of PD-L1 significantly associates with tumor aggressiveness and postoperative recurrence in human hepatocellular carcinoma.

PURPOSE: The aberrant expression of programmed cell death 1 ligands 1 and 2 (PD-Ls) on tumor cells dampens antitumor immunity, resulting in tumor immune evasion. In this study, we investigated the expression of PD-Ls in human hepatocellular carcinoma (HCC) to define their prognostic significance after curative surgery. EXPERIMENTAL DESIGN: Immunohistochemistry was used to investigate PD-Ls expression as well as granzyme B+ cytotoxic and FoxP3+ regulatory T cell infiltration on tissue microarrays containing 240 randomly selected HCC patients who underwent surgery. The results were further verified in an independent cohort of 125 HCC patients. PD-Ls expression on HCC cell lines was detected by Western blot assay. RESULTS: Patients with higher expression of PD-L1 had a significantly poorer prognosis than patients with lower expression. Although patients with higher expression of PD-L2 also had a poorer survival, the difference in recurrence was not statistically significant. Multivariate analysis identified tumor expression of PD-L1 as an independent predictor for postoperative recurrence. No correlation was found between PD-Ls expression and granzyme B+ lymphocyte infiltration, whereas a significant positive correlation was detected between PD-Ls expression and FoxP3+ lymphocyte infiltration. In addition, tumor-infiltrating cytotoxic and regulatory T cells were also independent prognosticators for both survival and recurrence. The prognostic value of PD-L1 expression was validated in the independent data set. CONCLUSION: Our data suggest for the first time that PD-L1 status may be a new predictor of recurrence for HCC patients and provide the rationale for developing a novel therapy of targeting the PD-L1/PD-1 pathway against this fatal malignancy.

Dalestones A and B, two anti-inflammatory cyclopentenones from Daldinia eschscholzii with an edited strong promoter for the global regulator LaeA-like gene.

Replacement of the native promoter of theglobal regulator LaeA-like gene of Daldinia eschscholzii by a strong gpdA promoter led to the generation of two novel cyclopentenone metabolites, named dalestones A and B, whose structures were assigned by a combination of spectroscopic analysis, modified Mosher's reaction, and electronic circular dichroism (ECD). Dalestones A and B inhibit the gene expression of TNF-α and IL-6 in LPS-induced RAW264.7 macrophages.

Selection of reference genes for real-time PCR in human hepatocellular carcinoma tissues.

AIMS: To investigate the most suitable housekeeping genes for quantifying a change in mRNA expression levels due to hepatitis virus B related hepatocellular carcinoma (HCC). METHODS: Expression of mRNA encoding ACTB, GAPDH, B2M, HPRT and TBP was measured using quantitative reverse transcription polymerase chain reaction (qRT-PCR) in matched malignant and non-malignant tissues obtained from 65 non-treated HCCs. The software programs geNorm and NormFinder were used to ascertain the most suitable reference gene combination. RESULTS: All candidate genes showed significantly different expression between malignant and non-malignant samples. GAPDH and ACTB, genes most frequently used for normalization, were heavily regulated during HCC carcinogenesis and progression. B2M expression levels varied with hepatitis infection status. The combination of HPRT and TBP expression levels were the most stable, regardless of differences in tumor stage and cirrhotic and malignancy status. CONCLUSIONS: It is necessary to select reference genes based on tissue and disease specific expression profile and to further identify novel reference genes with greater expression stability for use in HBV related HCC gene expression studies.

[Interferon-alpha upregulates thymidine phosphorylase expression via JAK-STAT transcriptional activation and mRNA stabilization in human hepatocellular carcinoma SMMC-7721 cells].

OBJECTIVE: To examine how the thymidine phosphorylase (TP) gene expression is upregulated by interferon-alpha (IFN-alpha) in human hepatocellular carcinoma SMMC-7721 cells. METHODS: TP mRNA levels were determined by RT-PCR. Whether the JAK-STAT cascade mediates IFN-alpha-induced TP mRNA expression was studied by pretreatment with Janus Kinase (JAK) inhibitor, AG-490. Effects of IFN-alpha on TP mRNA stability were detected with additional actinomycin D. RESULTS: The expression of TP mRNA was induced by IFN-alpha in a dose- and time-dependent manner in SMMC-7721 (human hepatocellular carcinoma) cells. TP mRNA levels rose at 8 h, reached the peak value at 12 h, and remained at a high level up to 72 h in SMMC-7721 cells treated with IFN-alpha 10000 U/ml. IFN-alpha at a dose of 5000 or 10000 U/ml up-regulated TP expression about 3 fold compared with that of non-treated cells (P < 0.05). Induction of TP mRNA expression by IFN-alpha was significantly inhibited in SMMC-7721 cells by pretreatment with AG-490, in comparison with that treated with IFN-alpha alone. Pretreatment of SMMC-7721 cells with IFN-alpha 10000 U/ml for 24 h caused a substantial stabilization of TP mRNA, with a half-live of 35.8 h, compared with 8.5 hr in the control SMMC-7721 cells. CONCLUSION: IFN-alpha at certain doses upregulates TP mRNA expression via both JAK-STAT transcriptional activation and post-transcriptional mRNA stabilization in human hepatocellular carcinoma SMMC-7721 cells.

Guidelines for Diagnosis and Treatment of Primary Liver Cancer in China (2017 Edition).

BACKGROUND: Hepatocellular carcinoma (HCC) (about 85-90% of primary liver cancer) is particularly prevalent in China because of the high prevalence of chronic hepatitis B infection. HCC is the fourth most common malignancy and the third leading cause of tumor-related deaths in China. It poses a significant threat to the life and health of Chinese people. SUMMARY: This guideline presents official recommendations of the National Health and Family Planning Commission of the People's Republic of China on the surveillance, diagnosis, staging, and treatment of HCC occurring in China. The guideline was written by more than 50 experts in the field of HCC in China (including liver surgeons, medical oncologists, hepatologists, interventional radiologists, and diagnostic radiologists) on the basis of recent evidence and expert opinions, balance of benefits and harms, cost-benefit strategies, and other clinical considerations. KEY MESSAGES: The guideline presents the Chinese staging system, and recommendations regarding patients with HCC in China to ensure optimum patient outcomes.

[Interferon alpha enhances the sensitivity of SMMC-7721 hepatocellular carcinoma cells to 5'-deoxy-5-fluorouridine related to up-regulation of thymidine phosphorylase].

OBJECTIVE: To observe changes of sensitivity to 5'-deoxy-5-fluorouridine (5'-dFUrd), and 5-fluorouracil (5-FU) in SMMC-7721 hepatocellular carcinoma cells by interferon alpha (IFN-alpha), and its relationship with the expression of thymidine phosphorylase (TP). METHODS: TP mRNA expression was determined by RT-PCR. Cytotoxicity of 5'-dFUrd, and 5-FU against SMMC-7721 cells was evaluated by MTT assay. RESULTS: Expression levels of TP mRNA was elevated in SMMC-7721 cells after cultured with IFN-alpha, which was a concentration- and time-dependent increase. After SMMC-7721 cells was treated in the concentration of 5000 U/ml, and 10 000 U/ml IFN-alpha, the level of TP mRNA was significantly higher than that in untreated control (P < 0.05). When SMMC-7721 cells was cultured with the concentration 10 000 U/ml IFN-alpha, the level of TP mRNA rose at 8hr, reached the peak value at 12hr, and remained high level up to 72hr. IFN-alpha enhanced the sensitivity of SMMC-7721 cells to 5'-dFUrd with dose-dependent increase. IFN-alpha (10 000 U/ml) reduced IC(50) of 5'-dFUrd from (102.1 +/- 18.4) micromol/L to (34.2 +/- 4.1) micromol/L (P < 0.05). There was no obvious relation between use of IFN-alpha and 5-FU sensitivity. IC(50) of 5-FU was (5.8 +/- 2.0) micromol/L and (6.3 +/- 1.4) micromol/L in with IFN-alpha (10 000 U/ml) and control group, respectively. Under the use of interferon, sensitivity to 5'-dFUrd increased positively related to up-regulation of TP mRNA expression. CONCLUSION: IFN-alpha enhanced cytotoxicity of 5'-dFUrd against SMMC-7721 cells positively related to its induction of TP mRNA.

Amycolamycins A and B, Two Enediyne-Derived Compounds from a Locust-Associated Actinomycete.

Two novel enediyne-derived natural products, amycolamycins A and B (1 and 2), were characterized from a locust-associated actinomycete Amycolatopsis sp. HCa4. Amycolamycins A and B contain a unique 2-(cyclopenta[a]inden-5-yl)oxirane core with suspected enediyne polyketide biosynthetic origin. Sequencing and analysis of the acm biosynthetic gene cluster allowed us to propose the biosynthetic pathway of 1 and 2. Moreover, amycolamycin A (1) was selectively cytotoxic to the M231 breast cancer cell line.

Conversion to sirolimus immunosuppression in liver transplantation recipients with hepatocellular carcinoma: Report of an initial experience.

AIM: To report a retrospective analysis of preliminary results of 36 patients who received sirolimus (SRL, Rapamune, rapamycin) in a consecutive cohort of 248 liver allograft recipients. METHODS: Thirty-six liver transplant patients with hepatocellular carcinoma (HCC) who were switched to SRL-based immunosuppression therapy from tacrolimus were enrolled in this study. The patients who were diagnosed as advanced HCC before orthotopic liver transplantation (OLT) were divided into group A (n = 11), those who were found to have HCC recurrence and/or metastasis after OLT were assigned to group B (n = 18), and those who developed renal insufficiency caused by calcineurin inhibitor (CNI) were assigned to group C (n = 7) after OLT. RESULTS: The patients were followed up for a median of 10.4 mo (range, 3.8-19.1 mo) after conversion to SRL therapy and 12.3 mo (range, 5.1-34.4 mo) after OLT. Three patients developed mild acute cellular rejection 2 wk after initiating SRL therapy, which was fully reversed after prednisolone pulse therapy. In group A, only 1 patient was found to have HCC recurrence and metastasis 12 mo after OLT. In group B, 66.7% (12/18) patients (2 with progressive tumor, 7 with stable tumor and 3 without tumor) were still alive due to conversing to SRL and/or resection for HCC recurrence at the end of a median follow-up of 6.8 mo post conversion and 10.7 mo posttransplant. In group C, no HCC recurrence was demonstrated in 7 patients, and renal function became normal after SRL therapy. Thrombocytopenia (n = 2), anemia (n = 8), and oral aphthous ulcers (n = 7) found in our cohort were easily manageable. CONCLUSION: The conversion to SRL-based immunosuppression may inhibit the recurrence and metastasis of HCC and improve CNI-induced renal insufficiency in OLT patients with HCC.

[Analysis of the risk factors influencing the prognosis of orthotopic liver transplantation for hepatocellular carcinoma and summary of relevant clinical experience].

OBJECTIVE: To analyze the risk factors influencing the prognosis of orthotopic liver transplantation for hepatocellular carcinoma (HCC) and sum up the relevant clinical experience in diagnosis and treatment of HCC. METHODS: The clinical data of 198 HCC patients, 177 males and 21 females, aged 49 (24-83), were analyzed. RESULTS: The 0.5-, 1-, and 2-year survival rates were 89%, 78%, and 65 respectively. The rates of disease-free survival (DFS) were 85%, 73, and 67% respectively. Univariate analysis revealed that tumor size, presence of vascular invasion, Edmondson grade, TNM classification, and preoperative alpha-fetoprotein (AFP) were significantly related to DFS, and the 4 foregoing factors were also related to the survival rate. Cox regression analysis suggested that presence of vascular invasion was an independent prognostic factor of survival rate and DFS. CONCLUSION: Vascular invasion plays a leading role in evaluating the prognosis of orthotopic liver transplantation for HCC. It is important to discover the micro-metastasis and explore more effective approaches to prevent recurrence after transplantation.

Dimerization of human uridine diphosphate glucuronosyltransferase allozymes 1A1 and 1A9 alters their quercetin glucuronidation activities.

Uridine diphosphate glucuronosyltransferase 1A (UGT1A) is a major phase II drug-metabolism enzyme superfamily involved in the glucuronidation of endobiotics and xenobiotics in humans. Many polymorphisms in UGT1A genes are reported to inhibit or decrease UGT1A activity. In this study, two UGT1A1 allozymes, UGT1A1 wild-type and a splice mutant, as well as UGT1A9 wild-type and its three UGT1A9 allozymes, UGT1A9*2(C3Y), UGT1A9*3(M33T), and UGT1A9*5(D256N) were single- or double-expressed in a Bac-to-Bac expression system. Dimerization of UGT1A1 or UGT1A9 allozymes was observed via fluorescence resonance energy transfer (FRET) and co-immunoprecipitation analysis. SNPs of UGT1A altered the ability of protein-protein interaction, resulting in differential FRET efficiencies and donor-acceptor r distances. Dimerization changed the chemical regioselectivity, substrate-binding affinity, and enzymatic activity of UGT1A1 and UGT1A9 in glucuronidation of quercetin. These findings provide molecular insights into the consequences of homozygous and heterozygous UGT1A1 and UGT1A9 allozymes expression on quercetin glucuronidation.