A tumor endothelial cell-specific microRNA replacement therapy for hepatocellular carcinoma.

Current approved anti-angiogenic drugs (AAD) for hepatocellular carcinoma (HCC) inhibit tumor angiogenesis, but affect the hepatic vasculature resulting in adverse effects. Tumor endothelial cells (TECs) differ from normal endothelial cells. In this study, we aimed to detect TEC-specific miRNAs and develop an anti-angiogenic treatment specific for TECs. We established HCC orthotopic mouse models. TEC-specific miRNAs were detected using a microRNA array. Finally, we evaluated the therapeutic effects of the TEC-specific miRNA agonist cocktail. In total, 260 TEC-specific genes were detected. Among the top ten downregulated TEC-specific miRNAs, miR-139-3p and 214-3p were important for the TEC phenotype. The TEC-specific microRNA agonist cocktail showed significant anti-tumor effects by inhibiting tumor angiogenesis without affecting hepatic vasculatures in HCC orthotopic mouse models. Moreover, it significantly downregulated tip-cell sprouting-related genes. We identified two downregulated TEC-specific miRNAs; microRNA replacement therapy, which targets the downregulated TEC-specific miRNAs, is an effective and promising treatment for HCC.

Tumor-derived insulin-like growth factor-binding protein-1 contributes to resistance of hepatocellular carcinoma to tyrosine kinase inhibitors.

BACKGROUND: Antiangiogenic tyrosine kinase inhibitors (TKIs) provide one of the few therapeutic options for effective treatment of hepatocellular carcinoma (HCC). However, patients with HCC often develop resistance toward antiangiogenic TKIs, and the underlying mechanisms are not understood. The aim of this study was to determine the mechanisms underlying antiangiogenic TKI resistance in HCC. METHODS: We used an unbiased proteomic approach to define proteins that were responsible for the resistance to antiangiogenic TKIs in HCC patients. We evaluated the prognosis, therapeutic response, and serum insulin-like growth factor-binding protein-1 (IGFBP-1) levels of 31 lenvatinib-treated HCC patients. Based on the array of results, a retrospective clinical study and preclinical experiments using mouse and human hepatoma cells were conducted. Additionally, in vivo genetic and pharmacological gain- and loss-of-function experiments were performed. RESULTS: In the patient cohort, IGFBP-1 was identified as the signaling molecule with the highest expression that was inversely associated with overall survival. Mechanistically, antiangiogenic TKI treatment markedly elevated tumor IGFBP-1 levels via the hypoxia-hypoxia inducible factor signaling. IGFBP-1 stimulated angiogenesis through activation of the integrin α5ß1-focal adhesion kinase pathway. Consequently, loss of IGFBP-1 and integrin α5ß1 by genetic and pharmacological approaches re-sensitized HCC to lenvatinib treatment. CONCLUSIONS: Together, our data shed light on mechanisms underlying acquired resistance of HCC to antiangiogenic TKIs. Antiangiogenic TKIs induced an increase of tumor IGFBP-1, which promoted angiogenesis through activating the IGFBP-1-integrin α5ß1 pathway. These data bolster the application of a new therapeutic concept by combining antiangiogenic TKIs with IGFBP-1 inhibitors.

The Clinical Impact of Hepatic Arterial Infusion Chemotherapy New-FP for Hepatocellular Carcinoma with Preserved Liver Function.

Background: Systemic treatments are recommended for advanced hepatocellular carcinoma (HCC) in preserved liver function. However, their effects are unsatisfactory in some tumor conditions, particularly macrovascular invasion (MVI) including major portal vein tumor thrombus (PVTT). We compared the efficacy of hepatic arterial infusion chemotherapy (HAIC) regimens New-FP and sorafenib for various tumor conditions in preserved liver function. Methods: We retrospectively collected the data of 1709 patients with HCC who were treated with New-FP or sorafenib. Survival was assessed after propensity score matching. Subgroup analyses were conducted: cohort 1 (no MVI or extrahepatic spread (EHS)), cohort 2 (MVI only), cohort 3 (EHS only), cohort 4 (MVI and EHS), and cohort 5 (major PVTT). Results: The New-FP group had a longer median survival time (MST) than the sorafenib in the whole analysis (18 vs. 9 months; p < 0.0001). New-FP demonstrated a longer MST compared with sorafenib in cohort 2 and cohort 4. In cohort 5, the MST of the New-FP group was 16 months, while that of sorafenib was 6 months (p < 0.0001). For major PVTT-HCC, the response rate of New-FP was 73.0%. The MST of patients who achieved complete response with New-FP was 59 months. Conclusions: HAIC using New-FP is promising for patients with MVI- and major PVTT-HCC in preserved liver function.

Subcutaneous Fat Thickness of the Lower Limb is Associated with Trunk Muscle Mass in Patients with Hepatocellular Carcinoma: A Simple Assessment for Sarcopenia Using Conventional Ultrasonography.

OBJECTIVE: Trunk muscle mass can be evaluated by skeletal muscle index (SMI), which is a prognostic factor in patients with hepatocellular carcinoma (HCC); however, this requires the use of computed tomography, and a simpler assessment for trunk muscle mass is urgently needed. We aimed to examine whether an association between SMI and lower extremity compartments including muscle and subcutaneous fat thickness of lower limbs (SFT-LL) could be identified by means of ultrasonography in patients with HCC. METHODS: We retrospectively enrolled male patients with HCC (n=30). Trunk muscle mass was evaluated by SMI using computed tomography. Ultrasonography was used for assessment of muscle and SFT-LL. Factors associated with SMI were evaluated by decision-tree analysis. RESULTS: There was no significant correlation between SMI and muscle thickness of lower limbs. However, a significant correlation was seen between SMI and left SFT-LL (r=0.406, P=0.026). In decision-tree analysis for SMI, left SFT-LL was selected as the initial split variable with an optimal cut-off value of 5 mm. In patients with left SFT-LL ≥ 5 mm, SMI was 39.4±3.4 cm2/m2, whereas SMI was 31.6±6.3 cm2/m2 in patients with left SFT-LL <5 mm. CONCLUSION: Left SFT-LL evaluated by ultrasonography was associated with SMI. Thus, ultrasonography may be a useful tool to evaluate trunk muscle mass. Moreover, left SFT-LL may be a useful indicator of sarcopenia in patients with HCC.

Clinical Importance of Regimens in Hepatic Arterial Infusion Chemotherapy for Advanced Hepatocellular Carcinoma with Macrovascular Invasion.

Macroscopic vascular invasion (MVI) is a poor prognostic factor in hepatocellular carcinoma (HCC). Hepatic arterial infusion chemotherapy (HAIC) is a promising treatment in MVI-HCC. However, it is not clear which regimens are suitable for HAIC. In this study, we aimed to compare the therapeutic effects between New FP (a fine-powder cisplatin suspended with lipiodol plus 5-fluorouracil) and low dose FP (LFP/cisplatin plus 5-fluorouracil) in the treatment of MVI-HCC patients with Child-Pugh class A. New FP is a regimen that consists of a fine-powder cisplatin suspended with lipiodol and 5-fluorouracil. Fifty-one patients were treated with LFP, and 99 patients were New FP. We compared the therapeutic effects of LFP and New FP and assessed factors that associated with the therapeutic effects. The median survival and progression-free survival times of LFP and New FP were 16.1/24.7 and 5.4/8.8 months, respectively (p < 0.05, p < 0.05). The complete response (29%) and objective response rate (76%) of New FP were significantly higher than those of LFP (p < 0.001, p < 0.01). Factors associated with better therapeutic response were better ALBI-grade and New FP treatment choice. New FP is a more powerful regimen than LFP in HAIC for MVI-HCC. New FP represents a recommended HAIC regimen for the treatment of patients with MVI-HCC.

Initial Experience of Atezolizumab Plus Bevacizumab for Unresectable Hepatocellular Carcinoma in Real-World Clinical Practice.

BACKGROUND: Atezolizumab plus bevacizumab was approved for patients with hepatocellular carcinoma (HCC). Although clinical trials have revealed its efficacy, the outcomes in the real-world clinical practice are unclear. We retrospectively evaluated the efficacy and safety of atezolizumab plus bevacizumab for HCC. MATERIALS AND METHODS: This is a multicenter study conducted between November 2020 and March 2021. Among the 61 patients, 51 were assessed for progression-free survival (PFS), therapeutic response, and adverse events (AEs). RESULTS: The median PFS was 5.4 months. The objective response rate (ORR) was 35.3%. The disease control rate (DCR) was 86.3%. The incidence rates of AEs at any grade and grade >3 were 98.0% and 29.4%, respectively. The most frequent AE at any grade and grade >3 was hepatic disorder. In patients with a previous history of molecular targeted agent (MTA) or the degree of albumin-bilirubin (ALBI) grade, there were no significant differences in the PFS, ORR, DCR, and incidence rates of AEs. CONCLUSION: The study demonstrated that atezolizumab plus bevacizumab was effective and safe for patients with HCC even in the real-world setting including patients with a previous MTA history or other than ALBI grade 1.

Survival Benefit of Hepatic Arterial Infusion Chemotherapy over Sorafenib in the Treatment of Locally Progressed Hepatocellular Carcinoma.

BACKROUND: Not all patients with hepatocellular carcinoma (HCC) benefit from treatment with molecular targeted agents such as sorafenib. We investigated whether New-FP (fine-powder cisplatin and 5-fluorouracil), a hepatic arterial infusion chemotherapy regimen, is more favorable than sorafenib as an initial treatment for locally progressed HCC. METHODS: To avoid selection bias, we corrected the data from different facilities that did or did not perform New-FP therapy. In total, 1709 consecutive patients with HCC initially treated with New-FP or sorafenib; 1624 (New-FP, n = 644; sorafenib n = 980) were assessed. After propensity score matching (PSM), overall survival (OS) and prognostic factors were assessed (n = 344 each). Additionally, the patients were categorized into four groups: cohort-1 [(without macrovascular invasion (MVI) and extrahepatic spread (EHS)], cohort-2 (with MVI), cohort-3 (with EHS), and cohort-4 (with MVI and EHS) to clarify the efficacy of each treatment. RESULTS: New-FP prolonged OS than sorafenib after PSM (New-FP, 12 months; sorafenib, 7.9 months; p < 0.001). Sorafenib treatment, and severe MVI and EHS were poor prognostic factors. In the subgroup analyses, the OS was significantly longer the New-FP group in cohort-2. CONCLUSIONS: Local treatment using New-FP is a potentially superior initial treatment compared with sorafenib as a multidisciplinary treatment in locally progressed HCC without EHS.

Increased Arterio-Portal Shunt Formation after Drug-Eluting Beads TACE for Hepatocellular Carcinoma.

BACKGROUND AND AIMS: Conventional transcatheter arterial chemoembolization (C-TACE) and drug-eluting bead (DEB)-based TACE are current treatments for hepatocellular carcinoma (HCC). We compared the therapeutic efficacies and adverse events of these methods in a single-center retrospective cohort study. METHODS: We enrolled 174 patients treated between January 2010 and October 2016; 98 and 76 underwent C-TACE and DEB-TACE, respectively, with 76 and 22 of the former group and 49 and 27 of the latter group classified as Child-Pugh class A and B, respectively. Therapeutic outcomes, progression-free survival (PFS), and adverse events were evaluated. RESULTS: The PFS rates in the C-TACE and DEB-TACE groups were 8.1 and 6.1 months, respectively (p = 0.79). The response and disease control rates were 64 and 71% in C-TACE patients and 69 and 78% in DEB-TACE patients, respectively (p = 0.25). Postprocedural pain, vomiting, and fever were more frequent following C-TACE than DEB-TACE (p < 0.001). In contrast, the incidences of bilomas and arterio-portal shunts were significantly higher following DEB-TACE (p < 0.001); the incident rates of arterio-portal shunt formation were 8.1 and 48.7% in patients undergoing C-TACE and DEB-TACE, respectively. Child-Pugh class A was significantly associated with arterio-portal shunt formation after DEB-TACE on multivariate analysis. CONCLUSIONS: There were no significant differences in the therapeutic efficacies of C-TACE and DEB-TACE. However, the frequency of arterio-portal shunt formation was significantly higher in HCC patients with Child-Pugh class A undergoing DEB-TACE. Our findings imply that C-TACE should be selected for HCC patients with Child-Pugh class A and DEB-TACE should be chosen for those with Child-Pugh class B.

Weekends-Off Lenvatinib for Unresectable Hepatocellular Carcinoma Improves Therapeutic Response and Tolerability toward Adverse Events.

Background: Although lenvatinib has become the standard therapy for hepatocellular carcinoma (HCC), the high incidence rate of adverse events (AEs) is an issue. This study aimed to clarify the AEs of lenvatinib and the therapeutic impact of five days-on/two days-off administration (i.e., weekends-off strategy) for lenvatinib. Methods: We retrospectively assessed the therapeutic effects and AEs of 135 patients treated with lenvatinib, and the improvement of tolerability and therapeutic efficacy of 30 patients treated with the weekends-off strategy. We also evaluated lenvatinib-induced vascular changes in tumors and healthy organs using a mouse hepatoma model. Results: The incidence rates of any grade and grade ≥ 3 AEs were 82.1% and 49.6%. Fatigue was the most important AE since it resulted in dose reduction and discontinuation. Of the 30 patients who received weekends-off lenvatinib, 66.7% tolerated the AEs. Although 80.8% of the patients showed progression after dose reduction, the therapeutic response improved in 61.5% of the patients by weekends-off lenvatinib. Notably, weekends-off administration significantly prolonged the administration period and survival (p < 0.001 and p < 0.05). The mouse hepatoma model showed that weekends-off administration contributed to recovery of vascularity in the organs. Conclusion: Weekends-off administration of lenvatinib was useful to recover the therapeutic response and tolerability toward AEs.

Dose and Location of Irradiation Determine Survival for Patients with Hepatocellular Carcinoma with Macrovascular Invasion in External Beam Radiation Therapy.

AIM: Prognosis of hepatocellular carcinoma (HCC) with macrovascular invasion (MVI) is extremely poor. However, proper therapeutic strategies have not been established yet. The purpose of this study is to identify the effects of external beam radiation therapy (EBRT) for MVI of HCC. METHODS: We have analyzed and evaluated 80 consecutive patients with HCC with MVI who underwent EBRT, and factors associated with enhanced survival in EBRT were evaluated by univariate and multivariate analysis. RESULTS: The local response rate of radiotherapy for the irradiated MVI was 66.2%. The time to progression of the irradiated MVI was 5.8 months. Univariate and multivariate analyses showed that the higher irradiation dose (over 45 Gy) and the irradiation location (hepatic vein tumor thrombus - HVTT) were significant factors associated with survival benefits of EBRT. The response of EBRT for HVTT was significantly superior to that for portal vein or bile duct tumor thrombus. CONCLUSION: We conclude that a multidisciplinary therapeutic strategy based on EBRT should be proactively selected in the treatment of advanced HCC with MVI.

Epirubicin is More Effective than Miriplatin in Balloon-Occluded Transcatheter Arterial Chemoembolization for Hepatocellular Carcinoma.

BACKGROUND: Transcatheter arterial chemoembolization (TACE) is a standard therapy used in the treatment of intermediate hepatocellular carcinoma (HCC). Recently, balloon-occluded TACE (B-TACE) has been developed. PURPOSE: This study aimed to clarify the effects of B-TACE in patients with HCC, with a focus on which drug is suitable to suspend in Lipiodol for B-TACE. METHODS: We retrospectively evaluated 35 patients with HCC treated with B-TACE. Factors associated with enhanced time to progression (TTP) after B-TACE were evaluated using univariate and multivariate analyses. RESULTS: A total of 35 patients with HCC (40 nodules) were treated with B-TACE between June 2013 and August 2016. Epirubicin was used in 25 nodules and miriplatin was used in 15 nodules. Epirubicin (15.1 months) was significantly better than miriplatin (3.2 months) in prolonging the local TTP after B-TACE (p = 0.0293). Epirubicin showed a positive tendency in TE4 (100% tumor necrosis) rate when compared with miriplatin (p = 0.058). Achievement of TE4 was the only significant factor associated with better TTP after B-TACE. Epirubicin- and TACE-naïve statuses were significant factors in achieving TE4 with B-TACE. CONCLUSION: To enhance the TTP with B-TACE, TE4 should be achieved. Epirubicin is a more optimal anticancer drug (as a Lipiodol suspension) than miriplatin for achieving TE4 with B-TACE.

Seasonal induction of alternative principal pathway for rose flower scent.

Ecological adaptations to seasonal changes are often observed in the phenotypic traits of plants and animals, and these adaptations are usually expressed through the production of different biochemical end products. In this study, ecological adaptations are observed in a biochemical pathway without alteration of the end products. We present an alternative principal pathway to the characteristic floral scent compound 2-phenylethanol (2PE) in roses. The new pathway is seasonally induced in summer as a heat adaptation that uses rose phenylpyruvate decarboxylase (RyPPDC) as a novel enzyme. RyPPDC transcript levels and the resulting production of 2PE are increased time-dependently under high temperatures. The novel summer pathway produces levels of 2PE that are several orders of magnitude higher than those produced by the previously known pathway. Our results indicate that the alternative principal pathway identified here is a seasonal adaptation for managing the weakened volatility of summer roses.

Influence of exogenously applied abscisic acid on carotenoid content and water uptake in flowers of the tea plant (Camellia sinensis).

BACKGROUND: Carotenoids are a major class of plant pigments and fulfill many functions in different organisms that either produce or consume them. Although the color of the stamina of tea (Camellia sinensis) flowers is clearly due to the presence of carotenoids, the carotenoid profile and content remain to be discovered. RESULTS: We investigated the carotenoid profile of tea flowers and determined changes in concentrations over the floral development. The flowers contained oxygenated xanthophylls such as neoxanthin, lutein and zeaxanthin, as well as the hydrocarbons ß-carotene and α-carotene. Flowers of the tea plant contain to vegetables comparable amounts of carotenoids. The content of 9'-cis-epoxycarotenoids, which serve as abscisic acid precursors, as well as changes in concentration of abscisic acid were studied. The concentrations of carotenoids decreased whereas the abscisic acid content increased over the floral development. Exogenously applied S-abscisic acid affected water uptake, flower opening and carotenoid accumulation. CONCLUSION: In summary, this paper reports, for the first time, the carotenoid profile and content of tea flowers. The study revealed that carotenoids in tea flowers are an interesting target in respect of possible applications of tea flower extracts as well as biological functions of abscisic acid during floral development.

Functional characterization of aromatic amino acid aminotransferase involved in 2-phenylethanol biosynthesis in isolated rose petal protoplasts.

In rose flowers, 2-phenylethanol (2PE) is biosynthesized from l-phenylalanine (l-Phe) via phenylacetaldehyde (PAld) by the actions of two enzymes, pyridoxal-5'-phosphate (PLP)-dependent aromatic amino acid decarboxylase (AADC) and phenylacetaldehyde reductase (PAR). We here report that Rosa 'Yves Piaget' aromatic amino acid aminotransferase produced phenylpyruvic acid (PPA) from l-Phe in isolated petal protoplasts. We have cloned three full length cDNAs (RyAAAT1-3) of aromatic amino acid aminotransferase families based on rose EST database and homology regions. The RyAAATs enzymes were heterogeneously expressed in Escherichia coli and characterized biochemically. The recombinant RyAAAT3 showed the highest activity toward l-Phe in comparison with l-tryptophan, l-tyrosine, d-Phe, glycine, and l-alanine, and showed 9.7-fold higher activity with l-Phe rather than PPA as a substrate. RyAAAT3 had an optimal activity at pH 9 and at 45-55°C with α-ketoglutaric acid, and was found to be a PLP dependent enzyme based on the inhibition test using Carbidopa, an inhibitor of PLP-dependent enzymes. The transcript of RyAAAT3 was expressed in flowers as well as other organs of R. 'Yves Piaget'. RNAi suppression of RyAAAT3 decreased 2PE production, revealing the involvement of RyAAAT3 in 2PE biosynthesis in rose protoplasts and indicating that rose protoplasts have potentially two different 2PE biosynthetic pathways, the AADC route and the new route via PPA from l-Phe.

Incidence, risk factors and outcomes of bronchiolitis obliterans after allogeneic stem cell transplantation.

Bronchiolitis obliterans (BO) after allogeneic stem cell transplantation (allo-SCT) is a late-onset, life-threatening respiratory complication that significantly reduces a patient's quality of life. We retrospectively analysed the incidence of and risk factors for BO in allo-SCT recipients. In 2087 patients who underwent allo-SCT between January 1994 and June 2005 and survived >90 days after transplantation, 57 patients developed BO with a 5-year cumulative incidence of 2.8%. The median time interval from transplantation to BO diagnosis was 335 days (range 83-907 days). The 5-year cumulative incidence of BO was 1.62% in bone marrow transplantation (BMT) from related donors, 3.83% in peripheral blood stem cell transplantation (PBSCT) from related donors (R-PBSCT), 2.91% in BMT from unrelated donors and 2.65% in unrelated cord blood transplantation. The incidence of BO after R-PBSCT was significantly higher than that after any other type of allo-SCT (p = 0.02). R-PBSCT (p = 0.019) and preceding chronic graft-versus-host disease (GVHD) (p < 0.001) were BO-associated risk factors. Overall 5-year survival of patients with BO from the time of diagnosis was 45.4%, significantly less than those without (77.5% from day 335, p < 0.001). R-PBSCT recipients with existent chronic GVHD have a high risk of developing BO, and need extensive care and repeated pulmonary function tests.

Functional characterization of rose phenylacetaldehyde reductase (PAR), an enzyme involved in the biosynthesis of the scent compound 2-phenylethanol.

2-Phenylethanol (2PE) is a prominent scent compound released from flowers of Damask roses (Rosa×damascena) and some hybrid roses (Rosa 'Hoh-Jun' and Rosa 'Yves Piaget'). 2PE is biosynthesized from l-phenylalanine (l-Phe) via the intermediate phenylacetaldehyde (PAld) by two key enzymes, aromatic amino acid decarboxylase (AADC) and phenylacetaldehyde reductase (PAR). Here we describe substrate specificity and cofactor preference in addition to molecular characterization of rose-PAR and recombinant PAR from R.×damascena. The deduced amino acid sequence of the full-length cDNA encoded a protein exhibiting 77% and 75% identity with Solanum lycopersicum PAR1 and 2, respectively. The transcripts of PAR were higher in petals than calyxes and leaves and peaking at the unfurling stage 4. Recombinant PAR and rose-PAR catalyzed reduction of PAld to 2PE using NADPH as the preferred cofactor. Reductase activity of rose-PAR and recombinant PAR were higher for aromatic and aliphatic aldehydes than for keto-carbonyl groups. Both PARs showed that (S)-[4-(2)H] NADPH was preferentially used over the (R)-[4-(2)H] isomer to give [1-(2)H]-2PE from PAld, indicating that PAR can be classified as short-chain dehydrogenase reductase (SDR).

[Second transplantation for graft failure after allogeneic hematopoietic stem cell transplantation--a retrospective survey by Kanto Study Group for Cell Therapy].

We retrospectively surveyed patients who received a second transplantation for graft failure (GF) after allogeneic hematopoietic stem cell transplantation (SCT) in hospitals participating in the Kanto Study Group for Cell Therapy. A second SCT was performed in 21 of 45 patients with primary GF and in 13 of 15 with secondary GF. The median time between the first and second SCT was 49 days (range, 18-1204 days). The diagnosis included 28 patients with hematologic malignancies and 6 with aplastic anemia. Non-myeloablative or reduced-intensity conditioning was performed in 30 patients. Cord blood was frequently used as the source of stem cells followed by related donor peripheral blood, and unrelated bone marrow. Engraftment was achieved in 23 patients (68%). Conditioning regimen including total body or total lymphoid irradiation, was significantly associated with a higher engraftment rate. Overall survival at 5 years in all patients who underwent second SCT was 34%. Prognostic factors for better survival after second SCT were a time to second SCT longer than 90 days, the performance status at second SCT with 0 or 1, and the administration of tacrolimus for GVHD prophylaxis. The major cause of death after second SCT was infection. Although the outcome of a second SCT for graft failure remains poor, these findings suggest that the selection of patients as well as transplant methods, such as conditioning and GVHD prophylaxis, may contribute to survival.

Elucidation of the biochemical pathway of 2-phenylethanol from shikimic acid using isolated protoplasts of rose flowers.

The isolated protoplasts of rose flowers were used to investigate the metabolic pathway in rose flower leading from shikimic acid or L-phenylalanine (L-Phe) to 2-phenylethanol (2PE), a dominant volatile compound in hybrid roses such as Rosa damascena Mill., R. 'Hoh-Jun', and R. 'Yves Piaget'. Deuterium-labeled L-Phe ([2H8]L-Phe) was supplied to the protoplasts isolated from R. 'Yves Piaget' petals. The volatile end products ([2Hn]-2PE, n=6-8) and their related intermediates ([2Hn]phenylacetaldehyde, n=6-8) were detected in the protoplasts by gas chromatography-mass spectrometry (GC-MS). In addition, we chemically synthesized [2,3,4,5,6-13C5]shikimic acid, a new stable isotopomer, to investigate the formation of 2PE from shikimic acid by GC-MS and nuclear magnetic resonance. We proposed the hypothetical biochemical pathway of 2PE from shikimic acid via chorismic acid, L-Phe, and phenylacetaldehyde. This protoplast system facilitates findings of metabolic intermediates and simplifies the complex branching biosynthetic pathways of floral scents to distinct individual events.

Purification and characterization of beta-glucosidase involved in the emission of 2-phenylethanol from rose flowers.

Beta-glucosidase was partially purified from Rosa 'Hoh-Jun' petals. The enzyme was highly specific for such beta-D-glucopyranosides as 2-phenylethyl beta-D-glucopyranoside. The optimal activity was observed at pH 6.0 and 35 degrees C. The enzymes were composed with two proteins (160 and 155 kDa) by blue native-PAGE, and were classified in a family 1 glucosidase based on LC-MS/MS analyses.

Production of 2-phenylethanol in roses as the dominant floral scent compound from L-phenylalanine by two key enzymes, a PLP-dependent decarboxylase and a phenylacetaldehyde reductase.

We investigated the biosynthetic pathway for 2-phenylethanol, the dominant floral scent compound in roses, using enzyme assays. L-[(2)H8] Phenylalanine was converted to [(2)H8] phenylacetaldehyde and [(2)H8]-2-phenylethanol by two enzymes derived from the flower petals of R. 'Hoh-Jun,' these being identified as pyridoxal-5'-phosphate-dependent L-aromatic amino acid decarboxylase (AADC) and phenylacetaldehyde reductase (PAR). The activity of rose petal AADC to yield phenylacetaldehyde was nine times higher toward L-phenylalanine than toward its D-isomer, and this conversion was not inhibited by iproniazid, a specific inhibitor of monoamine oxidase. Under aerobic conditions, rose petal AADC stoichiometrically produced NH3 together with phenylacetaldehyde during the course of decarboxylation and oxidation, followed by the hydrolysis of L-phenylalanine. Phenylacetaldehyde was subsequently converted to 2-phenylethanol by the action of PAR. PAR showed specificity toward several volatile aldehydes.