Essential role of the PSI-LHCII supercomplex in photosystem acclimation to light and/or heat conditions by state transitions

Light and temperature affect state transitions through changes in the plastoquinone (PQ) redox state in photosynthetic organisms. We demonstrated that light and/or heat treatment induced preferential photosystem (PS) I excitation by binding light-harvesting complex II (LHCII) proteins. The photosystem of wheat was in state 1 after dark overnight treatment, wherein PQ was oxidized and most of LHCII was not bound to PSI. At the onset of the light treatment [25 °C in the light (100 µmol photons m^-2 s^-1)], two major LHCIIs, Lhcb1 and Lhcb2 were phosphorylated, and the PSI-LHCII supercomplex formed within 5 min, which coincided with an increase in the PQ oxidation rate. Heat treatment at 40 °C of light-adapted wheat led to further LHCII protein phosphorylation of, resultant cyclic electron flow promotion, which was accompanied by ultrafast excitation of PSI and structural changes of thylakoid membranes, thereby protecting PSII from heat damage. These results suggest that LHCIIs are required for the functionality of wheat plant PSI, as it keeps PQ oxidized by regulating photochemical electron flow, thereby helping acclimation to environmental changes.

Two Cytochrome P450 Monooxygenases Catalyze Early Hydroxylation Steps in the Potato Steroid Glycoalkaloid Biosynthetic Pathway

α-Solanine and α-chaconine, steroidal glycoalkaloids (SGAs) found in potato (Solanum tuberosum), are among the best-known secondary metabolites in food crops. At low concentrations in potato tubers, SGAs are distasteful; however, at high concentrations, SGAs are harmful to humans and animals. Here, we show that POTATO GLYCOALKALOID BIOSYNTHESIS1 (PGA1) and PGA2, two genes that encode cytochrome P450 monooxygenases (CYP72A208 and CYP72A188), are involved in the SGA biosynthetic pathway, respectively. The knockdown plants of either PGA1 or PGA2 contained very little SGA, yet vegetative growth and tuber production were not affected. Analyzing metabolites that accumulated in the plants and produced by in vitro enzyme assays revealed that PGA1 and PGA2 catalyzed the 26- and 22-hydroxylation steps, respectively, in the SGA biosynthetic pathway. The PGA-knockdown plants had two unique phenotypic characteristics: The plants were sterile and tubers of these knockdown plants did not sprout during storage. Functional analyses of PGA1 and PGA2 have provided clues for controlling both potato glycoalkaloid biosynthesis and tuber sprouting, two traits that can significantly impact potato breeding and the industry.

Identification of (Z)-3:(E)-2-Hexenal Isomerases Essential to the Production of the Leaf Aldehyde in Plants

The green odor of plants is characterized by green leaf volatiles (GLVs) composed of C6 compounds. GLVs are biosynthesized from polyunsaturated fatty acids in thylakoid membranes by a series of enzymes. A representative member of GLVs (E)-2-hexenal, known as the leaf aldehyde, has been assumed to be produced by isomerization from (Z)-3-hexenal in the biosynthesis pathway; however, the enzyme has not yet been identified. In this study, we purified the (Z)-3:(E)-2-hexenal isomerase (HI) from paprika fruits and showed that various plant species have homologous HIs. Purified HI is a homotrimeric protein of 110 kDa composed of 35-kDa subunits and shows high activity at acidic and neutral pH values. Phylogenetic analysis showed that HIs belong to the cupin superfamily, and at least three catalytic amino acids (His, Lys, Tyr) are conserved in HIs of various plant species. Enzymatic isomerization of (Z)-3-hexenal in the presence of deuterium oxide resulted in the introduction of deuterium at the C4 position of (E)-2-hexenal, and a suicide substrate 3-hexyn-1-al inhibited HI irreversibly, suggesting that the catalytic mode of HI is a keto-enol tautomerism reaction mode mediated by a catalytic His residue. The gene expression of HIs in Solanaceae plants was enhanced in specific developmental stages and by wounding treatment. Transgenic tomato plants overexpressing paprika HI accumulated (E)-2-hexenal in contrast to wild-type tomato plants mainly accumulating (Z)-3-hexenal, suggesting that HI plays a key role in the production of (E)-2-hexenal in planta.

Abstract P1-10-26: Frozen glove could be a new hope for prevention of chemotherapy induced peripheral neuropathy

Introduction

Chemotherapy induced peripheral neuropathy (CIPN) is a major problem for patients who receive chemotherapy, and it sometimes deteriorate patients' QOL. Many CIPN prevention trials have been conducted, but no one succeeded to date.

Objectives

To investigate if frozen glove (FG) prevents peripheral neuropathy induced by nanoparticle albumin-bound paclitaxel (nab-PTX).

Methods

We conducted CIPN prevention study using FG, as part of multi-institutional phase II study which analyze efficacy and safety of nab-PTX (260mg/m2 q3w) followed by FEC (500/100/500 mg/m2, q3w) in pre-operative setting (KBCSG-TR 1213 trial). Each patient wore an FGs for a total of 60 minutes (15mins before and after nab-PTX treatment) on both hands. CIPN were assessed during treatment period with nab-PTX by the Patient Neurotoxicity Questionnaire (PNQ) and the FACT/GOG (Gynecologic Oncology Group) Neurotoxicity (Ntx) subscale. Patients were asked to access PNQ and FACT/GOG Ntx on a daily basis and recorded in the CIPN diary.

Results

Sixty two patients were registered for KBCSG-TR 1213 trial. And forty two pts (68%) who turned in the diary were analyzed. Median age and median body mass index (BMI) was 48 years old and 21.6 kg/m2, respectively. We analyzed following 6 categories, 1) symptoms of hands and arms, 2) symptoms of foots, 3) symptoms of general, 4) symptoms of ears 5) muscle weakness of hands and arms and 6) muscle weakness of foots. Median time to each event was 1) 25.5 days, 2) 5days, 3) 3days, 4) not available, 5) 46.5days, 6)4 days. By using FG, time to event of hands and arms was much longer compared with that of foots.

Conclusions

CIPN could be prevented or lessened by FG. Randomized phase II CIPN prevention study has been just launched.

Citation Format: Nakayama T, Yasojima H, Morimoto T, Yoshidome K, Mizutani M, Takashima T, Matsunami N, Enami A, Kagawa M, Nomura T, Shiba E, Nishi T, Kamigaki S, Kozuma Y, Yoshinami T, Masuda N. Frozen glove could be a new hope for prevention of chemotherapy induced peripheral neuropathy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-10-26.

Volatile Glycosylation in Tea Plants: Sequential Glycosylations for the Biosynthesis of Aroma β-Primeverosides Are Catalyzed by Two Camellia sinensis Glycosyltransferases

Tea plants (Camellia sinensis) store volatile organic compounds (VOCs; monoterpene, aromatic, and aliphatic alcohols) in the leaves in the form of water-soluble diglycosides, primarily as β-primeverosides (6-O-β-D-xylopyranosyl-β-D-glucopyranosides). These VOCs play a critical role in plant defenses and tea aroma quality, yet little is known about their biosynthesis and physiological roles in planta. Here, we identified two UDP-glycosyltransferases (UGTs) from C. sinensis, UGT85K11 (CsGT1) and UGT94P1 (CsGT2), converting VOCs into β-primeverosides by sequential glucosylation and xylosylation, respectively. CsGT1 exhibits a broad substrate specificity toward monoterpene, aromatic, and aliphatic alcohols to produce the respective glucosides. On the other hand, CsGT2 specifically catalyzes the xylosylation of the 6'-hydroxy group of the sugar moiety of geranyl β-D-glucopyranoside, producing geranyl β-primeveroside. Homology modeling, followed by site-directed mutagenesis of CsGT2, identified a unique isoleucine-141 residue playing a crucial role in sugar donor specificity toward UDP-xylose. The transcripts of both CsGTs were mainly expressed in young leaves, along with β-primeverosidase encoding a diglycoside-specific glycosidase. In conclusion, our findings reveal the mechanism of aroma β-primeveroside biosynthesis in C. sinensis. This information can be used to preserve tea aroma better during the manufacturing process and to investigate the mechanism of plant chemical defenses.

Reactive short-chain leaf volatiles act as powerful inducers of abiotic stress-related gene expression

Abiotic stresses cause serious damage to plants; therefore, plants undergo a complicated stress response through signal transduction originating from environmental stimuli. Here we show that a subset of short-chain leaf volatiles with an α, β-unsaturated carbonyl bond in their structure (reactive short-chain leaf volatiles, RSLVs) like (E)-2-hexenal and (E)-2-butenal can act as signal chemicals that strongly induce the gene expression of abiotic-related transcription factors, such as heat stress-related transcription factors (HSFA2, MBF1c) and other abiotic stress-related transcription factors (DREB2A, ZATs). RSLV-induced expression of HSFA2 and MBF1c was eliminated in HSFA1s-, known as heat stress response master regulators, knockout mutant, whereas those of DREB2A and ZATs were not, suggesting that the RSLV signaling pathway is composed of HSFA1-dependent and -independent pathways. RSLV treatment induced production of chaperon proteins, and the RSLV-treated Arabidopsis thus demonstrated enhanced abiotic stress tolerance. Because oxidative stress treatment enhanced RSLV production, we concluded that commonly found RSLVs produced by environmental stresses are powerful inducer of abiotic stress-related gene expression as oxidative stress signals.

Regulation of photochemical energy transfer accompanied by structural changes in thylakoid membranes of heat-stressed wheat

Photosystems of higher plants alleviate heat-induced damage in the presence of light under moderate stressed conditions; however, in the absence of light (i.e., in the dark), the same plants are damaged more easily. (Yamauchi and Kimura, 2011) We demonstrate that regulating photochemical energy transfer in heat-treated wheat at 40 °C with light contributed to heat tolerance of the photosystem. Chlorophyll fluorescence analysis using heat-stressed wheat seedlings in light showed increased non-photochemical quenching (NPQ) of chlorophyll fluorescence, which was due to thermal dissipation that was increased by state 1 to state 2 transition. Transmission electron microscopy revealed structural changes in thylakoid membranes, including unstacking of grana regions under heat stress in light. It was accompanied by the phosphorylation of thylakoid proteins such as D1 and D2 proteins and the light harvesting complex II proteins Lhcb1 and Lhcb2. These results suggest that heat stress at 40 °C in light induces state 1 to state 2 transition for the preferential excitation of photosystem I (PSI) by phosphorylating thylakoid proteins more strongly. Structural changes of thylakoid membrane also assist the remodeling of photosystems and regulation of energy distribution by transition toward state 2 probably contributes to plastoquione oxidation; thus, light-driven electrons flowing through PSI play a protective role against PSII damage under heat stress.

Heliolactone, a non-sesquiterpene lactone germination stimulant for root parasitic weeds from sunflower

Root exudates of sunflower (Helianthus annuus L.) line 2607A induced germination of seeds of root parasitic weeds Striga hermonthica, Orobanche cumana, Orobanche minor, Orobanche crenata, and Phelipanche aegyptiaca. Bioassay-guided purification led to the isolation of a germination stimulant designated as heliolactone. FT-MS analysis indicated a molecular formula of C20H24O6. Detailed NMR spectroscopic studies established a methylfuranone group, a common structural component of strigolactones connected to a methyl ester of a C14 carboxylic acid via an enol ether bridge. The cyclohexenone ring is identical to that of 3-oxo-α-ionol and the other part of the molecule corresponds to an oxidized carlactone at C-19. It is a carlactone-type molecule and functions as a germination stimulant for seeds of root parasitic weeds. Heliolactone induced seed germination of the above mentioned root parasitic weeds, while dehydrocostus lactone and costunolide, sesquiterpene lactones isolated from sunflower root exudates, were effective only on O. cumana and O. minor. Heliolactone production in aquacultures increased when sunflower seedlings were grown hydroponically in tap water and decreased on supplementation of the culture with either phosphorus or nitrogen. Costunolide, on the other hand, was detected at a higher concentration in well-nourished medium as opposed to nutrient-deficient media, thus suggesting a contrasting contribution of heliolactone and the sesquiterpene lactone to the germination of O. cumana under different soil fertility levels.

The Plasmodium berghei sexual stage antigen PSOP12 induces anti-malarial transmission blocking immunity both in vivo and in vitro

Anti-malarial transmission-blocking vaccines (TBVs) aim to inhibit the transmission of Plasmodium from humans to mosquitoes by targeting the sexual/ookinete stages of the parasite. Successful use of such interventions will subsequently result in reduced cases of malarial infection within a human population, leading to local elimination. There are currently only five lead TBV candidates under examination. There is a consequent need to identify novel antigens to allow the formulation of new potent TBVs. Here we describe the design and evaluation of a potential TBV (BDES-PbPSOP12) targeting Plasmodium berghei PSOP12 based on the baculovirus dual expression system (BDES), enabling expression of antigens on the surface of viral particles and within infected mammalian cells. In silico studies have previously suggested that PSOP12 (Putative Secreted Ookinete Protein 12) is expressed within the sexual stages of the parasite (gametocytes, gametes and ookinetes), and is a member of the previously characterized 6-Cys family of plasmodial proteins. We demonstrate that PSOP12 is expressed within the sexual/ookinete forms of the parasite, and that sera obtained from mice immunized with BDES-PbPSOP12 can recognize the surface of the male and female gametes, and the ookinete stages of the parasite. Immunization of mice with BDES-PbPSOP12 confers modest but significant transmission-blocking activity in vivo by active immunization (53.1% reduction in oocyst intensity, 10.9% reduction in oocyst prevalence). Further assessment of transmission-blocking potency ex vivo shows a dose-dependent response, with up to a 76.4% reduction in intensity and a 47.2% reduction in prevalence observed. Our data indicates that PSOP12 in Plasmodium spp. could be a potential new TBV target candidate, and that further experimentation to examine the protein within human malaria parasites would be logical.

Intraocular Ossification in the GSP/pe Chicken With Imperfect Albinism

The eyes of 2 male and 2 female GSP/pe chickens, the imperfect albino strain, were investigated at 52 weeks of age. Aged chickens of the GSP/pe colony became blind with bilateral ocular enlargement and opaque lenses. Affected eyes (bilateral in 2 males and unilateral in 2 females) were hard and difficult to section; histologic specimens were processed after decalcification. A large portion of the posterior chamber was occupied by cancellous bone containing fibrous and cartilaginous foci. Osseous tissues developed adjacent to the choroid, and no retinal pigment epithelium (RPE) was detected between osseous tissues and the choroid. Small segments of degenerate neuronal retina were scattered in the osseous tissue. The irises and ciliary bodies were deformed by osseous tissue, and the lenses had severe cataracts. These observations suggest that the intraocular osseous tissue may be derived from RPE in the hereditary incomplete-albino strain of chickens.

Cost-effective development of highly polymorphic microsatellite in Japanese quail facilitated by next-generation sequencing

Next-generation sequencing technologies permit rapid and cost-effective identification of numerous putative microsatellite loci. Here, from the genome sequences of Japanese quail, we developed microsatellite markers containing dinucleotide repeats and employed these for characterisation of genetic diversity and population structure. A total of 385 individuals from 12 experimental and one wild-derived Japanese quail lines were genotyped with newly developed autosomal markers. The maximum number of alleles, expected heterozygosity and polymorphic information content (PIC) per locus were 10, 0.80 and 0.77 respectively. Approximately half of the markers were highly informative (PIC ≥ 0.50). The mean number of alleles per locus and observed heterozygosity within a line were in the range of 1.3-4.1 and 0.11-0.53 respectively. Compared with the wild-derived line, genetic diversity levels were low in the experimental lines. Genetic differentiation (FST ) between all pairs of the lines ranged from 0.13 to 0.83. Genetic clustering analyses based on multilocus genotypes of individuals showed that most individuals formed clearly defined clusters corresponding to the origins of the lines. These results suggest that Japanese quail experimental lines are highly structured. Microsatellite markers developed in this study may be effective for future genetic studies of Japanese quail.

Biosynthetic Origin of the 1-Oxygen of Umbelliferone in the Root Tissue of Sweet Potato

Oxidation of p-coumarate at the ortho-position is a key step to form umbelliferone. A tracer analysis using 18O2 was performed in order to take information about the formation of umbelliferone in the root tissue of sweet potato. Mass fragmentation experiments revealed incorporation of an 18O atom into the 1-position of umbelliferone. This result indicates that the lactone of umbelliferone is formed via ortho-hydroxylation of the p-coumarate unit using O2.

A phase II study of metronomic paclitaxel/cyclophosphamide/capecitabine followed by 5-fluorouracil/epirubicin/cyclophosphamide as preoperative chemotherapy for triple-negative or low hormone receptor expressing/HER2-negative primary breast cancer

PURPOSE

Better treatments for triple-negative breast cancer (TNBC) are needed. To address this need, we studied the effects of preoperative metronomic paclitaxel/cyclophosphamide/capecitabine (mPCX) followed by 5-fluorouracil (FU)/epirubicin/cyclophosphamide (FEC) as preoperative chemotherapy in TNBC patients.

METHODS

Forty primary TNBC patients received four cycles of metronomic paclitaxel (80 mg/m(2) on Days 1, 8, and 15), cyclophosphamide (50 mg/body daily), and capecitabine (1,200 mg/m(2) daily), followed by four cycles of 5-FU (500 mg/m(2)), epirubicin (100 mg/m(2)), and cyclophosphamide (500 mg/m(2)) every 3 weeks. The primary end point was the pathological complete response (pCR) rate.

RESULTS

Forty patients formed the intent-to-treat population. The median dose intensities of paclitaxel, cyclophosphamide, and capecitabine were 89.7, 92.1, and 89.8%, respectively. Five patients discontinued mPCX and two discontinued FEC, primarily because of adverse events, resulting in a per-protocol population (PPS) of 33 patients. The pCR (ypT0/Tis ypN0) rate was 47.5% (19/40) in the intent-to-treat population and 54.5% (18/33) in the PPS. The clinical response rates were 36/40 (90.0%) and 31/33 (93.9%) in the intent-to-treat and PPS, respectively. The breast conservation rate was 72.7% (24/33), and 5/13 patients underwent partial resection instead of pre-planned total mastectomy. Grade 3-4 adverse events included neutropenia (35%), leukopenia (25%), and hand-foot syndrome (8%).

CONCLUSIONS

Metronomic PCX followed by FEC chemotherapy was associated with a high pCR rate and low toxicity in TNBC patients. Further studies of this regimen in larger numbers of patients are warranted.

A Plant Growth Retardant, Uniconazole, Is a Potent Inhibitor of ABA Catabolism inArabidopsis

Plant growth retardants (PGRs) reduce the shoot growth of plants by inhibiting gibberellin biosynthesis. In this study, we performed detailed analyses of the inhibitory effects of PGRs on Arabidopsis abscisic acid (ABA) 8'-hydroxylase, a major ABA catabolic enzyme, recently identified as CYP707As. In an in vitro assay with CYP707A3 microsomes expressed in insect cells, uniconazole-P inhibited CYP707A3 activity more effectively than paclobutrazol or tetcyclacis, whereas the other PGRs tested did not inhibit it significantly. Uniconazole-P was found to be a strong competitive inhibitor (K(i)=8.0 nM) of ABA 8'-hydroxylase. Uniconazole-P-treated Arabidopsis plants showed enhanced drought tolerance. In uniconazole-P-treated plants, endogenous ABA levels increased 2-fold as compared with the control, and co-application of GA(4) did not suppress the effects, indicating that the effects were not due to gibberellin deficiency. Thus uniconazole-P effectively inhibits ABA catabolism in Arabidopsis plants. We also discuss the structure-activity relationship of the azole-type compounds on ABA 8'-hydroxylase inhibitory activity.

Comparison of microsatellite variations between Red Junglefowl and a commercial chicken gene pool

It is assumed that Red Junglefowl (Gallus gallus) is one of the main ancestors of domestic chickens (Gallus gallus domesticus). Differences in microsatellite polymorphisms between Red Junglefowl and modern commercial chickens, which are used for egg and meat production, have not been fully reported. A total of 361 individuals from 1 Red Junglefowl population that has been maintained as a closed flock, 5 final cross-bred commercial layer populations (white-, tinted-, and brown-egg layers), and 2 final cross-bred commercial broiler populations were genotyped for 40 autosomal microsatellite loci. We compared microsatellite variations in Red Junglefowl with those in a commercial chicken gene pool. The contribution of each population to the genetic diversity was also estimated based on the molecular coancestry. In total, 302 distinct alleles were detected in 1 Red Junglefowl and 7 commercial chicken populations, of which 31 alleles (10.3%) were unique to Red Junglefowl, most of which occurred at a high frequency. The genetic differentiation between Red Junglefowl and commercial chickens (pairwise FST) ranged from 0.32 to 0.47. According to the neighbor-joining tree based on the modified Cavalli-Sforza chord distances and the Bayesian clustering analysis, Red Junglefowl was genetically distant from the commercial chicken gene pool tested. In all of the populations analyzed, Red Junglefowl made the highest contribution to genetic diversity. These results suggest that Red Junglefowl has a distinct distribution of microsatellite alleles and that there is a high level of genetic divergence between Red Junglefowl and commercial chickens.

Crystal structures of β-primeverosidase in complex with disaccharide amidine inhibitors

β-Primeverosidase (PD) is a disaccharide-specific β-glycosidase in tea leaves. This enzyme is involved in aroma formation during the manufacturing process of oolong tea and black tea. PD hydrolyzes β-primeveroside (6-O-β-d-xylopyranosyl-β-d-glucopyranoside) at the β-glycosidic bond of primeverose to aglycone, and releases aromatic alcoholic volatiles of aglycones. PD only accepts primeverose as the glycone substrate, but broadly accepts various aglycones, including 2-phenylethanol, benzyl alcohol, linalool, and geraniol. We determined the crystal structure of PD complexes using highly specific disaccharide amidine inhibitors, N-β-primeverosylamidines, and revealed the architecture of the active site responsible for substrate specificity. We identified three subsites in the active site: subsite -2 specific for 6-O-β-d-xylopyranosyl, subsite -1 well conserved among β-glucosidases and specific for β-d-glucopyranosyl, and wide subsite +1 for hydrophobic aglycone. Glu-470, Ser-473, and Gln-477 act as the specific hydrogen bond donors for 6-O-β-d-xylopyranosyl in subsite -2. On the other hand, subsite +1 was a large hydrophobic cavity that accommodates various aromatic aglycones. Compared with aglycone-specific β-glucosidases of the glycoside hydrolase family 1, PD lacks the Trp crucial for aglycone recognition, and the resultant large cavity accepts aglycone and 6-O-β-d-xylopyranosyl together. PD recognizes the β-primeverosides in subsites -1 and -2 by hydrogen bonds, whereas the large subsite +1 loosely accommodates various aglycones. The glycone-specific activity of PD for broad aglycone substrates results in selective and multiple release of temporally stored alcoholic volatile aglycones of β-primeveroside.

Evolution and diversity of the 2-oxoglutarate-dependent dioxygenase superfamily in plants

The 2-oxoglutarate-dependent dioxygenase (2OGD) superfamily is the second largest enzyme family in the plant genome, and its members are involved in various oxygenation/hydroxylation reactions. Despite their biochemical significance in metabolism, a systematic analysis of plant 2OGDs remains to be accomplished. We present a phylogenetic classification of 479 2OGDs in six plant models, ranging from green algae to angiosperms. These were classified into three classes - DOXA, DOXB and DOXC - based on amino acid sequence similarity. The DOXA class includes plant homologs of Escherichia coli AlkB, which is a prototype of 2OGD involved in the oxidative demethylation of alkylated nucleic acids and histones. The DOXB class is conserved across all plant taxa and is involved in proline 4-hydroxylation in cell wall protein synthesis. The DOXC class is involved in specialized metabolism of various phytochemicals, including phytohormones and flavonoids. The vast majority of 2OGDs from land plants were classified into the DOXC class, but only seven from Chlamydomonas, suggesting that this class has diversified during land plant evolution. Phylogenetic analysis assigned DOXC-class 2OGDs to 57 phylogenetic clades. 2OGD genes involved in gibberellin biosynthesis were conserved among vascular plants, and those involved in flavonoid and ethylene biosynthesis were shared among seed plants. Several angiosperm-specific clades were found to be involved in various lineage-specific specialized metabolisms, but 31 of the 57 DOXC-class clades were only found in a single species. Therefore, the evolution and diversification of DOXC-class 2OGDs is partly responsible for the diversity and complexity of specialized metabolites in land plants.

Abstract P3-14-05: Randomized phase II study of preoperative docetaxel and cyclophosphamide-containing chemotherapy for luminal-type breast cancer

Background: We compared and evaluated three 6-cycle, docetaxel and cyclophosphamide (TC)-containing chemotherapy regimens in a multicenter randomized phase II study. The main aim was to investigate whether anthracyclines are needed or can be omitted, and whether the order of chemotherapy is important, for treating luminal-type breast cancer.

Methods: We recruited patients (pts) with ER-positive, HER2-negative breast cancer aged 20–70 years, and histo-pathologically invasive breast cancer (T1c-3, N0-1, M0), T≤7cm. Pts were randomized to 3 groups for the following treatments: 6 cycles of TC; 3 cycles of 5-FU/epirubicin/cyclophosphamide (FEC) followed by 3 cycles of TC (FEC-TC); and 3 cycles of TC followed by 3 cycles of FEC (TC-FEC). TC treatment consisted of administration of docetaxel at 75 mg/m2 and cyclophosphamide at 600 mg/m2 once every 3 weeks. FEC treatment consisted of administration of 5-FU at 500 mg/m2, epirubicin at 100 mg/m2, and cyclophosphamide at 500 mg/m2 once every 3 weeks. We aimed to enroll 65 pts per group based on an expected pCR rate among regimens of adding 10% at a threshold of 9%. The primary endpoint was pathological complete response (pCR) rate. Secondary endpoints were overall response rate (ORR), breast conservation rate and safety.

Results: A total of 195 pts (median age, 49.5 years (range, 26–69); median tumor size, 32.8 mm (range, 9–82); 91 pts with N(+) (51%)) were enrolled and randomized as follows: FEC-TC (n = 65), TC-FEC (n = 63), and TC group (n = 67). There were no differences in backgrounds among groups. Both the intention-to-treat population and the safety analysis set included 65, 63 and 65 pts in these groups, respectively. The 6-cycle treatment completion rates were 96.9%, 96.8% and 84.6%, respectively. pCR, defined as yT0/isyN0, was achieved by 9.2% of pts in the FEC-TC group, 8.1% in the TC-FEC group, and 15.9% in the TC group (p = 0.321). A quasi pCR in breast (yT0/is and near pCR) was achieved by 13.9%, 14.5%, and 17.5%, respectively. These responses did not differ among the 3 groups. ORRs, assessed by MRI or CT, were 75.8% (CR: 12.9%), 75% (CR: 5%), and 82.2% (CR: 17.9%) in the FEC-TC, TC-FEC and TC groups, respectively. Breast conservation rates were 50.8%, 45.2%, and 73.0%, respectively.Adverse events of Grade≥3 were observed in 20.0%, 27.0%, and 20.3% of pts in the FEC-TC, TC-FEC, and TC groups, respectively, with no significant differences. Febrile neutropenia was observed in 17.2%, 21.0%, and 11.3%, respectively, but in most cases it was managed sufficiently on an outpatient basis. Of 28, 27 and 23 pts in these groups in whom mastectomy was planned, 9 (32%), 5 (19%), and 10 (44%) were successfully converted to undergo breast-conserving surgery. Of 37, 35 and 40 pts in the FEC-TC, TC-FEC and TC groups in whom breast-conserving surgery was planned, 13 (35%), 12 (34%), and 4 (10%) underwent mastectomy.

Conclusion: Six cycles of TC had therapeutic effects and safety equivalent to FEC-TC and TC-FEC. The 3 treatment groups showed similar pCR rates, although the breast conservation rate was significantly higher in the TC group than in the other 2 groups. It may be possible to conduct preoperative chemotherapy for pts with ER-positive breast cancer without using an anthracycline.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-14-05.

The bioconversion of 5-deoxystrigol to sorgomol by the sorghum, Sorghum bicolor (L.) Moench

Strigolactones, important rhizosphere signalling molecules and a class of phytohormones that control shoot architecture, are apocarotenoids of plant origin. They have a structural core consisting of a tricyclic lactone connected to a butyrolactone group via an enol ether bridge. Deuterium-labelled 5-deoxystrigol stereoisomers were administered to aquacultures of a high sorgomol-producing sorghum cultivar, Sorghum bicolor (L.) Moench, and conversion of these substrates to sorgomol stereoisomers was investigated. Liquid chromatography-mass spectrometry analyses established that 5-deoxystrigol (5-DS) and ent-2'-epi-5-deoxystrigol were absorbed by sorghum roots, converted to sorgomol and ent-2'-epi-sorgomol, respectively, and exuded out of the roots. The conversion was inhibited by uniconazole-P, implying the involvement of cytochrome P450 in the hydroxylation. These results provide experimental evidence for the postulated biogenetic scheme for formation of strigolactones, in which hydroxylation at C-9 of 5-DS can generate sorgomol.