Temperature Control of the Self-Assembly Process of 4-Aminoquinoline Amphiphile: Selective Construction of Perforated Vesicles and Nanofibers, and Structural Restoration Capability

The construction of diverse and distinctive self-assembled structures in water, based on the control of the self-assembly processes of artificial small molecules, has received considerable attention in supramolecular chemistry. Cage-like perforated vesicles are distinctive and interesting self-assembled structures. However, the development of self-assembling molecules that can easily form perforated vesicles remains challenging. This paper reports a lower critical solution temperature (LCST) behavior-triggered self-assembly property of a 4-aminoquinoline (4-AQ)-based amphiphile with a tetra(ethylene glycol) chain, in HEPES buffer (pH 7.4). This property allows to form perforated vesicles after heating at 80 °C (> LCST). The self-assembly process of the 4-AQ amphiphile can be controlled by heating at 80 °C (> LCST) or 60 °C (< LCST). After cooling to room temperature, the selective construction of the perforated vesicles and nanofibers was achieved from the same 4-AQ amphiphile. Furthermore, the perforated vesicles exhibited slow morphological transformation into intertwined-like nanofibers but were easily restored by brief heating above the LCST.

Design and Synthesis of Poly(2,2'-Bipyridyl) Ligands for Induction of Cell Death in Cancer Cells: Control of Anticancer Activity by Complexation/Decomplexation with Biorelevant Metal Cations

Chelation therapy is a medical procedure for removing toxic metals from human organs and tissues and for the treatment of diseases by using metal-chelating agents. For example, iron chelation therapy is designed not only for the treatment of metal poisoning but also for some diseases that are induced by iron overload, cancer chemotherapy, and related diseases. However, the use of such metal chelators needs to be generally carried out very carefully, because of the side effects possibly due to the non-specific complexation with intracellular metal cations. Herein, we report on the preparation and characterization of some new poly(bpy) ligands (bpy: 2,2'-bipyridyl) that contain one-three bpy ligand moieties and their anticancer activity against Jurkat, MOLT-4, U937, HeLa S3, and A549 cell lines. The results of MTT assays revealed that the tris(bpy) and bis(bpy) ligands exhibit potent activity for inducing the cell death in cancer cells. Mechanistic studies suggest that the main pathway responsible for the cell death by these poly(bpy) ligands is apoptotic cell death. It was also found that the anticancer activity of the poly(bpy) ligands could be controlled by the complexation (anticancer activity is turned OFF) and decomplexation (anticancer activity is turned ON) with biorelevant metal cations. In this paper, these results will be described.

Control of the stepwise self-assembly process of a pH-responsive amphiphilic 4-aminoquinoline-tetraphenylethene conjugate

Controlling the kinetic processes of self-assembly and switching their kinetic properties according to the changes in external environments are crucial concepts in the field of supramolecular polymers in water for biological and biomedical applications. Here we report a new self-assembling amphiphilic 4-aminoquinoline (4-AQ)-tetraphenylethene (TPE) conjugate that exhibits kinetically controllable stepwise self-assembly and has the ability of switching its kinetic nature in response to pH. The self-assembly process of the 4-AQ amphiphile comprises the formation of sphere-like nanoparticles, a transition to short nanofibers, and their growth to long nanofibers with ∼1 μm length scale at room temperature (RT). The timescale of the self-assembly process differs according to the pH-responsivity of the 4-AQ moiety in a weakly acidic to neutral pH range. Therefore, after aging for 24 h at RT, the 4-AQ amphiphile forms metastable short nanofibers at pH 5.5, while it forms thermodynamically favored long nanofibers at pH 7.4. Moreover, the modulation of nanofiber growth proceeding spontaneously at RT was achieved by switching the kinetic pathway through changing the pH between 7.4 and 5.5.

Post-complexation Functionalization of Cyclometalated Iridium(III) Complexes and Applications to Biomedical and Material Sciences

Cyclometalated iridium(III) (Ir(III)) complexes exhibit excellent photophysical properties that include large Stokes shift, high emission quantum yields, and microsecond-order emission lifetimes, due to low-lying metal-to-ligand charge transfer (spin-forbidden singlet-triplet (³MLCT) transition). As a result, analogs have been applied for research not only in the material sciences, such as the development of organic light-emitting diodes (OLEDs), but also for photocatalysts, bioimaging probes, and anticancer reagents. Although a variety of methods for the synthesis and the applications of functionalized cyclometalated iridium complexes have been reported, functional groups are generally introduced to the ligands prior to the complexation with Ir salts. Therefore, it is difficult to introduce thermally unstable functional groups such as peptides and sugars due to the harsh reaction conditions such as the high temperatures used in the complexation with Ir salts. In this review, the functionalization of Ir complexes after the formation of cyclometalated Ir complexes and their biological and material applications are described. These methods are referred to as "post-complexation functionalization (PCF)." In this review, applications of PCF to the design and synthesis of Ir(III) complexes that exhibit blue -red and white color emissions, luminescence pH probes, luminescent probes of cancer cells, compounds that induce cell death in cancer cells, and luminescent complexes that have long emission lifetimes are summarized.

Detection of human coronavirus RNA in surgical smoke generated by surgical devices

BACKGROUND

Gaseous by-products generated by surgical devices - collectively referred to as 'surgical smoke' - present the hazard of transmitting infective viruses from patients to surgical teams. However, insufficient evidence exists to evaluate and mitigate the risks of SARS-CoV-2 transmission via surgical smoke.

AIM

To demonstrate the existence and infectivity of human coronavirus RNA in surgical smoke using a model experiment and to evaluate the possibility of lowering transmission risk by filtration through a surgical mask.

METHODS

Pelleted HeLa-ACE2-TMPRSS2 cells infected with human coronavirus were incised by electric scalpel and ultrasonic scalpel, separately. A vacuum system was used to obtain surgical smoke in the form of hydrosol. Reverse transcription-quantitative polymerase chain reaction was used to analyse samples for the presence of viral RNA, and infectivity was determined through plaque assay. Furthermore, a surgical mask was placed centrally in the vacuum line to evaluate its ability to filter viral RNA present in the surgical smoke.

FINDINGS

In this model, 1/10⁶ to 1/10⁵ of the viral RNA contained in the incision target was detected in the collected surgical smoke. The virus present in the smoke was unable to induce plaque formation in cultured cells. In addition, filtration of surgical smoke through a surgical mask effectively reduced the amount of viral RNA by at least 99.80%.

CONCLUSION

This study demonstrated that surgical smoke may carry human coronavirus, though viral infectivity was considerably reduced. In clinical settings, surgical mask filtration should provide sufficient additional protection against potential coronavirus, including SARS-CoV-2, infection facilitated by surgical smoke.

Structure-Based Identification of Potent Lysine-Specific Demethylase 1 Inhibitor Peptides and Temporary Cyclization to Enhance Proteolytic Stability and Cell Growth-Inhibitory Activity

Peptides are attractive drug candidates, but their utility is greatly limited by their inherent susceptibility to proteolytic degradation and their inability to pass through the cell membrane. Here, we employ a strategy of temporary cyclization to develop a cell-active lysine-specific demethylase 1 (LSD1/KDM1A) inhibitor peptide. We first identified a highly potent LSD1-inhibitory linear peptide, with the assistance of X-ray crystal structure data of inhibitor peptide-bound LSD1·CoREST. The peptide was converted to a redox-activatable cyclic peptide incorporating cell-penetrating peptide (CPP), expecting selective activation under intracellular reducing conditions. The cyclic peptide moiety exhibited enhanced stability to protease and was converted to the linear, unmodified LSD1 inhibitor peptide under reducing conditions. The cyclic peptide with CPP inhibited the proliferation of human acute myeloid leukemia cells (HL-60) in the low micromolar concentration range.

Fluorescence Response and Self-Assembly of a Tweezer-Type Synthetic Receptor Triggered by Complexation with Heme and Its Catabolites

There is increasing interest in the development and applications of synthetic receptors that recognize target biomolecules in aqueous media. We have developed a new tweezer-type synthetic receptor that gives a significant fluorescence response upon complexation with heme in aqueous solution at pH 7.4. The synthetic receptor consists of a tweezer-type heme recognition site and sulfo-Cy5 as a hydrophilic fluorophore. The receptor-heme complex exhibits a supramolecular amphiphilic character that facilitates the formation of self-assembled aggregates, and both the tweezer moiety and the sulfo-Cy5 moiety are important for this property. The synthetic receptor also exhibits significant fluorescence responses to biliverdin and bilirubin, but shows very weak fluorescence responses to flavin mononucleotide, folic acid, and nicotinamide adenine dinucleotide, which contain smaller π-scaffolds.

Methylene chain ruler for evaluating the regioselectivity of a substrate-recognising oxidation catalyst

Regioselective C-H oxidation of aliphatic molecules with synthetic catalysts is challenging. We incorporated substrate-recognition sites into a ruthenium porphyrin-heteroaromatic N-oxide catalytic system in order to characterise its regioselectivity for the oxidation of alkanes. This substrate-recognition catalytic reaction exhibits high regioselectivity and high reaction efficiency.

Catalytic Hydrolysis of Phosphate Monoester by Supramolecular Complexes Formed by the Self-Assembly of a Hydrophobic Bis(Zn2+-cyclen) Complex, Copper, and Barbital Units That Are Functionalized with Amino Acids in a Two-Phase Solvent System

We previously reported on the preparation of supramolecular complexes by the 2:2:2 assembly of a dinuclear Zn²⁺-cyclen (cyclen = 1,4,7,10-tetraazacyclododecane) complex having a 2,2′-bipyridyl linker equipped with 0~2 long alkyl chains (Zn₂L¹~Zn₂L³), 5,5-diethylbarbituric acid (Bar) derivatives, and a copper(II) ion (Cu²⁺) in aqueous solution and two-phase solvent systems and their phosphatase activities for the hydrolysis of mono(4-nitrophenyl) phosphate (MNP). These supermolecules contain Cu₂(μ-OH)₂ core that mimics the active site of alkaline phosphatase (AP), and one of the ethyl groups of the barbital moiety is located in close proximity to the Cu₂(μ-OH)₂ core. The generally accepted knowledge that the amino acids around the metal center in the active site of AP play important roles in its hydrolytic activity inspired us to modify the side chain of Bar with various functional groups in an attempt to mimic the active site of AP in the artificial system, especially in two-phase solvent system. In this paper, we report on the design and synthesis of new supramolecular complexes that are prepared by the combined use of bis(Zn²⁺-cyclen) complexes (Zn₂L¹, Zn₂L², and Zn₂L³), Cu²⁺, and Bar derivatives containing amino acid residues. We present successful formation of these artificial AP mimics with respect to the kinetics of the MNP hydrolysis obeying Michaelis–Menten scheme in aqueous solution and a two-phase solvent system and to the mode of the product inhibition by inorganic phosphate.

Stable Iron Porphyrin Intramolecularly Coordinated by Alcoholate Anion: Synthesis and Evaluation of Axial Ligand Effect of Alcoholate on Spectroscopy and Catalytic Activity

We synthesized intramolecularly aliphatic alcoholate-coordinated iron porphyrins (1a, 1b) that retain their axial coordination in the presence of another ligand or oxidant. The electron-donative character of alcoholate was less than that of thiolate, and the coordination ability of a sixth ligand to 1a and 1b was very much lower than in the case of the thiolate-coordinated compounds. Density functional theory calculations indicated that the marked difference in coordination ability could be explained in terms of thermodynamic and steric factors. The catalytic oxidizing ability of the thiolate-coordinated compound, SR complex, was much higher than that of 1a.

Effect of the o-Acetamido Group on pH-Dependent Light Emission of a 3-Hydroxyphenyl-Substituted Dioxetane Luminophore

A pioneering chemiluminescent molecule reported by Schaap and co-workers, 3-(2'-spiroadamantane)-4-methoxy-4-(3″-hydroxy)phenyl-1,2-dioxetane (AMPD), does not require enzymatic activation but is unsuitable for use under physiological conditions. To overcome this limitation, we have developed a new AMPD derivative that contains an acetamido group at the ortho position of the hydroxy group as an intramolecular hydrogen-bonding site in order to lower the p K_a value. This compound exhibits a superior chemiluminescence response to AMPD in the physiologically relevant pH range.

Abstract P5-07-07: The immune microenvironment of ductal carcinoma in situ of the breast

Background: The importance of tumor-infiltrating lymphocytes (TIL) in invasive breast carcinoma for tumor development and therapeutic response is widely accepted. However, the immune microenvironment of breast ductal carcinoma in situ (DCIS) has not been fully elucidated. Evasion of immune surveillance is a necessary step in tumor evolution. In DCIS, the tumor cells are relatively protected from the immune system due to an myoepithelial cell layer and basement membrane, and intraductal immune cells are rarely detected. In contrast, in invasive disease, cancer cells and immune cells are often intermingled. Thus, understanding the immune microenviroment of in situ to invasive carcinoma transition might be particularly important to identify novel targets for early stage of tumor invasion.

Aims: The aim of this study is to evaluate the clinical importance of TILs in DCIS.

Methods: TILs were assessed in 133 DCIS samples with or without microinvasive disease according to the proposed method from the International Immuno-Oncology Working Group on Breast Cancer. In addition, the relationship between TILs in DCIS and clinicopathological features was evaluated.

Results: TILs are present in most DCIS in varying levels. The median proportion of TILs in DCIS was 14%. Only a minority of DCIS showed &gt;50% TILs, which represented only 12.8% of all cases. High TILs in DCIS was significantly associated with comedo necrosis (p&lt;0.0001), high nuclear grade (p=0.0030), ER negativity (p&lt;0.0001), PR negativity (p&lt;0.0001), HER2 positivity (p=0.0030). Triple negative DCIS and HER2 positive DCIS had significantly higher level of TILs (p=0.0008). No correlation was demonstrated between TILs and recurrence risk.

Conclusions: High TILs in DCIS was significantly associated with adverse histopathologic features. Further characterization of immune environment of DCIS may be essential for immunotherapy and breast cancer prevention.

Citation Format: Yamashita N, Hisamatsu Y, Shigechi T, Tokunaga E, Saeki H, Oki E, Maehara Y. The immune microenvironment of ductal carcinoma in situ of the breast [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-07-07.

Inhibition of FAD-dependent lysine-specific demethylases by chiral polyamine analogues

Lysine-specific demethylases 1 and 2 (LSD1 and LSD2) are flavoenzyme demethylases, and their inhibitors are considered as potential chemical tools and anticancer agents. Here we report polyamine-based inhibitors of LSD1 and LSD2. In the initial screening, partially constrained polyamine 2 which contains three trans-cyclopentane units with a total of six stereogenic centers, showed the most potent LSD1-inhibitory activity. We then prepared a set of optical isomers of 2 and evaluated their inhibitory activities toward LSD1, LSD2, monoamine oxidases A and B (MAO-A and MAO-B). Optical isomers of 2 showed LSD1-inhibitory activity with K _i values of 2.2 to 6.4 μM, and LSD2-inhibitory activity with K _i values of 4.4 to 39 μM; there was a general preference for LSD1 to LSD2. All of them showed weak to negligible inhibition of MAO-A and MAO-B. This selectivity seemed to reflect the differences in the size and shape of the catalytic cavity of target enzymes, and our strategy of employing a set of optical isomers appears to be an effective approach for exploring the structural features of this family of enzymes. Polyamine 9 showed most potent LSD1-inhibitory activity (K _i = 2.2 μM in vitro), and it also inhibited the proliferation of HL-60 cells (IC₅₀ = 49 μM). On the other hand, 12 was the most potent inhibitors of LSD2 with in vitro K _i values of 4.4 μM.

Design and synthesis of a 4-aminoquinoline-based molecular tweezer that recognizes protoporphyrin IX and iron(iii) protoporphyrin IX and its application as a supramolecular photosensitizer

We report on the design and synthesis of a new type of 4-aminoquinoline-based molecular tweezer 1 which forms a stable host-guest complex with protoporphyrin IX (PPIX) via multiple interactions in a DMSO and HEPES buffer (pH 7.4) mixed solvent system. The binding constant for the 1 : 1 complex (K 11) between 1 and PPIX is determined to be 4 × 106 M-1. Furthermore, 1 also forms a more stable complex with iron(iii) protoporphyrin IX (Fe(iii)PPIX), the K 11 value for which is one order of magnitude greater than that for PPIX, indicating that 1 could be used as a recognition unit of a synthetic heme sensor. On the other hand, the formation of the stable PPIX·1 complex (supramolecular photosensitizer) prompted us to apply it to photodynamic therapy (PDT). Cell staining experiments using the supramolecular photosensitizer and evaluations of its photocytotoxicity indicate that the PDT activity of PPIX is improved as the result of the formation of a complex with 1.

Potent Antimalarial Activity of Two Arenes Linked with Triamine Designed To Have Multiple Interactions with Heme

Based on the idea that compounds designed to exhibit high affinity for heme would block hemozoin formation, a critical heme-detoxification process for malarial parasites, we synthesized a series of compounds with two π-conjugated moieties at terminal amino groups of triamine. These compounds exhibited moderate to high antimalarial activities in vitro toward both chloroquine-sensitive and chloroquine-resistant Plasmodium falciparum. In a P. berghei-infected mouse model, 3a and 12a showed potent antimalarial activities compared to artesunate, as well as a prolonged duration of antimalarial effect. We found a good correlation between protective activity against hemin degradation and antimalarial activity. Compounds 8b and 3a strongly inhibited hemozoin formation catalyzed by heme detoxification protein.

Design and synthesis of a luminescent iridium complex-peptide hybrid (IPH) that detects cancer cells and induces their apoptosis

Tumor necrosis factor related apoptosis inducing ligand (TRAIL) triggers the cell-extrinsic apoptosis pathway by complexation with its signaling receptors such as death receptors (DR4 and DR5). TRAIL is a C₃-symmetric type II transmembrane protein, consists of three monomeric units. Cyclometalated iridium(III) complexes such as fac-Ir(tpy)₃ (tpy = 2-(4-tolyl)pyridine) also possess a C₃-symmetric structure and are known to have excellent luminescence properties. In this study, we report on the design and synthesis of a C₃-symmetric and luminescent Ir complex-peptide hybrid (IPH), which contains a cyclic peptide that had been reported to bind to death receptor (DR5). The results of MTT assay of Jurkat, K562 and Molt-4 cells with IPH and co-staining experiments with IPH and an anti-DR5 antibody indicate that IPH binds to DR5 and induces apoptosis in a manner parallel to the DR5 expression level. Mechanistic studies of cell death suggest that apoptosis and necrosis-like cell death are differentiated by the position of the hydrophilic part that connects Ir complex and the peptide units. These findings suggest that IPHs could be a promising tool for controlling apoptosis and necrosis by activation of the extra-and intracellular cell death pathway and to develop new anticancer drugs that detect cancer cells and induce their cell death.

A phase I study of binimetinib (MEK162) in Japanese patients with advanced solid tumors

PURPOSE

Binimetinib is a potent, selective MEK1/2 inhibitor with demonstrated efficacy against BRAF- and RAS-mutant tumors. Retinal adverse events associated with MEK inhibitors have been reported in some cases. The aim of this study was to assess single-agent binimetinib, with detailed ophthalmologic monitoring, in Japanese patients with advanced solid tumors.

METHODS

This was an open-label phase I dose-escalation and dose-expansion study (NCT01469130). Adult patients with histologically confirmed, evaluable, advanced solid tumors were enrolled and treated with binimetinib 30 or 45 mg twice daily (BID). The primary objective was to determine the maximum tolerated dose (MTD) and/or recommended phase II dose (RP2D) of single-agent binimetinib in Japanese patients.

RESULTS

Twenty-one patients were enrolled; 3 and 8 patients had documented BRAF and KRAS mutations, respectively. Two of 6 patients (33 %) receiving binimetinib 45 mg BID in dose-escalation experienced recurrent grade 2 retinal adverse events (AEs) which were reversible, and this dose was declared the MTD and RP2D. All patients experienced ≥1 AE suspected to be treatment related; the most common (>50 %) were blood creatine phosphokinase increase (76 %), retinal detachment and aspartate aminotransferase increase (62 % each), and diarrhea (52 %). There were no complete or partial responses; 14 patients (67 %) had stable disease, which lasted >180 days in 5 patients. Expression of phospho-ERK decreased in the skin following binimetinib treatment at both dose levels, indicating target inhibition.

CONCLUSIONS

Binimetinib demonstrated efficacy and acceptable safety in Japanese patients with solid tumors, supporting the 45 mg BID dose of binimetinib as the RP2D.

Synthesis and photochemical properties of pH responsive tris-cyclometalated iridium(III) complexes that contain a pyridine ring on the 2-phenylpyridine ligand

In our previous publication, it was reported that fac-Ir(atpy)3 3 (atpy = 2-(5'-amino-4'-tolyl)pyridine), which contains three amino groups at the 5'-position of the atpy ligands, exhibits a pH-dependent change in the color of the emitted radiation. Aqueous solution of 3 shows a weak red emission (at around 613 nm) under neutral or basic conditions, but the emission color changes to green (at around 530 nm) under acidic conditions, where the NH2 group is protonated to become an electron-withdrawing (NH3)(+) group. In this manuscript, we report on the preparation of some new pH-responsive Ir(III) complexes; fac-Ir(4Pyppy)3 5 and fac-Ir(3Pyppy)3 6 that contain three pyridyl groups at the 5'-position of the 2-phenylpyridine (ppy) ligand, and Ir(4Pyppym)3 7 and Ir(3Pyppym)3 8 that contain a pyridyl group at the same position of the 2-phenylpyrimidine (ppym) ligand. The introduction of three pyridyl groups on iodinated Ir(ppy)3 and Ir(ppym)3 was achieved via Suzuki-Miyaura cross-coupling reaction assisted by microwave irradiation. Solutions of the acid-free Ir(III) complexes 5, 6, 7, and 8 showed a strong green emission (at around 500 nm) in dimethylsulfoxide (DMSO). Protonation of three pyridyl groups of 5 and 7 causes a significant red-shift in the emission wavelength (at around 600 nm) with a decrease in emission intensity. The pH-dependent emission change of these complexes is also discussed. The generation of singlet oxygen ((1)O2) by the photoirradiation of the Ir complexes 5 and 6 was evidenced by the decomposition of 1,3-diphenylisobenzofuran (DPBF), the oxidation of thioanisole, and the oxidation of 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide (TPC). The induction of necrosis-like cell death of HeLa-S3 cells upon photoirradiation of 5 at 465 nm is also reported.

New constraint on the existence of the μ+ → e+ γ decay

The analysis of a combined data set, totaling 3.6 × 10(14) stopped muons on target, in the search for the lepton flavor violating decay μ(+) → e(+)γ is presented. The data collected by the MEG experiment at the Paul Scherrer Institut show no excess of events compared to background expectations and yield a new upper limit on the branching ratio of this decay of 5.7 × 10(-13) (90% confidence level). This represents a four times more stringent limit than the previous world best limit set by MEG.

Design and synthesis of a luminescent cyclometalated iridium(III) complex having N,N-diethylamino group that stains acidic intracellular organelles and induces cell death by photoirradiation

Cyclometalated iridium(III) complexes have received considerable attention and are important candidates for use as luminescent probes for cellular imaging because of their potential photophysical properties. We previously reported that fac-Ir(atpy)(3)4 (atpy = 2-(5'-amino-4'-tolyl)pyridine) containing three amino groups at the 5'-position of the atpy ligand shows a maximum red emission (at around 600 nm) under neutral and basic conditions and a green emission (at 531 nm) at acidic pH (pH 3-4). In this Article, we report on the design and synthesis of a new pH-sensitive cyclometalated Ir(III) complex containing a 2-(5'-N,N-diethylamino-4'-tolyl)pyridine (deatpy) ligand, fac-Ir(deatpy)(3)5. The complex exhibits a considerable change in emission intensity between neutral and slightly acidic pH (pH 6.5-7.4). Luminescence microscopic studies using HeLa-S3 cells indicate that 5 can be used to selectively stain lysosome, an acidic organelle in cells. Moreover, complex 5 is capable of generating singlet oxygen in a pH-dependent manner and inducing the death of HeLa-S3 cells upon photoirradiation at 377 or 470 nm.

P1-02-10: Vimentin Expression; as a Prognostic Factor and a Possible Molecular Target of Triple Negative Breast Cancer

BACKGROUND: Triple negative breast cancer (TNBC), characterized by absence of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), is typically associated with aggressive tumor phenotype and poor prognosis. TNBC is also considered highly heterogeneous disease. Since TNBC lacks efficient therapeutic target, it is generally treated with nonspecific cytotoxic agents. A better understanding of molecular and histopathological features of TNBC is of great importance, in order to develop a new therapeutic strategy and to improve the prognosis of TNBC. TNBC has many similarities with basal-like breast cancer (BLBC), and is also associated with stemness and BRCAness. In addition, recent studies suggest links between TNBC and epithelial-mesenchymal transition (EMT). To identify prognostic biomarkers and novel therapeutic targets, we investigated the expression of the factors associated with EMT in TNBC.

MATERIALS and METHODS: Sporadic invasive breast cancer specimens were obtained from 659 Japanese patients who underwent surgery in our department between 1994 and 2010, and 90(14%) cases were diagnosed as TNBC. The E-cadherin and vimentin mRNA expression was evaluated by quantitative RT-PCR. The E-cadherin, vimentin, CK5/6 and epidermal growth factor receptor(EGFR) protein expression was assessed by immunohistochemistry. In this study, we defined TNBC with positive expression of CK5/6 and/or EGFR as BLBC, and TNBC with low expression of E-cadherin and positive expression of vimentin as EMT-type.

RESULTS: Compared with non-TNBC cases, E-cadherin mRNA expression was significantly lower in TNBC cases (p=0.0012). Immunohistochemically, E-cadherin expression was significantly lower (p=0.0001) and vimentin expression was significantly higher (p=0.0049) in TNBC cases. Vimentin expression was associated with younger age (&lt;50 years old, p=0.021), high nuclear grade (p=0.017) and high Ki67 expression (p&lt;.001) in TNBC. Among the patients with TNBC, vimentin expression was significantly associated with poor prognosis, in terms of disease free survival (p=0.0059) and overall survival (p=0.013). Multivariate analysis showed that vimentin expression was an independent prognostic factor for both disease free survival (p=0.017) and overall survival (p=0.012). Among TNBC cases, 52(63%) cases were BLBCs and 15(18%) cases were EMT-type. Among BLBC patients, vimentin expression was also associated with significantly shorter disease free survival (p=0.0085) and overall survival (p=0.0057). The patients with both BLBC and EMT-type features showed especially poor prognosis(P=0.05). CONCLUSION: These findings suggest that elevated expression of vimentin attributes to the aggressive phenotype in TNBC patients. Vimentin expression might be useful as a molecular marker for prognosis of TNBC, and vimentin may represent a novel therapeutic target of TNBC.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-02-10.

New limit on the lepton-flavor-violating decay μ+→e+γ

We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay μ(+)e(+)γ. The likelihood analysis of the combined data sample, which corresponds to a total of 1.8×10(14) muon decays, gives a 90% C.L. upper limit of 2.4×10(-12) on the branching ratio of the μ(+)→e(+)γ decay, constituting the most stringent limit on the existence of this decay to date.