Real-time Visualization of Transcribed mRNA via Click Chemistry in a Liposomal Space

We present a CuAAC (Copper-Catalyzed Azide-Alkyne Cycloaddition) reaction protocol designed for the visualization of mRNA. To achieve this, we synthesized stable mRNA molecules incorporating the modified nucleoside analog, EU, a crucial element for fluorophore attachment. Leveraging this modified mRNA, we successfully executed the CuAAC reaction, wherein the pro-fluorophore, coumarin, was conjugated to EU on the mRNA through our meticulously designed CuAAC process. This innovative approach resulted in the emission of fluorescence, enabling both precise quantification and visual observation of mRNA. Furthermore, we demonstrated the feasibility of concurrent mRNA synthesis and visualization by seamlessly integrating the CuAAC reaction mix into the mRNA transcription process. Additionally, our novel methodology opens avenues for prospective real-time monitoring of mRNA transcription within artificial cells. These advancements hold significant promise for expanding our comprehension of fundamental cellular processes and finding applications across diverse biological contexts in the future.

Impact of protein-chromophore interaction on the retinal excited state and photocycle of Gloeobacter rhodopsin: role of conserved tryptophan residues

The function of microbial as well as mammalian retinal proteins (aka rhodopsins) is associated with a photocycle initiated by light excitation of the retinal chromophore of the protein, covalently bound through a protonated Schiff base linkage. Although electrostatics controls chemical reactions of many organic molecules, attempt to understand its role in controlling excited state reactivity of rhodopsins and, thereby, their photocycle is scarce. Here, we investigate the effect of highly conserved tryptophan residues, between which the all-trans retinal chromophore of the protein is sandwiched in microbial rhodopsins, on the charge distribution along the retinal excited state, quantum yield and nature of the light-induced photocycle and absorption properties of Gloeobacter rhodopsin (GR). Replacement of these tryptophan residues by non-aromatic leucine (W222L and W122L) or phenylalanine (W222F) does not significantly affect the absorption maximum of the protein, while all the mutants showed higher sensitivity to photobleaching, compared to wild-type GR. Flash photolysis studies revealed lower quantum yield of trans-cis photoisomerization in W222L as well as W222F mutants relative to wild-type. The photocycle kinetics are also controlled by these tryptophan residues, resulting in altered accumulation and lifetime of the intermediates in the W222L and W222F mutants. We propose that protein-retinal interactions facilitated by conserved tryptophan residues are crucial for achieving high quantum yield of the light-induced retinal isomerization, and affect the thermal retinal re-isomerization to the resting state.

AT-specific DNA visualization revisits the directionality of bacteriophage λ DNA ejection

In this study, we specifically visualized DNA molecules at their AT base pairs after in vitro phage ejection. Our AT-specific visualization revealed that either end of the DNA molecule could be ejected first with a nearly 50% probability. This observation challenges the generally accepted theory of Last In First Out (LIFO), which states that the end of the phage λ DNA that enters the capsid last during phage packaging is the first to be ejected, and that both ends of the DNA are unable to move within the extremely condensed phage capsid. To support our observations, we conducted computer simulations that revealed that both ends of the DNA molecule are randomized, resulting in the observed near 50% probability. Additionally, we found that the length of the ejected DNA by LIFO was consistently longer than that by First In First Out (FIFO) during in vitro phage ejection. Our simulations attributed this difference in length to the stiffness difference of the remaining DNA within the phage capsid. In conclusion, this study demonstrates that a DNA molecule within an extremely dense phage capsid exhibits a degree of mobility, allowing it to switch ends during ejection.

Retinal-Carotenoid Interactions in a Sodium-Ion-Pumping Rhodopsin: Implications on Oligomerization and Thermal Stability

Microbial rhodopsin (also called retinal protein)-carotenoid conjugates represent a unique class of light-harvesting (LH) complexes, but their specific interactions and LH properties are not completely elucidated as only few rhodopsins are known to bind carotenoids. Here, we report a natural sodium-ion (Na⁺)-pumping Nonlabens (Donghaeana) dokdonensis rhodopsin (DDR2) binding with a carotenoid salinixanthin (Sal) to form a thermally stable rhodopsin-carotenoid complex. Different spectroscopic studies were employed to monitor the retinal-carotenoid interaction as well as the thermal stability of the protein, while size-exclusion chromatography (SEC) and homology modeling are performed to understand the protein oligomerization process. In analogy with that of another Na⁺-pumping protein Krokinobacter eikastus rhodopsin 2 (KR2), we propose that DDR2 (studied concentration range: 2 × 10^-6 to 4 × 10^-5 M) remains mainly as a pentamer at room temperature and neutral pH, while heating above 55 °C partially converted it into a thermally less stable oligomeric form of the protein. This process is affected by both the pH and concentration. At high concentrations (4 × 10^-5 to 2 × 10^-4 M), the protein adopts a pentamer form reflected in the excitonic circular dichroism (CD) spectrum. In the presence of Sal, the thermal stability of DDR2 is increased significantly, and the pigment is stable even at 85 °C. The results presented could have implications in designing stable rhodopsin-carotenoid antenna complexes.

Surgery-related anxiety on geriatric patients undergoing total knee arthroplasty: a retrospective observational study

BACKGROUND

The prevalence of anxiety in patients undergoing total knee arthroplasty (TKA) and its association with postoperative functions are well known; however, the levels of anxiety or anxiety-related characteristics are unknown. This study aimed to investigate the prevalence of clinically significant state anxiety in geriatric patients undergoing TKA for osteoarthritis (OA) of the knee and to evaluate the anxiety-related characteristics experienced by these patients pre- and post-operatively.

METHODS

This retrospective observational study recruited patients who had undergone TKA for knee OA using general anesthesia between February 2020 and August 2021. The study participants were geriatric patients older than 65 years who had moderate or severe OA. We evaluated patient characteristics including age, sex, body mass index, smoking status, hypertension, diabetes, and cancer. We assessed their levels of anxiety status using the STAI-X which comprises 20-item scales. Clinically meaningful state anxiety was defined as a total score of 52 or higher. An independent Student's t-test was used to determine differences of STAI score between subgroups in terms of patient characteristics. And patients were asked to complete questionnaires, which assessed four areas: (1) the main cause of anxiety; (2) the most helpful factor in overcoming anxiety before surgery; (3) the most helpful factor in reducing anxiety after surgery; and (4) the most anxious moment during the entire process.

RESULTS

The mean STAI score of patients who underwent TKA was 43.0 points and 16.4% of patients experienced clinically significant state anxiety. The current smoking status affect STAI score and the proportion of patients with clinically meaningful state anxiety. The most common cause of preoperative anxiety was the surgery itself. Overall, 38% of patients reported that they experienced the greatest level of anxiety when the surgeon had recommended TKA in the outpatient clinic. The trust in the medical staff before surgery and the surgeon's explanations after surgery helped the most in reducing anxiety.

CONCLUSIONS

One in six patients before TKA experience clinically meaningful state anxiety, and about 40% of patients experience anxiety from the time they are recommended for surgery. Patients tended to overcome anxiety before TKA through trust in the medical staff, and the surgeon's explanations after surgery was found to be helpful in reducing anxiety.

Heliorhodopsin Helps Photolyase to Enhance the DNA Repair Capacity

Light quality is a significant factor for living organisms that have photosensory systems, such as rhodopsin, a seven alpha-helical transmembrane protein with the retinal chromophore. Here, we report, for the first time, the function of new rhodopsin, which is an inverted 7-transmembrane protein, isolated from Trichococcus flocculiformis. T. flocculiformis heliorhodopsin (TfHeR) works as a regulatory helper rhodopsin that binds with class 2 cyclobutane pyrimidine dimer (CPDII) photolyase to broaden the spectrum and upregulate DNA repair activity. We have confirmed their interaction through isothermal titration calorimetry (dissociation constant of 21.7 μM) and identified the charged residues for the interaction. Based on in vivo and in vitro experiments, we showed that the binding of heliorhodopsin with photolyase improved photolyase activity by about 3-fold to repair UV-caused DNA damage. Also, the DNA repair activity of TfHeR/T. flocculiformis photolyase (TfPHR) was observed in the presence of green light. Our results suggested that heliorhodopsin directly controls the activity of photolyase and coevolves to broaden the activity spectrum by protein-protein interaction. IMPORTANCE This study reports a function for Heliorhodopsin working as a regulatory helper rhodopsin that with CPDII photolyase to broaden the spectrum and upregulating the DNA repair activity. Our results suggested that heliorhodopsin directly controls photolyase activity and coevolves to broaden the DNA repair capacity by protein-protein interaction.

Heliorhodopsin binds and regulates glutamine synthetase activity

Photoreceptors are light-sensitive proteins found in various organisms that respond to light and relay signals into the cells. Heliorhodopsin, a retinal-binding membrane protein, has been recently discovered, however its function remains unknown. Herein, we investigated the relationship between Actinobacteria bacterium IMCC26103 heliorhodopsin (AbHeR) and an adjacent glutamine synthetase (AbGS) in the same operon. We demonstrate that AbHeR binds to AbGS and regulates AbGS activity. More specifically, the dissociation constant (K_d) value of the binding between AbHeR and AbGS is 6.06 μM. Moreover, the absence of positively charged residues within the intracellular loop of AbHeR impacted K_d value as they serve as critical binding sites for AbGS. We also confirm that AbHeR up-regulates the biosynthetic enzyme activity of AbGS both in vitro and in vivo in the presence of light. GS is a key enzyme involved in nitrogen assimilation that catalyzes the conversion of glutamate and ammonia to glutamine. Hence, the interaction between AbHeR and AbGS may be critical for nitrogen assimilation in Actinobacteria bacterium IMCC26103 as it survives in low-nutrient environments. Overall, the findings of our study describe, for the first time, to the best of our knowledge, a novel function of heliorhodopsin as a regulatory rhodopsin with the capacity to bind and regulate enzyme activity required for nitrogen assimilation.

A study of heliorhodopsin, an actinobacterial photoreceptor of unknown function, reveals that it interacts with glutamine synthetase, an enzyme involved in nitrogen assimilation, and regulates its activity in the presence of light, highlighting the diverse functions of rhodopsins in different organisms.

Fabrication of a Tailored, Hybrid Extracellular Matrix Composite

The extracellular matrix (ECM) is a network of connective fibers that supports cells living in their surroundings. Native ECM, generated by the secretory products of each tissue's resident cells, has a unique architecture with different protein composition depending on the tissue. Therefore, it is very difficult to artificially design in vivo architecture in tissue engineering. In this study, we fabricated a hybrid ECM scaffold from the basic structure of fibroblast-derived cellular ECMs by adding major ECM components of fibronectin (FN) and collagen (COL I) externally. It was confirmed that while maintaining the basic structure of the native ECM, major protein components can be regulated. Then, decellularization was performed to prepare hybrid ECM scaffolds with various protein compositions and we demonstrated that a liver-mimicking fibronectin (FN)-rich hybrid ECM promoted successful settling of H4IIE rat hepatoma cells. We believe that our method holds promise for the fabrication of scaffolds that provide a tailored cellular microenvironment for specific organs and serve as novel pathways for the replacement or regeneration of specific organ tissues. This article is protected by copyright. All rights reserved.

Does spiked tibial cement spacer reduce spacer-related problems in two-stage revision total knee arthroplasty for infection?

Purpose

Articulating cement spacers are frequently used in staged approaches for infected total knee arthroplasty (TKA). This study investigated whether a tibial cement spacer (TCS) with spikes could reduce spacer-related problems in two-stage revision TKA (R-TKA).

Methods

A total of 27 patients (27 knees; 10 men and 17 women) who underwent two-stage R-TKA for infected TKA were retrospectively analyzed. Group A comprised 12 patients who used TCS with spikes added to the bottom surface, whereas group B consisted of 15 patients who used conventional TCS with a flat bottom. For each group, plain radiographs were obtained after cement spacer implantation and before R-TKA to measure mediolateral (ML) translation and TCS’s tilting angle. Patients’ demographic data, ML translation of the TCS, and changes in the TCS’s tilting angle between the groups were analyzed.

Results

The mean ML translation was significantly lower in group A than that in group B (1.7 mm vs. 5.4 mm, p = 0.04). The mean change in the tilting angle was significantly lower in group A than that in group B (4.5° vs. 19.4°, p = 0.047).

Conclusion

The spiked TCS in two-stage R-TKA provides superior stability compared to the TCS with a conventional design.

Mutational analyses identify a single amino acid critical for color tuning in proteorhodopsins

Microbial rhodopsins are light-activated proteins that contain seven transmembrane alpha-helices. Spectral tuning in microbial rhodopsins is a useful optogenetic tool. In this study, we report a new site that controls spectral tuning. In the proteorhodopsins ISR34 and ISR36, a single amino-acid substitution at Cys189 caused an absorption maximum shift of 44 nm, indicating spectral tuning at a specific site. Comparison of single amino acid substitutions was conducted using photochemical and photobiological approaches. The maximum absorption for red-shift was measured for mutations at positions 189 and 105 in ISR34, both residues being equally important. Structural changes resulting from amino acid substitutions are related to pK_a  values, pumping activity, and spectral tuning.

State-Anxiety in Geriatric Patients Undergoing Surgical Treatment for Femoral Neck or Intertrochanteric Fractures

Introduction

Geriatric patients with hip fractures often experience unexpected falls and they may have unfamiliar and unpleasant experiences within a brief period. This study aimed to investigate the prevalence and levels of preoperative anxiety in patients undergoing surgical treatment for hip fractures, and to determine the anxiety-related characteristics experienced by patients during the period before and after surgery.

Materials and methods

We recruited a total of 75 geriatric patients who underwent surgical treatment for hip fractures and returned complete questionnaires. We used the State-Trait Anxiety Inventory (STAI)-X type to measure state-anxiety and defined a total score of 52 or higher as clinically meaningful state-anxiety. And, we investigated main cause of anxiety, moment of the highest level of anxiety, and the most helpful factor in overcoming anxiety before surgery and in reducing anxiety after surgery.

Results

The mean STAI score was 47.2 points and one-third of the patients experienced various levels of clinically meaningful state-anxiety. The most common cause of preoperative anxiety was the surgery itself and patients experienced the greatest level of anxiety from the night preceding the surgery to the day of the surgery. Further, patients’ trust in the medical staff prior to surgery and the surgeon’s explanation after the surgery were the most key factors in overcoming anxiety.

Conclusion

This study investigates the state-anxiety of geriatric patients undergoing surgery for hip fractures and presents important findings which can help in developing evidence-based interventions to improve the experience of patients undergoing hip surgeries.

A Bibliometric Analysis of the Field of Computer-Assisted Orthopedic Surgery during 2002–2021

Background

This study aimed to investigate the characteristics of research articles and research trends in computer-assisted orthopedic surgery (CAOS) by conducting bibliometric analyses.

Methods

CAOS-related research articles published in international journals from 2002 to 2021 were collected using the PubMed database and analyzed using the bibliometric method. Their publication year, journal name, corresponding author's country name, and the number of citations of all collected articles were noted. Contents of the articles were analyzed to evaluate the time point and anatomical site at which the digital technique was applied. Further, the 20-year period was divided into two halves of 10 years each to analyze the research trends.

Results

A total of 639 CAOS-related articles were identified. An average of 32.0 CAOS-related articles were published annually, with an average of 20.6 and 43.3 published in the first half and second half, respectively. Of all articles, 47.6% were published in the top 10 journals, and 81.2% were written in the top 10 countries. The total numbers of citations were 11.7 and 6.3 in the first and second halves, respectively, but the average annual number of citations was higher in the second half than in the first one. Articles on application of digital techniques during surgery were 62.3% and those on pre-surgery application were 36.9%. Further, articles in the knee (39.0%), spine (28.5%), and hip and pelvis (21.5%) fields accounted for 89.0% of the total publications. But the increase in publications in the said period was highest in the fields of the hand and wrist (+1,300.0%), ankle (+466.7%), and shoulder (+366.7%).

Conclusions

Over the last 20 years, the publication of CAOS-related research articles in international journals has grown steadily. Although the knee, spine, hip, and pelvis fields account for most CAOS-related research, research in new fields is also increasing. This study analyzed the types of articles and trends in CAOS-related research and provided useful information for future research in the field of CAOS.

Discovery of a new light-driven Li+/Na+-pumping rhodopsin with DTG motif

Microbial pumping rhodopsin is a seven-transmembrane retinal binding protein, which is light-driven ion pump with a functional key motif. Ion-pumping with the key motif and charged amino acids in the rhodopsin is biochemically important. The rhodopsins with DTG motif have been discovered in various eubacteria, and they function as H⁺ pump. Especially, the DTG motif rhodopsins transported H⁺ despite the replacement of a proton donor by Gly. We investigated Methylobacterium populi rhodopsin (MpR) in one of the DTG motif rhodopsin clades. To determine which ions the MpR transport, we tested with various monovalent ion solutions and determined that MpR transports Li⁺/Na⁺. By replacing the three negatively charged residues residues which are located in helix B, Glu32, Glu33, and Asp35, we concluded that the residues play a critical role in the transport of Li⁺/Na⁺. The MpR E33Q transported H⁺ in place of Li⁺/Na⁺, suggesting that Glu33 is a Li⁺/Na⁺ binding site on the cytoplasmic side. Gly93 in MpR was replaced by Asp to convert from the Li⁺/Na⁺ pump to the H⁺ pump, resulting in MpR G93D transporting H⁺. Dissociation constant (K_d) values of Na⁺ for MpR WT and E33Q were determined to be 4.0 and 72.5 mM, respectively. These results indicated the mechanism by which MpR E33Q transports H⁺. Up to now, various ion-pumping rhodopsins have been discovered, and Li⁺/Na⁺-pumping rhodopsins were only found in the NDQ motif in NaR. Here, we report a new light-driven Na⁺ pump MpR and have determined the important residues required for Li⁺/Na⁺-pumping different from previously known NaR.

Assembly of Natively Synthesized Dual Chromophores Into Functional Actinorhodopsin

Microbial rhodopsin is a simple solar energy-capturing molecule compared to the complex photosynthesis apparatus. Light-driven proton pumping across the cell membrane is a crucial mechanism underlying microbial energy production. Actinobacteria is one of the highly abundant bacterial phyla in freshwater habitats, and members of this lineage are considered to boost heterotrophic growth via phototrophy, as indicated by the presence of actino-opsin (ActR) genes in their genome. However, it is difficult to validate their function under laboratory settings because Actinobacteria are not consistently cultivable. Based on the published genome sequence of Candidatus aquiluna sp. strain IMCC13023, actinorhodopsin from the strain (ActR-13023) was isolated and characterized in this study. Notably, ActR-13023 assembled with natively synthesized carotenoid/retinal (used as a dual chromophore) and functioned as a light-driven outward proton pump. The ActR-13023 gene and putative genes involved in the chromophore (retinal/carotenoid) biosynthetic pathway were detected in the genome, indicating the functional expression ActR-13023 under natural conditions for the utilization of solar energy for proton translocation. Heterologous expressed ActR-13023 exhibited maximum absorption at 565 nm with practical proton pumping ability. Purified ActR-13023 could be reconstituted with actinobacterial carotenoids for additional light-harvesting. The existence of actinorhodopsin and its chromophore synthesis machinery in Actinobacteria indicates the inherent photo-energy conversion function of this microorganism. The assembly of ActR-13023 to its synthesized chromophores validated the microbial community's importance in the energy cycle.

Promoting crystallization of intrinsic membrane proteins with conjugated micelles

A new technique for promoting nucleation and growth of membrane protein (MP) crystals from micellar environments is reported. It relies on the conjugation of micelles that sequester MPs in protein detergent complexes (PDCs). Conjugation via amphiphilic [metal:chelator] complexes presumably takes place at the micelle/water interface, thereby bringing the PDCs into proximity, promoting crystal nucleation and growth. We have successfully applied this approach to two light-driven proton pumps: bacteriorhodopsin (bR) and the recently discovered King Sejong 1-2 (KS1-2), using the amphiphilic 4,4'-dinonyl-2,2'-dipyridyl (Dinonyl) (0.7 mM) chelator in combination with Zn2+, Fe2+, or Ni2+ (0.1 mM). Crystal growth in the presence of the [metal-chelator] complexes leads to purple, hexagonal crystals (50-75 µm in size) of bR or pink, rectangular/square crystals (5-15 µm) of KS1-2. The effects of divalent cation identity and concentration, chelator structure and concentration, ionic strength and pH on crystal size, morphology and process kinetics, are described.

Trends in knee surgery research in the official journal of the Korean Knee Society during the period 1999-2018: a bibliometric review

BACKGROUND

We applied bibliometric tools to original articles published in the official journal of the Korean Knee Society between 1999 and 2018 to identify their characteristics related to knee surgery and to examine the changes in research trends in the last 20 years.

METHODS

Over a 20-year period, 579 original articles were published in the journal Knee Surgery and Related Research (KSRR). We analyzed the title, keywords, and abstract of the article to analyze the research topics and assigned original articles to seven surgical categories as follows: total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), high tibial osteotomy (HTO), arthroscopy, surgery for cruciate ligament, revision surgery, and other surgery. To analyze the trends in research, we divided the study period into two equal parts of 10 years each, examined the percentage of articles in each decade, and analyzed topic trends using the growth rate.

RESULTS

Among the original articles, 86 on the topic of non-surgery were excluded, and 493 original articles related surgical research were included. Articles related to surgery accounted for 85.2% of the total original articles published annually. By period, this was 85.6% in the first half and 84.8% in the late half (p = 0.76). A total of 493 original articles related to surgery, with the largest number of TKA-related research at 52.1%. In the study period, the largest increase in the percentage of articles was on the topic of HTO surgery, by 149%. The topics of UKA and revision surgery increased by 95.3% and 33.9%. The topic of TKA increased by 5.9% and the topic of surgery for cruciate ligament decreased by 18.7%. The topic of arthroscopy showed the largest decrease, by 47.6%.

CONCLUSIONS

The bibliometric findings of this study suggest that the majority of surgery-related original articles published in KSRR during the last 20 years involved research about TKA surgery, and the greatest relative increase over the study period involved research about HTO surgery. The authors expect that the analysis of characteristics and research trends of original articles published in KSRR will provide useful information about KSRR for future researchers.

Incidence, survival, and risk of cardiovascular events in adult inflammatory myopathies in South Korea: a nationwide population-based study

OBJECTIVE

Epidemiological studies on inflammatory myopathies (IMs) show widely variable results, and studies on Asians are lacking. Despite emerging interest in the cardiovascular disease (CVD) risk associated with IMs, the prevalence of CVD in IM patients and its impact on mortality remain unclear. We conducted a nationwide, population-based study on the incidence, mortality, and associated major CVD events of IMs in the Republic of Korea over 11 years.

METHOD

Using the nationwide, population-based National Health Insurance claims database and the Rare Intractable Disease registration programme, we estimated incidence, mortality, and CVD occurrence. Survival was examined using the Kaplan-Meier method. Mortality rate in IMs with CVD was analysed by Cox proportional hazards regression.

RESULTS

There were 3014 incident cases, 640 of whom died during the study period. The mean annual incidence was 7.16/10⁶. Dermatomyositis (DM) and polymyositis (PM) had 5 year survival rates of 76.8% and 79.3%, respectively. Cardiovascular events occurred in 155 patients and 40.6% of IM patients with CVD died. Acute myocardial infarction in men had the highest risk of any CVD event in both DM [standardized incidence ratio (SIR) 4.2, 95% confidence interval (95% CI) 2.4-7.2] and PM (SIR 3.5, 95% CI 1.8-7.0). Haemorrhagic stroke had the highest hazard ratio (HR) in both DM (HR 2.31, 95% CI 1.13-4.70) and PM patients (HR 2.10, 95% CI 1.03-4.27) compared with the general population with CVD.

CONCLUSION

We found persistently low incidence, poor survival, and high major CVD incidence in IMs, and increased mortality in IMs with CVD.

Photochemical characterization of flavobacterial rhodopsin: The importance of the helix E region for heat stability

Although many microbial rhodopsins have been discovered many of organisms in a variety of habitats, little is known about the property and diversity of rhodopsin in flavobacteria. Recent studies discovered that many proteorhodopsin (PR)-like proteins exist in genomes of flavobacteria. Following the isolation of a flavobacterial rhodopsins (FR) from the flavobacteria IMCC1997 from the East Sea of Korea, we characterized its photochemical features. We confirmed that the FR expression is induced by light in the IMCC1997 cell. Upon receiving light energy in vitro, the proton acceptor (D83) and donor (E94) of the FR translocate protons from intracellular to extracellular regions. Compared with proteorhodopsin (PR), the FR from IMCC 1997 cells is very unstable, which may be explained by their primary sequence differences. The ratio of all trans/13-cis retinal conformation does not influence this stability. To measure the stability of FR, we tested heat endurance at 70 °C and found that the heat endurance time of some FR mutants increased. Based upon these results, we found the helix E of this protein to be critical for the unstability of FR.

Multi-Factor Regulation of the Master Modulator LeuO for the Cyclic-(Phe-Pro) Signaling Pathway in Vibrio vulnificus

LeuO plays the role of a master regulator in the cyclic-L-phenylalanine-L-proline (cFP)-dependent signaling pathway in Vibrio vulnificus. cFP, as shown through isothermal titration calorimetry analysis, binds specifically to the periplasmic domain of ToxR. Binding of cFP triggers a change in the cytoplasmic domain of ToxR, which then activates transcription of leuO encoding a LysR-type regulator. LeuO binds to the region upstream of its own coding sequence, inhibiting its own transcription and maintaining a controlled level of expression. A five-bp deletion in this region abolished expression of LeuO, but a ten-bp deletion did not, suggesting that a DNA bending mechanism is involved in the regulation. Furthermore, binding of RNA polymerase was significantly lower both in the deletion of the ToxR binding site and in the five-bp deletion, but not in the ten-bp deletion, as shown in pull-down assays using an antibody against RNA polymerase subunit α. In summary, multiple factors are involved in control of the expression of LeuO, a master regulator that orchestrates downstream regulators to modulate factors required for survival and pathogenicity of the pathogen.

Functional importance of the oligomer formation of the cyanobacterial H+ pump Gloeobacter rhodopsin

Many microbial rhodopsins self-oligomerize, but the functional consequences of oligomerization have not been well clarified. We examined the effects of oligomerization of a H⁺ pump, Gloeobacter rhodopsin (GR), by using nanodisc containing trimeric and monomeric GR. The monomerization did not appear to affect the unphotolyzed GR. However, we found a significant impact on the photoreaction: The monomeric GR showed faint M intermediate formation and negligible H⁺ transfer reactions. These changes reflected the elevated pKa of the Asp121 residue, whose deprotonation is a prerequisite for the functional photoreaction. Here, we focused on His87, which is a neighboring residue of Asp121 and conserved among eubacterial H⁺ pumps but replaced by Met in an archaeal H⁺ pump. We found that the H87M mutation removes the “monomerization effects”: Even in the monomeric state, H87M contained the deprotonated Asp121 and showed both M formation and distinct H⁺ transfer reactions. Thus, for wild-type GR, monomerization probably strengthens the Asp121-His87 interaction and thereby elevates the pKa of Asp121 residue. This strong interaction might occur due to the loosened protein structure and/or the disruption of the interprotomer interaction of His87. Thus, the trimeric assembly of GR enables light-induced H⁺ transfer reactions through adjusting the positions of key residues.

Protein conformational alterations induced by the retinal excited state in proton and sodium pumping rhodopsins

Retinal proteins' biological activity is triggered by the retinal chromophore's light absorption, which initiates a photocycle. However, the mechanism by which retinal light excitation induces the protein's response is not completely understood. Recently, two new retinal proteins were discovered, namely, King Sejong 1-2 (KS1-2) and Nonlabens (Donghaeana) dokdonensis (DDR2), which exhibit H+ and Na+ pumping activities, respectively. To pinpoint whether protein conformation alterations can be achieved without light-induced retinal C13[double bond, length as m-dash]C14 double-bond isomerization, we utilized the hydroxylamine reaction, which cleaves the protonated Schiff base bond through which the retinal chromophore is covalently bound to the protein. The reaction is accelerated by light even though the cleavage is not a photochemical reaction. Therefore, the cleavage reaction may serve as a tool to detect protein conformation alterations. We discovered that in both KS1-2 and DDR2, the hydroxylamine reaction is light accelerated, even in artificial pigments derived from synthetic retinal in which the crucial C13[double bond, length as m-dash]C14 double-bond isomerization is prevented. Therefore, we propose that in both proteins the light-induced retinal charge redistribution taking place in the retinal excited state polarizes the protein, which, in turn, triggers protein conformation alterations. A further general possible application of the present finding is associated with other photoreceptor proteins having retinal or other non-retinal chromophores whose light excitation may affect the protein conformation.

Abstract P2-02-11: Combinational treatment of biguanides and fatty acid β-oxidation inhibitor in triple-negative breast cancers

Among breast cancers (BCs), the driver pathways and therapeutic targets are still poorly understood for triple negative (TN) BCs. Advances in cancer metabolism research over the last decade have enhanced our understanding on metabolic reprogramming in cancer therapy. We have previously shown that metabolic reprogramming to fatty acid β-oxidation (FAO) is a major energy pathway in metastatic TNBC. Moreover, we reported that FAO regulates c-Src, one of the frequently upregulated oncopathways in TNBC via autophosphorylation of Src at Y419. Since FAO inhibitors alone cannot effectively control the tumor progression in TNBC, suitable combination therapies with other metabolic targets are necessary. Recently increasing evidences show that anti-diabetic biguanides have attractive anticancer effect in various cancer types including BC. However, its significance as an anticancer drug is not well established due to parallel metabolic pathways that support tumor growth.

Phenformin, a biguanide derivative similar to metformin, has a greater potency than metformin. Like metformin, phenformin also inhibits mitochondrial electron transport chain (ETC) through complex I inhibition. In addition, biguanides lead to the activation of AMPK, which plays a key role in insulin signaling and energy sensing. Importantly, AMPK is an upstream regulator of FAO pathway because it can phosphorylate ACC to activate FAO. Considering the dependency of TNBC to FAO, we evaluated the therapeutic significance of the combination of biguanides(ETC inhibitors) and FAO inhibitors in TNBC progression and metastasis. We hypothesize that blocking both 'arms' of the pathway can provide more pronounced and durable responses in TNBCs. Our different in vitro and in vivo studies using TNBC cell line and PDX models suggest that the combination of both inhibitors can provide better therapeutic significance in metastatic TNBCs. This is a rationale and cost-effective metabolic approach to manage the currently non-targetable metastatic TNBCs. Further investigation into the clinical effectiveness of this combination may provide better treatment opportunities for TNBC patients.

Citation Format: Park JH, Jung KH, Vithayathil S, Jia D, Kaipparettu BA. Combinational treatment of biguanides and fatty acid β-oxidation inhibitor in triple-negative breast cancers [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 P2-02-11.

Abstract P6-17-23: Randomized phase II study of lapatinib plus vinorelbine versus vinorelbine in patients with HER2 positive metastatic breast cancer progressed after lapatinib and trastuzumab treatment

Background

The continuum of anti-HER2 agents is regarded as a standard strategy for HER2 positive metastatic breast cancer patients who had progressed disease with anti-HER2 agent- containing treatments. However, there has been lack of data on which agents should be continued and how long continuous anti-HER2 therapies would be effective. This study was aimed to evaluate the efficacy of lapatinib plus vinorelbine in HER2 positive metastatic breast cancer patients who had progressed on both trastuzumab and lapatinib treatments.

Methods

A total of 149 patients were randomly assigned to lapatinib with vinorelbine (LV) (n=75; laptinib, 1000mg daily ; vinorelbine 20mg/m2 D1,D8 q3w) or vinorelbine alone (V) (n=74; 30mg/m2 D1,D8 q3w). The stratification factors were followings; 1) visceral metastasis, 2) previous response to lapatinib treatment, CR+PR vs. SD ≥ 12 weeks. The primary endpoint was progression free survival (PFS) rate at 18 weeks. The secondary endpoints were objective response rate (ORR), PFS, and overall survival (OS).

Results :

Both arms were well balanced in various clinical factors. The median number of previous anti-HER2 therapies were 2 (range 2-5). There was no significant difference in PFS rate at 18 weeks between LV and V arms (44.0% vs 36.5%, p=0.44). ORR was 19.7% in LV arm and 16.9% in V arm (p=0.881). PFS and OS did not differ between two arms (LV vs V; median PFS, 16weeks vs 12 weeks, HR= 0.86, 95% CI 0.61-1.22, p=0.41; median OS, 15.0 months vs 18.9 months, HR= 1.07, 95% CI 0.72-1.58, p=0.72). In subgroup analysis, there was no difference in PFS and OS between two arms according to previous response to lapatinib (median PFS, CR+PR vs. SD ≥ 12 weeks, 12.1weeks vs.17.4 weeks; HR= 1.242, 95% CI 0.881-1.751, p=0.215; median OS, 14.9 months vs. 19.4 months; HR= 1.179, 95% CI 0.797-1.744, p=0.41). Most common adverse events in both arms were neutropenia which was more often observed in V arm (55% vs 73%, p=0.03). Overall, the profiles of adverse events were similar in both arms and all were manageable.

Conclusion

Lapatinib plus vinorelbine treatment was tolerable, however, it did not demonstrate the clinical benefits compared to vinorelbine alone in HER2 positive metastatic breast cancer patients after progression on both trastuzumab and lapatinib.

Citation Format: Sim SH, Park IH, Jung KH, Kim S-B, Ahn J-H, Lee K-H, Im S-A, Im Y-H, Park YH, Sohn JH, Kim YJ, Lee S, Kim H-J, Chae YS, Park K-H, Nam B-H, Lee KS, Ro J. Randomized phase II study of lapatinib plus vinorelbine versus vinorelbine in patients with HER2 positive metastatic breast cancer progressed after lapatinib and trastuzumab treatment [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 P6-17-23.

Abstract P3-11-07: Exploratory biomarker analysis from a phase II, multicenter, randomized trial of eribulin plus gemcitabine(EG) versus paclitaxel plus gemcitabine(PG) as first-line chemotherapy for human epidermal growth factor receptor 2 (HER2)- negative metastatic breast cancer(MBC): Korean cancer study group trial (KCSG BR13-11)

Introduction : A phase II, multicenter, randomized clinical trial of the comparison between eribulin plus gemcitabine (EG) and paclitaxel plus gemcitabine (PG) as first-line chemotherapy for patients with human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) found EG was less neurotoxic, but had similar efficacy of PG. In this study, we performed exploratory biomarker analysis of the impact of genetic alterations on the efficacy according to EG and PG chemotherapy.

Methods : This biomarker study was conducted using tumor samples from 40patients. When tissue collection was possible after disease progression, we performed paired sample analysis. Tumor DNA and RNA were extracted from formalin-fixed, paraffin-embedded tissues. To perform targeted deep sequencing, we used CancerScanTM, a 375 cancer gene panel. And we performed an nCounter expression assay for gene expression analysis using 730 PanCancer panel and 730 Immune panel.

Results: In total, we obtained 44 tissue samples from 40 patients. Twenty two patients were assigned in EG arm and 18 patients were in PG arm. Thirty-eight were at baseline and six after disease progression. Gene expression assay were performed in 44 tissue samples but only 31 samples were possible to be targeted deep sequencing.

We performed differently expressed gene(DEG) analysis for detecting the association between level of gene expression and disease progression. In this analysis, high expression of CCNE1, TGFB4 and BAMBI and low expression of DDB2, CD14 and SHC3 were associated with disease progression among 730 PanCancer panel genes (p<0.05, respectively). In terms of immune panel genes, most of immune related genes were highly expressed in a group without disease progression compared with that with disease progression. Only 2 genes, C8G and CD24 were highly expressed in a group with disease progression. Paired sample analysis showed that expression levels of THBS4 and CD27 decreased after disease progression while those of CCNE2 and FGFR4 increased.

In targeted deep sequencing, FAT3 (42.3%) was most frequently mutated gene followed by PKHD1, PIK3CA and TP53. Among mutated genes, EWSR1 mutation and upstream mutation of ETV1 were associated with disease progression, respectively (p<0.05, respectively). In mutation signature analysis, signature 1 (S, age related), S3(homologous recombination deficiency, HRD), S6 (mismatch repair, MMR), S20(MMR) and S21(microsatellite instability, MSI) were enriched in this population. Mutation signature 3 related to short disease free survival (p=0.0026).

Conclusion: In gene expression analysis, high expression of TGF-B signaling pathway related genes was associated with disease progression while high expression of immune related genes were related to prolonged disease free survival. In mutation analysis, EWSR1 and ETV1 mutations indicated short disease free interval and HRD mutation signature was also related to poor prognosis.

Citation Format: Kim J-Y, Lee EJ, Park KH, Im S-A, Kim S-B, Sohn SH, Lee KS, Chae YS, Lee KH, Kim JH, Im Y-H, Kim T-Y, Lee K-H, Ahn J-H, Kim GM, Park IH, Lee SJ, Han HS, Kim SH, Jung KH, Park YH. Exploratory biomarker analysis from a phase II, multicenter, randomized trial of eribulin plus gemcitabine(EG) versus paclitaxel plus gemcitabine(PG) as first-line chemotherapy for human epidermal growth factor receptor 2 (HER2)- negative metastatic breast cancer(MBC): Korean cancer study group trial (KCSG BR13-11) [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 P3-11-07.

Abstract P4-01-11: Genomic alterations of cell-free DNA in early breast cancer patients with recurrence

Cell-free DNA (cfDNA), as a non-invasive strategy, provides substantial benefit to overcome tumor heterogeneity. Surveillance of recurrence after standard treatment in early breast cancer (BC) using cfDNA, enables to detect minimal residual disease (MRD), also to identify genomic alterations driving recurrences. We aimed to assess the role of cfDNA in detecting MRD by investigating genomic alterations of 1)primary, recurred tumor and 2)cfDNA at time of recurrence using deep targeted sequencing. Fifty-four early BC patients were enrolled prospectively between 2014 and 2017 at time of recurrence. Median disease free interval was 28.5 months (rage 6.2-49.8). 62.7% (32/51) were hormone receptor (HR) positive (28 HRpos/HER2neg, 4 HRpos/HER2pos), 11.8% (6/51) were HRneg/HER2pos and 25.5% (13/51) were triple negative BCs. 59.3% (32/54) patients developed loco-regional recurrence (15 local recurrence only, 13 regional only, 4 with both) and distant metastasis was observed among 40.7% (22/54) patients. Cell-free DNA was extracted from 5cc blood at time of recurrence. Deep targeted sequencing was performed using customized NGS panel –encompassing 426 cancer-related target coding region, 242 fusion and amplification-related region- of cfDNA and FFPE(formalin fixed paraffin embedded) tumor samples archived from surgical resection or biopsy. Deep targeted sequencing data was successfully performed in 72.1% (31/43) plasma samples and sequencing yield was significantly lower when stored for more than 2yrs (46.2% vs 83.3%).

Mutations of cfDNA and tumor (primary, recurred) were analyzed. Mean sequencing depth of cfDNA and FFPE were x425.7 and x777.6 respectively. Median number of pathogenic mutations found in primary tumor, cfDNA and recurred tumor were 27(range 12-99), 25(range 8-85) and 9(range 0-23). Among mutations found in primary tumor, 27.4% were shared mutations (range 8.1%-72.7%) with recurred tumor and 26.1% were shared mutations (range 4.7%-69.2%) observed in cfDNA sample. Among mutations found in recurred tumor, 40.9% were observed in cfDNA (range 17.7-87.5%). In primary tumor, median number of mutations with allelic fraction (MAF)>10% were 12 (range 4-21) and at least one mutation was found in cfDNA at time of recurrence. Among mutations with MAF>10%, 59.4% and 69.1% were found in cfDNA and recurred tumor. Known oncogenic mutations of PIK3CA, TP53, GATA3, AKT1, ESR1, RELN, ERBB2, ERBB3, BRCA1 mutation were found. PIK3CA gene (p.H1047R) was found in two cases both in primary tumor and cfDNA at recurrence (MAF 11.4% vs 5.3% and 12.3% vs 15.4%) suggesting de novo driver mutation. One patient developed regional recurrence during adjuvant aromatase inhibitor with ESR1 V392I mutation in both cfDNA and recurred tumor (MAF 48.1 and 54.5%), while another patient's recurred tumor during aromatase inhibitor harbored ESR1 D538G mutation exclusively in recurred tumor with MAF <1%. Both patients had no ESR1 hotpot mutation in primary tumor.

Our data showed sequencing yield of 83.3% in plasma samples within 2yr. Pathogenic mutations in primary tumor, especially when MAF>10%, half of them was observed in cfDNA at time of recurrence. ESR1 mutation should be included in cfDNA surveillance for patients undergoing endocrine therapy even absent in primary tumor.

Citation Format: Kim J, Jo WK, Kim KY, Kim BJ, Lee SB, Lee HJ, Yu JH, Kim HJ, Chung IY, Ko BS, Kim S-B, Jung KH, Ahn JH, Chang S, Lee JW, Son BH, Ahn SH. Genomic alterations of cell-free DNA in early breast cancer patients with recurrence [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 P4-01-11.

Abstract P2-02-14: Metabolic regulation and drug resistance in c-Src activated triple negative breast cancer

c-Src (Src) is a proto-oncogene involved in signaling that culminates in the control of multiple biological functions. Src is also one of the most frequently upregulated pathways in triple negative breast cancer (TNBC). Dysregulation of Src has been detected in TNBC and is strongly associated with tumor metastasis and poor prognosis. However, even after promising preclinical studies, Src inhibitors did not show major clinical advantage in unselected TNBC populations. We have previously published that metastatic TNBC has high energy-dependency to mitochondrial fatty acid beta-oxidation (FAO) and FAO activates Src by inducing autophosphorylation at Y419. However, our recent analysis suggests that as observed with the Src inhibitors, TNBC tumors treated with FAO inhibitors also develop drug-resistance and continue tumor growth. Evaluation of their drug resistance mechanism revealed that while short-term inhibition of FAO or Src induces autophagic and apoptotic cell deaths, long-term inhibition results in autophagy-mediated drug resistance and survival. Further analyses suggest that FAO and Src inhibitors activate mitogen-activated protein (MAP) kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway via the induction of cellular reactive oxygen species (ROS) in TNBC. Activated MEK/ERK then induces survival pathways for drug resistance and tumor survival. Validation of in vitro findings using in vivo TNBC models confirmed that combination of FAO/Src inhibitors with MEK/ERK inhibitors can provide significant benefit to overcome the therapeutic resistance of TNBC. These findings open-up new therapeutic opportunities to manage TNBC patients with currently non-targetable metastatic tumors.

Citation Format: Jung KH, Park JH, Sirupangi T, Jia D, Gandhi N, Pudakalakatti S, Elswood J, Porter W, Putluri N, Zhang XH-F, Chen X, Bhattacharya PK, Creighton CJ, Lewis MT, Rosen JM, Wong L-JC, Das GM, Osborne CK, Rimawi MF, Kaipparettu BA. Metabolic regulation and drug resistance in c-Src activated triple negative breast cancer [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 P2-02-14.

Biosynthetic production of fully carbon-13 labeled retinal in E. coli for structural and functional studies of rhodopsins

The isomerization of a covalently bound retinal is an integral part of both microbial and animal rhodopsin function. As such, detailed structure and conformational changes in the retinal binding pocket are of significant interest and are studied in various NMR, FTIR, and Raman spectroscopy experiments, which commonly require isotopic labeling of retinal. Unfortunately, the de novo organic synthesis of an isotopically-labeled retinal is complex and often cost-prohibitive, especially for large scale expression required for solid-state NMR. We present the novel protocol for biosynthetic production of an isotopically labeled retinal ligand concurrently with an apoprotein in E. coli as a cost-effective alternative to the de novo organic synthesis. Previously, the biosynthesis of a retinal precursor, β-carotene, has been introduced into many different organisms. We extended this system to the prototrophic E. coli expression strain BL21 in conjunction with the inducible expression of a β-dioxygenase and proteo-opsin. To demonstrate the applicability of this system, we were able to assign several new carbon resonances for proteorhodopsin-bound retinal by using fully ¹³C-labeled glucose as the sole carbon source. Furthermore, we demonstrated that this biosynthetically produced retinal can be extracted from E. coli cells by applying a hydrophobic solvent layer to the growth medium and reconstituted into an externally produced opsin of any desired labeling pattern.

Fluorescence Enhancement of a Microbial Rhodopsin via Electronic Reprogramming

The engineering of microbial rhodopsins with enhanced fluorescence is of great importance in the expanding field of optogenetics. Here we report the discovery of two mutants (W76S/Y179F and L83Q) of a sensory rhodopsin from the cyanobacterium Anabaena PCC7120 with opposite fluorescence behavior. In fact, while W76S/Y179F displays, with respect to the wild-type protein, a nearly 10-fold increase in red-light emission, the second is not emissive. Thus, the W76S/Y179F, L83Q pair offers an unprecedented opportunity for the investigation of fluorescence enhancement in microbial rhodopsins, which is pursued by combining transient absorption spectroscopy and multiconfigurational quantum chemistry. The results of such an investigation point to an isomerization-blocking electronic effect as the direct cause of instantaneous (subpicosecond) fluorescence enhancement.

Enhancement of radionuclide bio-decontamination by screening highly efficient microalgae for Sr biomineralization

In this study, a new strategy for improving the radionuclide bio-decontamination (RBD) activity of microalgae by screening a better strain with high potential for biomineral production has been proposed. A noninvasive dielectrophoresis (DEP)-based microalgae screening microplatform has been used to select the highly capable microalgae in RBD. Microalgae (Chlorella vulgaris KMMCC9) with a high degree of competence in strontium (Sr) removal were successfully segregated against Chlorella vulgaris KCTC AG10002 that has relatively weak Sr removal activity under an AC electric field. C. vulgaris KMMCC9 with higher Sr biomineral competence (HSC) was also successfully segregated against others with lower Sr biomineral competence (LSC). Furthermore, after the screening and large-scale cultivation of C. vulgaris KMMCC9 with HSC, the microalgae showed highly effective Sr bio-decontamination in both non-radioactive and radioactive Sr contaminated water compared to wild-type (WT).

The Use of a Chimeric Rhodopsin Vector for the Detection of New Proteorhodopsins Based on Color

Student microbial ecology laboratory courses are often conducted as condensed courses in which theory and wet lab work are combined in a very intensive short time period. In last decades, the study of marine microbial ecology is increasingly reliant on molecular-based methods, and as a result many of the research projects conducted in such courses require sequencing that is often not available on site and may take more time than a typical course allows. In this work, we describe a protocol combining molecular and functional methods for analyzing proteorhodopsins (PRs), with visible results in only 4–5 days that do not rely on sequencing. PRs were discovered in oceanic surface waters two decades ago, and have since been observed in different marine environments and diverse taxa, including the abundant alphaproteobacterial SAR11 group. PR subgroups are currently known to absorb green and blue light, and their distribution was previously explained by prevailing light conditions – green pigments at the surface and blue pigments in deeper waters, as blue light travels deeper in the water column. To detect PR in environmental samples, we created a chimeric plasmid suitable for direct expression of PRs using PCR amplification and functional analysis in Escherichia coli cells. Using this assay, we discovered several exceptional cases of PRs whose phenotypes differed from those predicted based on sequence only, including a previously undescribed yellow-light absorbing PRs. We applied this assay in two 10-days marine microbiology courses and found it to greatly enhance students’ laboratory experience, enabling them to gain rapid visual feedback and colorful reward for their work. Furthermore we expect this assay to promote the use of functional assays for the discovery of new rhodopsin variants.

Genome Variations of Evolved Escherichia coli ET8 With a Rhodopsin-Based Phototrophic Metabolism

We reported that the phototrophic metabolism via plasmid-originated Gloeobacter rhodopsin(GR)-expression is improved in Escherichia coli ET5 harboring pKJ606-GR by a genomic point mutation (dgcQ^C1082A ) encoding a transmembrane cell signaling protein (Microb. Cell Fact. 16:111, 2017). Another evolved descendant is isolated from the chemostat, and the genome variation of the strain named ET8 harboring pKJ606-GR is investigated in this study. Whole genome sequencing analysis identifies a single point mutation (C3831976A) located in the non-coding upstream region of kdtA and an IS4 insertional mutation at galU^G706 without any mutations in the plasmid. ET8 strain shows enhanced kdtA transcription and no growth in the D-galactose or lactose sole carbon sourced minimal media. Size of ET8 strain are almost identical to that of the ancestor. Phototrophic growth and proton pumping in ET8 expressing GR (ET8 + GR) are increased 1.5-fold and threefold, respectively, compared with those in the ancestor (W3110 + GR). To verify the effects of the genomic mutations, either the kdtA-upregulation or the galU-disruption is conducted in the ancestor. Both the kdtA-upregulation and the galU-disruption result in the drastic increases of proton-pumping. The physiological properties arising from the genomic variations of the evolved host with the new phototrophic metabolism are further discussed.

Abstract P2-09-21: Molecular alterations and poziotinib, a pan-HER inhibitor efficacy in human epidermal growth factor receptor 2(HER2) positive breast cancers: Combined exploratory biomarker analysis from phase II clinical trial of poziotinib for refractory HER2 positive breast cancer(BC) patients

Introduction: Poziotinib is a novel, pan-HER kinase inhibitor which showed potent anti-tumor activities through irreversible inhibition of HER family tyrosine kinases in preclinical and early clinical studies. Recent the open-label, multicenter phase II trial of poziotinib monotherapy evaluated that poziotinib is a new promising option for patients with HER2-positive metastatic BC who have failed more than two HER2 targeted therapy (NCT02418689). We evaluated genetic profiles of HER2-positive metastatic BC and investigated potential biomarkers of poziotinib for HER2-positive metastatic BC (MBC). Methods: All participants were diagnosed as HER2-positive BCs according to American Society of Clinical Oncology/College of American Pathologists HER2 guideline and provided tissue specimens that would be possible to extract DNA and RNA for next generation sequencing. We performed targeted deep sequencing with a customized 381 cancer gene panel (CancerSCAN™) and analyzed the relationship among the sequencing data, immunohistochemistry and clinical outcome.

Results: From Apr 2015 to Feb 2016, 106 patients were enrolled in the trial from 7 institutes in Korea. Of 106 patients, biomarker data were available for 79 patients. TP53 was the most frequently mutated gene (70.8%) followed by PIK3CA (45.6%). HER2 single nucleotide variant (SNV) was detected in 13 BCs (16.5%) and HER3 SNV was in 9 (11.4%). The score of HER2 immunohistochemistry (IHC) was 3+ in 68 BCs and 2+ with positive in situ hybridization in 11 BCs. In copy number variant (CNV) analysis, HER2 amplification (86.1%) was most frequently observed and followed by CDK12 amplification (58.2%) and APOBEC3B deletion (30.4%). IHC score of HER2 was positively correlated to copy number (CN) of HER2 (P=0.001) but 11 breast cancer tissue did not have copy number amplification of HER2 (13.9%) (Six of HER2 IHC score 2+ and 5 of 3+). The median progression free survival (PFS) was 4.04 months (95% CI, 2.96 - 4.40) for patients who treated with poziotinib in this study. PIK3CA activating mutations were associated with short PFS compared to wild type (WT) and other SNVs (Median PFS of activating mutations vs. WT and others: 2.66 vs. 4.40 (months), P=0.009). HER2 CN amplification was positively correlated to duration of PFS (Median PFS of no amplification vs. 4 ≤ CN < 16 vs. 16 ≤ CN: 2.56 vs. 3.02 vs. 4.86 (months), P=0.032). HER2 SNVs prolonged duration of PFS without statistical significance (Median PFS of HER2 SNVs vs. WT: 4.24 vs. 3.19 (months), P=0.114), but 10 of 13 BCs with HER2 SNV (76.9%) had clinical benefit from poziotinib and 5 BCs (38.5%) had durable response more than 6 months. Conclusion: In this biomarker analysis, SNV of HER2 was frequently observed in HER2 positive MBCs and HER2 CN amplification was detected not in all. High CN amplification of HER2 derived longer PFS than those with low CN. To contrary to this, activating PIK3CA mutations shorten PFS compared to those with WT. In addition, HER2 SNVs might be a potential biomarker of poziotinib in HER2-positive MBC. Further functional study would be warranted.

Citation Format: Kim J-Y, Lee E, Park K, Jung HH, Park W-Y, Lee K-H, Sohn JH, Lee KS, Jung KH, Kim J-H, Lee KH, Im S-A, Park YH. Molecular alterations and poziotinib, a pan-HER inhibitor efficacy in human epidermal growth factor receptor 2(HER2) positive breast cancers: Combined exploratory biomarker analysis from phase II clinical trial of poziotinib for refractory HER2 positive breast cancer(BC) patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-09-21.

Abstract P6-06-04: Targeting replication stress in triple negative breast cancer treatment regimen: An emerging approach

Triple-negative breast cancers (TNBCs) represent aggressive heterogeneous subtype of breast cancer with poor clinical outcome. TNBCs have been reported to have high levels of replication stress due to i) various oncogene activations (C-myc or EGFR) ii) germline BRCA mutations iii) “BRCAness” in the absence of BRCA mutations in sporadic TNBCs. Replication stress is known to cause genomic instability, promote tumorigenesis and plays a critical role in therapy resistance in TNBCs. Therefore, targeting replication stress has emerged as an effective approach for better TNBC treatment through further downregulation of the remaining checkpoints to induce catastrophic failure of TNBC cells proliferation. Herein, we evaluated the anticancer efficacy of Carbazole Blue (CB), a synthetic analogue of Carbazole, on TNBC cells growth and progression. Our results demonstrated that CB inhibits short and long term viability of TNBC (MDA-MB-231, MDA-MB-468 and BT549) cells in a dose dependent manner without affecting normal mammary epithelial (MCF-10A) cells. In addition, CB treatment significantly reduced proliferation of TNBC cells, as evidenced by the BrdU proliferation assay. Consistent with this, our results further demonstrated that CB treatment induced G1/S cell cycle arrest and apoptosis in TNBCs. Importantly, systemic delivery of CB using nanoparticle-based delivery approach suppressed breast cancer growth without inducing toxicity, in preclinical orthotopic xenograft and PDX mouse models of TNBC. Furthermore, our gene microarray analysis revealed that CB treatment modulates the expression and activity of several genes known to be involved in DNA replication (CDC6, CDT1, MCMs, Claspin, POLE and PCNA) and associated DNA repair machinery such as (XRCC3, Exo1 and RAD51), which play pivotal roles in replication stress. Our results for the first time highlight the potential use of CB as a novel and potent therapeutic agent for treating TNBCs. As exploiting replication stress to treat cancer is gaining major interest, compound/s that may induce replication stress and inhibit DNA repair ability of cancer cells, has immense translational potential.

Citation Format: Rajamanickam S, Park JH, Bates K, Timilsina S, Eedunuri VK, Onyeagucha B, Subbarayalu P, Abdelfattah N, Jung KH, Favours E, Mohammad TA, Chen H-IH, Vadlamudi RK, Chen Y, Kaipparettu BA, Arbiser JL, Rao MK. Targeting replication stress in triple negative breast cancer treatment regimen: An emerging approach [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-06-04.

Retinal Binding to Apo-Gloeobacter Rhodopsin: The Role of pH and Retinal-Carotenoid Interaction

Over the past few decades, the structure, functions, properties, and molecular mechanisms of retinal proteins have been studied extensively. The newly studied retinal protein Gloeobacter rhodopsin (gR) acts as a light-driven proton pump, transferring a proton from the cytoplasmic region to the extracellular region of a cell following light absorption. It was previously shown that gR can bind the carotenoid salinixanthin (sal). In the present study, we report the effect of pH on the binding of retinal to the apo-protein of gR, in the presence and absence of sal, to form the gR pigment. We found that binding at different pH levels reflects the titration of two different protein residues, one at the lower pK_a 3.5 and another at the higher pK_a 8.4, that affect the pigment's formation. The maximum amount of pigment was formed at pH 5, both with and without the presence of sal. The introduction of sal accelerates the rate of pigment formation by a factor of 190. Furthermore, it is suggested that occupation of the binding site by the retinal chromophore induces protein conformational alterations which in turn affect the carotenoid conformation, which precedes the formation of the retinal-protein covalent bond. Our examination of synthetic retinal analogues in which the ring structure was modified revealed that, in the absence of sal, the retinal ring structure affects the rate of pigment formation and that the intact structure is needed for efficient pigment formation. However, the presence of sal abolishes this effect, and all-trans retinal and its modified ring analogues bind at a similar rate.

Temperature dependence of band gap in MoSe2 grown by molecular beam epitaxy

We report on a temperature-dependent band gap property of epitaxial MoSe₂ ultrathin films. We prepare uniform MoSe₂ films epitaxially grown on graphenized SiC substrates with controlled thicknesses by molecular beam epitaxy. Spectroscopic ellipsometry measurements upon heating sample in ultra-high vacuum showed temperature-dependent optical spectra between room temperature to 850 °C. We observed a gradual energy shift of optical band gap depending on the measurement temperature for different film thicknesses. Fitting with the vibronic model of Huang and Rhys indicates that the constant thermal expansion accounts for the steady decrease of band gap. We also directly probe both optical and stoichiometric changes across the decomposition temperature, which should be useful for developing high-temperature electronic devices and fabrication process with the similar metal chalcogenide films.

An evolutionary optimization of a rhodopsin-based phototrophic metabolism in Escherichia coli

Background

The expression of the Gloeobacter rhodopsin (GR) in a chemotrophic Escherichia coli enables the light-driven phototrophic energy generation. Adaptive laboratory evolution has been used for acquiring desired phenotype of microbial cells and for the elucidation of basic mechanism of molecular evolution. To develop an optimized strain for the artificially acquired phototrophic metabolism, an ancestral E. coli expressing GR was adaptively evolved in a chemostat reactor with constant illumination and limited glucose conditions. This study was emphasized at an unexpected genomic mutation contributed to the improvement of microbial performance.

Results

During the chemostat culture, increase of cell size was observed, which were distinguished from that of the typical rod-shaped ancestral cells. A descendant ET5 strain was randomly isolated from the chemostat culture at 88-days. The phototrophic growth and the light-induced proton pumping of the ET5 strain were twofold and eightfold greater, respectively, than those of the ancestral E. coli strain. Single point mutation of C1082A at dgcQ gene (encoding diguanylate cyclase, also known as the yedQ gene) in the chromosome of ET5 strain was identified from whole genome sequencing analysis. An ancestral E. coli complemented with the same dgcQ mutation from the ET5 was repeated the subsequently enhancements of light-driven phototrophic growth and proton pumping. Intracellular c-di-GMP, the product of the diguanylate cyclase (dgcQ), of the descendant ET5 strain was suddenly increased while that of the ancestral strain was negligible.

Conclusions

Newly acquired phototrophic metabolism of E. coli was further improved via adaptive laboratory evolution by the rise of a point mutation on a transmembrane cell signaling protein followed by increase of signal molecule that eventually led an increase proton pumping and phototrophic growth.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-017-0725-6) contains supplementary material, which is available to authorized users.

Abstract P6-01-07: Mitochondria-nuclear communication regulates epithelial-mesenchymal transition and metastasis in triple negative breast cancer

For triple negative breast cancer (TNBC), the driver pathways are still poorly understood. Advances in cancer metabolism research over the last decade have enhanced and modified our understanding on Warburg effect. It is now known that mitochondria in tumors are not always defective in their ability to carry out oxidative phosphorylation. Instead, in proliferating cells, mitochondrial energy pathways are reprogrammed to meet the challenges of macromolecular synthesis and to escape from apoptosis. Tumor initiating cells (TICs) maintain cancer stem cell properties and are known to play significant role in TNBC metastasis. Mitochondrial retrograde regulation (MRR) is a bidirectional communication between mitochondria and nucleus. MRR is triggered by mitochondrial functional demands and it responds in a continuous manner to change metabolic needs of the cell. Using transmitochondrial cybrid (cybrid) technology, we generated different cybrid models under common nuclear backgrounds of benign breast epithelium or TNBC. Mitochondria from cells with different cancer potential such as benign breast epithelium, moderately metastatic and highly metastatic breast cancer cell lines were studied under the common nuclear background to understand MRR-regulated TIC properties and cancer pathways. Using genomic, metabolomic, and proteomic approaches, we confirmed the significance of mitochondrial character in the regulation of epithelial mesenchymal transition (EMT), TIC and metastatic properties. Altogether, our results suggest that MRR is critical in TNBC TIC character and stemness.

Citation Format: Park JH, Jung KH, Sirupangi T, Vithayathil S, Jin F, Putluri V, Piyarathna DWB, Yotnda P, Bhat VB, Sreekumar A, Lewis MT, Coarfa C, Putluri N, Creighton CJ, Wong L-JC, Kaipparettu BA. Mitochondria-nuclear communication regulates epithelial-mesenchymal transition and metastasis in triple negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-01-07.

Abstract P1-02-14: Circulating cell-free DNA (CFD) measured by a simple fluorescent assay to predict relapse in triple negative breast cancer patients receiving neoadjuvant chemotherapy: A biomarker substudy of prospective observational study (NCT02001519, NCT02001506)

Background: Prior technique to measure cell free DNA(CFD) is labor-intensive and expensive, while, recently developed fluorescent CFD assay is more simple and convenient.The aim of this study was to evaluate the role of CFD measured by a fluorescent assay as a biomarker of patients with triple negative breast cancer (TNBC) received neoadjuvant chemotherapy

Methods: We prospectively enrolled patients with TNBC, clinical stage II or III (T>1.5cm or lymph node > 1.5cm), who were scheduled for neoadjuvant chemotherapy. Patients received 4 cycles of adriamycin 60 mg/m2 plus cyclophosphamide 600 mg/m2 (AC) followed by 4 cycles of cisplatin or docetaxel, and surgery. Plasma samples were obtained from patients before initial chemotherapy (baseline-CFD) and after 4 cycles of AC neoadjuvant chemotherapy (AC-CFD).

Results: This study included 72 patients who met the inclusion criteria. The mean levels of baseline-CFD and AC-CFD were 239±68 ng/mL and 210±66 ng/mL, respectively, and the CFD level was significantly decreased after AC chemotherapy.( p=0.001) The baseline-CFD was not associated with initial tumor characteristics. (T stage 1-2 vs. 3, p=0.313; N stage 0 vs. 1-3, p=0.317) There was no statistically significant difference between patients with response (CR or PR) to AC chemotherapy and those without response in terms of baseline-CFD, AC-CFD, and change of CFD between two values. (p=0.814, p=0.839, p=0.927) With 33.6 months of median follow up, there were 18 cases of relapse. Relapsed group showed numerically higher level of baseline-CFD, although it was not statistically significant. (relapse, 259 ng/mL; non-relapse, 233 ng/mL; p=0.161) We performed a ROC curve analysis of baseline-CFD for relapse, and found an area under the curve of 0.62 (95% CI, 0.46-0.78) at 222 ng/mL. Patients with baseline-CFD above 222 showed higher relapses than those below 222. (HR, 2.75; 95% CI, 0.96-7.84; p = 0.059)

Conclusions: The baseline-CFD obtained using a simple and convenient fluorescent assay could predict relapse, suggesting baseline-CFD as a potential biomarker for risk stratification of TNBC.

Citation Format: Park K, Woo M, Kim JE, Ahn J-H, Jung KH, Kim S-B. Circulating cell-free DNA (CFD) measured by a simple fluorescent assay to predict relapse in triple negative breast cancer patients receiving neoadjuvant chemotherapy: A biomarker substudy of prospective observational study (NCT02001519, NCT02001506) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-02-14.

Abstract OT1-01-12: A phase II, multicenter, randomized trial of eribulin plus gemcitabine (EG) vs. paclitaxel plus gemcitabine (PG) in patients with HER2-negative metastatic breast cancer as first-line chemotherapy

Background: Metastatic breast cancer (MBC) is an incurable disease and is needed to improve effective chemotherapy. Paclitaxel plus Gemcitabine (PG) combination chemotherapy is one of the preferred chemotherapeutic regimens for patients with MBC, and was found to be proper as a maintenance chemotherapy regimen with survival benefit and feasible toxicity profile. Eribulin mesylate is a non-taxane inhibitor of microtubule dynamics of the halichondrin class of antineoplastic drugs. A recent pooled analysis of two phase II studies with eribulin showed improved overall survival in in various patient subgroups with advanced/metastatic breast cancer who had previously received an anthracycline and a taxane. Furthermore, eribulin may have rational benefit compared with paclitaxel in terms of neurotoxicity. Therefore, Eribulin plus Gemcitabine (EG) combination chemotherapy may have less neurotoxocity comparing to PG.

Trial Design: Prospective randomized phase 2, open-label, two-arm, multi-center study comparing EG chemotherapy with PG chemotherapy for patients with HER-2 negative MBC as first-line chemotherapy.

Eligibility Criteria: Histologically confirmed breast cancer patients, at least 19 years of age, with no prior history of chemotherapy for metastatic, recurrent breast cancer with evaluable lesions (as per RECIST, 1.1) who have adequate hematologic, renal, and hepatic function. Patients either may or may not have a prior anthracycline containing regimen. Prior hormonal therapy as a treatment of metastatic disease is allowed.

Specific Aims:

The primary efficacy endpoint of the trial is Progression-Free Survival (PFS). The secondary efficacy endpoints are: Time to Treatment Failure (TTF); Overall Survival (OS); neuropathic scale (FACT for Taxane QOL assessment); toxicity; duration of response; Objective Response Rate (ORR); Clinical Benefit Rate. The exploratory endpoint of the study includes pharmacogenetic profile.

Statistical Methods:

The initial sample size of the present study was determined based on the data derived from a previous trial on PG maintenance chemotherapy design; 6-month PFS is 70% for PG chemotherapy. This design was hypothesized that EG chemotherapy would not be inferior to PG chemotherapy. Thus, estimated PFS for each arm is 70%. Based on this estimate, we would plan to recruit a total of 100 patients (50 per arm). Considering drop-out rate of 10%, total 112 MBC patients planned to be enrolled.

Present Accrual and Target Accrual:Enrollment has been completed as of March, 2016 with a target enrollment of 112 patients.

Contact information:Kyung Hae Jung MD, Ph.D. khjung@amc.seoul.kr

ClinicalTrials.gov Identifier: NCT02263495.

Citation Format: Park YH, Im S-A, Sohn JH, Lee KS, Chae YS, Lee KH, Kim J-H, Im Y-H, Ahn JS, Kim T-Y, Lee K-H, Kim S-B, Ahn J-H, Kim GM, Park IH, Lee SJ, Han HS, Kim SH, Jung KH. A phase II, multicenter, randomized trial of eribulin plus gemcitabine (EG) vs. paclitaxel plus gemcitabine (PG) in patients with HER2-negative metastatic breast cancer as first-line chemotherapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT1-01-12.

A randomized, multi-center, open-label, phase III study of once-per-cycle DA-3031, a pegylated G-CSF, in comparison with daily filgrastim in patients receiving TAC chemotherapy for breast cancer

PURPOSE

This multi-center, randomized, phase III study was conducted to demonstrate the non-inferiority of DA-3031 compared with daily filgrastim in patients during the first cycle of chemotherapy for breast cancer in terms of the duration of severe neutropenia (DSN).

METHODS

Seventy-four patients with breast cancer who were receiving combination chemotherapy with docetaxel, doxorubicin, and cyclophosphamide (TAC) were enrolled. All participants were randomized to receive either daily subcutaneous injections of filgrastim 100 μg/m²/day for up to 10 days or a single subcutaneous injection of DA-3031 at fixed doses of 6 mg on day 2 of each chemotherapy cycle.

RESULTS

The mean duration of grade 4 (G4) neutropenia in cycle 1 was 2.08 ± 0.85 days for the filgrastim group and 2.28 ± 1.14 days for the DA-3031 group. The difference between groups was 0.2 ± 1.10 days (95 % confidence interval (CI) = -0.26, 0.66), which supported non-inferiority. No statistically significant differences were observed in nadir absolute neutrophil count (ANC) (154.34/mm³ and 161.75/mm³ for the filgrastim and DA-3031 groups, respectively; P = 0.8414) or in time to ANC recovery (10.03 ± 0.75 and 9.83 ± 1.56 days in the filgrastim and DA-3031 groups, respectively; P = 0.0611) during cycle 1. Serious AEs occurred in six (15.8 %) patients receiving filgrastim and in ten (27.8 %) patients receiving DA-3031; however, none was determined to be related to the study drug.

CONCLUSIONS

DA-3031 and daily filgrastim are similar in regard to DSN and safety in breast cancer patients receiving TAC chemotherapy.

Abstract P1-09-09: Role of endocrine therapy in premenopausal patients with hormone receptor-positive metastatic breast cancer, compared with postmenopausal patients: Diachronic analyses from nationwide cohort in Korea (KCSG BR 14-07)

Background

Endocrine therapy (E) has a major role in treatment of hormone receptor (HR)-positive metastatic breast cancer (MBC). However, in contrast to western countries, premenopausal patients (PRE) more prevalent (50% of all breast cancer patients) and have less options of E than postmenopausal patients (POST) in Korea where the use of LHRH agonist in combination aromatase inhibitors (AIs) in PRE is restricted. Recently we have been successfully established nationwide cohort for the patients MBC (575 patients from 26 institutes). This study was designed to evaluate the role of E especially in PRE.

Methods

The patients with MBC were prospectively or retrospectively enrolled between September 2014 and May 2015. Only menopausal status-confirmed patients (296) were analyzed. Postmenopause was defined, based on NCCN guideline. Total duration of treatment was defined as the time from start day of any first treatment to end of any last treatment. Total duration of E was defined as the sum of time duration of each E. Overall survival was calculated from the start day of any treatment for MBC to any causes of death. This work is supported by National Strategic Coordinating Center for Clinical Research (H110C2020).

Results

A total of 296 patients with HR-positive MBC were analyzed [PRE, 169 (57.1%) and POST, 127 (42.9%)]. Except age (mean 44 and 60 years), baseline characteristics including in pathology, HER2 status, initial pathologic stage, de novo metastasis versus recurrence, surgery and adjuvant treatment (chemotherapy, endocrine therapy and radiotherapy) were well balanced. 92 (54.4%) of PRE and 77 (60.6%) of POST received at least one or more E through all treatment course. 41 (24.2%) of PRE and 44 (34.6%) received E as 1st-line treatment (p=0.034). Among PRE who received 1st-line of E, 30 (71.4%) and 9 (21.4%) of PRE received 2nd- and 3rd-line E. 20 (45.4%) and 10 (22.7%) of POST received 2nd- and 3rd- or more line of E. Most of PRE (54%) received tamoxifen+/-goserelin and 32% of PRE received AIs along with ovarian suppression. 71% of POST received AIs. As initial treatment, E was more frequently used in POST than in PRE (34.6% and 24.3%, p=0.053). Overall survival (OS) of all patients was 18.2 months (95% CI, 14.8-21.5). There was no difference in OS between PRE (17.8 months, 10.9-24.8) and POST (18.5 months, 95% CI, 13.2-23.9) (P=0.337). No difference of OS was observed (E, 18.1 moths, 95% CI, 13.0-23.3; chemotherapy 21.2 moths, 95% CI, 16.8-25.5), regardless of initial treatment. Total duration of treatment of PRE and POST were 15.2 and 13.6 months, respectively with no significant difference (p=0.389). PRE (8.3 moths, 95% CI,5.7-10.8) showed the trend toward longer duration of E in comparison with POST (5.5 moths, 95% CI,4.4-6.7), however the difference did not reach statistical significance (p=0.051).

Conclusion

E was more commonly used as 1st-line therapy in POST than in PRE. Although PRE had limited options of E, E was used in long duration of treatment especially in PRE. These findings suggested that E had a role in treatment for PRE with HR-positive MBC and could be used in treatment for PRE with good efficacy.

Citation Format: Kim T-Y, Ahn J-H, Yoon JH, Sohn JH, Kim GM, Lee KH, Park YH, Koh S-J, Lee SE, Chae Y, Lee KS, Lee KE, Won HS, Kim JH, Jeong J, Park KH, Cho EK, Im Y-H, Im S-A, Jung KH. Role of endocrine therapy in premenopausal patients with hormone receptor-positive metastatic breast cancer, compared with postmenopausal patients: Diachronic analyses from nationwide cohort in Korea (KCSG BR 14-07). [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 P1-09-09.

Abstract P3-07-34: Predictive role of stromal tumor infiltrating lymphocytes (TILs) in patients with metastatic HER2-positive breast cancer (BC) treated with trastuzumab

Background:Prognostic significance of stromal TILs in metastatic BC has been suggested in various BC subtypes. However, predictive role of stromal TILs for the efficacy of trastuzumab has not been established in patients with HER2-positive BC. This study was performed to evaluate whether the stromal TILs are associated with the efficacy of trastuzumab in patients with metastatic HER2-positve BC.

Method:Between June 2006 and March 2013, a total of 60 women with recurrent or metastatic HER2-positive BC treated with trastuzumab were included in this retrospective analysis. In these patients, trastuzumab was administered either as single agent or combination with taxanes. Stromal TILs were assessed using immunohistochemistry in surgical specimen (n=39, 65%) and biopsy specimen of metastatic lesion (n=21, 35%) by the academic pathologist (HJL). Primary endpoint of this study was progression-free survival (PFS), and secondary endpoints were response rate and overall survival (OS).

Result:Median age was 54 year old (range, 36-76), and all patients had invasive ductal carcinoma. Hormone receptor was positive in 34 patients (57%) and 18 patients (30%) initially presented with metastatic disease. Nine patients (15%) received cytotoxic chemotherapy without trastuzumab before the administration of trastuzumab. Patients were grouped according to the TILs (< 10% [n=50] and >10% [n=10]), and there was no significant difference in age (p=0.68), histologic grade (p=1.00), metastatic sites (p>0.05), and number of lines of chemotherapy before the administration of trastuzumab(p=0.33) among patients with low and high stromal TILs. High TILs were more common in hormone receptor (HR)-negative tumor compared with HR–positive tumor (31% vs 6%; p=0.02). In overall, median PFS and OS were 15.0 months (95% CI, 9.7-20.2) and 35.0 months (95% CI, 29.8-40.2), respectively. Median PFS in patients with high stromal TILs were numerically longer than that in those with low TILs (22.0 months [95% CI, 9.6-34.4] vs 14.0 months [95% CI, 9.6-18.4]; p=0.057). There was no difference in response rates (p=0.43) and OS (p=0.94) according to the stromal TILs. FcR genotype was not significantly correlated with objective response rate, PFS and OS.

Conclusion:This study suggests that the stromal TILs might be associated with the clinical outcomes of HER2-targeted therapy in patients with metastatic HER2-positive BC. Our finding should be validated in future studies based on a large sample size.

Keywords: Breast cancer, tumor infiltrating lymphocyte. Trastzumab, HER2.

Citation Format: Yoon JA, Yoo C, Lee HJ, Kim K-P, Kim J, Ahn J-H, Jung KH, Gong G, Kim S-B. Predictive role of stromal tumor infiltrating lymphocytes (TILs) in patients with metastatic HER2-positive breast cancer (BC) treated with trastuzumab. [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 P3-07-34.

Abstract P1-14-15: A randomized phase lll trial of neoadjuvant sequential chemotherapy with 4 cycles of adriamycin plus cyclophosphamide followed by 4 cycles of docetaxel (AC4-D4) versus shorter 3 cycles of FEC followed by 3 cycles of docetaxel (FEC3-D3) in node-positive breast cancer (Neo-Shorter): First report of efficacy & toxicity profile

Background: The addition of a taxane to anthracycline-based chemotherapy provided an improved outcome in neoadjuant setting. Two neoadjuvant chemotherapy with 4 cycles of AC followed by 4 cycles of docetaxel (AC4-D4) and 3 cycles of FEC followed by 3 cycles of docetaxel (FEC3-D3) are widely used. Short duration of chemotherapy, 6 cycles rather than 8 cycles might be an attractive approach.

Methods: This is a randomized, single-center, prospective, parallel group, comparative phase III trial (NCT02001506). Patients (pts) with breast cancer of clinically stage II or III, or sized  1.5 cm with histologically proven lymph-node involvement were included. Pts were stratified according to hormone receptor and HER2 expression status and randomized to AC4-D4 and 3 cycles of FEC3-D3 treatment. The primary endpoint was pathological complete response, defined as the absence of invasive disease in the breast and axillary lymph nodes, analyzed by intention to treat.

Results: At the time of submission, a total of 207 pts were enrolled; 1 pt failed screening; 25 pts dropped out (5 pts in AC4-D4 arm and 2 pts in FEC3-D3 arm discontinue treatment due to progressive disease); 39 pts are still receiving neoadjuvant chemotherapy; 142 pts, who received surgery, were included for this analysis. In AC4-D4 arm, among 64 pts, 57 pts achieved clinical response (6 complete response [CR] and 51 partial response [PR]) and among them 9 pts achieved pathologic complete response [pCR]. In FEC3-D3 arm, among 78 pts, 66 pts achieved clinical response (7 CR and 59 PR) and among them 11 pts achieved pCR. Addition of docetaxel increased clinical response in both arms. The most common adverse event was febrile neutropenia. Without prophylactic G-CSF, grade ≥3 febrile neutropenia (FN) occurred 23/661 cycles (3.5%) in AC4-D4 arm and 23/552 cycles (4.2%) in FEC3-D3 arm, respectively. Grade 3 and 4 toxicities other than FN were reported at expected levels in both groups. Sixty-one severe adverse events were reported; 33 (including 23 FN) in AC4-D4 arm and 28 (including 23 FN) in FEC3-D3 arm.

Conclusion: Compared to AC4-D4, shorter duration of FEC3-D3 neoadjuvant chemotherapy showed similar efficacy of pCR rate of 14.0% (versus 14.1% in AC4-D4 arm). The most common and important adverse event was febrile neutropenia in both arms. Updated study findings will be provided.

Citation Format: Kim JE, Ahn J-H, Jung KH, Lee HJ, Gong G-Y, Lee E-M, Ha EJ, Son B-H, Ahn S-H, Ahn SD, Kim H-H, Shin HJ, Kim S-B. A randomized phase lll trial of neoadjuvant sequential chemotherapy with 4 cycles of adriamycin plus cyclophosphamide followed by 4 cycles of docetaxel (AC4-D4) versus shorter 3 cycles of FEC followed by 3 cycles of docetaxel (FEC3-D3) in node-positive breast cancer (Neo-Shorter): First report of efficacy & toxicity profile. [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 P1-14-15.

Abstract P6-10-03: Does participation in clinical trials influence on survival in patients with metastatic breast cancer?

Background

Recently, many clinical trials (TRIAL) especially incorporated with molecular-targeted agents are being conducted in treatment for breast cancer worldwide. However, the relation of participating clinical trials with survival has not been actively studied. This study was designed to evaluate whether participation in clinical trials could improve overall survival (OS) or not in patients with metastatic breast cancer (MBC), compared with conventional treatment.

Method

Korean Cancer Study Group (KCSG) has successfully established Nationwide Cohort in KOREA to conduct diachronic analysis (KCSG BR 14-07). Clinical data for patients with MBC were collected from this Cohort. OS was defined as the time duration from first diagnosis of metastasis to any cause of death. This work is supported by National Strategic Coordinating Center for Clinical Research (H110C2020).

Results

A total of 575 patients with metastatic breast from 26 institutes in KOREA cancer MBC were consequently enrolled between September 2014 and May 2015. 156 (27.1%) of patients were enrolled to at least one or more clinical trials and 419 patients received only conventional treatment (CONV). Age, hormone status, HER2 status, initial pathologic stage, metastasis versus recurrence, adjuvant treatment, ECOG performance status (PS) (0, 1 vs 2 or more) were similar between TRIAL and CONV. 30% of trials were associated with HER2-targeted agents. As initial treatment, chemotherapy was more frequently used in TRIAL (85.9%) than in CONV (79.0%) (P=0.038). Number of regimens of chemotherapy was greater in TRIAL (2.9+/-1.8) than CONV (2.1+/-1.6) (P<0.001). Number of regimens of endocrine therapy (E) was similar between TRIAL (1.4+/-0.6) and CONV (1.5+/-0.7) (P=0.474). Overall survival of all patients was 16.2 months (95% CI, 14.1-18.1). TRIAL showed significant prolongation of survival, compared with CONV [21.1 (95% CI, 17.7-24.6) vs 15.1 months (95% CI, 13.1-17.2); P=0.005]. The differences in OS was constantly observed in HER2-positive [23.8 (16.7-30.9) vs 17.2 months (95% CI, 12.4-21.9); P=0.018] and Triple-negative [15.4 (10.5-20.3) vs 12.0 months (95% CI, 10.2-13.8); P=0.025]. In multivariate analysis, initial metastasis, hormone status, ECOG PS did not influence on OS between TRIAL and CONV (P=0.849)

Conclusion

Participating in clinical trials could be associated with prolongation of survival. This results constantly maintained in HER2-positive and triple-negative MBC. These findings suggested that clinical trials are useful for the patients with MBC, even if the patients do not complete the standard treatment.

Citation Format: Kim T-Y, Sohn JH, Kim S-B, Yoon JH, Kim GM, Lee KH, Koh S-J, Park YH, Lee SE, Chae Y, Lee KS, Lee KE, Won HS, Kim JH, Jeong J, Park KH, Cho EK, Im Y-H, Im S-A, Jung KH. Does participation in clinical trials influence on survival in patients with metastatic breast cancer?. [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 P6-10-03.

Abstract OT3-01-10: A prospective, open-label, single-arm, multi-center, phase II exploratory study to evaluate the efficacy and safety of poziotinib (NOV120101) in patients with HER2-positive metastatic breast cancer who have received at least two prior HER2-directed regimens

Background: Poziotinib is a novel, oral, irreversible pan-HER inhibitor that has shown promising clinical activity in Phase 1 studies of patients (pts) with advance HER2 positive breast cancer who have failed at least 2 prior lines of HER2-directed therapy. A Phase 2 study of poziotinib was initiated in Korea in March 2015 in pts with HER2+ metastatic breast cancer. This phase 2 study is designed to seek accelerated approval for poziotinib for the treatment of metastatic breast cancer in Korea.

Trial Design: Prospective Phase 2, open-label, single-arm, multi-center study in pts with recurrent, Stage IV breast cancer with HER2-overexpression who had received at least 2 prior HER2-directed regimens

Eligibility Criteria: Histologically confirmed breast cancer patients, at least 19 years of age, with confirmed HER2 positive evaluable tumors (per RECIST, 1.1) who have adequate hematologic, renal, and hepatic function and have failed at least two HER2-directed regimens that included a taxane-containing anticancer chemotherapy, with a life expectancy of at least 12 weeks.

Specific Aims: The Primary Efficacy Endpoint of the study was Progression-Free Survival (PFS). The Secondary Efficacy Endpoints included: PFS rate at 12 weeks post-dose; Objective Response Rate (ORR) including Complete Response (CR) and Partial Response (PR) rates; Disease Control Rate (DCR) including CR, PR, and Stable Disease (SD); Duration of Disease Control; Overall Survival (OS); Time to Progression (TTP); Time to Objective Response and Duration of Objective Response. The Exploratory Endpoints included: Population Pharmacokinetic (PK) Profile and Exploratory Genomic and Biomarker Analyses.

Statistical Methods: In the randomized, multicenter, 2-arm, open-label study of trastuzumab emtansine (TH3RESA18), the median PFS was shown to be 3.3 months in subjects with optimal treatment per Investigator's Choice. This ongoing study with poziotinib expects a median PFS of 4.5 months based on data from a previous Phase 1 study of poziotinib (NOV120101). Based on the following assumptions, a 5% one-sided significance level, and 80% power, and 2 months of accrual and 12 months of follow-up, 66 subjects will be required. Accounting for a 10% drop-out rate, a total of 74 subjects will be recruited into this ongoing Phase 2 study.

Present Accrual and Target Accrual: 17 patients enrolled as of May 20, 2015 with a total target enrollment of 74 patients

Contact information:

ClinicalTrials.gov Identifier: NCT02418689.

Citation Format: Park Y-H, Jung KH, Sohn JH, Lee KS, Lee KH, Kim J-H, Kim J-Y, Jung J, Han H, Park W-Y, Im S-A. A prospective, open-label, single-arm, multi-center, phase II exploratory study to evaluate the efficacy and safety of poziotinib (NOV120101) in patients with HER2-positive metastatic breast cancer who have received at least two prior HER2-directed regimens. [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 OT3-01-10.

Structural basis for the slow photocycle and late proton release in Acetabularia rhodopsin I from the marine plant Acetabularia acetabulum

Although many crystal structures of microbial rhodopsins have been solved, those with sufficient resolution to identify the functional water molecules are very limited. In this study, the Acetabularia rhodopsin I (ARI) protein derived from the marine alga A. acetabulum was synthesized on a large scale by the Escherichia coli cell-free membrane-protein production method, and crystal structures of ARI were determined at the second highest (1.52–1.80 Å) resolution for a microbial rhodopsin, following bacteriorhodopsin (BR). Examinations of the photochemical properties of ARI revealed that the photocycle of ARI is slower than that of BR and that its proton-transfer reactions are different from those of BR. In the present structures, a large cavity containing numerous water molecules exists on the extracellular side of ARI, explaining the relatively low pK a of Glu206ARI, which cannot function as an initial proton-releasing residue at any pH. An interhelical hydrogen bond exists between Leu97ARI and Tyr221ARI on the cytoplasmic side, which facilitates the slow photocycle and regulates the pK a of Asp100ARI, a potential proton donor to the Schiff base, in the dark state.

Mistic-fused expression of algal rhodopsins in Escherichia coli and its photochemical properties

BACKGROUND

Since algal rhodopsins, the eukaryotic seven-transmembrane proteins, are generally difficult to express in Escherichia coli, eukaryotic cells have been used for heterologous expression. Mistic, a membrane-associated protein that was originally discovered in Bacillus subtilis, has been shown to improve the expression levels of many foreign integral membrane proteins in E. coli when used as a fusion partner linked to the N-terminus of cargo proteins.

METHODS

Here, we expressed two algal rhodopsins with N- and C-terminal Mistic domains in E. coli-Acetabularia rhodopsin I (ARI) and Chlamydomonas sensory rhodopsin B (CSRB, channel rhodopsin 2). UV/VIS spectroscopy, pH titration of proton acceptor residue, laser-induced photolysis and electrophysiological measurement were used for investigating important residues in proton transport and spectroscopic characters of the proteins.

RESULTS

Protein yield of two algal rhodopsins was enhanced, obtaining 0.12mg of Mistic-ARI and 0.04mg of Mistic-CSRB per liter of culture. Spheroplast expression Mistic-ARI had outward proton-pumping activity, indicating protein functionality. Asp89 of ARI changed its protonation state by light absorption, and Asp100 was important for O(600) formation. Electrophysiology revealed that both residues took part in proton transport. The spectroscopic analyses of Mistic-CSRB revealed its characteristics.

CONCLUSIONS

Fusion to the membrane-integrating protein Mistic can enhance overexpression of eukaryotic type I rhodopsins in E. coli.

GENERAL SIGNIFICANCE

These findings indicate that Mistic fusion and E. coli expression method could be an effective, low cost technique for studying eukaryotic membrane proteins. This may have useful implications, for example, in studying structural characteristics and optogenetics for rhodopsins.