Abstract P5-03-08: Eribulin-induced EpCAM expression provides drug resistance in triple-negative breast cancer cells

Breast cancer is the most common cancer in women in the world. Among breast cancer subtypes, triple-negative breast cancer is aggressive. Because there is no effective therapy for triple-negative breast cancer, development of a novel therapeutic strategy is required.

Eribulin, a derivative of halicondrin B, is an anticancer chemical. Eribulin treatment has been approved in many countries for patients with metastatic or inoperable breast cancer, including triple-negative breast cancer. The known functions of Eribulin are inhibition of microtubule polymerization and induction of the expression of epithelial genes in breast cancer cells. However, the function of Eribulin-induced genes on the therapy for patients with triple-negative breast cancer remains unclear.

EpCAM (Epithelial cell adhesion molecule) is one of epithelial markers and known as a cell-cell adhesion molecule. In addition, EpCAM expression is involved in drug resistance in cancer. We therefore focused on EpCAM expression in Eribulin-treated breast cancer cells.

We used MDA-MB-231 cells that is a commonly used triple-negative breast cancer cell line. We treated cells with 10 nM Eribulin and observed inhibition of cell growth. In the same condition, we found up-regulation of EpCAM expression in both mRNA and protein levels. In mouse xenograft model with MDA-MB-231 cells, EpCAM expression was detected in whole tumor at 96 h after Eribulin administration. We analyzed the effect of other microtubule polymerization inhibitors, nocodazole and colchicine, on EpCAM induction. In the results, there was no up-regulation of EpCAM expression in cells treated with these chemicals, suggesting that EpCAM expression is not induced by inhibition of microtubule polymerization and growth inhibition.

To analyze EpCAM function on Eribulin treatment, we constructed shRNA-mediated EpCAM knockdown system. We introduced EpCAM knockdown in MDA-MB-231 cells and treated with Eribulin. In the results of cell growth assays, the cell number of Eribulin-treated EpCAM-knockdown cells was significantly smaller than that of Eribulin-treated control-shRNA cells, whereas no change was observed between solvent-treated control-shRNA and EpCAM-knockdown groups. In mouse xenograft experiments, EpCAM-knockdown cells showed smaller tumor weights than control-shRNA cells after administration of Eribulin. These results indicate that EpCAM expression provides Eribulin resistance in breast cancer cells.

In conclusion, we found Eribulin-induced EpCAM expression in triple-negative breast cancer cells. The EpCAM expression provides Eribulin resistance both in vitro and in vivo. These suggest that a combination of Eribulin treatment and EpCAM inhibition may improve therapy for breast cancer.

Citation Format: Tanaka S, Itou J, Sato F, Toi M. Eribulin-induced EpCAM expression provides drug resistance in triple-negative breast cancer cells [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-03-08.

Abstract P2-01-11: A peptide with the conserved amino acid residue of integrin α6 inhibits metastasis through disruption of complex formation in breast cancer cells

Metastasis inhibition may improve survival of breast cancer patients. Our previous study revealed that a transcription factor SALL4 promotes cell migration for metastasis through up-regulation of integrin α6β1 in metastatic basal-like breast cancer cells. In these cells, integrin α6β1 modulates Rho GTPase activity, which enhances focal adhesion dynamics for cell migration. We therefore focused on integrin α6 as a therapeutic target for metastasis.

We investigated the expression level of integrin α6 in breast cancer cell lines and a tissue microarray of breast cancer patients. In both experiments, we observed higher integrin α6 expression in basal-like breast cancer cells than in luminal ones. We performed shRNA-mediated integrin α6 knockdown in basal-like breast cancer cells and conducted Boyden chamber assays. In the results, reduced cell migration was observed in integrin α6 knocked-down cells. Reciprocally, we introduced integrin α6 overexpression in low-migratory luminal breast cancer cell lines and observed increased cell migration. These results indicate that integrin α6 promotes cell migration in breast cancer cells.

To identify the functional residue of integrin α6, we analyzed its amino acid sequence by in silico analyses. First, we extracted integrin α6 specific residues in integrin α family in the human genome. Then, we compared integrin α6 sequences among vertebrates. In the result, we obtained an integrin α6-specific and vertebrate-conserved sequence, Asp-358, as a candidate for the functional residue.

To inhibit integrin α6 function, we designed an 8-amino acid peptide with the sequence around Asp-358. Basal-like breast cancer cells treated with the peptide showed reduced cell migration in a dose-dependent manner. The peptide did not reduce cell migration in integrin α6 knocked-down cells, suggesting that the peptide inhibits integrin α6 function. To determine whether the peptide inhibits metastasis, we performed zebrafish metastasis assays, and observed reduced metastasis rate in the peptide-treated group. These results indicate that the peptide inhibits metastasis through reduction in cell migration.

To understand the effect of the peptide, we performed chemical cross-liking assay in a basal-like breast cancer cell line. Protein samples from the cells treated with a cross-linker showed bands of integrin α6 complexes, and the intensities of these bands were reduced in the peptide-treated group. Moreover, we immunostained cells with an antibody for focal adhesion marker, phospho-paxillin, because integrins regulates focal adhesion formation for cell migration. In the results, the peptide reduced the number of focal adhesions. These observations indicate that the peptide inhibits integrin α6 function. In the future, our findings may contribute to development of a metastasis inhibition therapy.

Citation Format: Itou J, Tanaka S, Senda N, Iida A, Sehara-Fujisawa A, Sato F, Toi M. A peptide with the conserved amino acid residue of integrin α6 inhibits metastasis through disruption of complex formation in breast cancer cells [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 P2-01-11.

DESIGN IMPROVEMENT OF A LIQUID-MODERATOR-BASED NEUTRON SPECTROMETER FOR BNCT

Boron neutron capture therapy is known to be an effective radiation cancer therapy that requires neutron irradiation. A neutron field generated by an accelerator-based neutron source has various energy spectra, and it is necessary to evaluate the neutron spectrum in the treatment field. However, the method used to measure the neutron spectrum in the treatment field is not well established. Many researchers are making efforts to improve the spectrometers. To solve this problem, we are developing a liquid-moderator-based neutron spectrometer that is based on the same theory as that of the Bonner sphere spectrometer. The spectrometer uses a liquid moderator and absorber. In the present study, we performed a design study to improve the previously developed liquid-moderator-based neutron spectrometer. By carrying out a numerical simulation of the designed new spectrometer, we finally assessed and confirmed the validity of this spectrometer numerically.

Abstract PD2-07: Real-time navigation for sentinel lymph node biopsy in breast cancer patients using projection mapping with indocyanine green fluorescence

Background)

Sentinel lymph node (SLN) biopsy using indocyanine green fluorescence (fICG) method showed equal or better identification rate compared with blue dye or radioisotope (RI) method. In the fICG method, lymphatic vessels which drain into the SLNs can be seen through skin or subcutaneous tissue using near infrared camera (Photodynamic Eye®: PDE), and we can easily find the SLNs. However, whenever we observe the fluorescence images, we have to hold the PDE, turn off the operating light, and look at a monitor because fluorescence images cannot be seen directly. Medical imaging projection system (MIPS) is a new device which detects fluorescent emission from the organ and projects their images on the location of the fluorescence emission (Panasonic Connected Solutions Company, Japan). Projected images can be adjusted following the body movement or deformation of the organ. Therefore, MIPS could provide an option for real-time navigation for the SLN biopsy. The aim of this study was to evaluate the clinical utility of the MIPS.

Patients and methods)

Patients with clinically node-negative primary breast cancer underwent the fICG SLN biopsy using MIPS. Primary endpoint was identification rate of the fICG method using MIPS. At first, the study was conducted as an interventional study because the MIPS was the unapproved medical device. After approval of the MIPS, this study was conducted as an observational study. The study protocol was approved by the institutional review board at Kyoto University Hospital. All patients provided informed consent to participate in this study.

Results)

Between March 2016 and May 2017, 39 patients (40 procedures) underwent the fICG method SLN biopsy using MIPS. The median age was 55 years (range 32–74 years), and the median body mass index was 20.4 kg/m2 (range 17.7–27.7 kg/m2). About half had tumor stage T1 (58%) and 8 (20.0%) had DCIS. 8 procedures (20%) were performed after preoperative systemic therapy (PST). As MIPS itself can illuminate the operating field, SLN biopsy using MIPS was successfully performed without operating light in all procedures. At least one SLN was detected using MIPS for all procedures and the identification rate was 100% (95% CI: 91–100%). Median number of SLNs detected by MIPS was 3 (range 1–9) for all procedures, and 3 (range 2–8) for procedures after PST. Two pathologically positive SLNs and one SLN which included isolated tumor cells were detected by MIPS. In 25 procedures, RI was also used. 62 of 97 SLNs detected by MIPS (64%) were also detected by RI. However, no SLNs were detected only by RI.

Conclusions)

Although we still may not be able to avoid RI method because 25/40 (62.5%) procedures required the combined use of RI method, the fICG methods SLN biopsy using MIPS, which showed comparable identification rate of SLN with the conventional methods, could be useful tool with a view of allowing us to perform a real-time navigation surgery.

Acknowledgements)

This study was supported by Acceleration Transformative research for Medical innovation, Japan Agency for Medical Research and Development (AMED).

Citation Format: Takada M, Takeuchi M, Suzuki E, Sato F, Matsumoto Y, Torii M, Sakita-Kawaguchi N, Nakayama Y, Okuda T, Nishino H, Seo S, Hatano E, Toi M. Real-time navigation for sentinel lymph node biopsy in breast cancer patients using projection mapping with indocyanine green fluorescence [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 PD2-07.

DEVELOPMENT OF ISOTOPICALLY ENRICHED BORON-DOPED ALUMINA DOSIMETER FOR THERMAL NEUTRONS

A novel optically stimulated luminescence (OSL) detector containing isotopically enriched boron was developed for thermal neutron dosimetry. Alumina containing isotopically enriched boron (Al2O3:B) was synthesised by the sol-gel method. The Al2O3:B was annealed up to ~1800 K. For X-ray diffractometer (XRD) analysis, the diffraction pattern of the Al2O3:B had reflex peaks corresponding to α-Al2O3. The sensitivity of Al2O3:B to photons was slightly 2% of that of a commercial Al2O3:C. The Al2O3:B detector had satisfactory linearity in X-ray dose measurement. A thermal neutron field was constructed using a 241Am-Be neutron source and graphite blocks. A pair of Al2O3:10B and Al2O3:11B detectors were set in the thermal neutron field. The response of Al2O3:10B was larger than that of Al2O3:11B owing to the 10B(n,α)7Li reactions. The sensitivity of Al2O3:10B to thermal neutrons was estimated to be two orders less than the photon sensitivity. Therefore, the pair of Al2O3:10B and Al2O3:11B detectors were useful for thermal neutron dosimetry.

Measurement of urinary concentrations of the mycotoxins zearalenone and sterigmatocystin as biomarkers of exposure in mares

Mycotoxins may affect animal health, including reproduction. Little is known about the clinical relevance of exposure of horses to contaminated feed. This study aimed at (i) monitoring the levels of the mycotoxins zearalenone (ZEN), with its metabolites α- and β-zearalenol (α- and β-ZOL), and sterigmatocystin (STC) in urine samples from thoroughbred mares in Japan and (ii) relating these findings to the potential effects on reproductive efficacy of breeding mares. Sixty-three urine samples of breeding mares from 59 breeding farms were used. Urine samples and reproductive records were collected from each mare when it was presented to the stallion station. Urinary concentrations of ZEN, α- and β-ZOL, and STC were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). ZEN, α- and β-ZOL were measurable in the urine of all examined mares, indicating the prevalence of ZEN in equine feeds. In seven of the 63 samples, STC was also detected at levels ranging from 1.3 to 18.0 pg/mg creatinine. No significant correlation between the concentrations of mycotoxins and pregnancy status was observed. In conclusion, measurement of mycotoxins in urine samples is a useful non-invasive method for monitoring the systemic exposure of mares to multiple mycotoxins.

Variability and constraint of vertebral formulae and proportions in colugos, tree shrews, and rodents, with special reference to vertebral modification by aerodynamic adaptation

BACKGROUND

The aim of the present study is to provide the first large data set on vertebral formulae and proportions, and examine their relationship with different locomotive modes in colugos (Dermoptera), tree shrews (Scandentia), and rodents (Rodentia), which have been considered less variable because they were thought to have a plesiomorphic number of 19 thoracolumbar vertebrae.

MATERIALS AND METHODS

The data included 33 colugos and 112 tree shrews, which are phylogenetically sister taxa, and 288 additional skeletons from 29 other mammalian species adapted to different locomotive modes, flying, gliding, arboreal, terrestrial, digging, and semi-aquatic habitats.

RESULTS

The following results were obtained: (1) intra-/interspecies variability and geographical variation in thoracic, lumbar, and thoracolumbar counts were present in two gliding colugo species and 12 terrestrial/arboreal tree shrew species; (2) in our examined mammals, some aerodynamic mammals, such as colugos, southern flying squirrels, scaly-tailed squirrels, and bats, showed exceptionally high amounts of intraspecific variation of thoracic, lumbar, and thoracolumbar counts, and sugar gliders and some semi-aquatic rodents also showed some variation; (3) longer thoracic and shorter lumbar vertebrae were typically shared traits among the examined mammals, except for flying squirrels (Pteromyini) and scaly-tailed squirrels (Anomaluridae).

CONCLUSIONS

Our study reveals that aerodynamic adaptation could potentially lead to strong selection and modification of vertebral formulae and/or proportions based on locomotive mode despite evolutionary and developmental constraints. (Folia Morphol 2018; 77, 1: 44-56) Background: The aim of the present study is to provide the first large data set on vertebral formulae and proportions, and examine their relationship with different locomotive modes in colugos (Dermoptera), tree shrews (Scandentia), and rodents (Rodentia), which have been considered less variable because they were thought to have a plesiomorphic number of 19 thoracolumbar vertebrae.

MATERIALS AND METHODS

The data included 33 colugos and 112 tree shrews, which are phylogenetically sister taxa, and 288 additional skeletons from 29 other mammalian species adapted to different locomotive modes, flying, gliding, arboreal, terrestrial, digging, and semi-aquatic habitats.

RESULTS

The following results were obtained: (1) intra-/interspecies variability and geographical variation in thoracic, lumbar, and thoracolumbar counts were present in two gliding colugo species and 12 terrestrial/arboreal tree shrew species; (2) in our examined mammals, some aerodynamic mammals, such as colugos, southern flying squirrels, scaly-tailed squirrels, and bats, showed exceptionally high amounts of intraspecific variation of thoracic, lumbar, and thoracolumbar counts, and sugar gliders and some semi-aquatic rodents also showed some variation; (3) longer thoracic and shorter lumbar vertebrae were typically shared traits among the examined mammals, except for flying squirrels (Pteromyini) and scaly-tailed squirrels (Anomaluridae).

CONCLUSIONS

Our study reveals that aerodynamic adaptation could potentially lead to strong selection and modification of vertebral formulae and/or proportions based on locomotive mode despite evolutionary and developmental constraints. (Folia Morphol 2018; 77, 1: 44-56).

Chemical Interaction Analysis of an Adhesive Containing 10-Methacryloyloxydecyl Dihydrogen Phosphate (10-MDP) With the Dentin in Noncarious Cervical Lesions

The purpose of this study was to evaluate the chemical bonds of a self-etch 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) adhesive to natural noncarious cervical lesions (NCCLs) and compare them with those occurring in sclerotic dentin in artificially prepared defects (APDs). Four human teeth with natural NCCLs on the buccal surface were selected. Artificial defects matching the natural lesions were prepared on the lingual surface of the same teeth serving as control. Micro-Raman (MR) spectroscopy was used to quantify mineral content in natural NCCLs and in APDs. Fourier transform infrared-photoacoustic spectroscopy (FTIR-PAS) readouts were taken before and after adhesive application to analyze the protein matrix/mineral (M:M) ratio and chemical interactions between 10-MDP adhesive and dentin. The MR and FTIR-PAS spectra collected from natural NCCLs demonstrated a larger area of the band (961 cm−1, PO4) and lower M:M ratio, respectively, characterizing a hypermineralized dentin, compared with APDs. FTIR-PAS demonstrated emergence of a peak (1179 cm−1, P=O) in spectra after adhesive treatment, demonstrating a more intense chemical interaction in natural NCCLs. The results demonstrated that chemical bonding of 10-MDP adhesive to natural NCCLs is more intense, due to the hypermineralized surface, and suggest that it is unnecessary to remove the hypermineralized layer with burs, as this may decrease the chemical bonding potential of 10-MDP.

Measurement of Coherent π^{+} Production in Low Energy Neutrino-Carbon Scattering

We report the first measurement of the flux-averaged cross section for charged current coherent π^{+} production on carbon for neutrino energies less than 1.5 GeV, and with a restriction on the final state phase space volume in the T2K near detector, ND280. Comparisons are made with predictions from the Rein-Sehgal coherent production model and the model by Alvarez-Ruso et al., the latter representing the first implementation of an instance of the new class of microscopic coherent models in a neutrino interaction Monte Carlo event generator. We observe a clear event excess above background, disagreeing with the null results reported by K2K and SciBooNE in a similar neutrino energy region. The measured flux-averaged cross sections are below those predicted by both the Rein-Sehgal and Alvarez-Ruso et al.