Genome-wide CRISPR/Cas9 knockout screening to mitigate cell growth inhibition induced by histone deacetylase inhibitors in recombinant CHO cells

Histone deacetylase inhibitors (iHDACs) have been extensively studied as enhancers of therapeutic protein production in recombinant Chinese hamster ovary (CHO) (rCHO) cell cultures. However, the addition of iHDACs reduces the viable cell concentration (VCC) in rCHO cell cultures, thereby reducing their potential to enhance therapeutic protein production. To mitigate the negative effects of iHDACs on VCC, screening using a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-based single-gene knockout (KO) library in rCHO cells was performed in the presence of CI994, a member of iHDACs, and 10 potential KO genes that enhanced the VCC of CI994-treated rCHO cells were identified. Among these, Bcor was validated as a promising KO target that improved VCC without negatively affecting the specific productivity in the presence of CI994. Bcor KO increased the VCC and therapeutic protein concentrations in both batch and fed-batch cultures in the presence of CI994. Taken together, these findings highlight the potential of the whole-genome CRISPR/Cas9-based single-gene KO cell library to identify KO target genes for the development of iHDAC-resistant rCHO cells for enhanced therapeutic protein production.

Mitigating transcriptional bottleneck using a constitutively active transcription factor, VP16-CREB, in mammalian cells

High-level expression of recombinant proteins in mammalian cells has long been an area of interest. Inefficient transcription machinery is often an obstacle in achieving high-level expression of recombinant proteins in mammalian cells. Synthetic promoters have been developed to improve the transcription efficiency, but have achieved limited success due to the limited availability of transcription factors (TFs). Here, we present a TF-engineering approach to mitigate the transcriptional bottlenecks of recombinant proteins. This includes: (i) identification of cAMP response element binding protein (CREB) as a candidate TF by searching for TFs enriched in the cytomegalovirus (CMV) promoter-driven high-producing recombinant Chinese hamster ovary (rCHO) cell lines via transcriptome analysis, (ii) confirmation of transcriptional limitation of active CREB in rCHO cell lines, and (iii) direct activation of the transgene promoter by expressing constitutively active CREB at non-cytotoxic levels in rCHO cell lines. With the expression of constitutively active VP16-CREB, the production of therapeutic proteins, such as monoclonal antibody and etanercept, in CMV promoter-driven rCHO cell lines was increased up to 3.9-fold. VP16-CREB was also used successfully with synthetic promoters containing cAMP response elements. Taken together, this strategy to introduce constitutively active TFs into cells is a useful means of overcoming the transcriptional limitations in recombinant mammalian cells.

Small molecule epigenetic modulators for enhancing recombinant antibody production in CHO cell cultures

Small molecule epigenetic modulators that modify epigenetic states in cells are useful tools for regulating gene expression by inducing chromatin remodeling. To identify small molecule epigenetic modulators that enhance recombinant protein expression in CHO cells, we examined eight histone deacetylase inhibitors (iHDACs) and six DNA methyltransferase inhibitors as chemical additives in recombinant CHO (rCHO) cell cultures. Among these, a benzamide-based iHDAC, CI994, was the most effective in increasing monoclonal antibody (mAb) production. Despite suppressing cell growth, the addition of CI994 to mAb-expressing GSR cell cultures at 10 μM resulted in a 2.3-fold increase in maximum mAb concentration due to a 3.0-fold increase in specific mAb productivity (q _mAb ). CI994 increased mAb mRNA levels and histone H3 acetylation in GSR cells, and ChIP-qPCR analysis revealed that CI994 significantly increased the histone H3 acetylation level at the CMV promoter driving mAb gene expression, indicating that chromatin remodeling in the promoter region results in enhanced mAb gene transcription and q _mAb . Similar beneficial effects of CI994 on mAb production were observed in mAb-expressing CS13-1.00 cells. Collectively, our findings indicate that CI994 increases mAb production in rCHO cell cultures by chromatin remodeling resulting from acetylation of histones in the mAb gene promoter. This article is protected by copyright. All rights reserved.

Development and validation of a staging system for gastric adenocarcinoma after neoadjuvant chemotherapy and gastrectomy with D2 lymphadenectomy

BACKGROUND

Neoadjuvant chemotherapy followed by gastrectomy with D2 lymphadenectomy is commonly used for patients with locally advanced gastric adenocarcinoma. The eighth AJCC ypTNM staging system was validated based on patients undergoing more limited lymphadenectomy (less than D2). The aim of this study was to develop a system for accurate staging of patients with locally advanced gastric adenocarcinoma who receive neoadjuvant chemotherapy followed by gastrectomy with D2 lymphadenectomy.

METHODS

A modified system of ypTNM was developed, based on overall survival (OS) of patients receiving neoadjuvant chemotherapy followed by gastrectomy with D2 lymphadenectomy at Memorial Sloan Kettering Cancer Center, and validated using data from an international cohort of patients who had similar treatment.

RESULTS

Of 325 patients in the derivation cohort, 33 (10·2 per cent) had ypT0 N0/+ tumours, which are not classifiable under the AJCC system. The 5-year OS rate for modified ypTNM stages I, II, IIIA and IIIB was 89, 71, 42·3 and 10 per cent respectively, compared with 82, 65·2 and 24·1 for AJCC stages I, II and III respectively. The concordance index (0·730 versus 0·709), estimated area under the curve (0·765 versus 0·740) and time-dependent receiver operating characteristic (ROC) curve throughout the observation period were all superior for modified ypTNM staging. For the validation cohort of 186 patients, the modified system was again better at separating patients into prognostic groups for OS.

CONCLUSION

The modified ypTNM staging system improves the accuracy of OS prediction for patients treated with neoadjuvant chemotherapy followed by gastrectomy with D2 lymphadenectomy.

Engineering a platform for nerve regeneration with direct application to nerve repair technology

The development of effective treatment options for repair of peripheral nerves is complicated by lack of knowledge concerning the interactions between cells and implants. A promising device, the multichannel scaffold, incorporates microporous channels, aligning glia and directing axonal growth across a nerve gap. To enhance clinical outcomes of nerve repair, a platform, representative of current implant technology, was engineered which 1) recapitulated key device features (porosity and linearity) and 2) demonstrated remyelination of adult neurons. The in vitro platform began with the study of Schwann cells on porous polycaprolactone (PCL) and poly(lactide co-glycolide) (PLGA) substrates. Surface roughness determined glial cell attachment, and an additional layer of topography, 40 μm linear features, aligned Schwann cells and axons. In addition, direct co-culture of sensory neurons with Schwann cells significantly increased neurite outgrowth, compared to neurons cultured alone (naive or pre-conditioned). In contrast to the control substrate (glass), on porous PCL substrates, Schwann cells differentiated into a mature myelinating phenotype, expressing Oct-6, MPZ and MBP. The direct applicability of this platform to nerve implants, including its response to physiological cues, allows for optimization of cell-material interactions, close observation of the regeneration process, and the study of therapeutics, necessary to advance peripheral nerve repair technology.

Tuberculosis infection via the emergency department among inpatients in South Korea: a propensity score matched analysis of the National Inpatient Sample

BACKGROUND

Emergency departments (EDs) carry a high risk of infectious disease transmission and have also been implicated in tuberculosis (TB) outbreaks.

AIM

To determine if patients who visit EDs have an increased risk of TB infection. Using South Korean inpatient sample data (2012), the risk of TB occurrence during 90 days after hospitalization for patients admitted via EDs was compared with that for patients admitted via outpatient clinics.

METHODS

The data of the 2012 Health Insurance Review and Assessment Service - National Inpatient Sample were used. TB diagnosis was based on International Classification of Diseases Version 10 [all TB (A15-A19), pulmonary TB (A15-A16) and extrapulmonary TB (A17-A18)].

FINDINGS

After propensity score matching using the demographic and clinical characteristics of the patients, 191,997 patients (64,017 patients admitted via EDs and 127,908 patients admitted via outpatient clinics) were included in this study. There was no significant difference in baseline patient characteristics between the two groups. The percentage of patients with TB admitted via EDs was higher than that of patients admitted via outpatient clinics. The likelihood of active TB occurrence was 30% higher for all TB [hazard ratio (HR) 1.30; 95% confidence interval (CI) 1.12-1.52] and pulmonary TB (HR 1.30; 95% CI 1.10-1.53) in patients admitted via EDs compared with patients admitted via outpatient clinics; this difference was significant. However, no difference in the occurrence of extrapulmonary TB was observed between the two groups.

CONCLUSIONS

The likelihood of TB infection was greater in patients admitted via EDs than in patients admitted via outpatient clinics.

Abstract P4-02-11: Accuracy of breast magnetic resonance imaging has limited value to reduce the margin-positive rate: A study in relation to the molecular subtypes

Background: Newly released guideline standardizing a negative margin after breast-conservative surgery (BCS) as “no ink on tumor” by SSO-ASTRO stressed the importance of estimation tumor extent with comprehensive breast imaging studies. To evaluate clinical value of breast magnetic resonance imaging (MRI) in patients with BCS, we compared the degree of correlation between MRI-pathology and ultrasonography (US)-pathology according to subtypes. In addition, we investigated the margin-positive rates and secondary operation rates for margin clearance.

Methods: We identified patients with invasive breast cancer who had preoperative breast MRI and ultrasound between 2011 and 2016. We excluded patients having large tumor more than 5cm or multiple tumors or undergoing mastectomy. Patients were classified into 4 subtypes based on the immunohistochemistry; luminal A, luminal B/HER2, HER2, triple-negative breast cancer (TNBC). Lin's concordance correlation coefficient was used to measure the agreement between the MRI or US and tumor extent. Tumor extent was defined as pathologic tumor size including in situ carcinoma. Margin-positivity was assessed based on intraoperative frozen examination.

Results: A total 516 patients with single tumor undergoing BCS were included. Means of tumor size were 1.99 ± 0.91 cm by pathologic examination, 1.91 ± 1.01 cm by MRI, and 1.76 ± 0.92 cm by US, respectively. The correlation coefficient of MRI-pathology was significantly higher than that of US-pathology (r=0.6975 vs. 0.6211, P=0.001). A superiority of MRI than US in measuring pathologic extent was only observed in TNBC (r=0.8089 vs. 0.6014, P<0.001), whereas the agreement between the MRI or US and tumor extents was low in the HER2 (MRI: 0.3509, US: 0.3165). Also, the margin-positive rate was higher in HER2 (luminal A, 11.6%; luminal B/HER2, 17.5%; HER2, 29.6%; TNBC, 17.8%; P=0.0382). In the post-hoc test, the HER2 was more likely to have positive margin compared to Luminal A (P=0.0039). There is no significant difference in secondary operation as margin clearance according to the subtypes (P>0.999).

Margin positive and re-excision rates according to the subtypes Luminal A (n=302)Luminal B (n=80)HER2 (n=27)TNBC (n=107)P valuePositive margin35 (11.6)14 (17.5)8 (29.6)19 (17.8)0.0382Re-excision14 (4.6)4 (5.0)1 (3.7)5 (4.7)>0.9999

Conclusions: Given a superiority of MRI to US in preoperative assessment, MRI-guided BCS did not reduce the margin-positive rate in TNBC. In the HER2, size correlation of MRI-pathology was very low, and the margin-positive rate was high. Collectively, our findings suggest that accuracy of MRI has limited value to reduce the margin-positive rate.

Citation Format: Bae SJ, Ahn SG, Yoon C, Cha YJ, Jeong J. Accuracy of breast magnetic resonance imaging has limited value to reduce the margin-positive rate: A study in relation to the molecular subtypes [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 P4-02-11.

Steering and control of miniaturized untethered soft magnetic grippers with haptic assistance

Untethered miniature robotics have recently shown promising results in several scenarios at the microscale, such as targeted drug delivery, microassembly, and biopsy procedures. However, the vast majority of these small-scale robots have very limited manipulation capabilities, and none of the steering systems currently available enable humans to intuitively and effectively control dexterous miniaturized robots in a remote environment. In this paper, we present an innovative micro teleoperation system with haptic assistance for the intuitive steering and control of miniaturized self-folding soft magnetic grippers in 2-D space. The soft grippers can be wirelessly positioned using weak magnetic fields and opened/closed by changing their temperature. An image-guided algorithm tracks the position of the controlled miniaturized gripper in the remote environment. A haptic interface provides the human operator with compelling haptic sensations about the interaction between the gripper and the environment, as well as enables the operator to intuitively control the target position and grasping configuration of the gripper. Finally, magnetic and thermal control systems regulate the position and grasping configuration of the gripper. The viability of the proposed approach is demonstrated through two experiments involving 26 human subjects. Providing haptic stimuli elicited statistically significant improvements in the performance of the considered navigation and micromanipulation tasks. Note to Practitioners-The ability to accurately and intuitively control the motion of miniaturized grippers in remote environments can open new exciting possibilities in the fields of minimally-invasive surgery, micromanipulation, biopsy, and drug delivery. This paper presents a micro teleoperation system with haptic assistance through which a clinician can easily control the motion and open/close capability of miniaturized wireless soft grippers. It introduces the underlying autonomous magnetic and thermal control systems, their interconnection with the master haptic interface, and an extensive evaluation in two real-world scenarios: following of a predetermined trajectory, and pick-and-place of a microscopic object.

Augmented reality in bone tumour resection: An experimental study

OBJECTIVES

We evaluated the accuracy of augmented reality (AR)-based navigation assistance through simulation of bone tumours in a pig femur model.

METHODS

We developed an AR-based navigation system for bone tumour resection, which could be used on a tablet PC. To simulate a bone tumour in the pig femur, a cortical window was made in the diaphysis and bone cement was inserted. A total of 133 pig femurs were used and tumour resection was simulated with AR-assisted resection (164 resection in 82 femurs, half by an orthropaedic oncology expert and half by an orthopaedic resident) and resection with the conventional method (82 resection in 41 femurs). In the conventional group, resection was performed after measuring the distance from the edge of the condyle to the expected resection margin with a ruler as per routine clinical practice.

RESULTS

The mean error of 164 resections in 82 femurs in the AR group was 1.71 mm (0 to 6). The mean error of 82 resections in 41 femurs in the conventional resection group was 2.64 mm (0 to 11) (p < 0.05, one-way analysis of variance). The probabilities of a surgeon obtaining a 10 mm surgical margin with a 3 mm tolerance were 90.2% in AR-assisted resections, and 70.7% in conventional resections.

CONCLUSION

We demonstrated that the accuracy of tumour resection was satisfactory with the help of the AR navigation system, with the tumour shown as a virtual template. In addition, this concept made the navigation system simple and available without additional cost or time.Cite this article: H. S. Cho, Y. K. Park, S. Gupta, C. Yoon, I. Han, H-S. Kim, H. Choi, J. Hong. Augmented reality in bone tumour resection: An experimental study. Bone Joint Res 2017;6:137-143.

Arsenic species in ecosystems affected by arsenic-rich spring water near an abandoned mine in Korea

The objectives of this study were to quantitatively estimate the distribution of arsenic with its speciation and to identify potential pathways for transformation of arsenic species from samples of water, sediments, and plants in the ecosystem affected by the Cheongog Spring, where As(V) concentration reached levels up to 0.270 mg L(-1). After flowing about 100 m downstream, the arsenic level showed a marked reduction to 0.044 mg L(-1) (about 84% removal) without noticeable changes in major water chemistry. The field study and laboratory hydroponic experiments with the dominant emergent plants along the creek (water dropwort and thunbergian smartweed) indicated that arsenic distribution, reduction, and speciation appear to be controlled by, (i) sorption onto stream sediments in exchangeable fractions, (ii) bioaccumulation by and possible release from emergent plants, and (iii) transformation of As(V) to As(III) and organic species through biological activities.

Unilateral buttock reconstruction using contralateral inferior gluteal artery perforator flap with the aid of multi-detector CT

SUMMARY

The applicability of inferior gluteal artery perforator (IGAP) flaps in breast reconstruction following breast cancer has been well described. However, the use of IGAP flaps in buttock augmentation has not been presented. We present the case of a female patient with buttock asymmetry and a deficiency of volume, who underwent buttock reconstruction based on a contralateral IGAP flap. Multidetector computed tomography (MDCT) was used to study donor and recipient areas, and allowed easy interpretation as it provided anatomical images and three-dimensional anatomy reconstructions. Based on a knowledge of individual anatomical perforating vessel distributions, safe perforator flaps can be designed. Moreover, we are convinced that buttock reconstruction using autologous tissue can be performed in a safe and reliable fashion using perforator flaps. Donor site morbidity was minimal and the muscle at the donor site was preserved. The contralateral buttock proved an excellent donor site for aesthetic unilateral buttock reconstruction and provided ample tissue in the described case.

Effect of cryoprotectants on the reconstitution of surfactant-free nanoparticles of poly(DL-lactide-co-glycolide)

Various cryoprotectants were tested to reconstitute the surfactant-free nanoparticles of poly(DL-lactide-co-glycolide) (PLGA). When 2.0% (w/v) of sucrose, trehalose and lactose were used, nanoparticles were completely reconstituted into aqueous solution and particle size was not significantly changed. Above 1.0% (w/v) of sucrose, trehalose and lactose, nanoparticles are well reconstituted whereas it was precipitated with 1.0% (w/v) of mannitol. Drug-encapsulated surfactant-free nanoparticles were quite reconstituted when 2.0% (w/v) of sucrose, trehalose and lactose. Drug release kinetics of nanoparticles was not significantly changed by cryoprotectants.

CREB regulates hepatic gluconeogenesis through the coactivator PGC-1

When mammals fast, glucose homeostasis is achieved by triggering expression of gluconeogenic genes in response to glucagon and glucocorticoids. The pathways act synergistically to induce gluconeogenesis (glucose synthesis), although the underlying mechanism has not been determined. Here we show that mice carrying a targeted disruption of the cyclic AMP (cAMP) response element binding (CREB) protein gene, or overexpressing a dominant-negative CREB inhibitor, exhibit fasting hypoglycaemia [corrected] and reduced expression of gluconeogenic enzymes. CREB was found to induce expression of the gluconeogenic programme through the nuclear receptor coactivator PGC-1, which is shown here to be a direct target for CREB regulation in vivo. Overexpression of PGC-1 in CREB-deficient mice restored glucose homeostasis and rescued expression of gluconeogenic genes. In transient assays, PGC-1 potentiated glucocorticoid induction of the gene for phosphoenolpyruvate carboxykinase (PEPCK), the rate-limiting enzyme in gluconeogenesis. PGC-1 promotes cooperativity between cyclic AMP and glucocorticoid signalling pathways during hepatic gluconeogenesis. Fasting hyperglycaemia is strongly correlated with type II diabetes, so our results suggest that the activation of PGC-1 by CREB in liver contributes importantly to the pathogenesis of this disease.

Minimization of MC1R selectivity by modification of the core structure of alpha-MSH-ND

BACKGROUND

Melanocortin, through its distinct receptor subtypes, has many different effects. Receptor-selective ligands are required to reduce the undesirable effects of melanocortin. To investigate which conformation is preferable to a given melanocortin receptor subtype, a structural and functional analysis of the ligand-receptor interactions was made by studying the biological activity, the nuclear magnetic resonance structures, and the patterns of the ligand-receptor interaction for each receptor subtype by homology modeling analysis.

RESULTS

Among the several analogues examined, [Gln(6)]alpha-melanocyte-stimulating hormone (MSH)-ND was found to have 10000 times less biological activity than alpha-MSH-ND for the MC1R, whereas, the potencies of both oligopeptides were comparable in both the melanocortin-3 receptor (MC3R) and MC4R. [Gln(6)]alpha-MSH-ND exhibited a type I' beta-turn that was similar to the type I beta-turn structure of alpha-MSH-ND. However, a remarkable structural difference was observed with respect to the side chain orientations of the sixth and seventh residues of [Gln(6)]alpha-MSH-ND, which were found to be mirror images of alpha-MSH-ND. By homology modeling analysis, the His(6) of alpha-MSH-ND was found to interact with the TM2 regions of all three receptors (Glu(94) of MC1R, Glu(94) of MC3R, and Glu(100) of MC4R), but [Gln(6)]alpha-MSH-ND did not. The phenyl ring of the D-Phe(7) residue of [Gln(6)]alpha-MSH-ND revealed an interaction with the TM3 regions of both the MC3R and MC4R (Ser(122) of MC3R or Ser(127) of MC4R). However, in the MC1R, these serine residues corresponded to Val(122), which contains two methyl groups that induce steric hindrance with D-Phe(7) of [Gln(6)]alpha-MSH-ND. This is a possible explanation for the biological activity of [Gln(6)]alpha-MSH-ND for the MC1R being significantly lower than that for either the MC3R or MC4R.

CONCLUSIONS

Minimization of the MC1R selectivity whilst preserving its comparable potency for both the MC3R and MC4R could be achieved by modifying the D-Phe(7) orientation of alpha-MSH-ND, while maintaining the 'type I beta-turn'-like structure.