USP28 promotes tumorigenesis and cisplatin resistance by deubiquitinating MAST1 protein in cancer cells

Cisplatin is a chemotherapy drug that causes a plethora of DNA lesions and inhibits DNA transcription and replication, resulting in the induction of apoptosis in cancer cells. However, over time, patients develop resistance to cisplatin due to repeated treatment and thus the treatment efficacy is limited. Therefore, identifying an alternative therapeutic strategy combining cisplatin treatment along with targeting factors that drive cisplatin resistance is needed. CRISPR/Cas9 system-based genome-wide screening for the deubiquitinating enzyme (DUB) subfamily identified USP28 as a potential DUB that governs cisplatin resistance. USP28 regulates the protein level of microtubule-associated serine/threonine kinase 1 (MAST1), a common kinase whose expression is elevated in several cisplatin-resistant cancer cells. The expression level and protein turnover of MAST1 is a major factor driving cisplatin resistance in many cancer types. Here we report that the USP28 interacts and extends the half-life of MAST1 protein by its deubiquitinating activity. The expression pattern of USP28 and MAST1 showed a positive correlation across a panel of tested cancer cell lines and human clinical tissues. Additionally, CRISPR/Cas9-mediated gene knockout of USP28 in A549 and NCI-H1299 cells blocked MAST1-driven cisplatin resistance, resulting in suppressed cell proliferation, colony formation ability, migration and invasion in vitro. Finally, loss of USP28 destabilized MAST1 protein and attenuated tumor growth by sensitizing cells to cisplatin treatment in mouse xenograft model. We envision that targeting the USP28-MAST1 axis along with cisplatin treatment might be an alternative therapeutic strategy to overcome cisplatin resistance in cancer patients.

18F-ASEM PET/MRI targeting alpha7-nicotinic acetylcholine receptor can reveal skeletal muscle denervation

BACKGROUND

The increased expression of the nicotinic acetylcholine receptor (nAChR) in muscle denervation is thought to be associated with electrophysiological acetylcholine supersensitivity after nerve injury. Hence, we investigated the utility of the 18F-ASEM alpha7-nAChR targeting radiotracer as a new diagnostic method by visualizing skeletal muscle denervation in mouse models of sciatic nerve injury.

METHODS

Ten-week-old C57BL/6 male mice were utilized. The mice were anesthetized, and the left sciatic nerve was resected after splitting the gluteal muscle. One week (n = 11) and three weeks (n = 6) after the denervation, 18F-ASEM positron emission tomography/magnetic resonance imaging (PET/MRI) was acquired. Maximum standardized uptake values (SUVmax) of the tibialis anterior muscle were measured for the denervated side and the control side. Autoradiographic evaluation was performed to measure the mean counts of the denervated and control tibialis anterior muscles at one week. In addition, immunohistochemistry was used to identify alpha7-nAChR-positive areas in denervated and control tibialis anterior muscles at one week (n = 6). Furthermore, a blocking study was conducted with methyllycaconitine (MLA, n = 5).

RESULTS

18F-ASEM PET/MRI showed significantly increased 18F-ASEM uptake in the denervated tibialis anterior muscle relative to the control side one week and three weeks post-denervation. SUVmax of the denervated muscles at one week and three weeks showed significantly higher uptake than the control (P = 0.0033 and 0.0277, respectively). The relative uptake by autoradiography for the denervated muscle was significantly higher than in the control, and immunohistochemistry revealed significantly greater alpha7-nAChR expression in the denervated muscle (P = 0.0277). In addition, the blocking study showed no significant 18F-ASEM uptake in the denervated side when compared to the control (P = 0.0796).

CONCLUSIONS

Our results suggest that nAChR imaging with 18F-ASEM has potential as a noninvasive diagnostic method for peripheral nervous system disorders.

E3 ubiquitin ligase APC/CCdh1 regulates SLC35F2 protein turnover and inhibits cancer progression in HeLa cells

BACKGROUND

The solute carrier family 35 F2 (SLC35F2), belongs to membrane-bound carrier proteins that control various physiological functions and are activated in several cancers. However, the molecular mechanism regulating SLC35F2 protein turnover and its implication in cancer progression remains unexplored. Therefore, screening for E3 ligases that promote SLC35F2 protein degradation is essential during cancer progression.

METHODS

The immunoprecipitation and Duolink proximity ligation assays (PLA) were used to determine the interaction between APC/CCdh1 and SLC35F2 proteins. A CRISPR/Cas9-mediated knockdown and rescue experiment were used to validate the functional significance of APC/CCdh1 on SLC35F2 protein stabilization. The ubiquitination function of APC/CCdh1 on SLC35F2 protein was validated using in vitro ubiquitination assay and half-life analysis. The role of APC/CCdh1 regulating SLC35F2-mediated tumorigenesis was confirmed by in vitro oncogenic experiments in HeLa cells.

RESULTS

Based on the E3 ligase screen and in vitro biochemical experiments, we identified that APC/CCdh1 interacts with and reduces SLC35F2 protein level. APC/CCdh1 promotes SLC35F2 ubiquitination and decreases the half-life of SLC35F2 protein. On the other hand, the CRISPR/Cas9-mediated depletion of APC/CCdh1 increased SLC35F2 protein levels. The mRNA expression analysis revealed a negative correlation between APC/CCdh1 and SLC35F2 across a panel of cancer cell lines tested. Additionally, we demonstrated that depletion in APC/CCdh1 promotes SLC35F2-mediated cell proliferation, colony formation, migration, and invasion in HeLa cells.

CONCLUSION

Our study highlights that APC/CCdh1 is a critical regulator of SLC35F2 protein turnover and depletion of APC/CCdh1 promotes SLC35F2-mediated tumorigenesis. Thus, we envision that APC/CCdh1-SLC35F2 axis might be a therapeutic target in cancer.

Injectable Human Hair Keratin-Fibrinogen Hydrogels for Engineering 3D Microenvironments to Accelerate Oral Tissue Regeneration

Traumatic injury of the oral cavity is atypical and often accompanied by uncontrolled bleeding and inflammation. Injectable hydrogels have been considered to be promising candidates for the treatment of oral injuries because of their simple formulation, minimally invasive application technique, and site-specific delivery. Fibrinogen-based hydrogels have been widely explored as effective materials for wound healing in tissue engineering due to their uniqueness. Recently, an injectable foam has taken the spotlight. However, the fibrin component of this biomaterial is relatively stiff. To address these challenges, we created keratin-conjugated fibrinogen (KRT-FIB). This study aimed to develop a novel keratin biomaterial and assess cell-biomaterial interactions. Consequently, a novel injectable KRT-FIB hydrogel was optimized through rheological measurements, and its injection performance, swelling behavior, and surface morphology were investigated. We observed an excellent cell viability, proliferation, and migration/cell-cell interaction, indicating that the novel KRT-FIB-injectable hydrogel is a promising platform for oral tissue regeneration with a high clinical applicability.

1027 Differences in Polysomnography-Based Sleep Disorders Between HIV-Infected Persons and Matched Controls

Introduction

Sleep disturbance is a prevalent problem among HIV-infected persons. The recognition of comorbid sleep disorders in patients with HIV is currently hampered by limited knowledge of sleep-related symptoms, sleep architecture, and types of sleep disorders. We aimed to compare the differences in sleep-related symptoms and polysomnography-based sleep disorders between HIV-infected persons and controls.

Methods

The study included 170 men with a Pittsburgh sleep quality index (PSQI) greater than 5, composed of 44 HIV-infected men and 126 male controls who were frequency-matched by sex, age (-/+ 3.0 years) and BMI (-/+ 3.0 kg/m2). For all participants an overnight sleep study using a Somte V1 monitor was conducted. Differences in sleep-related symptoms and sleep disorders between HIV-infected patients and controls were examined using t-tests or Chi-square tests.

Results

HIV-infected persons with sleep disturbances more often had psychological disturbances (72.7% vs. 40.5%, p<0.001) and suspected rapid eye movement (REM) behavior disorder (RBD) (25.0% vs. 4.8%, p<0.01) than that of controls. The sleep-disordered breathing (SDB) in HIV-infected persons was less common than that in controls (56.8% vs. 87.3%, p<0.001). The mean percentage of REM sleep among HIV-infected patients was higher than that among the controls (20.6% vs. 16.6%, p<0.001). Enuresis was more common in HIV-infected persons than controls (40.9% vs. 22.2%, p=0.02).

Conclusion

Psychological disturbances and SDB can be the possible explanations of sleep disturbances in HIV-infected persons, in which suspected RBD is notable. Further studies are warranted to examine underlying factors of suspected RBD among HIV-infected persons with sleep disturbances.

Support

This work was supported by the Ministry of Science and Technology, Executive Yuan of Taiwan [MOST 105-3011-E-006-002], and National Cheng Kung University Hospital [NCKUH-10702022]

Environmental sustainability assessment from planetary boundaries perspective - A case study of an organic sheep farm in Finland

Food production processes may have both positive and negative environmental sustainability impacts. This makes decision-making challenging in the transition towards more sustainable food production systems. In this paper, a new method for presenting environmental impacts in the context of planetary boundaries is demonstrated. This will help food and agricultural producers compare the magnitudes of various environmental impacts. The environmental sustainability impacts of an organic sheep farm in the boreal climate zone in Finland are studied herein first using a life cycle assessment method. The results are then normalized and presented in a planetary boundary framework to ascertain the extent of different environmental impacts. The results show that in the planetary boundary context, there are positive impacts of sheep grazing on biosphere integrity (genetic diversity) and biogeochemical flows and negative impacts on climate change, land use or freshwater use. Magnitudes of the impacts greatly dependent on the assumptions made especially regarding biosphere integrity impacts. In the future, it is crucial that decision-making be based on the evaluation of various environmental impacts and that the focus be more on complex sustainability thinking, rather than on one single environmental impact. This research demonstrates that results from a life cycle assessment can be modified and presented in a planetary boundaries context. A planetary boundary framework approach similar to that proposed herein could be further used to identify different environmental sustainability perspectives and to help one better recognize the multifunctional aspects of the ecosystem processes.

P1-11-10: Quality of Breast Cancer Care in a Boston Area Patient Navigator Program

Background: Elimination of disparities is critically important for lessening the burden of cancer. Patient navigator programs (PNPs) assist with all aspects of care, including access, cancer prevention, screening, post-diagnosis care, and survivorship care. Little is known about the effect of PNPs on patient care and outcomes following the diagnosis of breast cancer (BC). We examined quality measures (QMs) of breast cancer care among women participating in the Massachusetts General Hospital Avon Breast Care Patient Navigator Program (MABCP), which provides patient navigation services to disadvantaged minority communities in the greater Boston area.

Methods: Women diagnosed with BC who participated in the MABCP from 2001 to 2011 were followed to determine the proportion whose care was concordant with American Society of Clinical Oncology/National Comprehensive Cancer Network (ASCO/NCCN) QMs. QMs included 1) hormonal therapy (HT) within 1 year of diagnosis for HR+ tumors > 1 cm; 2)chemotherapy within 120 days of diagnosis of HR- >1cm tumors for women <70 years; and 3) post-lumpectomy radiation therapy (XRT). Descriptive statistics were used to report characteristics of MABCP patients.

Results: Of the 186 MABCP patients diagnosed with BC, some treatment data was available on 158 (85%) and race/stage information was available on 149 (80%) [Table 1]. Among the MABCP patients, concordant care was received by 70/74 (95%) for the HT QM, 15/17 (88%) for the chemotherapy QM, and 65/71 (92%) for the XRT QM. In comparison, available benchmark concordance rates of BC patients treated at 8 NCCN centers from 2003–6 are: 340/382 (89%) for the HT QM, 156/179 (87%) for the chemotherapy QM, and 141/148 (95%) for the XRT QM.

Conclusions: Overall, breast cancer care in the MABCP PNP is concordant with published ASCO/NCCN quality measures. At present, the sample is insufficient to compare concordance rates with NCCN patients but preliminarily, it appears that the quality of care is comparable. Future research should include prospective analyses of quality metrics to assess the process and outcomes of patient navigation in diverse settings, compared with control populations.

The ATP/DNA ratio is a better indicator of islet cell viability than the ADP/ATP ratio

Real-time, accurate assessment of islet viability is critical for avoiding transplantation of nontherapeutic preparations. Measurements of the intracellular ADP/ATP ratio have been recently proposed as useful prospective estimates of islet cell viability and potency. However, dead cells may be rapidly depleted of both ATP and ADP, which would render the ratio incapable of accounting for dead cells. Since the DNA of dead cells is expected to remain stable over prolonged periods of time (days), we hypothesized that use of the ATP/DNA ratio would take into account dead cells and may be a better indicator of islet cell viability than the ADP/ATP ratio. We tested this hypothesis using mixtures of healthy and lethally heat-treated (HT) rat insulinoma cells and human islets. Measurements of ATP/DNA and ADP/ATP from the known mixtures of healthy and HT cells and islets were used to evaluate how well these parameters correlated with viability. The results indicated that ATP and ADP were rapidly (within 1 hour) depleted in HT cells. The fraction of HT cells in a mixture correlated linearly with the ATP/DNA ratio, whereas the ADP/ADP ratio was highly scattered, remaining effectively unchanged. Despite similar limitations in both ADP/ADP and ATP/DNA ratios, in that ATP levels may fluctuate significantly and reversibly with metabolic stress, the results indicated that ATP/DNA was a better measure of islet viability than the ADP/ATP ratio.

Potent in vivo antimalarial activity of 3,15-di-O-acetylbruceolide against Plasmodium berghei infection in mice

The antimalarial activity of the O-acylated bruceolide derivative, 3,15-di-O-acetylbruceolide, was evaluated against Plasmodium berghei in vivo. The concentration of 3,15-di-O-acetylbruceolide required for 50% suppression (ED50) of P. berghei in mice was 0.46 +/- 0.06 mg/kg/day, whereas bruceolide was only half as effective as 3,15-di-O-acetylbruceolide. Two antimalarial drugs used clinically, chloroquine and artemisinin, demonstrated only low activity corresponding to 1/4 and 1/12 of the ED50 value of 3,15-di-O-acetylbruceolide, respectively. These results may be helpful in the design of better chemotherapeutic bruceolides against falciparum malaria.