Responses of cancer cells with wild-type or tyrosine kinase domain-mutated epidermal growth factor receptor (EGFR) to EGFR-targeted therapy are linked to downregulation of hypoxia-inducible factor-1α

<p>Abstract</p> <p>Background</p> <p>Searching for novel molecular markers that dependably predict or indicate responses of human cancer cells to epidermal growth factor receptor (EGFR)-targeted therapy is strongly warranted. The purpose of the current study was to evaluate hypoxia-inducible factor-1α (HIF-1α) as a novel response marker compared with previously explored markers following treatment with an EGFR-blocking monoclonal antibody (cetuximab) and a small-molecule EGFR tyrosine kinase inhibitor (gefitinib) in a group of cancer cell lines containing wild-type or tyrosine kinase domain-mutated EGFR.</p> <p>Results</p> <p>We found that, compared with previously studied response markers, including EGFR <it>per se </it>and three EGFR downstream signal molecules (ERK, Akt, and STAT3), which showed variable post-treatment changes in levels of phosphorylation and no consistent link of the changes to therapeutic responses, HIF-1α showed a selective decrease in protein levels only in responsive cell lines. To demonstrate a critical role of HIF-1α downregulation by EGFR-targeted treatment, we introduced a constitutively expressed HIF-1α mutant (HIF-1α/ΔODD) that is resistant to cetuximab-induced downregulation in a cetuximab-responsive cell line (A431); we found that the HIF-1α/ΔODD-transfected cells remained sensitive to cetuximab-induced inhibition of Akt and ERK phosphorylation but were remarkably less responsive to cetuximab-induced growth inhibition compared with corresponding control cells.</p> <p>Conclusion</p> <p>Our data indicates that downregulation of HIF-1α is associated with positive therapeutic responses of cancer cells to EGFR-targeted therapy and suggest further investigation using HIF-1α as an indicator of tumor response to EGFR-targeted therapy in preclinical studies and in the clinical setting.</p

In-Hospital Cardiac Arrest after Emotional Stress in a Patient Hospitalized with Gastrointestinal Symptoms and Chronic Anxiety Disorder

Background: We report an acute emotional stress–induced in-hospital cardiac arrest in a patient admitted with gastrointestinal symptoms after experiencing chronic anxiety disorder. Case Presentation: The patient was admitted to the Second Xiangya Hospital, Central South University, with gastrointestinal symptoms and chronic anxiety disorder, and experienced cardiac arrest during hospitalization after acute emotional stress. Malignant ventricular tachycardia and cardiogenic shock were evidenced in this patient after the acute emotional stress. Severe and extensive coronary spasm was confirmed by emergency coronary angiography, and coronary spasm was relieved by intracoronary injection of nitroglycerin. The patient recovered from myocardial infarction with nonobstructive coronary arteries. However, the patient developed acute kidney dysfunction and severe pulmonary infection and eventually died of respiratory circulatory failure on the ninth day after the successful rescue. Conclusions: Acute emotional stress on top of chronic anxiety disorder in patients hospitalized for noncardiovascular reasons might lead to the development of life-threatening cardiovascular diseases, including coronary artery spasm and myocardial infarction with nonobstructive coronary arteries. Psychological management is of importance to improve the outcome of these patients. </p

Clinical Significance of Angiographically Detectable Neovascularity in Patients with Cardiac Myxoma

Background: Myxomas are the most common primary cardiac tumors. Angiographically detectable neovascularity (ADN) of myxoma is increasingly being reported as a result of the use of coronary angiography (CAG) to detect coronary artery disease. However, the clinical significance of these findings is not fully understood. Methods: We enrolled 59 patients with cardiac myxoma who also underwent CAG between January 2013 and October 2018. Patients were followed up for a mean of 28.9 months (range 1–69 months). The clinical features, echocardiography measurements, pathological examination findings, CAG results, and outcomes during follow-up were compared between patients with ADN and patients without ADN. Results: ADN was found in 25 patients (42.4%). The arteries feeding the ADN included the right coronary artery ( n=15), the left circumflex coronary artery ( n=7), and both arteries ( n=3). The patients with ADN had a higher proportion of eosinophils (3.2% vs. 2.2%, P=0.03) and higher low-density lipoprotein cholesterol level (2.7 mmol/L vs. 2.2 mmol/L, P=0.02). Myxoma pedicles were more likely to be located in the interatrial septum in patients with ADN (96% vs. 73.5%, P=0.02). No significant correlation was observed between the groups in clinical manifestations, atrial arrhythmia, myxoma size, cardiac chamber size, left ventricular ejection fraction, and the prevalence of complication with coronary artery disease [16% in the ADN group ( n=4) vs. 20.6% in the non-ADN group ( n=7), P=0.66]. However, patients with ADN tended to have a lower incidence of major adverse cardiac and cerebrovascular events on long-term follow-up (0% vs. 14.7%, P=0.07). Conclusion: CAG-detected ADN in patients with cardiac myxoma is associated with a borderline lower rate of major adverse cardiac and cerebrovascular events. </p

1, 9-Pyrazoloanthrones Downregulate HIF-1α and Sensitize Cancer Cells to Cetuximab-Mediated Anti-EGFR Therapy

Cetuximab, a monoclonal antibody that blocks the epidermal growth factor receptor (EGFR), is currently approved for the treatment of several types of solid tumors. We previously showed that cetuximab can inhibit hypoxia-inducible factor-1 alpha (HIF-1α) protein synthesis by inhibiting the activation of EGFR downstream signaling pathways including Erk, Akt, and mTOR. 1, 9-pyrazoloanthrone (1, 9 PA) is an anthrapyrazolone compound best known as SP600125 that specifically inhibits c-jun N-terminal kinase (JNK). Here, we report 1, 9 PA can downregulate HIF-1α independently of its inhibition of JNK. This downregulatory effect was abolished when the oxygen-dependent domain (ODD) of HIF-1α (HIF-1α-ΔODD, the domain responsible for HIF-1α degradation) was experimentally deleted or when the activity of HIF-1α prolyl hydroxylase (PHD) or the 26S proteasomal complex was inhibited, indicating that the 1, 9 PA downregulates HIF-1α by promoting PHD-dependent HIF-1α degradation. We found that the combination of 1, 9 PA and cetuximab worked synergistically to induce apoptosis in cancer cells in which cetuximab or 1, 9 PA alone had no or only weak apoptotic activity. This synergistic effect was substantially decreased in cancer cells transfected with HIF-1α-ΔODD, indicating that downregulation of HIF-1α was the mechanism of this synergistic effect. More importantly, 1, 9 PA can downregulate HIF-1α in cancer cells that are insensitive to cetuximab-induced inhibition of HIF-1α expression due to overexpression of oncogenic Ras (RasG12V). Our findings suggest that 1, 9 PA is a lead compound of a novel class of drugs that may be used to enhance the response of cancer cells to cetuximab through a complementary effect on the downregulation of HIF-1α

Differential responses to doxorubicin-induced phosphorylation and activation of Akt in human breast cancer cells

INTRODUCTION: We have shown previously that overexpression of constitutively active Akt or activation of Akt caused by constitutively active Ras or human epidermal growth factor receptor-2 (HER2) confers on breast cancer cells resistance to chemotherapy or radiotherapy. As an expanded study we here report differential responses in terms of phosphorylation and activation of Akt as a result of treatment with doxorubicin in a panel of breast cancer cell lines. METHODS: The levels of Akt phosphorylation and activity were measured by Western blot analysis with an anti-Ser473-phosphorylated Akt antibody and by in vitro Akt kinase assay using glycogen synthase kinase-3 as a substrate. RESULTS: Within 24 hours after exposure to doxorubicin, MCF7, MDA468 and T47D cells showed a drug-dose-dependent increase in the levels of phosphorylated Akt; in contrast, SKBR3 and MDA231 cells showed a decrease in the levels of phosphorylated Akt, and minimal or no changes were detected in MDA361, MDA157 and BT474 cells. The doxorubicin-induced Akt phosphorylation was correlated with increased kinase activity and was dependent on phosphoinositide 3-kinase (PI3-K). An increased baseline level of Akt was also found in MCF7 cells treated with ionizing radiation. The cellular responses to doxorubicin-induced Akt phosphorylation were potentiated after the expression of Akt upstream activators including HER2, HER3 and focal adhesion kinase. CONCLUSION: Taken together with our recent published results showing that constitutive Akt mediates resistance to chemotherapy or radiotherapy, our present data suggest that the doxorubicin-induced phosphorylation and activation of Akt might reflect a cellular defensive mechanism of cancer cells to overcome doxorubicin-induced cytotoxic effects, which further supports the current efforts of targeting PI3-K/Akt for enhancing the therapeutic responses of breast cancer cells to chemotherapy and radiotherapy

Multiple Damaged Cables Identification in Cable-Stayed Bridges Using Basis Vector Matrix Method

A new damaged cable identification method using the basis vector matrix (BVM) is proposed to identify multiple damaged cables in cable-stayed bridges. The relationships between the cable tension stiffness and the girder bending strain of the cable-stayed bridge are established using a force method. The difference between the maximum bending strains of the bridges with intact and damaged cables is used to obtain the damage index vectors (DIXVs). Then, BVM is obtained by the normalized DIXV. Finally, the damage indicator vector (DIV) is obtained by DIXV and BVM to identify the damaged cables. The damage indicator is substituted into the damage severity function to identify the corresponding damage severity. A field cable-stayed bridge is used to verify the proposed method. The three-dimensional finite element model is established using ANSYS, and the model is validated using the field measurements. The validated model is used to simulate the strain response of the bridge with different damage scenarios subject to a moving vehicle load, including one, two, three, and four damaged cables with damage severity of 10%, 20%, and 30%, respectively. The noise effect is also discussed. The results show that the BVM method has good anti-noise capability and robustness

Extraction of bridge modal parameters using a moving instrumented vehicle by SSI technique

Research on indirect bridge structural identification from the dynamic response of a moving instrumented vehicle has been very attractive in recent years. Unlike conventional bridge structural health monitoring methods that many sensors are installed directly on a bridge to obtain structural dynamic responses, the indirect bridge monitoring utilises an instrumented vehicle to capture the bridge dynamic information during its moving over the bridge. The bridge response often exhibits an inherent randomness due to the road surface roughness as well as the traffic excitation. It is suggested stochastic analysis should be performed. In this paper, the stochastic subspace identification (SSI) method is used for the structural dynamic parameter identification from the vehicle dynamic response only. To reduce the blurring effect of road surface roughness on the indirect structural model identification, two connected identical vehicles are adopted. The white noise support excitation is added to briefly simulate the traffic excitation to the bridge. Cases studies show that the improved SSI using the subtraction residual of the two connected vehicles' responses is very effective. The bridge frequencies can be successfully identified from dynamic responses of the instrumented vehicles

A steel-concrete composite beam element for structural damage identification

The composite action between the layers of steel and concrete is governed by the shear connection. Because of the complicated interconnection behavior of these composite layers, it is difficult to detect damage in the composite structures, especially, the interfacial integrity of the two layers. In this paper, anovel method has been developed for structural damage identification of composite structures based on a steel-concrete composite beam element with bonding interface. In displacement-based finite element (FE) formulation, three damage indicators have been embedded into stiffness matrix of the composite beam that are defined as a stiffness reduction in the concrete, steel and interface layers. An algorithm-based on recursive quadratic programming has been proposed to identify structural damage in the composite beam from static measurements. The analytical FE model is validated by adapting its static responses in undamaged state with those obtained from an equal experimental model as well as a FE model developed in commercial software ABAQUS. A convergence study is conducted to determine the number of the composite beam FEs. To verify the proposed method, the static responses of the FE model with different damage cases at a given loading are calculated, and the measurements are simulated by adding different levels of white noise. Then, the proposed algorithm is applied to identify damage of the composite beam. The effects of measurement noise, loading location and amplitude, measurement numbers and the sizes of FE mesh on the identified results have been investigated. The numerical results show that this method is efficient and accurate to separately identify small damage in the concrete slab, and the steel girder and bonding interface of the composite beam

Damage analysis of steel-concrete composite beams under static loads

This paper presents a study of the static behavior of steel-concrete composite beams with different types of damage. Since the behavior of a composite beam under load is governed by the shear connection, it is important to investigate the overall structural response due to different levels of damage in the interface and composite layers. A finite element (FE) model of a steel-concrete composite beam is developed based on two Euler-Bernoulli beams as the composite layers coupled with a deformable shear connection. Three different damage indices are defined for the concrete slab, the steel girder, and the distributed shear connection and then embedded into the stiffness matrix of the composite beam. This model is validated by comparing its load-displacement behavior with an equivalent FE model developed using the commercial FE software ABAQUS. The impact that the loading location has on the results is then investigated. A convergence study is also carried out in terms of the displacements and strains to determine the number of composite beam FEs. The maximum displacements and strains of composite beams with different types and levels of damage are then investigated. The numerical analysis showed that after an initial reduction when the number of FEs increase, the changes in displacement and strain at each location are very small. Moreover, the bonding slip has almost no effect on the measurements, and the changes in maximum displacement and strain from undamaged to maximum damage are almost the same

Nyquist Zone Index and Chirp Rate Estimation of LFM Signal Intercepted by Nyquist Folding Receiver Based on Random Sample Consensus and Fractional Fourier Transform

The Nyquist folding receiver (NYFR) can achieve a high-probability interception of an ultra-wideband (UWB) signal with fewer devices, while the output of the NYFR is converted into a hybrid modulated signal of the local oscillator (LO) and the received signal, which requires the matching parameter estimation methods. The linear frequency modulation (LFM) signal is a typical low probability of intercept (LPI) radar signal. In this paper, an estimation method of both the Nyquist Zone (NZ) index and the chirp rate for the LFM signal intercepted by NYFR was proposed. First, according to the time-frequency characteristics of the LFM signal, the accurate NZ and the rough chirp rate was estimated based on least squares (LS) and random sample consensus (RANSAC). Then, the information of the LO was removed from the hybrid modulated signal by the known NZ, and the precise chirp rate was obtained by using the fractional Fourier transform (FrFT). Moreover, a fast search method of FrFT optimal order was presented, which could obviously reduce the computational complexity. The simulation demonstrated that the proposed method could precisely estimate the parameters of the hybrid modulated output signal of the NYFR