CD147 promotes melanoma progression through hypoxia-induced MMP2 activation

Hypoxia enhances MMP2 expression and the invasion and metastatic potential of melanoma cells. CD147 has been shown to induce MMP2 in multiple cancers. To investigate the role of CD147 in hypoxiainduced MMP2 activation, we performed immunohistochemistry (IHC) staining in 206 normal and melanoma tissue samples, and analyzed the correlation between HIF1α and CD147. ChIP (chromosome Immunoprecipitation) in melanoma cell lines supports that HIF1α directly binds to CD147 promoter. Moreover, we made a series of deletion mutants of CD147 promoter, and identified a conserved HIF1α binding site. Point mutation in this site significantly decreased CD147 response to hypoxia. Importantly, knocking down CD147 attenuates MMP2 response to hypoxia in melanoma cell lines. MMP2 could not be efficiently activated by hypoxia in CD147 depletion cells. ELISA data showed that MMP2 secretion was reduced in CD147 depletion cells than control under hypoxia condition. To verify the data from cell culture model, we performed in vivo mouse xenograft experiment. IHC staining showed reduced MMP2 level in CD147 depleted xenografts compared to the control group, with the HIF1α level being comparable. Our study demonstrates a novel pathway mediated by CD147 to promote the MMP2 activation induced by hypoxia, and helps to understand the interplay between hypoxia and melanoma progression.

Can Mathematical Models Predict the Outcomes of Prostate Cancer Patients Undergoing Intermittent Androgen Deprivation Therapy?

Androgen deprivation therapy is a common treatment for advanced or metastatic prostate cancer. Like the normal prostate, most tumors depend on androgens for proliferation and survival but often develop treatment resistance. Hormonal treatment causes many undesirable side effects which significantly decrease the quality of life for patients. Intermittently applying androgen deprivation in cycles reduces the total duration with these negative effects and may reduce selective pressure for resistance. We extend an existing model which used measurements of patient testosterone levels to accurately fit measured serum prostate specific antigen (PSA) levels. We test the model's predictive accuracy, using only a subset of the data to find parameter values. The results are compared with those of an existing piecewise linear model which does not use testosterone as an input. Since actual treatment protocol is to re-apply therapy when PSA levels recover beyond some threshold value, we develop a second method for predicting the PSA levels. Based on a small set of data from seven patients, our results showed that the piecewise linear model produced slightly more accurate results while the two predictive methods are comparable. This suggests that a simpler model may be more beneficial for a predictive use compared to a more biologically insightful model, although further research is needed in this field prior to implementing mathematical models as a predictive method in a clinical setting. Nevertheless, both models are an important step in this direction.

Quiescence as an explanation of Gompertzian tumor growth revisited

Gompertz's empirical equation remains the most popular one in describing cancer cell population growth in a wide spectrum of bio-medical situations due to its good fit to data and simplicity. Many efforts were documented in the literature aimed at understanding the mechanisms that may support Gompertz's elegant model equation. One of the most convincing efforts was carried out by Gyllenberg and Webb. They divide the cancer cell population into the proliferative cells and the quiescent cells. In their two dimensional model, the dead cells are assumed to be removed from the tumor instantly. In this paper, we modify their model by keeping track of the dead cells remaining in the tumor. We perform mathematical and computational studies on this three dimensional model and compare the model dynamics to that of the model of Gyllenberg and Webb. Our mathematical findings suggest that if an avascular tumor grows according to our three-compartment model, then as the death rate of quiescent cells decreases to zero, the percentage of proliferative cells also approaches to zero. Moreover, a slow dying quiescent population will increase the size of the tumor. On the other hand, while the tumor size does not depend on the dead cell removal rate, its early and intermediate growth stages are very sensitive to it.

Multipoint targeting of the PI3K/mTOR pathway in mesothelioma

BACKGROUND

Mesothelioma is a notoriously chemotherapy-resistant neoplasm, as is evident in the dismal overall survival for patients with those of asbestos-associated disease. We previously demonstrated co-activation of multiple receptor tyrosine kinases (RTKs), including epidermal growth factor receptor (EGFR), MET, and AXL in mesothelioma cell lines, suggesting that these kinases could serve as novel therapeutic targets. Although clinical trials have not shown activity for EGFR inhibitors in mesothelioma, concurrent inhibition of various activated RTKs has pro-apoptotic and anti-proliferative effects in mesothelioma cell lines. Thus, we hypothesised that a coordinated network of multi-RTK activation contributes to mesothelioma tumorigenesis.

METHODS

Activation of PI3K/AKT/mTOR, Raf/MAPK, and co-activation of RTKs were evaluated in mesotheliomas. Effects of RTK and downstream inhibitors/shRNAs were assessed by measuring mesothelioma cell viability/growth, apoptosis, activation of signalling intermediates, expression of cell-cycle checkpoints, and cell-cycle alterations.

RESULTS

We demonstrate activation of the PI3K/AKT/p70S6K and RAF/MEK/MAPK pathways in mesothelioma, but not in non-neoplastic mesothelial cells. The AKT activation, but not MAPK activation, was dependent on coordinated activation of RTKs EGFR, MET, and AXL. In addition, PI3K/AKT/mTOR pathway inhibition recapitulated the anti-proliferative effects of concurrent inhibition of EGFR, MET, and AXL. Dual targeting of PI3K/mTOR by BEZ235 or a combination of RAD001 and AKT knockdown had a greater effect on mesothelioma proliferation and viability than inhibition of individual activated RTKs or downstream signalling intermediates. Inhibition of PI3K/AKT was also associated with MDM2-p53 cell-cycle regulation.

CONCLUSIONS

These findings show that PI3K/AKT/mTOR is a crucial survival pathway downstream of multiple activated RTKs in mesothelioma, underscoring that PI3K/mTOR is a compelling target for therapeutic intervention.

Resonance tracking and vibration stablilization for high power ultrasonic transducers

Resonant frequency shift and electrical impedance variation are common phenomena in the application of high power ultrasonic transducers, e.g. in focused ultrasound surgery and in cutting. They result in low power efficiency and unstable vibration amplitude. To solve this problem, a driving and measurement system has been developed to track the resonance of high power transducers and to stabilise their vibration velocity. This has the ability to monitor the operating and performance parameters of the ultrasonic transducers in real time. The configuration of the system, with its control algorithm implemented in LabVIEW (National Instruments, Newbury, UK), ensures flexibility to suit different transducers and load conditions. In addition, with different programs, it can be utilised as a high power impedance analyser or an instantaneous electrical power measurement system for frequencies in the MHz range. The effectiveness of this system has been demonstrated in detailed studies. With it, high transducer performance at high power can be achieved and monitored in real time.

Celastrol protects kidney against ischemia-reperfusion-induced injury in rats

BACKGROUND

Ischemia-reperfusion (IR) causes various damages in renal tissues, which is exacerbated by hypoxia-induced excessive inflammation and deteriorates the prognosis of patients after kidney surgery. Celastrol is a potent inflammation inhibitor that has little toxicity. In this report, we investigated whether celastrol protects against IR-induced renal injury in rats.

MATERIALS AND METHODS

Renal IR injury was induced by occlusion of the bilateral renal pedicles for 45 min followed by reperfusion for 6 h. Celastrol or vehicle solution was intraperitoneally injected 30 min before renal ischemia, respectively. Renal histology, function, and pro-inflammatory cytokines and mediators were assessed. The effect of celastrol on nuclear translocation of nuclear factor kappa B (NF-κB) was also measured.

RESULTS

Celastrol significantly suppressed elevation of the renal function markers and the lipid peroxidation level, alleviated renal tubular damage, and decreased the levels of tumor necrosis factor-α, interleukin-1β, and monocyte chemotactic protein-1 (MCP-1) messenger RNA in kidney caused by IR. Moreover, celastrol prevented IR-induced expression of pro-inflammatory mediators, which was associated with suppression of nuclear translocation of NF-κB subunit p65.

CONCLUSIONS

Celastrol ameliorated the acute kidney injury caused by IR, which was associated with inhibiting local NF-κB activation and inflammation. Our findings suggest that celastrol could be useful for preventing IR-induced renal injury.

Switching CdSe quantum dot luminescence with a-Si:H

Dynamical control of the luminescence of quantum dots is highly important for technology in the field of telecommunication, displays, and photovoltaics. In this work we use an a-Si:H solar cell structure in which CdSe quantum dots are sandwiched. By applying a positive potential over the device, charge carriers generated in the quantum dots are transported to the a-Si:H layer and transformed into electrical energy, changing the luminescence intensity with a switching time lower than 60 ms. This is a promising new step towards using quantum dots in optical switching devices.

Expression and significance of 90K/Mac-2BP in prostate cancer

The aim of this study was to detect the differences in 90K/Mac-2BP expression in prostate cancer, benign prostatic hyperplasia and normal prostate tissues, as well as to study the significance of 90K/Mac-2BP in the early diagnosis and prognosis of prostate cancer. Comparative proteomic technologies were used in the present study. Total protein from 10 cases of prostate cancer, benign prostatic hyperplasia and normal prostate tissue was extracted and separated by two-dimensional electrophoresis (2-DE). Proteins expressed differentially by more than 2-fold were selected for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MS) and biological information analysis. The 2-DE patterns of the proteins from the normal prostate, benign prostatic hyperplasia and prostate cancer tissues were successfully identified. The average numbers of protein spots were 3,066, 3,289 and 2,986, respectively. There were 31 spots with a difference of more than 2-fold. A total of 18 proteins were identified by MS and database searches. Of these 18 proteins, the most significant differential expression was that of 90K/Mac-2BP. Functional analysis demonstrated that 90K/Mac-2BP (Mac-2 binding protein) overexpression is correlated with the occurrence, proliferation, differentiation and metastasis of cancer cells. The proteomic approach used in the present study was effective and is feasible for identifying differentially expressed proteins in prostate cancer, benign prostatic hyperplasia and normal prostate tissues. 90K/Mac-2BP may be important for the early diagnosis and prognosis of prostate cancer and may also be associated with the molecular mechanisms of prostate cancer development.