CD147 interacts with NDUFS6 in regulating mitochondrial complex I activity and the mitochondrial apoptotic pathway in human malignant melanoma cells

Malignant melanoma (MM) is one of the most lethal tumors and is characterized by high invasiveness, frequent metastasis, and resistance to chemotherapy. The risk of metastatic MM is accompanied by disordered energy metabolism involving the oxidative phosphorylation (OXPHOS) process, which is largely carried out in mitochondrial complexes. Complex I is the first and largest mitochondrial enzyme complex associated with this process. CD147 is a transmembrane glycoprotein mainly expressed on the cell surface, and also appears in the cytoplasm in some tumors. We found that CD147 is often translocated to the cytoplasm in metastatic MM specimens as compared to primary MM. We also demonstrated high expression of CD147 in isolated mitochondrial fractions of A375 cells. The yeast two-hybrid (Y2H) assay identified NDUFS6 (which encodes a subunit of mitochondrial respiratory chain complex I) as a candidate that interacts with CD147 and depletion of CD147 in A375 cells significantly decreased complex I enzyme activity. We also showed that CD147 increased the viability of A375 cells exposed to berberine-induced mitochondrial damage, and protected them from apoptosis through a mitochondrial-dependent pathway. This finding was confirmed by adding exogenous Bcl-2 to A375 cell cultures. In summary, our results identify the existence of CD147 in human melanoma cell mitochondria. They indicate that CD147 appears to regulate complex I activity and apoptosis in MM by interacting with mitochondrial NDUFS6. Our findings provide new insight into the function of CD147 and identify it as a promising therapeutic target in melanoma through disruption of the energy metabolism.

Establishment, characterization, and application of pAcr-SP-NTP-EGFP transgenic mice in visualizing the oviduct-migrating ability of sperm from Prss37-null mice

Transgenic mouse model with fluorescently labeled sperm has extensive application value. It is an auxiliary tool for investigating the mechanism of fertilization, especially for visualizing the oviduct-migrating ability of sperm in vivo. Here, we produced transgenic mouse lines whose sperm were tagged with enhanced green fluorescent protein (EGFP) according to the previously described method. Polymerase chain reaction analysis of tail-tip genomic DNA identified 13 founders, of which 5 male founders produced offspring to form transgenic lines. We showed that EGFP was testis-specifically expressed, sharing similar expression pattern with endogenous acrosin. It has luminal side restricted distribution in seminiferous tubules and acrosomal aggregation in mature sperm. In addition, interstrain hybridization obtained Prss37(-/-)EGFP(tg/+) males produced sperm with impaired oviduct-migrating ability as visualized under fluorescence microscope, compared with Prss37(+/+)EGFP(tg/+) counterparts. These results indicate that a transgenic mouse model with fluorescently labeled sperm has been successfully established and it is a useful tool for evaluating the oviduct-migrating ability of sperm.

Association between the CD24 Ala57Val polymorphism and risk for multiple sclerosis and systemic lupus erythematosus: a meta-analysis

The cluster of differentiation 24 (CD24) Ala57Val polymorphism has been implicated as a risk factor for multiple sclerosis (MS) and systemic lupus erythematosus (SLE); however, genetic studies have produced controversial results. A meta-analysis was performed on this topic. We used odds ratio (OR) and 95% confidence interval (95% CI) to investigate the strength of association. Eleven studies from nine publications consisting of 2466 cases and 2650 controls were included. The results suggested that the CD24 Val/Val genotypes were associated with an increased risk of MS in all study subjects and Caucasians (OR = 2.28, 95% CI: 1.68–3.10, P_z < 0.001 and OR = 2.30, 95% CI: 1.66–3.20, P_z < 0.001, respectively). Sensitivity analysis showed that no individual study was found to be significantly biasing the pooled results. Although meta-analysis also suggested an association between the CD24 Val/Val genotypes and SLE risk in Caucasians (OR = 1.71, 95% CI: 1.31–2.24, P_z < 0.001), sensitivity analysis demonstrated that the association was not statistically significant after removing a Spanish study. In conclusion, this meta-analysis suggests that the CD24 Ala57Val polymorphism is associated with an increased risk of MS in Caucasians. However, the available evidence is not sufficient to support an association between the CD24 Ala57Val polymorphism and SLE risk.

[Corrigendum] Alterations in gene expression during sexual differentiation in androgen receptor knockout mice induced by environmental endocrine disruptors

Following the publication of this article, the authors noticed the following error: In the Abstract, the full name of DBP should be dibutyl phthalate and not D binding protein. The same error was observed on the second page of the manuscript (second line on right column), where the full name of DBP should be dibutyl phthalate and not D binding protein. [the original article was published in the International Journal of Molecular Medicine 35: 399-404, 2015 DOI: 10.3892/ijmm.2014.2015].

The Krüppel-associated box repressor domain induces reversible and irreversible regulation of endogenous mouse genes by mediating different chromatin states

The Krüppel-associated box (KRAB) domain is a transcription repression module from the largest family of transcriptional regulators encoded by higher vertebrates. We developed a drug-controllable regulation system based on an artificial KRAB-containing repressor (tTS) that targets the endogenous Hprt gene to explore the regulatory mechanism and molecular basis of KRAB-containing regulators within the context of an endogenous gene in vivo. We show that KRAB can mediate irreversible and reversible regulation of endogenous genes in mouse that is dependent on embryonic developmental stage. KRAB-induced stable DNA methylation within the KRAB binding region during the early embryonic stage, resulting in irreversible gene repression. In later stages, KRAB mainly induced de-acetylation and methylation of histone, resulting in reversible gene repression. Thus, we have characterized the KRAB-mediated regulation system within the context of an endogenous gene and multiple spatiotemporal ranges, thereby providing a basis for identifying the function of KRAB-containing regulators and aiding development of novel KRAB-based gene regulation tools in vivo.

Deficiency of BPOZ2 Decreases Liver Fibrosis After Chronic Carbon Tetrachloride Administration in Mice

Bood POZ containing gene type 2 (BPOZ2), a Broad-Complex, Tramtrack, and Bric a brac domain containing protein, is an adaptor protein for the E3 ubiquitin ligase scaffold protein CUL3. It plays an important role in acute carbon tetrachloride (CCl4)-induced liver injury and regeneration in mice. In this study, we investigated the role of BPOZ2 in the process of liver fibrosis induced by chronic CCl4 treatment. The results indicate that BPOZ2 deficiency decreases sustained activation of hepatic stellate cells, attenuates collagen αI(I) and tissue inhibitor of matrix metalloprotease 1 expression, and decreases liver fibrosis after repeated CCl4 administration. These findings suggest BPOZ2 as a new therapeutic target for the prevention and treatment of hepatic fibrosis in chronic liver disease.

Alterations in gene expression during sexual differentiation in androgen receptor knockout mice induced by environmental endocrine disruptors

In the present study, we aimed to explore the effect of environmental endocrine disruptors (EEDs) on sexual differentiation in androgen receptor (AR)-/-, AR+/- and AR+/+ male mice. By using a Cre-loxP conditional knockout strategy, we generated AR knockout mice. By mating flox-AR female mice with AR-Cre male mice, the offspring male mice which were produced were examined. Mice not subjected to any type of intervention were used as the controls. Furthermore, male mice of different genotypes were selected and further divided into subgroups as follows: the control group, bisphenol A (BPA) group and the dibutyl phthalate [corrected] (DBP) group. The expression of the Wilms tumor 1 (WT1), lutropin/choriogonadotropin receptor (LHR), 17-β-hydroxysteroid dehydrogenase type 3 (17βHSD3) and steroid-5-alpha-reductase, alpha polypeptide 2 (SRD5A2) genes was determined by RT-qPCR and western blot analysis. There was no statistically significant difference in the weight of the mice between the control group and the knockout group (P>0.05). The results revealed that, compared with the control group, in the knockout group, anogenital distance was shortened, and testicular weight and testosterone levels were decreased; estradiol levels were elevated; the differences were statistically significant (P<0.05). In the group of AR+/- male mice exposed to 100 mg/l EEDs, hypospadias was successfully induced, suggesting that EEDs are involved in the embryonic stage of sexual development in male mice. The quantitative detection of WT1, LHR, 17βHSD3 and SRD5A2 gene expression by RT-qPCR and western blot analysis indicated that these genes were significantly downregulated in the mice in the BPA group. In conclusion, exposure to EEDs induces hypospadias in heterozygous and wild-type male mice offspring during sexual differentiation, but has no effect on homozygous offspring. Therefore, EEDs play an important role during the third stage of sexual differentiation.

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.