CYP11A1 silencing suppresses HMGCR expression via cholesterol accumulation and sensitizes CRPC cell line DU-145 to atorvastatin.

Statins, which are cholesterol synthesis inhibitors, are well-known therapeutics for dyslipidemia; however, some studies have anticipated their use as anticancer agents. However, epithelial cancer cells show strong resistance to statins through an increased expression of HMG-CoA reductase (HMGCR), an inhibitory target of statins. Castration-resistant prostate cancer (CRPC) cells synthesize androgens from cholesterol on their own. We performed suppression of CYP11A1, a rate-limiting enzyme in androgen synthesis from cholesterol, using siRNA or inhibitors, to examine the effect of steroidogenesis inhibition on statin sensitivity in CRPC cells. Here, we suggested that CYP11A1 silencing sensitized the statin-resistant CRPC cell line DU-145 to atorvastatin via HMGCR downregulation by an increase in intracellular free cholesterol. We further demonstrated that CYP11A1 silencing induced epithelial-mesenchymal transition, which converted DU-145 cells into a statin-sensitive phenotype. This suggests that concomitant use of CYP11A1 inhibitors could be an effective approach for overcoming statin resistance in CRPC. Moreover, we showed that ketoconazole, a CYP11A1 inhibitor, sensitized DU-145 cells to atorvastatin, although not all the molecular events observed in CYP11A1 silencing were reproducible. Although further studies are necessary to clarify the detailed mechanisms, ketoconazole may be effective as a concomitant drug that potentiates the anticancer effect of atorvastatin.

Alterations in the omics profiles in mevalonate pathway-inhibited cancer cells.

AIMS: Statins, cholesterol-lowering drugs, are potential therapeutic agents for inhibiting cancer proliferation. However, the mechanisms that mediate the effects of statins, the homeostatic responses of tumor cells to statin therapy, and the modes underlying the antitumor effects of statins remain unclear. MAIN METHODS: To uncover the effects of statins on cancer cells in vitro, we performed transcriptome and metabolome analyses on atorvastatin-treated statin-resistant and statin-sensitive lung cancer cells. KEY FINDINGS: The results of Gene Ontology terms and pathway enrichment analyses showed that after 24 h of atorvastatin treatment, the expression of cell cycle- and DNA replication-related genes was significantly decreased in the statin-sensitive cancer cells. The results of metabolome analysis showed that the components of polyamine metabolism and purine metabolism, glycolysis, and pentose phosphate pathway were decreased in the statin-sensitive cancer cells. SIGNIFICANCE: Differences in cellular properties between statin-sensitive and statin-resistant cancer cells revealed additional candidates for therapeutic targets in statin-treated cancer cells and suggested that inhibiting these metabolic pathways could improve efficacy. In conclusion, combining statins with inhibitors of polyamine metabolism (cell proliferation and protein translation), purine metabolism (DNA synthesis), glycolytic system (energy production), and pentose phosphate pathway (antioxidant stress) might enhance the anticancer effects of statins.

Chondroitin sulfate E downregulates N-cadherin and suppresses myotube formation.

Myogenesis, the formation of muscle fibers, is affected by certain glycoproteins, including chondroitin sulfate (CS), which are involved in various cellular processes. We aimed to investigate the mechanism underlying CS-E-induced suppression of myotube formation using the myoblast cell line C2C12. Differentiated cells treated with 0.1 mg/ml CS-E for nine days showed multinucleated and rounded myotubes with myosin heavy chain positivity. No difference was found between the CS-E-treated group with rounded myotubes and CS (-) controls with elongated myotubes in the levels of phospho-cofilin, a protein involved in the dynamics of actin cytoskeleton. Interestingly, N-cadherin, which is involved in the gene expression of myoblast fusion factors (myomaker and myomixer), was significantly downregulated at both the mRNA and protein levels following CS-E treatment. These results suggest that N-cadherin downregulation is one of the mechanisms underlying the CS-E-induced suppression of myotube formation.

Atorvastatin preferentially inhibits the growth of high ZEB-expressing canine cancer cells.

The epithelial-to-mesenchymal transition (EMT) is fundamental in cancer progression and contributes to the acquisition of malignant properties. The statin class of cholesterol-lowering drugs exhibits pleiotropic anticancer effects in vitro and in vivo, and many epidemiologic studies have reported a correlation between statin use and reduced cancer mortality. We have shown previously that sensitivity to the anti-proliferative effect of statins varies among human cancer cells and statins are more effective against mesenchymal-like cells than epithelial-like ones in human cancers. There have only been few reports on the application of statins to cancer therapy in veterinary medicine, and differences in statin sensitivity among canine cancer cells have not been examined. In this study, we aimed to clarify the correlation between sensitivity to atorvastatin and epithelial/mesenchymal states in 11 canine cancer cell lines derived from mammary gland, squamous cell carcinoma, lung, and melanoma. Sensitivity to atorvastatin varied among canine cancer cells, with IC50 values ranging from 5.92 to 71.5 µM at 48 h, which were higher than the plasma concentrations clinically achieved with statin therapy. Atorvastatin preferentially attenuated the proliferation of mesenchymal-like cells. In particular, highly statin-sensitive cells were characterized by aberrant expression of the ZEB family of EMT-inducing transcription factors. However, ZEB2 silencing in highly sensitive cells did not induce resistance to atorvastatin. Taken together, these results suggest that high expression of ZEB is a characteristic of highly statin-sensitive cells and could be a molecular marker for predicting whether cancers are sensitive to statins, though ZEB itself does not confer statin sensitivity.

Estrogen modulates the skeletal muscle regeneration process and myotube morphogenesis: morphological analysis in mice with a low estrogen status.

The purpose of this study was to elucidate the functions of estrogen and two estrogen receptors (ERs; ERα and ERß) in the myoregeneration process and morphogenesis. Cardiotoxin (CTX) was injected into the tibialis anterior (TA) muscles of ovariectomized (OVX) mice to induce muscle injury, and subsequent myoregeneration was morphologically assessed. The diameter of regenerated myotubes in OVX mice was significantly smaller than that in intact mice at all time points of measurement. OVX mice also showed lower muscle recovery rates and slower speeds than did intact mice. ER protein levels showed a predominance of ERß over ERα in both intact and OVX states. The ERß level was increased significantly at 7 days after CTX injection in OVX mice and remained at a high level until 14 days. In addition, continuous administration of E2 to OVX mice in which muscle injury was induced resulted in a significantly larger diameter of regenerated myotubes than that in mice that did not receive estrogen. The results indicate that estrogen is an essential factor in the myoregeneration process since estrogen depletion delayed myoregeneration in injured muscles and administration of estrogen under the condition of a low estrogen status rescued delayed myoregeneration. The results strongly suggested that ERß may be a factor that promotes myoregeneration more than does ERα.

Concomitant attenuation of HMGCR expression and activity enhances the growth inhibitory effect of atorvastatin on TGF-ß-treated epithelial cancer cells.

Epithelial-mesenchymal transition (EMT) in primary tumor cells is a key prerequisite for metastasis initiation. Statins, cholesterol-lowering drugs, can delay metastasis formation in vivo and attenuate the growth and proliferation of tumor cells in vitro. The latter effect is stronger in tumor cells with a mesenchymal-like phenotype than in those with an epithelial one. However, the effect of statins on epithelial cancer cells treated with EMT-inducing growth factors such as transforming growth factor-ß (TGF-ß) remains unclear. Here, we examined the effect of atorvastatin on two epithelial cancer cell lines following TGF-ß treatment. Atorvastatin-induced growth inhibition was stronger in TGF-ß-treated cells than in cells not thusly treated. Moreover, treatment of cells with atorvastatin prior to TGF-ß treatment enhanced this effect, which was further potentiated by the simultaneous reduction in the expression of the statin target enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR). Dual pharmacological targeting of HMGCR can thus strongly inhibit the growth and proliferation of epithelial cancer cells treated with TGF-ß and may also improve statin therapy-mediated attenuation of metastasis formation in vivo.

Study on improvement of signal detectability considering noise characteristics in medical X-ray images.

The purpose of this study is to develop method for improvement of low-contrast signal detectability of general X-ray images used for observing overviews, included noise reduction technique and signal amplification technique, that are difficult to detect in the observing overview. The proposal method consists signal amplification part and noise reduction part. The noise reduction part first identifies and mathematizes the characteristics of the noise attributed to the X-ray imaging system before the subject is imaged. The noise information derived from mathematization is used to remove the noise representing the system noise from the subject image. After noise reduction, all the signals on the subject image with sufficiently reduced noise are amplified by multiplication with an arbitrary coefficient. The feasibility of the proposed method was indicated by three evaluations that were performed vision assessment using the image including the virtual low-contrast signals by four radiological technologists. That of the proposed method was confirmed from results of the evaluations. That of the proposed method was confirmed from results of the evaluations.

Phantom-based comparison of conventional versus phase-contrast mammography for LCD soft-copy diagnosis.

PURPOSE: Liquid crystal display (LCD) of mammograms provides soft-copy results that differ in conventional and phase contrast mammography (PCM). PCM potentially offers the highest quality of sharpness and graininess, an edge emphasis effect on the object, and the highest image resolution. However, when the image is displayed on an LCD, the resolution depends on the pixel pitch and the PCM image data must be diminished. We investigated the observed effect on spatial resolution and contrast when conventional or phase contrast mammograms are viewed on an LCD. METHODS: Using the tissue-equivalent phantom (Model 1011A), a conventional mammogram and a magnification radiography image were obtained with a PCM system. This phantom contains simulated fibers, microcalcifications, and masses. The PCM image was reduced 1/1.75 to render it consistent with life size mammography using the nearest neighbor, bilinear, and bicubic interpolation methods. The images were displayed on a five million (5M)-pixel LCD with 100 % magnification. Ten mammography technicians observed the reduction images displayed on LCDs and reported their results. RESULTS: In the detectability of the microcalcifications, there was no significant difference between conventional mammograms and reduced PCM images. Regarding fibers and masses, detectability using reduced images was higher than those of conventional images. The detectability using images reduced by the nearest-neighbor method was lower than those of images reduced by two other interpolation methods. Bilinear interpolation was affected by the smoothing effect, while CNR was increased. In addition, since the noise of PCM image was reduced by an air gap effect, high detectability of key image features was found. CONCLUSIONS: Soft-copy display of phase-contrast mammograms is feasible with LCDs, while detectability of fibers and masses was best with bilinear interpolation and use of an air gap.

[Development of automatic navigation measuring system using template-matching software in image guided neurosurgery].

An image-guided neurosurgery and neuronavigation system based on magnetic resonance imaging has been used as an indispensable tool for resection of brain tumors. Therefore, accuracy of the neuronavigation system, provided by periodic quality assurance (QA), is essential for image-guided neurosurgery. Two types of accuracy index, fiducial registration error (FRE) and target registration error (TRE), have been used to evaluate navigation accuracy. FRE shows navigation accuracy on points that have been registered. On the other hand, TRE shows navigation accuracy on points such as tumor, skin, and fiducial markers. This study shows that TRE is more reliable than FRE. However, calculation of TRE is a time-consuming, subjective task. Software for QA was developed to compute TRE. This software calculates TRE automatically by an image processing technique, such as automatic template matching. TRE was calculated by the software and compared with the results obtained by manual calculation. Using the software made it possible to achieve a reliable QA system.

Evaluation of errors influencing accuracy in image-guided neurosurgery.

Neurosurgeons sometimes find it difficult to locate tumors precisely during microsurgery, particularly tumors located in the brain parenchyma because of the absence of boundaries in this region. Image-guided neurosurgical techniques conducted with the help of neuronavigation systems have been developed and have gained importance recently. Accuracy is vital during image-guided neurosurgery. We used a phantom to evaluate the errors introduced during navigation. The three errors evaluated were skin-shift, marker-gap, and table-rotation errors. The skin-shift error occurs if the fiducial markers positioned on the scalp move when the head is fixed to a head holder with head pins. The marker-gap error occurs when the marker ball is positioned incorrectly in the marker socket. The table-rotation error occurs when the operating table is rotated for obtaining an intraoperative MR image and then returned to its original position. Our results indicated that skin shift decreased the navigation accuracy by an error of more than 4 mm, and the gap between the marker ball and the socket resulted in a decrease in navigation accuracy by an error of more than 5 mm. The table-rotation error was found to be negligible. The errors can be avoided by ensuring that the fiducial markers are positioned appropriately on the scalp and the marker ball is fitted well in the marker socket. A phantom is useful for evaluating accuracy, particularly for evaluating errors intrinsic to different operating rooms. Periodic quality assurance by use of a phantom in each operating room might aid in maintaining the accuracy of neuronavigation.