Growth suppression and mitotic defect induced by JNJ-7706621, an inhibitor of cyclin-dependent kinases and aurora kinases

Aurora kinases and cyclin-dependent kinases, which play critical roles in the cell cycle and are frequently overexpressed in a variety of tumors, have been suggested as attractive targets for cancer therapy. JNJ-7706621, a recently identified dual inhibitor of these kinases, is reported to induce cell cycle arrest, endoreduplication, and apoptosis. In the present study, we further investigated the molecular mechanisms underlying these effects. The inhibitor arrested various cells at G2 phase at low concentration, and at both G1 and G2 phases at high concentration. JNJ-7706621 did not prevent localization of Aurora A to the spindle poles, but did inhibit other centrosomal proteins such as TOG, Nek2, and TACC3 in early mitotic phase. Similarly, the drug did not prevent localization of Aurora B to the kinetochore, but did inhibit other chromosomal passenger proteins such as Survivin and INCENP. In the cells exposed to JNJ-7706621 after nocodazole release, Aurora B, INCENP, and Survivin became relocated to the peripheral region of chromosomes, but Plk1 and Prc1 were localized on microtubules in later mitotic phase. Treatment of nocodazole-synchronized cells with JNJ-7706621 was able to override mitotic arrest by preventing spindle checkpoint signaling, resulting in failure of chromosome alignment and segregation. Injection of the drug significantly inhibited the growth of TC135 Ewing's sarcoma cells transplanted into athymic mice by cell cycle arrest and apoptosis. JNJ-7706621 is a unique inhibitor regulating cell cycle progression at multiple points, suggesting that it could be useful for cell cycle analysis and therapy of various cancers, including Ewing's sarcoma.

Radiosensitivity of human biliary tract cancer cell lines in vitro

The prognosis of biliary tract cancer is still poor. Although a number of clinical studies have suggested a role for radiation therapy in advanced biliary tract cancer, its value remains controversial. Moreover, the intrinsic radiosensitivity of bile duct cancer cell lines has not been described, and the molecular basis for the response of these tumors to ionizing radiation is poorly understood. The present study was designed to examine the intrinsic radiation sensitivity of human biliary tract cancer cells and its relationship to p53 status. Radiation response expressed by the parameters n, D-0, D-10, alpha, beta, (D) over bar (mean inactivation dose), and SF, of seven cell lines derived from gallbladder and bile duct cancers was determined. The results suggest that biliary tract cancer cell lines as a group are relatively radioresistant. The mean X-ray survival parameters for these seven cancer cell lines were D-0=2.13+/-0.29 Gy, D-10=5.73+/-0.59 Gy, (D) over bar=2.76+/-0.25 Gy, alpha=0.25+/-0.03, and SF2=0.54+/-0.05. One of the seven lines was more radiosensitive than the others (D-0=0.77+/-0.02 Gy, D-10=2.95+/-0.06 Gy, (D) over bar=1.57 Gy, alpha=0.35, SF2=0.35+/-0.03). Five of six lines examined expressed mutant p53 including the radiosensitive line; one radioresistant line expressed wild-type p53. Thus, although loss of wild-type p53 expression occurred frequently in these biliary cancer cell lines, radiosensitivity did not correlate with p53 status. In view of the intrinsic radioresistance of this type of tumor cell coupled with the poor tolerance of surrounding normal tissues, maximal surgical debulking and intraoperative radiation therapy may contribute to increased local control over resection and/or conventional fractionated radiotherapy.

A simple freezing medium for serum-free cultured cells

Methylcellulose was found to protect serum-free cultured cells from the deleterious effects of freezing and thawing. We have formulated a simple medium suitable for freezing serum-free cultured cells that consists of 0.1% methylcellulose, 10% dimethylsulfoxide, and MEM or any other serum-free culture medium.

Design of ridge filters for spread-out Bragg peaks with Monte Carlo simulation in carbon ion therapy

Spread-out Bragg peaks made by ridge filters or wheel range modulators are used in charged particle therapy with passive methods to achieve uniform biological responses in irradiated tumors. Following the biological responses needed to design the ridge filters, which were developed at the National Institute of Radiological Sciences in Japan, new ridge filters were designed using recent developments in heavy-ion reactions and dosimetry. The Monte Carlo code of Geant4 was used to calculate the qualities of carbon ion beams in a water phantom. The results obtained from the simulation were corrected so that they agreed with the measurements of depth dose distributions. The calculations of biological responses to fragments other than carbon ions were assumed to be for helium ions. The measured dose distributions with the designed ridge filters were compared to the calculated distributions. A beam modifying system using this adaptable method was successively applied to carbon ion therapy at Gunma University.

Improvement of electrical conductivity while maintaining a high-transmittance of graphene oxide/MWCNT film by hydrazine reduction

In this study, we attempted to synthesize a transparent electrode with a composite of along graphene with multi-walled carbon nanotubes (MWCNT). Hydrazine was used for the reduction process. After the treatment with hydrazine, the sheet resistance was reduced from over 10 Momega/sq. The longest dip time sample (reduced GO/MWCNT-5, RGO/MWCNT-5) had the lowest sheet resistance (114 komega/sq). The reason for this decrease is likely due to the fact that the concentration of MWCNT in the deposited film increased with increases in the deposition time based on the higher density of the MWCNT. Although the transmittance decreased with decreases in the sheet resistance, the transmittances of all the samples were approximately 80% at 550 nm. We succeed in synthesizing a film that maintains transmittance (80%) despite a decreasing sheet resistance.

Improvement of visible light photocatalytic acetaldehyde decomposition of bismuth vanadate/silica nanocomposites by cocatalyst loading

Photocatalytic activity of bismuth vanadate (BiVO(4)) for acetaldehyde decomposition under visible light irradiation was improved by inclusion of a nanocomposition of silica as an adsorbent material and loading of platinum (Pt) or trivalent iron ion (Fe(3+)) as reduction cocatalysts. Addition of silica enhanced photocatalytic activity due to improvement of adsorption ability, but total decomposition of acetaldehyde was not observed within 24h of visible light irradiation. For further improvement of photocatalytic activity, BiVO(4) with an optimized amount of silica composition were modified with Pt or Fe(3+). Photodeposition of Pt greatly increased photocatalytic activity, and acetaldehyde was totally decomposed within 24h of visible light irradiation.