ABSTRACT
Homologous recombination (HR) is a major repair pathway of DNA double-strand breaks and is closely related to carcinogenesis. HR deficiency has been established as a therapeutic target. The aim of this study was to elucidate the functions of a novel HR factor, Mediator complex subunit 1 (MED1), and its association with BRCA1. Formation of the MED1/BRCA1 complex was examined by immunoprecipitation and GST-pull down assays. The transcription cofactor role of BRCA1 was evaluated using luciferase assays. The roles of MED1 on DNA damage response and HR were analyzed by immunofluorescence and HR assays. R-loop accumulation was analyzed using immunofluorescence. R-loop-induced DNA damage was analyzed by comet assays. Immunoprecipitation and GST-pull down assays demonstrated that MED1 is a novel binding partner of BRCA1 and binds to the BRCT domain. Luciferase assays showed that MED1 potentiated the transcription ability of BRCT by two-fold. In MED1-depleted cells, recruitment of HR genes, such as RPA and γH2AX, to DNA damage sites was severely impaired. HR assays showed that MED1 knockdown significantly decreased HR activity. R-loop nuclear accumulation and R-loop-induced comet tails were observed in MED1-depleted cells. We conclude that the transcription factor MED1 contributes to the regulation of the HR pathway and R-loop processing.
Subject(s)
Mediator Complex Subunit 1 , R-Loop Structures , BRCA1 Protein/genetics , BRCA1 Protein/metabolism , DNA , DNA Repair , Homologous Recombination , Mediator Complex Subunit 1/genetics , Transcription Factors/metabolismABSTRACT
Chemotherapy plays an important role in the treatment of patients with gynecological cancers. Delivering anticancer drugs effectively to tumor cells with just few side effects is key in cancer treatment. Lipid bubbles (LB) are compounds that increase the vascular permeability of the tumor under diagnostic ultrasound (US) exposure and enable the effective transport of drugs to tumor cells. The aim of our study was to establish a novel drug delivery technique for chemotherapy and to identify the most effective anticancer drugs for the bubble US-mediated drug delivery system (BUS-DDS) in gynecological cancer treatments. We constructed xenograft models using cervical cancer (HeLa) and uterine endometrial cancer (HEC1B) cell lines. Lipid bubbles were injected i.v., combined with either cisplatin (CDDP), pegylated liposomal doxorubicin (PLD), or bevacizumab, and US was applied to the tumor. We compared the enhanced chemotherapeutic effects of these drugs and determined the optimal drugs for BUS-DDS. Tumor volume reduction of HeLa and HEC1B xenografts following cisplatin treatment was significantly enhanced by BUS-DDS. Both CDDP and PLD significantly enhanced the antitumor effects of BUS-DDS in HeLa tumors; however, volume reduction by BUS-DDS was insignificant when combined with bevacizumab, a humanized anti-vascular endothelial growth factor mAb. The BUS-DDS did not cause any severe adverse events and significantly enhanced the antitumor effects of cytotoxic drugs. The effects of bevacizumab, which were not as dose-dependent as those of the two drugs used prior, were minimal. Our data suggest that BUS-DDS technology might help achieve "reinforced targeting" in the treatment of gynecological cancers.
Subject(s)
Antineoplastic Agents/administration & dosage , Endometrial Neoplasms/drug therapy , Liposomes/administration & dosage , Uterine Cervical Neoplasms/drug therapy , Animals , Antineoplastic Agents/pharmacology , Bevacizumab/administration & dosage , Bevacizumab/pharmacology , Cell Line, Tumor , Cisplatin/administration & dosage , Cisplatin/pharmacology , Doxorubicin/administration & dosage , Doxorubicin/analogs & derivatives , Doxorubicin/pharmacology , Drug Delivery Systems , Female , HeLa Cells , Humans , Injections, Intravenous , Liposomes/chemistry , Mice , Nanoparticles , Polyethylene Glycols/administration & dosage , Polyethylene Glycols/pharmacology , Ultrasonography , Xenograft Model Antitumor AssaysABSTRACT
We report the cases of a father and his son with spinocerebellar ataxia type 7 (SCA7), a disorder rarely reported in Japan. The father had noticed dysarthria at age 38, and gait instability at age 46. Visual disturbance was noted 3 years later. Neurological examination at age 54 revealed visual disturbance, dysarthria, and cerebellar ataxia in all four extremities and the trunk. Cranial MRI showed moderate atrophy of the brain stem and cerebellar hemispheres. However, no retinal degeneration was found. The son was 16 years old at our first examination. Since age 6, his visual acuity began to decrease; at age 10, he noticed clumsiness in his hands. Six years later he began to experience gait instability. Neurological examination revealed visual disturbance and cerebellar ataxia. He was diagnosed with SCA7 by genetic analysis. His ophthalmologic examination showed retinal degeneration without pigmented spots, which is different from those of retinal phenotypes previously described in SCA7.
