Clinical impact of aortic valve replacement in patients with moderate mixed aortic valve disease.

Background: Information is scarce regarding the clinical implications of aortic valve replacement (AVR) for patients suffering from moderate mixed aortic valve disease (MAVD), characterized by a combination of moderate aortic stenosis (AS) and regurgitation (AR). The objective of this retrospective study was to explore the clinical effects of AVR in individuals with moderate MAVD. Methods: We examined the clinical data from patients with moderate MAVD and preserved left ventricular ejection fraction, who had undergone echocardiography in the period spanning from 2010 to 2018. Moderate AS was defined as aortic valve area index of 0.60-0.85 cm2/m2 and peak velocity of 3.0-4.0 m/s. Moderate AR was defined as a vena contracta width of 3.0-6.0 mm. The primary endpoint was a composite of all-cause death and heart failure hospitalization. Results: Among 88 patients (mean age, 74.4 ± 6.8 years; 48.9%, men), 44 (50.0%) required AVR during a median follow-up period of 3.3 years (interquartile range, 0.5-4.9). Mean values of specific aortic valve variables are as follows: aortic valve area index, 0.64 ± 0.04 cm2/m2; peak velocity, 3.40 ± 0.30 m/s; and vena contracta width, 4.1 ± 0.7 mm. The primary endpoint occurred in 32 (36.4%) patients during a median follow-up duration of 5.3 years (interquartile range, 3.2-8.0). Multivariable analysis revealed that AVR was significantly associated with the endpoint (hazard ratio, 0.248; 95% confidence interval, 0.107-0.579; p = 0.001) after adjusting for age, B-type natriuretic peptide, and the Charlson comorbidity index. Patients who underwent AVR during follow-up had significantly lower incidence rates of the endpoint than those managed with medical treatment (10.2% vs. 44.1% at 5 years; p < 0.001). Conclusions: Approximately half of the patients diagnosed with moderate MAVD eventually necessitated AVR throughout the period of observation, leading to positive clinical results. Vigilant tracking of these patients and watchful monitoring for signs requiring AVR during this time frame are essential.

Biomarkers associated with coronary high-risk plaques.

Vascular inflammation, lipid metabolism, and thrombogenicity play a key role not only in atherogenesis but also in the development of acute coronary syndromes. Biomarkers associated with coronary high-risk plaques defined according to intravascular imaging have not been systematically studied. A total of 69 patients with coronary artery disease who underwent both optical coherence tomography and intravascular ultrasound imaging, and who provided blood specimens were included. Comprehensive biomarkers for inflammation, lipid, and coagulation were analyzed. Composite models sought biomarker patterns associated with thin-cap fibroatheroma (TCFA) and "high-risk plaques" (TCFA and large plaque burden). Two different composite models were developed for TCFA, based on the finding that high sensitivity C-reactive protein (hsCRP), plasminogen activator inhibitor-1, fibrinogen, IL-6, homocysteine and amyloid A levels were elevated, and high-density lipoprotein cholesterol (HDL) and bile acid levels were decreased in these patients. Both composite models were highly accurate for detecting patients with TCFA (area under curve [AUC]: 0.883 in model-A and 0.875 in model-B, both p < 0.001). In addition, creatinine, hsCRP, fibrinogen, tumor necrosis factor-α, IL-6, homocysteine, amyloid A, HDL, prothrombin, and bile acid were useful for detecting patients with "high-risk plaques". Two composite models were highly accurate for detection of patients with "high-risk plaques" (AUC: 0.925 in model-A and 0.947 in model-B, both p < 0.001). Biomarkers useful for detection of patients with high-risk coronary plaques defined according to intravascular imaging have been identified. These biomarkers may be useful to risk stratify patients and to develop targeted therapy.Clinical Trial Registration https://www.umin.ac.jp/ctr/ , UMIN000041692. Biomarkers and high-risk plaques hsCRP, PAI-1, fibrinogen, IL-6, homocysteine, amyloid A, HDL, and bile acid were useful for detecting patients with TCFA. hsCRP, fibrinogen, IL-6, homocysteine, amyloid A, creatinine, TNFα, HDL, prothrombin, and bile acid were useful for detecting patients with "high-risk plaques" (plaque which has both TCFA and large plaque burden). White arrowhead denotes TCFA. Red and green dashed lines denote lumen area and external elastic membrane area, respectively.

Prognostic relevance of B-type natriuretic peptide in patients with moderate mixed aortic valve disease.

AIMS: Data on B-type natriuretic peptide (BNP) levels and adverse outcomes in patients with moderate mixed aortic valve disease (MAVD), defined as moderate aortic stenosis (AS) and regurgitation (AR), are scarce. Therefore, this study investigated the impact of BNP on the clinical outcomes in such patients. METHODS AND RESULTS: Clinical data from 81 patients (mean age, 74.1 ± 6.8 years; 50.6%, men) treated for moderate MAVD and left ventricular ejection fraction (LVEF) ≥ 50% during 2010-2018 were retrospectively analysed. Specific echocardiographic data of the study patients were LVEF of 57.8 ± 5.0%, aortic valve index of 0.64 ± 0.04 cm2 /m2 , peak aortic valve velocity of 3.38 ± 0.29 m/s, and AR vena contracta width of 4.2 ± 0.7 mm. The median BNP level was 61.4 pg/mL (interquartile range, 29.7-109.9). The primary endpoint was a composite of all-cause death, heart failure hospitalization, and aortic valve replacement, and its cumulative incidence at 5 years was 57.7%. Multivariable analysis revealed that age (hazard ratio, 1.079; 95% confidence interval, 1.028-1.133; P = 0.002) and BNP levels (hazard ratio, 1.028; 95% confidence interval, 1.003-1.053; P = 0.027) were significantly related to the endpoint; specifically, BNP > 61.4 pg/mL had significantly higher incidence rates of the endpoint than those with a BNP ≤ 61.4 pg/mL (70.3% vs. 45.5% at 5 years; P = 0.018). Compared with patients with BNP ≤ 61.4 pg/mL, those with BNP > 61.4 pg/mL had significantly worse left ventricular global longitudinal strain (-17.1 ± 3.6% vs. -18.7 ± 2.6%; P = 0.029), along with higher left ventricular mass index (116.9 ± 27.8 g/m2 vs. 103.5 ± 19.7 g/m2 ; P = 0.014), relative wall thickness (0.45 ± 0.07 vs. 0.42 ± 0.05; P = 0.022), left atrial volume index (46.0 ± 28.4 mL/m2 vs. 31.4 ± 10.3 mL/m2 ; P = 0.003), pulmonary artery systolic pressure (32.6 ± 9.7 mmHg vs. 28.2 ± 4.7 mmHg; P = 0.011), and prevalence of moderate or greater tricuspid regurgitation (15.0% vs. 0.0%; P = 0.012). CONCLUSIONS: Patients with moderate MAVD are at higher risk of unfavourable clinical outcomes, and age and BNP are independently related to the occurrence of adverse events. High BNP levels may reflect extravalvular cardiac damage in patients with moderate MAVD.

H2AX mRNA expression reflects DNA repair, cell proliferation, metastasis, and worse survival in breast cancer.

The phosphorylated histone variant, γ-H2AX, is known to play a key role in DNA damage repair. However, the clinical significance of H2AX mRNA expression in breast cancer remains unclear. Utilizing a bioinformatical approach, a total of 3594 breast cancer patients with clinical and transcriptomic data were investigated. Bioinformatical analysis showed that high expression of H2AX is associated with worse disease-free, disease-specific, and overall survival consistently in two independent cohorts. High H2AX expressing tumors were associated with upregulated DNA repair gene sets. Although H2AX was not predictive of chemotherapy response, it was significantly downregulated after effective chemotherapy or radio-chemotherapy. Notably, tumors with high H2AX expression were enriched for DNA replication and MYC targets gene sets, and associated with increased MKI67 expression, suggesting alterations in cell proliferation machinery. H2AX knockdown cells showed decreased cell proliferation as compared to the control cells. Finally, H2AX mRNA expression was higher in the metastatic clones as compared to the parental cells and in the metastatic tumors as compared to the primary tumors in patients, with higher H2AX mRNA expression found in advanced stage cancer patients. In conclusion, high H2AX mRNA expression is associated with increased DNA repair, cell proliferation, metastasis, and worse survival in breast cancer patients.

Impact of directional coronary atherectomy followed by drug-coated balloon strategy to avoid the complex stenting for bifurcation lesions.

Although the simple single stenting rather than complex double stenting is recommended on percutaneous coronary intervention (PCI) for bifurcation lesions, double stenting cannot always be avoided. We investigated the impact of directional coronary atherectomy (DCA), followed by drug-coated balloon (DCB) treatment to reduce the number of stents and avoid complex stenting in PCI for bifurcation lesions and short-term patency. DCA treatment without stents was attempted for 27 bifurcation lesions in 25 patients, of those, 26 bifurcation lesions in 24 patients were successfully treated and 3-month follow-up angiography and optical coherence tomography (OCT) were performed. Sixteen lesions (59.3%) were related to left main trunk distal bifurcations, and 7 (25.9%) were true bifurcation lesions. Among the true bifurcation lesions, 4 lesions (57.1%) needed 1 stent, and the other 3 lesions (42.9%) needed no stents. Among the non-true bifurcation lesions, 1 lesion (5.0%) needed bailout stent and other lesions (95.0%) needed no stents. According to DCA followed by DCB treatment, the angiographic mean diameter stenosis improved from 65.5 ± 15.0% to 7.8 ± 9.8%, and the mean plaque area in intravascular ultrasound improved from 80.4 ± 10.5% to 39.0 ± 11.5%, respectively. Angiographic and OCT late lumen loss values were 0.2 ± 0.6 mm and 1.4 ± 1.9 mm, respectively. No patient had in-hospital major adverse cardiac events (MACE) and 3-month MACE. In conclusion, compared with standard provisional side branch stenting strategy, DCA followed by DCB treatment might reduce the number of stents, avoid complex stenting for major bifurcation lesions and provide good short-term outcomes.

Long-term Outcome following Percutaneous Intervention of Intra-stent Coronary Occlusion and Evaluating the Different Treatment Modalities.

BACKGROUND: Angioplasty for ISR remains a challenge with relatively high rates of recurrence. Although there is a plethora of data on ISR, there is relatively less data on intra-stent-CTO. In this study, we explore the long-term clinical outcomes following angioplasty to intra-stent CTO and study the differences in clinical outcomes between three treatment-arms: POBA vs. DES vs. DCB. METHODS AND RESULTS: We evaluated all patients who underwent PCI to intra-stent CTO between 2011 and 2017. The endpoints used were: cardiac-death, TVMI, TLR, TVR, and MACE.During the study period, 403-patients with a mean age of 69.2 years had successful PCI to intra-stent CTO. 50% were diabetic, 38% had CKD and 32% had left ventricular dysfunction. 93% of cases were stable angina. 22% (n = 88) received only POBA, 28% (n = 113) received DCB and 50% (n = 202) received DES. During the median follow-up of 48-months, cardiac-death occurred in 5.8% (n = 23), TVMI in 4% (n = 16), TLR in 45.6% (n = 182), TVR in 48.7% (n = 194) and MACE of 46%. There were no differences in the hard endpoints between the 3treatment arms. However, the TLR and overall MACE were better in DCB and DES-groups as compared to POBA (TLR: 33%vs.42%vs.49%; p = 0.06); MACE (34% vs. 45% vs. 52%; p = 0.05). CONCLUSION: This is the first study that has focussed on the outcomes following angioplasty to intra-stent CTOs with a very long-term follow-up. The hard endpoints were low, although the TLR rates were high. In regards to treatment strategy, the DCB and DES provide relatively better outcomes than POBA.

A Novel AURKA Mutant-Induced Early-Onset Severe Hepatocarcinogenesis Greater than Wild-Type via Activating Different Pathways in Zebrafish.

Aurora A kinase (AURKA) is an important regulator in mitotic progression and is overexpressed frequently in human cancers, including hepatocellular carcinoma (HCC). Many AURKA mutations were identified in cancer patients. Overexpressing wild-type Aurka developed a low incidence of hepatic tumors after long latency in mice. However, none of the AURKA mutant animal models have ever been described. The mechanism of mutant AURKA-mediated hepatocarcinogenesis is still unclear. A novel AURKA mutation with a.a.352 Valine to Isoleucine (V352I) was identified from clinical specimens. By using liver-specific transgenic fish overexpressing both the mutant and wild-type AURKA, the AURKA(V352I)-induced hepatocarcinogenesis was earlier and much more severe than wild-type AURKA. Although an increase of the expression of lipogenic enzyme and lipogenic factor was observed in both AURKA(V352I) and AURKA(WT) transgenic fish, AURKA(V352I) has a greater probability to promote fibrosis at 3 months compared to AURKA(WT). Furthermore, the expression levels of cell cycle/proliferation markers were higher in the AURKA(V352I) mutant than AURKA(WT) in transgenic fish, implying that the AURKA(V352I) mutant may accelerate HCC progression. Moreover, we found that the AURKA(V352I) mutant activates AKT signaling and increases nuclear ß-catenin, but AURKA(WT) only activates membrane form ß-catenin, which may account for the differences. In this study, we provide a new insight, that the AURKA(V352I) mutation contributes to early onset hepatocarcinogenesis, possibly through activation of different pathways than AURKA(WT). This transgenic fish may serve as a drug-screening platform for potential precision medicine therapeutics.

Loss of lipid phosphatase SHIP1 promotes macrophage differentiation through suppression of dendritic cell differentiation.

SH2-containing inositol 5'-phosphatase-1 (SHIP1) deficiency in mice results in abnormal myeloid expansion, and proinflammatory conditions in the lung. However, the mechanisms involved in SHIP1-mediated regulation of myeloid differentiation remain unclear. Here we show that SHIP1 is a key regulator of early differentiation for dendritic cells (DCs). We also provide critical evidence to modify the function of SHIP1 in in vitro development of BMDCs using the recent framework of defining DCs. We found that loss of SHIP1 suppresses GM-CSF-induced formation of bone marrow-derived DC (BMDC) colonies, leading to reduced BMDC number in BM cell culture. The number of maturated BMDCs decreased in SHIP1-KO culture, due to reduction of immature BMDCs, suggesting SHIP1 is critical for lineage commitment rather than for maturation from myeloid precursors to DCs. We further showed that F4/80+/MHCIIlow BM macrophage-like cells (BMMs) were the main population of SHIP1-KO BM culture. Treatment of wild-type BM culture with 3 α-aminocholestane (3AC), a specific inhibitor for functional activity of SHIP1, caused a similar developmental defect in BMDCs as seen in SHIP1-KO cells, resulting in the absence of BMDC colony, and increased number of BMMs in BM culture. In conclusion, our results suggest that differentiation of BMDCs are markedly impaired under SHIP1 deficient condition, which causes skewed development of myeloid lineage cells manifested as pathological conditions associated with an excess of macrophage population.

A methyl-sensitive element induces bidirectional transcription in TATA-less CpG island-associated promoters.

How TATA-less promoters such as those within CpG islands (CGI) control gene expression is still a subject of active research. Here, we have identified the "CGCG element", a ten-base pair motif with a consensus sequence of TCTCGCGAGA present in a group of promoter-associated CGI-enriched in ribosomal protein and housekeeping genes. This element is evolutionarily conserved in vertebrates, found in DNase-accessible regions and employs RNA Pol II to activate gene expression. Through analysis of capped-nascent transcripts and supporting evidence from reporter assays, we demonstrate that this element activates bidirectional transcription through divergent start sites. Methylation of this element abrogates the associated promoter activity. When coincident with a TATA-box, directional transcription remains CGCG-dependent. Because the CGCG element is sufficient to drive transcription, we propose that its unmethylated form functions as a heretofore undescribed promoter element of a group of TATA-less CGI-associated promoters.

The screening of a microRNA expression during development of human macrophages and mouse dendritic cells.

There is increasing evidence showing specific roles of microRNA in cell differentiation and cancer progression. Here we examine miRNA profiles during maturation of monocytes and bone marrow-derived dendritic cells (BMDCs) in human and mouse, respectively. We have identified significant changes of various miRNA expression during monocyte and BMDC monocyte development via miRNA microarrays, confirmed by quantitative PCR. Increases in miR155 expression positively correlated with increasing maturity of monocyte and BMDC in both mouse and human microarrays, indicating its importance in development. We describe a requirement of miR155 for MHCII expression during GM-CSF-induced development and LPS-induced maturation of DCs, suggesting reduced immune function of DC when miR155 is absent. Our study suggests that miRNAs might have an important role in differentiation of myeloid cell such as dendritic cells and macrophages.

Fibersol-2 induces apoptosis of Apc-deficient colorectal Cancer (SW480) cells and decreases polyp formation in Apc MIN mice.

The consumption of dietary fibers has been implicated with a lowered risk of human colorectal cancer. Proposed mechanisms involve alterations in the stool consistency, transit time, and formation of short-chain fatty acid by dietary fiber fermentation, and the reorganization of gut microbiota. Here we show that Fibersol-2, a digest-resistant maltodextrin, not only inhibits proliferation of colorectal SW480 cancer cell lines by increasing reactive oxygen species (ROS), but decreases the numbers of the adenoma count in Multiple Intestinal Neoplasia (MIN) mice carrying a mutation in the Adenomatous Polyposis Coli gene by 84 d of age. These observations provide direct evidence that Fibersol-2 intrinsically contains anti-cancer activity, independent of the intestinal metabolism and any potential interactions with the microbiota.

Mutations in BRAT1 cause autosomal recessive progressive encephalopathy: Report of a Spanish patient.

We describe a 4-year-old male child born to non-consanguineous Spanish parents with progressive encephalopathy (PE), microcephaly, and hypertonia. Whole exome sequencing revealed compound heterozygous BRAT1 mutations [c.1564G > A (p.Glu522Lys) and c.638dup (p.Val214Glyfs*189)]. Homozygous and compound heterozygous BRAT1 mutations have been described in patients with lethal neonatal rigidity and multifocal seizure syndrome (MIM# 614498). The seven previously described patients suffered from uncontrolled seizures, and all of those patients died in their first months of life. BRAT1 acts as a regulator of cellular proliferation and migration and is required for mitochondrial function. The loss of these functions may explain the cerebral atrophy observed in this case of PE. This case highlights the extraordinary potential of next generation technologies for the diagnosis of rare genetic diseases, including PE. Making a prompt diagnosis of PE is important for genetic counseling and disease management.

Tumor suppression by resistant maltodextrin, Fibersol-2.

Resistant maltodextrin Fibersol-2 is a soluble and fermentable dietary fiber that is Generally Recognized As Safe (GRAS) in the United States. We tested whether Fibersol-2 contains anti-tumor activity. Human colorectal cancer cell line, HCT116, and its isogenic cells were treated with FIbersol-2. Tumor growth and tumorigenesis were studied in vitro and in vivo. Apoptotic pathway and generation of reactive oxygen species (ROS) were investigated. We discovered that Fibersol-2 significantly inhibits tumor growth of HCT116 cells by inducing apoptosis. Fibersol-2 strongly induces mitochondrial ROS and Bax-dependent cleavage of caspase 3 and 9, which is shown by isogenic HCT116 variants. Fibersol-2 induces phosphorylation of Akt, mTOR in parental HCT116 cells, but not in HCT116 deficient for Bax or p53. It prevents growth of tumor xenograft without any apparent signs of toxicity in vivo. These results identify Fibersol-2 as a mechanism-based dietary supplement agent that could prevent colorectal cancer development.

Nedd4 family interacting protein 1 (Ndfip1) is required for ubiquitination and nuclear trafficking of BRCA1-associated ATM activator 1 (BRAT1) during the DNA damage response.

During injury, cells are vulnerable to apoptosis from a variety of stress conditions including DNA damage causing double-stranded breaks. Without repair, these breaks lead to aberrations in DNA replication and transcription, leading to apoptosis. A major response to DNA damage is provided by the protein kinase ATM (ataxia telangiectasia mutated) that is capable of commanding a plethora of signaling networks for DNA repair, cell cycle arrest, and even apoptosis. A key element in the DNA damage response is the mobilization of activating proteins into the cell nucleus to repair damaged DNA. BRAT1 is one of these proteins, and it functions as an activator of ATM by maintaining its phosphorylated status while also keeping other phosphatases at bay. However, it is unknown how BRAT1 is trafficked into the cell nucleus to maintain ATM phosphorylation. Here we demonstrate that Ndfip1-mediated ubiquitination of BRAT1 leads to BRAT1 trafficking into the cell nucleus. Without Ndfip1, BRAT1 failed to translocate to the nucleus. Under genotoxic stress, cells showed increased expression of both Ndfip1 and phosphorylated ATM. Following brain injury, neurons show increased expression of Ndfip1 and nuclear translocation of BRAT1. These results point to Ndfip1 as a sensor protein during cell injury and Ndfip1 up-regulation as a cue for BRAT1 ubiquitination by Nedd4 E3 ligases, followed by nuclear translocation of BRAT1.

Cell Differentiation and Checkpoint.

DNA damage is induced in many types of cells by internal and external cell stress. When DNA is damaged, DNA Damage Response (DDR) programs are activated to repair the DNA lesions in order to preserve genomic integrity and suppress subsequent malignant transformation. Among these programs is cell cycle checkpoint that ensures cell cycle arrest and subsequent repair of the damaged DNA, apoptosis and senescence in various phases of the cell cycle. Moreover, recent studies have established the cell differentiation checkpoint, the other type of the checkpoint that is specifically activated in the course of differentiation. We will discuss the evidences that support the link between DNA damage proteins and C2C12 cell differentiation.

Distinct DNA damage determines differential phosphorylation of Chk2.

Checkpoint kinase 2 (Chk2) has been implicated in DNA damage signaling. By using BJ human fibroblasts, HCT116 colorectal cancer cells and HeLa cervical cancer cells, we further detailed phosphorylation kinetics of Chk2 under treatment with neocarcinostatin (NCS) or doxorubicin (Dox). After NCS treatment, phosphorylation of Chk2 Thr68 occurs in 3 min, followed by phosphorylation of Ser19 and Ser33/35. In ATM deficient fibroblasts, NCS does not induce phosphorylation of NBS1 Ser343 and Chk2 Ser19 and Ser33/35, however Chk2 Thr68 is still phosphorylated, indicating that ATM is essential for phosphorylation of these residues when treated with NCS. By using Chk2-deficient HCT116 cells re-expressing phospho-mutant Chk2 (T68A), we found that inhibition of Thr68 phosphorylation enhances Ser19 phosphorylation in NCS treated cells. Interestingly, in contrast to NCS, Dox does not induce Ser33/35 phosphorylation in HeLa and HCT116 cells. Phosphorylation of Thr68 is sustained until 3 to 4 hours, and phosphorylation of Ser19 occurs 70 to 80 min after Dox treatment. These results demonstrate that Chk2 s involved in the early stages of DNA damage response. Differential phosphorylation kinetics of these residues suggests that DNA damage determines intermolecular and intramolecular interaction of Chk2, which may regulate phosphorylation.

BRAT1 deficiency causes increased glucose metabolism and mitochondrial malfunction.

BACKGROUND: BRAT1 (BRCA1-associated ATM activator 1) interacts with both BRCA1, ATM and DNA-PKcs, and has been implicated in DNA damage responses. However, based on our previous results, it has been shown that BRAT1 may be involved in cell growth and apoptosis, besides DNA damage responses, implying that there are undiscovered functions for BRAT1. METHODS: Using RNA interference against human BRAT1, we generated stable BRAT1 knockdown cancer cell lines of U2OS, Hela, and MDA-MA-231. We tested cell growth properties and in vitro/in vivo tumorigenic potentials of BRAT1 knockdown cells compared to control cells. To test if loss of BRAT1 induces metabolic abnormalities, we examined the rate of glycolysis, ATP production, and PDH activity in both BRAT1 knockdown and control cells. The role of BRAT1 in growth signaling was determined by the activation of Akt/Erk, and SC79, Akt activator was used for validation. RESULTS: By taking advantage of BRAT1 knockdown cancer cell lines, we found that loss of BRAT1 expression significantly decreases cell proliferation and tumorigenecity both in vitro and in vivo. Cell migration was also remarkably lowered when BRAT1 was depleted. Interestingly, glucose uptake and production of mitochondrial ROS (reactive oxygen species) are highly increased in BRAT1 knockdown HeLa cells. Furthermore, both basal and induced activity of Akt and Erk kinases were suppressed in these cells, implicating abnormality in signaling cascades for cellular growth. Consequently, treatment of BRAT1 knockdown cells with Akt activator can improve their proliferation and reduces mitochondrial ROS concentration. CONCLUSIONS: These findings suggest novel roles of BRAT1 in cell proliferation and mitochondrial functions.

Decreased DNA repair activity in bone marrow due to low expression of DNA damage repair proteins.

The bone marrow (BM) is one of the organs that is sensitive to acute exposure of ionizing radiation (IR); however, the mechanism of its high sensitivity to IR remains to be elucidated. BM is differentiated into dendritic cells (DC) with granulocyte macrophage-colony stimulating factor (GM-CSF). Using this in vitro model, we studied whether radiosensitivity is distinctly regulated in undifferentiated and differentiated BM. We discovered that levels of DNA damage repair (DDR) proteins are extremely low in BM, and they are markedly increased upon differentiation to DC. Efficiency of both homologous recombination (HR)- and non-homologous end joining (NHEJ)-mediated repair of DNA double strand breaks (DSBs) is much lower in BM compared with that of DC. Consistent with this, immunofluorescent γH2AX is highly detected in BM after IR. These results indicate that increased radiosensitivity of BM is at least due to low expression of the DNA repair machinery.

A novel aurora-A inhibitor, BPR1K0609S1, sensitizes colorectal tumor cells to 5-fluorofracil (5-FU) treatment.

Small synthetic compounds have been implicated in treatment of human cancers. We have synthesized a small compound, BPR1K0609S1 (hereafter, BP), which inhibits Aurora-A kinase. In the present study, we studied the mechanism of BP suppression of tumorigenesis induced by Aurora-A. Given our previous results that inactivation of p53 accelerates MMTV-Aurora-A-mediated tumorigenesis in vivo, we studied the roles of p53 pathway using the isogenic human colon carcinoma cell lines of HCT116, in which p53, Puma, Bax, p21 or Chk2 is deleted. When these isogenic cell lines are treated with BP for 48 h, accumulation of G2M phase and aneuploidy are commonly observed, and HCT116 p21(-) cells show increase in apoptosis. In xenograft assay, s.c. injection of BP efficiently inhibits tumorigenesis of HCT116 deficient for Chk2 or p21. Re-transplantation of BP-resistant tumors indicates that these resistant cells do not acquire advanced tumor growth. Significantly, 5-FU (5-fluorouracil) treatment further induces apoptosis of BP-resistant HCT116 deficient for Chk2 or Puma. These results demonstrate that p21 deficiency enhances BP-mediated suppression of tumor growth, and that BP and 5-FU can collaborate for tumor regression.