Improving the quality of sleep with an optimal pillow: a randomized, comparative study

Because sleep comprises one-third of a person's life, using an optimal pillow for appropriate neck support to maintain cervical curve may contribute to improve quality of sleep. Design of orthopedic pillow conforms to orthopedic guidelines to ensure the right support of the cervical curve. The aim of this study was to investigate effect of different pillow shape and content on cervical curve, pillow temperature, and pillow comfort. A feather pillow is regarded as a standard pillow, and a memory foam pillow is one of the most popular pillows among pillow users. We, therefore, compared these two pillows with an orthopedic pillow. Twenty healthy subjects (10 men and 10 women; age range, 21-30 years) participated in the study. Each subject was asked to assume the supine position with 3 different pillows for 30 minute in each trial and then cervical curve, pillow temperature, and pillow comfort were measured. When comparing the cervical curve of the 3 different pillows, that of the orthopedic pillow was significantly higher than that of the other 2 pillows (p < 0.001). The degree of temperature increase was significantly lower for the orthopedic pillow than for the memory foam and feather pillows (p < 0.001). The visual analog scale (VAS) score of pillow comfort was significantly higher in orthopedic pillow than the other 2 pillows. This study shows that pillow shape and content plays a crucial role in cervical curve, pillow temperature, and pillow comfort and orthopedic pillow may be an optimal pillow for sleep quality.

Effects of respiratory muscle and endurance training using an individualized training device on the pulmonary function and exercise capacity in stroke patients

BACKGROUND

Because respiratory muscle function plays a strong role in exercise capacity and cardiopulmonary response to exercise, systematic training and measurement of respiratory muscle function should be considered in stroke patients. The purpose of this study was to determine whether an individualized respiratory muscle training device combined with conventional physical therapy exercise can improve the pulmonary function and exercise capacity of stroke patients.

MATERIAL AND METHODS

Twenty stroke patients were randomly assigned to an exercise group (n=10) or a control group (n=10). Over 4 weeks, each group participated in exercise training interventions 3 times per week. In each session, the control group received basic exercise treatments for 30 min, followed by an automated full-body workout for 20 min. The exercise group performed the same exercise regimen as the control group, as well as an additional respiratory muscle training regimen using a respiratory exercise device for 20 min.

RESULTS

Pulmonary function of forced vital capacity (FVC), forced expiratory volume at 1 s (FEV1), FEV1/FVC, and peak expiratory flow (PEF) and exercise capacity of a 6-min walking test and Shortness of Breath Modified Borg Dyspnea Scale (SBMBDS) scores were assessed before and after the training. A significant intergroup difference was observed in the FVC, FEV1, PEF, 6MWT, and SBMBDS scores (p<0.05).

CONCLUSIONS

These findings suggest that exercise of the respiratory muscles using an individualized respiratory device had a positive effect on pulmonary function and exercise capacity and may be used for breathing rehabilitation in stroke patients.

Elderly health and literature therapy: a theoretical review

Recently, the problems of old age have been discussed in terms of two aspects: preventive and therapeutic approach. The previous studies on the preventive aspect have been mostly concerned with the educational preparation for successful approach to elderly, directing focus toward the transitional period of the old age. Most research into the therapeutic aspect on the elderly diseases has focused on organic mental disorders such as dementia and functional mental diseases such as depression. This study aims to suggest the preventive and new therapeutic possibility in old people through combining the elderly health with literature. First, the research results regarding the social background for the elderly problems indicate that geriatric diseases increase in proportion to the increase of the population. Secondly, for the literature therapy, it is initially required to seek a comprehensive understanding about the health of the elderly through the phased consideration for the elderly problems. Thirdly, for the treatment of geriatric diseases by using literature, it is necessary to develop more active and integrative literature therapy than passive bibliotherapy. Literature therapy is the use of literature in the treatment of people with emotional or mental illness. Fourthly, theoretical approach should be considered for the health of the elderly and the literature therapy. From a literary approach, the literature therapy can help the study on geriatric diseases such as dementia and depression. Thus, the program for the health of geriatric issues and literature therapy should be developed as the next step in the future.

Structural modelling and molecular characterization of omega-class glutathione S-transferase 2 from Drosophila melanogaster

Glutathione S-transferase omega (GSTO) is a recently identified Glutathione S-transferase (GST), and it has several known functions and variable distribution patterns in many organisms. In Drosophila, GstO2 exists as two isoforms, GstO2A and GstO2B. Despite the high sequence homology between the two GstO2 isoforms, they have different physiological functions. In the present study, we characterized the structural and molecular properties of Drosophila melanogaster GstO2 isoforms. Homology modelling of GstO2s using I-TASSER servers for protein structure and function prediction revealed that the two GstO2s have different electropotential surface distributions and different shapes of the substrate-binding sites. The recombinant GstO2s have native molecular weights of ∼60 kDa. GstO2s have similar optimum conditions for enzymatic reactions at pH 8.0 and 40 °C. The kinetic parameters of the reduction of dehydroascorbate by these two GstO2s were determined. Collectively, our results provide structural insights into the different substrate profiles of the GstO2 isoforms.

Protective effect of anti-oxidants on endothelial function in young Korean-Asians compared to Caucasians

Background

Previous studies show that Asians have an impaired blood flow response (BFR) to occlusion after a single high fat (HF) meal. The mechanism is believed to be the presence and susceptibility to high free radicals in their blood. The free radical concentration after a HF meal has not been examined in Asians. Further the BFR to heat after a single HF meal in Koreans has not been measured.

Material/Methods

This study evaluated postprandial endothelial function by measuring the BFR to vascular occlusion and local heat before and after a HF meal and the interventional effects of anti-oxidant vitamins on improving endothelial function in young Korean-Asians (K) compared to Caucasians (C) with these assessments. Ten C and ten K participated in the study (mean age 25.3±3.6 years old). BFR to vascular occlusion and local heat and oxidative stress were assessed after a single low fat (LF) and HF meal at 2 hours compared to baseline. After administration of vitamins (1000 mg of vitamin C, 800 IU of vitamin E, and 300 mg of Coenzyme Q-10) for 14 days, the same measurements were made.

Results

This study showed that the skin BFR to vascular occlusion and local heat following a HF meal significantly decreased and free radicals significantly increased at 2 hours compared to baseline in K (p<.001), but not in C. When vitamins were given, the BFR to vascular occlusion and local heat before and after HF meal were not significantly different in K and C.

Conclusions

These findings suggest that even a single HF meal can reduce endothelial response to stress through an oxidative stress mechanism but can be blocked by antioxidants, probably through scavenging free radicals in K. Since endothelial function improved even before a HF meal in K, endothelial damage from an Americanized diet may be reduced in K by antioxidants.

Differences in endothelial function between Korean-Asians and Caucasians

Background

The vascular endothelium plays an integral role in maintaining vascular homeostasis, including the regulation of blood flow, vascular tone, and platelet aggregation. The aim of this study was to see if there were any differences in endothelial function between Koreans and Caucasians.

Material/Methods

This was accomplished by 2 measures of endothelial function – the response to local heat and the response to vascular occlusion. Ten Caucasian and 10 Korean male and female subjects participated (<35 years old). Endothelial function was assessed by the skin blood flow response to local heat using a thermode for 6 minutes at 3 temperatures (38°C, 40°C and 42°C) and by vascular occlusion for 4 minutes followed by release and measurement of skin blood flow for 2 minutes.

Results

When applying 6 minutes of local heat at 3 different temperatures (38°C, 40°C, and 42°C), the skin blood flows were significantly higher for all temperatures in Caucasians as compared with Koreans, with peak blood flow of 223±48.1, 413.7±132.1, and 517.4±135.8 flux in Caucasians and 126.4±41.3, 251±77.9, and 398±97.2 flux in Koreans, respectively (p=0.001). Results of this study support the idea that the skin blood flow response to occlusion was significantly higher in Caucasians (peak 411.9±88.9 flux) than Koreans (peak 332.4±75.8 flux) (p=0.016).

Conclusions

These findings suggest that Koreans may have lower endothelial function than Caucasians, which may be explained, in part, by genetic variations between the 2 ethnic groups.

Abstract P2-09-17: Limited Gene Expression Profiling as Predictor of Response to Neoadjuvant Chemotherapy (NCT) with Docetaxel, Doxorubicin, Cyclophosphamide (TAC), or AC and Nab-Paclitaxel and Carboplatin +/− Trastuzumab in Patients (pts) with Locally Advanced (LABC) Stage II-III and Inflammatory Breast Cancer (IBC)

Background: Pathologic complete response (pCR) following neoadjuvant therapy (NCT) may predict for improved survival. Hence, more effective and individualized/targeted NCT regimens in conjunction with molecular markers that predict for both response and/or resistance are needed. Materials and Methods: 119 evaluable pts (121 enrolled) with stages II/III LABC/IBC were prospectively randomized to receive 6 cycles of docetaxel 75 mg/m2, doxorubicin 50 mg/m2, cyclophosphamide 500 mg/m2 with filgrastim support (TAC, arm A) versus a novel regimen of A 60 mg/m2 and C 600 mg/m2 given every 2 weeks x 4, followed by 3 weekly doses of carboplatin (AUC 2) and nab-paclitaxel 100 mg/m2 repeated as 28 day cycles x 3 (arm B). Pts with HER2 overexpressing (HER2+) BC received NCT similar to arm B, but with the addition of 12 weekly doses of trastuzumab given together with carboplatin and nab-paclitaxel (arm C). Core biopsies were performed prior to NCT and samples from 10 micron thick slides of formalin-fixed and paraffin-embedded (FFPE) breast cancer tissue were microdissected, and RNA was extracted for assessment of gene expression by RT-PCR for a panel of genes involved in cell proliferation, tumor suppression, DNA repair, and apoptosis. The following genes were evaluated: HER2/neu, IGF-1R, JAK2, STAT3, EGFR, BRCA1 and 2, PARP1, ERCC1, Topoisomerase 2-alpha, BBC3 (PUMA), p21, p27, IRF1, Beta-catenin, and SPARC, with actin as control. Responses were separated as complete or other response, and the Wilcoxon test was applied. Results: Neoadjuvant response assessment and sufficient amount of RNA following microdissection of primary tumor slides were available in 66/121 pts (55%). These 66 pts had similar characteristics to the entire cohort of enrolled pts. The median age was 51 yrs (range 30-69), and pts were treated for stage II/III BC (N=32, N=34, respectively, with 10 IBC cases). 37 pts were treated on Arms A and B (HER2- cohorts), and 29 on arm C (HER2+ cohort). pCR rates were 5/37 (14%) in groups A and B (of this set) combined, and 14/29 (48%) in group C (HER2+). For all arms/pts combined, overexpression of HER2, EGFR, and BRCA2, and low expression of p27, and IGFR1 were observed in pts with pCR, in comparison to pts not achieving pCR (P&lt;0.05). When the analysis was restricted to HER2 negative cases (Arms A and B), BRCA2, JAK2 overexpression, and low expression of IGF1R were associated with pCR (P&lt;0.05). Conclusion: Limited gene array analysis from microdissected FFPE specimens procured prior to NCT is feasible, and there is sufficient evidence in this limited data set to suggest that the specifc gene expression levels tested may play an important role in determining response to NCT both in HER2+ and HER2-, locally advanced, and inflammatory breast cancer.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-09-17.

Basal-, Luminal-, and HER2- Molecular Subtype, and the MammaPrint 70-Gene Signature as Predictors of Response to Neoadjuvant Chemotherapy (NCT) with Docetaxel, Doxorubicin, Cyclophosphamide (TAC), or AC and Nab-Paclitaxel and Carboplatin +/- Trastuzumab in Patients (Pts) with Stage II-III and Inflammatory Breast Cancer (BC)

Background: Pathologic complete response (pCR) and minimal residual cancer burden (RCB scores of 0 [pCR]-1[near CR]) after NCT may predict for improved survival (Symmans et al. J Clin Oncol 25:4414-22, 2007). Hence, improved NCT regimens in conjunction with molecular markers that predict for both response and/or resistance are needed. Materials and Methods: 115 pts with stages II-III BC were to be prospectively randomized to receive 6 cycles of docetaxel 75 mg/m2, doxorubicin 50 mg/m2, cyclophosphamide 500 mg/m2 with filgrastim support (TAC, arm A) versus a novel regimen of A 60 mg/m2 and C 600 mg/m2 given every 2 weeks x 4, followed by 3 weekly doses of carboplatin (AUC 2) and nab-paclitaxel 100 mg/m2 repeated as 28 day cycles x 3 (arm B). Pts with HER2 + BC received NCT similar to arm B, but with the addition of 12 weekly doses of trastuzumab given together with carboplatin and nab-paclitaxel (arm C). Core biopsies were performed prior to NCT and were preserved fresh frozen. 70-gene (MammaPrint™) profiling and 80-gene profiling (van de Vijver et al. NEJM 347:1999-2009, 2002) to categorize all tumors for basal-, HER2-, and luminal subtypes were carried out. We set out to assess the predictive value of Mammaprint scores (poor vs. good), as well as basal, vs. luminal, vs. HER2 molecular subtype profiling, for response to treatment on arms A vs. B vs. C. Responses were dichotomized as complete or near complete response (Symmans RCB scores of 0-1) vs. suboptimal response (RCB score &gt; 1). Results: Sufficient amount of BC tissue and good quality RNA for gene array assessment were procured in 64% of the first 90 patients who have undergone pre-treatment core biopsies, and then proceeded to NCT, followed by definitive surgery. Here we report on the first 50 pts with complete set of data analyzed. The median age was 50 years (range:31-69). Pts were treated for stage II (49%) and III locally advanced (41%), and inflammatory BC (10%). By gene profiling, 28% of the tumors were HER2-type (vs. 38% by IHC 3+, or FISH, representing all pts treated on arm C), 26% basal-type, 42% luminal-type, and 4% borderline luminal-type. Poor-prognosis signature by the 70-gene (MammaPrint) assay was observed in 74% of pts: 92% of HER2-type, 100% of basal-type, and 52% of luminal-type tumors were characterized as poor-risk by the 70-gene assay. Following NCT, Symmans RCB scores of 0-1 were observed in 71% of pts with HER2-type, in 38% with basal-type, and 28% of pts with luminal-type molecular subtype characteristics. Conclusion: BC with HER2- and basal-molecular subtypes are more likely to respond to NCT and is frequently associated with poor-risk characteristics as determined by the 70-gene assay. The complete analysis of correlations among response to specific sets of NCT, molecular subtype, and 70-gene assay results in the entire pt population will be presented.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2026.

Transcranial magnetic stimulation in ALS: utility of central motor conduction tests

OBJECTIVE

To investigate transcranial magnetic stimulation (TMS) measures as clinical correlates and longitudinal markers of amyotrophic lateral sclerosis (ALS).

METHODS

We prospectively studied 60 patients with ALS subtypes (sporadic ALS, familial ALS, progressive muscular atrophy, and primary lateral sclerosis) using single pulse TMS, recording from abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. We evaluated three measures: 1) TMS motor response threshold to the ADM, 2) central motor conduction time (CMCT), and 3) motor evoked potential amplitude (correcting for peripheral changes). Patients were evaluated at baseline, compared with controls, and followed every 3 months for up to six visits. Changes were analyzed using generalized estimation equations to test linear trends with time.

RESULTS

TMS threshold, CMCT, and TMS amplitude correlated (p < 0.05) with clinical upper motor neuron (UMN) signs at baseline and were different (p < 0.05) from normal controls in at least one response. Seventy-eight percent of patients with UMN (41/52) and 50% (4/8) of patients without clinical UMN signs had prolonged CMCT. All three measures revealed significant deterioration over time: TMS amplitude showed the greatest change, decreasing 8% per month; threshold increased 1.8% per month; and CMCT increased by 0.9% per month.

CONCLUSIONS

Transcranial magnetic stimulation (TMS) findings, particularly TMS amplitude, can objectively discriminate corticospinal tract involvement in amyotrophic lateral sclerosis (ALS) from controls and assess the progression of ALS. While central motor conduction time and response threshold worsen by less than 2% per month, TMS amplitude decrease averages 8% per month, and may be a useful objective marker of disease progression.

Drosophila homolog of APP-BP1 (dAPP-BP1) interacts antagonistically with APPL during Drosophila development

beta-Amyloid precursor protein binding protein 1 (APP-BP1) was previously identified based on its binding to the carboxyl terminal of beta-amyloid precursor protein. In this report, we have discovered that a mutation of dAPP-BP1 (Drosophila ortholog of APP-BP1) hinders tissue development, causes apoptosis in imaginal disc cells, and blocks the NEDD8 conjugation pathway. We show that dAPP-BP1 specifically binds the intracellular domain of APP-like protein (APPL). The dAPP-BP1 mutation partially suppresses the abnormal macrochaete phenotype of Appl(d), while overexpression of dAPP-BP1 causes abnormal macrochaetes. When APPL is overexpressed, the normal bristle pattern in the fly thorax is disturbed and apoptosis is induced in wing imaginal discs. APPL overexpression phenotypes are enhanced by reducing the level of dAPP-BP1. APPL overexpression is shown to inhibit the NEDD8 conjugation pathway. APPL-induced apoptosis is rescued by overexpression of dAPP-BP1. Our data suggest that APPL and dAPP-BP1 interact antagonistically during Drosophila development.

Expression of the seqA gene is negatively modulated by the HU protein in Escherichia coli

The SeqA protein acts as a regulator of chromosomal replication initiation in Escherichia coli by sequestering hemi-methylated oriC, effectively blocking methylation and therefore preventing rapid re-initiation. The level of SeqA protein is maximal at mid-log phase and decreases when cells enter late-log phase. In hup mutants that lack the HU protein, the maximal seqA expression is also seen at mid-log phase, but seqA expression, as well as SeqA levels and activity, is increased by up to four fold relative to that in the wild type. These results suggest that the HU protein functions as a negative modulator of seqA expression.

Molecular characterization of Drosophila melanogaster myo-inositol-1-phosphate synthase

We have isolated and characterized a cDNA encoding Drosophila melanogaster myo-inositol-1-phosphate synthase (INOS). The deduced Drosophila INOS protein is 50% identical to the Saccharomyces cerevisiae INO1 gene. The putative active site residues are well conserved in Drosophila INOS protein. Southern blot analysis shows that Drosophila INOS gene is a single copy gene. Northern blot analysis reveals that Drosophila INOS gene expresses a 2.0-kb transcript that is more abundant in the head than the body, suggesting that it may be involved in brain function. The recombinant Drosophila INOS protein was expressed in Escherichia coli and the purified protein has proved to have a myo-inositol-1-phosphate synthase activity.

5'-Flanking sequence and promoter activity of the rabbit neuronal nitric oxide synthase (nNOS) gene

We have isolated a rabbit neuronal nitric oxide synthase (nNOS) cDNA encoding a protein of 1,435 amino acids. Using the cDNA clones as probes, the 5'-flanking region of the nNOS gene was isolated from a rabbit genomic DNA library. 5'RACE and primer extension analysis of rabbit brain total RNA mapped multiple transcription initiation sites localized 474-487 bp upstream from the translation start codon. Analysis of 5,197 bp of the 5'-flanking sequence revealed that the rabbit nNOS gene promoter lacks canonical TATA or CCAAT boxes and, instead, contains a GC-rich region and multiple Sp1 sites. Farther from the +1start, various putative cis-elements including AP-1, AP-4, NF-kappaB, STAT, CREB, C/EBP and c-Myc were observed. The functional promoter activity of the 5'-flanking region was demonstrated by its ability to drive the expression of a beta-galactosidase reporter gene in several cell types. Serial deletion analysis of the promoter region revealed that the -291 to -172 region, which contains two Sp1 sites, is essential for basal transcriptional activity. These results suggest that the rabbit nNOS promoter contains characteristics of inducible genes.

Epithelial cell-specific laminin 5 is required for survival of early thymocytes

The gene LamC2 encoding the gamma2 chain of laminin 5, an epithelial cell-specific extracellular matrix protein, was identified in a PCR-based subtracted cDNA library from mouse thymic stromal cells. The mRNA existed in two alternative forms (5.1 and 2.4 kb). The full-length message was highly expressed in SCID thymus and in a nurse cell line, but not in other thymic epithelial cell lines, while the short form was more widely expressed. In situ hybridization and immunohistochemical staining revealed laminin 5 expression mostly in the subcapsular region of the adult thymus. Addition to fetal thymic organ cultures of a cell adhesion-blocking mAb to the alpha3 chain of laminin 5 interrupted T cell development. There was a 40% reduction in the total yield of thymocytes, and the most profound decrease (75-90%) was seen in the CD25+CD44+ and CD25+CD44-subsets of the CD4-CD8- double negative fraction. Most of the surviving double negative thymocytes expressed Sca-1, and there were significant increases in the number of cells with CD69 expression and in the fraction of annexin V-stained cells. None of these changes were observed with a nonblocking anti-laminin alpha3 chain mAb. These results suggest that the interaction between double negative thymoctyes and laminin 5 made by subcapsular epithelial cells is required for the survival and differentiation of mouse thymocytes.

Molecular characterization of Drosophila melanogaster dihydropteridine reductase

Dihydropteridine reductase (DHPR) catalyzes the NAD(P)H-mediated reduction of quinonoid dihydropteridine as a part of pterin-dependent aromatic amino acid hydroxylation. We isolated a fragment of Drosophila DHPR gene by PCR using degenerate primers. By screening a cDNA library, we obtained full-length clones. The predicted amino acid sequence of the Drosophila DHPR protein was highly homologous to other species including human and mouse. In particular, the Tyr-(Xaa)(3)-Lys motif, known as the NAD(P)H binding domain, and most amino acids relevant to quinonoid dihydropteridine binding site are identical to human DHPR. The recombinant DHPR protein expressed in Escherichia coli showed DHPR enzyme activity. Northern blot analysis revealed two transcripts of 1.1 and 0.9 kb. Genomic DNA sequencing revealed that the gene consists of two exons interrupted by a single 96-bp intron. The two transcripts have alternative promoters, both having no putative TATA box or CAAT box, but sharing a common poly(A)(+) signal. The existence of two alternative promoters suggests that each transcript be regulated independently through different stimuli. Further study is needed to examine the expression and function of the two alternative transcripts.

Signaling pathways to the assembly of an interferon-beta enhanceosome. Chemical genetic studies with a small molecule

Small molecules that modulate specific protein functions are valuable tools for dissecting complex signaling pathways. Here, we identified a small molecule that induces the assembly of the interferon-beta (IFN-beta) enhanceosome by stimulating all the enhancer-binding activator proteins: ATF2/c-JUN, IRF3, and p50/p65 of NF-kappaB. This compound stimulates mitogen-activated protein kinase kinase kinase 1 (MEKK1), which is a member of a family of proteins involved in stress-mediated signaling pathways. Consistent with this, MEKK1 activates IRF3 in addition to ATF2/c-JUN and NF-kappaB for the assembly of the IFN-beta enhanceosome. MEKK1 activates IRF3 through the c-JUN amino-terminal kinase (JNK) pathway but not the p38 and IkappaB kinase (IKK) pathway. Taken together with previous observations, these results implicate that, for the assembly of an IFN-beta enhanceosome, MEKK1 can induce IRF3 and ATF2/c-JUN through the JNK pathway, whereas it can induce NF-kappaB through the IKK pathway. Thus, specific MEKK family proteins may be able to integrate some of multiple signal transduction pathways leading to the specific activation of the IFN-beta enhanceosome.

Fringe forms a complex with Notch

The Fringe protein of Drosophila and its vertebrate homologues function in boundary determination during pattern formation. Fringe has been proposed to inhibit Serrate-Notch signalling but to potentiate Delta-Notch signalling. Here we show that Fringe and Notch form a complex through both the Lin-Notch repeats and the epidermal growth factor repeats 22-36 (EGF22-36) of Notch when they are co-expressed. The Abruptex59b (Ax59b) and AxM1 mutations, which are caused by missense mutations in EGF repeats 24 and 25, respectively, abolish the Fringe-Notch interaction through EGF22-36, whereas the l(1)N(B) mutation in the third Lin-Notch repeat of Notch abolishes the interaction through Lin-Notch repeats. Ax mutations also greatly affect the Notch response to ectopic Fringe in vivo. Results from in vitro protein mixing experiments and subcellular colocalization experiments indicate that the Fringe-Notch complex may form before their secretion. These findings explain how Fringe acts cell-autonomously to modulate the ligand preference of Notch and why the Fringe-Notch relationship is conserved between phyla and in the development of very diverse structures.

Identification of Mad as a repressor of the human telomerase (hTERT) gene

Activation of telomerase, which has been frequently associated with cellular immortality, may constitute a key step in the development of human cancer. De-repression in the expression of its catalytic subunit hTERT gene has been proposed to directly link to the telomerase activation in tumor cells. Little is known about the mechanism how the hTERT gene is repressed in telomerase-negative mortal cells. This study was conducted, using an expression cloning approach, with the aim of identifying the gene(s) responsible for repressing the hTERT gene expression. Using this genetic screen, we isolated the transcription factor Mad as a repressor. Mutation of its DNA binding sites caused significant de-repression of hTERT promoter activity in mortal cells. This Mad-mediated repression of the hTERT promoter in mortal cells was counteracted by ectopic expression of Myc. The antagonism between Mad and Myc was also observed with an endogenous hTERT promoter. Their potential roles in differential hTERT promoter activities were further supported by the relative amounts of Mad and Myc proteins detected in immortal and mortal cells. Thus, Mad may be a direct negative regulator of hTERT in mortal cells and this repression mechanism can be inhibited by induction of Myc in immortal cells.

Chemotherapeutic DNA-damaging drugs activate interferon regulatory factor-7 by the mitogen-activated protein kinase kinase-4-cJun NH2-terminal kinase pathway

Chemotherapeutic drugs and energy-rich radiation cause DNA damage, inducing signaling pathways for apoptotic cell death or cell growth arrest. The tumor suppressor gene p53 plays the critical role in the regulation of these DNA damage responses. Human tumor cells can become resistant to chemotherapy through functional inactivation of p53. Thus, it is important to identify p53-independent DNA damage signaling pathways. Here, treatment of cells with chemotherapeutic drugs or UV irradiation potentiated the transcriptional activity of IFN regulatory factor-7 (IRF7), inducing its phosphorylation and its nuclear translocation. Furthermore, IRF7 was activated by the c-Jun NH2-terminal kinase (JNK) in response to DNA-damaging agents. Activation of JNK by mitogen-activated protein kinase kinase-4 stimulated the transcriptional activity of IRF7 and induced its translocation into the nucleus. Thus, activation of IRF7 through the JNK signaling pathway may play a role in the transcriptional regulation of genes in response to DNA-damaging agents.

Involvement of retinoblastoma protein in p27Kip1-induced apoptosis

p27Kip1, a cyclin-dependent kinase (CDK) inhibitor, plays a critical role in cell cycle regulation. Expression of p27Kip1 is shown to increase during apoptosis in mammalian cells. Here, to directly address the role of p27Kip1 in apoptosis, p27Kip1 is overexpressed in human SK-Hep1 hepatoma cells. This leads to apoptotic cell death and this reduces protein, but not mRNA, levels of the retinoblastoma (Rb). Consistently, accumulation of Rb protein blocks p27Kip1-mediated apoptosis. These studies demonstrate an involvement of Rb in the apoptotic cell death which is induced by overexpression of p27Kip1.