bluuebunny/crossref_metadata_2025 huggingface dataset:
Transforming Acidic Coiled Coil 1 Promotes Transformation and Mammary Tumorigenesis
Authors: Cully Megan , Shiu Jessica , Piekorz Roland P. , Muller William J. , Done Susan J. , Mak Tak W.
Published: November 2005

Transforming acidic coiled coil 1 (TACC1) is a putative oncogene located within a breast cancer amplicon found on human chromosome 8p11. Although TACC1 has been reported to transform fibroblasts, it is also down-regulated in a subset of mammary tumors treated with anthracyclin. Here, we show that ectopic TACC1 overexpression can cooperate with Ras to induce focus formation in murine fibroblast cultures and prevent death caused by overexpression of Pten or a dominant-negative form of protein kinase B (PKB)/Akt. In transgenic mice carrying TACC1 under the control of the mouse mammary tumor virus promoter, TACC1 expression reduced apoptosis during mammary gland involution, increased the penetrance of mammary tumors in a pten+/− background, and decreased the average age of mammary tumor onset in a mouse model based on a phosphatidylinositol 3′-kinase (PI3K)–decoupled mutant of polyoma middle T. Elevated levels of both phospho-PKB and phospho-extracellular signal-regulated kinase were found in mammary tissue containing the TACC1 transgene. Thus, TACC1 positively regulates the Ras and PI3K pathways, promotes Ras-mediated transformation, and prevents apoptosis induced by PI3K pathway inhibition. TACC1 also cooperates with tumorigenic mutations in the PI3K pathway and thereby plays an oncogenic role in tumor formation in the murine mammary gland.
Abrogation of Heat Shock Protein 70 Induction as a Strategy to Increase Antileukemia Activity of Heat Shock Protein 90 Inhibitor 17-Allylamino-Demethoxy Geldanamycin
Authors: Guo Fei , Rocha Kathy , Bali Purva , Pranpat Michael , Fiskus Warren , Boyapalle Sandhya , Kumaraswamy Sandhya , Balasis Maria , Greedy Benjamin , Armitage E. Simon M. , Lawrence Nicholas , Bhalla Kapil
Published: November 2005

17-Allylamino-demethoxy geldanamycin (17-AAG) inhibits the chaperone association of heat shock protein 90 (hsp90) with the heat shock factor-1 (HSF-1), which induces the mRNA and protein levels of hsp70. Increased hsp70 levels inhibit death receptor and mitochondria-initiated signaling for apoptosis. Here, we show that ectopic overexpression of hsp70 in human acute myelogenous leukemia HL-60 cells (HL-60/hsp70) and high endogenous hsp70 levels in Bcr-Abl-expressing cultured CML-BC K562 cells confers resistance to 17-AAG-induced apoptosis. In HL-60/hsp70 cells, hsp70 was bound to Bax, inhibited 17-AAG-mediated Bax conformation change and mitochondrial localization, thereby inhibiting the mitochondria-initiated events of apoptosis. Treatment with 17-AAG attenuated the levels of phospho-AKT, AKT, and c-Raf but increased hsp70 levels to a similar extent in the control HL-60/Neo and HL-60/hsp70 cells. Pretreatment with 17-AAG, which induced hsp70, inhibited 1-β-d-arabinofuranosylcytosine or etoposide-induced apoptosis in HL-60 cells. Stable transfection of a small interfering RNA (siRNA) to hsp70 completely abrogated the endogenous levels of hsp70 and blocked 17-AAG-mediated hsp70 induction, resulting in sensitizing K562/siRNA-hsp70 cells to 17-AAG-induced apoptosis. This was associated with decreased binding of Bax to hsp70 and increased 17-AAG-induced Bax conformation change. 17-AAG-mediated decline in the levels of AKT, c-Raf, and Bcr-Abl was similar in K562 and K562/siRNA-hsp70 cells. Cotreatment with KNK437, a benzylidine lactam inhibitor of hsp70 induction and thermotolerance, attenuated 17-AAG-mediated hsp70 induction and increased 17-AAG-induced apoptosis and loss of clonogenic survival of HL-60 cells. Collectively, these data indicate that induction of hsp70 attenuates the apoptotic effects of 17-AAG, and abrogation of hsp70 induction significantly enhances the antileukemia activity of 17-AAG.
Src Tyrosine Kinase and Multidrug Resistance Protein-1 Inhibitions Act Independently but Cooperatively to Restore Paclitaxel Sensitivity to Paclitaxel-Resistant Ovarian Cancer Cells
Authors: George Jessica A. , Chen Ting , Taylor Christopher C.
Published: November 2005

Src tyrosine kinase has been found to be overexpressed in both mouse and human ovarian cancer cells as well as in human primary ovarian cancers. Furthermore, Src inhibition sensitizes ovarian cancer cells to chemotherapeutic agents such as paclitaxel and cisplatin. Interestingly, Src inhibition has also been shown to resensitize paclitaxel-resistant cells to the cytotoxic effects of paclitaxel. The current study was undertaken in an effort to determine the mechanism by which Src resensitizes drug-resistant ovarian cancer cells. The paclitaxel-resistant human (CaOV3TaxR) and mouse (ID8TaxR) ovarian cancer cell lines express large amounts of the multidrug resistance-1 (MDR-1) protein compared with the paclitaxel-sensitive parent cell lines. Src inhibition had no effect on MDR-1 protein expression. Furthermore, Src inhibition did not affect MDR-1 function as determined by rhodamine 123 and paclitaxel uptake or retention. Coinhibition of both Src and MDR-1 synergistically enhanced paclitaxel-induced cytotoxicity in paclitaxel-resistant ovarian cancer cell lines. Inhibition of Src enhanced microtubule stabilization in paclitaxel-resistant ovarian cancer cells treated with paclitaxel without affecting expression of β-tubulin isotypes and resulted in multipolar spindle formation and apoptosis. These results show that Src inhibition restores paclitaxel sensitivity to paclitaxel-resistant ovarian cancer cells by an MDR-independent mechanism, possibly by decreasing the critical intracellular concentration at which paclitaxel induces tubulin stabilization and bundling. Src tyrosine kinase may provide a viable target for therapeutic intervention in drug-resistant ovarian cancer.
Orthotopic Growth of Human Glioma Cells Quantitatively and Qualitatively Influences Radiation-Induced Changes in Gene Expression
Authors: Camphausen Kevin , Purow Benjamin , Sproull Mary , Scott Tamalee , Ozawa Tomoko , Deen Dennis F. , Tofilon Philip J.
Published: November 2005

The effect of radiation on gene expression has been most frequently studied using tissue culture models. To determine the influence of experimental growth condition on radiation-induced changes in gene expression, microarray analysis was done on two human glioma cell lines (U87 and U251) grown in tissue culture and as s.c. or i.c. xenografts. Compared with tissue culture, the number of genes, whose expression was affected by radiation in both cell lines, was increased in the s.c. xenografts and further increased in the orthotopic tumors. Furthermore, in each growth condition, radiation modulated the expression of a different set of genes. In addition, whereas there were few commonly affected genes after irradiation of U87 and U251 in tissue culture, there were 729 common changes after orthotopic irradiation. These results indicate that the influence of the orthotopic environment on radiation-induced modulation of gene expression in glioma cells was both quantitative and qualitative. Moreover, they suggest that investigations of the functional consequence of radiation-induced gene expression will require accounting for experimental growth conditions.
Cancer-Specific Functions of SIRT1 Enable Human Epithelial Cancer Cell Growth and Survival
Authors: Ford Jack , Jiang Ming , Milner Jo
Published: November 2005

SIRT1 is a conserved NAD-dependent deacetylase that regulates life span in accord with nutritional provision. In mammalian cells, SIRT1 also down-regulates stress-induced p53 and FoxO pathways for apoptosis, thus favoring survival under stress. The functioning of SIRT1 under normal, nonstressed conditions of cell growth is unknown. Here we have asked if SIRT1 has the capacity to influence cell viability in the absence of applied stress. For this purpose we used synthetic small interfering RNA to silence SIRT1 gene expression by RNA interference (RNAi). We show that the process of RNAi, by itself, does not affect cell growth and is not sufficient to activate a cellular stress response (indicated by lack of activation of endogenous p53). We also show that, in the absence of applied stress, SIRT1 silencing induces growth arrest and/or apoptosis in human epithelial cancer cells. In contrast, normal human epithelial cells and normal human diploid fibroblasts seem to be refractory to SIRT1 silencing. Combined gene knockout with RNAi cosilencing experiments indicate that SIRT1 and Bcl-2 may suppress separable apoptotic pathways in the same cell lineage and that the SIRT1-regulated pathway is independent of p53, Bax, and caspase-2. Alternatively, SIRT1 may suppress apoptosis downstream from these apoptotic factors. In either case, we show that FoxO4 (but not FoxO3) is required as proapoptotic mediator. We further identify caspase-3 and caspase-7 as downstream executioners of SIRT1/FoxO4–regulated apoptosis. Our work identifies SIRT1 as a novel target for selective killing of cancer versus noncancer epithelial cells.
Inhibition of Intestinal Tumorigenesis in Apcmin/+ Mice by (−)-Epigallocatechin-3-Gallate, the Major Catechin in Green Tea
Authors: Ju Jihyeung , Hong Jungil , Zhou Jian-nian , Pan Zui , Bose Mousumi , Liao Jie , Yang Guang-yu , Liu Ying Ying , Hou Zhe , Lin Yong , Ma Jianjie , Shih Weichung Joe , Carothers Adelaide M. , Yang Chung S.
Published: November 2005

The present study was designed to investigate the effects of two main constituents of green tea, (−)-epigallocatechin-3-gallate (EGCG) and caffeine, on intestinal tumorigenesis in Apcmin/+ mice, a recognized mouse model for human intestinal cancer, and to elucidate possible mechanisms involved in the inhibitory action of the active constituent. We found that p.o. administration of EGCG at doses of 0.08% or 0.16% in drinking fluid significantly decreased small intestinal tumor formation by 37% or 47%, respectively, whereas caffeine at a dose of 0.044% in drinking fluid had no inhibitory activity against intestinal tumorigenesis. In another experiment, small intestinal tumorigenesis was inhibited in a dose-dependent manner by p.o. administration of EGCG in a dose range of 0.02% to 0.32%. P.o. administration of EGCG resulted in increased levels of E-cadherin and decreased levels of nuclear β-catenin, c-Myc, phospho-Akt, and phospho-extracellular signal–regulated kinase 1/2 (ERK1/2) in small intestinal tumors. Treatment of HT29 human colon cancer cells with EGCG (12.5 or 20 μmol/L at different times) also increased protein levels of E-cadherin by 27% to 58%, induced the translocation of β-catenin from nucleus to cytoplasm and plasma membrane, and decreased c-Myc and cyclin D1 (20 μmol/L EGCG for 24 hours). These results indicate that EGCG effectively inhibited intestinal tumorigenesis in Apcmin/+ mice, possibly through the attenuation of the carcinogenic events, which include aberrant nuclear β-catenin and activated Akt and ERK signaling.
Control of Multidrug Resistance Gene mdr1 and Cancer Resistance to Chemotherapy by the Longevity Gene sirt1
Authors: Chu Fei , Chou Pauline M. , Zheng Xin , Mirkin Bernard L. , Rebbaa Abdelhadi
Published: November 2005

Irreversible growth arrest (also called senescence) has emerged recently as a tumor suppressor mechanism and a key determinant of cancer chemotherapy outcome. Previous work from our laboratory suggested that the cellular ability to undergo or to escape senescence dictates its fate to become drug-sensitive or drug-resistant, respectively. In the present study, we made the hypothesis that longevity genes, by virtue of their ability to inhibit senescence, may contribute to the onset of drug resistance. We report that expression of the longevity gene sirt1 increased both at the RNA and protein levels in all the five drug-resistant cell lines tested when compared with their drug-sensitive counterparts. In addition, biopsies from cancer patients treated with chemotherapeutic agents also expressed high levels of this molecule. These changes were specific for sirt1 because the expression of other members of its family was not affected. More importantly, small interfering RNA–mediated down-regulation of sirt1 significantly reversed the resistance phenotype and reduced expression of the multidrug resistance molecule P-glycoprotein. This was further confirmed by ectopic overexpression of sirt1, which induced expression of P-glycoprotein and rendered cells resistant to doxorubicin. Collectively, these findings uncovered a novel function for the longevity gene sirt1 as a potential target for diagnosis and/or treatment of cancer resistance to chemotherapy. They also describe a proof of principle that signaling pathways implicated in longevity may share similarities with those leading to development of drug resistance in cancer.
Extremely Low Dose Ionizing Radiation Up-regulates CXC Chemokines in Normal Human Fibroblasts
Authors: Fujimori Akira , Okayasu Ryuichi , Ishihara Hiroshi , Yoshida Satoshi , Eguchi-Kasai Kiyomi , Nojima Kumie , Ebisawa Satoru , Takahashi Sentaro
Published: November 2005

Although the public today could be exposed to X-rays as high as 1 cGy due to diagnostic procedures, the biological effects of this low-dose range have not been well established. We searched through >23,000 transcripts in normal human fibroblasts, HFLIII, using a novel comprehensive expression analysis method. More than 200 genes were up-regulated transiently by 1 cGy of X-rays during the 1-hour period after irradiation. We determined the nucleotide sequence of 10 up-regulated transcripts with the greatest rate of increase in the irradiated HFLIII cells. Three of the 10 transcripts encoded CXC chemokines (CXCL1, CXCL2, and CXCL6). The rest included the transcripts of other secretory products (secretogranin II, thrombospondin type I domain containing 2, amphiregulin, and interleukin-6) and unknown genes. To test the involvement of CXC chemokines in cells irradiated with low doses, we irradiated HFLIII cells with 1 to 20 cGy X-rays and transferred the media from HFLIII culture to two melanoma cell lines characteristic of excessive numbers of the CXC chemokine-specific receptors. The growth of these melanoma lines were significantly stimulated by the medium from HFLIII irradiated at 1 to 5 cGy. Our results indicate that human cells respond to doses of radiation as low as 1 cGy, and mechanisms alternative to those involved in moderate/high-dose studies have to be considered in understanding the biological effects of diagnostic level radiation. In addition, our comprehensive approach using a novel expression profiling method is a powerful strategy to explore biological functions associated with very low levels of toxic agents.
Destabilization of Krüppel-Like Factor 4 Protein in Response to Serum Stimulation Involves the Ubiquitin-Proteasome Pathway
Authors: Chen Zhi Yi , Wang Xuesheng , Zhou Yunhong , Offner Gwynneth , Tseng Chi-Chuan
Published: November 2005

Although the zinc finger transcription factor Krüppel-like factor 4 (KLF4) has been shown to be a negative regulator of cell proliferation, the mechanisms underlying the posttranslational modification of KLF4, especially at the level of protein degradation, are poorly understood. Here, we show that KLF4 protein levels in quiescent cells were high, but decreased rapidly as cells entered the proliferating stage following serum stimulation. This decrease was partially reversed by pretreatment with MG132, a proteasome inhibitor. Moreover, KLF4 was an unstable protein that underwent rapid turnover, and exhibited a relatively short half-life (t1/2 ∼120 minutes). To investigate the involvement of the ubiquitin-proteasome pathway in the regulation of the stability of KLF4, HCT116 cells were treated with proteasome inhibitors. Our results showed that, following lactacystin treatment, levels of endogenous KLF4 increased in a time- and dose-dependent manners. Using a cell-free system, in vitro–translated 35S-labeled KLF4 protein was degraded by protein extracts prepared from exponentially growing HCT116 cells in the presence of ATP. These effects were prevented by pretreatment with MG132 or replacement of ATP with ATP-γ-S, a nonhydrolyzable analogue of ATP, suggesting that ATP is required for KLF4 degradation by the 26S proteasome. In addition, KLF4 was subject to ubiquitination when cells were treated with the proteasome inhibitor or transfected with exogenous ubiquitin. Collectively, these results indicate that destabilization of KLF4 following serum stimulation is mediated, at least in part, through a ubiquitin-proteasome pathway.
A Novel RING-Type Ubiquitin Ligase Breast Cancer-Associated Gene 2 Correlates with Outcome in Invasive Breast Cancer
Authors: Burger Angelika M. , Gao Yuguang , Amemiya Yutaka , Kahn Harriette J. , Kitching Richard , Yang Yili , Sun Ping , Narod Steven A. , Hanna Wedad M. , Seth Arun K.
Published: November 2005

The RING finger family of proteins possess ubiquitin ligase activity and play pivotal roles in protein degradation and receptor-mediated endocytosis. In this study, we examined whether the breast cancer-associated gene 2 (BCA2), a novel RING domain protein, has E3 ubiquitin ligase activity and investigated its expression status in breast tumors. The full-length BCA2 gene was cloned from the human breast cancer cell line MDA-MB-468. It encodes an open reading frame of 304 amino acids and contains a RING-H2 domain. BCA2 maps to chromosome 1q21.1, a region known to harbor cytogenetic aberrations in breast cancers. We found that the BCA2 protein has an intrinsic autoubiquitination activity, the hallmark of E3 ligases, whereas mutant RING protein is not autoubiquitinated. This indicates that the BCA2 ubiquitin ligase activity is dependent on the RING-H2 domain. Using tissue microarrays and immunohistochemistry, we found strong to intermediate BCA2 staining in 56% of 945 invasive breast cancers cases, which was significantly correlated with positive estrogen receptor status [odds ratio (OR), 1.51; P = 0.004], negative lymph node status (OR, 0.73; P = 0.02), and an increase in disease-free survival for regional recurrence (OR, 0.45; P = 0.03). Overexpression of BCA2 increased proliferation and small interfering RNA inhibited growth of T47D human breast cancer cells and NIH3T3 mouse cells. The autoubiquitination activity of BCA2 indicates that it is a novel RING-type E3 ligase. Its association with clinical measures and its effects on cell growth indicate that BCA2 may be important for the ubiquitin modification of proteins crucial to breast carcinogenesis and growth.
Interleukin-7-Dependent Expansion and Persistence of Melanoma-Specific T Cells in Lymphodepleted Mice Lead to Tumor Regression and Editing
Authors: Wang Li-Xin , Li Rui , Yang Guojun , Lim May , O'Hara Aisling , Chu Yiwei , Fox Bernard A. , Restifo Nicholas P. , Urba Walter J. , Hu Hong-Ming
Published: November 2005

Active-specific immunotherapy with dendritic cells loaded with peptide derived from the melanoma antigen, gp100, failed to mediate regression of established B16F10 melanoma in normal mice. Dendritic cell vaccination induced activation and subsequent deletion of adoptively transferred naive CD8+ T-cell receptor transgenic (pmel-1) T cells specific for gp100 in normal mice. In lymphodepleted mice, dendritic cell vaccination produced greater T-cell expansion, long-term persistence of memory T cells, and tumor regression. Most tumors that persisted in the presence of functional memory T cells had either lost or exhibited reduced expression of MHC class I or gp100 proteins. In contrast to other naive T cells, pmel-1 T cells adoptively transferred to lymphodepleted mice exhibited faster proliferation and a more differentiated phenotype after exposure to peptide-pulsed dendritic cells. Proliferation and persistence of pmel-1 T cells was highly dependent on interleukin-7 (IL-7) in irradiated mice, and IL-15 when IL-7 was neutralized, two critical homeostatic cytokines produced in response to the irradiation-induced lymphodepletion.
Reliable High-Throughput Genotyping and Loss-of-Heterozygosity Detection in Formalin-Fixed, Paraffin-Embedded Tumors Using Single Nucleotide Polymorphism Arrays
Authors: Lips Esther H. , Dierssen Jan Willem F. , van Eijk Ronald , Oosting Jan , Eilers Paul H.C. , Tollenaar Rob A.E.M. , de Graaf Eelco J. , van't Slot Ruben , Wijmenga Cisca , Morreau Hans , van Wezel Tom
Published: November 2005

Most human cancers show genetic instabilities leading to allelic imbalances, including loss of heterozygosity (LOH). Single nucleotide polymorphism (SNP) arrays can be used to detect LOH. Currently, these arrays require intact genomic DNA as obtained from frozen tissue; however, for most cancer cases, only low-quality DNA from formalin-fixed, paraffin-embedded (FFPE) tissue is available. In this study, we tested Illumina BeadArrays to genotype FFPE tissue and detect LOH/allelic imbalances in matched colorectal tumor and normal tissue. Genotypes were compared between leukocyte and FFPE normal tissue as well as between frozen and FFPE tumor tissue. Identical genotypes and LOH profiles were obtained from normal and tumor isolates. LOH was mainly observed on chromosomes 4, 5q, 12q, 14q, 15q, 17p, 18, and 20p, which are commonly detected regions in colorectal cancer. LOH profiles of the BeadArrays were compared with profiles obtained by Affymetrix GeneChip 10K arrays, showing identical LOH patterns. These data show that genome-wide genotyping of FFPE tissue with the BeadArray gives reliable results and is a powerful technique for LOH analysis.
Cyclin-Dependent Kinase 4 Expression Is Essential for Neu-Induced Breast Tumorigenesis
Authors: Reddy Haritha K.D.L. , Mettus Richard V. , Rane Sushil G. , Graña Xavier , Litvin Judith , Reddy E. Premkumar
Published: November 2005

Previous work has shown that cyclin D1 expression is required for neu- and ras-induced, but not wnt- or c-myc–induced, breast tumorigenesis in mice. Although cyclin D1 binds and activates cyclin-dependent kinase 4 (Cdk4), thereby mediating activation of a program of E2F-dependent gene expression, it has been suggested that the oncogenic activities of cyclin D1 are independent of Cdk4. To determine whether Cdk4 expression is required for breast tumorigenesis in mice, we have generated compound mice ectopically expressing the neu or wnt oncogenes in the mammary glands of wild-type and Cdk4−/− mice. Our results show that Cdk4 expression is required for efficient neu-induced tumorigenesis but is dispensable for wnt-induced breast tumorigenesis. In contrast to results previously observed in the mammary glands of cyclin D1−/− virgin females, our results show defects in mammary gland development in Cdk4−/− virgin females, suggesting differences in compensatory mechanisms in the absence of either subunit of the cyclin D1/Cdk4 complex. These results suggest that drugs targeted to inhibit Cdk4 activities could be developed to specifically treat certain breast tumors as Cdk4 is not essential for viability.
Is mda-7/IL-24 a “Magic Bullet” for Cancer?
Authors: Fisher Paul B.
Published: November 2005

The “holy grail” of cancer therapy is to identify and exploit genetic elements and signal transduction pathways capable of selectively destroying tumor cells without eliciting harmful effects in normal cells or tissues. To achieve this objective, subtraction hybridization was combined with a “differentiation therapy” model of cancer in which human melanoma cells were induced to revert to a more “normal” state, growth arrest irreversibly, and terminally differentiate by treatment with fibroblast IFN and mezerein. This strategy permitted the cloning of a variety of genes involved in regulating important physiologic processes, including cell cycle, response to cytokines and viruses, tumorigenesis and metastasis, cancer growth control, apoptosis, and senescence. A specific gene, melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24), displaying cancer-specific apoptosis-inducing properties isolated using this scheme has now come into the limelight as a new gene therapy for divergent cancers. Although the mechanism of cancer cell selectivity of mda-7/IL-24 remains to be delineated, numerous attributes enable this gene as an effective therapy for cancer, including an ability to discriminate between normal and cancer cells, induce apoptosis in diverse tumor cells, promote “bystander” antitumor effects, inhibit tumor growth and angiogenesis in animal models, synergize with radiation, and modulate immune responses. These unique features combined with successful transition into the clinic instill confidence that mda-7/IL-24, as a single or more likely as part of a combinatorial approach, may provide profound therapeutic benefit for cancer patients.
Disruption of Protein Kinase A Regulation Causes Immortalization and Dysregulation of D-Type Cyclins
Authors: Nadella Kiran S. , Kirschner Lawrence S.
Published: November 2005

Phosphorylation is a key event in cell cycle control, and dysregulation of this process is observed in many tumors, including those associated with specific inherited neoplasia syndromes. We have shown previously that patients with the autosomal dominant tumor predisposition Carney complex carry inactivating mutations in the PRKAR1A gene, which encodes the type 1A regulatory subunit of protein kinase A (PKA), the cyclic AMP–dependent protein kinase. This defect was associated with dysregulation of PKA signaling, and genetic analysis has suggested that complete loss of the gene may be required for tumorigenesis. To determine the mechanism by which dysregulation of PKA causes tumor formation, we generated in vitro primary mouse cells lacking the Prkar1a protein. We report that this genetic disruption of PKA regulation causes constitutive PKA activation and immortalization of primary mouse embryonic fibroblasts (MEFs). At the molecular level, knockout of Prkar1a leads to up-regulation of D-type cyclins, and this increase occurs independently of other pathways known to increase cyclin D levels. Despite the immortalized phenotype, known mediators of cellular senescence (e.g., p53 and p19ARF) seem to remain intact in Prkar1a−/− MEFs. Mechanistically, cyclin D1 mRNA levels are not altered in the knockout cells, but protein half-life is markedly increased. Using this model, we provide the first direct genetic evidence that dysregulation of PKA promotes important steps in tumorigenesis, and that cyclin D1 is an essential target of PKA.
How Robust Are Laboratory Measures of Growth Hormone Status?
Authors: Strasburger Christian J. , Bidlingmaier Martin
Published: November 2005

Biochemical assessment of growth hormone (GH) status is required in both suspected GH deficiency and GH excess. GH secretion can either be measured through investigation of the pituitary or by monitoring markers that change as a consequence of GH action on its target tissues. The two most widely used and, to date, best validated biochemical parameters are immunoassay measurement of either human GH (hGH) or insulin-like growth factor (IGF)-I. The fundamental difference between measurement of hGH and IGF-I is that the first reflects GH secretion while the second reflects GH action. However, because GH secretion is pulsatile in nature, random blood sampling for determination of hGH levels is only minimally informative. Analytical methods for measuring GH and IGF-I show considerable between-method variability. Since these parameters are used in establishing diagnoses and in monitoring GH-related diseases, the endocrinologist should be aware of the specifications and limitations of the analytical methods available.
A Nationwide Attempt to Standardize Growth Hormone Assays
Authors: Tanaka Toshiaki , Tachibana Katsuhiko , Shimatsu Akira , Katsumata Noriyuki , Tsushima Toshio , Hizuka Naomi , Fujieda Kenji , Yokoya Susumu , Irie Minoru
Published: November 2005

The Growth Hormone (GH) and Its Related Factors Study Committee of the Foundation for Growth Science, Japan, has been conducting a quality control study for 15 years to improve the equality of diagnosis of GH deficiency. It found that the greatest differences in measured GH values were due to the different potencies of the kit standards, which were primarily adjusted to WHO standards for human GH of pituitary origin. With the collaboration of kit makers and the Study Group of Hypothalamo-Pituitary Disorders of the Ministry of Health, Labor and Welfare, all GH kits in Japan have begun using the same recombinant human GH standard since April 2005. As a result the diagnostic cut-off peak GH has changed from 10 to 6 ng/ml.
The Phenotype of Adults with Partial Growth Hormone Deficiency
Authors: Murray Robert D.
Published: November 2005

The concept of partial growth hormone (GH) deficiency (GHD) is well established within the paediatric setting having been validated against height velocity. In hypopituitary adults, GHD is defined by a peak GH response <3 µg/l to stimulation. This cut-off is arbitrary due to the lack of a biological marker equivalent of height velocity. The majority of normal adults achieve peak GH levels several fold higher than this cut off during stimulation. It can be argued, therefore, that there is a cohort of hypopituitary adults with intermediate peak GH values (3–7 µg/l), who have relatively impaired GH secretion, and for whom the impact of this partial GHD (GH insufficiency, GHI) on biological endpoints is not known. Studies of GHI adults have demonstrated an abnormal body composition, adverse lipid profile, impaired cardiac performance, reduced exercise tolerance and insulin resistance. The severity of these abnormalities lies between GHD adults and normal subjects. Whether these anomalies translate into increased mortality, as observed in GHD hypopituitary adults, is not yet known. Given the presence of similar sequelae in GHI and GHD adults, and the improvements during GH replacement in GHD adults, a randomized placebo-controlled study of GH replacement in GHI patients is warranted.
Does Surgical Genitoplasty Affect Gender Identity in the Intersex Infant?
Authors: Nihoul-Fékété C.
Published: November 2005

There is no clear-cut answer to the question of whether surgical genitoplasty affects gender identity in the intersex infant. The debate centres around which is more important for the development of gender identity: the biological sex of a child or the sex in which a child is reared. We believe that the surgical achievement of a phenotype concordant with the sex of rearing is a tremendous help to the parents of an intersex infant. We do not consider that the ‘neutral’ upbringing of a child with ambiguous genitalia is a feasible option, first because of the parents’ distress which prevents them from raising their child normally and second because in most cultures around the world gender variants are not treated as equals. A neutral upbringing may induce psychosocial consequences that are more pernicious than carefully considered neonatal sex attribution and concordant surgical genitoplasty.
Psychological Long-Term Outcome in Intersex Conditions
Authors: Cohen-Kettenis Peggy
Published: November 2005

For decades, sex assignment in children with intersex conditions has depended more on surgical possibilities than on other criteria, since it was assumed that children are psychosexually neutral at birth. Adults with intersex conditions and professionals in the field have increasingly criticized this policy after the publication of studies suggesting that prenatal brain exposure to sex hormones determines gender development. Although prenatal brain exposure to androgens plays some part in the development of gender role behaviour, the current evidence is not in line with the idea of determination of gender identity through prenatal sex steroid exposure. Recent reviews on gender dysphoria and gender change in patients with intersex conditions show that initial gender assignment still seems to be the best predictor of adult gender identity.
Sex Steroids and the Growth Hormone/Insulin-Like Growth Factor-I Axis in Adults
Authors: Jørgensen Jens O.L. , Christensen Jens Juel , Vestergaard Esben , Fisker Sanne , Ovesen Per , Christiansen Jens Sandahl
Published: November 2005

In healthy adults insulin-like growth factor (IGF)-I levels do not differ between males and females, whereas spontaneous growth hormone (GH) secretion is approximately twofold higher in females. Untreated GH-deficient (GHD) women exhibit lower IGF-I levels compared with men and the increase in serum IGF-I during GH replacement is also significantly less. These data suggest a resistance to GH in women, which in healthy subjects is compensated for by increased GH secretion. Administration of oral oestrogen in healthy postmenopausal women suppresses hepatic IGF-I production and increases pituitary GH release, and oral oestrogen replacement in women with GHD lowers IGF-I concentrations and increases the amount of GH necessary to achieve IGF-I target levels during treatment. These data clearly suggest that hepatic suppression of IGF-I production by oestrogen subserves the gender difference in GH sensitivity, but it is also likely that sex steroids may interact with the GH/IGF axis at other levels. There is also circumstantial evidence to indicate that testosterone stimulates IGF-I production and it is speculated that a certain threshold level of androgens is essential to ensure hepatic IGF-I production. Whether these data should translate into earlier discontinuation of oestrogen replacement therapy in women with hypopituitarism merits consideration.
Early Onset of Puberty: Tracking Genetic and Environmental Factors
Authors: Parent Anne-Simone , Rasier Gregory , Gerard Arlette , Heger Sabine , Roth Christian , Mastronardi Claudio , Jung Heike , Ojeda Sergio R. , Bourguignon Jean-Pierre
Published: November 2005

Under physiological conditions, factors affecting the genetic control of hypothalamic functions are predominant in determining the individual variations in timing of pubertal onset. In pathological conditions, however, these variations can involve different genetic susceptibility and the interaction of environmental factors. The high incidence of precocious puberty in foreign children migrating to Belgium and the detection in their plasma of a long-lasting 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) residue suggest the potential role of environmental endocrine disrupting chemicals in the early onset of puberty. This hypothesis was confirmed by experimental data showing that temporary exposure of immature female rats to DDT in vivo results in early onset of puberty. We compared the gene expression profile of hypothalamic hamartoma associated or not with precocious puberty in order to identify gene networks responsible for both hamartoma-dependent sexual precocity and the onset of normal human puberty. In conclusion, pathological variations in the timing of puberty may provide unique information about the interactions of either environmental conditions or genetic susceptibility with the hypothalamic mechanism controlling the onset of sexual maturation, as shown by examples of precocious puberty following exposure to endocrine disrupters or due to hypothalamic hamartoma.
Treatment of Short Children Born Small for Gestational Age: US Perspective, 2005
Authors: Chernausek Steven D.
Published: November 2005

Growth hormone (GH) administration to ameliorate growth deficiency of short children born small for gestational age (SGA) is currently approved in the US and the EU. Even though regulatory bodies from each examined similar datasets concerning GH treatment of short SGA children, the specifics of indications for treatment and recommended regimens differed with respect to GH dosage, age at which therapy might be initiated, and the degree of short stature required. US product labeling allows more flexibility but provides less guidance for the practitioner. The EU tends to be more proscriptive, limiting use to shorter children, restricting the dosage, and providing specific guidelines in terms of monitoring during treatment.
Timing and Type of Glucocorticoid Replacement in Adult Congenital Adrenal Hyperplasia
Authors: Ross R.J.M. , Rostami-Hodjegan A.
Published: November 2005

Congenital adrenal hyperplasia (CAH) is one of the commonest inherited diseases. Treatment during childhood is directed towards obtaining normal growth. There is an extensive literature on management of CAH during childhood but little published on how patients should be treated as adults. CAH results in increased adrenocorticotropic hormone levels driving the adrenal to produce cortisol and thereby excessive cortisol precursors which are predominantly androgenic. In normal individuals there is a marked circadian rhythm in cortisol release with the lowest levels occurring shortly after midnight and rising between 02.00 and 03.00 h to peak at around 06.00–08.00 h after waking. The treatment of choice for children with CAH is hydrocortisone three times daily. There is no consensus on treating adults. A recent survey by the UK Society for Endocrinology showed that hydrocortisone was the most popular steroid, followed by dexamethasone and then prednisolone. Sixty percent of respondents used a reverse circadian pattern of glucocorticoid treatment and only 16% used a dose based on weight or surface area. In a recent study we demonstrated that the most important variable determining hydrocortisone bioavailability is weight and we advocated a weight-related dosing regimen monitored using a nomogram for serum cortisol.
Congenital Adrenal Hyperplasia in Adulthood: Do Men Need to Continue Treatment?
Authors: Mönig Heiner , Sippell Wolfgang
Published: November 2005

Due to early diagnosis and appropriate paediatric treatment, internists and endocrinologists are now caring for an increasing number of adult patients with congenital adrenal hyperplasia (CAH). Problems that may be encountered in adult males with CAH are the continuing risk of developing an adrenal crisis and impaired gonadal function due to suppression of the hypothalamic-gonadal axis. Fertility may be further compromised by testicular adrenal rest tumours. Available data suggest that the reversal of infertility is more difficult once testicular nodules have developed. Similar to female CAH patients, male patients may develop adrenal tumours due to inadequate adrenocorticotropic hormone suppression. We therefore recommend continuous treatment of male CAH patients with careful monitoring of clinical and hormonal parameters in order to avoid overtreatment.
Difficulties in Patient Management Associated with the Transition Period
Authors: Clayton Peter E. , Shalet Stephen M.
Published: November 2005

The European Society for Paediatric Endocrinology (ESPE) held a consensus workshop in Manchester, UK, in December 2003 to discuss issues relating to the care of growth hormone (GH)-treated patients in the transition from paediatric to adult life [1]. Aspects under consideration included the definition of transition, the process of delivery of transitional care, the exact need to reassess pituitary status after completion of growth and puberty in teenagers who have received GH treatment during childhood, the most appropriate biochemical definition of severe GH deficiency (GHD) in the transitional period, and the factors influencing both the decision to reinstitute treatment and also the timing and dosage schedule when GH treatment is reinstituted.
The Role of Parathyroid Hormone in the Management of Osteoporosis
Authors: Rosen Clifford J.
Published: November 2005

It has been over 2 years since parathyroid hormone (PTH 1–34) was approved in the US and Europe for the treatment of osteoporosis in postmenopausal women and men. Clinical experience with this peptide has enhanced confidence in its use and its application in specific clinical scenarios. There is no doubt that PTH 1–34 is safe and effective in reducing spine and non-vertebral fractures in men and women. However, the lack of several randomized placebo-controlled trials and their relatively short duration raise several questions that still need to be answered. This paper reviews three major areas of uncertainty: (1) Is there significant heterogeneity in the bone density response of individuals to PTH? If so, what factors are important predictors? (2) What other regimens are available for PTH use? (3) What, if anything, should the clinician do after PTH is discontinued? Answers to these questions will undoubtedly lead to even greater utilization of this drug and some of its future derivatives.
Resurrections in Toronto: The Emergence of Insulin
Authors: Bliss Michael
Published: November 2005

The discovery of insulin remains the greatest and one of the most controversial events in the history of endocrinology. Hypotheses about the possible existence of an internal secretion of the pancreas date from the early 1890s and were steadily modified with the development of the concept of an endocrine system. In the spring of 1922, after many false starts and dead ends, a team of researchers at the University of Toronto provided conclusive evidence of the existence of the internal secretion of insulin. The discovery process was fraught with personal and scientific rivalries more striking than fiction. The early use of insulin on starved, dying diabetic children awed everyone involved in the process. With the discovery of insulin, endocrinology moved into the mainstream of medical science.
Investigation of the Safety of an Intraocular Lens with Reversibly Adjustable Optical Power: The *Acri.Tec AR-1 PC/IOL
Authors: Jahn Claus E. , Strotmann Heike
Published: November 2005

Purpose: To report the safety of a newly developed intraocular lens (PC/IOL) with reversibly adjustable refractive power (*Acri.Tec AR-1 PC/IOL) after implantation into adult human eyes. The surgical setup and specially designed instruments required for implantation will be evaluated. The examined parameters included: stability of the IOL during implantation, positioning of the IOL, rotation of the IOL, integrity of the posterior lens capsule, central visual acuity, morphology of the eye, clinical signs of inflammation, intraocular pressure, refraction.Methods: The study was carried out on 35 human eyes after using the Acri.Tec AR-1 PC/IOL after lens removal through phacoemulsification; as control, the implantation of conventional PC/IOL into the second eye of 29 patients was used. The mean follow-up was 9 + 6 months. An initial adjustment surgery of the *Acri.Tec AR-1 PC/IOL was carried out 2 weeks after implantation in 2 patients; the follow-up of these eyes was 3 and 6 months. Results: Implantation was possible without any problem. Eyes healed normally. No difference between eyes containing the *Acri.Tec AR-1 PC/IOL and eyes containing conventional PC/IOLs could be detected with respect to visual acuity, stabilization of refractive error, signs of inflammatory reaction, slitlamp microscopic aspect of the eye and intraocular pressure. As intended, initial adjustment surgery successfully changed the mydriatic refraction from +1.0 resp. +0.75 dpt to 0 resp. –0.5 dpt. 26 bilaterally pseudophakic patients including 2 patients having had adjustment surgery had more than 3 months follow-up. Mean visual acuity in the AR-1 PC/IOL group at 3 months (0.76 ±0.24) did not differ from mean visual acuity in the pseudophakic control group (0.74 ±0.23). Adjusted eyes had a visual acuity of 1.0. No adverse effects occurred. Conclusion: Initial data suggest that the *Acri.Tec AR-1 PC/IOL can be safely implanted into the capsular bag of adult human eyes and can beadjusted after implantation, thereby achieving the desired change of refraction. Further exploration of the potential usefulness of this type of reversibly adjustable PC/IOL as a tool for refractive optimization is warranted.
Retinal Arterial Macroaneurysms: Risk Factors of Poor Visual Outcome
Authors: Yang Chang-Sue , Tsai Der-Chong , Lee Fenq-Lih , Hsu Wen-Ming
Published: November 2005

Purpose: To evaluate the long-term natural course and to identify the risk factors of a poor visual outcome in patients with retinal arterial macroaneurysms (MA). Methods: In this observational case series, we retrospectively evaluated the consecutive patients with MA at our institution over a 17-year period. The visual outcomes of the different types of MA (presented as predominantly hemorrhagic or exudative) were compared. Results: A total of 31 patients with 46 confirmed MA were identified. The ocular manifestations of MA included retinal hemorrhage (96.7%), retinal exudate (61.3%), macular involvement (77.4%) and vitreous hemorrhage (12.9%). Among the 10 cases of hemorrhagic-type MA, visual acuity improved by 2 or more lines in 9 (90%) and decreased in 1 patient (10%). In the 15 cases of exudative-type MA, 4 improved (26.7%), 8 remained stationary (53.3%) and 3 had decreased visual acuity (20.0%). The average vision change in the minimum angle of resolution improved by 0.59 log units in hemorrhagic MA and decreased by 0.07 log units in exudative MA (p < 0.01). With respect to change of vision, the eyes with hemorrhagic-type MA showed greater improvement than those with the exudative type, but the final visual outcome was not different in the 2 groups. Foveal exudate was a statistically significant risk factor for final vision equal to or worse than 6/30 (odds ratio = 6.93, p < 0.05). Conclusions: Different types of MA may have different clinical presentations. In the majority of MA, there is gradual and spontaneous involution. However, poor visual outcome may occur secondary to foveal exudates and subfoveal hemorrhage.
The Role of a Second Isolated Retinal Artery in Branch Retinal Vein Obstruction
Authors: Lee Jong-Jer , Wu Pei-Chang , Chen Chih-Hsin , Chen Yung-Jen , Kuo Min-Lun , Liu Chi-Chang , Kuo Hsi-Kung
Published: November 2005

Purpose: To evaluate the prevalence of a second isolated retinal artery in eyes with and without branch retinal vein obstruction (BRVO). Methods: A retrospective study of the color photographs and fluorescein angiograms of 100 patients with unilateral BRVO (64 superotemporal and 34 inferotemporal) and a control group of 33 patients (66 eyes) with different ailments was made. The prevalence of a second isolated retinal artery, which coursed closer to the macular region, in BRVO eyes, fellow eyes and eyes of the control group was evaluated. The types and sites of arteriovenous crossings were also recorded for comparison. Results: The eyes with BRVO, which involved the superotemporal quadrant, had significantly larger numbers of arteriovenous crossings than did fellow eyes (p = 0.02) and control eyes (p = 0.001). In the superotemporal quadrant, a significantly higher percentage (35 of 66, 53%) of the control eyes had a second isolated retinal artery than did BRVO eyes (16 of 64 cases, 25%, p = 0.001). Conclusions: The second isolated retinal artery, which has not been previously mentioned in the literature, may lower the chance of arteriovenous crossings and play a protective role in BRVO.