Transcription addiction: can we garner the Yin and Yang functions of E2F1 for cancer therapy?

Classically, as a transcription factor family, the E2Fs are known to regulate the expression of various genes whose products are involved in a multitude of biological functions, many of which are deregulated in diseases including cancers. E2F is deregulated and hyperactive in most human cancers with context dependent, dichotomous and contradictory roles in almost all cancers. Cancer cells have an insatiable demand for transcription to ensure that gene products are available to sustain various biological processes that support their rapid growth and survival. In this context, cutting-off hyperactivity of transcription factors that support transcription dependence could be a valuable therapeutic strategy. However, one of the greatest challenges of targeting a transcription factor is the global effects on non-cancerous cells given that they control cellular functions in general. Recently, there is growing realization regarding the possibility to target the oncogenic activation of transcription factors to modulate transcription addiction without affecting the normal activity required for cell functions. In this review, we used E2F1 as a prototype transcription factor to address transcription factor activity in cancer cell functions. We focused on melanoma considering that E2F1 executes critical functions in response to UV, an etiological factor of cutaneous melanoma and lies immediately downstream of the CDKN2A/pRb axis, which is frequently deregulated in melanoma. Further, activation of E2F1 in melanomas can also occur independent of loss of CDKN2A. Given its activated status and the ability to transcriptionally control a plethora of genes involved in regulating melanoma development and progression, we review the current literature on its differential role in controlling signaling pathways involved in melanoma as well as therapeutic resistance, and discuss the practical value of weaning melanoma cells from E2F1-mediated transcription dependence for melanoma management.

First Report of Fusarium acuminatum on Pigeonpea in India

Pigeonpea (Cajanus cajan (L.) Millsp.) is the most important protein rich grain legume crop being cultivated worldwide. During surveys (2010 through 2012) conducted in major pigeonpea growing states in southern and central India (Andhra Pradesh, Karnataka, and Maharashtra), rapid mortality of pigeonpea plants was observed. This occurred in all of the surveyed areas with disease incidence of 20 to 60% irrespective of cultivar and crop growth stage. Symptoms included chlorosis, drooping and rolling of the leaves followed by rapid mortality of whole plant. Pinkish growth on infected stems and branches was observed and the inner layer of the infected stem had brown discoloration. Xylem vessels of the infected plants were healthy and did not show any blackening. Isolations from infected stem tissues consistently yielded cultures of Fusarium sp. on potato dextrose agar (PDA) medium. Monoconidial isolation from three separate isolates was used to establish pure cultures. The morphological characters of the fungus were consistent with descriptions in Fusarium keys (1) for Fusarium acuminatum (Ellis & Everhart). The mean colony growth was 86 mm after 7 days, with white aerial mycelium developing brownish pigmentation in the center on PDA. The dorsal side of the colony had rose to burgundy pigmentation. Macroconidia were broadly falcate with 3 to 5 septa, and were 3 to 8 × 39 to 64 μm. Microconidia were absent and chlamydospores formed in chains of 20 to 50 μm. Koch's postulates were established on seedlings of pigeonpea (cv. ICP 7119) using root dip inoculation of 10-day-old seedlings. The roots were immersed in a conidial suspension (6 × 10⁶ conidia/ml) for 2 to 3 min; the control plants' roots were immersed in sterilized distilled water in a beaker. Inoculated seedlings were transplanted into pre-irrigated pots (12 cm) containing sterilized vertisol and sand (3:1). Five seedlings were used for each of three replications. Inoculated plants were kept in the greenhouse at 28 ± 2°C and irrigated with sterilized water. Inoculated plants developed symptoms identical to those observed in the field and disease incidence reached 100% within 96 h after inoculation. The experiment was conducted twice with two independent sets of plants. No symptoms were observed in water-inoculated control plants. The rDNA internal transcribed spacer (ITS sequence) was amplified with ITS1 and ITS4 primers (4). The amplicons of both forward and reverse (438 bp) were sequenced and submitted to GenBank (Accession No. JX177431). A BLASTn search revealed 100% sequence similarity to the nucleotide sequence of F. acuminatum (Ellis & Everhart) (GenBank Accession No. HQ443205). To our knowledge, this is the first report with confirmed molecular identification of F. acuminatum on pigeonpea. Occurrence of F. acuminatum on various plant species have been reported by Summerell et al. (3). Presence of F. acuminatum from soils of pigeonpea fields have been reported; however, no information on location, symptoms, plant mortality, and identification of pathogen has been provided (2). References: (1) J. F. Leslie and B. A. Summerell. Pages 122-123 in: The Fusarium Laboratory Manual. Blackwell Publishing Professional, Hoboken, NJ, 2006. (2) A. P. Singh and S. N. Bhargava. Phytopathol. Z. 100:300, 1981. (3) B. A. Summerell et al. Fungal Diversity 46:1, 2011. (4) T. J. White et al. Pages 315-322 in: PCR protocols: Guide to Methods and Applications, San Diego, Academic Press, 1990.

Study of CC chemokine receptor 5 in renal allograft rejection

Allospecific recruitment of T cells is primary to the pathogenesis of renal transplant rejection. Chemokines and their receptors inducing a Th1 cytokine response play a central role in this recruitment. Renal allograft biopsies of 28 patients with acute cellular rejection and 10 protocol biopsies (controls) were examined in accordance with Banff grading 2007 schema. Immunohistochemistry for CD3 and CC chemokine receptor 5 (CCR5) in sequential sections was performed and quantitatively assessed in the glomeruli, tubules, and interstitium. Histopathologic and clinical correlations were carried out. CD3- and CCR5-positive cells were observed in significantly higher numbers in rejection cases than in controls (P = 0.010). A larger proportion of CCR5-positive cells were noted in the foci of tubulitis compared to the interstitial infiltrates and glomeruli in all cases, and it correlated with the grade of cellular rejection (P = 0.010). A greater number of CCR5-positive cells were seen in early rejection (<6 months posttransplant) compared to late rejection. No clinical correlation with serum creatinine levels was found. CCR5-positive cells represent the alloaggressive subset of T cells in ACR, and their numbers correlate with rejection severity. CCR5 may be used as a marker of early acute rejection and may be an important target for future antirejection therapies.

Solvent Effects upon the Electronic Absorption and Fluorescence Spectra of Pteridines and Riboflavin and Their Ground and First Excited Singlet State Dipole Moments

The electronic absorption. fluorescence excitation, and fluorescence emission spectra of a series of pteridines (lumazine, xanthopterin, isoxanthopterin, biopterin) and riboflavin (vitamin B2) were measured at room temperature (298 K) in a number of solvents covering a wide range of polarities (dioxane, ethyl ether, chloroform, ethyl acetate, 1-butanol. 2-propanol, ethanol, methanol, dimethylformamide, acetonitrile, and dimethyl sulfoxide). The effects of the solvent upon the spectral properties are discussed. Experimental groundstate dipole moments were measured for selected compounds and were used in combination with the spectral data to evaluate their first excited singlet-state dipole moments by means of the solvatochromic shift method (Bakhshiev's and Kawski-Chamma-Viallet's equations based on the variation of the Stokes shift with the solvent dielectric constant-refractive index term). The theoretical ground and excited singlet-state dipole moments for all pteridines and riboflavin were calculated as a vector sum of the π-component (obtained by the PPP method) and the a-component (obtained from a-bond moments). A second set of theoretical values was obtained by using the CNDO/2method. A good agreement was observed between the experimental and the theoretical values. Excited singlet-state dipole moments are higher than the ground state values by 1 to 6 Debye units for all the pteridines under study with the exception of xanthopterin.

Intensity noise correlations in a two-frequency VECSEL

We present an experimental and theoretical study of the intensity noise correlation between the two orthogonally polarized modes in a dual frequency Vertical External Cavity Surface Emitting Laser (VECSEL). The dependence of the noise correlation spectra on the non-linear coupling between the two orthogonally polarized modes is put into evidence. Our results show that for small coupling the noise correlation amplitude and phase spectra remain nearly flat (around -6 dB and 0° respectively) within the frequency range of our interest (from 100 kHz to 100 MHz). But for higher values of the coupling constant the low frequency behaviors (below 1-2 MHz) of the correlation amplitude and phase spectra are drastically changed, whereas above this cut-off frequency (1-2 MHz) the correlation spectra are almost independent of coupling strength. The theoretical model is based on the assumptions that the only source of noise in the frequency range of our interest for the two modes are pump noises, which are white noises of equal amplitude but partially correlated.

Alternaria tenuissima Causing Alternaria Blight on Pigeonpea in India

Pigeonpea (Cajanus cajan (L.) Millsp.) is a major grain legume of the tropics and subtropics worldwide. In India, pigeonpea is the third most important food legume after chickpea and field pea. Blight symptoms on pigeonpea were observed in alarming proportion during the 2009 through 2011 crop seasons in Andhra Pradesh state in India. Disease incidence ranged from 20 to 80% irrespective of cultivars sown. Infected plants in the field showed symptoms on all aerial parts of the plant (leaves, stems, buds, and pods) irrespective of age of the plant and leaves. Symptoms on leaves were small, circular, necrotic spots that developed quickly forming typical concentric rings (1). Later, these spots coalesced and caused blighting of leaves. Spots were initially light brown and later turned dark brown. On stems, spots were sunken with concentric rings. In severe infection, defoliation and drying of infected leaves, branches, and flower buds was observed. The fungus was successfully isolated from all the infected plant parts (leaves, stem, buds, and pods) on potato dextrose agar (PDA) medium. After 4 to 5 days of incubation at 28 ± 1°C with a 12-h photoperiod, the fungus produced colonies that were regular and flat. The periphery of the colony was olive green with a black center. Monoconidial isolations were used to establish a pure culture of the fungus. Conidiophores were short, arising singly, and were 8.86 mm long and 2.97 mm thick. Conidia varied from 15.78 to 28.70 mm long and 8.03 to 13.47 mm wide. Very small beak (1.6 to 3.2 mm) or no beak was observed. Horizontal and vertical septations of conidia varied from four to six and two to four, respectively. The pathogenicity test was conducted on 8- to 10-day-old pigeonpea plants of cultivar ICPL 87119 by spraying with a conidial suspension (5 × 10⁵ conidia/ml). Inoculated plants were covered with polythene bags and kept in a greenhouse at 28 ± 1°C with a 12-h photoperiod. After 48 h, the polythene bags were removed. Ten days after inoculation, symptoms were similar to those observed in fields. This experiment was conducted twice with two independent sets of plants. No symptoms were observed in water-inoculated control plants. The fungus was reisolated from the inoculated plants. On the basis of the morphological characteristics, the pathogen was tentatively identified as Alternaria tenuissima. The identification was further confirmed by the rDNA and internal transcribed spacer (ITS) primer. The ITS region of rDNA was amplified with ITS 1 and ITS 4 primers. Both orientation sequenced amplicons (481 bp) were submitted to GenBank (Accession No. JQ074094). A BLASTn search revealed 99% similarity to A. tenuissima (Accession No. HQ343444). To our knowledge, this is the first report of molecular identification of A. tenuissima causing Alternaria blight in pigeonpea in India. Reference: (1) Kannaiyan, J. and Nene, Y. L. 1977. Trop. Grain Legume Bull. 9:34.

The control of hyperglycemia in alloxan treated diabetic mice through the stimulation of hepatic insulin synthesis due to the production of nitric oxide

OBJECTIVE

The hepatocytes from the adult mice when stimulated by glucose had been reported to synthesize and secrete insulin. The feasibility of controlling hyperglycemia in alloxan induced diabetic mice through hepatic synthesis of insulin was studied.

MATERIALS AND METHODS

Insulin synthesis was determined by in vitro translation of mRNA and by immunohistochemistry of the hepatocytes and assayed by enzyme linked immunosorbent assay (ELISA). Dermcidin isoform 2 (dermcidin) was measured by ELISA. Nitric oxide was measured by methemoglobin method. Insulin synthesis was quantitated by immunoblot technique and the expression of proinsulin genes I and II in the hepatocytes was quantitated by cDNA synthesis.

RESULTS

It was found that in contrast to normal hepatocytes, the hepatocytes from the diabetic mice showed impaired insulin synthesis in the presence of glucose that was related to the inhibition of nitric oxide synthesis through the synthesis of dermcidin, a potent competitive inhibitor of nitric oxide synthase. The increase of systemic NO synthesis either by oral use of 0.7 mM acetyl salicylic acid (aspirin) or by dermal application of 0.28 mmol sodium nitroprusside in saline soaked in cotton pad was found to decrease blood glucose level from 600 mg/dL to 120 mg/dL with concomitant increase of plasma insulin level from 5 µunits/dL to 38 µunits/dL. And subsequently normalized dermcidin level from 80 nM to 4.5 nM within 24 h (p<0.001; n=10).

CONCLUSION

Our studies suggested the possibility of controlling hyperglycemia in alloxan induced diabetic mice by the stimulation of the hepatic insulin synthesis through the systemic stimulation of NO production in the hepatocytes.

Observation of noise phase locking in a single-frequency VECSEL

We present an experimental observation of phase locking effects in the intensity noise spectrum of a semiconductor laser. These noise correlations are created in the medium by coherent carrier-population oscillations induced by the beatnote between the lasing and non-lasing modes of the laser. This phase locking leads to a modification of the intensity noise profile at around the cavity free-spectral-range value. The noise correlations are evidenced by varying the relative phase shift between the laser mode and the non-lasing adjacent side modes.

Photon lifetime in a cavity containing a slow-light medium

We investigate experimentally the lifetime of the photons in a cavity containing a medium exhibiting strong positive dispersion. This intracavity positive dispersion is provided by a metastable helium gas at room temperature in the electromagnetically induced transparency regime, in which light propagates at a group velocity of the order of 10⁴ m·s⁻¹. The results definitely prove that the lifetime of the cavity photons is governed by the group velocity of light in the cavity and not its phase velocity.

Emergency presentations of Parkinson's disease: early recognition and treatment are crucial for optimum outcome

Parkinson's disease (PD) is a debilitating condition associated with significant morbidity and mortality. Pathophysiologically the illness is due to a disruption of dopamine production in the basal ganglia and leads to a wide array of symptoms. These symptoms are not restricted to the nervous system; thus, the illness often presents acutely to a wide range of specialties, many of which may have limited experience in the condition. Patients often become unwell with illnesses unrelated to their PD. However, these conditions frequently lead to a deterioration in PD control. In addition, there exist certain acute complications of PD which are often difficult to recognise and carry significant mortality. Discussing the acute presentations of the illness under the umbrella of PD is important as it enables clinicians to focus upon the specific concerns involved in managing patients with the illness. A number of conditions are extremely common in PD and include falls, orthostatic hypotension, swallowing difficulties, psychosis, and hyperkinetic movement disorders. Optimal treatment of these conditions requires the consideration of issues specific to PD. Lesser recognised acute presentations of PD include the serotonin syndrome and neuroleptic malignant-like syndrome. While encountered less commonly, these conditions have been well described in the literature and untreated may prove fatal. They require urgent management, with their importance being further highlighted by the fact they may often mimic other illnesses, making diagnosis difficult. Therapeutic interventions aimed at treating PD and preventing its complications are evolving rapidly.

Optimization of the Sistrom Culture Medium for Large-Scale Batch Cultivation of Rhodospirillum rubrum under Semiaerobic Conditions with Maximal Yield of Photosynthetic Membranes

The defined medium A of W. R. Sistrom (W. R. Sistrom, J. Gen. Microbiol. 22:77-85, 1960) has been modified to allow the growth of Rhodospirillum rubrum in large-scale batch cultures under dark, semiaerobic conditions. The simultaneous use of two substrates, NH(4)-succinate (46 mM) and fructose (0.3%), which are utilized in aerobic and fermentative metabolism, respectively, leads to very high cell densities with a maximal yield of photosynthetic membranes.

Measurement of the coupling constant in a two-frequency VECSEL

We measure the coupling constant between the two perpendicularly polarized eigenstates of a two-frequency Vertical External Cavity Surface Emitting Laser (VECSEL). This measurement is performed for different values of the transverse spatial separation between the two perpendicularly polarized modes. The consequences of these measurements on the two-frequency operation of such class-A semiconductor lasers are discussed.

Differential Signaling by ErbB Receptor (HER) Dimers: Implications for Response to Anti-HER2 Therapies in Breast Cancer

The ErbB family of receptor tyrosine kinases comprises of EGFR, HER2, HER3 and HER4. Ligand binding induces receptor homo- and heterodimerization and activation of downstream signaling. No ligand(s) have been identified for HER2. Recruitment of HER2 to ligand-activated co-receptors potentiates signaling by HER2-containing heterodimers. To identify differential signaling induced by HER2/HER3 and HER2/EGFR heterodimers and HER2 homodimers, we developed a cell system where HER2 dimerization can be conditionally regulated. A retroviral vector encoding HA-tagged full-length human HER2 fused to ligand-binding domain of FK506 binding protein (FKBP) in the C-terminus was stably transduced into MCF10A mammary epithelial cells. Treatment of MCF10A-HER2-FKBP-HA cells with the intracellular dimerizer AP1510 resulted in homodimerization and tyrosine phosphorylation of the HER2 chimera. The EGFR ligands EGF and TGFα and the HER3 ligand heregulin induced HER2/EGFR and HER2/HER3 heterodimers. Microarray analysis with RNA isolated from vehicle, AP1510, TGFα and heregulin treated cells identified unique transcriptional activities associated with HER2/HER2, HER2/HER3 and HER2/EGFR induced signaling. Ingenuity Pathway analysis of the microarray data showed that HER2 homodimers had the most significant effect on the “G2/M DNA damage checkpoint regulation pathway” whereas HER2/EGFR dimers had the most pronounced effect on the “pyrimidine metabolism pathway”. Active HER2/HER3 dimers affected the NF-κB signaling pathway the most.To determine if differential signaling by ErbB dimers have any implications for the response to anti-HER2 therapies, we treated MCF10A-HER2-FKBP-HA cells with AP1510, TGFα or heregulin in the presence or absence of trastuzumab, pertuzumab or lapatinib. In 3D Matrigel, AP1510-treated cells formed invasive acini while untreated cells failed to grow. EGF and TGFα and heregulin also stimulated acini growth in 3D. The anti-HER2 antibody trastuzumab completely inhibited AP1510-stimulated but not EGF, TGFα, or heregulin-stimulated growth. Lapatinib, a dual inhibitor of the HER2 and EGFR tyrosine kinases, blocked EGF, heregulin, and AP1510-induced growth. Pertuzumab, an antibody that blocks ligand-induced HER2 heterodimerization, inhibited heregulin-induced but not AP1510-induced growth. Reverse Phase Protein Array performed with lysates from cells treated with AP1510, TGFα or heregulin indicated that AP1510 failed to activate S473 p-AKT. This is a key enzyme in the PI3K pathway, which has been associated with resistance to HER2 inhbitors. Western blot analyses showed that AP1510 induced p-ERK whereas TGFα and Heregulin activated p-AKT. Binding assays with 125I-labeled trastuzumab indicated that treatment with AP1510 enhanced binding of trastuzumab compared to untreated cells. This result suggests that HER2 homodimers present a conformation to which trastuzumab binds better. Taken together, these data suggest that 1) because of their inability to activate Akt, cells dependent on HER2-containing homodimers are less able to bypass trastuzumab action; and 2) high levels of HER2 homodimers in breast cancers with HER2 gene amplification may represent a biomarker predictive of response to trastuzumab.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 705.

Observation of electromagnetically induced transparency and slow light in the dark state--bright state basis

The quantum coherence phenomenon of electromagnetically induced transparency (EIT) is observed in a three-level system composed of an excited state and two coherent superpositions of the two ground-state levels. This peculiar ground state basis is composed of the so-called bright and dark states of the same atomic system in a standard coherent population trapping configuration. The characteristics of EIT, namely, width of the transmission window and reduced group velocity of light, in this unusual basis, are theoretically and experimentally investigated and are shown to be essentially identical to those of standard EIT in the same system.