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PDF file - 25K, MIG6 mediates the effects of miR-148a on cell proliferation.

PDF file - 72K

PDF file - 247K, Transfection efficiency of U87 cells infected with lentiviruses encoding anti-miR-148, mCherry, and hygromycin resistance gene.

PDF file - 17K, BIM mediates the effects of miR-148a on aopotosis.

PDF file - 23K, miR-148a inhibits MIG6 and BIM mRNA expression.

PDF file - 30K, miR-148a levels after transfection with pre-miR-148a.

PDF file - 636KB, Supplemental Table S1: information of the GBM lines used in this paper. Supplemental Table S2: information of the patient clinical data for Figure 1. Supplemental Table S3: Percentage of cells positive for staining with PRMT5 in spontaneous high grade astrocytoma from Mut3 strain (GFAP-cre; cisNf1-/+; P53-/-) and normal brain tissue from wild-type control mouse stained by PRMT5 and ki-67 antibody. Supplemental table S4. GBM cell line (U251) was transfected by scramble control or si-PRMT5. Affymetrix microarray genechip was performed in three independent experiments to evaluate genes up-regulated with PRMT5 silencing.

PDF file - 1690KB, Supplemental Figure S1. PRMT5 is over-expressed in human GBM cell lines. Supplemental Figure S2: High grade astrocytomas Supplemental Figure S3: efficacy and specificity of PRMT5 knock-down by lead siRNA. Supplemental Figure S4: PRMT5 Knockdown promotes cell death of human GBM cells Supplemental Figure S5: si-PRMT5 induced cell death is P53-independent Supplemental Figure S6: Decreased ST7 expression correlates with worse survival in all glioma patients (grade I-IV). Supplemental Figure S7: Over-expression of ST7 in three GBM cell lines was confirmed by real-time PCR and western blot (top panels).

Glioblastoma is the most common and aggressive histologic subtype of brain cancer with poor outcomes and limited treatment options. Here, we report the selective overexpression of the protein arginine methyltransferase PRMT5 as a novel candidate theranostic target in this disease. PRMT5 silences the transcription of regulatory genes by catalyzing symmetric dimethylation of arginine residues on histone tails. PRMT5 overexpression in patient-derived primary tumors and cell lines correlated with cell line growth rate and inversely with overall patient survival. Genetic attenuation of PRMT5 led to cell-cycle arrest, apoptosis, and loss of cell migratory activity. Cell death was p53-independent but caspase-dependent and enhanced with temozolomide, a chemotherapeutic agent used as a present standard of care. Global gene profiling and chromatin immunoprecipitation identified the tumor suppressor ST7 as a key gene silenced by PRMT5. Diminished ST7 expression was associated with reduced patient survival. PRMT5 attenuation limited PRMT5 recruitment to the ST7 promoter, led to restored expression of ST7 and cell growth inhibition. Finally, PRMT5 attenuation enhanced glioblastoma cell survival in a mouse xenograft model of aggressive glioblastoma. Together, our findings defined PRMT5 as a candidate prognostic factor and therapeutic target in glioblastoma, offering a preclinical justification for targeting PRMT5-driven oncogenic pathways in this deadly disease. Cancer Res; 74(6); 1752–65. ©2014 AACR.

PDF file - 20K, Transfection efficiency of U87 cells infected with lentiviruses encoding anti-miR-148, mCherry, and hygromycin resistance gene.

Cellular senescence can induce dual effects (promotion or inhibition) on cancer progression. While immune cells naturally respond and migrate toward various chemotactic sources from the tumor mass, various factors including senescent tumor cells (STCs) in the tumor microenvironment may affect this chemotactic movement. In this work, we investigate the mutual interactions between the tumor cells and the immune cells that either inhibit or facilitate tumor growth by developing a mathematical model that consists of taxis-reaction-diffusion equations and receptor kinetics for the key players in the interaction network. We apply a mathematical model to a transwell Boyden chamber invasion assay used in the experiments to illustrate that STCs can play a pivotal role in negating immune attack through tight regulation of intra- and extra-cellular signaling molecules. In particular, we show that senescent tumor cells in cell cycle arrest can block intratumoral infiltration of CD8+ T cells by secreting a high level of CXCL12, which leads to significant reduction its receptors, CXCR4, on T cells, and thus impaired chemotaxis. The predictions of nonlinear responses to CXCL12 were in good agreement with experimental data. We tested several hypotheses on immune-tumor interactions under various biochemical conditions in the tumor microenvironment and developed new concepts for anti-tumor strategies targeting senescence induced immune impairment.

Glioblastoma (GBM) is the most common form of primary malignant brain tumor. Current treatment consists of tumor resection followed by chemoradiotherapy which yields a 5-year survival rate of only 6.8%. The average survival for newly diagnosed patients is only 14-15 months, highlighting the need for improved therapies. The tumor microenvironment (TME) of GBM is highly immunosuppressive, preventing successful treatment by immunotherapies like immune checkpoint blockade. Our lab is interested in identifying potential targets in GBM that would allow for increased immune infiltration in the tumor microenvironment, thus enhancing the efficacy of immunotherapies. Stimulator of interferon genes (STING) plays a central role in innate pathogen sensing and has been implicated in cancer as a potential immunostimulatory therapeutic target. Our previous work demonstrated the functionality of the STING pathway in GBM mouse models and patient samples. We have also shown increased infiltration of innate immune cells in the TME and significant survival benefits after treatment with the STING agonist ADU-S-100 in GL261 and CT-2A mouse models. In vitro studies in cultured GBM cell lines and normal cells found in the GBM TME such as human cerebral microvascular endothelial cells (HCMECs) in the presence of ADU-S100 showed a robust type I IFN response in endothelial cells but not in tumor cells. Western blotting showed the presence of all the major STING signaling pathway components in GBM cells, raising the question of how the STING pathway is regulated in tumor cells. To investigate this further we have performed cytokine profiling of GBM cells and HCMECs upon treatment with ADU-S100. This confirmed a strong Type I interferon response in HCMECs, and a distinct response in GBM cells, showing that tumor cells respond to STING activity via alterations in cytokine secretion, but in a different way from TME cells. Finally, manganese has been highlighted as a possible potentiator of STING agonist activity in other cancer types. Combination of manganese with ADU-S100 showed enhanced protein expression of downstream STING pathway components in HCMECs as well as in GBM cells through Western blot. Furthermore, manganese alters the cytokine profile in combination with ADU-S100 relative to untreated or ADU-S100 alone suggesting enhancement of immune signaling. Taken together, these results suggest potentiation of ADU-S100 by manganese in GBM. In conclusion, STING agonists are promising agents for local immunostimulation in GBM, and their activity may be enhanced by combination with manganese. Ongoing experiments are aimed at elucidating mechanistic insights into these concepts. Citation Format: Andrea Schmidt, Caroline Sweeney, William M. Hawkins, Jorge L. Jimenez-Macias, Sean Lawler. Assessment of the response to STING agonist treatment and potentiation by manganese in glioblastoma cells and the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2277.

Immune surveillance of the brain is regulated by resident non-neuronal cells and the blood-brain barrier.1 Dys-regulation of immunosurveillance is a hallmark feature of several diseases2–5 including brain tumors6 that interact with and rely heavily on immune cells,7 suggesting that disrupting the neuroimmunology of tumors could slow their progression. Yet few tools are available to control brain immunology in vivo with local precision, and fewer yet are used for therapeutic intervention. 2 Here, we propose engineered cytokines as a neuroimmune-modulation platform. We demonstrate that the residence time of cytokines in the brain can be tuned by binding them to the extracellular matrix or synthetic scaffolds. We then show that the aluminum hydroxide adjuvant (alum) is retained in the brain >2 weeks. Tethering of inflammatory cytokines such as interleukins (IL) 2 and 12 to alum yields extended neuroinflammation and brain immunosurveillance after intracranial administration, while avoiding systemic toxicity. In mouse models of both immunologically hot and cold brain tumors, the intracranial deposition of alum-tethered cytokines causes significant delay in tumor progression. RNA profiling reveals that engineered cytokines engage both innate and adaptive immunity in the brain. These findings suggest that engineered cytokines can reprogram brain immunosurveillance, informing the development of future therapies for neuroimmune diseases.

Oncolytic viruses (OVs) are emerging cancer immunotherapy. Despite notable successes in the treatment of some tumors, OV therapy for central nervous system cancers has failed to show efficacy. We used an

BackgroundIntratumoral viral oncolytic immunotherapy is a promising new approach for the treatment of a variety of solid cancers. CAN-2409 is a replication-deficient adenovirus that delivers herpes simplex virus thymidine kinase to cancer cells, resulting in local conversion of ganciclovir or valacyclovir into a toxic metabolite. This leads to highly immunogenic cell death, followed by a local immune response against a variety of cancer neoantigens and, next, a systemic immune response against the injected tumor and uninjected distant metastases. CAN-2409 treatment has shown promising results in clinical studies in glioblastoma (GBM). Patients with GBM are usually given the corticosteroid dexamethasone to manage edema. Previous work has suggested that concurrent dexamethasone therapy may have a negative effect in patients treated with immune checkpoint inhibitors in patients with GBM. However, the effects of dexamethasone on the efficacy of CAN-2409 treatment have not been explored.MethodsIn vitro experiments included cell viability and neurosphere T-cell killing assays. Effects of dexamethasone on CAN-2409 in vivo were examined using a syngeneic murine GBM model; survival was assessed according to Kaplan-Meier; analyses of tumor-infiltrating lymphocytes were performed with mass cytometry (CyTOF - cytometry by time-of-flight). Data were analyzed using a general linear model, with one-way analysis of variance followed by Dunnett’s multiple comparison test, Kruskal-Wallis test, Dunn’s multiple comparison test or statistical significance analysis of microarrays.ResultsIn a mouse model of GBM, we found that high doses of dexamethasone combined with CAN-2409 led to significantly reduced median survival (29.0 days) compared with CAN-2409 treatment alone (39.5 days). CyTOF analyses of tumor-infiltrating immune cells demonstrated potent immune stimulation induced by CAN-2409 treatment. These effects were diminished when high-dose dexamethasone was used. Functional immune cell characterization suggested increased immune cell exhaustion and tumor promoting profiles after dexamethasone treatment.ConclusionOur data suggest that concurrent high-dose dexamethasone treatment may impair the efficacy of oncolytic viral immunotherapy of GBM, supporting the notion that dexamethasone use should be balanced between symptom control and impact on the therapeutic outcome.

A status-quo in targeted cancer therapy is that out of the thousands of somatic alterations found in a cancer cell, alterations only in driver genes determine therapeutic strategy. Despite unimpressive results of some driver-targeted therapies, and given that the majority of genomic alterations in cancer are not ‘drivers’, but ‘passengers’ / bystander alterations, it remains underappreciated whether targeting built-in vulnerabilities imposed by passenger gene alterations may provide therapeutic value. The tumor suppressor PTEN undergoes widespread functional inactivation including deletion in human cancer. PTEN deletion occurs frequently in GBM, sometimes as part of the 10q loss or chromosome 10 monosomy. We discovered that several genes including Stearoyl Co-A Desaturase, SCD (10q24.31), located 12 MB telomeric to PTEN is frequently co-deleted hemizygously and unintentionally in PTEN-deleted cancers. Strikingly, in a subset of GBM, SCD was also epigenetically silenced. A combination of SCD deletion and methylation resulted in two molecular subgroups – one that expressed SCD, and another that showed little or no detectable SCD. SCD, is an integral membrane protein of the endoplasmic reticulum and converts saturated fatty acids to monounsaturated fatty acids (Oleic and palmitoleic acids) that are critical for membrane fluidity and function, and thus SCD is generally overexpressed in most cancers. We show that SCD expressing lines are highly sensitive to multiple SCD inhibitors, while non-expressors are resistant. Despite modest BBB penetration, one SCD inhibitor was remarkably efficient in blocking intracranial tumor growth. SCD is an oxygen-dependent enzyme. We show that SCD retains significant enzymatic activity even in highly hypoxic conditions. Finally, through RNAseq, functional proteomics and ATACseq, we demonstrate an evolutionarily conserved mechanism of acquired resistance to SCD inhibitor through drug-induced acute phase signaling response in multiple SCD expressing cancers.

Simple Summary High-grade gliomas remain difficult-to-treat cancers. Novel treatment options include targeting glycogen synthase kinase 3 (GSK-3) to induce cell death but the mode of drug activity remains unknown and combination with conventional treatment including radiotherapy has not been explored. Here, we describe the effect of targeting GSK-3 with the inhibitor AZD2858 in in vitro and in vivo models of glioma. We established that AZD2858 exposure induces mitotic defects leading to cell death in patient-derived glioma cell lines and tumor growth delay in glioma xenografts. Co-administration also enhanced the effect of radiotherapy. We therefore propose AZD2858 as an adjuvant to radiotherapy in high-grade glioma. Abstract Background: Previous data on glycogen synthase kinase 3 (GSK-3) inhibition in cancer models support a cytotoxic effect with selectivity for tumor cells compared to normal tissue but the effect of these inhibitors in glioma has not been widely studied. Here, we investigate their potential as cytotoxics in glioma. Methods: We assessed the effect of pharmacologic GSK-3 inhibition on established (U87, U251) and patient-derived (GBM1, GBM4) glioblastoma (GBM) cell lines using cytotoxicity assays as well as undertaking a detailed investigation of the effect on cell cycle, mitosis, and centrosome biology. We also assessed drug uptake and efficacy of GSK-3 inhibition alone and in combination with radiation in xenograft models. Results: Using the selective GSK-3 inhibitor AZD2858, we demonstrated single agent cytotoxicity in two patient-derived glioma cell lines (GBM1, GBM4) and two established cell lines (U251 and U87) with IC50 in the low micromolar range promoting centrosome disruption, failed mitosis, and S-phase arrest. Glioma xenografts exposed to AZD2858 also showed growth delay compared to untreated controls. Combined treatment with radiation increased the cytotoxic effect of clinical radiation doses in vitro and in orthotopic glioma xenografts. Conclusions: These data suggest that GSK-3 inhibition promotes cell death in glioma through disrupting centrosome function and promoting mitotic failure and that AZD2858 is an effective adjuvant to radiation at clinical doses.

Glioblastoma, the most common and aggressive primary brain tumor, is rapidly growing and highly infiltrative. Incomplete knowledge of the molecular biology, genetics, causes and cellular origin of these tumors may limit the development of improved therapeutics. A major and fundamental advance in recent years has been the identification of microRNAs as highly conserved regulators of gene expression. Here we will discuss further our recently published data on the role of miR-451 in the biology of glioblastoma. We initially identified miR-451 due to its downregulation in a glioma cell migration assay. We then found that by targeting the LKB1 kinase complex miR-451 suppresses the activity of downstream protein kinases including the major energy biosensor AMPK. MiR-451 levels are regulated by glucose; under conditions of abundant energy miR-451 expression is high, and the suppression of AMPK signaling allows cells to maintain elevated proliferation rates via unrestrained mTOR activation. Under conditions of glucose withdrawal, miR-451 downregulation is necessary for AMPK pathway activation, leading to suppressed proliferation rates, increased cell survival and migration. We also identified a potential feedback loop between LKB1 and miR-451, which allows a sustained and robust response to glucose deprivation. This data will be discussed in the context of potential biological significance and therapeutic implications.

In this study, we uncovered microRNA-148a (miR-148a) as a novel prognostic and oncogenic microRNA in glioblastoma (GBM). MiR-148a expression was significantly higher in human GBM tissues, cell lines and stem cells (GSCs) as compared to normal human brain and astrocytes. High miR-148a levels were a risk indicator for GBM patient survival. MiR-148a increased GBM cell and GSC growth, survival, migration, and invasion as well as GSC neurosphere formation. We identified the EGFR regulator, MIG6, and the apoptosis regulator, BIM as two direct targets of miR-148a and showed with rescue experiments that they mediate the oncogenic effects of miR-148a. Importantly, by inhibiting MIG6 expression, miR-148a reduced EGFR trafficking to the Rab7-expressing late endosome/lysosomal compartments. This coincided with a reduction of EGFR degradation and induction of EGFR expression and activation. Lastly, inhibition of miR-148a expression led to a strong inhibition of GSC and GBM xenograft growth in vivo. These findings represent the first comprehensive analysis of the role of miR-148a in GBM. They show that miR-148a expression levels are predictive of patient survival and that this microRNA enhances malignancy by inhibiting apoptosis and indirectly activating EGFR. These results also suggest that miR-148a is a potential target for GBM therapy. Citation Format: Jungeun Kim, Ying Zhang, Michael Skalski, Josie Hayes, Benjamin Kefas, David Schiff, Benjamin Purow, Sarah Parsons, Sean Lawler, Roger Abounader. microRNA-148a is a prognostic oncomiR that targets MIG6 and BIM to regulate EGFR and apoptosis in glioblastoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5222. doi:10.1158/1538-7445.AM2014-5222

Brain metastases remain a serious obstacle that negatively impacts cancer patient survival. Nearly 180,000 patients in the U.S. are diagnosed annually with metastatic brain lesions, more than ten times the incidence of primary brain tumors such as glioblastoma. Brain metastases remain a challenging complication despite advances in surgical, chemo-radiation and targeted therapies. Most deaths due to cancer result from the progressive growth of metastatic, drug-resistant lesions. Moreover, the incidence of brain metastases is rising as a result of superior imaging modalities, earlier cancer detection and more effective treatment of systemic disease. To investigate the role of the brain microenvironment in metastasis, lung and breast tumor cells were co-cultured with astrocytes, the most abundant normal cell type in the metastatic brain tumor niche. Astrocyte co-culture led to increased tumor cell viability, proliferation and chemoresistance. After co-culture with astreocytes, tumor cells were then removed and total RNA was isolated. A panel of individual microRNAs (miRNAs) were identified that were reduced in tumor cells after co-culture. The rationale for developing miRNA therapeutic replacements is based upon the premise that aberrantly expressed miRNAs play a key role in controlling tumorigenesis, drug resistance and metastasis. Correcting these miRNA deficiencies through antagonisitc or replacement of miRNA function may provide a therapeutic benefit. Microarray-based profiling revealed that astrocyte co-culture reduced miRNAs-768-3p, 886-5p and 200c in the lung tumor cells. Vector-based forced expression of sequence complementary to miRNA768-3p or transfection of inhibitory miRNA-768-3p oligonucleotide inhibitors into tumor cells led to increased cell growth. Also, inhibition of miRNA-768-3p increased KRas expression, and a specific binding site was identified in the KRas 3′UTR was validated using a luciferase construct. Moreover, shRNA-mediated KRas knockdown reduced growth-promotion by the miRNA-768-3p inhibitor. MiRNA-768-3p levels were lower in tissue samples obtained from patients diagnosed with brain metastases relative to normal human adult brain tissue. In addition, the level of miRNA-768-3p was lower in tissue from patients diagnosed with brain metastases compared to the primary tumors in matched paired samples obtained from the same patient. The results demonstrate that the brain microenvironment modulates numerous miRNA, sush as miRNA-768-3p, in metastatic lesions to enhance KRas-mediated tumor growth and drug resistance and ultimately to promote brain metastasis. The therapeutic application of miRNA may allow for the rapid and coordinated manipulation of proteins that regualte multiple key intracellular pathways that promote tumorigenesis and metastasis. Citation Format: James J. Driscoll, Arasakumar Subramani, Samer Alsidawi, Sajjeev Jagannathan, Kazutaka Sumita, Atsuo Sasaki, Ronald E. Warnick, Sean Lawler. Microenvironment-induced changes in miRNA levels promote brain metastasis, drug resistance and KRA expression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-277. doi:10.1158/1538-7445.AM2013-LB-277

Pro-inflammatory T cells mediate autoimmune demyelination in Multiple Sclerosis (MS). However, the factors driving their development and MS susceptibility are obscure. We investigated how miRNAs, newly described as post-transcriptional regulators of gene expression, contribute to pathogenic T cell differentiation in MS. We profiled miRNA expression in naïve CD4+ T cells of healthy (n=8) and untreated MS (n=22) donors. miR-128, miR-27a/b and miR-340 were increased in naïve CD4+ T cells from MS patients. miR-128, -27a/b and -340 directly suppressed the pro-Th2 factor Bmi1, resulting in decreased GATA-3 expression. miR-340 additionally suppressed the Th2 cytokine IL-4. Overall, these miRNAs suppressed Th2 and enhanced pro-inflammatory Th1 responses. In addition, transfection of myelin-specific T cells with these miRNAs worsened EAE while treatment of MS patient cells with miRNA inhibitors led to the restoration of Th2 responses. These findings link miR-128, -27ab and -340 overexpression in MS patients’ naïve CD4+ T cells to the pro-inflammatory T cell differentiation observed in MS and illustrate the biological significance and therapeutic potential of these miRNAs.

A Harvard study recently reported in the Boston Globe might change the way we think about the cytoplasm. During cell movement, cytoplasm ‘flows’ like a liquid. However, a ‘liquid’ cell would be unable to maintain its structural integrity. This paradox is explained by the idea that the cytoskeleton undergoes a gel–sol transition, allowing the cell to have both fluid-like (sol) and more solid-like (gel) properties. The researchers coated 4.5-μm ferrimagnetic beads with RGD-containing peptides and bound them to the surface of various cell types through integrin receptors. Elastic and frictional properties of the cells were measured by shaking the beads using a magnetic field at increasing frequencies. The cells did not behave like a gel, which stiffens up suddenly, but stiffened gradually, like glassy materials. Thus, rather than thinking of the cytoskeleton as a gel, these observations suggest that it should be thought of as a ‘glassy material close to a glass transition, and that disorder and metastability may be essential features underlying its mechanical functions’. [See: Fabry, B. et al. (2001) Scaling the microrheology of living cells. Phys. Rev. Lett. 87, 148102.] S.L.

Most scientists are accustomed to a multinational workplace, as researchers increasingly travel abroad for experience and improved career prospects. This is the subject of a survey of US life scientists – ‘Working in a Multinational Laboratory’ – published in The Scientist (http://www.the-scientist.com/yr2001/oct/results_011001.html). The poll suggests that international participation in US academia is increasing, as homegrown scientists seek higher salaries in other sectors. Of 1153 researchers in respondents’ laboratories, only 50% were US born. Most overseas scientists come from China and India, with significant numbers from Japan, Russia, Germany and the UK. The survey also investigated the benefits and challenges of a multinational workplace. Overall, the reaction was extremely positive; respondents felt it benefited their research and also led to ‘great potlucks’. Non-US researchers enjoyed the resources available, and many expressed a desire to continue their careers in the USA. Worryingly, a few overseas researchers were paid less than their American counterparts and felt like second-class citizens, with fewer opportunities to move up the career ladder, causing a ‘raft of foreign-born scientists moving from lab to lab’. The greatest cultural bonding often occurs between members of different non-US nationalities. As a Harvard colleague once remarked: ‘before I came to the US I was a German, I am now a European’. S.L.

The Whitehead Institute of Biomedical Research announced that its new director will be the acclaimed molecular biologist Susan Lindquist. Previously based at the University of Chicago, Lindquist will become the third person to head the prestigious Institute, succeeding yeast biologist Gerald Fink and Nobel Laureate David Baltimore, making her one of the most influential women currently working in US science. Lindquist will use her position to help to support gender equality in science, which she says ‘most resoundingly isn't where it should be.’ Lindquist established her scientific reputation through work on protein folding, in diverse contexts including prion transmission, heredity and biomaterials, and is keen to promote the interdisciplinary nature of modern biomedical science ‘with physics, chemistry and biology all coming together’. She added: ‘When worlds collide, sparks fly, allowing us to take old problems and attack them in new ways.’ Founded by a wealthy benefactor, the Whitehead Institute is financially independent, but affiliated with the Massachusetts Institute of Technology (MIT). It has a reputation for top-quality, pioneering science through its work on the human genome project, cancer, AIDS and other areas. The appointment has met with acclaim and was described as ‘an inspired choice’ by MIT Provost Robert Brown. S.L.

In a landmark study, investigators from Yale and North Carolina State Universities report the simultaneous analysis of practically every protein encoded by the yeast genome [Zhu, H. et al. (2001) Science Express Reports 10.1126/science.1062191]. The group, led by Michael Snyder, made ‘proteome chips’ comprising microarrays of 5800 different proteins (93.5% of all yeast ORFs) and tested their ability to bind to various biomolecules. Using calmodulin as a probe, six previously known, and thirty-three novel, binding proteins were identified. However, four other calmodulin-binding proteins were not detected as they were present at very low levels on the chip. Interactions with various lipids were also tested and confirmed by independent techniques. By developing a high-throughput approach, the group was able to overcome the formidable obstacle of cloning, expressing and purifying a very large number of proteins. Similar methods should allow the preparation of arrays using the proteome of any organism whose genome has been sequenced. Some fine-tuning is necessary to ensure representation of specifically modified proteins and those that are poorly or improperly expressed. However, proteome chips are set to become a major new tool in biomedical research as they permit the screening of a comprehensive and defined set of proteins for a variety of activities, including posttranslational modifications and interactions with other proteins and pharmaceutical compounds. S.L.

A recent study has uncovered an astonishingly high level of misidentification of laboratory cell lines. Short tandem repeat (STR) profiling was used to examine 253 human cell lines and revealed that 36% were of a different type, or from a different species to that claimed. STR profiling is commonly used in forensic science and uses standard oligonucleotide primers to amplify polymorphic STR loci in the sample of interest. Automated analysis of the PCR products generates a numerical code specific for the sample. The authors suggest that STR profiling should provide the basis for an international reference standard for human cell lines and that all cell lines should be authenticated at the time they are being used [Masters J.R. et al. (2001) Proc. Natl. Acad. Sci. U. S. A. 98, 8012–8017]. The misidentification of cell lines might have been extremely costly in terms of wasted time, effort and money. First author John Masters of University College London, UK, describes the situation as a ‘scandal’, and UK newspaper The Observer claims that breast cancer cells have been mistakenly used in liver cancer research and that some colon cancer research has been carried out using cell lines from cervical tumours. However, with the mandatory testing of cell lines, which costs about $200 per sample, this problem could quickly be minimized, assuring the quality of published data. S.L.

The rivalry between the public and privately funded human genome sequencing projects was set aside on 6 June as scientists from the two teams got together in Chevy Chase, Maryland. The goal of the meeting, according to Chad Nussbaum of the Whitehead Institute, was to find the cheapest strategy that can also make sense of a previously unexplored genome. Press reports state that the meeting was conducted in a calm, amicable manner. The groups agreed that both approaches had been useful in sequencing the human genome, and that the best way forward for future projects would depend on the complexity of the genome being studied and would benefit greatly from more advanced computer software. Two of the main protagonists, Eric Lander and Craig Venter, were not present, and the promise of a paper by Lander critical of Celera's approach indicates that hostilities might soon recommence (see Science magazine 15 June 2001, p. 292 for further details). Meanwhile, estimates of the number of genes in the human sequence still vary widely. Bill Haseltine, CEO of Human Genome Sciences (HGS), described in the Financial Times as a ‘maverick’, has suggested that there might be as many as 100 000 human genes, despite the fact that most estimates are around 30 000. Haseltine claims that HGS has already identified 60 000 genes through analysis of mRNA transcripts. S.L.