Dmitry Bandura

Mass cytometry: technique for real time single cell multitarget immunoassay based on inductively coupled plasma time-of-flight mass spectrometry.

A novel instrument for real time analysis of individual biological cells or other microparticles is described. The instrument is based on inductively coupled plasma time-of-flight mass spectrometry and comprises a three-aperture plasma-vacuum interface, a dc quadrupole turning optics for decoupling ions from neutral components, an rf quadrupole ion guide discriminating against low-mass dominant plasma ions, a point-to-parallel focusing dc quadrupole doublet, an orthogonal acceleration reflectron analyzer, a discrete dynode fast ion detector, and an 8-bit 1 GHz digitizer. A high spectrum generation frequency of 76.8 kHz provides capability for collecting multiple spectra from each particle-induced transient ion cloud, typically of 200-300 micros duration. It is shown that the transients can be resolved and characterized individually at a peak frequency of 1100 particles per second. Design considerations and optimization data are presented. The figures of merit of the instrument are measured under standard inductively coupled plasma (ICP) operating conditions (<3% cerium oxide ratio). At mass resolution (full width at half-maximum) M/DeltaM > 900 for m/z = 159, the sensitivity with a standard sample introduction system of >1.4 x 10(8) ion counts per second per mg L(-1) of Tb and an abundance sensitivity of (6 x 10(-4))-(1.4 x 10(-3)) (trailing and leading masses, respectively) are shown. The mass range (m/z = 125-215) and abundance sensitivity are sufficient for elemental immunoassay with up to 60 distinct available elemental tags. When <15 elemental tags are used, a higher sensitivity mode at lower resolution (M/DeltaM > 500) can be used, which provides >2.4 x 10(8) cps per mg L(-1) of Tb, at (1.5 x 10(-3))-(5.0 x 10(-3)) abundance sensitivity. The real-time simultaneous detection of multiple isotopes from individual 1.8 microm polystyrene beads labeled with lanthanides is shown. A real time single cell 20 antigen expression assay of model cell lines and leukemia patient samples immuno-labeled with lanthanide-tagged antibodies is presented.

Study of Cell Antigens and Intracellular DNA by Identification of Element-Containing Labels and Metallointercalators Using Inductively Coupled Plasma Mass Spectrometry

The enumeration of absolute cell numbers and cell proliferation in clinical samples is important for diagnostic and research purposes. Detection of cellular DNA with fluorescent dyes is the most commonly used approach for cell enumeration in cytometry. Inductively coupled plasma mass spectrometry (ICPMS) has been recently introduced to the field of protein and cell surface antigen identification via ICPMS-linked immunoassays using element-labeled affinity reagents such as gold and lanthanide-conjugated antibodies. In the present work, we describe novel methods for using metallointercalators that irreversibly bind DNA and low concentrations of rare earth metals added to cell growth media for rapid and sensitive measurement of cell numbers by mass spectrometry. We show that Ir- and Rh-containing metallointercalators are useful reagents for labeling cells and normalizing signals when studying antigen expression on different types and numbers of cells. Results are presented for solution analysis performed by conventional ICPMS and compared to measurements obtained on the novel flow cytometer mass spectrometer (FC-MS) instrument, designed to analyze multiple antigens and DNA simultaneously in single cells.

Flow cytometer with mass spectrometer detection for massively multiplexed single-cell biomarker assay

This paper describes the development and application of new metal-tagging reagents and a novel mass spectrometer (MS) detector for a flow cytometer that enables highly multiplexed measurement of many biomarkers in individual cells. A new class of tagging reagents, based on an acrylic polymer backbone that incorporates a reproducible number of lanthanide elements, has been developed. When linked to antibodies that specifically recognize target proteins of interest, determination of the tag elements is diagnostic for the presence and quantification of the antigen. The use of enriched stable isotope tags provides the opportunity for multiparametric assay. The new instrument uses inductively coupled plasma (ICP) to vaporize, atomize, and ionize individual cells that have been probed using the metal-labeled antibodies. The elemental composition, specifically of the metal tags, is recorded simultaneously using a time-of-flight (TOF)-MS that has been specifically designed for high-speed analysis during the short transient corresponding to the individual cell event. The detector provides for well-resolved atomic fingerprints of many elemental and isotopic tags, with little overlap of neighboring signals (high abundance sensitivity) and wide dynamic range both for a single antigen and between antigens.

Lanthanide-containing polymer microspheres by multiple-stage dispersion polymerization for highly multiplexed bioassays

We describe the synthesis and characterization of metal-encoded polystyrene microspheres by multiple-stage dispersion polymerization with diameters on the order of 2 mum and a very narrow size distribution. Different lanthanides were loaded into these microspheres through the addition of a mixture of lanthanide salts (LnCl(3)) and excess acrylic acid (AA) or acetoacetylethyl methacrylate (AAEM) dissolved in ethanol to the reaction after about 10% conversion of styrene, that is, well after the particle nucleation stage was complete. Individual microspheres contain ca. 10(6)-10(8) chelated lanthanide ions, of either a single element or a mixture of elements. These microspheres were characterized one-by-one utilizing a novel mass cytometer with an inductively coupled plasma (ICP) ionization source and time-of-flight (TOF) mass spectrometry detection. Microspheres containing a range of different metals at different levels of concentration were synthesized to meet the requirements of binary encoding and enumeration encoding protocols. With four different metals at five levels of concentration, we could achieve a variability of 624, and the strategy we report should allow one to obtain much larger variability. To demonstrate the usefulness of element-encoded beads for highly multiplexed immunoassays, we carried out a proof-of-principle model bioassay involving conjugation of mouse IgG to the surface of La and Tm containing particles and its detection by an antimouse IgG bearing a metal-chelating polymer with Pr.

An introduction to mass cytometry: fundamentals and applications.

Mass cytometry addresses the analytical challenges of polychromatic flow cytometry by using metal atoms as tags rather than fluorophores and atomic mass spectrometry as the detector rather than photon optics. The many available enriched stable isotopes of the transition elements can provide up to 100 distinguishable reporting tags, which can be measured simultaneously because of the essential independence of detection provided by the mass spectrometer. We discuss the adaptation of traditional inductively coupled plasma mass spectrometry to cytometry applications. We focus on the generation of cytometry-compatible data and on approaches to unsupervised multivariate clustering analysis. Finally, we provide a high-level review of some recent benchmark reports that highlight the potential for massively multi-parameter mass cytometry.

The potential for elemental analysis in biotechnology

The ICP-MS brings particular attributes to the method that distinguishes it from organic mass spectrometry: relative insensitivity to concomitant organic or metallic species, equivalent sensitivity to all similarly-tagged complexes, inherent ability to provide absolute quantitation and linearity of response. All these positive features fit the requirements of modern-day biotechnology. In this work, the potential of ICP-MS is discussed in the context of several urgent problems of biotechnology including: the determination of the state of phosphorylation of proteins, quality control of biologically active materials and control of efficiency of cell line transfections.

Characterization of phosphorus content of biological samples by ICP-DRC-MS: potential tool for cancer research

Phosphorus and sulfur are detected as phosphorus oxide and sulfur oxide ions (PO+ and SO+), produced by oxidation reactions with O2 performed in the reaction cell of the inductively coupled plasma dynamic reaction cell mass spectrometer (ICP-DRC-MS), at sub-ng mL−1 detection limits. This allows pM mL−1 detection of phospho-proteins, with S used as an internal standard (see ref. 9). The method was applied to digests (in HCl) of in-vitro tyrosine kinase assays, both as an evaluation of kinase autophosphorylation and phosphorylation of substrate. Detecting the phosphorus/sulfur ratio (via measured PO+/SO+) in cell cultures is shown to provide a distinguishable difference between malignant cell lines and primary cultures. The PO+/SO+ ratio for human colorectal adenocarcinoma (CRC) tissue samples compared with matched normal (N) tissue samples from the same patients is shown to be higher, at (PO+/SO+)CRC/(PO+/SO+)N = 1.75 ± 0.18 (n = 4). Samples used in this analysis were of needle biopsy amounts (0.2–0.5 mg), with a greater than 70% tumor burden in CRC. The phospho-protein phosvitin is detected directly from dried one-dimensional polyacrylamide gels using laser ablation ICP-MS by detecting phosphorus at sub-nM amounts. The phosphorus detection limit for direct ablation, assessed from ablating gel doped with P and blank gel, is 0.6 µg g−1 in gel. Direct detection of sulfur from the gels is obscured by the high sulfur background for the blank gels, which is attributed to the sulfur-containing catalysts used in polymerization and to sodium dodecyl sulfate (SDS) used for protein denaturing.

Inductively coupled plasma mass spectrometer with axial field in a quadrupole reaction cell

A novel reaction cell for ICP-MS with an electric field provided inside the quadrupole along its axis is described. The field is implemented via a DC bias applied to additional auxiliary electrodes inserted between the rods of the quadrupole. The field reduces the settling time of the pressurized quadrupole when its mass bandpass is dynamically tuned. It also improves the transmission of analyte ions. It is shown that for the pressurized cell with the field activated, the recovery time for a change in quadrupole operating parameters is reduced to <4 ms, which allows fast tuning of the mass bandpass in concert with and at the speed of the analyzing quadrupole. When the cell is operated with ammonia, the field reduces ion-ammonia cluster formation, further enhancing the transmission of atomic ions that have a high cluster formation rate. Ni·(NH3)n+ cluster formation in a cell operated with a wide bandpass (i.e., Ni+ precursors are stable in the cell) is shown to be dependent on the axial field strength. Clusters at n = 2–4 can be suppressed by 9, 1200, and >610 times, respectively. The use of a retarding axial field for in-situ energy discrimination against cluster and polyatomic ions is shown. When the cell is pressurized with O2 for suppression of 129Xe+, the formation of 127IH2+ by reactions with gas impurities limits the detection of 129I to isotopic abundance of ∼10−6. In-cell energy discrimination against 127IH2+ utilizing a retarding axial field is shown to reduce the abundance of the background at m/z = 129 to ca. 3 × 10+ of the 127I+ signal. In-cell energy discrimination against 127IH2+ is shown to cause less I+ loss than a post-cell potential energy barrier for the same degree of 127IH2+ suppression.

Bio-Functional, Lanthanide-Labeled Polymer Particles by Seeded Emulsion Polymerization and their Characterization by Novel ICP-MS Detection

We present the synthesis and characterization of monodisperse, sub-micron poly(styrene) (PS) particles loaded with up to and including 10(7) lanthanide (Ln) ions per particle. These particles have been synthesized by seeded emulsion polymerization with a mixture of monomer and a pre-formed Ln complex, and analyzed on a particle-by-particle basis by a unique inductively coupled plasma mass cytometer. Seed particles were prepared by surfactant-free emulsion polymerization (SFEP) to obtain large particle sizes in aqueous media. Extensive surface acid functionality was introduced using the acid-functional initiator ACVA, either during seed latex synthesis or in the second stage of polymerization. The loading of particles with three different Ln ions (Eu, Tb, and Ho) has proven to be close to 100 % efficient on an individual and combined basis. Covalent attachment of metal-tagged peptides and proteins such as Neutravidin to the particle surface was shown to be successful and the number of bound species can be readily determined. We believe these particles can serve as precursors for multiplexed, bead-based bio-assays utilizing mass cytometric detection.

Messenger RNA Detection in Leukemia Cell lines by Novel Metal-Tagged in situ Hybridization using Inductively Coupled Plasma Mass Spectrometry

Conventional gene expression profiling relies on using fluorescent detection of hybridized probes. Physical characteristics of fluorophores impose limitations on achieving a highly multiplex gene analysis of single cells. Our work demonstrates the feasibility of using metal-tagged in situ hybridization for mRNA detection by inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS as an analytical detector has a number of unique and relevant properties: 1) metals and their stable isotopes generate non-overlapping distinct signals that can be detected simultaneously; 2) these signals can be measured over a wide dynamic range; 3) ICP-MS is quantitative and very sensitive. We used commercial antibodies conjugated to europium (Eu) and gold together with biotinylated oligonucleotide probes reacted with terbium-labeled streptavidin to demonstrate simultaneous mRNA and protein detection by ICP-MS in leukemia cells.Urokinase-type plasminogen activator (uPA) is associated with cancer recurrence where the most evidence comes from studies in breast cancer. According to the European Organization for Research and Treatment of Cancer, uPA is considered one of the most prominent biomarkers for cancer recurrence and therefore new agents are needed to inhibit it. Whether uPA is also expressed in pediatric cancers is yet unknown. If it is then uPA inhibitors might also help children with recurrent cancers. In this study, we addressed whether the integrin-linked kinase inhibitor (ILK), QLT0267, could suppress uPA. We previously showed that uPA expression is maximally inhibited when both the Akt and MAP kinase pathways were blocked which we anticipated can be achieved via QLT0267. In MDA-MB-231 breast cancer cells, QLT0267 blocked signaling through Akt and MAP kinase with a correlative decrease in uPA protein and mRNA, which corresponded to an inhibition of c-Jun phosphorylation. Consistent with these findings, cellular invasion was inhibited with either QLT0267 or with small interfering RNA against ILK. We then questioned whether uPA was commonly expressed in childhood sarcomas and if QLT0267 might be effective in this setting. We determined for the first time that uPA was highly expressed in rhabdomyosarcomas (RMS), but not Ewings sarcomas by screening cell lines (n = 31) and patient samples (n = 200) using Affymetrix microarrays. In alveolar RMS (ARMS) cell lines, QLT0267 blocked cell signaling, uPA production, invasion and ultimately survival. We concluded that QLT0267 blocks the production of uPA providing a new target for the management of recurrent cancers.There is a growing body of literature suggesting that signaling based therapy might be a potential approach for medullary thyroid cancer (MTC). In this review we focus on the tumor suppressor role of Notch1 and Raf-1 signaling in MTC. Interestingly these two pathways are minimally active or absent in these tumors and activation of Notch1 and Raf-1 significantly reduces tumor growth in vitro. Therefore, identification of compounds that induce these pathways could be a potential strategy to treat patients with MTC.In the last two decades there has been considerable progress in our understanding of the role of sphingolipids in controlling signal transduction processes, particularly in the mechanisms leading to regulation of cell growth and death. Ceramide is a well-characterized sphingolipid metabolite and second messenger that can be produced by cancer cells in response to a variety of stimuli, including therapeutic drugs, leading to cell cycle arrest and apoptosis. Although this is a promising aspect when thinking of treating cancer, it should be borne in mind that ceramide production may not always be a growth inhibitory or pro-apoptotic signal. In fact, ceramide can be readily converted to sphingosine 1-phosphate (S1P) by the concerted actions of ceramidases and sphingosine kinases, or to ceramide 1-phosphate (C1P) by the action of ceramide kinase. In general, S1P and C1P have opposing effects to ceramide, acting as pro-survival or mitogenic signals in most cell types. This review will address our current understanding of the many roles of ceramide, S1P and C1P in the regulation of cell growth and survival with special emphasis to the emerging role of these molecules and their metabolizing enzymes in controlling tumor progression and metastasis.The Y-box Binding Protein-1 (YB-1) is a highly conserved oncogenic transcription/translation factor that is expressed in cancers affecting adults and children. It is now believed that YB-1 plays a causal role in the development of cancer given recent work showing that its expression drives the tumorigenesis in the mammary gland. In human breast cancers, YB-1 is associated with rapidly proliferating tumors that are highly aggressive. Moreover, expression of YB-1 promotes the growth of breast cancer cell lines both in monolayer and anchorage independent conditions. The involvement of YB-1 in breast cancer pathogenesis has made it a putative therapeutic target; however, the mechanism(s) that regulate YB-1 are poorly understood. This review first describes the oncogenic properties of YB-1 in cancer. It also highlights the importance of YB-1 in hardwiring signal transduction pathways to the regulation of genes involved in the development of cancer.Specific combinations of transcription-factor binding sites in the promoter regions of genes regulate gene expression, and thus key functional processes in cells. Analysis of such promoter regions in specific functional contexts can be used to delineate novel disease-associated genes based on shared phenotypic properties. The aim of this study was to utilize promoter analysis to predict cell proliferation-associated genes and to test this method in colon cancer cell lines. We used freely-available bioinformatic techniques to identify cell-proliferation-associated genes expressed in colon cancer, extract a shared promoter module, and identify novel genes that also contain this module in the human genome. An EGRF/ETSF promoter module was identified as prevalent in proliferation-associated genes from a colon cancer cDNA library. We detected 30 other genes, from the known promoters of the human genome, which contained this proliferation-associated module. This group included known proliferation-associated genes, such as HERG1 and MCM7, and a number of genes not previously implicated in cell proliferation in cancer, such as TSPAN3, Necdin and APLP2. Suppression of TSPAN3 and APLP2 by siRNA was performed and confirmed by RT-PCR. Inhibition of these genes significantly inhibited cell proliferation in colon cancer cell lines. This study demonstrates that promoter analysis can be used to identify novel cancer-associated genes based on shared functional processes.Background: Potassium bromate (KBrO3), used in both the food and cosmetics industry, and a drinking water disinfection by-product, is a nephrotoxic compound and rodent carcinogen. To gain insight into the carcinogenic mechanism of action and provide possible biomarkers of KBrO3 exposure, the gene expression in kidneys from chronically exposed male F344 rats was investigated. Methods: Male F344 rats were exposed to KBrO3 in drinking water for 52 and 100 wk. Kidneys were removed, frozen, and stored at −80°C, then used for Affymetrix microarray analysis. Gene expression patterns were examined using a non-carcinogenic (20 ppm) and carcinogenic dose (400 ppm) at 52 wk, and compared to 100 wk high dose (400 ppm) and adenoma gene expression. Results: Statistical analysis revealed 144, 224, 43, and 994 genes out of 15866 from the 52 wk low, 52 wk high, 100 wk high, and adenomas respectively, were differentially expressed when compared to control kidneys. Gene ontology classification of the 52 wk high dose showed alterations of gene transcripts involved in oxidative stress, lipid metabolism, kidney function/ion transport, and cellular function. In a comparison of kidney development gene expression, alterations were seen in the adenomas but not in the 52 wk bromate-treated kidneys. However, the normal kidney from the high dose group resembled the adenoma expression pattern with early kidney development genes being up-regulated and adult phase genes being down-regulated. Moreover, eight genes were identified which could serve as biomarkers of carcinogenic exposure to bromate. The most promising of these was Pendrin, or Slc26a4, a solute carrier of chloride and iodide active in the kidney, thyroid, and inner ear. All these tissues are targets of KBrO3 toxicity. Expression array results were verified with quantitative real-time rtPCR. Conclusions: These data demonstrate that the 400 ppm carcinogenic dose of KBrO3 showed marked gene expression differences from the 20 ppm non-carcinogenic dose. Comparison of kidney development gene expression showed that the adenoma patterns were more characteristic of embryonic than adult kidneys, and that the normal kidney from the high dose group resembled the adenoma-like gene expression pattern. Taken together, the analysis from this study identifies potential biomarkers of exposure and illuminates a possible carcinogenic mode of action for KBrO3.Chronic eosinophilic leukemia is a clonal disease characterized by hypereosinophilia and eosinophilia-related pathologic manifestations. Recently, the fusion gene FIP1L1/PDGFRA was found in the long arm of chromosome 4 and its expression has been shown to be associated with development of a clinical hypereosinophilic syndrome (HES) in a significant proportion of patients. FIP1L1/PDGFRα, the product of the gene FIP1L1/PDGFRA, is a constitutively activated tyrosine kinase and can be inhibited by imatinib mesylate. Several investigations have tried to dissect the mechanism of leukemogenesis and signaling induced by FIP1L1/PDGFRα in cell lines, primary human eosinophils and in murine myeloproliferative models. In this review, we analyzed the current knowledge on the relationship between FIP1L1/PDGFRα-induced signaling and eosinophil proliferation, survival and activation, specially focusing on its possible role in the modulation of cytokine and chemoattractant signaling pathways.The increasing number of proteomic and DNA-microarray studies is continually providing a steady acquisition of data on the molecular abnormalities associated with human tumors. Rapid translation of this accumulating biological information into better diagnostics and more effective cancer therapeutics in the clinic depends on the use of robust function-testing strategies. Such strategies should allow identification of molecular lesions that are essential for the maintenance of the transformed phenotype and enable validation of potential drug-targets. The tetracycline regulated gene expression/ suppression systems (Tet-systems) developed and optimized by bioengineers over recent years seem to be very well suited for the function-testing purposes in cancer research. We review the history and latest improvements in Tet-technology in the context of functional oncogenomics.Multiple lines of evidence implicate over-expression and activation of the androgen receptor (AR) in the progression of prostate cancer (PC) to androgen-independence (AI) and resistance to therapy. The mechanisms leading to AR over-expression are not fully understood but binding of Sp1 to specific Sp1-binding sites in the AR promoter and 5′-untranslated region (5′-UTR) was shown to up-regulate AR transcription. In this work, we further characterized the role of Sp1 in the control of AR transcription and explored its potential as a therapeutic target in androgen-dependent (AD) and independent (AI) LNCaP cells. We identified a pair of new Sp1-binding site in the 5′-UTR of AR which we named ARSp1-3. ARSp1-3 binds Sp1 with higher affinity than other known Sp1-binding sites in the promoter/5′-UTR and in transfection experiments, the ARSp1-3 reporter showed higher transcriptional activity in AI than in AD cells. Treatment of these cells with nanomolar concentrations of Mithramycin inhibited binding of Sp1 to its binding sites in the promoter/5′-UTR of the AR gene but more specifically the binding of ARSp1-3 while other regulatory elements of the AR promoter were not affected. Inhibition of Sp1 binding by Mithramycin decreased the AR transcription and transactivation of PSA reporter constructs. At the lowest concentrations, Mithramycin decreased endogenous AR protein and proliferation of AD and AI LNCaP cells. The combinations of Mithramycin with either paclitaxel or bicalutamide were highly synergistic. Conclusion: Sp1 binding induces AR transcription in LNCaP cells. The higher affinity of ARSp1-3 for Sp1 may support higher AR mRNA levels in AI than AD LNCaP cells. Mithramycin is a potent and specific inhibitor of Sp1 and AR transcription with potential, at very low concentrations, to enhance the efficacy of hormones or taxane based therapy in patients with recurrent or androgen-independent progression that sustain AR expression.Many tumor markers for bladder cancer have been evaluated for use in detecting and monitoring bladder cancers tissue specimens, bladder washes, and urine specimens. However, none of the biomarkers reported to date has shown sufficient sensitivity and specificity to detect the entire spectrum of bladder cancers in routine clinical practice. The limited value of the established prognostic markers demands analysis of new molecular parameters having the potential to predict the prognosis of bladder cancer patients, particularly, the high-risk patients at risk of cancer progression and recurrence. Abnormal methylation of CpG islands can efficiently repress transcription of the associated gene in a manner akin to mutations and deletions. Several tumor suppressor genes correlated with bladder cancer contain CpG islands in their promoters. Markers for aberrant methylation may be a potential gateway for monitoring bladder cancer. Hypermethylation of several gene promoters was detected in urine sediment DNA from bladder cancer patients. Detection of DNA methylation in voided urine is feasible and noninvasive. Methylation is an important molecular mechanism in the development of bladder cancer and could be used as a prognostic and diagnostic marker. Aberrant patterns of epigenetic modification could, in the near future, be crucial indicators in cancer diagnosis, prognosis, and may additionally be good targets for developing novel therapies while maintaining quality of life.In 1911 Peyton Rous described a transmissible agent that could induce sarcoma in chicken, this was later identifi ed as a virus and named Rous Sarcoma Virus (Rous, 1911). Identifi cation of the viral tyrosine kinase v-Src and its cellular counterpart c-Src (later in the text referred as Src), introduced the concept of proto-oncogene which has had a signifi cant impact on the progress of our knowledge of carcinogenesis (Martin, 2001). Since its description, Src has been implicated in a variety of malignancies (Frame, 2002) including prostate cancer (Chang et al. 2007), which is the most commonly diagnosed cancer in men and the second leading cause of cancer-related death in men in the U.K. and U.S. (Jemal et al. 2007). The Src-family kinases (SFK) comprises of nine members including Src, Fyn, Yes, Blk, Yrk, Fgr, Hck, Lck and Lyn; Src, Fyn and Yes being ubiquitously expressed in all cells while other kinases are tissue specifi c. Apart from Src, two other family members, Fgr (Edwards et al. 2003) and Lyn (Goldenberg-Furmanov et al. 2004) have been implicated in prostate cancer. All SFK members share similar structure; each protein consists of four Src homology (SH) domains and a unique amino-terminal domain. High resolution crystallographic analysis of Src revealed the complex nature of structural changes involved in switching between active and inactive state. Src can be locked in an inactive conformation when its negative regulatory tail is phosphorylated at tyrosine Y530 by c-terminal Src kinase (Csk). However, when Src becomes autophosphorylated at tyrosine Y419, which is located in the kinase domain, the protein unfolds assuming its catalytically active conformation. Apart from being a tyrosine kinase, Src may function as a scaffolding molecule being an adaptor for other intracellular proteins that in turn can activate Src by the release of its intramolecular bonds. Another mechanism of Src activation, called peripheral targeting, involves translocation of inactive Src, which is located in the perinuclear region, to the cell periphery where Src becomes attached to the inner surface of cell membrane by its myristoylation fragment (Frame, 2002).Src interacts with a wide variety of proteins including receptor tyrosine kinases, G-protein coupled receptors, steroid receptors, integrins, other non-receptor protein kinases etc., which is re fl ected in the multiplicity of resulting cellular biological events (Thomas and Brugge, 1997). Crosstalk between Src and the components of PI3K (phosphatidylinositol 3-kinase) and MAPK (mitogen activated protein kinase) pathways may affect tumor cell proliferation and apoptosis while involvement in focal adhesion complexes, especially FAK (focal adhesion kinase), paxillin and p130CAS (p130 Crk-associate sub-strate) plays an important part in promoting cell adhesion, migration and invasion (Summy and Gallick, 2006). Considering its unique position at the crossroads of the intracellular signaling networks, Src has become an attractive target in the search of novel prostate cancer therapies (McCarty, 2004).The oncogene MCTS1, discovered as an amplified product in a subset of T-cell lymphoma lines, has been implicated in cell cycle progression and conferring a growth advantage in lymphomas and breast cancer. Recent research shows that it modulates the MAPK pathway and acts as a translational activator both in vivo and in vitro. In breast cancer cells, expression of MCTS1 confers aggressive properties and inhibits apoptosis. This article will review these data and its implications on our understanding of cancer.