Expression of focal adhesion kinase in acute myeloid leukemia is associated with enhanced blast migration, increased cellularity, and poor prognosis

Activation of FAK/PI3K/Rac1 signaling controls actin reorganization and inhibits cell motility in human cancer cells

We have recently identified a specific signaling pathway that regulates actin reorganization in malignant human breast and prostate epithelial cells associated with FAK, PI-3K and Rac1 activation. Here we report that this pathway operates in MCF7 cells upon activation of membrane androgen receptors (mAR). Stimulation of mAR by the non-permeable testosterone-BSA conjugate resulted in early actin reorganization documented by quantitative measurements of actin dynamics and morphological analysis of microfilament organization. This effect was regulated by early phosphorylation of FAK and subsequent PI-3K and Rac1 activation. The functional role of this pathway was further shown in A375 melanoma cells. Treatment with the opioid antagonist alpha(s1) casomorphin resulted in rapid and potent actin remodeling in A375 cells, regulated by rapid activation of the FAK/PI-3K/Rac1 signaling. Pretreatment of both cell lines with the specific PI-3K inhibitor wortmannin blocked actin reorganization. Interestingly, wound healing assays revealed that testosterone-BSA and alpha (s1) casomorphin significantly inhibited MCF7 and A375 cell motility respectively. These effects were abrogated through blockade of PI-3K signaling by wortmannin. The results presented here indicate that actin reorganization through FAK/PI3-K/Rac-1 activation operates in various human cancer cell systems supporting a functional role for FAK/PI-3K/Rac1/actin signaling in controlling cell motility.

Inhibition of cell motility by troglitazone in human ovarian carcinoma cell line

Background

Troglitazone (TGZ) is a potential anticancer agent. Little is known about the effect of this agent on cancer cell migration.

Methods

Human ovarian carcinoma cell line, ES-2 cells were treated with various concentrations of TGZ. Cell migration was evaluated by wound-healing and Boyden chamber transwell experiments. PPARγ expression was blocked by PPARγ small interfering RNA. The effects of TGZ on phosphorylation of FAK, PTEN, Akt were assessed by immunoblotting using phospho-specific antibodies. The cellular distribution of paxillin, vinculin, stress fiber and PTEN was assessed by immunocytochemistry.

Results

TGZ dose- and time-dependently impaired cell migration through a PPARγ independent manner. TGZ treatment impaired cell spreading, stress fiber formation, tyrosine phosphorylation of focal adhesion kinase (FAK), and focal adhesion assembly in cells grown on fibronectin substratum. TGZ also dose- and time-dependently suppressed FAK autophosphorylation and phosphorylation of the C-terminal of PTEN (a phosphatase). At concentration higher than 10 μM, TGZ caused accumulation of PTEN in plasma membrane, a sign of PTEN activation.

Conclusion

These results indicate that TGZ can suppress cultured ES-2 cells migration. Our data suggest that the anti-migration potential of TGZ involves in regulations of FAK and PTEN activity.

Overexpression of focal adhesion kinase in head and neck squamous cell carcinoma is independent of fak gene copy number

The development of human malignancies can involve the aberrant regulation of intracellular signal transduction pathways that regulate cell-extracellular matrix interactions.

PURPOSE

In the current study, we aimed to evaluate focal adhesion kinase (FAK) at both genetic and protein expression levels in head and neck squamous cell carcinomas (HNSCC) and to explore the prognostic significance of FAK.

EXPERIMENTAL DESIGN

A total of 211 tissue specimens, including 147 primary tumors, 56 lymph node metastases, 3 benign hyperplasias, and 5 dysplasias, were analyzed using immunohistochemistry. The fak gene dosage was determined in 33 tumors. Correlations among DNA, protein, and clinicopathologic variables were analyzed.

RESULTS

FAK protein was overexpressed in HNSCCs compared with corresponding normal mucosa. High expression levels were found in 62% of the samples. Positive immunostaining was also detected in benign hyperplasias and preinvasive dysplastic lesions. All lymph node metastases examined showed FAK overexpression, with significant correlation with the expression in matched primary tumor. DNA copy number ratios for fak were higher in 39% of the tumors compared with normal mucosa. However, elevated FAK expression did not correlate with gains on DNA level, and not all cases with an amplification of the fak gene displayed protein overexpression. Similar data were obtained in five HNSCC-derived cell lines, in which FAK mRNA levels were precisely correlated with FAK protein levels. FAK protein overexpression in tumors correlated with nodal metastases.

CONCLUSIONS

These findings suggest an involvement of FAK in the onset and progression of HNSCC and provide an insight into a mechanism of FAK activation alternative to gene amplification.

Focal adhesion kinase: a promising target for anticancer therapy

Focal adhesion kinase (FAK) is a protein tyrosine kinase acting as an early modulator of the integrin signalling cascade, thus regulating various basic cellular functions. In transformed cells, upregulation of FAK protein expression and uncontroled signalling were held responsible for the promotion of malignant phenotypic characteristics, as well as resistance to chemotherapy and radiotherapy. Direct FAK targeting resulted in the inhibition of the malignant phenotype of cancer cells, whereas increased apoptotic rates of cancer cells, either used alone or in combination with conventional chemotherapeutic agents, radiotherapy or hormonal therapy. Furthermore, drugs used in cancer chemotherapy, besides their basic mode of action, were also shown to act through altering FAK signalling. Finally, positive results were noted by the transfection of cancer cells with fak mutants or genes that suppress FAK expression or activity, such as phosphatase and tensin homolog deleted on chromosome Ten (PTEN), ribonucleotide reductase M1 polypeptide (RRM1) and melanoma differentiation-associated gene-7 (mda-7). The purpose of this article is a comprehensive review of the existing data on the possible use of FAK targeting in anticancer therapy.

Focal adhesion kinase is required for CXCL12-induced chemotactic and pro-adhesive responses in hematopoietic precursor cells

Hematopoietic stem/progenitor cells (HSC/P) reside in the bone marrow in distinct anatomic locations (niches) to receive growth, survival and differentiation signals. HSC/P localization and migration between niches depend on cell-cell and cell-matrix interactions, which result from the cooperation of cytokines, chemokines and adhesion molecules. The CXCL12-CXCR4 pathway, in particular, is essential for myelopoiesis and B lymphopoiesis but the molecular mechanisms of CXCL12 action remain unclear. We previously noted a strong correlation between prolonged CXCL12-mediated focal adhesion kinase (FAK) phosphorylation and sustained pro-adhesive responses in progenitor B cells, but not in mature B cells. Although FAK has been well studied in adherent fibroblasts, its function in hematopoietic cells is not defined. We used two independent approaches to reduce FAK expression in (human and mouse) progenitor cells. RNA interference (RNAi)-mediated FAK silencing abolished CXCL12-induced responses in human pro-B leukemia, REH cells. FAK-deficient REH cells also demonstrated reduced CXCL12-induced activation of the GTPase Rap1, suggesting the importance of FAK in CXCL12-mediated integrin activation. Moreover, in FAK(flox/flox) hematopoietic precursor cells, Cre-mediated FAK deletion resulted in impaired CXCL12-induced chemotaxis. These studies suggest that FAK may function as a key intermediary in signaling pathways controlling hematopoietic cell lodgment and lineage development.

RNAi-mediated knockdown of target genes: a promising strategy for pancreatic cancer research

Pancreatic cancer is one of the most aggressive malignancies with a very poor prognosis, partially due to its very low accessibility to resection and resistance to chemoradiotherapy. As such, it is reasonable to find more effective, specific therapies and the related therapeutic targets. The identification of certain genes contributing to the tumorigenesis and poor prognosis provides the specific targets for efficient silencing by RNA interference (RNAi). As a powerful tool to suppress gene expression in mammalian cells, RNAi can be directed against pancreatic cancer through various pathways, including the inhibition of overexpressed oncogenes, suppression of tumor growth, metastasis and enhancement of apoptosis. In combination with chemoradiotherapy agents, RNAi can also attenuate the chemoradiation resistance of pancreatic cancer. In addition, RNAi has been used to define the 'loss of function' of endogenous genes in pancreatic cancer. This review provides a brief introduction to recent developments of RNAi applications in pancreatic cancer studies and suggestions for further exploration. It substantially demonstrates that RNAi holds a promising therapeutic potential as a future treatment for pancreatic cancer.

VEGFR-1 (FLT-1), beta1 integrin, and hERG K+ channel for a macromolecular signaling complex in acute myeloid leukemia: role in cell migration and clinical outcome

Leukemia cell motility and transendothelial migration into extramedullary sites are regulated by angiogenic factors and are considered unfavorable prognostic factors in acute leukemias. We have studied cross talk among (1) the vascular endothelial growth factor receptor-1, FLT-1; (2) the human eag-related gene 1 (hERG1) K(+) channels; and (3) integrin receptors in acute myeloid leukemia (AML) cells. FLT-1, hERG1, and the beta(1) integrin were found to form a macromolecular signaling complex. The latter mostly recruited the hERG1B isoform of hERG1 channels, and its assembly was necessary for FLT-1 signaling activation and AML cell migration. Both effects were inhibited when hERG1 channels were specifically blocked. A FLT-1/hERG1/beta(1) complex was also observed in primary AML blasts, obtained from a population of human patients. The co-expression of FLT-1 and hERG1 conferred a pro-migratory phenotype to AML blasts. Such a phenotype was also observed in vivo. The hERG1-positive blasts were more efficient in invading the peripheral circulation and the extramedullary sites after engraftment into immunodeficient mice. Moreover, hERG1 expression in leukemia patients correlated with a higher probability of relapse and shorter survival periods. We conclude that in AML, hERG1 channels mediate the FLT-1-dependent cell migration and invasion, and hence confer a greater malignancy.

Photodynamic therapy suppresses the migration and invasion of head and neck cancer cells in vitro

Head and neck cancer is highly invasive. It has a tendency to metastasise to regional or distant sites after incomplete treatment. Photodynamic therapy (PDT) is effective in the treatment of head and neck cancers. To investigate the effect of sublethal PDT on the invasiveness of head and neck cancer cells and to elucidate the possible mechanisms, we initiated this study. Two head and neck cancer cell lines, KJ-1 and Ca9-22, were used in this study. Wound healing assay, migration assay, and matrigel invasion assay were used to evaluate the cell migration and invasion. Immunoblotting was performed to investigate the possibly involved signaling pathways. Sublethal PDT significantly suppressed the migration and invasion of both KJ-1 and Ca9-22 cells. Phosphorylation of the focal adhesion kinase (FAK) and its down-stream Src kinase and extracellular signal-regulated kinase (ERK) were also inhibited after sublethal PDT. Sublethal PDT suppresses the migration and invasion of Ca9-22 and KJ-1 cells. Inhibited phosphorylation of the FAK-Src kinase-ERK signaling pathway may be involved in the PDT-induced migration/invasion suppression.

Differential gene expression patterns and interaction networks in BCR-ABL-positive and -negative adult acute lymphoblastic leukemias

PURPOSE

To identify gene expression patterns and interaction networks related to BCR-ABL status and clinical outcome in adults with acute lymphoblastic leukemia (ALL).

PATIENTS AND METHODS

DNA microarrays were used to profile a set of 54 adult ALL specimens from the Medical Research Council UKALL XII/Eastern Cooperative Oncology Group E2993 trial (21 p185BCR-ABL-positive, 16 p210BCR-ABL-positive and 17 BCR-ABL-negative specimens).

RESULTS

Using supervised and unsupervised analysis tools, we detected significant transcriptomic changes in BCR-ABL-positive versus -negative specimens, and assessed their validity in an independent cohort of 128 adult ALL specimens. This set of 271 differentially expressed genes (including GAB1, CIITA, XBP1, CD83, SERPINB9, PTP4A3, NOV, LOX, CTNND1, BAALC, and RAB21) is enriched for genes involved in cell death, cellular growth and proliferation, and hematologic system development and function. Network analysis demonstrated complex interaction patterns of these genes, and identified FYN and IL15 as the hubs of the top-scoring network. Within the BCR-ABL-positive subgroups, we identified genes overexpressed (PILRB, STS-1, SPRY1) or underexpressed (TSPAN16, ADAMTSL4) in p185BCR-ABL-positive ALL relative to p210BCR-ABL-positive ALL. Finally, we constructed a gene expression- and interaction-based outcome predictor consisting of 27 genes (including GRB2, GAB1, GLI1, IRS1, RUNX2, and SPP1), which correlated with overall survival in BCR-ABL-positive adult ALL (P = .0001), independent of age (P = .25) and WBC count at presentation (P = .003).

CONCLUSION

We identified prominent molecular features of BCR-ABL-positive adult ALL, which may be useful for developing novel therapeutic targets and prognostic markers in this disease.

Phosphatase type 2A-dependent and -independent pathways for ATR phosphorylation of Chk1

ATM and Rad3-related (ATR) is a regulatory kinase that, when activated by hydroxyurea, UV, or human immunodeficiency virus-1 Vpr, causes cell cycle arrest through Chk1-Ser(345) phosphorylation. We demonstrate here that of these three agents only Vpr requires protein phosphatase type 2A (PP2A) to activate ATR for Chk1-Ser(345) phosphorylation. A requirement for PP2A by Vpr was first shown with the PP2A-specific inhibitor okadaic acid, which reduced Vpr-induced G(2) arrest and Cdk1-Tyr(15) phosphorylation. Using small interference RNA to down-regulate specific subunits of PP2A indicated that the catalytic beta-isoform PP2A(Cbeta) and the A regulatory alpha-isoform PP2A(Aalpha) are involved in the G(2) induction, and these downregulations decreased the Vpr-induced, ATR-dependent phosphorylations of Cdk1-Tyr(15) and Chk1-Ser(345). In contrast, the same down-regulations had no effect on hydroxyurea- or UV-activated ATR-dependent Chk1-Ser(345) phosphorylation. Vpr and hydroxyurea/UV all induce ATR-mediated gammaH2AX-Ser(139) phosphorylation and foci formation, but down-regulation of PP2A(Aalpha) or PP2A(Cbeta) did not decrease gammaH2AX-Ser(139) phosphorylation by any of these agents or foci formation by Vpr. Conversely, H2AX down-regulation had little effect on PP2A(Aalpha/Cbeta)-mediated G(2) arrest and Chk1-Ser(345) phosphorylation by Vpr. The expression of vpr increases the amount and phosphorylation of Claspin, an activator of Chk1 phosphorylation. Down-regulation of either PP2A(Cbeta) or PP2A(Aalpha) had little effect on Claspin phosphorylation, but the amount of Claspin was reduced. Claspin may then be one of the phosphoproteins through which PP2A(Aalpha/Cbeta) affects Chk1 phosphorylation when ATR is activated by human immunodeficiency virus-1 Vpr.

Weak expression of focal adhesion kinase (pp125FAK) in patients with cervical cancer is associated with poor disease outcome

PURPOSE

The pp125 focal adhesion kinase (FAK) plays a pivotal role in tumor cell signaling. FAK expression has been linked to tumor cell invasion and metastasis, but data on cervical cancer are inconclusive. Our goal was to investigate FAK expression in cervical cancer and to assess whether its expression correlates with prognosis.

EXPERIMENTAL DESIGN

FAK expression was examined using immunohistochemistry with sections from 162 resected cervical cancer specimens. Kaplan-Meier survival curves were used to determine the significance of FAK expression in the prognosis of cervical cancer patients.

RESULTS

Specific FAK expression was found in the tumor cells, whereas normal cervical epithelium showed barely any FAK expression. Of 162 invasive cervical cancer specimens, 55 (34%) revealed weak expression of FAK, whereas moderate and strong expression was found in 63 (39%) and 44 (27%) tumors, respectively. Patients with tumors expressing weak amounts of FAK were characterized by a significantly poorer overall survival compared with those with moderate and high intratumoral FAK expression (P = 0.002). Weak expression of FAK correlated with pelvic lymph node metastasis (P = 0.026) and recurrent disease (P = 0.013). Multivariate Cox regression analysis revealed decreased FAK expression and pelvic lymph node metastasis to be significant independent factors predictive of poor disease outcome (hazard ratio, 0.36; P = 0.005; hazard ratio, 2.38; P = 0.018, respectively).

CONCLUSIONS

Weak expression of FAK in invasive cervical cancer is a strong independent predictor of poor patient outcome. Further studies are warranted to elucidate whether FAK expression analysis is a suitable tool identifying patients at high risk even at an early clinical stage.

Focal adhesion kinase: a potential target in cancer therapy

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that plays an important role in signal transduction pathways that are initiated at sites of integrin-mediated cell adhesions and by growth factor receptors. FAK is a key regulator of survival, proliferation, migration and invasion: processes that are all involved in the development and progression of cancer. FAK is also linked to oncogenes at both a biochemical and functional level. Moreover, overexpression and/or increased activity of FAK is common in a wide variety of human cancers, implicating a role for FAK in carcinogenesis. Given the important role of FAK in a large number of processes involved in tumorigenesis, metastasis and survival signalling FAK should be regarded as a potential target in the development of anti-cancer drugs. Therefore, selective inhibitors of FAK need to be developed. Combination of these selective FAK inhibitors with cytotoxic agents could be a very promising anti-cancer therapy.

Up-regulation of focal adhesion kinase in non-small cell lung cancer

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase linked to the integrin and growth factor receptor-signalling pathways that regulates a number of the biological processes involved in neoplastic transformation, invasion and metastases, such as cell adhesion, migration and apoptosis. Its up-regulation might play a role in the tumourigenesis of invasive tumours, but its involvement in human lung cancer tissues has not yet been determined. We immunohistochemically compared FAK expression and localisation in 60 formalin-fixed and paraffin-embedded non-small cell lung cancer (NSCLC) tissues with that in the surrounding non-neoplastic tissue and in a further five microscopically normal lungs. FAK mRNA levels were quantitatively determined by real-time RT-PCR in frozen tissue specimens of all of the tumours and 21 matched non-neoplastic lung parenchymas, and protein expression in 16 homogenates of the matched neoplastic/non-neoplastic specimens was evaluated by Western blotting. The three different techniques showed that FAK is weakly expressed in non-neoplastic lung parenchyma and up-regulated in NSCLCs. Moreover, Western blotting and real-time RT-PCR indicated a statistically significant correlation between FAK up-regulation and higher disease stages (I+II versus III+IV, p=0.019 and 0.028, respectively). Our results provide evidence that FAK is up-regulated in NSCLCs, and suggest its potential involvement in lung cancer progression.

C/EBPalpha inactivation in FAK-overexpressed HL-60 cells impairs cell differentiation

We previously demonstrated that focal adhesion kinase (FAK)-overexpressed (HL-60/FAK) cells have marked resistance against various apoptotic stimuli such as oxidative stress, ionizing radiation and TNF-receptor-induced ligand (TRAIL) compared with vector-transfected (HL-60/Vect) cells. Here, we show that HL-60/FAK cells are highly resistant to all-trans retinoic acid (ATRA)-induced differentiation, whereas original HL-60 or HL-60/Vect cells are sensitive. Treatment with ATRA at 1 muM for 5 days markedly inhibited the proliferation and increased the expression of differentiation markers (CD38, CD11b) in HL-60/Vect cells, but showed no such effect in HL-60/FAK cells. Electrophoretic mobility shift assay (EMSA) using an oligonucleotide for the c/EBP consensus binding sequence showed that c/EBPalpha was activated in ATRA-treated HL-60/Vect cells but not in HL-60/FAK cells, indicating that c/EBPalpha activation by ATRA was impaired in HL-60/FAK cells. In addition, the association of retinoblastoma protein (pRb) and c/EBPalpha after treatment with ATRA was seen in HL-60/Vect cells but not in HL-60/FAK cells. Further, hyperphosphorylation of pRb was observed in HL-60/FAK cells. Finally, the introduction of FAK siRNA into HL-60/FAK cells resulted in the recovery of sensitivity to ATRA-induced differentiation, confirming that the inhibition of HL-60/FAK differentiation resulted from both the induction of pRb hyperphosphorylation and the inhibition of association of pRb and c/EBPalpha.

A crosstalk between the Wnt and the adhesion-dependent signaling pathways governs the chemosensitivity of acute myeloid leukemia

Relapses following chemotherapy are a major hindrance to patients' survival in acute myeloid leukemia (AML). To investigate the role of the hematopoietic niche in the chemoresistance of leukemic cells, we examined two pathways: one mediated by adhesion molecules/integrins, and the other by soluble factors of the morphogen Wnt pathway. In our study, both the adhesion of leukemic blasts to fibronectin and the addition of Wnt antagonists induced, independently, resistance of AML cells to daunorubicin in a cell survival assay. Using pharmacological inhibitors and siRNA, we showed that both resistance pathways required the activity of the glycogen synthase kinase 3beta (GSK3beta). Moreover, the AML cell protection downstream of GSK3beta was mediated by NF-kappaB. A link between the adhesion and the Wnt pathway was found, as adhesion of U937 on human osteoblasts, a component of the hematopoietic niche, triggered the secretion of the Wnt antagonist sFRP-1 and supported resistance to daunorubicin. The osteoblast-conditioned medium could also confer chemoresistance to U937 cells cultured in suspension, and this cell protective effect was abrogated after depletion of sFRP-1. In the context of this potential double in vivo resistance, modulators of the common signal GSK3beta and of its target NF-kappaB could represent important novel therapeutic tools.

Computational methods for comparison of large genomic and proteomic datasets reveal protein markers of metastatic cancer

Large-scale genomic and proteomic analysis has provided a wealth of information on biologically relevant systems, and the ability to analyze this information is crucial to uncovering important biological relationships. However, it has proven difficult to compare large datasets from different sources due to different gene and protein identifiers assigned by individual laboratories and database systems. Here, we describe the design of a fully automated blast program (BlastPro) that facilitates rapid comparison of large protein-protein, nucleotide--nucleotide, or nucleotide--protein datasets from numerous, independent studies. Using this system, we compared several published genomic and proteomic databases for proteins that are upregulated in highly motile, metastatic tumor cells. Analysis of five independent studies comprised of greater than 1 x 10(6) genomic sequences and greater than 1,000 proteins revealed that the cytoskeletal-associated protein alpha-actinin is increased at both the mRNA and protein level in metastatic breast, prostate, and skin cancer cells. Interestingly, spatial analysis of alpha-actinin expression revealed that it is amplified 8-fold in the leading pseudopodium compared to the cell body compartment of migrating cells. These findings indicate that amplification of alpha-actinin and its localization to the leading pseudopodium are potential biomarkers of cancer progression to a more metastatic phenotype. Together, our results demonstrate that the BlastPro system can be used to compare large genomic and proteomic datasets to reveal important biological relationships including those associated with cancer progression.

Intrinsic focal adhesion kinase activity controls orthotopic breast carcinoma metastasis via the regulation of urokinase plasminogen activator expression in a syngeneic tumor model

Expression of focal adhesion kinase (FAK) is elevated in malignant breast cancer, yet the role of intrinsic FAK activity in promoting tumor progression remains undefined. Here, we have inhibited FAK activity or expression in murine 4T1 breast carcinoma cells via dominant-negative focal adhesion kinase-related non-kinase (FRNK) or anti-FAK short hairpin RNA (shRNA) expression, respectively. Neither FRNK nor FAK shRNA ( approximately 80% reduced FAK levels) affected 4T1 proliferation in culture, whereas reduced FAK activity or expression blocked 4T1 cell invasion through Matrigel and resulted in 2-3-fold lower urokinase plasminogen activator (uPA) expression. Control 4T1 cells implanted into mammary fat pads of BALB/c mice exhibited spontaneous metastasis to the lungs, to the peritoneal cavity, and resulted in 90% lethality within 21 days. Whereas FAK shRNA-expressing 4T1 cells formed tumors in mice with low levels of apoptosis, when mammary-injected, these cells did not exhibit lung metastasis after 21 days and caused only 40% lethality up to 60 days. Transient re-expression of wild-type but not kinase-dead FAK in 4T1 FAK shRNA cells promoted uPA production and mammary to lung metastasis within 7 days. In fact, stable human uPA overexpression in 4T1 FAK shRNA cells promoted Matrigel invasion and lung metastasis equal to 4T1 controls. Conversely, treatment with plasminogen activator inhibitor-1 or neutralizing antibody to uPA blocked Matrigel invasion of 4T1 control cells. These studies provide the first direct proof that FAK catalytic activity can facilitate metastatic breast cancer progression by regulating uPA expression.

Having a higher blast percentage in circulation than bone marrow: clinical implications in myelodysplastic syndrome and acute lymphoid and myeloid leukemias

Determining the percentage of peripheral blood (PB) and bone marrow (BM) blasts is important for diagnosing and classifying acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Although most patients with acute leukemia or MDS have a higher percentage of BM blasts than PB blasts, the relative proportion is reversed in some patients. We explored the clinical relevance of this phenomenon in MDS (n = 446), AML (n = 1314), and acute lymphoblastic leukemia (ALL) (n = 385). Among patients with MDS or ALL, but not AML, having a higher blast percentage in PB than in BM was associated with significantly shorter survival. In multivariate analyses, these associations were independent of other relevant predictors, including cytogenetic status. Our findings suggest that MDS and ALL patients who have a higher percentage of PB blasts than BM blasts have more aggressive disease. These data also suggest that MDS classification schemes should take into account the percentage of blasts in PB differently from the percentage of blasts in BM.

The role of focal-adhesion kinase in cancer - a new therapeutic opportunity

Focal-adhesion kinase (FAK) is an important mediator of growth-factor signalling, cell proliferation, cell survival and cell migration. Given that the development of malignancy is often associated with perturbations in these processes, it is not surprising that FAK activity is altered in cancer cells. Mouse models have shown that FAK is involved in tumour formation and progression, and other studies showing that FAK expression is increased in human tumours make FAK a potentially important new therapeutic target.