Cancer Biology Publications and Presentations Copyright (c) 2013 University of Massachusetts Medical School All rights reserved. http://escholarship.umassmed.edu/cancerbiology_pp Recent documents in Cancer Biology Publications and Presentations en-us Fri, 17 May 2013 12:07:18 PDT 3600 Neuropilin-2 promotes branching morphogenesis in the mouse mammary gland http://escholarship.umassmed.edu/cancerbiology_pp/215 http://escholarship.umassmed.edu/cancerbiology_pp/215 Fri, 18 Jan 2013 11:16:57 PST Although the neuropilins were characterized as semaphorin receptors that regulate axon guidance, they also function as vascular endothelial growth factor (VEGF) receptors and contribute to the development of other tissues. Here, we assessed the role of NRP2 in mouse mammary gland development based on our observation that NRP2 is expressed preferentially in the terminal end buds of developing glands. A floxed NRP2 mouse was bred with an MMTV-Cre strain to generate a mammary gland-specific knockout of NRP2. MMTV-Cre;NRP2(loxP/loxP) mice exhibited significant defects in branching morphogenesis and ductal outgrowth compared with either littermate MMTV-Cre;NRP2(+/loxP) or MMTV-Cre mice. Mechanistic insight into this morphological defect was obtained from a mouse mammary cell line in which we observed that VEGF(165), an NRP2 ligand, induces branching morphogenesis in 3D cultures and that branching is dependent upon NRP2 as shown using shRNAs and a function-blocking antibody. Epithelial cells in the mouse mammary gland express VEGF, supporting the hypothesis that this NRP2 ligand contributes to mammary gland morphogenesis. Importantly, we demonstrate that VEGF and NRP2 activate focal adhesion kinase (FAK) and promote FAK-dependent branching morphogenesis in vitro. The significance of this mechanism is substantiated by our finding that FAK activation is diminished significantly in developing MMTV-Cre;NRP2(loxP/loxP) mammary glands compared with control glands. Together, our data reveal a VEGF/NRP2/FAK signaling axis that is important for branching morphogenesis and mammary gland development. In a broader context, our data support an emerging hypothesis that directional outgrowth and branching morphogenesis in a variety of tissues are influenced by signals that were identified initially for their role in axon guidance.

]]> Hira Lal Goel et al. Animals Cells, Cultured Epithelial Cells Female Focal Adhesion Protein-Tyrosine Kinases Gene Expression Regulation, Developmental Immunoblotting Immunohistochemistry Mammary Glands, Animal Mice Mice, Knockout Morphogenesis Neuropilin-2 RNA Interference Reverse Transcriptase Polymerase Chain Reaction Vascular Endothelial Growth Factor A ADAM12 produced by tumor cells rather than stromal cells accelerates breast tumor progression http://escholarship.umassmed.edu/cancerbiology_pp/214 http://escholarship.umassmed.edu/cancerbiology_pp/214 Fri, 18 Jan 2013 11:16:55 PST Expression of ADAM12 is low in most normal tissues but is markedly increased in numerous human cancers, including breast carcinomas. We have previously shown that overexpression of ADAM12 accelerates tumor progression in a mouse model of breast cancer (PyMT). In this study, we found that ADAM12 deficiency reduces breast tumor progression in the PyMT model. However, the catalytic activity of ADAM12 seems to be dispensable for its tumor-promoting effect. Interestingly, we show that ADAM12 endogenously expressed in tumor-associated stroma in the PyMT model does not influence tumor progression, but that ADAM12 expression by tumor cells is necessary for tumor progression in these mice. This finding is consistent with our observation that in human breast carcinoma, ADAM12 is almost exclusively located in tumor cells and, only rarely, seen in the tumor-associated stroma. We hypothesized, however, that the tumor-associated stroma may stimulate ADAM12 expression in tumor cells, on the basis of the fact that TGF-beta1 stimulates ADAM12 expression and is a well-known growth factor released from tumor-associated stroma. TGF-beta1 stimulation of ADAM12-negative Lewis lung tumor cells induced ADAM12 synthesis, and growth of these cells in vivo induced more than 200-fold increase in ADAM12 expression. Our observation that ADAM12 expression is significantly higher in the terminal duct lobular units (TDLU) adjacent to human breast carcinoma compared with TDLUs found in normal breast tissue supports our hypothesis that tumor-associated stroma triggers ADAM12 expression.

]]> Camilla Frohlich et al. ADAM Proteins Animals Breast Neoplasms Cell Growth Processes Cell Line, Tumor Disease Progression Female Humans Immunohistochemistry Male Mammary Neoplasms, Experimental Membrane Proteins Mice Mice, Inbred C57BL Mice, Knockout Stromal Cells IMP3, a new biomarker to predict progression of cervical intraepithelial neoplasia into invasive cancer http://escholarship.umassmed.edu/cancerbiology_pp/213 http://escholarship.umassmed.edu/cancerbiology_pp/213 Fri, 18 Jan 2013 11:16:53 PST The expression of IMP3, an oncofetal protein, has been strongly associated with aggressive cancers. In this study, we investigated whether IMP3 can serve as a biomarker to predict invasive squamous cell carcinoma (SCC) in patients with cervical intraepithelial neoplasia (CIN) II and III. A total of 1249 patients with no dysplasia, CINs, or invasive SCC were studied for IMP3 expression. The 710 patients with CIN II and III in their cervical biopsies were further evaluated for invasive cancer-free survival analysis. The role of IMP3 in the regulation of cell proliferation and migration of HeLa cervical cancer cells was examined by modification of IMP3 expression with small interference RNA. Compared with CIN I or cervical tissues without dysplasia, IMP3 expression was significantly increased not only in invasive SCC but also most importantly in a subset of CIN III cases with concurrent invasive SCC. Importantly, invasive cancer was found only in patients with IMP3-positive CIN II and III, whereas no invasive cancer was detected in patients with IMP3-negative CIN II and III in their follow-up resections (P

]]> Di Lu et al. Adult Carcinoma, Squamous Cell Cell Movement Cell Proliferation Cervical Intraepithelial Neoplasia Disease Progression Disease-Free Survival Female HeLa Cells Humans Kaplan-Meier Estimate Massachusetts Middle Aged Neoplasm Invasiveness Neoplasm Staging Prognosis RNA Interference RNA-Binding Proteins Time Factors Tumor Markers, Biological Uterine Cervical Neoplasms Young Adult Neuropilin-2 regulates alpha6beta1 integrin in the formation of focal adhesions and signaling http://escholarship.umassmed.edu/cancerbiology_pp/212 http://escholarship.umassmed.edu/cancerbiology_pp/212 Fri, 18 Jan 2013 11:16:48 PST The neuropilins (NRPs) contribute to the function of cancer cells in their capacity as VEGF receptors. Given that NRP2 is induced in breast cancer and correlates with aggressive disease, we examined the role of NRP2 in regulating the interaction of breast cancer cells with the ECM. Using epithelial cells from breast tumors, we defined NRP2(high) and NRP2(low) populations that differed in integrin expression and adhesion to laminin. Specifically, the NRP2(high) population adhered more avidly to laminin and expressed high levels of the alpha6beta1 integrin than the NRP2(low) population. The NRP2(high) population formed numerous focal adhesions on laminin that were not seen in the NRP2(low) population. These results were substantiated using breast carcinoma cell lines that express NRP2 and alpha6beta1 integrin. Depletion experiments revealed that adhesive strength on laminin but not collagen is dependent on NRP2, and that VEGF is needed for adhesion on laminin. A specific interaction between NRP2 and alpha6beta1 integrin was detected by co-immunoprecipitation. NRP2 is necessary for focal adhesion formation on laminin and for the association of alpha6beta1 integrin with the cytoskeleton. NRP2 also facilitates alpha6beta1-integrin-mediated activation of FAK and Src. Unexpectedly, we discovered that NRP2 is located in focal adhesions on laminin. The mechanism by which NRP2 regulates the interaction of alpha6beta1 integrin with laminin to form focal adhesions involves PKC activation. Together, our data reveal a new VEGF-NRP2 signaling pathway that activates the alpha6beta1 integrin and enables it to form focal adhesions and signal. This pathway is important in the pathogenesis of breast cancer.

]]> Hira Lal Goel et al. Focal Adhesion Protein-Tyrosine Kinases Neuropilin-2 Integrin alpha6beta1 Gene Expression Regulation, Developmental Role of JNK in mammary gland development and breast cancer http://escholarship.umassmed.edu/cancerbiology_pp/211 http://escholarship.umassmed.edu/cancerbiology_pp/211 Fri, 18 Jan 2013 11:16:45 PST cJun NH(2)-terminal kinase (JNK) signaling has been implicated in the developmental morphogenesis of epithelial organs. In this study, we employed a compound deletion of the murine Jnk1 and Jnk2 genes in the mammary gland to evaluate the requirement for these ubiquitously expressed genes in breast development and tumorigenesis. JNK1/2 was not required for breast epithelial cell proliferation or motility. However, JNK1/2 deficiency caused increased branching morphogenesis and defects in the clearance of lumenal epithelial cells. In the setting of breast cancer development, JNK1/2 deficiency significantly increased tumor formation. Together, these findings established that JNK signaling is required for normal mammary gland development and that it has a suppressive role in mammary tumorigenesis.

]]> Cristina Arrigo Cellurale et al. Animals Cell Growth Processes Cell Movement Female Gene Expression MAP Kinase Signaling System Mammary Glands, Animal Mammary Neoplasms, Experimental Mice Mice, Inbred C57BL Mice, Nude Mice, Transgenic Mitogen-Activated Protein Kinase 8 Mitogen-Activated Protein Kinase 9 Integrin beta4 regulates SPARC protein to promote invasion http://escholarship.umassmed.edu/cancerbiology_pp/210 http://escholarship.umassmed.edu/cancerbiology_pp/210 Fri, 18 Jan 2013 11:16:39 PST The alpha6beta4 integrin (referred to as "beta4" integrin) is a receptor for laminins that promotes carcinoma invasion through its ability to regulate key signaling pathways and cytoskeletal dynamics. An analysis of published Affymetrix GeneChip data to detect downstream effectors involved in beta4-mediated invasion of breast carcinoma cells identified SPARC, or secreted protein acidic and rich in cysteine. This glycoprotein has been shown to play an important role in matrix remodeling and invasion. Our analysis revealed that manipulation of beta4 integrin expression and signaling impacted SPARC expression and that SPARC facilitates beta4-mediated invasion. Expression of beta4 in beta4-deficient cells reduced the expression of a specific microRNA (miR-29a) that targets SPARC and impedes invasion. In cells that express endogenous beta4, miR-29a expression is low and beta4 ligation facilitates the translation of SPARC through a TOR-dependent mechanism. The results obtained in this study demonstrate that beta4 can regulate SPARC expression and that SPARC is an effector of beta4-mediated invasion. They also highlight a potential role for specific miRNAs in executing the functions of integrins.

]]> Kristin D. Gerson et al. Cell Line, Tumor *Gene Expression Regulation, Neoplastic Humans Integrin beta4 MicroRNAs Neoplasm Invasiveness Neoplasm Proteins Neoplasms Osteonectin *Protein Biosynthesis VEGF/Neuropilin-2 Regulation of Bmi-1 and Consequent Repression of IGF-IR Define a Novel Mechanism of Aggressive Prostate Cancer http://escholarship.umassmed.edu/cancerbiology_pp/209 http://escholarship.umassmed.edu/cancerbiology_pp/209 Fri, 18 Jan 2013 11:16:38 PST We show that the VEGF receptor neuropilin-2 (NRP2) is associated with high-grade, PTEN-null prostate cancer and that its expression in tumor cells is induced by PTEN loss as a consequence of c-Jun activation. VEGF/NRP2 signaling represses insulin-like growth factor-1 receptor (IGF-IR) expression and signaling, and the mechanism involves Bmi-1-mediated transcriptional repression of the IGF-IR. This mechanism has significant functional and therapeutic implications that were evaluated. IGF-IR expression positively correlates with PTEN and inversely correlates with NRP2 in prostate tumors. NRP2 is a robust biomarker for predicting response to IGF-IR therapy because prostate carcinomas that express NRP2 exhibit low levels of IGF-IR. Conversely, targeting NRP2 is only modestly effective because NRP2 inhibition induces compensatory IGF-IR signaling. Inhibition of both NRP2 and IGF-IR, however, completely blocks tumor growth in vivo.

]]> Hira Lal Goel et al. Prostatic Neoplasms Neuropilin-2 Receptors, Vascular Endothelial Growth Factor Polycomb Repressive Complex 1 Receptor, IGF Type 1 PTEN Phosphohydrolase Enhancing integrin function by VEGF/neuropilin signaling: Implications for tumor biology http://escholarship.umassmed.edu/cancerbiology_pp/208 http://escholarship.umassmed.edu/cancerbiology_pp/208 Fri, 18 Jan 2013 11:16:36 PST This review advances the hypothesis that the ability of integrins to engage their extracellular matrix ligands and signal can be regulated in tumor cells by vascular endothelial growth factor (VEGF), a major angiogenic factor that also has direct effects on the function of tumor cells. More specifically, we will discuss how neuropilins (NRPs), a distinct class of VEGF receptors, enable the function of specific integrins that contribute to tumor initiation and progression.

]]> Hira Lal Goel et al. Neuropilin-2 Vascular Endothelial Growth Factor A Integrins Decreased expression of Mac-2 (carbohydrate binding protein 35) and loss of its nuclear localization are associated with the neoplastic progression of colon carcinoma http://escholarship.umassmed.edu/cancerbiology_pp/206 http://escholarship.umassmed.edu/cancerbiology_pp/206 Fri, 12 Nov 2010 08:11:36 PST The Mac-2 lectin (carbohydrate binding protein 35) is a soluble, 32- to 35-kDa phosphoprotein that binds galactose-containing glycoconjugates. We report here that the colonic epithelium is a major site of Mac-2 expression in vivo based on immunohistochemistry of human tissue specimens. In this epithelium, proliferating cells at the base of the crypts do not express Mac-2 but its expression increases with differentiation along the crypt-to-surface axis. Mac-2 expression is concentrated in the nuclei of these differentiated epithelial cells. The progression from normal mucosa to adenoma to carcinoma is associated with significant changes in Mac-2 nuclear localization and expression. In all adenomas (9/9) and carcinomas (13/13) examined, Mac-2 was not present in the nucleus but was localized in the cytoplasm. Sequencing of Mac-2 cDNAs from normal mucosa and carcinoma revealed no specific mutations that could account for this loss of nuclear localization. We also observed a 5- to 10-fold decrease in Mac-2 mRNA levels in cancer compared to normal mucosa as well as a significant reduction in the amount of Mac-2 protein expressed. These observations suggest that Mac-2 exclusion from the nucleus and its decreased expression may be related to the neoplastic progression of colon cancer.

]]> Margaret M. Lotz et al. Adenocarcinoma Amino Acid Sequence Antigens, Differentiation Base Sequence Blotting, Northern Cell Nucleus Cell Transformation, Neoplastic Cloning, Molecular Colon Colonic Neoplasms Colonic Polyps DNA DNA, Neoplasm Galectin 3 Humans Immunohistochemistry Intestinal Mucosa Lectins Molecular Sequence Data Molecular Weight Oligodeoxyribonucleotides Polymerase Chain Reaction RNA RNA, Messenger RNA, Neoplasm Laminin receptors: achieving specificity through cooperation http://escholarship.umassmed.edu/cancerbiology_pp/205 http://escholarship.umassmed.edu/cancerbiology_pp/205 Fri, 12 Nov 2010 08:11:33 PST The laminins are a large family of extracellular matrix proteins that can profoundly influence development, differentiation and disease progression. The biological effects of the laminins are mediated by surface receptors that link laminin matrices to intracellular signalling pathways. Several classes of receptors, including integrins and other molecules, may cooperate to provide the specificity apparent in the diverse array of laminin-mediated phenomena. This review assesses our current understanding of laminin receptors and discusses how such receptors could recognize structural differences among the laminins and relay these differences to the cell.

]]> Arthur M. Mercurio Regulation of mitogen-activated protein kinase activation by the cytoplasmic domain of the alpha6 integrin subunit http://escholarship.umassmed.edu/cancerbiology_pp/204 http://escholarship.umassmed.edu/cancerbiology_pp/204 Fri, 12 Nov 2010 08:11:31 PST We examined the possibility that the alpha6A and alpha6B cytoplasmic domain variants of the alpha6beta1 integrin differentially activate p42 and p44 mitogen-activated protein (MAP) kinases. P388D1 macrophages that express equivalent surface levels of either the alpha6Abeta1 or alpha6Bbeta1 integrin were used to examine this issue. Adhesion to laminin-1 mediated by the alpha6Abeta1 integrin triggered activation of a substantial fraction of total p42 and p44 MAP kinases as assessed using a mobility shift assay, immunoblot analysis with a phosphospecific MAP kinase antibody, and an immune complex kinase assay. In contrast, ligation of the alpha6Bbeta1 integrin did not trigger significant MAP kinase activation. These data were confirmed by antibody clustering of the alpha6beta1 integrins. Both the alpha6Abeta1 and alpha6Bbeta1 integrins were capable of activating the p70 ribosomal S6 kinase and this activation, unlike MAP kinase activation, is dependent on phosphoinositide 3-OH kinase. Activation of MAP kinase by alpha6beta1 requires both Ras and protein kinase C activity. A functional correlate for differential activation of MAP kinase was provided by the findings that the alpha6Abeta1 transfectants migrated significantly better on laminin than the alpha6Bbeta1 transfectants and this migration was dependent on MAP kinase activity based on the use of the MAP kinase kinase (MEK1) inhibitor PD98059. Our findings demonstrate that the alpha6beta1 integrin can activate MAP kinase, that this activation is regulated by the cytoplasmic domain of the alpha6 subunit, and that it relates to alpha6beta1-mediated migration.

]]> Jueyang Wei et al. 1-Phosphatidylinositol 3-Kinase Antigens, CD Calcium-Calmodulin-Dependent Protein Kinases Cell Movement Enzyme Activation Flavonoids Integrin alpha6 Laminin Macrophages Mitogen-Activated Protein Kinase 1 Mitogen-Activated Protein Kinase 3 *Mitogen-Activated Protein Kinases Protein Kinase C Ribosomal Protein S6 Kinases ras Proteins Evidence that distinct states of the integrin alpha6beta1 interact with laminin and an ADAM http://escholarship.umassmed.edu/cancerbiology_pp/203 http://escholarship.umassmed.edu/cancerbiology_pp/203 Fri, 12 Nov 2010 08:11:29 PST Integrins can exist in different functional states with low or high binding capacity for particular ligands. We previously provided evidence that the integrin alpha6beta1, on mouse eggs and on alpha6-transfected cells, interacted with the disintegrin domain of the sperm surface protein ADAM 2 (fertilin beta). In the present study we tested the hypothesis that different states of alpha6beta1 interact with fertilin and laminin, an extracellular matrix ligand for alpha6beta1. Using alpha6-transfected cells we found that treatments (e.g., with phorbol myristate acetate or MnCl2) that increased adhesion to laminin inhibited sperm binding. Conversely, treatments that inhibited laminin adhesion increased sperm binding. Next, we compared the ability of fluorescent beads coated with either fertilin beta or with the laminin E8 fragment to bind to eggs. In Ca2+-containing media, fertilin beta beads bound to eggs via an interaction mediated by the disintegrin loop of fertilin beta and by the alpha6 integrin subunit. In Ca2+-containing media, laminin E8 beads did not bind to eggs. Treatment of eggs with phorbol myristate acetate or with the actin disrupting agent, latrunculin A, inhibited fertilin bead binding, but did not induce laminin E8 bead binding. Treatment of eggs with Mn2+ dramatically increased laminin E8 bead binding, and inhibited fertilin bead binding. Our results provide the first evidence that different states of an integrin (alpha6beta1) can interact with an extracellular matrix ligand (laminin) or a membrane-anchored cell surface ligand (ADAM 2).

]]> M. S. Chen et al. ADAM Proteins Amino Acid Sequence Animals Binding Sites Disintegrins Female Integrin alpha6beta1 Integrins Laminin Ligands Male Membrane Glycoproteins Metalloendopeptidases Mice Mice, Inbred ICR Sperm-Ovum Interactions Spermatozoa Transfection Zygote Vascular endothelial growth factor is an autocrine survival factor for neuropilin-expressing breast carcinoma cells http://escholarship.umassmed.edu/cancerbiology_pp/202 http://escholarship.umassmed.edu/cancerbiology_pp/202 Fri, 12 Nov 2010 08:11:26 PST We identify a novel function for the vascular endothelial growth factor (VEGF) in its ability to stimulate an autocrine signaling pathway in metastatic breast carcinoma cells that is essential for their survival. Suppression of VEGF expression in metastatic cells in vitro induced their apoptosis, in addition to inhibiting the constitutively elevated phosphatidylinositol 3'-kinase activity that is characteristic of these cells and important for their survival. Hypoxia enhanced the survival of metastatic cells by increasing VEGF expression. The importance of the VEGF receptor neuropilin was indicated by the ability of a neuropilin-binding VEGF isoform to enhance breast carcinoma survival. Moreover, the expression of neuropilin in neuropilin-deficient breast carcinoma cells protected them from apoptosis. The identification of this VEGF autocrine signaling pathway has important implications for tumor metastasis and therapeutic intervention.

]]> Robin E. Bachelder et al. 1-Phosphatidylinositol 3-Kinase Apoptosis Breast Neoplasms Cell Hypoxia Cell Survival Chromones Endothelial Growth Factors Enzyme Activation Enzyme Inhibitors Humans Lymphokines Morpholines Nerve Tissue Proteins Neuropilin-1 Signal Transduction Vascular Endothelial Growth Factor A Vascular Endothelial Growth Factors PDZ interaction sites in integrin alpha subunits. T14853, TIP/GIPC binds to a type I recognition sequence in alpha 6A/alpha 5 and a novel sequence in alpha 6B http://escholarship.umassmed.edu/cancerbiology_pp/201 http://escholarship.umassmed.edu/cancerbiology_pp/201 Fri, 12 Nov 2010 08:11:23 PST We used published peptide library data to identify PDZ recognition sequences in integrin alpha subunit cytoplasmic domains and found that the alpha(6)A and alpha(5) subunits contain a type I PDZ binding site (TSDA*) (asterisk indicates the stop codon). The alpha(6)A cytoplasmic domain was used for screening a two-hybrid library to find interacting proteins. The bulk of the captured cDNAs (60%) coded for TIP-2/GIPC, a cytoplasmic protein with one PDZ domain. The interaction of TIP-2/GIPC with different integrin subunits was tested in two-hybrid and in vitro binding assays. Surprisingly, TIP-2/GIPC bound strongly to the C terminus of both alpha(6)A and alpha(6)B, although the alpha(6)B sequence (ESYS*) is not suggestive of a PDZ binding site because of its polar C-terminal residue. For high affinity interaction with TIP-2/GIPC, at least one of the residues at positions -1 and -3 must be negatively charged. An aliphatic residue at position 0 increases the affinity of but is not required for this interaction. The alpha(5) integrin subunit also bound to TIP-2/GIPC. The alpha(6) integrin and TIP-2/GIPC co-localize in retraction fibers in carcinoma cells plated on laminin, a finding suggesting a functional interaction in vivo. Our results demonstrate that both splice variants of alpha(6) integrin contain a conserved PDZ binding site that enables interaction with TIP-2/GIPC. The binding site in alpha(6)B defines a new subclass of type I PDZ interaction site, characterized by a non-aliphatic residue at position 0.

]]> Taneli Tani et al. Adaptor Proteins, Signal Transducing Alternative Splicing Amino Acid Sequence Antigens, CD Binding Sites Blotting, Northern Carrier Proteins Cell Adhesion Cells, Cultured Glutathione Transferase Humans Integrin alpha5 Integrin alpha6 Molecular Sequence Data Neuropeptides Peptide Library Plasmids Point Mutation Protein Binding Protein Structure, Tertiary RNA, Messenger Recombinant Proteins Sequence Homology, Amino Acid Tumor Cells, Cultured Two-Hybrid System Techniques Protein kinase A regulates Rac and is required for the growth factor-stimulated migration of carcinoma cells http://escholarship.umassmed.edu/cancerbiology_pp/200 http://escholarship.umassmed.edu/cancerbiology_pp/200 Fri, 12 Nov 2010 08:11:21 PST Members of the Rho family of small GTPases, such as Rho and Rac, are required for actin cytoskeletal reorganization during the migration of carcinoma cells. Phosphodiesterases are necessary for this migration because they alleviate cAMP-dependent protein kinase (PKA)-mediated inhibition of RhoA (O'Connor, K. L., Shaw, L. M., and Mercurio, A. M. (1998) J. Cell Biol. 143, 1749-1760; O'Connor K. L., Nguyen, B.-K., and Mercurio, A. M. (2000), J. Cell Biol. 148, 253-258). In this study, we report that the migration of breast and squamous carcinoma cells toward either lysophosphatidic acid or epidermal growth factor involves not only phosphodiesterase activity but also cooperative signaling from PKA. Furthermore, we demonstrate that Rac1 activation in response to chemoattractant or beta(1) integrin clustering is regulated by PKA and that Rac1 is required for this migration. Also, we find that beta(1) integrin signaling stimulates the rapid and transient activation of PKA. A novel implication of these findings is that carcinoma cell migration is controlled by cAMP-dependent as well as cAMP inhibitory signaling mechanisms.

]]> Kathleen L. O'Connor et al. Antigens, CD29 Breast Neoplasms Chemotaxis Cyclic AMP-Dependent Protein Kinases Epidermal Growth Factor Humans Lysophospholipids Signal Transduction Tumor Cells, Cultured rac GTP-Binding Proteins rhoA GTP-Binding Protein Towards a mechanistic understanding of tumor invasion--lessons from the alpha6beta 4 integrin http://escholarship.umassmed.edu/cancerbiology_pp/198 http://escholarship.umassmed.edu/cancerbiology_pp/198 Fri, 12 Nov 2010 08:11:19 PST This review explores the mechanistic basis of carcinoma migration and invasion by focusing on the contribution of integrins. Integrins are essential for invasion not only for their ability to mediate physical interactions with extracellular matrices, but also for their ability to regulate signaling pathways that control actin dynamics and cell movement, as well as for growth and survival. Our comments center on a unique member of the integrin family, the alpha 6 beta 4 integrin, which is a receptor for the laminin family of basement membrane components. Numerous studies have implicated this integrin in the invasion of solid tumors and have provided a rationale for studying the mechanistic basis of its contribution to the invasive process. Such studies have revealed novel insights into the mechanism of carcinoma invasion that involve both the dynamics of cell migration and signaling pathways that regulate this migration.

]]> Arthur M. Mercurio et al. 1-Phosphatidylinositol 3-Kinase Antigens, Neoplasm Antigens, Surface Cell Movement Cyclic AMP Humans Integrin alpha6beta4 Integrins *Neoplasm Invasiveness Neoplasms Signal Transduction Integrin laminin receptors and breast carcinoma progression http://escholarship.umassmed.edu/cancerbiology_pp/197 http://escholarship.umassmed.edu/cancerbiology_pp/197 Fri, 12 Nov 2010 08:11:16 PST This review explores the mechanistic basis of breast carcinoma progression by focusing on the contribution of integrins. Integrins are essential for progression not only for their ability to mediate physical interactions with extracellular matrices but also for their ability to regulate signaling pathways that control actin dynamics and cell movement, as well as for growth and survival. Our comments center on the alpha6 integrins (alpha6beta1 and alpha6beta4), which are receptors for the laminin family of basement membrane components. Numerous studies have implicated these integrins in breast cancer progression and have provided a rationale for studying the mechanistic basis of their contribution to aggressive disease. Recent work by our group and others on mechanisms of breast carcinoma invasion and survival that are influenced by the alpha6 integrins are discussed.

]]> Arthur M. Mercurio et al. 1-Phosphatidylinositol 3-Kinase Antigens, Neoplasm Antigens, Surface Breast Neoplasms Cell Movement Disease Progression Female Humans Integrin alpha6beta4 Integrins Survival Rate Integrin (alpha 6 beta 4) regulation of eIF-4E activity and VEGF translation: a survival mechanism for carcinoma cells http://escholarship.umassmed.edu/cancerbiology_pp/196 http://escholarship.umassmed.edu/cancerbiology_pp/196 Fri, 12 Nov 2010 08:11:13 PST We define a novel mechanism by which integrins regulate growth factor expression and the survival of carcinoma cells. Specifically, we demonstrate that the alpha 6 beta 4 integrin enhances vascular endothelial growth factor (VEGF) translation in breast carcinoma cells. The mechanism involves the ability of this integrin to stimulate the phosphorylation and inactivation of 4E-binding protein (4E-BP1), a translational repressor that inhibits the function of eukaryotic translation initiation factor 4E (eIF-4E). The regulation of 4E-BP1 phosphorylation by alpha 6 beta 4 derives from the ability of this integrin to activate the PI-3K-Akt pathway and, consequently, the rapamycin-sensitive kinase mTOR that can phosphorylate 4E-BP1. Importantly, we show that this alpha 6 beta 4-dependent regulation of VEGF translation plays an important role in the survival of metastatic breast carcinoma cells by sustaining a VEGF autocrine signaling pathway that involves activation of PI-3K and Akt. These findings reveal that integrin-mediated activation of PI-3K-Akt is amplified by integrin-stimulated VEGF expression and they provide a mechanism that substantiates the reported role of alpha 6 beta 4 in carcinoma progression.

]]> Jun Chung et al. Antigens, Surface Apoptosis Breast Neoplasms Cell Survival Cytoplasm Endothelial Growth Factors Eukaryotic Initiation Factor-4E *Gene Expression Regulation, Neoplastic Humans Integrin alpha6beta4 Integrins Lymphokines Oligonucleotides, Antisense Peptide Initiation Factors Phosphorylation Polyribosomes Protein Structure, Tertiary Protein Transport RNA, Bacterial RNA, Messenger Reverse Transcriptase Polymerase Chain Reaction Signal Transduction Tumor Cells, Cultured Vascular Endothelial Growth Factor A Vascular Endothelial Growth Factors The alpha 6 beta 4 integrin and epithelial cell migration http://escholarship.umassmed.edu/cancerbiology_pp/207 http://escholarship.umassmed.edu/cancerbiology_pp/207 Fri, 12 Nov 2010 08:06:19 PST Although the involvement of alpha 6 beta 4, an integrin laminin receptor, in hemidesmosome organization has dominated the study of this integrin, recent studies are revealing novel functions for alpha 6 beta 4 in the migration of epithelial and carcinoma cells. The engagement of laminin by alpha 6 beta 4 can stabilize actin-rich protrusions and mediate traction forces necessary for cell movement. This integrin also has a significant impact on signaling molecules that stimulate migration and invasion, especially PI3-K and Rho GTPases. Activation of PI3-K by alpha 6 beta 4 enhances the formation of actin protrusions, and it may stimulate the function of other integrins, such as alpha 3 beta 1, that are also important for epithelial migration. Signaling through alpha 6 beta 4 may not always depend on the adhesive functions of this integrin, a possibility that has profound implications for migration and invasion because it implies that the ability of alpha 6 beta 4 to stimulate these processes is not limited to specific matrix environments.

]]> Arthur M. Mercurio et al. Antigens, Surface Cell Movement Epithelial Cells Integrins Dynamic Functions of the α6β4 Integrin in Carcinoma http://escholarship.umassmed.edu/cancerbiology_pp/195 http://escholarship.umassmed.edu/cancerbiology_pp/195 Wed, 10 Nov 2010 12:42:27 PST Citation: Rabinovitz I, Mercurio AM. Dynamic functions of the alpha6beta4 integrin in carcinoma. In, “Cell Motility in Cancer Invasion and Metastasis”, Alan Wells (ed.) Springer. 2006. pp. 159-187. DOI: 10.1007/1-4020-4009-1_8

Summary: The α6β4 integrin plays pivotal but distinct roles in the biology of epithelial and carcinoma cells. In healthy epithelia, its major function is to anchor the epithelium to the basement membrane as a component of either Type I or Type II hemidesmosomes. The signaling capacity of this integrin in the hemidesmosome appears to be minimal. Epithelial wounds or, more importantly, factors linked to malignant transformation and progression can induce dramatic changes in the function of α6β4. In fact, a scenario is emerging of how the function of α6β4 is altered in carcinoma. Factors in the host-tumor microenvironment have the potential to mobilize α6β4 from hemidesmosomes and promote its association with F-actin. This association with F-actin enables this integrin to function in cell migration and to harness traction forces on laminin-containing matrices such as basement membranes, a process that could contribute to the remodeling of basement membranes during tumor invasion. Importantly, this altered localization of α6β4 appears to be coupled to an activation of its signaling potential. The primal signaling event triggered by α6β4 appears to be activation of PI3-K. Although the mechanism by which this occurs needs to be deciphered in more detail, especially with respect to the involvement of growth factor receptors, α6β4-mediated activation of PI3-K and its effectors such as Akt, mTOR and Rac has profound consequences on the biology of carcinoma cells. Arguably, the ability of α6β4 to stimulate the translation of VEGF and possibly other growth factors may be the most significant contribution of this integrin to cancer because of the potential autocrine and paracrine effects of these factors.

Partial preview of chapter available via Google Books.

]]> Isaac Rabinovitz et al. Integrin alpha6beta4 Vascular Endothelial Growth Factors Carcinoma