ABSTRACT
The Grb10 gene on chromosome 7p11.2-p12 belongs to a family of adapter proteins known to interact with a number of receptor tyrosine kinases, such as EGF, ErbB2/Her2, platelet-derived growth factor (PDGF), IGF-I receptors and vascular endothelial growth factor (VEGF) receptor, KDR (kinase insert domain containing receptor). In addition to receptor tyrosine kinases, Grb10 has also been found to interact with non-receptor tyrosine kinases such as Tec and Bcr-Abl, other cellular signaling molecules such as Raf-1, and the mitogen-activated protein (MAP) kinase, MEK. We demonstrated increased expression of Grb10 mRNA in more than one half of primary cervical squamous cell cancers (12 of 15 cases) when compared to corresponding non-cancerous uterine squamous cell tissues. In addition, immunohistochemical staining demonstrated that the Grb10 protein was prominent in the cytoplasm of cancer cells, whereas it was unreactive in the surrounding normal cervical squamous cells. In addition, its interruption by siRNA exhibited marked cell growth inhibition. These data indicate that amplification and increased expression of the Grb10 gene may play a role in the development of a portion of human cervical squamous cell cancer.
Subject(s)
Carcinoma, Squamous Cell/metabolism , Proteins/metabolism , Uterine Cervical Neoplasms/metabolism , Adult , Aged , Carcinoma, Squamous Cell/genetics , Carcinoma, Squamous Cell/pathology , Cell Line, Tumor , Cervix Uteri/metabolism , Cervix Uteri/pathology , Cytoplasm/metabolism , ErbB Receptors/genetics , ErbB Receptors/metabolism , Female , GRB10 Adaptor Protein , Humans , Immunoenzyme Techniques , Middle Aged , Proteins/genetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Up-Regulation , Uterine Cervical Neoplasms/pathologyABSTRACT
The Ras-CRK-Rap1 cellular signal-transduction system is regulated by guanine nucleotide exchange factors (GEFs). Transcription of C3G on chromosome 9q34 and a key member of the GEF gene family is activated by the CRK-adaptor protein; the C3G product is a CRK SH3 domain-binding guanine nucleotide-releasing factor. We document here the amplification of C3G in five of 18 primary non-small cell lung cancers examined and its increased expression in 18 of 28 tumors in comparison to corresponding non-cancerous lung tissues. Immunohistochemical staining revealed prominent C3G protein in the cytoplasm of cancer cells, associated with faint staining at the nucleolar membrane, but C3G was not detectable in normal bronchial mucoepithelial cells or in broncholoalveolar cells of the bronchial/bronchiolar ducts or alveoli. These data indicate that amplification and increased expression of the C3G gene may play some role in human lung carcinogenesis through derangement of the CRK-Rap1 signaling pathway.
Subject(s)
Adaptor Proteins, Signal Transducing , Carcinoma, Non-Small-Cell Lung/metabolism , Guanine Nucleotide-Releasing Factor 2/biosynthesis , Guanine Nucleotide-Releasing Factor 2/genetics , Lung Neoplasms/metabolism , Up-Regulation , Adaptor Proteins, Vesicular Transport/metabolism , Adult , Aged , Aged, 80 and over , Alleles , Carcinoma, Non-Small-Cell Lung/genetics , Cell Line, Tumor , Cell Nucleolus , Chromosomes, Human, Pair 9 , Cytoplasm/metabolism , DNA/chemistry , Female , Gene Dosage , Gene Expression Regulation, Neoplastic , Humans , Immunohistochemistry , Lung Neoplasms/genetics , Male , Microsatellite Repeats , Middle Aged , Proto-Oncogene Proteins c-crk , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction , Transcription, Genetic , rap1 GTP-Binding Proteins/metabolismABSTRACT
Persistent human papillomavirus infections cause infected epithelial cells to lose cellular polarity leading to cell transformation. Glycolipid-enriched membrane (GEM) rafts are implicated in polarized sorting of apical membrane proteins in epithelial cells and even in signal transduction. The MAL and BENE are essential component of the GEM raft's machinery for apical sorting of membrane proteins. In this study we demonstrated down-regulation of MAL and BENE mRNA in over two-thirds of primary cervical squamous cell cancers (14 and 15 of 20 cases, for MAL and BENE, respectively) when compared to corresponding non-cancerous uterine squamous cells. Allelic loss or hyper-methylation was not accompanied by MAL or BENE mRNA down-expression in human primary cervical cancers in microsatellite allelic analysis and HpaII-PCR-based methylation analysis of the MAL and BENE genomic region. In addition, we note down-regulation of these genes in established cervical cancer cell lines. These results suggest that down-regulation of MAL and BENE genes, which are essential components of the cellular polarized sorting system, play an important role in human cervical squamous cell cancer development.
Subject(s)
Carrier Proteins/genetics , Down-Regulation/genetics , Membrane Microdomains/genetics , Membrane Proteins/genetics , Membrane Transport Proteins , Myelin Proteins , Neoplasms, Squamous Cell/genetics , Proteolipids/genetics , Uterine Cervical Neoplasms/genetics , Cell Transformation, Neoplastic/genetics , Female , Glycolipids/genetics , Humans , Myelin and Lymphocyte-Associated Proteolipid ProteinsABSTRACT
The Dvl-1 gene on chromosome 1p36 belongs to a family of highly conserved secreted proteins which regulates embryonic induction, generation of cell polarity and specification of cell fate through activation of Wnt signaling pathways. Wnt signaling activates the gene encoding DVL-1; the latter suppresses beta-catenin by promoting its degradation through enhanced inactivation of glycogen-synthase-kinase 3 (GSK3). Here we demonstrate increased expression of DVL-1 mRNA in over two thirds of primary cervical squamous cell cancers (11 of 15 cases) when compared to corresponding non-cancerous uterine squamous cell tissues. In addition, we noted up-regulation of cyclin D1, a downstream effector of Wnt signal pathway in cervical cancer. Immunohistochemical staining demonstrated that DVL-1 protein was prominent in the cytoplasm of cancer cells whereas it was unreactive in the surrounding normal cervical squamous cells. These data indicate that amplification and increased expression of the DVL-1 gene may play some role in the development of a portion of human cervical squamous cell cancer through derangement of the Wnt signaling pathway.
