Role of L1CAM in the Regulation of the Canonical Wnt Pathway and Class I MAGE Genes

Expression of CD44 Isoforms in Tumor Samples and Cell Lines of Human Colorectal Cancer

Detection of colorectal cancer biomarkers (CRC) remains an urgent task for the diagnosis and prediction of the disease course. A promising approach is the study of cancer stem cell markers. The cell surface glycoprotein CD44 is very important for CRC and its stem cells. Alternative splicing of 9 variable exons of CD44 mRNA leads to the formation of various isoforms of the protein with different roles in the progression of cancer. Studies of the functions of CD44 isoforms require adequate models considering the distribution of CD44 isoforms in real tumor samples. In the present study, the expression profile of CD44 isoforms in CRC was assessed based on the publicly available mRNA sequencing data of patient tumors from the TCGA-COAD database. It was shown that normal tissues predominantly expressed isoforms 3 and 4 at nearly equal levels, whereas tumors mainly expressed isoforms 2, 3, and 4; isoform 3 was expressed at the highest level. Further, the most relevant cell lines for studying the role of CD44 in CRC were identified based on the analysis of mRNA sequencing data of 55 CRC cell lines form CCLE database.

Chemical Induction of Trophoblast Hypoxia by Cobalt Chloride Leads to Increased Expression of DDIT3

Choriocarcinoma cells BeWo b30 are used to model human placental trophoblast hypoxia using cobalt (II) chloride and hydroxyquinoline derivative (HD) as chemical inducers of hypoxia-inducible factor (HIF). In this study, it was shown that both substances activate the hypoxic pathway and the epithelial–mesenchymal transition and inhibit the pathways of cell proliferation. However, CoCl₂ caused activation of the apoptosis pathway, increased the activity of effector caspases 3 and 7, and increased the expression of the unfolded protein response target DDIT3. The mTORC1 pathway was activated upon exposition to CoCl₂, while HD suppressed this pathway, as it happens during real trophoblast hypoxia. Thus, effect of CoCl₂ on BeWo cells can be a model of severe hypoxia with activation of apoptosis, while HD mimics moderate hypoxia.

Knockdown of the α5 laminin chain affects differentiation of colorectal cancer cells and their sensitivity to chemotherapy

The interaction of tumor cells with the extracellular matrix (ECM) may affect the rate of cancer progression and metastasis. One of the major components of ECM are laminins, the heterotrimeric glycoproteins consisting of α-, β-, and γ-chains (αβγ). Laminins interact with their cell surface receptors and, thus, regulate multiple cellular processes. In this work, we demonstrate that shRNA-mediated knockdown of the α5 laminin chain results in Wnt- and mTORC1-dependent partial dedifferentiation of colorectal cancer cells. Furthermore, we showed that this dedifferentiation involved activation of ER-stress signaling, pathway promoting the sensitivity of cells to 5-fluorouracil.

L1 Cell Adhesion Molecule in Cancer, a Systematic Review on Domain-Specific Functions

L1 cell adhesion molecule (L1CAM) is a glycoprotein involved in cancer development and is associated with metastases and poor prognosis. Cellular processing of L1CAM results in expression of either full-length or cleaved forms of the protein. The different forms of L1CAM may localize at the plasma membrane as a transmembrane protein, or in the intra- or extracellular environment as cleaved or exosomal forms. Here, we systematically analyze available literature that directly relates to L1CAM domains and associated signaling pathways in cancer. Specifically, we chart its domain-specific functions in relation to cancer progression, and outline pre-clinical assays used to assess L1CAM. It is found that full-length L1CAM has both intracellular and extracellular targets, including interactions with integrins, and linkage with ezrin. Cellular processing leading to proteolytic cleavage and/or exosome formation results in extracellular soluble forms of L1CAM that may act through similar mechanisms as compared to full-length L1CAM, such as integrin-dependent signals, but also through distinct mechanisms. We provide an algorithm to guide a step-wise analysis on L1CAM in clinical samples, to promote interpretation of domain-specific expression. This systematic review infers that L1CAM has an important role in cancer progression that can be attributed to domain-specific forms. Most studies focus on the full-length plasma membrane L1CAM, yet knowledge on the domain-specific forms is a prerequisite for selective targeting treatment.

Changes in the Metastatic Properties of MDA-MB-231 Cells after IGFBP6 Gene Knockdown Is Associated with Increased Expression of miRNA Genes Controlling INSR, IGF1R, and CCND1 Genes

Metastatic cascade is associated with the process of epithelial-mesenchymal transition accompanied by changes in cell proliferation, migration, adhesion, and invasiveness mediated by the insulin-like growth factor (IGF) signal pathway. IGFBP6 protein binds IGF and prevents its interaction with receptors. IGFBP6 gene knockdown through RNA-interference inhibits cell migration and increased the rate of proliferation of breast cancer MDA-MB-231 cells. IGFBP6 knockdown cells are characterized by increased expression of MIR100 and MIRLET7A2 genes encoding hsa-miR-100-3p, hsa-miR-100-5p, hsa-let-7a-5p, and hsa-let-7a-2-3p miRNA. The target genes of these microRNAs are IGF2, IGF1R, INSR, and CCND1 associated with IGF signaling pathway and proliferative and migratory activity during the metastatic cascade. A significant decrease in the expression of INSR and CCND1 genes was demonstrated by PCR and microarray analysis.

Metabolic Reprogramming of Trophoblast Cells in Response to Hypoxia

Hypoxia of trophoblast cells is an important regulator of normal development of the placenta. However, some pathological states associated with hypoxia, e.g. preeclampsia, impair the functions of placental cells. Oxyquinoline derivative inhibits HIF-prolyl hydroxylase by stabilizing HIF-1 transcription complex, thus modeling cell response to hypoxia. In human choriocarcinoma cells BeWo b30 (trophoblast model), oxyquinoline increased the expression of a core hypoxia response genes along with up-regulation of NOS3, PDK1, and BNIP3 genes and down-regulation of the PPARGC1B gene. These changes in the expression profile attest to activation of the metabolic cell reprogramming mechanisms aimed at reducing oxygen consumption by enabling the switch from aerobic to anaerobic glucose metabolism and the respective decrease in number of mitochondria. The possibility of practical use of the therapeutic properties of oxyquinoline derivatives is discussed.

Expression of microRNA Genes MIR221, MIR222, and MIR181B1 Increases during Induction of Inflammation in the Endothelial Barrier Model

We studied expression profile of microRNA and their target genes in human umbilical vein endothelial cells (HUVEC) during proinflammatory activation with TNFα. TNFα-induced activation of HUVEC was accompanied by a decrease in the expression of CDKN1B, HIST1H3D, and OIP5 genes that are the common target genes for mature microRNA encoded by MIR221, MIR222, and MIR181B1 genes, whose expression increases in activated cells. Proteins encoded by HIST1H3D and OIP5 genes are associated with chromatin compaction and cell cycle. Our results suggest that fetal endothelial microRNA can appear in the maternal blood during various pathological states, e.g., under conditions of preeclampsia.

TNFα-Induced Expression of Transport Protein Genes in HUVEC Cells Is Associated with Enhanced Expression of Transcription Factor Genes RELB and NFKB2 of the Non-Canonical NF-κB Pathway

Endothelial HUVEC cells used as an in vitro model of the endothelial monolayer in placental barrier were activated by TNFα in a dose of 2 ng/ml for 24 h. Significant changes in the expression of genes of the SLC family transport protein were observed: an increase in the expression of SLC7A2, SLC12A2, SLC9B2, SLC25A37, SLC16A9, and SLC41A2 and a decrease in the expression of SLC40A1. These transporters participate in the transport of iron, magnesium, sodium, potassium, and chloride ions, protons, and amino acids. It was also found that SLC7A2, SLC12A2, SLC9B2, SLC25A37, and SLC41A2 genes have binding sites for transcriptional factor RelB that together with NFKB2 is the main effector of the non-canonical NF-κB pathway. The expression of RELB and NFKB2 genes was also significantly enhanced in TNFα-activated HUVEC cells, which can attest to the important role of the non-canonical NF-κB pathway in the regulation of gene expression of transport proteins in response to TNFα stimulation.

hsa-miR-1973 MicroRNA is Significantly and Differentially Expressed in MDA-MB-231 Cells of Breast Adenocarcinoma and Xenografts Derived from the Tumor

The gene expression profiles of MDA-MB-231 cell line of breast cancer and xenografts derived from this tumor in murine model were analyzed using GeneChip Human Transcriptome array 2.0 platform (Affymetrix). A more than 1000-fold increase in the MIR1973 gene expression was observed in the xenografts compared to the original cell line. Real-time reverse transcription PCR showed that the content of mature hsa-miR-1973 microRNA encoded by this gene was elevated in the xenografts by more than 300 times. According to microarray analysis, none of hsa-miR-1973 target genes available in the databases changed the expression in the cell line and xenografts. A possible role of hsa-miR-1973 is reduction of apoptosis in the tumor.