In vitro studies of deformation and adhesion properties of transformed cells

The micropipet aspiration technique and the parallel-plate flow chamber were used to investigate the deformation and detachment properties, respectively, of normal and transformed rat fibroblasts. The normal Cloned Rat Embryo Fibroblasts (CREF) cell line was transfected with the T24ras oncogene to produce the transformed cell line CREF T24. The CREF T24 cell line was transfected with a Kirstenras revertant gene (K-rev 1a suppressor) to produce the CT24HKB1 cells, which have the same morphological characteristics as the cells in the CREF line. The cells utilized in this investigation were derived from the parent cell line CREF, the only differences being the presence or absence of the T24ras oncogene and the Kirstenras revertant gene. The detachment and deformation properties, therefore, could be related to the metastatic phenotype of the cell rather than inherent differences between disparate cell lines. Results indicated that transfecting the CREF cell line with theras oncogene greatly modified the detachment and deformation properties. The CREF T24 cells were more easily detached from normal cells and were 50% more deformable. Both CREF and CT24HKB1 showed similar detachment properties. Based on these results, it is speculated that K-rev la reversedras- induced membrane alterations in these cells. Preliminary investigations have demonstrated that both CREF and CREF T24 cells in different phases of the cell cycle differed in morphological characteristics. However, the majority of the cells within a given cell line showed similar deformation characteristics. Current investigations are focusing on characterization of both detachment and deformation properties of these cells as a function of the cell cycle using synchronization techniques.     

Different regulation of vascular endothelial growth factor expression by the ERK and p38 kinase pathways in v-ras, v-raf, and v-myc transformed cells

Here we show that vascular endothelial growth factor (VEGF) mRNA expression is up-regulated in oncogene transformed rat liver epithelial (RLE) cell lines and that the extracellular signal-regulated kinase (ERK) and p38 kinase differentially regulate the oncogene-mediated stimulation of VEGF. The highest level of VEGF mRNA expression was observed in the v-H-ras transformed RLE cell line, followed by the v-raf and v-myc transformed lines. The PD98059 MEK inhibitor was used to block the ERK pathway and SB203580 inhibitor to block the p38 pathway. The parent and the v-H-ras transformed RLE cell lines showed up-regulation of VEGF RNA expression through the ERK pathway and down-regulation of VEGF through the p38 pathway. VEGF was regulated in a comparable manner in a human breast carcinoma cell line. In the v-raf and v-myc transformed RLE lines, positive regulation of VEGF was transduced through the p38 pathway. These findings suggest that (1) oncogenic ras differs from raf and myc in the recruitment of the MAPK signaling pathways for VEGF regulation; (2) that VEGF is regulated in ras transformed and human cancer cell lines in a positive and negative manner by the ERK and p38 signaling pathways.     

Expression of matrix metalloproteinase 8 (MMP-8) and tyrosinase-related protein-1 (TYRP-1) correlates with the absence of metastasis in an isogenic human breast cancer model

The multi-step nature of metastasis poses difficulties in both design and interpretation of experiments to unveil the mechanisms causing the process. In order to facilitate such studies, we have previously derived a pair of breast tumor cell lines that originate from the same breast tumor but which have diametrically opposite metastatic capabilities. In this system, the monoclonal cell line M-4A4 is metastatic to the lungs of athymic mice, whereas clone NM-2C5 is equally tumorigenic but non-metastatic. Here, we report that representational difference analysis (RDA) of cDNA obtained from the two clonal populations revealed an increased expression of tyrosinase-related protein-1 (TYRP-1) and the matrix metalloproteinase-8 (MMP-8) genes in the non-metastatic cell line. RNA and protein analyses in cultured cells and in primary xenograft tissues confirmed that the non-metastatic cell line expresses TYRP-1 and MMP-8 at levels that are at least 20-fold higher than the metastatic counterpart. Other members of the MMP family (MMP-9 and MMP-2) and the tissue inhibitor of metalloproteinase-2 (TIMP-2) were found to be expressed at similar levels in both populations. The effects of MMP-8 and TYRP-1 on in vitro invasion and migration were assessed in cells whose expression of these genes was altered by stable transduction with sense and antisense constructs. Specific down-regulation of MMP-8 in non-metastatic NM-2C5 cells resulted in a 2.5-fold increased capacity to invade through Matrigel. Unlike other members of the matrix metalloproteinase family, MMP-8 has not previously been implicated in the processes of tumorigenesis or metastasis. The successful identification of two proteins that are differentially expressed in these matched clonal cell lines and the tumors that they produce demonstrates the feasibility of using this approach to search for genes that are associated with aberrant differentiation toward metastatic behavior.     

Development of novel cell lines of diabetic dysfunction model fit for cell-based screening tests of medicinal materials

Pdx-1 and Irs-1, genes highly associated with diabetes onset, were knocked down in mouse embryonic stem (ES) cells in order to develop cell line models for diabetes. ES cells with different gene knockdown levels were induced to differentiate to the stage of insulin production. Among the cell lines that differentiated, we identified two in which the levels of expression of both genes were 20–40 % of that of control cells. These cell lines showed appreciable deficiencies in three characteristic malfunctions associated with diabetes, namely, insulin production, insulin reception signaling, and glucose-stimulated insulin secretion. These dysfunctions were consistent with results reported elsewhere from in vivo and in vitro studies. Both cell lines did not show any abnormal morphology such as size, shape, color, and surface roughness. No abnormal expression profiles for 17 genes relevant to diabetes were observed. Therefore, these cell lines fulfilled the criteria for a validated cell model for diabetes. The model cell lines developed here are promising biomaterials for cell-based screening tests of new medicines that may be effective in treating diabetes.     

Cell type-specific reciprocal regulation of HIF1A gene expression is dependent on 5′- and 3′-UTRs

In the present study, we demonstrated the reciprocal regulation of hypoxia-inducible factor 1 alpha (HIF1A) gene expression via untranslated region-(UTR) dependent mechanisms. A 151 nucleotide sequence found in the HIF1A 5′-UTR is sufficient for significant translational up-regulation. On the other hand, the 3′-UTR of HIF1A has been implicated in mRNA degradation. In the non-metastatic breast cancer cell line MCF7, the 3′-UTR-dependent down-regulatory machinery predominates over the 5′-UTR-dependent up-regulation of HIF1A. However, 5′-UTR-dependent up-regulation is dominant among metastatic cell lines (MDA-MB453, U87MG). It is therefore likely that the predominance of 5′-UTR-dependent translational enhancement of HIF1A is critical for the malignant phenotype of cancer cells. PTBP-1, but not HuR, is a candidate RNA binding protein for the translational control of HIF1A.     

Biological processes, properties and molecular wiring diagrams of candidate low-penetrance breast cancer susceptibility genes

Background

The process of malignant transformation, progression and metastasis of melanoma is poorly understood. Gene expression profiling of human cancer has allowed for a unique insight into the genes that are involved in these processes. Thus, we have attempted to utilize this approach through the analysis of a series of primary, non-metastatic cutaneous tumors and metastatic melanoma samples.

Methods

We have utilized gene microarray analysis and a variety of molecular techniques to compare 40 metastatic melanoma (MM) samples, composed of 22 bulky, macroscopic (replaced) lymph node metastases, 16 subcutaneous and 2 distant metastases (adrenal and brain), to 42 primary cutaneous cancers, comprised of 16 melanoma, 11 squamous cell, 15 basal cell skin cancers. A Human Genome U133 Plus 2.0 array from Affymetrix, Inc. was utilized for each sample. A variety of statistical software, including the Affymetrix MAS 5.0 analysis software, was utilized to compare primary cancers to metastatic melanomas. Separate analyses were performed to directly compare only primary melanoma to metastatic melanoma samples. The expression levels of putative oncogenes and tumor suppressor genes were analyzed by semi- and real-time quantitative RT-PCR (qPCR) and Western blot analysis was performed on select genes.

Results

We find that primary basal cell carcinomas, squamous cell carcinomas and thin melanomas express dramatically higher levels of many genes, including SPRR1A/B, KRT16/17, CD24, LOR, GATA3, MUC15, and TMPRSS4, than metastatic melanoma. In contrast, the metastatic melanomas express higher levels of genes such as MAGE, GPR19, BCL2A1, MMP14, SOX5, BUB1, RGS20, and more. The transition from non-metastatic expression levels to metastatic expression levels occurs as melanoma tumors thicken. We further evaluated primary melanomas of varying Breslow's tumor thickness to determine that the transition in expression occurs at different thicknesses for different genes suggesting that the "transition zone" represents a critical time for the emergence of the metastatic phenotype. Several putative tumor oncogenes (SPP-1, MITF, CITED-1, GDF-15, c-Met, HOX loci) and suppressor genes (PITX-1, CST-6, PDGFRL, DSC-3, POU2F3, CLCA2, ST7L), were identified and validated by quantitative PCR as changing expression during this transition period. These are strong candidates for genes involved in the progression or suppression of the metastatic phenotype.

Conclusion

The gene expression profiling of primary, non-metastatic cutaneous tumors and metastatic melanoma has resulted in the identification of several genes that may be centrally involved in the progression and metastatic potential of melanoma. This has very important implications as we continue to develop an improved understanding of the metastatic process, allowing us to identify specific genes for prognostic markers and possibly for targeted therapeutic approaches.     

MicroRNA-100 regulates IGF1-receptor expression in metastatic pancreatic cancer cells

Abstract

Patients with pancreatic adenocarcinoma have the lowest 5 year survival rate and yearly rates of incidence are nearly equal to the mortality rates. Long term cure rates by standard therapies are disappointing owing to disseminated disease at diagnosis and chemotherapeutic resistance. New therapeutic targets are necessary to decrease the progression of pancreatic cancer and the ability to identify targets specific to metastasis would improve patient care. We evaluated the levels of microRNA of metastatic and non-metastatic cell lines. The expression levels of microRNAs and mRNAs were determined using microarray analysis to examine and compare five pancreatic cancer cell lines, two that can metastasize in vivo (S2VP10 and S2CP9) and three that do not metastasize (MiaPaCa2, Panc-1 and ASPC-1). MicroRNA analysis indicated an increase in miR-100 and a decrease in miR-138 expression in metastatic cancer cells. Microarray analysis of different expressions of mRNAs in metastatic and non-metastatic pancreatic cell lines also indicated significantly increased insulin growth factor-1 receptor (IGF1-R) expression in metastatic pancreatic cancer cell lines compared to non-metastatic pancreatic cancer cell lines. To confirm microarray analysis results, western blot and immunocytochemistry were performed. Western blot revealed that IGF1-R expression exhibited in metastatic cancer cell lines a seven-fold increase compared to non-metastatic cell lines. In addition, downstream expressions of the proteins, GRB2 and phosphorylated PI3K, also were increased in aggressive cancer cell lines. Immunocytochemistry confirmed the linkage of IGF1-R to miR-100, because cells transfected with miR-100 inhibitor showed a decrease in IGF1-R. Cells transfected with a miR-138 mimic, however, did not affect IGF1-R expression.     

Genomic Instability of Osteosarcoma Cell Lines in Culture: Impact on the Prediction of Metastasis Relevant Genes

BackgroundOsteosarcoma is a rare but highly malignant cancer of the bone. As a consequence, the number of established cell lines used for experimental in vitro and in vivo osteosarcoma research is limited and the value of these cell lines relies on their stability during culture. Here we investigated the stability in gene expression by microarray analysis and array genomic hybridization of three low metastatic cell lines and derivatives thereof with increased metastatic potential using cells of different passages.ConclusionsConsiderable instability during culture in terms of gene expression and chromosomal aberrations was observed in osteosarcoma cell lines. The use of cells from different passages and a search for genes consistently regulated in early and late passages allows the analysis of metastasis-relevant genes despite the observed instability in gene expression in osteosarcoma cell lines during culture.     

Isolation and characterization of the major form of human MUC18 cDNA gene and correlation of MUC18 over-expression in prostate cancer cell lines and tissues with malignant progression.

Ectopical expression of huMUC18, a cell adhesion molecule in the immunoglobulin gene superfamily, causes a non-metastatic human melanoma cell line to become metastatic in a nude mouse system. To determine if MUC18 expression correlates with the development and malignant progression of prostate cancer, we investigated differential expression of human MUC18 (huMUC18) in normal prostate epithelial cells, prostate cancer cell lines, and prostatic normal and cancer tissues. We cloned and characterized the human MUC18 (huMUC18) cDNA gene from three human prostate cancer cell lines and three human melanoma cell lines. The cDNA sequences from the six human cancer cell lines were identical except differences in one to five nucleotides. The deduced amino acid sequences of the longest ORF were 646 amino acids that were identical in these cDNAs except for one to three amino acid residues. The amino acid sequences of all our huMUC18 cDNA genes are similar to that cloned by other group (GenBank access #M28882) except differences in the same seven amino acids. We conclude that huMUC18 cDNA gene reported here represents the gene product from a major allele. The MUC18 mRNA and protein was expressed in three metastatic prostate cancer cell lines (TSU-PR1, DU145, and PC-3), but not in one non-metastatic prostate cancer cell line (LNCaP.FGC). The expression of huMUC18 in these four cell lines is positively related to their extent of in vitro motility and invasiveness and in vivo metastasis in nude mice. HuMUC18 protein was also expressed at high levels in extracts prepared from tissue sample sections containing high grade prostatic intraepithelial neoplasia (PIN), but weakly expressed in extracts prepared from cultured primary normal prostatic epithelial cells and the normal prostate gland. Immunohistochemical analysis showed that huMUC18 was expressed at higher levels in the epithelial cells of high-grade PIN and prostatic carcinomas, and in cells of a perineural invasion, a lymph node, and a lung metastases compared to that in normal or benign hyperplastic epithelium (BPH). We therefore conclude that MUC18 expression is increased during prostate cancer initiation (high grade PIN) and progression to carcinoma, and in metastatic cell lines and metastatic carcinoma. Increased expression of MUC18 is implicated to play an important role in developing and malignant progression of human prostate cancer. Furthermore, the lacking of predominant cytoplasmic membrane expression of MUC18 appeared to correlate with malignant progression of prostate cancer.     

Metabolic responses of Taxus media transformed cell cultures to the addition of methyl jasmonate

Dedifferentiated Taxus media cell cultures presenting the same genetic characteristics as the parent culture were established from transformed roots. Two transformed cell lines were studied: Rol C, carrying the T‐DNA of A. rhizogenes 9,402 and TXS, carrying both the T‐DNA of A. rhizogenes and the txs transgene of T. baccata under the control of the 35S CaMV promoter. In the second part of a previously optimized two‐stage system, the transformed cell lines were cultured in a production medium supplemented with the elicitor methyl jasmonate. Taxane production in the transformed cultures was compared with an untransformed T. media cell line cultured in the same conditions. The highest taxane production was observed in the TXS cell line when cultured in the optimized production medium with methyl jasmonate, being 265% greater than in the untransformed control and 170% greater than in the Rol C cell line. However, txs expression and the activity of the enzyme taxadiene synthase in the TXS cells were lower than in the line carrying only the rol genes (Rol C). It is also noteworthy that the taxane production as well as the txs gene expression and TXS activity in all the cell lines, both transformed and untransformed, were clearly dependent on the elicitor action. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Recombinant hexahistidine arginine decarboxylase (hisADC) induced endogenous agmatine synthesis during stress

The arginine decarboxylase (ADC) is a significant functional enzyme, synthesizes agmatine through arginine metabolism, and agmatine was reported to posses protective properties in various tissues. This study first optimized the conditions for efficient hexahistidine tagged human ADC (hisADC) gene delivery into mouse fibroblast cell line (NIH3T3) using retroviral vector (pLXSN). Later, the functionality of the delivered hisADC gene in synthesizing agmatine during H₂O₂ injury in NIH3T3 was also elucidated. Amplification of hisADC gene was performed using hisADC specific primers under specified conditions. The hisADC PCR product (1.4 kb) was ligated with pLXSN considering the restriction enzyme sites. The complete hisADC pLXSN clone was transfected into PT67 cell line following CalPhos Mammalian transfection method. RT-PCR and western blot results showed the specific and strong detection of hisADC genes in hisADC PT67 transfected cells compared with normal control and pLXSN transfected PT67 cells. The retrovirus containing hisADC gene (vhisADC) was infected into NIH3T3 (vhisADC NIH) using polybrene reagent. Immunocytochemical results showed hisADC expression in the cytoplasm of vhisADC NIH. HPLC analysis revealed high agmatine concentration in the vhisADC NIH, and the induced agmatine synthesized from the retroviral gene delivery prevented vhisADC NIH from H₂O₂ injury which is evident by the decrease in lactate dehydrogenase (P < 0.05) leakage into the medium and less number of propidium iodide positive cells during injury compared to control group. The obtained results provide compelling evidence that higher level of hisADC transgene expression completely triggered the endogenous agmatine synthesis during H₂O₂ injury thus protecting NIH3T3 cells against cytotoxicity.     

Oncogene alterations in in vitro transformed rat tracheal epithelial cells

10 derivations of rat tracheal epithelial (RTE) cells, including normal cells, normal primary cultures, 7 tumorigenic cell lines and 1 nontumorigenic cell line transformed in vitro by treatment with 7,12-dimethyl-benz[a]anthracene (DMBA), benzo[a]pyrene (BP) and/or 12-O-tetradecanoylphorbol-13-acetate (TPA) were examined for oncogene alterations. No abnormalities of Ha-ras were seen that were suggestive of amplification, rearrangement or the presence of RFLPs. Analysis of specific-point mutations in Ha-ras using Pst I digestion (codon 12, GGA to GCA) or Ha-ras and Ki-ras using Xba I (codon 61, CAA to CTA) were negative. In one cell line derived by DMBA treatment, changes in the c-myc restriction digest pattern were seen after incubation with Bam HI and Hind III. Northern analysis revealed consistent differences between normal and transformed cells when probed with Ha-ras; c-myc expression was of low intensity, and the expression of Ki-ras could not be detected. Transfection of RTE cell DNAs into NIH/3T3 cells did not result in the appearance of morphologic transformants. The studies suggest that Ha-ras or Ki-ras codon 61 A to T transversions (CAA to CTA) are not associated with the immoral/tumorigenic phenotype in RTE cells transformed by DMBA or TPA, and are in contrast to results reported in some other biological systems.     

Alterations in the cyclic AMP signal transduction pathway regulating ribonucleotide reductase gene expression in malignant H-ras transformed cell lines

Ribonucleotide reductase is a highly regulated activity responsible for reducing ribonucleotides to deoxyribonucleotides, which are required for DNA synthesis and DNA repair. We have tested the hypothesis that malignant cell populations contain alterations in signal pathways important in controlling the expression of the two genes that code for ribonucleotide reductase, R1 and R2. A series of radiation and H-ras transformed mouse 10T1/2 cell lines with increasing malignant potential were exposed to stimulators of cAMP synthesis (forskolin and cholera toxin), an inhibitor of cAMP degradation (3-isobutyl-1-methylxanthine) and a biologically stable analogue of cAMP (8-bromo-cAMP). Dramatic elevations in the expression of the R1 and R2 genes at the message and protein levels were observed in malignant metastatic populations, which were not detected in the normal parental cell line or in cells capable of benign tumor formation. These changes in ribonucleotide reductase gene expression occurred without any detectable modifications in the rates of DNA synthesis, showing that they were regulated by a novel mechanism independent of the S phase of the cell cycle. Furthermore, studies with forskolin (a stimulator of the protein kinase A signal pathway) and the tumor promoter 12–0-tetradecanoylphorbol-13-acetate (a stimulator of the protein kinase C signal pathway), alone or in combination, indicated that their effects on R1 and R2 gene expression in a highly malignant cell line were greater than when they were tested individually, suggesting that the two pathways modulating R1 and R2 gene expression can cooperate to regulate ribonucleotide reduction, and interestingly this can occur in a synergistic fashion. Also, a direct relationship between H-ras expression and ribonucleotide reductase gene expression was observed; analysis of forskolin mediated elevations in R1 and R2 message levels closely correlated with the levels of H-ras expression in the various cell lines. In total, these studies demonstrate that ribonucleotide reductase expression is controlled by a complex process, and malignant ras transformed cells contain alterations in the regulation of signal transduction pathways that lead to novel modifications in ribonucleotide reductase gene expression. This signal mechanism, which is aberrantly regulated in malignant cells, may be related to regulatory pathways involved in determining ribonucleotide reductase expression in a S phase independent manner during periods of DNA repair. © 1994 Wiley-Liss, Inc.