Egr1 and Gas6 facilitate the adaptation of HEK-293 cells to serum-free media by conferring enhanced viability and higher growth rates

Adaptation of the HEp-2 cell line to totally animal-free culture systems and real-time analysis of cell growth

Routine cell culture demands the use of animal-derived products, mainly fetal bovine serum and swine or bovine trypsin. According to the 3Rs principle and to the European Centre for the Validation of Alternative Methods, animal-free substitutes are strongly recommended for in vitro methods. In this study, the HEp-2 cell line was adapted to different totally animal-free culture systems, such as a serum-free complete medium (VP-SFM), human platelet lysate and a synthetic trypsin (TrypLE™ Express); afterward, cell growth was assessed with the xCELLigence instrument. Animal-free products provided promising results, with performances similar or preferable to the common reagents; therefore their use could be encouraged for both ethical and technical advantages.

Cancer Stem Cells: Emergent Nature of Tumor Emergency

A functional analysis of 167 genes overexpressed in Krebs-2 tumor initiating cells was performed. In the first part of the study, the genes were analyzed for their belonging to one or more of the three groups, which represent the three major phenotypic manifestation of malignancy of cancer cells, namely (1) proliferative self-sufficiency, (2) invasive growth and metastasis, and (3) multiple drug resistance. 96 genes out of 167 were identified as possible contributors to at least one of these fundamental properties. It was also found that substantial part of these genes are also known as genes responsible for formation and/or maintenance of the stemness of normal pluri-/multipotent stem cells. These results suggest that the malignancy is simply the ability to maintain the stem cell specific genes expression profile, and, as a consequence, the stemness itself regardless of the controlling effect of stem niches. In the second part of the study, three stress factors combined into the single concept of "generalized cellular stress," which are assumed to activate the expression of these genes, were defined. In addition, possible mechanisms for such activation were identified. The data obtained suggest the existence of a mechanism for the de novo formation of a pluripotent/stem phenotype in the subpopulation of "committed" tumor cells.

Identification of a novel lncRNA induced by the nephrotoxin ochratoxin A and expressed in human renal tumor tissue

Long non-coding RNAs represent a fraction of the transcriptome that is being increasingly recognized. For most of them no function has been allocated so far. Here, we describe the nature and function of a novel non-protein-coding transcript, named WISP1-AS1, discovered in human renal proximal tubule cells exposed to the carcinogenic nephrotoxin ochratoxin A. WISP1-AS1 overlaps parts of the fourth intron and fifth exon of the Wnt1-inducible signaling pathway protein 1 (WISP1) gene. The transcript is 2922 nucleotides long, transcribed in antisense direction and predominantly localized in the nucleus. WISP1-AS1 is expressed in all 20 samples of a human tissue RNA panel with the highest expression levels detected in uterus, kidney and adrenal gland. Its expression was confirmed in primary tissues of human kidneys. In addition, WISP1-AS1 is expressed at higher levels in renal cell carcinoma (RCC) cell lines compared to primary proximal tubule cells as well as in RCC lesions than in the adjacent healthy control tissue from the same patient. Using specific gapmer antisense oligonucleotides to prevent its upregulation, we show that WISP1-AS1 (1) does not influence the mRNA expression of WISP1, (2) affects transcriptional regulation by Egr-1 and E2F as revealed by RNA-sequencing, enrichment analysis and reporter assays, and (3) modulates the apoptosis-necrosis balance. In summary, WISP1-AS1 is a novel lncRNA with modulatory transcriptional function and the potential to alter the cellular phenotype in situations of stress or oncogenic transformation. However, its precise mode of action and impact on cellular functions require further investigations.

Human Embryonic Kidney 293 Cells: A Vehicle for Biopharmaceutical Manufacturing, Structural Biology, and Electrophysiology

Mammalian cells, e.g., CHO, BHK, HEK293, HT-1080, and NS0 cells, represent important manufacturing platforms in bioengineering. They are widely used for the production of recombinant therapeutic proteins, vaccines, anticancer agents, and other clinically relevant drugs. HEK293 (human embryonic kidney 293) cells and their derived cell lines provide an attractive heterologous system for the development of recombinant proteins or adenovirus productions, not least due to their human-like posttranslational modification of protein molecules to provide the desired biological activity. Secondly, they also exhibit high transfection efficiency yielding high-quality recombinant proteins. They are easy to maintain and express with high fidelity membrane proteins, such as ion channels and transporters, and thus are attractive for structural biology and electrophysiology studies. In this article, we review the literature on HEK293 cells regarding their origins but also stress their advancements into the different cell lines engineered and discuss some significant aspects which make them versatile systems for biopharmaceutical manufacturing, drug screening, structural biology research, and electrophysiology applications.

Strategies to Suspension Serum-Free Adaptation of Mammalian Cell Lines for Recombinant Glycoprotein Production

Serum-free suspension cultures are preferably required for recombinant protein production due to its readiness in upstream/downstream processing and scale-up, therefore increasing process productivity and competitiveness. This type of culture replaces traditional cell culturing as the presence of animal-derived components may introduce lot-a-lot variability and adventitious pathogens to the process. However, adapting cells to serum-free conditions is challenging, time-consuming, and cell line and medium dependent. In this chapter, we present different approaches that can be used to adapt mammalian cell lines from an anchorage-dependent serum supplemented culture to a suspension serum-free culture.

The effects of TGF-alpha, IL-1beta and PDGF on fibroblast adhesion to ECM-derived matrix and KGF gene expression

The goal of this study was to elucidate the control mechanisms by which exogenous proteins regulate keratinocyte growth factor (KGF) expression in fibroblasts adhered to differing substrates and thereby provide insights into both fundamental in vitro cell signaling and cell-biomaterial interaction research. A serum-free culture system in which cells maintained their proliferative capacity was established and employed. The addition of transforming growth factor- alpha (TGF-alpha), interleukin-1beta (IL-1beta) and platelet-derived growth factor-BB (PDGF-BB) individually showed no effect on KGF protein release, however, IL-1beta addition led to increased KGF mRNA transcription, intracellular KGF protein synthesis, and granulocyte-macrophage colony-stimulating factor (GM-CSF) release. Intracellular KGF protein synthesis and extracellular release were enhanced when fibroblasts were treated with a combination of IL-1beta and PDGF-BB which suggests KGF synthesis and release are largely regulated by synergistic mechanisms. Surface-bound fibronectin-derived ligands and individual exogenous proteins promoted fibroblast adhesion to semi-interpenetrating polymer networks (sIPNs) but did not stimulate KGF release despite enhancement of KGF mRNA transcription. Additionally, serum conditioning was found to have a significant impact on KGF synthesis and the subsequent mechanisms controlling KGF release. This study demonstrates that KGF release from fibroblasts is likely regulated by multiple mechanisms involving post-transcriptional and exocytic controls which may be impacted by the presence of serum and how serum is removed from the in vitro cell environment.

Mer receptor tyrosine kinase is a novel therapeutic target in pediatric B-cell acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is currently treated with an intense regimen of chemotherapy yielding cure rates near 80%. However, additional changes using available drugs are unlikely to provide significant improvement in survival. New therapies are warranted given the risk of severe therapy-associated toxicities including infertility, organ damage, and secondary malignancy. Here, we report ectopic expression of the receptor tyrosine kinase Mer in pediatric B-cell ALL. Inhibition of Mer prevented Erk 1/2 activation, increased the sensitivity of B-ALL cells to cytotoxic agents in vitro by promoting apoptosis, and delayed disease onset in a mouse model of leukemia. In addition, we discovered cross-talk between the Mer and mammalian target of rapamycin (mTOR) signaling pathways. Our results identify Mer as a novel therapeutic target in ALL and suggest that inhibitors of Mer will interact synergistically with currently used therapies. This strategy may allow for dose reduction resulting in decreased toxicity and increased survival rates. Mer is aberrantly expressed in numerous other malignancies suggesting that this approach may have broad applications.

Cells by design: a mini-review of targeting cell engineering using DNA microarrays

Recent studies have demonstrated the utility of DNA microarray technology in engineering cellular properties. For instance, cellular adhesion, the necessity of cells to attach to a surface in order to to proliferate, was examined by comparing two distinct HeLa cell lines. Two genes, one encoding a type II membrane glycosylating sialyltransferase (siat7e) and the other encoding a secreted glycoprotein (lama4), were found to influence adhesion. The expression of siat7e correlated with reduced adhesion, whereas expression of lama4 correlated with increased adhesion, as shown by various assays. In a separate example, a gene encoding a mitochondrial assembly protein (cox15) and a gene encoding a kinase (cdkl3), were found to influence cellular growth. Enhanced expression of either gene resulted in slightly higher specific growth rates and higher maximum cell densities for HeLa, HEK-293, and CHO cell lines. Another investigated property was the adaptation of HEK-293 cells to serum-free media. The genes egr1 and gas6, both with anti-apoptotic properties, were identified as potentially improving adaptability by impacting viability at low serum levels. In trying to control apoptosis, researchers found that by altering the expression levels of four genes faim, fadd, alg-2, and requiem, apoptotic response could be altered. In the present work, these and related studies in microorganisms (prokaryote and eukaryote) are examined in greater detail focusing on the approach of using DNA microarrays to direct cellular behavior by targeting select genes.