Effect of Growth Factors on the Proliferation and Gene Expression of Human Meibomian Gland Epithelial Cells

Abstract

PURPOSE. We hypothesize that growth factors, including epidermal growth factor (EGF) and bovine pituitary extract (BPE), induce proliferation, but not differentiation (e.g., lipid accumulation), of human meibomian gland epithelial cells. We also hypothesize that these actions involve a significant upregulation of genes linked to cell cycle processes, and a significant downregulation of genes associated with differentiation. Our objective was to test these hypotheses.METHODS. Immortalized human meibomian gland and conjunctival epithelial cells were cultured for varying time periods in the presence or absence of EGF, BPE, EGF þ BPE, or serum, followed by cell counting, neutral lipid staining, or RNA isolation for molecular biological procedures.RESULTS. Our studies show that growth factors stimulate a significant, time-dependent proliferation of human meibomian gland epithelial cells. These effects are associated with a significant upregulation of genes linked to cell cycle, DNA replication, ribosomes, and translation, and a significant decrease in those related to cell differentiation, tissue development, lipid metabolic processes, and peroxisome proliferator-activated receptor signaling. Serum-induced differentiation, but not growth factor-related proliferation, elicits a pronounced lipid accumulation in human meibomian gland epithelial cells. This lipogenic response is unique, and is not duplicated by human conjunctival epithelial cells.CONCLUSIONS. Our results demonstrate that EGF and BPE stimulate human meibomian gland epithelial cells to proliferate. Further, our findings show that action is associated with an upregulation of cell cycle and translation ontologies, and a downregulation of genetic pathways linked to differentiation and lipid biosynthesis.

One man's poison is another man's meat: Using azithromycin-induced phospholipidosis to promote ocular surface health

“…Immortalized human meibomian gland epithelial cells (Liu et al 2010) were cultured in the presence or absence of 10% fetal bovine serum, according to published techniques (Liu et al 2013). After reaching 80 to 90% confluence (∼ 5 × 10/ 6 well), cells were exposed to the vehicle (0.02% ethanol) or azithromycin (10 μg/ml; Santa Cruz Biotechnology, TX) for 5 days and then processed for histological and biochemical procedures.…”

Differentiation Patterns of Immortalized Human Meibomian Gland Epithelial Cells in Three-Dimensional Culture

“…The notable differences between 2D format and 3D culture in CK1 expression and cell appearances could raise the important hypothesis that HMGECs may function as ductal epithelial cells rather than acinar cells as long as they are cultured in a 2D format regardless of serum treatment. Liu et al 20 reported that HMGECs exhibited lower cell proliferation and keratinization when cultured with serum-containing medium. 20 In particular, CK6 gene expression was significantly downregulated when…”

“…Liu et al 20 reported that HMGECs exhibited lower cell proliferation and keratinization when cultured with serum-containing medium. 20 In particular, CK6 gene expression was significantly downregulated when…”

“…14 Previous studies, including some from our group, showed the functional influence of cultivation conditions, 15,16 neurotransmitters, 17,18 growth factors, 19,20 x-3 fatty acids, 21 sex hormones, 22,23 and pharmacologic substances 24 on HMGEC. However, all of these studies rely on 2D cell culture conditions or limited animal experiments.…”

The Combined Effect of Azithromycin and Insulin-Like Growth Factor-1 on Cultured Human Meibomian Gland Epithelial Cells

“…19 Cells were treated with ethanol vehicle, 10 lg/mL AZM (Santa Cruz Biotechnology, Dallas, TX, USA), 10 nM IGF-1 (National Hormone and Peptide Program, Torrance, CA, USA), or a combination of 10 lg/mL AZM and 10 nM IGF-1 for 5 to 13 days.…”