Primary Human Fetal Lung Fibroblast Cells

Antimony(III) and bismuth(III) compounds have medical applications but their mechanisms are poorly understood. Ucar et al. synthesized four new complexes with imidazolidine-2-thione (IMT) and characterized them using spectroscopic, thermal, and X-ray diffraction methods.

The anticancer activity of compounds 1-4 and the free ligand (IMT) was measured on human breast adenocarcinoma (MCF-7) cell line after 48 h of incubation (Fig. 1). The IC₅₀ values of 1-4 are >30 µM. They exhibited low activity towards MCF-7 cells, with cisplatin being much more active than complexes 1-4. The free ligand was found to be inactive as well. Moreover, the toxicity of 1-4 on normal human fetal lung fibroblast cells (MRC-5) was measured. The IC₅₀ values of complexes 3 and 4 were >30 µM while the IC₅₀ values of 1 and 2 were 5.4 ± 0.2 µM and 15.1 ± 0.9 µM, respectively. The therapeutic potency index (TPI) of antimony compounds (1 and 2) was lower than of bismuth compounds (3 and 4), which indicates the greater toxicity. TPI was calculated as IC₅₀(normal cells)/IC₅₀(tumor cells). Imidazolidine-2-thione complexes (1-4) were less active than dithiocarbamate complexes against cancer cells which can be related to their lower stability (Fig. 1).

Fig. 1. IC₅₀ values for cell viability found for complexes 1-4 and other Sb(III) and Bi(III) dithiocarbamate complexes against MCF-7 (breast) and MRC-5 cells (normal human fetal lung fibroblast cells) (Ucar O, Grześkiewicz A M, et al., 2021).

E2F Inhibitor Upregulates HO-1 mRNA and Protein Levels in Human Lung Fibroblasts

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic and fatal lung disease of unknown etiology. HO-1, an anti-inflammatory enzyme, plays a role in IPF, but the mechanisms that control its expression are unknown. Ye's team investigated the regulation of HO-1 by E2F2 in lung fibroblasts using E2F2 inhibitors, siRNA, and overexpression techniques.

The E2F transcriptional inhibitor HLM006474 (HLM) was used to determine the role of E2Fs in primary human lung fibroblasts (HLF). HLM specifically binds to the E2F family of transcription factors and prevents their DNA binding activity, thus suppressing E2F transcriptional activity. HLF cells were treated with HLM (10 μM) for 24 h and then harvested for RNA extraction and RNA sequencing (RNA-seq). HO-1 mRNA was significantly upregulated in HLF cells treated with HLM (Fig. 2A). Real-time PCR analysis confirmed that HLM treatment resulted in increased HO-1 expression in HLF cells (Fig. 2B). Immunoblotting analysis showed that HLM treatment significantly induced HO-1 protein expression in a time-dependent manner in HLF cells (Fig. 3A) and in a time- and dose-dependent manner in normal human fetal lung fibroblast (IMR90) cells (Fig. 3B, C). Similar results were observed in another lung fibroblast cell line (Mrc5) (Fig. 3D). HLM also increased HO-1 protein expression in human lung small airway epithelial cells (HASEpC). Taken together, these data show that E2F transcription factors repress HO-1 expression.

Fig. 2. E2F inhibitor upregulates HO-1 mRNA level (Ye Q, Taleb SJ, et al., 2022).

Fig. 3. HLM006474 increases HO-1 protein levels (Ye Q, Taleb SJ, et al., 2022).