Apoptotic Effects of Bilirubin on Skin Cancer Cell Lines SK-MEL-3 (Melanoma) and A431 (Non-Melanoma)

BACKGROUND

Bilirubin has long been exclusively considered as a potentially dangerous sign of liver diseases, but it is currently regarded as a reliable signaling molecule as well.

OBJECTIVE

This study investigated the effects of unconjugated bilirubin on survival, proliferation, apoptotic and cell arrest capacities of melanoma SKMEL-3 and non-melanoma A431 skin cancer cells in comparison with normal Human Dermal Fibroblast (HDF) cells.

METHODS

The MTT assay test was used to identify survival and the IC₅₀ at various concentrations of bilirubin on SKMEL-3, A431, and HDF cells for 24h and 48h. The comet assay technique was used to investigate genotoxicity effects, and flow cytometry was run to investigate apoptotic and cell arresting effects of bilirubin on the cells. The gene expression of cyclin D1, cyclin E1, survivin, Bcl-2, and p53 was investigated by qRT-PCR. The molecular docking of bilirubin on CDKs (Cyclin-Dependent Kinases 2, 4, and 6) and pro-apoptotic factors Bad, Bak, Bax, Bid, Bik, and Bim was performed by Autodock software version 2.

RESULTS

The IC₅₀ of bilirubin on HDF, A431, and SKMEL-3 cells was 125, 115, and 95 μM at 24h and 115, 100, and 75 μM at 48h, respectively. Although cell arrest in the G1 phase occurred in all cells, bilirubin induced genotoxicity and apoptosis in SKMEL-3 and A431 cancer cells more pronouncedly than those in normal HDF cells.

CONCLUSION

Bilirubin led to cell arrest in the G₁ phase in SKMEL-3, A431, and HDF cells. Additionally, bilirubin induced apoptotic pathways in SKMEL-3 and A431 cancer cells.

Tailoring the gelatin/chitosan electrospun scaffold for application in skin tissue engineering: an in vitro study

The nanofibrous structure containing protein and polysaccharide has good potential in tissue engineering. The present work aims to study the role of chitosan in gelatin/chitosan nanofibrous scaffolds fabricated through electrospinning process under optimized condition. The performance of chitosan in gelatin/chitosan nanofibrous scaffolds was evaluated by mechanical tests, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and in vitro cell culture on scaffolds with different gelatin/chitosan blend ratios. To assay the influence of chitosan ratio on biocompatibility of the electrospun gelatin/chitosan scaffolds for skin tissue engineering, the culturing of the human dermal fibroblast cells (HDF) on nanofibers in terms of attachment, morphology and proliferation was evaluated. Morphological observation showed that HDF cells were attached and spread well on highly porous gelatin/chitosan nanofibrous scaffolds displaying spindle-like shapes and stretching. The fibrous morphologies of electrospun gelatin/chitosan scaffolds in culture medium were maintained during 7 days. Cell proliferation on electrospun gelatin/chitosan scaffolds was quantified by MTS assay, which revealed the positive effect of chitosan content (around 30%) as well as the nanofibrous structure on the biocompatibility (cell proliferation and attachment) of substrates.