New gold (III) cyanide complex TGS 121 induces ER stress, proteasome inhibition and death of Ras-hyperactivated cells

Cellular Distribution and Ultrastructural Changes in HaCaT Cells, Induced by Podophyllotoxin and Its Novel Fluorescent Derivative, Supported by the Molecular Docking Studies

Podophyllotoxin (PPT) is an active pharmaceutical ingredient (API) with established antitumor potential. However, due to its systemic toxicity, its use is restricted to topical treatment of anogenital warts. Less toxic PPT derivatives (e.g., etoposide and teniposide) are used intravenously as anticancer agents. PPT has been exploited as a scaffold of new potential therapeutic agents; however, fewer studies have been conducted on the parent molecule than on its derivatives. We have undertaken a study of ultrastructural changes induced by PPT on HaCaT keratinocytes. We have also tracked the intracellular localization of PPT using its fluorescent derivative (PPT-FL). Moreover, we performed molecular docking of both PPT and PPT-FL to compare their affinity to various binding sites of tubulin. Using the Presto blue viability assay, we established working concentrations of PPT in HaCaT cells. Subsequently, we have used selected concentrations to determine PPT effects at the ultrastructural level. Dynamics of PPT distribution by confocal microscopy was performed using PPT-FL. Molecular docking calculations were conducted using Glide. PPT induces a time-dependent cytotoxic effect on HaCaT cells. Within 24 h, we observed the elongation of cytoplasmic processes, formation of cytoplasmic vacuoles, progressive ER stress, and shortening of the mitochondrial long axis. After 48 h, we noticed disintegration of the cell membrane, progressive vacuolization, apoptotic/necrotic vesicles, and a change in the cell nucleus's appearance. PPT-FL was detected within HaCaT cells after ~10 min of incubation and remained within cells in the following measurements. Molecular docking confirmed the formation of a stable complex between tubulin and both PPT and PPT-FL. However, it was formed at different binding sites. PPT is highly toxic to normal human keratinocytes, even at low concentrations. It promptly enters the cells, probably via endocytosis. At lower concentrations, PPT causes disruptions in both ER and mitochondria, while at higher concentrations, it leads to massive vacuolization with subsequent cell death. The novel derivative of PPT, PPT-FL, forms a stable complex with tubulin, and therefore, it is a useful tracker of intracellular PPT binding and trafficking.

New gold(III) complexes TGS 121, 404, and 702 show anti-tumor activity in colitis-induced colorectal cancer: an in vitro and in vivo study

BACKGROUND

Chronic inflammation in the course of inflammatory bowel disease may result in colon cancer, or colitis-associated colorectal cancer (CACRC). It is well established that CACRC is associated with oxidative stress and secretion of multiple pro-inflammatory cytokines, e.g. tumor necrosis factor-α. Recently, we proved that the administration of gold(III) complexes resulted in the alleviation of acute colitis in mice. The aim of the current study was to assess the antitumor effect of a novel series of gold(III) complexes: TGS 121, 404, 512, 701, 702, and 703.

MATERIALS

Analyzed gold(III) complexes were screened in the in vitro studies using colorectal cancer and normal colon epithelium cell lines, SW480, HT-29, and CCD 841 CoN, and in vivo, in the CACRC mouse model.

RESULTS

Of all tested complexes, TGS 121, 404, and 702 exhibited the strongest anti-tumor effect in in vitro viability assay of colon cancer cell lines and in in vivo CACRC model, in which these complexes decreased the total number of colonic tumors and macroscopic score. We also evidenced that the mechanism of action was linked to the enzymatic antioxidant system and inflammatory cytokines.

CONCLUSIONS

TGS 121, 404, and 702 present anti-tumor potential and are an attractive therapeutic option for colorectal cancer.

A New Gold(III) Complex, TGS 703, Shows Potent Anti-Inflammatory Activity in Colitis via the Enzymatic and Non-Enzymatic Antioxidant System-An In Vitro, In Silico, and In Vivo Study

Inflammatory bowel diseases (IBD) and their main representatives, Crohn's disease and ulcerative colitis, are worldwide health-care problems with constantly increasing frequency and still not fully understood pathogenesis. IBD treatment involves drugs such as corticosteroids, derivatives of 5-aminosalicylic acid, thiopurines, and others, with the goal to achieve and maintain remission of the disease. Nowadays, as our knowledge about IBD is continually growing, more specific and effective therapies at the molecular level are wanted. In our study, we tested novel gold complexes and their potential effect on inflammation and IBD in vitro, in silico, and in vivo. A series of new gold(III) complexes (TGS 404, 512, 701, 702, and 703) were designed and screened in the in vitro inflammation studies. In silico modeling was used to study the gold complexes' structure vs. their activity and stability. Dextran sulphate sodium (DSS)-induced mouse model of colitis was employed to characterize the anti-inflammatory activity in vivo. Lipopolysaccharide (LPS)-stimulated RAW264.7 cell experiments proved the anti-inflammatory potential of all tested complexes. Selected on the bases of in vitro and in silico analyses, TGS 703 significantly alleviated inflammation in the DSS-induced mouse model of colitis, which was confirmed by a statistically significant decrease in the macro- and microscopic score of inflammation. The mechanism of action of TGS 703 was linked to the enzymatic and non-enzymatic antioxidant systems. TGS 703 and other gold(III) complexes present anti-inflammatory potential and may be applied therapeutically in the treatment of IBD.