The role of calcium sulfide in intrinsic and extrinsic apoptotic pathways in non‐small lung cell adenocarcinoma

Abstract

Apoptosis is the process of programed cell death and it is characterized by metabolic changes and energy‐dependent mechanisms. It occurs normally in the development and regeneration of tissues, to insure proper functionality of systems, and it can also function as part of the cellular response against disease or cytotoxicagents. Still, a variety of internal and external stimuli trigger apoptotic cascades, which are categorized in two signaling pathways, extrinsic and intrinsic; they are based on the origin of the stimuli, and the mediators involved. Previous studies in our laboratory, showed that non‐small lung cell adenocarcinoma cell line (ATCC HCC827) treated with proprietary calcium sulfidenanoclusters (CaS) [3.8μM] showed increased apoptotic activity following 48 hours that become statistically significant at 72 hours (p<0.05) without affecting non‐cancerous cell lines (MCR5) after 24‐hours. The objective of this study was to determine the expression of intrinsic (Bcl‐2 and caspase‐3) and extrinsic (caspase‐8 and Bax) apoptotic factors in HCC827 cells upon addition of a single dose of CaS nanoclusters evaluated at 24 hours intervals up to 72‐hours. We hypothesized that CaS nanoclusters will increase the intrinsic and extrinsic apoptotic signaling pathways. DMSO [1%] was used as a negative control and Etoposide[10μM] as a positive control. The flasks were randomly assigned to one of the treatments in triplicates. We used Western Blot, densitometry, and statistical analyses to evaluate changes in expression of the studied proteins. The preliminary data showed that: (1) at 72 hours, the expression of the pro‐apoptotic Bax increased and the anti‐apoptotic Bcl‐2 decreased; (2) at 24 and 48 hours the expression of full caspase‐8 and their respective cleaved variations increased, as well as the pro‐apoptotic caspase‐3 when HCC827 cells were treated with CaS nanoclusters (p<0.05). These results suggest that CaS nanoclusters have apro‐apoptotic effect, involving both intrinsic and extrinsic pathways during the specified timelines. We are currently studying additional pro apoptotic mediators in the intrinsic (caspase‐9, ‐12) and extrinsic (caspase‐7) to elucidate the level of effect of CaS nanoclusters in these pathways.Support or Funding InformationThis work was supported by: UPRPRISE Program NIH Grant #R25GM096955