Effects of zinc status on cell cycle and viability: An in vitro study in monocytes (THP-1) and muscle (Rhabdomyosarcoma) cells.

Monocyte and muscle cells are considered Zn reservoirs and sensitive to Zn fluctuations, especially in terms of viability. The current study aimed to understand the effect of Zn sufficiency and deficiency on THP-1 monocyte and rhabdomyosarcoma (RD) muscle cell lines. Zinc sufficiency was maintained by supplementing 25 µM of Zn, whereas varying degrees of deficiency were created with intracellular Zn chelator-TPEN in serum-free medium. Cell viability was assessed by MTT assay and the Zn deficiency effect on cell cycle stage was determined through flow cytometry analysis. Zn sufficiency has no-observable effect on cell viability, however, Zn deficiency has a significant positive (P < 0.05) effect on cell death. Cell-cycle analysis has shown a significant higher percentage of THP-1, and RD cells were arrested at Sub-G1 stage in zinc deficiency. Results suggest that cells have the tendency of adaptation to sub-optimal zinc depletion. Further, subnormal level of zinc affected THP-1 and RD cell viability by increasing the cell death at the Sub-G1 stage.