Correction to: Selenite-mediated production of superoxide radical anions in A549 cancer cells is accompanied by a selective increase in SOD1 concentration, enhanced apoptosis and Se–Cu bonding

Correction to: J Biol Inorg Chem (2014) 19:813–828 https://doi.org/10.1007/s00775-014-1113-x

In the original article there were errors in the methods section. Thus, within Table 1: (i) the primer sequence pair for SOD-2 was incorrectly cited; (ii) the primer sequence pair used for SOD 1 was incorrect and did not target the gene of interest. Additional experiments were performed with correctly designed SOD1 primer pair and the outcomes documented here.

The following table now contains corrected primer sequence pairs.

Corrected Table 1 Sequences of primers used for mRNA detection by RT-PCR

Expression of the target gene products for SOD1 has been validated by independent additional experimentation using new cell samples treated under identical conditions as described in the original paper. Conclusions drawn from the gene analyses were unaltered by these errors and were supported by independent assessment of SOD-1 protein expression and SOD total activity in the original paper—refer to (Fig. 6c; reproduced in the new figure) and original Fig. 7.

The following figures and tables replace outcomes originally reported.

New Fig. 6 and Tables 1and2

Corrected Fig. 6

SOD1 expression is upregulated and SOD activity is increased in selenite-treated cells. A549 cells were incubated with 5 μM selenite, harvested and probed for SOD1 gene expression and total SOD activity. a Representative SOD1 gene expression normalised to the corresponding b-actin in the absence (lanes 1 and 2) and presence (lanes 3 and 4) of selenite for 24 h. Quantitative data representing mean ± SD; n = 3 experiments each run in duplicate. Data represent mean ± SD; n = 4 independent experiments. *Significantly different to the control; P = 0.012

Gene expression and antioxidant activity

Next, the expression of SOD1, its corresponding activity and its cellular distribution in selenite-treated cells were investigated. In response to treatment with 5 μM selenite, the relative SOD1 mRNA levels increased two-fold after 24 h (Fig. 6b). Concomitant with increases in O ^·−₂ levels, total SOD activity increased slightly after 4 h and 6 h and there was eventually a significant twofold increase in activity 24 h after selenite treatment (Fig. 6c). The levels of SOD1 mRNA remained elevated 72 h after addition of 5 μM selenite; however, the fold increase was lower than that measured at the 24-h time point (Table 2). Similarly, exposure of the cells to 2 μM selenite for 24 or 72 h enhanced the levels of SOD1 mRNA, although the absolute fold increase remained similar to that obtained with the higher selenite dose (Table 2).

Corrected Table 2 Select mRNA levels in A549 cells before and after exposure to sodium selenite