Nickel may contribute to EGFR mutation and synergistically promotes tumor invasion in EGFR-mutated lung cancer via nickel-induced microRNA-21 expression

•Nickel accumulation in lung tissues is associated with EGFR mutations, miR-21 expression, and a poor outcome in lung cancer never-smoking patients.•Nickel-mediated miR-21 expression, at least in part, synergistically promotes invasiveness via decreased the expression of RECK and SPRY2 in EGFR-mutated lung cancer cells.