Myosin Light Chains in the Progression of Cancer

The myosin light chains (MLCs) of non-muscle myosin II are known to regulate cellular architecture and generate cellular forces; they also have an increasingly emerging role in the progression of cancer. The phosphorylation state of the myosin light chains controls the activity of myosins that are implicated in invasion and proliferation. In cancers, when proliferation is greatly increased, cytokinesis relies on phosphorylated light chains to activate the contractile forces used to separate the cells. Likewise, during metastasis, kinase pathways culminate in aligning MLC structures for enhanced cell motility through stress fiber contraction and the accumulation of myosin filaments at the leading edge. This review summarizes the myosin light chain family members known to promote cancer progression and evidence of how their altered activities change the behavior of cells involving the mechanical-based processes of proliferation and cell movements during metastasis. In addition, myosin light chains impact the immune response to cancers and currently serve as biomarkers in staging this disease; a brief summary of these topics is provided at the end of the review.