Abstract
Integrins mediate cell adhesion and transmit cellular chemical and mechanical signals bidirectionally. Abnormal activation of integrin signals drives tumor initiation, invasion, metastasis, and therapeutic resistance. Therefore, integrins are ideal tumor theranostic biomarkers. Among the 24 known human integrins, the integrin αvβ3 has been the most intensively studied in tumor theranostics in the past 20 years. Here, we focus on the laminin receptors integrin α6β1 and α6β4, which consist of the α6 integrin subunit and either the β1 or β4 integrin subunit, respectively. Both of these proteins are overexpressed in many cancers, and their expression has been linked to poor prognosis in some cancers. Over the last decade, we and our collaborators have developed several types of integrin α6-targeted probes, including single-photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI) and near-infrared fluorescent imaging (NIRF) probes, for the molecular imaging of tumors. Among them, an integrin α6-targeted SPECT probe has been proven to be safe and efficient for detecting breast cancer in the first-in-human pilot study. Moreover, we have developed integrin α6-targeted therapeutic strategies for the treatment of tumors. In this review, we highlight the latest progress in integrin α6-targeted tumor theranostics.