SERTAD1 Sensitizes Breast Cancer Cells to Doxorubicin and Promotes Lysosomal Protein Biosynthesis.

Acquired chemoresistance of tumor cells is an unwanted consequence of cancer treatment. Overcoming chemoresistance is particularly important for efficiently improving cancer therapies. Here, using multiple lines of evidence, we report the suppressive role of SERTAD1 in apoptosis/anoikis. Among various breast cancer cell lines, higher SERTAD1 expression was found in MCF7 and MDA-MB-231 in suspension than in adherent cell culture. We revealed an unexpected phenomenon that different types of cell deaths were induced in response to different doses of doxorubicin (Dox) in breast cancer cells, presumably via lysosomal membrane permeabilization. A low dose of Dox highly activated autophagy, while a high dose of the chemotherapy induced apoptosis. Inhibition of SERTAD1 promoted the sensitivity of breast cancer cells to Dox and paclitaxel, leading to a significant reduction in tumor volumes of xenograft mice. Simultaneously targeting cancer cells with Dox and autophagy inhibition successfully induced higher apoptosis/anoikis. The novel role of SERTAD1 in maintaining cellular homeostasis has also been suggested in which lysosomal contents, including LAMP1, LAMP2, CTSB, and CTSD, were reduced in SERTAD1-deficient cells.

Prussian blue/serum albumin/indocyanine green as a multifunctional nanotheranostic agent for bimodal imaging guided laser mediated combinatorial phototherapy.

Developing novel nanotheranostic agent using only clinically approved materials is highly desirable and challenging. In this study, we combined three clinically approved materials, Prussian blue (PB), serum albumin (BSA), and indocyanine green (ICG), by a simple and biocompatible method to prepare a multifunctional theranostic PB-BSA-ICG nanoparticle. The multifunctional nanoparticle system could provide dual mode magnetic resonance (MR) and near infrared (NIR) fluorescence imaging as well as combined photothermal and photodynamic (PTT-PDT) therapy in response to a single NIR laser. This nanoparticle showed an excellent stability in physiological solutions and could suppress the photo-instability of ICG. In the absence of light, the nanoparticles showed no cytotoxicity, but significant cell death was induced through combined PTT-PDT effect after irradiation with NIR laser light. A high tumor accumulation and minimal nonspecific uptake by other major organs of PB-BSA-ICG nanoparticle were observed in vivo, analyzed by T1-weighted MR and NIR fluorescence bimodal imaging in tumor xenograft mice after intravenous injection. The nanoparticles efficiently suppressed the tumor growth through combinatorial phototherapy with no tumor recurrence upon a single NIR laser irradiation. These results demonstrated that PB-BSA-ICG is potentially an interesting nanotheranostic agent for imaging guided cancer therapy by overcoming the limitations of each technology and enhancing the therapeutic efficiency as well as reducing side effects.