Azoramide prevents MPP+-induced dopaminergic neuronal death via upregulating ER chaperone BiP expression.

Progressive death of dopaminergic (DA) neurons is the main cause of Parkinson's disease (PD). The discovery of drug candidates to prevent DA neuronal death is required to address the pathological aspects and alter the process of PD. Azoramide is a new small molecule compound targeting ER stress, which was originally developed for the treatment of diabetes. In this study, pre-treatment with Azoramide was found to suppress mitochondria-targeting neurotoxin MPP+-induced DA neuronal death and locomotor defects in zebrafish larvae. Further study showed that pre-treatment with Azoramide significantly attenuated MPP+-induced SH-SY5Y cell death by reducing aberrant changes in nuclear morphology, mitochondrial membrane potential, intracellular reactive oxygen species, and apoptotic biomarkers. The mechanistic study revealed that Azoramide was able to up-regulate the expression of ER chaperone BiP and thereby prevented MPP+-induced BiP decrease. Furthermore, pre-treatment with Azoramide failed to suppress MPP+-induced cytotoxicity in the presence of the BiP inhibitor HA15. Taken together, these results suggested that Azoramide is a potential neuroprotectant with pro-survival effects against MPP+-induced cell death through up-regulating BiP expression.

GRP78-targeted and doxorubicin-loaded nanodroplets combined with ultrasound: a potential novel theranostics for castration-resistant prostate cancer.

The construction of multifunctional oncotherapy nanoplatforms that combine diagnosis and treatment remains challenging. Nanodroplets (NDs), which simultaneously enhance ultrasound imaging and therapeutic effects, are a potential strategy for non-invasive drug delivery. To achieve the goals of precise medicine, novel SP94 peptide-modified and doxorubicin-loaded ultrasonic NDs (SP94-DOX-NDs) for castration-resistant prostate cancer (CRPC) targeting and treatment were constructed in this study. The characteristics, contrast-enhanced ultrasound imaging (CEUI), targeting ability to glucose-regulated protein 78 (GRP78)-overexpressing CRPC and anticancer effect of the SP94-DOX-NDs were assessed. The desired SP94-NDs were successfully prepared using the nanoemulsification method using a certain proportion of SP94-PEG-chitosan, perfluoropentane (PFP), Tween 20, and lecithin. SP94-NDs with a size of ∼300 nm showed great biocompatibility and CEUI ability. Compared with blank NDs, SP94-NDs exhibited higher tumor-specific targeting ability due to conjugation between the SP94 peptide and GRP78-overexpressing 22RV1 cells. Most importantly, in vitro and in vivo investigations showed that SP94-DOX-NDs combined with ultrasound could specifically deliver DOX into 22RV1 cells and thereby demonstrated a stronger anticancer effect than DOX-NDs and DOX. Thus, SP94-DOX-NDs may provide an efficient approach for the real-time imaging of tumors and triggered, accurate drug delivery to tumors.

Suppression of ER-stress induction of GRP78 as an anti-neoplastic mechanism of the cardiac glycoside Lanatoside C in pancreatic cancer: Lanatoside C suppresses GRP78 stress induction.

The 78 kilodalton glucose-regulated protein (GRP78) is a major endoplasmic reticulum (ER) molecular chaperone with antiapoptotic properties and a key regulator of the unfolded protein response (UPR). ER-stress induction of GRP78 in cancer cells represents a major pro-survival branch of the UPR. Pancreatic ductal adenocarcinoma (PDAC) remains a highly lethal disease and high level of GRP78 is associated with aggressive disease and poor survival. Recently, we reported that PDAC exhibited high level of ER stress and that GRP78 haploinsufficiency is sufficient to suppress pancreatic tumorigenesis in mice, suggesting the utility of inhibitors of GRP78 expression in combating pancreatic cancer. Screening of clinically relevant compound libraries revealed that cardiac glycosides (CGs) can inhibit ER-stress induction of GRP78 in pancreatic and other types of human cancers. Using the FDA-approved CG compound Lanatoside C (LanC) and human pancreatic cancer cell lines as model systems, we discovered that LanC preferably suppressed ER stress induction of GRP78 and to a lesser extent GRP94. The suppression is at the post-transcriptional level and dependent on the Na+/K+-ATPase ion pump. Overexpression of GRP78 mitigates apoptotic activities of LanC in ER stressed cells. Our study revealed a new function of CGs as inhibitor of stress induction of GRP78, and that this suppression at least in part contributes to the apoptotic activities of CGs in human pancreatic cancer cells in vitro. These findings support further investigation into CGs as potential antineoplastic agents for pancreatic and other cancers which depend on GRP78 for growth and survival.