Knockdown of GRP78 enhances cell death by cisplatin and radiotherapy in nasopharyngeal cells

Tumor-associated macrophages confer colorectal cancer 5-fluorouracil resistance by promoting MRP1 membrane translocation via an intercellular CXCL17/CXCL22-CCR4-ATF6-GRP78 axis

Chemotherapy represents a major type of clinical treatment against colorectal cancer (CRC). Aberrant drug efflux mediated by transporters acts as a key approach for tumor cells to acquire chemotherapy resistance. Increasing evidence implies that tumor-associated macrophages (TAMs) play a pivotal role in both tumorigenesis and drug resistance. Nevertheless, the specific mechanism through which TAMs regulate drug efflux remains elusive. Here, we discovered that TAMs endow CRC cells with resistance to 5-fluorouracil (5-FU) treatment via a cell-cell interaction-mediated MRP1-dependent drug efflux process. Mechanistically, TAM-secreted C-C motif chemokine ligand 17 (CCL17) and CCL22, via membrane receptor CCR4, activated the PI3K/AKT pathway in CRC tumor cells. Specifically, phosphorylation of AKT inactivated IP3R and induced calcium aggregation in the ER, resulting in the activation of ATF6 and upregulation of GRP78. Accordingly, excessive GRP78 can interact with MRP1 and promote its translocation to the cell membrane, causing TAM-induced 5-FU efflux. Taken together, our results demonstrated that TAMs promote CRC chemotherapy resistance via elevating the expression of GRP78 to promote the membrane translocation of MRP1 and drug efflux, providing direct proof for TAM-induced drug resistance.

Exosomal ERp44 derived from ER-stressed cells strengthens cisplatin resistance of nasopharyngeal carcinoma

Background

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies in head and neck. Platinum-based chemotherapy is an important treatment for NPC. However, the molecular mechanism of resistance to platinum drug remains unknown. Endoplasmic reticulum resident protein 44(ERp44), an unfolded protein response (UPR)-induced endoplasmic reticulum(ER) protein, is induced during ER stress. This research explored the mechanism of ERp44 in strengthening cisplatin resistance in NPC.

Methods

Western blot and immunohistochemistry were used to investigate the expression of ERp44 and Glucose-Regulated Protein 78(GRP78) in NPC. We took CCK8 to detect the role of ERp44 on cell chemosensitivity. Flow cytometric analysis and western blot were taken to analyze cell apoptosis. We performed differential centrifugation to isolate exosomes from serum or conditioned media of cells and analyzed the impact of exosomal ERp44 on cells cisplatin sensitivity. Finally, the results were confirmed in vivo.

Results

We found the increased expression of ERp44 and GRP78 in NPC and ERp44 was highly expressed in ER-stressed tissues. Cell proliferation was inhibited after cisplatin treatment when ERp44 was knocked down and ERp44 strengthened cisplatin resistance by influencing cell apoptosis and pyroptosis. Then we also collected exosomes and cell viability was increased after the addition of NPC-derived-exosomes with cisplatin treatment. More importantly, our results showed under ERS, NPC cells secreted exosomes containing ERp44 and could transfer them to adjacent cells to strengthen chemoresistance.

Conclusion

Our data suggested that exosomal ERp44 derived from ER-stressed NPC cells took an inevitable role in NPC chemoresistance and might act as a treatment target.

Berberine inhibits proliferation and migration of colorectal cancer cells by downregulation of GRP78

Human colorectal cancer (CRC), a highly malignant and metastatic carcinoma, is resistant to many present anticancer therapies. The inhibition of tumor survival and growth through receptor suppression is a promising way to treat CRC. The study aimed to investigate the effect of a natural plant triterpenoid, berberine (BBR), on SW480 cells and whether its role is mediated by Glucose-regulated protein 78 (GRP78). MTT assay, wound healing assay, and Annexin V-FITC assay were used to measure the effect of BBR on the proliferation, migration, and apoptosis of SW480 cells, respectively. Immunofluorescence and western blotting were used to evaluate both the downregulation of BBR on GRP78 and the role of GRP78 in the effect of BBR on SW480 cells. Our results revealed that BBR inhibited the proliferation and migration, as well as induced the apoptosis of SW480 cells, in a dose-dependent manner. BBR induced the dose-dependent inhibition of cell proliferation in HT-29 cells. BBR inhibited the expression of GRP78 and its localization on the cell surface. Moreover, BBR inhibited the expression of Bax, Bcl-2, c-Myc, and Vimentin and up-regulated the cytokeratin expression in SW480 cells. In addition, we found that the effects of BBR on cell proliferation, migration, and apoptosis in SW480 cells were reversed by the overexpression of GRP78. Our findings demonstrated that BBR inhibited the proliferation and migration and induced the apoptosis of SW480 cells by downregulating the expression of GRP78, and targeting GRP78 might be a potential way to develop the effective anticancer therapy.

Targeted inhibition of GRP78 by HA15 promotes apoptosis of lung cancer cells accompanied by ER stress and autophagy

This study investigated the pathophysiological role of GRP78 in the survival of lung cancer cells. Lung cancer patient data from public databases were used to analyze the expression of GRP78 and its influence on prognoses. In vivo, GRP78 protein expression was analyzed in an established urethane-induced lung tumor mouse model. In vitro, the effects of targeted inhibition of GRP78 by HA15 in lung cancer cells were assessed, with cell viability analyzed using a CCK-8 assay, cell proliferation using an EdU assay, apoptosis and cell cycle using flow cytometry, subcellular structure using electron microscopy, and relative mRNA and protein expression using RT-PCR, western blotting or immunofluorescence assays. The results showed that GRP78 was highly expressed in the lung tissue of lung cancer mice model or patients, and was associated with a poor prognosis. After inhibition of GRP78 in lung cancer cells by HA15, cell viability was decreased in a dose- and time-dependent manner, proliferation was suppressed and apoptosis promoted. Unfolded protein response signaling pathway proteins were activated, and the autophagy-related proteins and mRNAs were upregulated. Therefore, targeted inhibition of GRP78 by HA15 promotes apoptosis of lung cancer cells accompanied by ER stress and autophagy.

Reticulocalbin-1 knockdown increases the sensitivity of cells to Adriamycin in nasopharyngeal carcinoma and promotes endoplasmic reticulum stress-induced cell apoptosis

Nasopharyngeal carcinoma (NPC) mainly appears in southeastern Asian countries, including China. Adriamycin (ADM), a type of antitumor drug, is widely applied in treatments against various cancers. Nevertheless, cancer cells will eventually develop drug resistance to ADM. The present study aims to explore the potential role of reticulocalbin-1 (RCN1) in NPC cells resistance to ADM. Microarray-based analysis was used to screen NPC-related genes, with RCN1 acquired for this current study. RCN1 expression in NPC tissues and cells was determined. The biological function of RCN1 on NPC cell apoptosis was evaluated via gain- and loss-of-function experiments in 5-8 F/ADM and 5-8 F cells by delivering si-RCN1 and RCN1-vector. The function of endoplasmic reticulum (ER) stress on cell apoptosis was measured with the involvement of the PERK-CHOP signaling pathway. Furthermore, tumor formation in nude mice was performed to evaluate the survival condition and RCN1 effects in vivo. RCN1 was highly expressed in NPC tissues and cell lines. The increased expression of ER-related proteins ATF4, CHOP, and the extents of IRE1 and PERK phosphorylation were observed. RCN1 knockdown was found to reduce resistance of NPC cells/tissues to ADM while activating ER stress through the activated PERK-CHOP signaling pathway, which further promoted NPC cell apoptosis. These in vitro findings were detected in vivo on tumor formation in nude mice. In conclusion, the present study provides evidence that RCN1 knockdown stimulates ADM sensitivity in NPC by promoting ER stress-induced cell apoptosis, highlighting a theoretical basis for NPC treatment.

The efficacy of cisplatin on nasopharyngeal carcinoma cells may be increased via the downregulation of fibroblast growth factor receptor 2

Cisplatin is one of the primary compounds used in the treatment of nasopharyngeal carcinoma (NPC), and fibroblast growth factor receptor 2 (FGFR2) has emerged to be a promising target for treatment in various tumors. Therefore, the present study aimed to explore whether the expression levels of FGFR2 in NPC tissues and cell lines were altered, and whether the efficiency of cisplatin was increased following the downregulation of FGFR2. The downregulation of FGFR2 was achieved by transfection with a small interfering RNA against FGFR2. Tissues of patients with NPC were analyzed by immunohistochemistry. Cell viability was examined using a Cell Counting Kit‑8 assay. Cell cycle analysis was performed using flow cytometry. mRNA and protein levels were measured by reverse transcription quantitative polymerase chain reaction and western blot analysis, respectively. FGFR2 was observed to be overexpressed in cancer tissues of patients with NPC and in the NPC SUNE1, C666‑1, 6‑10B and HNE‑3 cell lines, and resulted in an unfavorable prognosis. Cisplatin treatment decreased cell viability and increased FGFR2 expression. The silencing of FGFR2 was demonstrated to augment the effects of cisplatin treatment, including decreasing the cell viability and inducing cell cycle arrest, which involved the increase and decrease of the durations of G1 and S phases, respectively, and a decrease in the expression levels of cyclin D1 and CDC25A, and increasing the rate of apoptosis via the intrinsic apoptosis pathway, as demonstrated by the upregulation of cleaved caspase‑3 and B‑cell lymphoma 2 (Bcl‑2)‑associated X protein and downregulation of Bcl‑2, in SUNE1 and C666‑1 cell lines. FGFR2 was overexpressed in the cancer tissues of patients with NPC and in NPC cell lines, resulting in an unfavorable prognosis. The downregulation of FGFR2 decreased cell viability via cell cycle arrest at G1 phase, and increased the efficacy of the cisplatin‑based induction of apoptosis through the intrinsic apoptosis pathway.