Hep88 mAb-initiated paraptosis-like PCD pathway in hepatocellular carcinoma cell line through the binding of mortalin (HSPA9) and alpha-enolase

V. J, Pal S, Nair BG, Kar R, Mishra N. Paraptosis: a unique cell death mode for targeting cancer

Programmed cell death (PCD) is the universal process that maintains cellular homeostasis and regulates all living systems' development, health and disease. Out of all, apoptosis is one of the major PCDs that was found to play a crucial role in many disease conditions, including cancer. The cancer cells acquire the ability to escape apoptotic cell death, thereby increasing their resistance towards current therapies. This issue has led to the need to search for alternate forms of programmed cell death mechanisms. Paraptosis is an alternative cell death pathway characterized by vacuolation and damage to the endoplasmic reticulum and mitochondria. Many natural compounds and metallic complexes have been reported to induce paraptosis in cancer cell lines. Since the morphological and biochemical features of paraptosis are much different from apoptosis and other alternate PCDs, it is crucial to understand the different modulators governing it. In this review, we have highlighted the factors that trigger paraptosis and the role of specific modulators in mediating this alternative cell death pathway. Recent findings include the role of paraptosis in inducing anti-tumour T-cell immunity and other immunogenic responses against cancer. A significant role played by paraptosis in cancer has also scaled its importance in knowing its mechanism. The study of paraptosis in xenograft mice, zebrafish model, 3D cultures, and novel paraptosis-based prognostic model for low-grade glioma patients have led to the broad aspect and its potential involvement in the field of cancer therapy. The co-occurrence of different modes of cell death with photodynamic therapy and other combinatorial treatments in the tumour microenvironment are also summarized here. Finally, the growth, challenges, and future perspectives of paraptosis research in cancer are discussed in this review. Understanding this unique PCD pathway would help to develop potential therapy and combat chemo-resistance in various cancer.

Silencing of ENO1 by shRNA Inhibits the Proliferation of Gastric Cancer Cells

α-Enolase is a significant subunit of enolase and acts as a glycolytic enzyme responsible for catalyzing the conversion of 2-phosphoglycerate to phosphoenolpyruvate in the anaerobic glycolysis pathway. The research about their role is known little in tumor invasion and metastasis. This research analyzed the effect of α-enolase in proliferation and progression of human gastric cancer. The constructed PLKO.1-ENO1 shRNA vector was transfected into 293 T cells and used to infect gastric cancer cells, MKN45, by using lentivirus method. Negative controls were generated by infection with viruses containing empty vector PLKO.1-scramble-shRNA by the same protocol and using wild-type MKN45 cells as blank control. The silencing effect was confirmed by reverse transcription polymerase chain reaction and Western blotting at messenger RNA and protein levels, respectively. Cell proliferation and chemosensitivity were tested by methyl-thiazolyl-tetrazolium assay. Cell apoptosis was tested by flow cytometry. The cell line α-enolase short hairpin RNA stabling silence α-enolase was successfully constructed. In the α-enolase short hairpin RNA cell lines, messenger RNA and protein expression of α-enolase were significantly lower than those in negative control and blank control groups. The proliferation and clone formation ability were significantly inhibited, cell apoptosis was increased significantly, and the inhibition rate of chemotherapy drugs was increased ( P < .05). Our data provide strong evidence that α-enolase short hairpin RNA interference vector can effectively suppress the proliferation and increase chemosensitivity of MKN45 cells, which may provide a novel gene therapy for gastric cancer.

Hep88 mAb-mediated paraptosis-like apoptosis in HepG2 cells via downstream upregulation and activation of caspase-3, caspase-8 and caspase-9

Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide. Presently, targeted therapy via monoclonal antibodies to specific tumor-associated antigens is being continuously developed. Hep88 mAb has proven to exert tumoricidal effects on the HepG2 cell via a paraptosis-like morphology. To verify the pathway, we then demonstrated downstream up-regulation of caspase-3, caspase-8 and caspase-9, assessingmRNA expression by real-time PCR and associated enzyme activity by colorimetric assay. Active caspase-3 determination was also accomplished by flow cytometry. Active caspase-3 expression was increased by Hep88 mAb treatment in a dose-and time-dependent manner. All of the results indicated that Hep88 mAb induced programmed cell death in the HepG2 cell line from paraptosis-like to apoptosis by downstream induction of caspases. These conclusions imply that Hep88mAb might be a promising tool for the effective treatment of HCC in the future.