DJ-1 knockdown inhibits growth and xenograft‑induced tumor generation of human hepatocellular carcinoma cells

miR-199a/b-3p inhibits HCC cell proliferation and invasion through a novel compensatory signaling pathway DJ-1\Ras\PI3K/AKT

Several studies have reported the effects of DJ-1 gene and miR-199a/b-3p on HCC development. However, whether miR-199a/b-3p regulates HCC progression through a novel compensatory signaling pathway involving DJ-1, Ras, and PI3K/AKT remains unknown. We used (TCGA, HPA, miRWalk and Target scan) databases, cancer and para-tissue HCC patients, dual-luciferase reporter gene analysis, proteomic imprinting, qPCR, cell proliferation, scratch, transport, and flow cytometry to detect the molecular mechanism of DJ-1 and miR-199a/b-3p co-expression in HCC cell lines. Bioinformatics analysis showed that DJ-1 was highly expressed in HCC ((P < 0.001) were closely associated with tumor stage (T), portal vein vascular invasion, OS, DSS, and PFI (P < 0.05); miR-199a/b-3p was lowly expressed in HCC (P < 0.001), which was the upstream regulator of DJ-1. Spearman coefficient r = -0.113, P = 0.031; Dual luciferase gene report verified the negative targeting relationship between them P< 0.001; Western blotting demonstrated that miR-199a/b-3p could inhibit the protein expression of DJ-1, Ras and AKT(P < 0.05); The results of CCK8, cell scratch, Transwell migration and flow cytometry showed that OE + DJ-1 increased the proliferation, migration and invasion ability of HepG2 cells, and decreased the apoptosis process, and the differences were statistically significant (P < 0.05), while miR-199a/b-3p had the opposite effect (P < 0.05).

DJ-1/FGFR-1 Signaling Pathway Contributes to Sorafenib Resistance in Hepatocellular Carcinoma

Sorafenib is the first-line therapeutic regimen targeting against advanced or metastatic stage of hepatocellular carcinoma (HCC). However, HCC patients at these stages will eventually fail sorafenib treatment due to the drug resistance. At present, molecular mechanisms underlying sorafenib resistance are not completely understood. Our past studies have shown that DJ-1 is upregulated in HCC, while DJ-1 knockdown inhibits HCC xenograft-induced tumor growth and regeneration, implying that DJ-1 may be a potential target in for HCC treatment. However, whether DJ-1 plays a regulatory role between tumor cells and vascular endothelial cells and whether DJ-1 contributes to sorafenib resistance in HCC cells are largely unclear. To address these questions, we have performed a series of experiments in the current study, and we found that (1) DJ-1, one of the molecules secreted from HCC cells, promoted angiogenesis and migration of vascular endothelial cells (i.e., ECDHCC-1), by inducing phosphorylation of fibroblast growth factor receptor-1 (FGFR-1), phosphorylation of mTOR, phosphorylation of ERK, and phosphorylation of STAT3; (2) downregulation of FGFR1 inhibited tube formation and migration of ECDHCC-1 cells stimulated by DJ-1; (3) FGFR1 knockdown attenuated the phosphorylation of FGFR1 and impaired the activity of Akt, ERK, and STAT3 signals induced by DJ-1 in ECDHCC-1 cells; (4) knocking down FGFR1 led to the elevated expression of proapoptotic molecules but deceased level of antiapoptotic molecules in sorafenib-resistant HCC cells; and (5) Downregulation of FGFR1 suppressed tumor growth and angiogenesis of sorafenib-resistant HCC cells in vivo. Altogether, our results hinted that DJ-1 plays vital roles in tumor microenvironment in HCC development, and DJ-1/FGFR1 signaling pathway may be a therapeutic target for overcoming sorafenib resistance in treating HCC patients at the late stage.

Moving beyond the Tip of the Iceberg: DJ-1 Implications in Cancer Metabolism

DJ-1, also called Parkinson’s protein 7 (PARK7), is ubiquitously expressed and plays multiple actions in different physiological and, especially, pathophysiological processes, as evidenced by its identification in neurodegenerative diseases and its high expression in different types of cancer. To date, the exact activity of DJ-1 in carcinogenesis has not been fully elucidated, however several recent studies disclosed its involvement in regulating fundamental pathways involved in cancer onset, development, and metastatization. At this purpose, we have dissected the role of DJ-1 in maintaining the transformed phenotype, survival, drug resistance, metastasis formation, and differentiation in cancer cells. Moreover, we have discussed the role of DJ-1 in controlling the redox status in cancer cells, along with the ability to attenuate reactive oxygen species (ROS)-dependent cell death, as well as to mediate ferropotosis. Finally, a mention to the development of therapeutic strategies targeting DJ-1 has been done. We have reported the most recent studies, aiming to shed light on the role played by DJ-1 in different cancer aspects and create the foundation for moving beyond the tip of the iceberg.

Curcumin inhibits proliferation of hepatocellular carcinoma cells through down regulation of DJ-1

PTEN exerts tumor suppressor role through inhibiting PI3K/AKT signaling. DJ-1 plays an oncogenic role through negatively regulation of PTEN expression. Curcumin (Cur) is a phenolic compound extracted from a variety of plant roots, with multiple anti-tumor pharmacological effects. This study aims to investigate whether Cur plays a role in the regulation of DJ-1-PENT/PI3K/AKT signaling as well as the proliferation and apoptosis of hepatocellular carcinoma cells. Normal human hepatocyte HL-7702 and hepatocellular carcinoma cell lines SMMC-7721 and HepG2 were cultured followed by analysis of the expression of DJ-1 and PTEN. SMMC-7721 and HepG2 cells were treated with different concentrations of Cur (0, 5, 10 μM) followed by measuring cell proliferation by CCK-8, caspase-3 activity as well as DJ-1 expression by western blot. In addition, SMMC-7721 or HepG2 cells were divided into two groups: Cur+pcDNA3.1-Blank and Cur+pcDNA3.1-DJ-1 for analysis of the expression of DJ-1, PTEN and p-AKT, cell apoptosis and proliferation. Compared with HL-7702, SMMC-7721 and HepG2 cells displayed significantly higher DJ-1 expression and lower PTEN expression. Cur treatment significantly inhibited proliferation of SMMC-7721 and HepG2 cells, increased caspase-3 activity and downregulated DJ-1 expression. Transfection of pcDNA3.1-DJ-1 significantly increased DJ-1 and p-AKT expression, promoted cell proliferation, but decreased PTEN expression and cell apoptosis. In conclusion, Cur inhibits proliferation of hepatocellular carcinoma cells and PTEN/PI3K/AKT signaling pathway via the reduction of DJ-1 expression, which provides new insights to the anticancer effects of curcumin in hepatocellular carcinoma.

Novel Insights into PARK7 (DJ-1), a Potential Anti-Cancer Therapeutic Target, and Implications for Cancer Progression

The expression of PARK7 is upregulated in various types of cancer, suggesting its potential role as a critical regulator of the pathogenesis of cancer and in the treatment of cancer and neurodegenerative diseases, including Parkinson’s disease, Alzheimer’s disease, and Huntington disease. PARK7 activates various intracellular signaling pathways that have been implicated in the induction of tumor progression, which subsequently enhances tumor initiation, continued proliferation, metastasis, recurrence, and resistance to chemotherapy. Additionally, secreted PARK7 has been identified as a high-risk factor for the pathogenesis and survival of various cancers. This review summarizes the current understanding of the correlation between the expression of PARK7 and tumor progression.

Regulation of Signal Transduction by DJ-1

The ability of DJ-1 to modulate signal transduction has significant effects on how the cell regulates normal processes such as growth, senescence, apoptosis, and autophagy to adapt to changing environmental stimuli and stresses. Perturbations of DJ-1 levels or function can disrupt the equilibrium of homeostatic signaling networks and set off cascades that play a role in the pathogenesis of conditions such as cancer and Parkinson's disease.DJ-1 plays a major role in various pathways. It mediates cell survival and proliferation by activating the extracellular signal-regulated kinase (ERK1/2) pathway and the phosphatidylinositol-3-kinase (PI3K)/Akt pathway. It attenuates cell death signaling by inhibiting apoptosis signal-regulating kinase 1 (ASK1) activation as well as by inhibiting mitogen-activated protein kinase kinase kinase 1 (MEKK1/MAP3K1) activation of downstream apoptotic cascades. It also modulates autophagy through the ERK, Akt, or the JNK/Beclin1 pathways. In addition, DJ-1 regulates the transcription of genes essential for male reproductive function, such as spermatogenesis, by relaying nuclear receptor androgen receptor (AR) signaling. In this chapter, we summarize the ways that DJ-1 regulates these pathways, focusing on how its role in signal transduction contributes to cellular homeostasis and the pathologic states that result from dysregulation.

DJ-1 deficiency attenuates expansion of liver progenitor cells through modulating the inflammatory and fibrogenic niches

Our previous study suggested that DJ-1 has a critical role in initiating an inflammatory response, but its role in the liver progenitor cell (LPC) expansion, a process highly dependent on the inflammatory niche, remains elusive. The objective of this study is to determine the role of DJ-1 in LPC expansion. The correlation of DJ-1 expression with LPC markers was examined in the liver of patients with hepatitis B or hepatitis C virus (HBV and HCV, respectively) infection, primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), nonalcoholic fatty liver disease (NAFLD), cirrhosis or hepatocellular carcinoma (HCC), respectively. The role of DJ-1 in LPC expansion and the formation of LPC-associated fibrosis and inflammation was examined in a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet-induced liver injury murine model. We also determined the ability of hepatic stellate cells (HSCs) in recruiting macrophages in DJ-1 knockout (KO) mice. The expression levels of DJ-1 were upregulated in the liver of HBV, HCV, PBC and PSC patients and DDC-fed mice. Additionally, DJ-1 expression was positively correlated with LPC proliferation in patients with liver injury and mice with DDC exposure. DJ-1 has no direct effect on LPC proliferation. Reduced activation of HSCs and collagen deposition were observed in DJ-1 KO mice. Furthermore, infiltrated CD11b⁺Gr-1^low macrophages and pro-inflammatory factors (IL-6, TNF-α) were attenuated in DJ-1 KO mice. Mechanistically, we found that HSCs isolated from DJ-1 KO mice had decreased secretion of macrophage-mobilizing chemokines, such as CCL2 and CX3CL1, resulting in impaired macrophage infiltration. DJ-1 positively correlates with LPC expansion during liver injury. DJ-1 deficiency negatively regulates LPC proliferation by impairing the formation of LPC-associated fibrosis and inflammatory niches.

A proteomic analysis of mushroom polysaccharide-treated HepG2 cells

The anti-tumor properties of fungal polysaccharides have gained significant recognition in Asia and tropical America. In this study, the differential expression of proteins in normal HepG2 cells and those treated with polysaccharides that had been isolated from Phellinus linteus (PL), Ganoderma lucidum (GL) and Auricularia auricula (AA) was investigated. Using two-dimensional electrophoresis (2DE), a total of 104 protein spots were determined to be overexpressed in these cells compared with noncancerous regions. A total of 59 differentially expressed proteins were identified through MALDI-TOF-MS. In addition, 400 biological processes (BP), 133 cell components (CC) and 146 molecular functions (MF) were enriched by Gene Ontology (GO) analysis, and 78 KEGG pathways were enriched by pathway enrichment. Protein-Protein Interaction (PPI) analysis demonstrated the interaction networks affected by polysaccharides in HepG2 cells. Then, DJ-1 and 14-3-3 were identified as the key proteins in the networks, and the expression of the mRNA and proteins were evaluated using Real-time quantitative PCR (qRT-PCR) and Western blotting (WB), respectively. The results were in agreement with the 2DE. These results provided information on significant proteins of hepatocellular carcinoma (HCC) and form an important basis for the future development of valuable medicinal mushroom resources.