Downregulation of metabotropic glutamate receptor 5 inhibits hepatoma development in a neurotoxin rotenone-induced Parkinson's disease model

Expression of mGluR5 in Pediatric Hodgkin and Non-Hodgkin lymphoma-A Comparative Analysis of Immunohistochemical and Clinical Findings Regarding the Association between Tumor and Paraneoplastic Neurological Disease

Autoantibodies targeting the neuronal antigen metabotropic glutamate receptor 5 (mGluR5) have been identified in patients with Ophelia syndrome, which describes a co-occurrence of paraneoplastic limbic encephalitis and Hodgkin lymphoma (HL). Little data exist regarding frequency and function of mGluR5 in HL and its potential role in causing seropositive paraneoplastic disease. We studied a representative cohort of pediatric HL and NHL patients (n = 57) using immunohistochemistry and fluorescence staining to investigate mGluR5 expression. All lymphoma tissues displayed positive mGluR5 staining, with focus on Hodgkin-Reed-Sternberg (H-RS) cells. We did not detect any mGluR5 staining in tumor-free lymph nodes, which is consistent with the absence of GRM5 transcripts in RNA-sequencing data from non-malignant B and T cells. The frequent presence in pediatric lymphoma falls in line with reports of mGluR5 expression and associated tumor progression in other malignancies. We tested for correlation with clinical features, focusing on disease progression and neurological symptoms. Low mGluR5 expression in H-RS cells correlated with young patient age (<15 years) and positive histology for EBV infection. Paraneoplastic or neurological symptoms were found exclusively in HL patients. While an impact of mGluR5 on HL severity remains possible, a prognostic value of mGluR5 expression levels requires further investigation.

The Parkinson's disease-associated protein α-synuclein inhibits hepatoma by exosome delivery

Numerous epidemiological studies suggest a link between Parkinson's disease (PD) and cancer. However, their relevant pathogenesis is not clear. In the present study, we investigated the potential role of exosome-delivered α-synuclein (α-syn) in the regulation between PD and liver cancer. We cultured hepatocellular carcinoma (HCC) cells with exosomes derived from conditioned medium of the PD cellular model, and injected exosomes enriched with α-syn into the striatum of a liver cancer rat model. We found that α-syn-contained exosomes from the rotenone-induced cellular model of PD suppressed the growth, migration, and invasion of HCC cells. Integrin αVβ5 in exosomes from the rotenone-induced PD model was higher than that in the control, resulting in more α-syn-contained exosomes being taken up by HCC cells. Consistently, in vivo experiments with rat models also confirmed exosome-delivered α-syn inhibited liver cancer. These findings illustrate the important role of PD-associated protein α-syn inhibiting hepatoma by exosome delivery, suggesting a new mechanism underlying the link between these two diseases and therapeutics of liver cancer.

Upregulation of Parkinson's disease-associated protein alpha-synuclein suppresses tumorigenesis via interaction with mGluR5 and gamma-synuclein in liver cancer

Numerous epidemiological studies suggest a link between Parkinson's disease (PD) and cancer, indicating that PD-associated proteins may mediate the development of cancer. Here, we investigated a potential role of PD-associated protein α-synuclein in regulating liver cancer progression in vivo and in vitro. We found the negative correlation of α-synuclein with metabotropic glutamate receptor 5 (mGluR5) and γ-synuclein by analyzing the data from The Cancer Genome Atlas database, liver cancer patients and hepatoma cells with overexpressed α-synuclein. Moreover, upregulated α-synuclein suppressed the growth, migration, and invasion. α-synuclein was found to associate with mGluR5 and γ-synuclein, and the truncated N-terminal of α-synuclein was essential for the interaction. Furthermore, overexpressed α-synuclein exerted the inhibitory effect on hepatoma cells through the degradation of mGluR5 and γ-synuclein via α-synuclein-dependent autophagy-lysosomal pathway (ALP). Consistently, in vivo experiments with rotenone-induced rat model of PD also confirmed that, upregulated α-synuclein in liver cancer tissues through targeting on mGluR5/α-synuclein/γ-synuclein complex inhibited tumorigenesis involving in ALP-dependent degradation of mGluR5 and γ-synuclein. These findings give an insight into an important role of PD-associated protein α-synuclein accompanied by the complex of mGluR5/α-synuclein/γ-synuclein in distant communications between PD and liver cancer, and provide a new strategy in therapeutics for the treatment of liver cancer.

Calotropis gigantea stem bark extracts inhibit liver cancer induced by diethylnitrosamine

Several fractions of Calotropis gigantea extracts have been proposed to have potential anticancer activity in many cancer models. The present study evaluated the anticancer activity of C. gigantea stem bark extracts in liver cancer HepG2 cells and diethylnitrosamine (DEN)-induced primary liver cancer in rats. The carcinogenesis model induced by DEN administration has been widely used to study pathophysiological features and responses in rats that are comparable to those seen in cancer patients. The dichloromethane (CGDCM), ethyl acetate, and water fractions obtained from partitioning crude ethanolic extract were quantitatively analyzed for several groups of secondary metabolites and calactin contents. A combination of C. gigantea stem bark extracts with doxorubicin (DOX) was assessed in this study to demonstrate the enhanced cytotoxic effect to cancer compared to the single administration. The combination of DOX and CGDCM, which had the most potential cytotoxic effect in HepG2 cells when compared to the other three fractions, significantly increased cytotoxicity through the apoptotic effect with increased caspase-3 expression. This combination treatment also reduced ATP levels, implying a correlation between ATP and apoptosis induction. In a rat model of DEN-induced liver cancer, treatment with DOX, C. gigantea at low (CGDCM-L) and high (CGDCM-H) doses, and DOX + CGDCM-H for 4 weeks decreased the progression of liver cancer by lowering the liver weight/body weight ratio and the occurrence of liver hyperplastic nodules, fibrosis, and proliferative cells. The therapeutic applications lowered TNF-α, IL-6, TGF-β, and α-SMA inflammatory cytokines in a similar way, implying that CGDCM had a curative effect against the inflammation-induced liver carcinogenesis produced by DEN exposure. Furthermore, CGDCM and DOX therapy decreased ATP and fatty acid synthesis in rat liver cancer, which was correlated with apoptosis inhibition. CGDCM reduced cleaved caspase-3 expression in liver cancer rats when used alone or in combination with DOX, implying that apoptosis-inducing hepatic carcinogenesis was suppressed. Our results also verified the low toxicity of CGDCM injection on the internal organs of rats. Thus, this research clearly demonstrated a promising, novel anticancer approach that could be applied in future clinical studies of CGDCM and combination therapy.

Metabotropic glutamate receptors and nitric oxide in dopaminergic neurotoxicity

Dopaminergic neurotoxicity is characterized by damage and death of dopaminergic neurons. Parkinson's disease (PD) is a neurodegenerative disorder that primarily involves the loss of dopaminergic neurons in the substantia nigra. Therefore, the study of the mechanisms, as well as the search for new targets for the prevention and treatment of neurodegenerative diseases, is an important focus of modern neuroscience. PD is primarily caused by dysfunction of dopaminergic neurons; however, other neurotransmitter systems are also involved. Research reports have indicated that the glutamatergic system is involved in different pathological conditions, including dopaminergic neurotoxicity. Over the last two decades, the important functional interplay between dopaminergic and glutamatergic systems has stimulated interest in the possible role of metabotropic glutamate receptors (mGluRs) in the development of extrapyramidal disorders. However, the specific mechanisms driving these processes are presently unclear. The participation of the universal neuronal messenger nitric oxide (NO) in the mechanisms of dopaminergic neurotoxicity has attracted increased attention. The current paper aims to review the involvement of mGluRs and the contribution of NO to dopaminergic neurotoxicity. More precisely, we focused on studies conducted on the rotenone-induced PD model. This review is also an outline of our own results obtained using the method of electron paramagnetic resonance, which allows quantitation of NO radicals in brain structures.

Rotenone restrains the proliferation, motility and epithelial-mesenchymal transition of colon cancer cells and the tumourigenesis in nude mice via PI3K/AKT pathway

Rotenone, a toxic rotenoid compound, has anti-tumour effects on several cancers. This study aims to clarify the effect of rotenone on the proliferation, apoptosis, invasion and migration of colon cancer cells and tumourigenesis in nude mice. The present results show that rotenone significantly inhibited the proliferation, promoted the apoptosis, and suppressed the invasion and migration of colon cancer cells in a dose-dependent manner. Rotenone inhibited PI3K/AKT pathway in LoVo and SW480 cells in a dose-dependent manner. In addition, rotenone regulated the proliferation, apoptosis, invasion, migration and EMT of LoVo and SW480 cells through PI3K/AKT pathway. In colon cancer xenograft mice, rotenone inhibited tumour volume and weight in nude mice, inhibited PI3K/AKT pathway and EMT in vivo. Therefore, rotenone inhibited the proliferation, invasion and migration, promoted the apoptosis of colon cancer cells through PI3K/AKT pathway in vitro, and suppressed the tumourigenesis in nude mice in vivo.