Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0345904 (liver cancer)
 15,188 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Microcystins (MCs) are hepatotoxins produced by a variety of freshwater cyanobacteria. The toxicity of these hepatotoxins is a severe health issue for both humans and livestock; MCs have been implicated in the development of liver cancer, necrosis, and even deadly intrahepatic bleeding. Microcystin-LR (MC-LR) is the MC variant most commonly encountered in a contaminated aquatic system. Thus far, MC-LR has only been shown to target the serine/threonine protein phosphatases 1 and 2A (PP1 and PP2A) and it is still unknown whether MC-LR can bind and inhibit any other protein targets inside the cell. To find potential MC-LR targets, we screened a phage display library for peptide ligands that specifically recognize MC-LR. Using these peptide sequences as guides, we performed a series of bioinformatics analyses revealing that MC-LR binds human liver aldehyde dehydrogenase 2 (ALDH2) at residues 447-451. We confirmed MC-LR binding of ALDH2 via automated docking computation, which yielded results matching our experimental and bioinformatics analyses. ALDH2 dysfunction may lead to aldehyde-induced reactive oxygen species (ROS) generation and, in turn, apoptosis. Therefore, ALDH2 could potentially be a target of MC-LR associated with the process of ROS-induced apoptosis. Our current study presents a new approach to the study of interactions of biological molecules by combining phage display technology with computational methods.
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PMID:Identification of human liver mitochondrial aldehyde dehydrogenase as a potential target for microcystin-LR. 1641 48

Microcystin-LR (MC-LR) is a potent heptapeptide hepatotoxin at high doses, but its underlying mechanism of promoting liver cell proliferation at low doses is unclear. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is key in mediating the protective antioxidant response against various environmental toxicants, but emerging data suggest that constitutive activation of Nrf2 contributes to a malignant phenotype. The purpose of this study was to characterize the interactions and effects of Nrf2 activation on cell proliferation induced by MC-LR treatment. Treatment of HepG2 and Hep3B cells with MC-LR resulted in significant increases in Nrf2-ARE binding activities in the nuclear fractions and upregulation of its downstream genes HO-1 and NQO1. A possible mechanism may be that MC-LR binds to the cytosolic regulator protein Keap1 to liberate Nrf2. Nrf2 knockdown inhibited MC-LR-induced cell proliferation and cell cycle progression. Together, these results indicate that MC-LR-induced upregulation of Nrf2 in cancer cells promotes liver cancer cell growth and suggest a positive role of Nrf2 in tumorigenesis.
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PMID:Activation of Nrf2 by microcystin-LR provides advantages for liver cancer cell growth. 2072 99

Microcystin-LR (MC-LR) is the most common and toxic hepatotoxin and it could induce human hepatitis and hepatocellular carcinoma (HCC) via the route of drinking water. The aim of the present study was to determine the expressions of oncogenes c-fos, c-jun, c-myc, c-met, and N-ras and tumor suppressor gene PTEN in HepG2 cells following MC-LR-exposure to understand the possible mechanism of MC-LR-related human primary liver cancer. The results of qPCR and Western blotting showed that MC-LR-exposure at non- or sub-cytotoxic concentrations promoted the expressions of oncogenes c-fos, c-jun, c-myc, c-met, and N-ras while suppressed tumor-suppressor gene PTEN in HepG2 cells at both transcription and protein levels. This result suggests that HCC-related genes may be involved in human hepatitis and primary liver cancer caused by MC-LR. The work might be useful for evaluating the human health risk resulted from the long-term of MC-LR-exposure at low dose via drinking water route.
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PMID:Alterations in transcription and protein expressions of HCC-related genes in HepG2 cells caused by microcystin-LR. 2806 58