• Archives of Pharmacal Research
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• 제27권7호
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• pp.683-692
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• 2004

Curcumin (diferuloylmethane) is a major naturally-occurring polyphenol of Curcuma species, which is commonly used as a yellow coloring and flavoring agent in foods. Curcumin has shown anti-carcinogenic activity in animal models. Curcumin possesses anti-inflammatory activity and is a potent inhibitor of reactive oxygen-generating enzymes such as lipoxygenase/cyclooxygenase, xanthine dehydrogenase/oxidase and inducible nitric oxide synthase; and an effective inducer of heme oxygenase-1. Curcumin is also a potent inhibitor of protein kinase C(PKC), EGF(Epidermal growth factor)-receptor tyrosine kinase and LĸB kinase. Subsequently, curcumin inhibits the activation of NF(nucleor factor)KB and the expressions of oncogenes including c-jun, c-fos, c-myc, NIK, MAPKs, ERK, ELK, PI3K, Akt, CDKs and iNOS. It is proposed that curcumin may suppress tumor promotion through blocking signal transduction path-ways in the target cells. The oxidant tumor promoter TPA activates PKC by reacting with zinc thiolates present within the regulatory domain, while the oxidized form of cancer chemopreventive agent such as curcumin can inactivate PKC by oxidizing the vicinal thiols present within the catalytic domain. Recent studies indicated that proteasome-mediated degradation of cell proteins playa pivotal role in the regulation of several basic cellular processes including differentiation, proliferation, cell cycling, and apoptosis. It has been demonstrated that curcumin-induced apoptosis is mediated through the impairment of ubiquitin-proteasome pathway. Curcumin was first biotransformed to dihydrocurcumin and tetrahydrocurcumin and that these compounds subsequently were converted to monoglucuronide conjugates. These results suggest that curcumin-glucuronide, dihydrocurcumin-glucuronide, tetrahydrocurcumin-glucuronide and tetrahydrocurcumin are the major metabolites of curcumin in mice, rats and humans.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8247-8252
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• 2016

Background: The ubiquitin-proteasome system (UPS) degrades a variety of proteins which attach to specific signals. The ubiquitination pathway facilitates degradation of damaged proteins and regulates growth and stress responses. This pathway is altered in various cancers, including acute lymphoblastic leukemia, head and neck squamous cell carcinoma and breast cancer. Recently it has been reported that expression of newly characterized human genes, UBE2Q1 and UBE2Q2, putative members of ubiquitin-conjugating enzyme family (E2), has been also changed in colorectal cancer. Epigenetics is one of the fastest-growing areas of science and nowadays has become a central issue in biological studies of diseases. According to the lack of information about the role of epigenetic changes on gene expression profiling of UBE2Q1 and UBE2Q2, and the presence of CpG islands in the promoter of these two human genes, we decided to evaluate the promoter methylation status of these genes as a first step. Materials and Methods: The promoter methylation status of UBE2Q1 and UBE2Q2 was studied by methylation-specific PCR (MSP) in tumor samples of 60 colorectal cancer patients compared to adjacent normal tissues and 20 non-malignant controls. The frequency of the methylation for each gene was analyzed by chi-square method. Results: MSP results revealed that UBE2Q2 gene promoter were more unmethylated, while a higher level of methylated allele was observed for UBE2Q1 in tumor tissues compared to the adjacent normal tissues and the non malignant controls. Conclusions: UBE2Q1 and UBE2Q2 genes show different methylation profiles in CRC cases.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8271-8279
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• 2016

Background: Hepato-carcinogenesis is multifaceted in its molecular aspects. Among the interplaying agents are altered gap junctions, the proteasome/autophagy system, and mitochondria. The present experimental study was designed to outline the roles of these players and to investigate the tumor suppressive effects of curcumin with or without mesenchymal stem cells (MSCs) in hepatocellular carcinoma (HCC). Materials and Methods: Adult female albino rats were divided into normal controls and animals with HCC induced by diethyl-nitrosamine (DENA) and $CCl_4$. Additional groups treated after HCC induction were: Cur/HCC which received curcumin; MSCs/HCC which received MSCs; and Cur+MSCs/HCC which received both curcumin and MSCs. For all groups there were histopathological examination and assessment of gene expression of connexin43 (Cx43), ubiquitin ligase-E3 (UCP-3), the autophagy marker LC3 and coenzyme-Q10 (Mito.Q10) mRNA by real time, reverse transcription-polymerase chain reaction, along with measurement of LC3II/LC3I ratio for estimation of autophagosome formation in the rat liver tissue. In addition, the serum levels of ALT, AST and alpha fetoprotein (AFP), together with the proinflammatory cytokines $TNF{\alpha}$ and IL-6, were determined in all groups. Results: Histopathological examination of liver tissue from animals which received DENA-$CCl_4$ only revealed the presence of anaplastic carcinoma cells and macro-regenerative nodules. Administration of curcumin, MSCs; each alone or combined into rats after induction of HCC improved the histopathological picture. This was accompanied by significant reduction in ${\alpha}$-fetoprotein together with proinflammatory cytokines and significant decrease of various liver enzymes, in addition to upregulation of Cx43, UCP-3, LC3 and Mito.Q10 mRNA. Conclusions: Improvement of Cx43 expression, nonapoptotic cell death and mitochondrial function can repress tumor growth in HCC. Administration of curcumin and/or MSCs have tumor suppressive effects as they can target these mechanisms. However, further research is still needed to verify their effectiveness.

• Asian Pacific Journal of Cancer Prevention
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• 제14권7호
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• pp.4279-4282
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• 2013

Background: The activation and inactivation of receptor tyrosine kinases are tightly regulated to ensure faithful replication of cells. After having transduced extracellular growth activating signals, activated EGFR is subjected to downregulation either by clathrin mediated endocytosis or c-Cbl mediated proteasome degradation depending on the ligand concentration. c-Cbl is an ubiquitin ligase which requires a phosphorylated tyrosine residue at position 1045 in the cytoplasmic domain of EGFR to interact and add ubiquitin molecules. While activating mutations in exons 19 and 21 have been associated with the development of several cancers, the status of mutations at tyrosine 1045 coding exon 27 of EGFR remain to be investigated. Consistently, defective phosphorylation at 1045 has been associated with sustained phosphorylation of EGFR in non-small lung carcinomas. Hence in the present study we investigated the genetic status of the tyrosine 1045 coding site within exon 27 of EGFR gene to explore for possible occurrence of mutations in this region, especially since no studies have addressed this issue so far. Materials and Methods: Tumor chromosomal DNA isolated from thirty five surgically excised oral squamous cell carcinoma tissues was subjected to PCR amplification with intronic primers flanking the tyrosine 1045 coding exon 27 of EGFR gene. The PCR amplicons were subsequently subjected to direct sequencing to elucidate the mutation status. Results: Sequence analysis identified no mutations in the tyrosine 1045 codon of EGFR in any of the thirty five samples that were analyzed. Conclusions: The lack of identification of mutation in the tyrosine 1045 codon of EGFR suggests that mutations in this region may be relatively rare in oral squamous cell carcinomas. To the best of our knowledge, this study is the first to have explored the genetic status of exon 27 of EGFR in oral squamous cell carcinoma tissue samples.

• Molecules and Cells
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• 제45권6호
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• pp.425-434
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• 2022

The post-translational modification (e.g., phosphorylation) of estrogen receptor α (ERα) plays a role in controlling the expression and subcellular localization of ERα as well as its sensitivity to hormone response. Here, we show that ERα is also modified by UFM1 and this modification (ufmylation) plays a crucial role in promoting the stability and transactivity of ERα, which in turn promotes breast cancer development. The elevation of ufmylation via the knockdown of UFSP2 (the UFM1-deconjugating enzyme in humans) dramatically increases ERα stability by inhibiting ubiquitination. In contrast, ERα stability is decreased by the prevention of ufmylation via the silencing of UBA5 (the UFM1-activating E1 enzyme). Lys171 and Lys180 of ERα were identified as the major UFM1 acceptor sites, and the replacement of both Lys residues by Arg (2KR mutation) markedly reduced ERα stability. Moreover, the 2KR mutation abrogated the 17β-estradiol-induced transactivity of ERα and the expression of its downstream target genes, including pS2, cyclin D1, and c-Myc; this indicates that ERα ufmylation is required for its transactivation function. In addition, the 2KR mutation prevented anchorage-independent colony formation by MCF7 cells. Most notably, the expression of UFM1 and its conjugating machinery (i.e., UBA5, UFC1, UFL1, and UFBP1) were dramatically upregulated in ERα-positive breast cancer cell lines and tissues. Collectively, these findings implicate a critical role attributed to ERα ufmylation in breast cancer development by ameliorating its stability and transactivity.

• Molecules and Cells
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• 제45권10호
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• pp.695-701
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• 2022

Homeostatic regulation of meristematic stem cells accomplished by maintaining a balance between stem cell self-renewal and differentiation is critical for proper plant growth and development. The quiescent center (QC) regulates root apical meristem homeostasis by maintaining stem cell fate during plant root development. Cell cycle checkpoints, such as anaphase promoting complex/cyclosome/cell cycle switch 52 A2 (APC/C^CCS52A2), strictly control the low proliferation rate of QC cells. Although APC/C^CCS52A2 plays a critical role in maintaining QC cell division, the molecular mechanism that regulates its activity remains largely unknown. Here, we identified SCF^FBS1, a ubiquitin E3 ligase, as a key regulator of QC cell division through the direct proteolysis of CCS52A2. FBS1 activity is positively associated with QC cell division and CCS52A2 proteolysis. FBS1 overexpression or ccs52a2-1 knockout consistently resulted in abnormal root development, characterized by root growth inhibition and low mitotic activity in the meristematic zone. Loss-of-function mutation of FBS1, on the other hand, resulted in low QC cell division, extremely low WOX5 expression, and rapid root growth. The 26S proteasome-mediated degradation of CCS52A2 was facilitated by its direct interaction with FBS1. The FBS1 genetically interacted with APC/C^CCS52A2-ERF115-PSKR1 signaling module for QC division. Thus, our findings establish SCF^FBS1-mediated CCS52A2 proteolysis as the molecular mechanism for controlling QC cell division in plants.

• Molecules and Cells
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• 제27권3호
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• pp.359-363
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• 2009

Chfr, a checkpoint with FHA and RING finger domains, plays an important role in cell cycle progression and tumor suppression. Chfr possesses the E3 ubiquitin ligase activity and stimulates the formation of polyubiquitin chains by Ub-conjugating enzymes, and induces the proteasome-dependent degradation of a number of cellular proteins, including Plk1 and Aurora A. While Chfr is a nuclear protein that functions within the cell nucleus, how Chfr is localized in the nucleus has not been clearly demonstrated. Here, we show that nuclear localization of Chfr is mediated by nuclear localization signal (NLS) sequences. To reveal the signal sequences responsible for nuclear localization, a short lysine-rich stretch (KKK) at amino acid residues 257-259 was replaced with alanine, which completely abolished nuclear localization. Moreover, we show that nuclear localization of Chfr is essential for its checkpoint function but not for its stability. Thus, our results suggest that NLS-mediated nuclear localization of Chfr leads to its accumulation within the nucleus, which may be important in the regulation of Chfr activation and Chfr-mediated cellular processes, including cell cycle progression and tumor suppression.

• Molecules and Cells
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• 제39권8호
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• pp.581-586
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• 2016

Post-translational modifications (PTMs) of proteins are essential to increase the functional diversity of the proteome. By adding chemical groups to proteins, or degrading entire proteins by phosphorylation, glycosylation, ubiquitination, neddylation, acetylation, lipidation, and proteolysis, the complexity of the proteome increases, and this then influences most biological processes. Although small RNAs are crucial regulatory elements for gene expression in most eukaryotes, PTMs of small RNA microprocessor and RNA silencing components have not been extensively investigated in plants. To date, several studies have shown that the proteolytic regulation of AGOs is important for host-pathogen interactions. DRB4 is regulated by the ubiquitin-proteasome system, and the degradation of HYL1 is modulated by a de-etiolation repressor, COP1, and an unknown cytoplasmic protease. Here, we discuss current findings on the PTMs of microprocessor and RNA silencing components in plants.

• Tuberculosis and Respiratory Diseases
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• 제68권3호
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• pp.125-139
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• 2010

Patients with chronic obstructive pulmonary disease (COPD) frequently complain of dyspnea on exertion and reduced exercise capacity, which has been attributed to an increase in the work of breathing and in impaired of gas exchange. Although COPD primarily affects the pulmonary system, patients with COPD exhibit significant systemic manifestations of disease progression. These manifestations include weight loss, nutritional abnormalities, skeletal muscle dysfunction (SMD), cardiovascular problems, and psychosocial complications. It has been documented that SMD significantly contributes to a reduced exercise capacity in patients with COPD. Ventilatory and limb muscle in these patients show structural and functional alteration, which are influenced by several factors, including physical inactivity, hypoxia, smoking, aging, corticosteroid, malnutrition, systemic inflammation, oxidative stress, apoptosis, and ubiquitin-proteasome pathway activation. This article summarizes briefly the evidence and the clinical consequences of SMD in patients with COPD. In addition, it reviews contributing factors and therapeutic strategies.

• Molecules and Cells
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• 제43권1호
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• pp.76-85
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• 2020

MARCH5 is a RING finger E3 ligase involved in mitochondrial integrity, cellular protein homeostasis, and the regulation of mitochondrial fusion and fission. To determine the function of MARCH5 during development, we assessed transcript expression in zebrafish embryos. We found that march5 transcripts were of maternal origin and evenly distributed at the 1-cell stage, except for the mid-blastula transition, with expression predominantly in the developing central nervous system at later stages of embryogenesis. Overexpression of march5 impaired convergent extension movement during gastrulation, resulting in reduced patterning along the dorsoventral axis and alterations in the ventral cell types. Overexpression and knockdown of march5 disrupted the organization of the developing telencephalon and diencephalon. Lastly, we found that the transcription of march5 was tightly regulated by the transcriptional regulators CHOP, C/EBPα, Staf, Znf143a, and Znf76. These results demonstrate the essential role of March5 in the development of zebrafish embryos.