Normal Cell Carcinogenesis Research Articles

Nrf2, A Target for Precision Oncology in Cancer Prognosis and Treatment.

Activating nuclear factor-erythroid 2-related factor (Nrf2), a master regulator of redox homeostasis, has been shown to suppress initiation of carcinogenesis in normal cells. However, this transcription factor has recently been reported to promote proliferation of some transformed or cancerous cells. In tumor cells, Nrf2 is prone to mutations that result in stabilization and concurrent accumulation of its protein product. A hyperactivated mutant form of Nrf2 could support the cancer cells for enhanced proliferation, invasiveness, and resistance to chemotherapeutic agents and radiotherapy, which are associated with a poor clinical outcome. Hence understanding mutations in Nrf2 would have a significant impact on the prognosis and treatment of cancer in the era of precision medicine. This perspective would provide an insight into the genetic alterations in Nrf2 and suggest the application of small molecules, RNAi, and genome editing technologies, particularly CRISR-Cas9, in therapeutic intervention of cancer in the context of the involvement of Nrf2 mutations.

Tumor Promoting Effects of Sulforaphane on Diethylnitrosamine-Induced Murine Hepatocarcinogenesis.

Nuclear factor erythroid 2-related factor 2 (NRF2) is a key transcription factor involved in protection against initiation of carcinogenesis in normal cells. Notably, recent studies have demonstrated that aberrant activation of NRF2 accelerates the proliferation and progression of cancer cells. The differential effects of NRF2 on multi-stage carcinogenesis have raised a concern about the validity of NRF2 activators for chemoprevention. This prompted us to assess the effects of sulforaphane (SFN), a prototypic NRF2 activating chemopreventive phytochemical, on experimentally induced carcinogenesis. In the present study, SFN was daily injected intraperitoneally (25 mg/kg) for 3 months to male C57BL/6 mice at 6 months after single intraperitoneal administration of a hepatocarcinogen, diethylnitrosamine (DEN). The liver to body weight ratio, tumor growth, and the number and the size of hepatomas measured at 9 months after DEN administration were significantly higher in SFN-treated mice than those in vehicle-treated mice. Moreover, the expression of NRF2, its target protein NAD(P)H:quinone oxidoreductase 1, and the cell proliferation marker, proliferating cell nuclear antigen was further elevated in DEN plus SFN-treated mice. These results suggest that once hepatocarcinogenesis is initiated, SFN may stimulate tumor progression.

CRISPR/Cas9 in epigenetics studies of health and disease.

Epigenetics is the heritable phenotypic changes without altering the genotype. Epigenetic processes are such as histone methylation, acetylation, ubiquitination, sumoylation, phosphorylation, ADP ribosylation, DNA methylation and non-coding RNAs interactions associated with structural changes in chromatin. The change of structure is either open chromatin for "active" state or closed chromatin for "inactive" state, that regulates important biological phenomenon like chromatin condensation, gene expression, DNA repair, cellular development, differentiation and homeostasis, etc. However, dysregulation of epigenetic patterns causes diseases like cancer, diabetes, neurological disorder, infectious diseases, autoimmunity etc. Besides, the most important clinical uses of Epigenetics studies are i. identification of disease biomarkers and ii. development of their therapeutics. Epigenetic therapies include epi-drugs, combinatorial therapy, nanocarriers, plant-derived products that are being used for changing the epigenetic pattern to reverse gene expression. However, the developed epi- drugs cause off-target gene and transposable elements activation; promote mutagenesis and carcinogenesis in normal cells, are the major hurdles regarding their clinical use. Therefore, advanced epigenetic therapeutics are required to develop target-specific epigenetic modifications to reverse gene expression pattern. CRISPR-Cas9 (Clustered Regularly Interspaced Palindrome Repeats-associated protein 9) system-mediated gene activation mechanism paves new methods of target-specific epigenetic therapeutics to cure diseases. In this chapter, we discuss how CRISPR/Cas9 and dCas9 have recently been engineered for epigenome editing. Different strategies have been discussed used for epigenome editing based on their efficacy and complexity. Last but not least we have discussed the limitations, different uses of CRISPR/Cas9 and dCas9 in the area of genetic engineering.

Abstract 3828: Tumor promoting effects of sulforaphane on diethylnitrosamine-induced murine hepatocarcinogenesis

Abstract Nuclear factor erythroid 2-related factor 2 (NRF2) is a key transcription factor involved in protection against initiation of carcinogenesis in normal cells. Notably, recent studies have demonstrated that mutation of the gene encoding this transcription factor causes its overactivation in various types of human malignancies. The aberrant activation of NRF2 is considered to accelerate the proliferation and progression of cancer cells. However, the exact function of NRF2 in the stage of pre-malignancy remains still largely unresolved. The differential effects of NRF2 on multi-stage carcinogenesis have raised a concern about the validity of NRF2 activators for chemoprevention. In the present study, a well-known NRF2 activating chemopreventive phytochemical, sulforaphane (SFN), was daily injected intraperitonally (25 mg/kg) for 3 months to male C57BL/6 mice at 6 months after single intraperitoneal administration of a hepatocarcinogen, diethylnitrosamine (DEN). The relative fold changes of liver weight, tumor growth, and the number and the size of hepatomas measured at 9 months after DEN administration were significantly higher in SFN-treated mice than that in vehicle-treated mice. Moreover, the expression of NRF2, its target protein NAD(P)H:quinone oxidoreductase 1 (NQO1), and the cell proliferation marker proliferating cell nuclear antigen (PCNA) and the DNA damage marker gamma-histone 2A family member X (γH2AX) was markedly elevated in SFN-treated mice compared with that in vehicle-treated mice as assessed by the Western blot assay. Immunohistochemistry and Immunofluorescence staining data further verified higher expression of NRF2 and PCNA in SFN-treated mice. These results suggest that once HCC is initiated, SFN stimulates the progression of DEN-induced HCC via activation of NRF2, rather than exerting a cancer chemopreventive effect. RNA sequencing analysis with liver tumors from DEN-treated mice revealed the B-raf V637E mutation (4/7). We speculate that mutation of B-raf proto-oncogene may contribute, at least in part, to activation of oncogenic NRF2 in DEN-induced murine carcinogenesis. The effects of SFN on DEN-induced mutation spectrum is under investigation. This study was supported by the Global Core Research Center (GCRC) Grant (No. 2011-003-0001) from the National Research Foundation (NRF) of Republic of Korea. Citation Format: Jie Zheng, Do-Hee Kim, Xi Zhu Fang, Seong Hoon Kim, Soma Saeidi, Su-Jung Kim, Young-Joon Surh. Tumor promoting effects of sulforaphane on diethylnitrosamine-induced murine hepatocarcinogenesis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3828.

BRCA1 and Oxidative Stress.

The breast cancer susceptibility gene 1 (BRCA1) has been well established as a tumor suppressor and functions primarily by maintaining genome integrity. Genome stability is compromised when cells are exposed to oxidative stress. Increasing evidence suggests that BRCA1 regulates oxidative stress and this may be another mechanism in preventing carcinogenesis in normal cells. Oxidative stress caused by reactive oxygen species (ROS) is implicated in carcinogenesis and is used strategically to treat human cancer. Thus, it is essential to understand the function of BRCA1 in oxidative stress regulation. In this review, we briefly summarize BRCA1’s many binding partners and mechanisms, and discuss data supporting the function of BRCA1 in oxidative stress regulation. Finally, we consider its significance in prevention and/or treatment of BRCA1-related cancers.

TNF-α −308 genotypes are associated with TNF-α and TGF-β 1 mRNA expression in blood leucocytes of humans

Aim Tumor necrosis factor α (TNF-α) influences the pathogenesis of lung-fibrosis and carcinogenesis in normal cells. Polymorphisms of this gene are suggested to be associated with susceptibility to lung-diseases. Additionally TNF-α is postulated to play a significant role in regulating. Transforming growth factor (TGF-β 1) expression Therefore we investigated if the TNF-α or TGF-β 1 gene expression level is different within the −308 TNF-α genotypes. Methods Quantitative Real-time PCR of TNF-α and TGF-β 1 was performed in 178 Germans. Calculations of expression were made with the 2 −ΔΔCT method. Detection of the −308 promoter polymorphism of the TNF-α gene was performed by rapid capillary PCR with melting curve analysis. Results The relative TNF-α mRNA expression revealed significant differences between the TNF-α −308 homozygote wild-type G/G (0.00079 ± 0.00011; n = 113) and the heterozygote genotype G/A (0.0005 ± 0.00008; n = 52; p = 0.030) as well as between homozygote wild-type G/G and the homozygote mutant A/A (0.00029 ± 0.00009; n = 5; p = 0.004). The relative TGF-β mRNA expression showed, similar to TNF-α, the highest mRNA expression was seen within the TNF-α −308 homozygote wild-types, while the lowest mRNA expression lay within the homozygote mutant-types. Conclusion Our findings suggest that the G-allele of TNF-α −308 is associated with a significantly higher TNF-α mRNA expression compared to the A-allele and that this also reflects in TGF-β expression. Therefore we support the thesis that TGF-β is regulated by TNF-α.

Tumour necrosis factor-α gene polymorphisms in asbestos-induced diseases

Background: Tumour necrosis factor (TNF)-α influences the pathogenesis of lung fibrosis and carcinogenesis in normal cells. Polymorphisms of this gene have been suggested to be associated with susceptibility to lung diseases.Methods: Association studies were performed in German subjects, using control subjects (n = 177), pulmonary fibrosis patients (n = 612) and bronchial carcinoma patients (n = 374).Results: Compared with a healthy (control) group, a significant result could be obtained for the asbestosis (patient) group (crude odds ratio (ORcrude) = 1.57; 95% confidence interval (CI) 1.05–2.36; p = 0.03), especially with severe lung asbestosis (ORcrude = 4.15; 95% CI 1.06–16.16; p = 0.04). A significant association was revealed when comparing asbestosis patients (ORcrude = 4.08; 95% CI 1.53–10.54; p = 0.004 and ORadjusted = 3.89; 95% CI 1.49–10.17; p = 0.006) with asbestos-induced lung cancer patients.Conclusion: The results confirm the hypothesis that TNF-α polymorphisms are associated with asbestos-induced fibrotic or malignant lung diseases in Germans.

Anticarcinogenesis by dietary phytochemicals: Cytoprotection by Nrf2 in normal cells and cytotoxicity by modulation of transcription factors NF-κB and AP-1 in abnormal cancer cells

Cancer statistics from the American Cancer Society and other sources are a stark reminder of our failure to combat this deadly disease. Chemoprevention entails the use of specific naturally occurring dietary or synthetic agents to thwart cancer development and progression. Some of these agents are believed to do so by protecting the cells or tissues from the malicious attack of exogenous carcinogens and/or endogenous reactive oxygen/nitrogen species (RONS) by inducing several detoxifying/antioxidant enzymes that appear to form stable conjugates such as glutathione, glucuronides or sulfates thus rendering the carcinogenic species harmless. This process of inducing the cellular defense enzymes is believed to be mediated by the antioxidant response elements (ARE) within the promoter regions of these genes. Nrf2, a redox sensitive transcription factor has been documented to play a central role in ARE-driven gene expression. Nrf2, under normal unstimulated conditions, remains sequestered in the cytosol by Keap1. The putative chemopreventive agents disrupt the Nrf2-Keap1 association, thereby releasing Nrf2 which then translocates to the nucleus and drives the gene expression of detoxifying enzymes. The role of other transcription factors such as NF-κB and AP-1 in carcinogenesis is well established. By modulating the activity of these transcription factors and their upstream signaling molecules, naturally occurring dietary phytochemicals appear to cause apoptosis in abnormal cells that over-express these factors, thereby inhibiting the promotion and progression. This review discusses the most current and up to date understanding of the possible signaling mechanisms by which these naturally dietary phytochemicals can differentially modulate signal transduction cascades such that they can bring about apoptosis/cell death in abnormal cancer cells but at the same time induce defensive enzymes to protect against carcinogenesis in normal cells.

Management of coastal communities: A. J. Gray, in: The scientific management of temperate communities for conservation. 31st symposium of the British Ecological Society, Southampton, 1989, ed I.F. Spellerberg & others, (Blackwell Scientific, for BES), 1991, pp 227–243

Tumor necrosis factor α (TNF-α) influences the pathogenesis of lung-fibrosis and carcinogenesis in normal cells. Polymorphisms of this gene are suggested to be associated with susceptibility to lung-diseases. Additionally TNF-α is postulated to play a significant role in regulating. Transforming growth factor (TGF-β1) expression Therefore we investigated if the TNF-α or TGF-β1 gene expression level is different within the −308 TNF-α genotypes.Quantitative Real-time PCR of TNF-α and TGF-β1 was performed in 178 Germans. Calculations of expression were made with the 2−ΔΔCT method. Detection of the −308 promoter polymorphism of the TNF-α gene was performed by rapid capillary PCR with melting curve analysis.The relative TNF-α mRNA expression revealed significant differences between the TNF-α −308 homozygote wild-type G/G (0.00079 ± 0.00011; n = 113) and the heterozygote genotype G/A (0.0005 ± 0.00008; n = 52; p = 0.030) as well as between homozygote wild-type G/G and the homozygote mutant A/A (0.00029 ± 0.00009; n = 5; p = 0.004). The relative TGF-β mRNA expression showed, similar to TNF-α, the highest mRNA expression was seen within the TNF-α −308 homozygote wild-types, while the lowest mRNA expression lay within the homozygote mutant-types.Our findings suggest that the G-allele of TNF-α −308 is associated with a significantly higher TNF-α mRNA expression compared to the A-allele and that this also reflects in TGF-β expression. Therefore we support the thesis that TGF-β is regulated by TNF-α.

Analysis of polygamous systems using DNA fingerprinting: B. Amos, in: Biotechnology and the conservation of genetic diversity. Proc. symposium, London, 1990, ed H.D.M. Moore & others, (Clarendon Press, for Zoological Society of London; Symposia of the Zoological Society of London, 64), 1992, pp 151–165

Tumor necrosis factor α (TNF-α) influences the pathogenesis of lung-fibrosis and carcinogenesis in normal cells. Polymorphisms of this gene are suggested to be associated with susceptibility to lung-diseases. Additionally TNF-α is postulated to play a significant role in regulating. Transforming growth factor (TGF-β1) expression Therefore we investigated if the TNF-α or TGF-β1 gene expression level is different within the −308 TNF-α genotypes.Quantitative Real-time PCR of TNF-α and TGF-β1 was performed in 178 Germans. Calculations of expression were made with the 2−ΔΔCT method. Detection of the −308 promoter polymorphism of the TNF-α gene was performed by rapid capillary PCR with melting curve analysis.The relative TNF-α mRNA expression revealed significant differences between the TNF-α −308 homozygote wild-type G/G (0.00079 ± 0.00011; n = 113) and the heterozygote genotype G/A (0.0005 ± 0.00008; n = 52; p = 0.030) as well as between homozygote wild-type G/G and the homozygote mutant A/A (0.00029 ± 0.00009; n = 5; p = 0.004). The relative TGF-β mRNA expression showed, similar to TNF-α, the highest mRNA expression was seen within the TNF-α −308 homozygote wild-types, while the lowest mRNA expression lay within the homozygote mutant-types.Our findings suggest that the G-allele of TNF-α −308 is associated with a significantly higher TNF-α mRNA expression compared to the A-allele and that this also reflects in TGF-β expression. Therefore we support the thesis that TGF-β is regulated by TNF-α.

Short-term dynamics of a neotropical forest: why ecological research matters to tropical conservation and management: S. P. Hubbell & R. B. Foster, Oikos, 63(1), 1992, pp 48–61

Tumor necrosis factor α (TNF-α) influences the pathogenesis of lung-fibrosis and carcinogenesis in normal cells. Polymorphisms of this gene are suggested to be associated with susceptibility to lung-diseases. Additionally TNF-α is postulated to play a significant role in regulating. Transforming growth factor (TGF-β1) expression Therefore we investigated if the TNF-α or TGF-β1 gene expression level is different within the −308 TNF-α genotypes.Quantitative Real-time PCR of TNF-α and TGF-β1 was performed in 178 Germans. Calculations of expression were made with the 2−ΔΔCT method. Detection of the −308 promoter polymorphism of the TNF-α gene was performed by rapid capillary PCR with melting curve analysis.The relative TNF-α mRNA expression revealed significant differences between the TNF-α −308 homozygote wild-type G/G (0.00079 ± 0.00011; n = 113) and the heterozygote genotype G/A (0.0005 ± 0.00008; n = 52; p = 0.030) as well as between homozygote wild-type G/G and the homozygote mutant A/A (0.00029 ± 0.00009; n = 5; p = 0.004). The relative TGF-β mRNA expression showed, similar to TNF-α, the highest mRNA expression was seen within the TNF-α −308 homozygote wild-types, while the lowest mRNA expression lay within the homozygote mutant-types.Our findings suggest that the G-allele of TNF-α −308 is associated with a significantly higher TNF-α mRNA expression compared to the A-allele and that this also reflects in TGF-β expression. Therefore we support the thesis that TGF-β is regulated by TNF-α.