Expression of nuclear factor-kappaB family proteins in hepatocellular carcinomas

Targeting the NF-κB p65/Bcl-2 signaling pathway in hepatic cellular carcinoma using radiation assisted synthesis of zinc nanoparticles coated with naturally isolated gallic acid

PURPOSE

Oral diethylnitrosamine (DEN) is a known hepatocarcinogen that damages the liver and causes cancer. DEN damages the liver through reactive oxygen species-mediated inflammation and biological process regulation.

MATERIALS AND METHODS

Gallic acid-coated zinc oxide nanoparticles (Zn-GANPs) were made from zinc oxide (ZnO) synthesized by irradiation dose of 50 kGy utilizing a Co-60 γ-ray source chamber with a dose rate of 0.83 kGy/h and gallic acid from pomegranate peel. UV-visible (UV) spectrophotometry verified Zn-GANP synthesis. TEM, DLS, and FTIR were utilized to investigate ZnO-NPs' characteristics. Rats were orally exposed to DEN for 8 weeks at 20 mg/kg five times per week, followed by intraperitoneal injection of Zn-GANPs at 20 mg/kg for 5 weeks. Using oxidative stress, anti-inflammatory, liver function, histologic, apoptotic, and cell cycle parameters for evaluating Zn-GANPs treatment.

RESULTS

DEN exposure elevated inflammatory markers (AFP and NF-κB p65), transaminases (AST, ALT), γ-GT, globulin, and total bilirubin, with reduced protein and albumin levels. It also increased MDA levels, oxidative liver cell damage, and Bcl-2, while decreasing caspase-3 and antioxidants like GSH, and CAT. Zn-GANPs significantly mitigated these effects and lowered lipid peroxidation, AST, ALT, and γ-GT levels, significantly increased CAT and GSH levels (p<0.05). Zn-GANPs caused S and G2/M cell cycle arrest and G0/G1 apoptosis. These results were associated with higher caspase-3 levels and lower Bcl-2 and TGF-β1 levels. Zn-GANPs enhance and restore the histology and ultrastructure of the liver in DEN-induced rats.

CONCLUSION

The data imply that Zn-GANPs may prevent and treat DEN-induced liver damage and carcinogenesis.

Multifaceted roles for BCL3 in cancer: a proto-oncogene comes of age

In the early 1990's a group of unrelated genes were identified from the sites of recurring translocations in B-cell lymphomas. Despite sharing the nomenclature 'Bcl', and an association with blood-borne cancer, these genes have unrelated functions. Of these genes, BCL2 is best known as a key cancer target involved in the regulation of caspases and other cell viability mechanisms. BCL3 on the other hand was originally identified as a non-canonical regulator of NF-kB transcription factor pathways - a signaling mechanism associated with important cell outcomes including many of the hallmarks of cancer. Most of the early investigations into BCL3 function have since focused on its role in NF-kB mediated cell proliferation, inflammation/immunity and cancer. However, recent evidence is coming to light that this protein directly interacts with and modulates a number of other signaling pathways including DNA damage repair, WNT/β-catenin, AKT, TGFβ/SMAD3 and STAT3 - all of which have key roles in cancer development, metastatic progression and treatment of solid tumours. Here we review the direct evidence demonstrating BCL3's central role in a transcriptional network of signaling pathways that modulate cancer biology and treatment response in a range of solid tumour types and propose common mechanisms of action of BCL3 which may be exploited in the future to target its oncogenic effects for patient benefit.

Epigenetic Regulation in Breast Cancer

Aberrant epigenetic alteration has been associated with development of various cancers, including breast cancer. Since epigenetic modifications such as DNA methylation and histone modification are reversible, epigenetic enzymes, including histone modifying enzymes and DNA methyltransferases, emerge as attractive targets for cancer therapy. Although epi-drugs targeting histone deacetylation or DNA methylation have received FDA approval for cancer therapy, a very modest anti-tumor activity has been observed with monotherapy in clinical studies of breast cancer. To improve efficacy of epi-drugs in breast cancer, combination of epi-drugs with other therapies currently has been investigated. Additionally, basic researches to elucidate molecular causes of cancer should be extensively and intensively conducted in order to find novel epigenetic druggable targets. In this chapter, we summarize how epigenetic regulation affects the development of breast cancer and how to control cancer phenotype by modulating abnormal epigenetic modifications, and then suggest future research directions in epigenetics for breast cancer treatment.

HCV eradication with IFN-based therapy does not completely restore gene expression in PBMCs from HIV/HCV-coinfected patients

Objective

To evaluate the impact of hepatitis C virus (HCV) elimination via interferon (IFN)-based therapy on gene expression profiles related to the immune system in HIV/HCV-coinfected patients.

Methods

We conducted a prospective study in 28 HIV/HCV-coinfected patients receiving IFN-based therapy at baseline (HIV/HCV-b) and week 24 after sustained virological response (HIV/HCV-f). Twenty-seven HIV-monoinfected patients (HIV-mono) were included as a control. RNA-seq analysis was performed on peripheral blood mononuclear cells (PBMCs). Genes with a fold-change (FC) ≥ 1.5 (in either direction) and false discovery rate (FDR) ≤ 0.05 were identified as significantly differentially expressed (SDE).

Results

HIV/HCV-b showed six SDE genes compared to HIV-mono group, but no significantly enriched pathways were observed. For HIV/HCV-f vs. HIV/HCV-b, we found 58 SDE genes, 34 upregulated and 24 downregulated in the HIV/HCV-f group. Of these, the most overexpressed were CXCL2, PDCD6IP, ATP5B, IGSF9, RAB26, and CSRNP1, and the most downregulated were IFI44 and IFI44L. These 58 SDE genes revealed two significantly enriched pathways (FDR < 0.05), one linked to Epstein-Barr virus infection and another related to p53 signaling. For HIV/HCV-f vs. HIV-mono group, we found 44 SDE genes that revealed 31 enriched pathways (FDR < 0.05) related to inflammation, cancer/cell cycle alteration, viral and bacterial infection, and comorbidities associated with HIV/HCV-coinfection. Five genes were overrepresented in most pathways (JUN, NFKBIA, PIK3R2, CDC42, and STAT3).

Conclusion

HIV/HCV-coinfected patients who eradicated hepatitis C with IFN-based therapy showed profound gene expression changes after achieving sustained virological response. The altered pathways were related to inflammation and liver-related complications, such as non-alcoholic fatty liver disease and hepatocellular carcinoma, underscoring the need for active surveillance for these patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-021-00718-6.

The role of B-Cell Lymphoma-3 (BCL-3) in enabling the hallmarks of cancer: implications for the treatment of colorectal carcinogenesis

With its identification as a proto-oncogene in chronic lymphocytic leukaemia and central role in regulating NF-κB signalling, it is perhaps not surprising that there have been an increasing number of studies in recent years investigating the role of BCL-3 (B-Cell Chronic Lymphocytic Leukaemia/Lymphoma-3) in a wide range of human cancers. Importantly, this work has begun to shed light on our mechanistic understanding of the function of BCL-3 in tumour promotion and progression. Here, we summarize the current understanding of BCL-3 function in relation to the characteristics or traits associated with tumourigenesis, termed ‘Hallmarks of Cancer’. With the focus on colorectal cancer, a major cause of cancer related mortality in the UK, we describe the evidence that potentially explains why increased BCL-3 expression is associated with poor prognosis in colorectal cancer. As well as promoting tumour cell proliferation, survival, invasion and metastasis, a key emerging function of this proto-oncogene is the regulation of the tumour response to inflammation. We suggest that BCL-3 represents an exciting new route for targeting the Hallmarks of Cancer; in particular by limiting the impact of the enabling hallmarks of tumour promoting inflammation and cell plasticity. As BCL-3 has been reported to promote the stem-like potential of cancer cells, we suggest that targeting BCL-3 could increase the tumour response to conventional treatment, reduce the chance of relapse and hence improve the prognosis for cancer patients.

A pipeline to create predictive functional networks: application to the tumor progression of hepatocellular carcinoma

BACKGROUND

Integrating genome-wide gene expression patient profiles with regulatory knowledge is a challenging task because of the inherent heterogeneity, noise and incompleteness of biological data. From the computational side, several solvers for logic programs are able to perform extremely well in decision problems for combinatorial search domains. The challenge then is how to process the biological knowledge in order to feed these solvers to gain insights in a biological study. It requires formalizing the biological knowledge to give a precise interpretation of this information; currently, very few pathway databases offer this possibility.

RESULTS

The presented work proposes an automatic pipeline to extract automatically regulatory knowledge from pathway databases and generate novel computational predictions related to the state of expression or activity of biological molecules. We applied it in the context of hepatocellular carcinoma (HCC) progression, and evaluate the precision and the stability of these computational predictions. Our working base is a graph of 3383 nodes and 13,771 edges extracted from the KEGG database, in which we integrate 209 differentially expressed genes between low and high aggressive HCC across 294 patients. Our computational model predicts the shifts of expression of 146 initially non-observed biological components. Our predictions were validated at 88% using a larger experimental dataset and cross-validation techniques. In particular, we focus on the protein complexes predictions and show for the first time that NFKB1/BCL-3 complexes are activated in aggressive HCC. In spite of the large dimension of the reconstructed models, our analyses over the computational predictions discover a well constrained region where KEGG regulatory knowledge constrains gene expression of several biomolecules. These regions can offer interesting windows to perturb experimentally such complex systems.

CONCLUSION

This new pipeline allows biologists to develop their own predictive models based on a list of genes. It facilitates the identification of new regulatory biomolecules using knowledge graphs and predictive computational methods. Our workflow is implemented in an automatic python pipeline which is publicly available at https://github.com/LokmaneChebouba/key-pipeand contains as testing data all the data used in this paper.

Pre-S2 Start Codon Mutation of Hepatitis B Virus Subgenotype B3 Effects on NF-κB Expression and Activation in Huh7 Cell Lines

A cross-sectional study on hepatitis B patients in Indonesia showed association of pre-S2 start codon mutation (M120 V) with cirrhosis and hepatocellular carcinoma (HCC), which was dissimilar from studies from other populations where pre-S2 deletion mutation was more prevalent. Different mutation patterns were attributed to different hepatitis B virus (HBV) subgenotypes in each population study. HBV surface proteins are reported to induce the activation of NF-κB, a transcriptional factor known to play an important role in the development of liver disease. This study aimed to see the effects of HBs variants in HBV subgenotype B3 on the expression and activation of NF-κB as one of the mechanisms in inducing advanced liver disease. HBV subgenotypes B3, each carrying wild-type (wt) HBs, M120 V, and pre-S2 deletion mutation were isolated from three HCC patients. HBs genes were amplified and cloned into pcDNA3.1 and were transfected using Lipofectamine into a Huh7 cell line. NF-κB activation was measured through IκB-α expression, which is regulated by NF-κB. RNA expressions for HBs, IκB-α, and NF-κB subunit (p50) were evaluated using real-time PCR. M120 V mutant had a significantly higher mRNA level compared with wt and pre-S2 deletion mutant; however, there were no significant differences in HBs protein expressions. The transcription level of p50 was higher in M120 V mutation compared with HBs wild-type and pre-S2 deletion mutant. NF-κB activation was higher in HBs wild-type compared with the two mutant variants. Pre-S2 mutations had no effect on the increment of NF-κB activation. However, M120 V mutation may utilize a different pathway in liver disease progression that involves high expression of NF-κB subunit, p50.

Chemosensitization of HepG2 cells by suppression of NF-κB/p65 gene transcription with specific-siRNA

AIM

To investigate small interfering RNA (siRNA)-mediated inhibition of nuclear factor-kappa B (NF-κB) activation and multidrug-resistant (MDR) phenotype formation in human HepG2 cells.

METHODS

Total RNA was extracted from human HepG2 or LO2 cells. NF-κB/p65 mRNA was amplified by nested reverse transcription polymerase chain reaction and confirmed by sequencing. NF-κB/p65 was analyzed by immunohistochemistry. Specific-siRNA was transfected to HepG2 cells to knock down NF-κB/p65 expression. The effects on cell proliferation, survival, and apoptosis were assessed, and the level of NF-κB/p65 or P-glycoprotein (P-gp) was quantitatively analyzed by enzyme-linked immunosorbent assay.

RESULTS

HepG2 cells express NF-κB/p65 and express relatively less phosphorylated p65 (P-p65) and little P-gp. After treatment of HepG2 cells with different doses of doxorubicin, the expression of NF-κB/p65, P-p65, and especially P-gp were dose-dependently upregulated. After HepG2 cells were transfected with NF-κB/p65 siRNA (100 nmol/L), the expression of NF-κB/p65, P-p65, and P-gp were downregulated significantly and dose-dependently. The viability of HepG2 cells was decreased to 23% in the combination NF-κB/p65 siRNA (100 nmol/L) and doxorubicin (0.5 μmol/L) group and 47% in the doxorubicin (0.5 μmol/L) group (t = 7.043, P < 0.001).

CONCLUSION

Knockdown of NF-κB/p65 with siRNA is an effective strategy for inhibiting HepG2 cell growth by downregulating P-gp expression associated chemosensitization and apoptosis induction.

Hepatic B cell leukemia-3 suppresses chemically-induced hepatocarcinogenesis in mice through altered MAPK and NF-κB activation

The transcriptional nuclear factor kappa B (NF-κB)-coactivator B cell leukemia-3 (Bcl-3) is a molecular regulator of cell death and proliferation. Bcl-3 has been shown to be widely expressed in different cancer types including hepatocellular carcinoma (HCC). Its influence on hepatocarcinogenesis is still undetermined. To examine the role of Bcl-3 in hepatocarcinogenesis mice with hepatocyte-specific overexpression of Bcl-3 (Bcl-3^Hep) were exposed to diethylnitrosamine (DEN) and phenobarbital (PB). Hepatic Bcl-3 overexpression attenuated DEN/PB-induced hepatocarcinogenesis. Bcl-3^Hep mice exhibited a lower number and smaller tumor nodules in response to DEN/PB at 40 weeks of age. Reduced HCC formation was accompanied by a lower rate of cell proliferation and a distinct expression pattern of growth and differentiation-related genes. Activation of c-Jun N-terminal kinase (JNK) and especially extracellular-signal regulated kinase (ERK) was reduced in tumor and tumor-surrounding liver tissue of Bcl-3^Hep mice, while p38 and NF-κB p65 were phosphorylated to a higher extent compared to the wild type. In parallel, the absolute number of intrahepatic macrophages, CD8⁺ T cells and activated B cells was reduced in DEN/PB-treated Bcl-3^Hep mice mirroring a reduction of tumor-associated inflammation. Interestingly, at the early time point of 7 weeks following tumor initiation, a higher rate of apoptotic cell death was observed in Bcl-3^Hep mice. In summary, hepatocyte-restricted Bcl-3 overexpression reduced hepatocarcinogenesis related to prolonged liver injury early after tumor initiation likely due to decreased survival of DEN/PB-damaged, premalignant cells. Therefore, Bcl-3 could become a novel player in the development of therapeutic and diagnostic tools for HCC.

Identification of the transcriptional regulators by expression profiling infected with hepatitis B virus

BACKGROUND

The molecular pathogenesis of infection by hepatitis B virus with human is extremely complex and heterogeneous. To date the molecular information is not clearly defined despite intensive research efforts. Thus, studies aimed at transcription and regulation during virus infection or combined researches of those already known to be beneficial are needed.

AIMS

With the purpose of identifying the transcriptional regulators related to infection of hepatitis B virus in gene level, the gene expression profiles from some normal individuals and hepatitis B patients were analyzed in our study.

METHODS

In this work, the differential expressed genes were selected primarily. The several genes among those were validated in an independent set by qRT-PCR. Then the differentially co-expression analysis was conducted to identify differentially co-expressed links and differential co-expressed genes. Next, the analysis of the regulatory impact factors was performed through mapping the links and regulatory data. In order to give a further insight to these regulators, the co-expression gene modules were identified using a threshold-based hierarchical clustering method. Incidentally, the construction of the regulatory network was generated using the computer software.

RESULTS

A total of 137,284 differentially co-expressed links and 780 differential co-expressed genes were identified. These co-expressed genes were significantly enriched inflammatory response. The results of regulatory impact factors revealed several crucial regulators related to hepatocellular carcinoma and other high-rank regulators. Meanwhile, more than one hundred co-expression gene modules were identified using clustering method.

CONCLUSIONS

In our study, some important transcriptional regulators were identified using a computational method, which may enhance the understanding of disease mechanisms and lead to an improved treatment of hepatitis B. However, further experimental studies are required to confirm these findings.

Chemosensitization of HepG2 cells by suppression of NF-κB/p65 gene transcription with specific-siRNA

AIM

To investigate small interfering RNA (siRNA)-mediated inhibition of nuclear factor-kappa B (NF-κB) activation and multidrug-resistant (MDR) phenotype formation in human HepG2 cells.

METHODS

Total RNA was extracted from human HepG2 or LO2 cells. NF-κB/p65 mRNA was amplified by nested reverse transcription polymerase chain reaction and confirmed by sequencing. NF-κB/p65 was analyzed by immunohistochemistry. Specific-siRNA was transfected to HepG2 cells to knock down NF-κB/p65 expression. The effects on cell proliferation, survival, and apoptosis were assessed, and the level of NF-κB/p65 or P-glycoprotein (P-gp) was quantitatively analyzed by enzyme-linked immunosorbent assay.

RESULTS

HepG2 cells express NF-κB/p65 and express relatively less phosphorylated p65 (P-p65) and little P-gp. After treatment of HepG2 cells with different doses of doxorubicin, the expression of NF-κB/p65, P-p65, and especially P-gp were dose-dependently upregulated. After HepG2 cells were transfected with NF-κB/p65 siRNA (100 nmol/L), the expression of NF-κB/p65, P-p65, and P-gp were downregulated significantly and dose-dependently. The viability of HepG2 cells was decreased to 23% in the combination NF-κB/p65 siRNA (100 nmol/L) and doxorubicin (0.5 μmol/L) group and 47% in the doxorubicin (0.5 μmol/L) group (t = 7.043, P < 0.001).

CONCLUSION

Knockdown of NF-κB/p65 with siRNA is an effective strategy for inhibiting HepG2 cell growth by downregulating P-gp expression associated chemosensitization and apoptosis induction.

NF-κB-induced KIAA1199 promotes survival through EGFR signalling

Constitutive activation of EGFR- and NF-κB-dependent pathways is a hallmark of cancer, yet signalling proteins that connect both oncogenic cascades are poorly characterized. Here we define KIAA1199 as a BCL-3- and p65-dependent gene in transformed keratinocytes. KIAA1199 expression is enhanced on human papillomavirus (HPV) infection and is aberrantly expressed in clinical cases of cervical (pre)neoplastic lesions. Mechanistically, KIAA1199 binds Plexin A2 and protects from Semaphorin 3A-mediated cell death by promoting EGFR stability and signalling. Moreover, KIAA1199 is an EGFR-binding protein and KIAA1199 deficiency impairs EGF-dependent Src, MEK1 and ERK1/2 phosphorylations. Therefore, EGFR stability and signalling to downstream kinases requires KIAA1199. As such, KIAA1199 promotes EGF-mediated epithelial-mesenchymal transition (EMT). Taken together, our data define KIAA1199 as an oncogenic protein induced by HPV infection and constitutive NF-κB activity that transmits pro-survival and invasive signals through EGFR signalling.

Involvement of the NF-кB/p50/Bcl-3 complex in response to antiangiogenic therapy in a mouse model of metastatic renal cell carcinoma

Renal cell carcinoma (RCC) represents approximately 2-3% of human malignancies. Nuclear transcription factor кB (NF-кB) is composed of a family of transcription factors that have been associated with the development and progression of RCC. Endostatin (ES) is a fragment of collagen XVIII that possesses antiangiogenic activity. In this study, we evaluated the expression of NF-кB in metastatic tumor cells from animals treated with ES. Balb/c-bearing Renca-EGFP cells were treated with NIH/3T3-LendSN or NIH/3T3-LXSN cells as a control. At the end of the in vivo experiment, plasma Renca-EGFP-sorted cells and tissue lung samples were collected. A real-time PCR array for NF-κB target genes revealed that ES therapy led to down regulation of Bcl-3 (P<0.031), NF-кB1 (P<0.001) and c-Rel (P<0.004) in the ES-treated group. Using an electrophoretic mobility shift assay (EMSA), we observed a reduction in NF-kB binding activity in ES-treated Renca-EGP cells. Furthermore, a supershift assay showed a clear shift of the NF-кB DNA band in samples incubated with a p50 antibody. By immunohistochemistry analysis, ES treatment resulted in a significant reduction in expression of p50. (ES vs. control P<0.05). The immunoprecipitation experiments confirmed the presence of a p50/Bcl-3 complex in nuclear extracts from cells of metastatic lung tissues. Our findings indicate that p50 and Bcl-3 plays a regulatory role in gene transcription in RCC.

Hepatocellular carcinoma biology

Hepatocellular carcinoma (HCC) is the most common primary hepatic malignancy. Its incidence and prevalence is globally heterogeneous with the highest rates in Southeast Asia and Sub-Saharan Africa. In Western Industry nations, its incidence has significantly increased throughout the previous three decades. Its global heterogeneity is in part a reflection of the global distribution of its risk factors. Its prognosis is dismal with a 5-year survival of 11 %. The only potentially curative treatment is surgical with either resection or orthotopic liver transplantation. However, the majority of HCC patients are diagnosed at an advanced stage at which surgical therapies are not feasible. HCC is considered chemotherapy-resistant-a characteristic thought to be mediated in part through stem-like tumor initiating cells (STICs). Recent studies have provided significant insights in the hepatocarcinogenesis and the molecular signaling pathways of this malignancy resulting in the development of novel, molecular targeted therapies with modest therapeutic benefit. Our growing understanding of the biology of this malignancy will help in the development of novel, molecular-targeted therapies.

Transcriptional regulators in hepatocarcinogenesis--key integrators of malignant transformation

Hepatocellular carcinoma (HCC) is one of the most frequent human malignancies with poor prognosis and increasing incidence in the Western world. Only for a minority of HCC patients, surgical treatment options offer potential cure and therapeutic success of pharmacological approaches is limited. Highly specific approaches (e.g., kinase inhibitors) did not significantly improve the situation so far, possibly due to functional compensation, genetic heterogeneity of HCC, and development of resistance under selective pressure. In contrast, transcriptional regulators (especially transcription factors and co-factors) may integrate and process input signals of different (oncogenic) pathways and therefore represent cellular bottlenecks that regulate tumor cell biology. In this review, we want to summarize the current knowledge about central transcriptional regulators in human hepatocarcinogenesis and their potential as therapeutic target structures. Genomic and transcriptomic data of primary human HCC revealed that many of these factors showed up in subgroups of HCCs with a more aggressive phenotype, suggesting that aberrant activity of transcriptional regulators collect input information to promote tumor initiation and progression. Therefore, expression and dysfunction of transcription factors and co-factors may gain relevance for diagnostics and therapy of HCC.

Inflammation and cancer

There is evidence supporting the hypothesis that inflammation participates in providing conditions that lead to cancer. An unresolved inflammation due to any failure in the precise control of the immune response can continue to perturb the cellular microenvironment, thereby leading to alterations in cancer-related genes and posttranslational modification in crucial cellular proteins involved in the cell cycle, DNA repair and apoptosis. In addition, there are data indicating that inflammatory cells and immunomodulatory mediators present in the tumor microenvironment influence tumor progression and metastasis. Historically, tumor-infiltrating leukocytes have been considered to be manifestations of an intrinsic defence mechanism against developing tumors. However, increasing evidence indicates that leukocyte infiltration can promote tumor phenotypes, such as angiogenesis, growth and invasion. This may be due to inflammatory cells that probably can influence cancer promotion by secreting cytokines, growth factors, chemokines and proteases, which stimulate proliferation and invasiveness of cancer cells. Consequently, events and molecules implicated in this cross talk between the tumor microenvironment and inflammatory process may emerge as attractive targets in anticancer therapeutic interventions with significant clinical impact.

Clinicopathological significance of nuclear factor-κB activation in hepatocellular carcinoma

AIM

  Nuclear factor-κB (NF-κB) is a critical signaling mediator in inflammation, apoptosis resistance and oncogenesis. It has been reported that NF-κB is activated in several cancers, including hepatocellular carcinoma (HCC). Studies of genetic disruptions in mice also suggest that NF-κB plays critical roles in hepatocarcinogenesis. The aim of the present study is to characterize NF-κB activation and correlate it with the degree of malignancy in HCC.

METHODS

  To examine the correlation between the positivity of the nuclear p50 subunit and HCC recurrence, we analyzed immunostaining of the NF-κB p50 subunit in two groups of HCC samples with known prognosis and Akt phosphorylation status: 49 patients showing early recurrence within 6 months (group A) and 50 patients who were recurrence-free for at least for 3 years (group B).

RESULTS

  In group A, positive nuclear staining of p50 was shown in 18 cases (36.7%), whereas only one case (2.0%) in group B had positive nuclear staining of p50 (P = 2.48839 × 10(-5) ). This suggests a positive relationship between nuclear p50 and early recurrence and advanced HCC in humans. The presence of phosphorylated Akt correlated with nuclear staining of p50 in HCCs in group A (R(2)  = 0.213, P < 0.001).

CONCLUSION

  Our results indicate that nuclear staining of p50 was clearly associated with early recurrent HCC, and the Akt pathway might play a role in NF-κB activation in a subset of early recurrent HCC.

Cell death and hepatocarcinogenesis: Dysregulation of apoptosis signaling pathways

Hepatocellular carcinoma (HCC) remains a disease with a poor prognosis despite recent advances in the pathophysiology and treatment. Although the disease is biologically heterogeneous, dysregulation of cellular proliferation and apoptosis both occur frequently and contribute to the malignant phenotype. Chronic liver disease is associated with intrahepatic inflammation which promotes dysregulation of cellular signaling pathways; this triggers proliferation and thus lays the ground for expansion of premalignant cells. Cancer emerges when immunological control fails and transformed cells develop resistance against cell death signaling pathways. The same mechanisms underlie the poor responsiveness of HCC towards chemotherapy. Only recently advances in understanding the signaling pathways involved has led to the development of an effective pharmacological therapy for advanced disease. The current review will discuss apoptosis signaling pathways and focus on apoptosis resistance of HCC involving derangements in cell death receptors (e.g. tumor necrosis factor-alpha [TNF], CD95/Apo-1, TNF-related apoptosis-inducing ligand [TRAIL]) and associated adapter molecules (e.g. FADD and FLIP) of apoptotic signaling pathways. In addition, the role of the transcription factor nuclear factor-kappaB (NFκB) and members of the B cell leukemia-2 (Bcl-2) family that contribute to the regulation of apoptosis in hepatocytes are discussed. Eventually, the delineation of cell death signaling pathways could contribute to the implementation of new therapeutic strategies to treat HCC.

Suppression of human hepatoma (HepG2) cell growth by nuclear factor-kappaB/p65 specific siRNA

Nuclear factor-kappaB (NF-κB) is a transcription factor and antagonist of apoptosis during liver regeneration and closely related to the formation and development of hepatocellular carcinoma. In the present study, we investigated the effect of small interference RNA (siRNA)-mediated inhibition of NF-κB on growth of human hepatoma (HepG2) cells. Our data indicated that the expression of NF-κB/p65 mRNA was significantly higher in the HepG2 cells than that in the normal liver (LO2) cells before transfection, and the expression of NF-κB/p65 in the HepG2 cells with NF-κB/p65 siRNA (100 nMol/L) transfection at 72 h was reduced at the levels of mRNA (93%) and protein (62%) using real-time reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting. Interestingly, the apoptosis index of the HepG2 cells increased up to 85%, detected by Annexin V-fluorescein isothiocyanate, suggesting that NF-κB is overexpressed in hepatoma cells and can be inhibited by NF-κB/p65 siRNA through the apoptotic mechanism. Thus, we conclude that NF-κB is a potential molecular target for HCC gene therapy.

Suppression of human hepatoma (HepG2) cell growth by nuclear factor-kappaB/p65 specific siRNA

Nuclear factor-kappaB (NF-κB) is a transcription factor and antagonist of apoptosis during liver regeneration and closely related to the formation and development of hepatocellular carcinoma. In the present study, we investigated the effect of small interference RNA (siRNA)-mediated inhibition of NF-κB on growth of human hepatoma (HepG2) cells. Our data indicated that the expression of NF-κB/p65 mRNA was significantly higher in the HepG2 cells than that in the normal liver (LO2) cells before transfection, and the expression of NF-κB/p65 in the HepG2 cells with NF-κB/p65 siRNA (100 nMol/L) transfection at 72 h was reduced at the levels of mRNA (93%) and protein (62%) using real-time reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting. Interestingly, the apoptosis index of the HepG2 cells increased up to 85%, detected by Annexin V-fluorescein isothiocyanate, suggesting that NF-κB is overexpressed in hepatoma cells and can be inhibited by NF-κB/p65 siRNA through the apoptotic mechanism. Thus, we conclude that NF-κB is a potential molecular target for HCC gene therapy.

Nuclear factor κ-light chain-enhancer of activated B cells is activated by radiotherapy and is prognostic for overall survival in patients with rectal cancer treated with preoperative fluorouracil-based chemoradiotheraphy

PURPOSE

Rectal cancer is often clinically resistant to radiotherapy (RT) and identifying molecular markers to define the biologic basis for this phenomenon would be valuable. The nuclear factor κ-light chain-enhancer of activated B cells (NF-κB) is a potential anti-apoptotic transcription factor that has been associated with resistance to RT in model systems. The present study was designed to evaluate NF-κB activation in patients with rectal cancer undergoing chemoradiotherapy to determine whether NF-κB activity correlates with the outcome in rectal cancer patients.

METHODS AND MATERIALS

A total of 22 patients underwent biopsy at multiple points in a prospective study and the data from another 50 were analyzed retrospectively. The pretreatment tumor tissue was analyzed for multiple NF-κB subunits by immunohistochemistry. Serial tumor biopsy cores were analyzed for NF-κB-regulated gene expression using reverse transcriptase polymerase chain reaction and for NF-κB subunit nuclear localization using immunohistochemistry.

RESULTS

Several NF-κB target genes (Bcl-2, cellular inhibitor of apoptosis protein [cIAP]2, interleukin-8, and tumor necrosis factor receptor-associated-1) were significantly upregulated by a single fraction of RT at 24 h, demonstrating for the first time that NF-κB is activated by RT in human rectal tumors. The baseline NF-κB p50 nuclear expression did not correlate with the pathologic response to RT. However, an increasing baseline p50 level was prognostic for overall survival (hazard ratio, 2.15; p = .040).

CONCLUSION

NF-κB nuclear expression at baseline in rectal cancer was prognostic for overall survival but not predictive of the response to RT. Larger patient numbers are needed to assess the effect of NF-κB target gene upregulation on the response to RT. Our results suggest that NF-κB might play an important role in tumor metastasis but not to the resistance to chemoradiotherapy.

BCL-3 degradation involves its polyubiquitination through a FBW7-independent pathway and its binding to the proteasome subunit PSMB1

The oncogenic protein BCL-3 activates or represses gene transcription through binding with the NF-kappaB proteins p50 and p52 and is degraded through a phospho- and GSK3-dependent pathway. However, the mechanisms underlying its degradation remain poorly understood. Yeast two-hybrid analysis led to the identification of the proteasome subunit PSMB1 as a BCL-3-associated protein. The binding of BCL-3 to PSMB1 is required for its degradation through the proteasome. Indeed, PSMB1-depleted cells are defective in degrading polyubiquitinated BCL-3. The N-terminal part of BCL-3 includes lysines 13 and 26 required for the Lys(48)-linked polyubiquitination of BCL-3. Moreover, the E3 ligase FBW7, known to polyubiquitinate a variety of substrates phosphorylated by GSK3, is dispensable for BCL-3 degradation. Thus, our data defined a unique motif of BCL-3 that is needed for its recruitment to the proteasome and identified PSMB1 as a key protein required for the proteasome-mediated degradation of a nuclear and oncogenic IkappaB protein.

The repressing function of the oncoprotein BCL-3 requires CtBP, while its polyubiquitination and degradation involve the E3 ligase TBLR1

The nuclear and oncogenic BCL-3 protein activates or represses gene transcription when bound to NF-kappaB proteins p50 and p52, yet the molecules that specifically interact with BCL-3 and drive BCL-3-mediated effects on gene expression remain largely uncharacterized. Moreover, GSK3-mediated phosphorylation of BCL-3 triggers its degradation through the proteasome, but the proteins involved in this degradative pathway are poorly characterized. Biochemical purification of interacting partners of BCL-3 led to the identification of CtBP as a molecule required for the ability of BCL-3 to repress gene transcription. CtBP is also required for the oncogenic potential of BCL-3 and for its ability to inhibit UV-mediated cell apoptosis in keratinocytes. We also defined the E3 ligase TBLR1 as a protein involved in BCL-3 degradation through a GSK3-independent pathway. Thus, our data demonstrate that the LSD1/CtBP complex is required for the repressing abilities of an oncogenic I kappaB protein, and they establish a functional link between the E3 ligase TBLR1 and NF-kappaB.

NF-kB and Bcl-3 activation are prognostic in metastatic colorectal cancer

PURPOSE

NF-kappaB is an antiapoptotic transcription factor that has been shown to be a mediator of treatment resistance. Bcl-3 is a regulator of NF-kappaB that may play a role in oncogenesis. The goal of this study was to correlate the activation status of NF-kappaB and Bcl-3 with clinical outcome in a group of patients with metastatic colorectal cancer (CRC).

METHODS

A retrospective study of 23 patients who underwent surgical resection of CRC at the University of North Carolina (UNC). Activation of NF-kappaB was defined by nuclear expression of select components of NF-kappaB (p50, p52, p65) and Bcl-3. Tissue microarrays were created from cores of normal mucosa, primary tumor, lymph node metastases and liver metastases in triplicate from disparate areas of the blocks, and an intensity score was generated by multiplying intensity (0-3+) by percent of positive tumor cells. Generalized estimating equations were used to note differences in intensity scores among normal mucosa and nonnormal tissues. Cox regression models were fit to see if scores were significantly associated with overall survival.

RESULTS

p65 NE was significantly higher in primary tumor and liver metastases than normal mucosa (both p < 0.01). p50 nuclear expression was significantly higher for all tumor sites than for normal mucosa (primary tumor and lymph node metastases p < 0.0001, liver metastases p < 0.01). Bcl-3 nuclear expression did not differ significantly between normal mucosa and tumor; however, nuclear expression in primary tumor for each of these components was strongly associated with survival: the increase in hazard for each 50-point increase in nuclear expression was 91% for Bcl-3, 66% for p65, and 52% for p50 (all p < 0.05).

CONCLUSIONS

Activation of canonical NF-kappaB subunits p50 and p65 as measured by nuclear expression is strongly associated with survival suggesting NF-kappaB as a prognostic factor in this disease. Primary tumor nuclear expression appears to be as good as, or better than, metastatic sites at predicting prognosis. Bcl-3 nuclear expression is also negatively associated with survival and deserves further study in CRC.

Role of nuclear factor kappaB in liver health and disease

NF-kappaB (nuclear factor kappaB) is a heterodimeric transcription factor that is constitutively expressed in all cell types and has a central role as a transcriptional regulator in response to cellular stress. In the present review, we discuss the role of NF-kappaB signalling in the maintenance of liver homoeostasis as well as in the pathogenesis of a wide variety of conditions affecting the liver, including viral hepatitis, steatohepatitis, cirrhosis and hepatocellular carcinoma. Much of the current knowledge of NF-kappaB signalling in the liver relates to the canonical pathway, the IKK [IkappaB (inhibitor of kappaB) kinase] complex and the RelA subunit. We explore the weaknesses of the experimental approaches to date and suggest that further work is needed to investigate in detail the discreet functions of each of the Rel subunits in liver physiology and disease.

NF-kappaB signalling: embracing complexity to achieve translation

NF-kappaB is a dimeric transcription factor that has emerged as an important regulator of liver homeostasis and is mechanistically implicated in a variety of liver pathologies including hepatitis, steatosis, fibrosis, and hepatocellular carcinoma. The question remains as to whether NF-kappaB can really be exploited for the development of therapeutics for these pathologies in the diseased human liver. This review casts a critical eye on the experimental evidence gathered to date and in particular questions the rationale for the current focus on components of the upstream IKK complex as therapeutic targets. We make the argument that translation of NF-kappaB biology to new therapies is more likely to emerge from a re-focus of basic research back to the NF-kappaB/Rel subunit functions and the complexities of their post-translational modifications and context-dependent co-regulator interactions.

NF-κB in liver cancer: the plot thickens

The role of the NF-κB signaling pathway in liver cancer is complex. While some evidence suggests that in the liver, like in many other organ systems, NF-κB is oncogenic, there is strong evidence showing that in certain liver cancer models NF-κB suppresses tumorigenesis. These contrasting findings cannot be dismissed on technicalities and are likely due to the complex nature of the NF-κB response. Similar contrasting findings regarding NF-κB activity are revealed in skin cancer models. Thus, it is possible that the contradictory role of NF-κB in tumorigenesis is a general phenomenon and not an oddity related solely to the liver. Further studies are indicated to decipher the underlying molecular mechanisms. Revealing these mechanisms may facilitate the identification of patient subgroups and specific situations in which NF-κB inhibition will be a preferred therapeutic option. Moreover, it is possible that specific interventions could boost the tumor suppressor functions of NF-κB in tumors that harbor mutations that render this pathway constitutively active.

The biological functions of NF-kappaB1 (p50) and its potential as an anti-cancer target

Nuclear factor-kappaB (NF-kappaB) is a key transcriptional factor family that consists of five members in mammalian cells, including NF-kappaB1 (p50), NF-kappaB2 (p52), RelA (p65), RelB and c-Rel. NF-kappaB is implicated in multiple physiological and pathological processes, including cell proliferation and differentiation, inflammatory and immune response, cell survival and apoptosis, cellular stress reactions and tumorigenesis. Recent studies by our group and others have highlighted the novel functions of the p50 protein. In this review, we will focus on the regulation and functions of NF-kappaB p50.

Inflammation and cancer: how friendly is the relationship for cancer patients?

Evidence has emerged in the last two decades that at the molecular level most chronic diseases, including cancer, are caused by a dysregulated inflammatory response. The identification of transcription factors such as NF-kappaB, AP-1 and STAT3 and their gene products such as tumor necrosis factor, interleukin-1, interleukin-6, chemokines, cyclooxygenase-2, 5 lipooxygenase, matrix metalloproteases, and vascular endothelial growth factor, adhesion molecules and others have provided the molecular basis for the role of inflammation in cancer. These inflammatory pathways are activated by tobacco, stress, dietary agents, obesity, alcohol, infectious agents, irradiation, and environmental stimuli, which together account for as much as 95% of all cancers. These pathways have been implicated in transformation, survival, proliferation, invasion, angiogenesis, metastasis, chemoresistance, and radioresistance of cancer, so much so that survival and proliferation of most types of cancer stem cells themselves appear to be dependent on the activation of these inflammatory pathways. Most of this evidence, however, is from preclinical studies. Whether these pathways have any role in prevention, progression, diagnosis, prognosis, recurrence or treatment of cancer in patients, is the topic of discussion of this review. We present evidence that inhibitors of inflammatory biomarkers may have a role in both prevention and treatment of cancer.

The proto-oncogene Bcl3, induced by Tax, represses Tax-mediated transcription via p300 displacement from the human T-cell leukemia virus type 1 promoter

The etiology of human T-cell leukemia virus type 1 (HTLV-1)-induced adult T-cell leukemia is linked to the expression of the viral oncoprotein Tax. Although the mechanism of retroviral transformation is unknown, Tax interferes with fundamental cellular processes, including proliferation and apoptosis, and these events may directly link Tax to early steps in malignant progression. In this study, we examined the interplay between Tax and the potent proto-oncogene B-cell chronic leukemia protein 3 (Bcl3). Bcl3 is a critical regulator of cell survival and proliferation and is overexpressed in HTLV-1-infected cells. We found that Tax induced Bcl3 expression through stimulation of the NF-kappaB pathway. An intronic NF-kappaB binding site within the Bcl3 gene served as the primary target of Tax-induced NF-kappaB activation. We next considered the consequence of Bcl3 overexpression on Tax function. Interestingly, we found that Bcl3 formed a stable complex with Tax and that this complex potently inhibited Tax-dependent HTLV-1 transcription. Importantly, Bcl3 associated with the HTLV-1 promoter in a Tax-dependent manner and inhibited the binding of the critical cellular coactivator p300. The conserved ankyrin repeat domain of Bcl3 mediated both Tax binding and inhibition of p300 recruitment to the HTLV-1 promoter. Together, these data suggest that Tax-induced Bcl3 overexpression benefits the virus in two important ways. First, Bcl3 may promote cell division and thus clonal proliferation of the virus. Second, Bcl3 may attenuate virion production, facilitating immune evasion. One consequence of this regulatory loop may be Bcl3-induced malignant transformation of the host cell.