Over-expression of nuclear NF-κB1 and c-Rel correlates with chemoresistance and prognosis of serous epithelial ovarian cancer

Transcription factor A, mitochondrial promotes lymph node metastasis and lymphangiogenesis in epithelial ovarian carcinoma

Background

Mitochondria play a central, multifunctional role in cancer progression. However, the mechanism of mitochondrial genes in epithelial ovarian cancer (EOC) remains unclear. This study aimed to screen candidate mitochondrial genes in EOC and then to investigate their biological functions and potential mechanisms.

Methods

We downloaded Gene Expression Omnibus RNA-seq profiles and identified mitochondrial differentially expressed genes in EOC by bioinformatics analysis. Transcription factor A, mitochondrial (TFAM) expression in EOC tissues was determined by immunohistochemistry. In vitro assays were applied to clarify TFAM function in EOC.

Results

The bioinformatics analysis results showed that the mitochondrial genes TFAM, HSPE1, and CYC1 were significantly upregulated (P < 0.05) in EOC, and their upregulation was associated with a poor prognosis. TFAM was highly expressed in EOC tissues and significantly associated with clinical stage (P = 0.004), lymph node metastasis (P = 0.043), and overall survival (P < 0.05). Silencing TFAM in EOC cells significantly inhibited cell proliferation and migration and induced cell apoptosis (P < 0.05).

Conclusion

TFAM promotes EOC cell secretion of VEGF-A, VEGF-C, VEGF-D, lymphangiogenesis, and EOC lymph node metastasis. Our results may provide new insights into the biological functions and potential mechanisms of TFAM in EOC, which might provide new targets for EOC diagnosis and treatment.

KDM1A/LSD1 inhibition enhances chemotherapy response in ovarian cancer

Ovarian cancer (OCa) is the deadliest of all gynecological cancers. The standard treatment for OCa is platinum-based chemotherapy, such as carboplatin or cisplatin in combination with paclitaxel. Most patients are initially responsive to these treatments; however, nearly 90% will develop recurrence and inevitably succumb to chemotherapy-resistant disease. Recent studies have revealed that the epigenetic modifier lysine-specific histone demethylase 1A (KDM1A/LSD1) is highly overexpressed in OCa. However, the role of KDM1A in chemoresistance and whether its inhibition enhances chemotherapy response in OCa remains uncertain. Analysis of TCGA datasets revealed that KDM1A expression is high in patients who poorly respond to chemotherapy. Western blot analysis show that treatment with chemotherapy drugs cisplatin, carboplatin, and paclitaxel increased KDM1A expression in OCa cells. KDM1A knockdown (KD) or treatment with KDM1A inhibitors NCD38 and SP2509 sensitized established and patient-derived OCa cells to chemotherapy drugs in reducing cell viability and clonogenic survival and inducing apoptosis. Moreover, knockdown of KDM1A sensitized carboplatin-resistant A2780-CP70 cells to carboplatin treatment and paclitaxel-resistant SKOV3-TR cells to paclitaxel. RNA-seq analysis revealed that a combination of KDM1A-KD and cisplatin treatment resulted in the downregulation of genes related to epithelial-mesenchymal transition (EMT). Interestingly, cisplatin treatment increased a subset of NF-κB pathway genes, and KDM1A-KD or KDM1A inhibition reversed this effect. Importantly, KDM1A-KD, in combination with cisplatin, significantly reduced tumor growth compared to a single treatment in an orthotopic intrabursal OCa xenograft model. Collectively, these findings suggest that combination of KDM1A inhibitors with chemotherapy could be a promising therapeutic approach for the treatment of OCa.

"DEPHENCE" system-a novel regimen of therapy that is urgently needed in the high-grade serous ovarian cancer-a focus on anti-cancer stem cell and anti-tumor microenvironment targeted therapies

Ovarian cancer, especially high-grade serous type, is the most lethal gynecological malignancy. The lack of screening programs and the scarcity of symptomatology result in the late diagnosis in about 75% of affected women. Despite very demanding and aggressive surgical treatment, multiple-line chemotherapy regimens and both approved and clinically tested targeted therapies, the overall survival of patients is still unsatisfactory and disappointing. Research studies have recently brought some more understanding of the molecular diversity of the ovarian cancer, its unique intraperitoneal biology, the role of cancer stem cells, and the complexity of tumor microenvironment. There is a growing body of evidence that individualization of the treatment adjusted to the molecular and biochemical signature of the tumor as well as to the medical status of the patient should replace or supplement the foregoing therapy. In this review, we have proposed the principles of the novel regimen of the therapy that we called the "DEPHENCE" system, and we have extensively discussed the results of the studies focused on the ovarian cancer stem cells, other components of cancer metastatic niche, and, finally, clinical trials targeting these two environments. Through this, we have tried to present the evolving landscape of treatment options and put flesh on the experimental approach to attack the high-grade serous ovarian cancer multidirectionally, corresponding to the "DEPHENCE" system postulates.

Potential effects of fructus aurantii ethanol extracts against colitis-associated carcinogenesis through coordination of Notch/NF-κB/IL-1 signaling pathways

Colitis-associated cancer (CAC) is the colorectal cancer (CRC) subtype that is difficult to treat, and shows high mortality. The consumption of flavonoid-rich fructus aurantii extracts (FAE) has been associated with multiple beneficial effects including anti-inflammatory and anti-cancer properties, but the potential effects on the colitis-associated carcinogenesis have not been thoroughly investigated. Recent clinical data show that, as yet, few agents clearly inhibited CRC development in long-standing inflammatory bowel diseases. Here, we identified that FAE showed significant efficiency to inhibit HT-29 cell proliferation. The potential of FAE in vivo was further evaluated in an AOM/DSS-induced CAC mouse model. Intriguingly, FAE diminished the number of polyps in mice. Furthermore, FAE inhibited CAC by regulating the gene expression of Notch/ NF-κB/IL-1 signaling pathways. Collectively, these results were indicative of FAE has great potential in CAC prevention and treatment.

Interaction Analysis of MRP1 with Anticancer Drugs Used in Ovarian Cancer: In Silico Approach

Multidrug resistance (MDR) is one of the major therapeutic challenges that limits the efficacy of chemotherapeutic response resulting in poor prognosis of ovarian cancer (OC). The multidrug resistance protein 1 (MRP1) is a membrane-bound ABC transporter involved in cross resistance to many structurally and functionally diverse classes of anticancer drugs including doxorubicin, taxane, and platinum. In this study, we utilize homology modelling and molecular docking analysis to determine the binding affinity and the potential interaction sites of MRP1 with Carboplatin, Gemcitabine, Doxorubicin, Paclitaxel, and Topotecan. We used AutoDock Vina scores to compare the binding affinities of the anticancer drugs against MRP1. Our results depicted Carboplatin < Gemcitabine < Topotecan < Doxorubicin < Paclitaxel as the order of binding affinities. Paclitaxel has shown the highest binding affinity whereas Carboplatin displayed the lowest affinity to MRP1. Interestingly, our data showed that Carboplatin, Paclitaxel, and Topotecan bind specifically to Asn510 residue in the transmembrane domains 1 of the MRP1. Our results suggest that Carboplatin could be an appropriate therapeutic choice against MRP1 in OC as it couples weakly with Carboplatin. Further, our findings also recommend opting Carboplatin with Gemcitabine as a combinatorial chemotherapeutic approach to overcome MDR phenotype associated with recurrent OC.

Platelets, Thrombocytosis, and Ovarian Cancer Prognosis: Surveying the Landscape of the Literature

Platelets are critical components of a number of physiologic processes, including tissue remodeling after injury, wound healing, and maintenance of vascular integrity. Increasing evidence suggests that platelets may also play important roles in cancer. In ovarian cancer, thrombocytosis, both at the time of initial diagnosis and at recurrence, has been associated with poorer prognosis. This review describes current evidence for associations between thrombocytosis and ovarian cancer prognosis and discusses the clinical relevance of platelet count thresholds and timing of assessment. In addition, we discuss several mechanisms from in vitro, in vivo, and clinical studies that may underlie these associations and recommend potential approaches for novel therapeutic targets for this lethal disease.

High Expression of Nuclear Transcription Factor-κB is Associated with Cisplatin Resistance and Prognosis for Ovarian Cancer

Background

Abnormal activation of the nuclear transcription factor-κB (NF-κB) signaling pathway plays a crucial role in the chemoresistance of tumor cells. This study aimed to explore the significance of NF-κB in the chemoresistance of ovarian cancer.

Materials

We performed immunohistochemical staining for evaluating the expression of NF-κB in cancer tissues. The MTT assay was performed for analyzing cell proliferation, Western blotting was performed to quantify NF-κB p65, and flow cytometry was used to determine the apoptosis rate.

Results

Nuclear NF-κB p65 over-expression was closely associated with ovarian cancer with advanced FIGO stage, residual disease ≥1 cm, low histologic grade, platinum resistance and refractory, chemotherapy resistance (P< 0.05). FIGO stage I–II and residual disease <1 cm were associated with complete response (CR) to chemotherapy, while FIGO stage I–II, residual disease <1cm and absence of lymph node (LN) metastasis were associated with platinum sensitivity. In multivariate logistic regression, residual disease ≥1 cm was a risk factor for response to chemotherapy, while the over-expression of nuclear NF-κB p65 was a risk factor for sensitivity to chemotherapy. In the ROC curves, nuclear NF-κB p65 expression had the discriminative ability for sensitivity to chemotherapy (AUC = 0.637, P = 0.021). Furthermore, nuclear NF-κB p65 expression was an independent prognostic factor. Western blotting showed that NF-κB p65 level in cisplatin-resistant cells (C13* and A2780cp) was significantly higher than that in cisplatin-sensitive cells (OV2008 and A2780s) (P < 0.05), and this increased expression could be suppressed by NF-κB inhibitor-PDTC treatment. The proliferation inhibitory rates of cisplatin in C13* and A2780cp cells increased after PDTC treatment in a concentration-dependent manner. PDTC treatment could also enhance cisplatin-induced apoptosis.

Conclusion

NF-κB was associated with the clinicopathological features, chemoresistance, and prognosis of ovarian cancer. The NF-κB inhibitor PDTC can enhance cisplatin sensitivity of platinum-resistant C13* and A2780cp ovarian cancer cells.

Expression of p52, a non-canonical NF-kappaB transcription factor, is associated with poor ovarian cancer prognosis

BACKGROUND

The canonical and non-canonical nuclear factor-kappaB (NF-κB) signaling pathways have key roles in cancer, but studies have previously evaluated only the association of canonical transcription factors and ovarian cancer survival. Although a number of in vitro and in vivo studies have demonstrated mechanisms by which non-canonical NF-κB signaling potentially contributes to ovarian cancer progression, a prognostic association has yet to be shown in the clinical context.

METHODS

We assayed p65 and p52 (major components of the canonical and non-canonical NF-κB pathways) by immunohistochemistry in epithelial ovarian tumor samples; nuclear and cytoplasmic staining were semi-quantified by H-scores and dichotomized at median values. Associations of p65 and p52 with progression-free survival (PFS) and overall survival (OS) were quantified by Hazard Ratios (HR) from proportional-hazards regression.

RESULTS

Among 196 cases, median p52 and p65 H-scores were higher in high-grade serous cancers. Multivariable regression models indicated that higher p52 was associated with higher hazards of disease progression (cytoplasmic HR: 1.54; nuclear HR: 1.67) and death (cytoplasmic HR: 1.53; nuclear HR: 1.49), while higher nuclear p65 was associated with only a higher hazard of disease progression (HR: 1.40) in unadjusted models. When cytoplasmic and nuclear staining were combined, p52 remained significantly associated with increased hazards of disease progression (HR: 1.91, p = 0.004) and death (HR: 1.70, p = 0.021), even after adjustment for p65 and in analyses among only high-grade serous tumors.

CONCLUSIONS

This is the first study to demonstrate that p52, a major component of non-canonical NF-κB signaling, may be an independent prognostic factor for epithelial ovarian cancer, particularly high-grade serous ovarian cancer. Approaches to inhibit non-canonical NF-κB signaling should be explored as novel ovarian cancer therapies are needed.

MDR1 Gene Polymorphisms and Its Association With Expression as a Clinical Relevance in Terms of Response to Chemotherapy and Prognosis in Ovarian Cancer

In spite of the significant advancements in the treatment modalities, 30% of advanced stage ovarian cancer (OC) patients do not respond to the standard chemotherapeutic regimen and most of the responders finally relapse over time due to the escalation of multidrug resistance (MDR) Phenomenon. Our present study evaluated chemotherapeutic sensitivity response among 47 ovarian tumor patients of which we found 37 (78.8%) sensitive and remaining 10 (21.2%) resistant. Among the resistant, seven tumor samples were found to be platinum resistant or refractory to platinum (CB/TX), one to carboplatin, and two to 5FU. Notably, all these resistant cases were observed in the disease recurrence group of patients identified at stage III or IV. The stage III resistant cases revealed heterozygous mutation (C/T) in exon 12 (C1236T) and 26 (C3435T) and increased level of mRNA, whereas homozygous mutation (T/T) was found at stage IV tumor patients. The genotypic difference was found to be significant (p = 0.03) for exon 12, and p = 0.003 for exon 26 mutant genotypes. No significant association between genotypes of different exons with tumor stages and tumor grade was observed (p > 0.05). However, a significant association was observed between the genotype of exon-12 and histopathology of tumor tissue (p = 0.028). Statistically, the chemotherapy response was found to be significantly associated with the tumor stage (p = 0.019). We also observed a significant difference in PFS (P = 0.019) and OS (P = 0.047) between tumor grades 1 and 3. Notably, the highest mRNA expression was observed in resistant tumor sample T-32, where interestingly we found homozygosity TT in all of the exons 12, 21, and 26. Thus, we suggest that exons 12 (C1236T) and exon 26 (C3435T) polymorphism may play a role in inducing drug resistance by altering the expression level of the MDR1 gene. To summarize, we suggest that the expression of MDR1 in OC is influenced by tumor stage and genotype variants as well as by chemotherapeutic drugs. Thus our findings suggest that inter individual variability in platinum based therapy may be anticipated by MDR1 genotypes. Further studies on a large number of samples shall eventually lead to provide beneficial information for the individualized chemotherapy.

Systematic Identification of Characteristic Genes of Ovarian Clear Cell Carcinoma Compared with High-Grade Serous Carcinoma Based on RNA-Sequencing

Objective: Ovarian cancer has the highest mortality among gynecological cancers. High-grade serous carcinoma (HGSC) is the most common histotype of ovarian cancer regardless of ethnicity, whereas clear cell carcinoma (CCC) is more common in East Asians than Caucasians. The elucidation of predominant signaling pathways in these cancers is the first step towards understanding their molecular mechanisms and developing their clinical management. Methods: RNA sequencing was performed for 27 clinical ovarian specimens from Japanese women. Principal component analysis (PCA) was conducted on the sequence data mapped on RefSeq with normalized read counts, and functional annotation analysis was performed on genes with substantial weights in PCA. Knockdown experiments were conducted on the selected genes on the basis of PCA. Results: Functional annotation analysis of PCA-defined genes showed predominant pathways, such as cell growth regulators and blood coagulators in CCC and transcription regulators in HGSC. Knockdown experiments showed that the inhibition of the calcium-dependent protein copine 8 (CPNE8) and the transcription factor basic helix-loop-helix family member e 41 (BHLHE41) repressed the proliferation of CCC- and HGSC-derived cells, respectively. Conclusions: This study identified CPNE8 and BHLHE41 as characteristic genes for CCC and HGSC, respectively. The systemic identification of differentially expressed genes in CCC and HGSC will provide useful information to understand transcriptomic differences in these ovarian cancers and to further develop potential diagnostic and therapeutic options for advanced disease.

NF-κB Signaling in Ovarian Cancer

The NF-κB signaling pathway is a master and commander in ovarian cancer (OC) that promotes chemoresistance, cancer stem cell maintenance, metastasis and immune evasion. Many signaling pathways are dysregulated in OC and can activate NF-κB signaling through canonical or non-canonical pathways which have both overlapping and distinct roles in tumor progression. The activation of canonical NF-κB signaling has been well established for anti-apoptotic and immunomodulatory functions in response to the tumor microenvironment and the non-canonical pathway in cancer stem cell maintenance and tumor re-initiation. NF-κB activity in OC cells helps to create an immune-evasive environment and to attract infiltrating immune cells with tumor-promoting phenotypes, which in turn, drive constitutive NF-κB activation in OC cells to promote cell survival and metastasis. For these reasons, NF-κB is an attractive target in OC, but current strategies are limited and broad inhibition of this major signaling pathway in normal physiological and immunological functions may produce unwanted side effects. There are some promising pre-clinical outcomes from developing research to target and inhibit NF-κB only in the tumor-reinitiating cancer cell population of OC and concurrently activate canonical NF-κB signaling in immune cells to promote anti-tumor immunity.

Intersection of the p63 and NF-κB pathways in epithelial homeostasis and disease

Overexpression of ΔNp63α, a member of the p53/p63/p73 family of transcription factors, is a molecular attribute of human squamous cancers of the head and neck, lung and skin. The TP63 gene plays important roles in epidermal morphogenesis and homeostasis, regulating diverse biological processes including epidermal fate decisions and keratinocyte proliferation and survival. When overexpressed experimentally in primary mouse keratinocytes, ΔNp63α maintains a basal cell phenotype including the loss of normal calcium-mediated growth arrest, at least in part through the activation and enhanced nuclear accumulation of the c-rel subunit of NF-κB (Nuclear Factor-kappa B). Initially identified for its role in the immune system and hematopoietic cancers, c-Rel has increasingly been associated with solid tumors and other pathologies. ΔNp63α and c-Rel have been shown to be associated in the nuclei of ΔNp63α overexpressing human squamous carcinoma cells. Together, these transcription factors cooperate in the transcription of genes regulating intrinsic keratinocyte functions, as well as the elaboration of factors that influence the tumor microenvironment (TME). This review provides an overview of the roles of ΔNp63α and c-Rel in normal epidermal homeostasis and elaborates on how these pathways may intersect in pathological conditions such as cancer and the associated TME.

Evodiamine inactivates NF-κB and potentiates the antitumor effects of gemcitabine on tongue cancer both in vitro and in vivo

Objective

The aim of this study was to investigate whether evodiamine (EVO) could potentiate the antitumor activity of gemcitabine (GEM) in tongue cancer cells and determine its potential underlying mechanisms.

Materials and methods

Human Tca8113 and CAL-27 tongue squamous carcinoma cell lines were treated with EVO and GEM in different sequences and doses, after which cell proliferation was measured. Drug interactions were analyzed using the Chou–Talalay method with CompuSyn software. Clonality, apoptosis, and migration were measured using the plate clone formation assay, annexin V/propidium iodide (PI) staining, Hoechst 33342 staining, and the wound-healing test. The activity of the nuclear factor kappa light-chain enhancer of activated B cell (NF-κB) p65 subunit and its downstream proteins was quantified by Western blotting. The effects of the drug combination in vivo were assessed using a CAL-27 heterotopic xenograft model.

Results

EVO and GEM had synergistic effects on CAL-27 and Tca8113 cell lines in time- and concentration-dependent manners. Combination of drugs inhibited cell proliferation and migration and reduced the expression of NF-κB p65, B cell lymphoma 2 (Bcl-2), and B cell lymphoma extra large (Bcl-xl) compared with the control and either drug alone. In vivo, combination treatment of the xenograft model with EVO and GEM led to a significant reduction in tumor volume growth and inhibited the activation of NF-κB p65 with no obvious adverse reactions.

Conclusion

The results of this study showed that EVO may inhibit cancer cells by suppressing NF-κB activity, and in combination with GEM, it may increase the chemosensitivity of tongue squamous cancer cells, thereby improving the treatment response.

Immunhistochemical analysis of Nuclear Factor Kappa Beta expression in etiopathogenesis of ovarian tumors1

PURPOSE

To investigate the place of the transcription factor nuclear kappa B (NF-kB), which is a marker of chronic inflammation, in the etiology of the ovarian carcinoma.

METHODS

NFkB analysis with the immunohistochemical method has been performed. To evaluate immunohistochemical NF-kB expression in the ovarian tissue, the H-score method. H-score = ∑ Pi (i+1), where ''Pi'' is the percentage of stained cells in each intensity category (0-100%) and ''i'' is the intensity indicating weak (i=1), moderate (i=2) or strong staining (i=3).

RESULTS

It has been seen that, the mean H score is statistically significantly higher in the patient group with serous and musinous adenocarcinoma diagnosis than the two other patient groups (p<0.005).

CONCLUSIONS

Factor nuclear kappa B is an important mediator that acts in the chronic inflammation. The highest expression rates are determined by the immunohistochemical method in the ovarian cancer group.

Prognostic value of GRIM-19, NF-κB and IKK2 in patients with high-grade serous ovarian cancer

AIMS

High grade serous carcinoma (HGSC) is an aggressive tumour, and most patients relapse after treatment, acquiring resistance to platinum-based chemotherapy. One of the resistance mechanisms proposed is apoptosis evasion triggered by drug-related cytotoxic effect in the cell. In this context, this study aims to evaluate the protein expression of GRIM-19, NF-κB and IKK2, their association with chemotherapy response and to determine their prognostic values in HGSC.

METHODS

GRIM-19, NF-κB and IKK2 expression was evaluated by immunohistochemistry (IHC) in 71 patients with HGSC selected between 2003 and 2013, whose underwent primary debulking surgery with complete cytoreduction. Protein expression was analyzed in relation to platinum response groups, tumour progression, clinicopathological data and survival.

RESULTS

Positive IKK2 expression was related to resistance (p = 0.011), shorter disease-free survival (p = 0.001) and overall survival (p = 0.026) and was also a risk factor for relapse (p = 0.002) and death (p = 0.032). The association between IKK2 and NF-κB positivity predicted a subgroup with shorter overall survival (p = 0.004), disease-free survival (p = 0.003) and resistance to platinum-based chemotherapy (p = 0.036). NF-κB positivity was associated with worse overall survival (p = 0.005) and disease-free survival (p = 0.027) and was a positive predictor for relapse (p = 0.032) and death (p = 0.008). Higher expression of GRIM-19 was associated with higher disease-free survival (p = 0.039) and was a negative predictor for relapse (p = 0.046).

CONCLUSIONS

GRIM-19 is a potential predictor of prognosis and disease recurrence in HGSC. IKK2 and NF-κB are related to poor prognosis and are potential predictors of response to platinum-based chemotherapy in HGSC. IHC analyses of GRIM19, IKK2 and NF-κB may be important in the attempt to provide prognostic values for relapse and response to treatment in patients with HGSC.

Nuclear factor-kappa B1 inhibits early apoptosis of glioma cells by promoting the expression of Bcl-2

Glioma is one of the most common types of adult primary brain tumors, and the underlying molecular mechanisms still remain unclear. Nuclear factor-kappa B1 (NF-κB1) is involved in a variety of malignancies and is widely expressed in malignant tumors. However, the expression of NF-κB1 in different grades of glioma, the correlation between NF-κB1 and Bcl-2 expressions in gliomas, and the research between NF-κB1 and early apoptosis of glioma cells have not been reported so far. In this study, the expression level of NF-κB1 in 31 human glioma tissues and six nonneoplastic brain tissues was determined using quantitative real-time polymerase chain reaction. Results showed that the expression of NF-κB1 in human glioma tissues and glioma cell lines, SHG44 and U87, was significantly higher compared to noncancerous brain tissues and that the expression increased with increasing degrees of tumor malignancy. Similar results were demonstrated with the expression of Bcl-2 in the same human glioma specimens. Flow cytometry results showed that inhibition of NF-κB1 expression significantly promoted apoptosis of SHG44 and U87 in human glioma cells. Western blot analysis further confirmed decreased expression of Bcl-2 protein after inhibition of NF-κB1 protein expression. Taken together, NF-κB1 overexpression inhibits early apoptosis of glioma cells and high expression of NF-κB1 promotes the expression of antiapoptotic gene Bcl-2. Therefore, our study results provide a theoretical basis for antiapoptotic mechanism of tumor cells in association with NF-κB1.

The relationship of REL proto-oncogene to pathobiology and chemoresistance in follicular and transformed follicular lymphoma

Follicular lymphoma (FL) is a common type of indolent lymphoma that occasionally transforms to more aggressive B-cell lymphomas. These transformed follicular lymphomas (tFL) are often associated with chemoresistance whose mechanisms are currently unknown. REL, a proto-oncogene located on frequently amplified 2p16.1-p15 locus, promotes tumorigenesis in many cancer types through deregulation of the NF-κB pathway; however, its role in FL pathobiology or chemoresistance has not been addressed. Here, we evaluated REL gene copy number by q-PCR on FFPE FL tumor samples, and observed REL amplification in 30.4% of FL cases that was associated with weak elevation of transcript levels. PCR-Sanger analysis did not show any somatic mutation in FL tumors. In support of a marginal oncogenic role, a REL-transduced FL cell line was positively selected under limiting serum conditions. Interestingly, reanalysis of previously reported gene expression profiles revealed significant enrichment of DNA damage-induced repair and cell cycle arrest pathways in tFL tumors with high REL expression compared to those with low REL expression consistent with the critical role of c-REL in genotoxicity-induced NF-κB signaling, which was reported to lead to drug resistance. In addition to DNA damage repair genes such as ATM and BRCA1, anti-apoptotic BCL2 was significantly elevated in REL-high FL and tFL tumors. Altogether these data suggest that other genes located in amplified 2p16.1-p15 locus may have more oncogenic role in FL etiology; however, high REL expression may be useful as a predictive biomarker of response to immunochemotherapy, and inhibition of c-REL may potentially sensitize resistant FL or tFL cells to chemotherapy.