Regulatory Network of ARF in Cancer Development

The Prognostic and Therapeutic Roles of ARL-6 Gene in Hepatocellular Carcinoma

Background: Hepatocellular carcinoma (HCC) is one of the most prevalent human cancers. ARL-6, a member of the ADP ribosylation factor (like) (ARF) protein family, has gained attention as a potential therapeutic target in various malignancies and a prognostic biomarker. However, its specific roles in HCC, both prognostically and biochemically, remain largely unclear. Methods: To examine the functional relevance of ARL-6 in HCC, we acquired data from GEPIA, UALCAN, TIMER, TCGA, GeneMANIA, and Metascape databases. Then, we conducted immunohistochemistry on a replication sample comprising 26 HCC specimens to assess the efficacy of the ARL-6 gene. To unravel the mechanistic intricacies, we employed diverse assays such as the cell counting kit 8 (CCK8), flow cytometry, and transwell invasion assessment. Results: Our findings demonstrated the mRNA expression of ARL-6 was significantly upregulated in HCC compared to normal tissue, as evidenced by comprehensive database analysis. Immunohistochemistry further revealed that ARL-6 expression was remarkably higher in HCC than in para-carcinoma tissues. Moreover, ARL-6 expression exhibited noteworthy variations across diverse LIHC characteristics, including sample type, histological subtype, TP53 mutation status, nodal metastatic status, and cancer stage. In addition, high transcriptional levels of ARL-6 were correlated with diminished overall survival (OS) and disease-free survival (DFS) in HCC patients. Furthermore, our study indicated positive correlations between ARL-6 expression levels and the activities of tumor-infiltrating immune cells such as B cells, myeloid dendritic cells, macrophages, neutrophils, CD8+T cells, and CD4+T cells. Substantiating our findings, database analysis uncovered additional evidence of ARL-6 gene co-expression and its functional significance in HCC cases. Finally, we demonstrated the involvement of the ARL-6 gene in HCC cell invasion, proliferation, and apoptosis. Conclusions: In conclusion, our investigation sheds light on the pivotal role of ARL-6 in influencing HCC prognosis and treatment by modulating the biological activities of tumor cells. These discoveries hold promise for the development of predictive biomarkers and novel therapeutic avenues for affected patients.

Asymptomatic Survivors of Childhood Acute Lymphoblastic Leukemia Demonstrate a Biological Profile of Inflamm-Aging Early in Life

Childhood acute lymphoblastic leukemia (ALL) survivors are at higher risk of developing many late effects later in life. They experience multiple health problems that have significant public health implications, such as frailty, premature onset of lifestyle diseases, and second tumors. There is some evidence that chronic inflammation causes accelerated aging in childhood cancer survivors; however, the available data are very limited. The aim of the study was to evaluate the broad panel of cytokines among asymptomatic ALL survivors after anticancer treatment. The study included 56 subjects with a mean age of 16.11 ± 3.98 years. The commercially available Bio-Plex Pro Human Cytokine Screening 48-Plex Panel Assay and Bio-Plex TGF-β Assay were used for simultaneous determination of 48 cytokines and 3 isoforms of TGF-β. Among 51 tested cytokines, the levels of 33 were statistically significantly higher in ALL survivors than in the control group (p < 0.05). Increased levels of pro-inflammatory cytokines, including the IL-1 family (IL-1 β, IL-1Ra; p < 0.0001), IL-6 (p < 0.001), IL-17 (p < 0.001), IL-18 (p < 0.05), TNFα (p < 0.01), IFNα2 (p < 0.05), and IFNγ (p < 0.01), were found elevated in the entire study group, compared with the controls. Subjects treated previously according to the high-risk protocol had higher IL-18 levels than low- and intermediate-risk groups (p < 0.05). Elevated levels of IL-1ra, IL-6, IL-12 (p70), IL-17, LIF, M-CSF, CSF, and VEGF were found in ALL survivors treated before the age of 5, compared with subjects treated over 5 years of age (p < 0.05). Moreover, individuals who received radiotherapy presented elevated levels of both IL-18 (p < 0.05) and MIG (p < 0.05). In conclusion, we found that young asymptomatic survivors after ALL treatment demonstrated a biological profile of complex low-grade chronic inflammation.

An Update to Hallmarks of Cancer

In the last decade, there has been remarkable progress in research toward understanding and refining the hallmarks of cancer. In this review, we propose a new hallmark - “pro-survival autophagy.” The importance of pro-survival autophagy is well established in tumorigenesis, as it is related to multiple steps in cancer progression and vital for some cancers. Autophagy is a potential anti-cancer therapeutic target. For this reason, autophagy is a good candidate as a new hallmark of cancer. We describe two enabling characteristics that play a major role in enabling cells to acquire the hallmarks of cancer - “tumor-promoting microenvironment and macroenvironment” and “cancer epigenetics, genome instability and mutation.” We also discuss the recent updates, therapeutic and prognostic implications of the eight hallmarks of cancer described by Hanahan et al. in 2011. Understanding these hallmarks and enabling characteristics is key not only to developing new ways to treat cancer efficiently but also to exploring options to overcome cancer resistance to treatment.

Establishment of the TBX-code reveals aberrantly activated T-box gene TBX3 in Hodgkin lymphoma

T-box genes encode transcription factors which control basic processes in development of several tissues including cell differentiation in the hematopoietic system. Here, we analyzed the physiological activities of all 17 human T-box genes in early hematopoiesis and in lymphopoiesis including developing and mature B-cells, T-cells, natural killer (NK)-cells and innate lymphoid cells. The resultant expression pattern comprised six genes, namely EOMES, MGA, TBX1, TBX10, TBX19 and TBX21. We termed this gene signature TBX-code which enables discrimination of normal and aberrant activities of T-box genes in lymphoid malignancies. Accordingly, expression analysis of T-box genes in Hodgkin lymphoma (HL) patients using a public profiling dataset revealed overexpression of EOMES, TBX1, TBX2, TBX3, TBX10, TBX19, TBX21 and TBXT while MGA showed aberrant downregulation. Analysis of T-cell acute lymphoid leukemia patients indicated aberrant overexpression of six T-box genes while no deregulated T-box genes were detected in anaplastic large cell lymphoma patients. As a paradigm we focused on TBX3 which was ectopically activated in about 6% of HL patients analyzed. Normally, TBX3 is expressed in tissues like lung, adrenal gland and retina but not in hematopoiesis. HL cell line KM-H2 expressed enhanced TBX3 levels and was used as an in vitro model to identify upstream regulators and downstream targets in this malignancy. Genomic studies of this cell line showed focal amplification of the TBX3 locus at 12q24 which may underlie its aberrant expression. In addition, promoter analysis and comparative expression profiling of HL cell lines followed by knockdown experiments revealed overexpressed transcription factors E2F4 and FOXC1 and chromatin modulator KDM2B as functional activators. Furthermore, we identified repressed target genes of TBX3 in HL including CDKN2A, NFKBIB and CD19, indicating its respective oncogenic function in proliferation, NFkB-signaling and B-cell differentiation. Taken together, we have revealed a lymphoid TBX-code and used it to identify an aberrant network around deregulated T-box gene TBX3 in HL which promotes hallmark aberrations of this disease. These findings provide a framework for future studies to evaluate deregulated T-box genes in lymphoid malignancies.

MiR-6838-5p facilitates the proliferation and invasion of renal cell carcinoma cells through inhibiting the DMTF1/ARF-p53 axis

Renal cell carcinoma (RCC) is one of the most common renal malignancies in the urinary system. Numerous studies have demonstrated that miRNAs can regulate tumorigenesis and progression. This study aims to investigate the role and regulatory mechanism of miR-6838-5p in RCC. Our study confirmed that miR-6838-5p was upregulated in human RCC tissues (30/42, 77.43%, P < 0.01) and RCC cell lines (P < 0.05) compared to adjacent non-neoplastic tissues and normal renal epithelial cells. In vitro, overexpression of miR-6838-5p enhanced cell proliferation and invasion in human RCC cell lines (ACHN and 786-O), which were detected by CCK-8, Transwell and Colony formation assays (P < 0.05), and knockdown of miR-6838-5p suppressed cell proliferation and invasion (P < 0.05). Results of Bioinformatics analysis combined with Dual-luciferase reporter gene assay demonstrated that miR-6838-5p could bind to Cyclin D binding myb-like transcription factor 1 (DMTF1). In addition, RT-qPCR and Western blotting confirmed that DMTF1 was downregulated in RCC tissues and cell lines. Meanwhile, it was demonstrated that overexpression of miR-6838-5p inhibited DMTF1 level in ACHN cells. Next, we confirmed that DMTF1 overexpression reversed the inhibitory effects of overexpression of miR-6838-5p on phosphatase and tensin homolog (PTEN), tumor protein 53(p53), murine double minute 2 (MDM2) and alternative reading frame (ARF) protein levels in the ARF-p53 signaling pathway. In conclusion, our research showed that miR-6838-5p enhanced the proliferation and invasion of RCC cells by inhibiting the DMTF1/ARF-p53 axis.

G protein coupled receptor kinase 5 modifies the nucleolar stress response activated by actinomycin D

G protein coupled receptor kinase 5 (GRK5) is localized within the nucleus and moderates functions such as DNA transcription, in addition to its localization at the plasma membrane. In this report, we show that GRK5 modifies the nucleolar stress response activated by the DNA polymerase inhibitor, actinomycin D (ActD). We show an increased sensitivity to the apoptotic effects of ActD on cervical HeLa cells and the breast cancer cell line MDA MB 231 with reduced protein expression of GRK5. We also tested two types of breast cancer cells (MDA MB 231 and MCF7 cells) and found that the rate of response to ActD varied between them because they have innate differences in the protein expression of GRK5. We also found that GRK5 phosphorylates nucleophosmin (NPM1) at T199 before and during the early stages of ActD treatment. Phosphorylation at T199 increases the ability of NPM1 to interact with p14^ARF in vitro, which may affect the protein expression levels of p14^ARF. We found that the expression levels of p14^ARF were lower in the cells transfected with the control shRNA, but higher in cells transfected with GRK5 shRNA. Collectively, this suggests that GRK5 modifies the nucleolar stress response associated with ActD.

Cancer Treatment-Induced Accelerated Aging in Cancer Survivors: Biology and Assessment

Rapid improvements in cancer survival led to the realization that many modalities used to treat or control cancer may cause accelerated aging in cancer survivors. Clinically, "accelerated aging" phenotypes in cancer survivors include secondary cancers, frailty, chronic organ dysfunction, and cognitive impairment, all of which can impact long-term health and quality of life in cancer survivors. The treatment-induced accelerated aging in cancer survivors could be explained by telomere attrition, cellular senescence, stem cell exhaustion, DNA damage, and epigenetic alterations. Several aging clocks and biomarkers of aging have been proposed to be potentially useful in estimating biological age, which can provide specific information about how old an individual is biologically independent of chronological age. Measuring biological age in cancer survivors may be important for two reasons. First, it can better predict the risk of cancer treatment-related comorbidities than chronological age. Second, biological age may provide additional value in evaluating the effects of treatments and personalizing cancer therapies to maximize efficacy of treatment. A deeper understanding of treatment-induced accelerated aging in individuals with cancer may lead to novel strategies that reduce the accelerated aging and improve the quality of life in cancer survivors.

Roles of ARF tumour suppressor protein in lung cancer: time to hit the nail on the head!

Owing to its poor prognosis, the World Health Organization (WHO) lists lung cancer on top of the list when it comes to growing mortality rates and incidence. Usually, there are two types of lung cancer, small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC), which also includes adenocarcinoma, squamous cell carcinoma and large cell carcinomas. ARF, also known in humans as p14ARF and in the mouse as p19ARF, is a nucleolar protein and a member of INK4, a family of cyclin-independent kinase inhibitors (CKI). These genes are clustered on chromosome number 9p21 within the locus of CDKN2A. NSCLC has reported the role of p14ARF as a potential target. p14ARF has a basic mechanism to inhibit mouse double minute 2 protein that exhibits inhibitory action on p53, a phosphoprotein tumour suppressor, thus playing a role in various tumour-related activities such as growth inhibition, DNA damage, autophagy, apoptosis, cell cycle arrest and others. Extensive cancer research is ongoing and updated reports regarding the role of ARF in lung cancer are available. This article summarizes the available lung cancer ARF data, its molecular mechanisms and its associated signalling pathways. Attempts have been made to show how p14ARF functions in different types of lung cancer providing a thought to look upon ARF as a new target for treating the debilitating condition of lung cancer.

Association of SNPs in CDKN2A (P14ARF) Tumour Suppressor Gene With Endometrial Cancer in Postmenopausal Women

BACKGROUND/AIM

This research was aimed to evaluate the association between three selected single nucleotide polymorphisms (SNPs) within the CDKN2A (P14ARF) tumour suppressor gene and the incidence of endometrial cancer (EC) in postmenopausal women.

PATIENTS AND METHODS

The study included 194 postmenopausal women; 144 with EC and 50 non-cancer controls. Genotypes in P14ARF rs3088440, rs3731217 and rs3731245 polymorphisms were assayed using PCR-RFLP and confirmed by sequencing.

RESULTS

Regarding the rs3088440 polymorphism, CT, and CT-TT genotypes, were more prevalent among EC patients than in controls (OR=5.55, p=0.023, OR=5.29, p=0.027; and OR=2.92, p=0.023, respectively). The T allele within rs3088440 was more prevalent in EC females than in controls (χ²=4.7, p=0.030). Considering rs3731217, TG and TG-GG genotypes were less prevalent among EC (OR=0.34, p=0.024 or p=0.023; and OR=0.38, p=0.035, respectively).

CONCLUSION

Polymorphisms in the CDKN2A gene are associated with EC in postmenopausal women.

Post-Translational Regulation of ARF: Perspective in Cancer

Tumorigenesis can be induced by various stresses that cause aberrant DNA mutations and unhindered cell proliferation. Under such conditions, normal cells autonomously induce defense mechanisms, thereby stimulating tumor suppressor activation. ARF, encoded by the CDKN2a locus, is one of the most frequently mutated or deleted tumor suppressors in human cancer. The safeguard roles of ARF in tumorigenesis are mainly mediated via the MDM2-p53 axis, which plays a prominent role in tumor suppression. Under normal conditions, low p53 expression is stringently regulated by its target gene, MDM2 E3 ligase, which induces p53 degradation in a ubiquitin-proteasome-dependent manner. Oncogenic signals induced by MYC, RAS, and E2Fs trap MDM2 in the inhibited state by inducing ARF expression as a safeguard measure, thereby activating the tumor-suppressive function of p53. In addition to the MDM2-p53 axis, ARF can also interact with diverse proteins and regulate various cellular functions, such as cellular senescence, apoptosis, and anoikis, in a p53-independent manner. As the evidence indicating ARF as a key tumor suppressor has been accumulated, there is growing evidence that ARF is sophisticatedly fine-tuned by the diverse factors through transcriptional and post-translational regulatory mechanisms. In this review, we mainly focused on how cancer cells employ transcriptional and post-translational regulatory mechanisms to manipulate ARF activities to circumvent the tumor-suppressive function of ARF. We further discussed the clinical implications of ARF in human cancer.

Melanoma stem cell maintenance and chemo-resistance are mediated by CD133 signal to PI3K-dependent pathways

Melanoma stem cells (MSCs) are characterized by their unique cell surface proteins and aberrant signaling pathways. These stemness properties are either in a causal or consequential relationship to melanoma progression, treatment resistance and recurrence. The functional analysis of CD133⁺ and CD133^- cells in vitro and in vivo revealed that melanoma progression and treatment resistance are the consequences of CD133 signal to PI3K pathway. CD133 signal to PI3K pathway drives two downstream pathways, the PI3K/Akt/MDM2 and the PI3K/Akt/MKP-1 pathways. Activation of PI3K/Akt/MDM2 pathway results in the destabilization of p53 protein, while the activation of PI3K/Akt/MKP-1 pathway results in the inhibition of mitogen-activated protein kinases (MAPKs) JNK and p38. Activation of both pathways leads to the inhibition of fotemustine-induced apoptosis. Thus, the disruption of CD133 signal to PI3K pathway is essential to overcome Melanoma resistance to fotemustine. The pre-clinical verification of in vitro data using xenograft mouse model of MSCs confirmed the clinical relevance of CD133 signal as a therapeutic target for melanoma treatment. In conclusion, our study provides an insight into the mechanisms regulating MSCs growth and chemo-resistance and suggested a clinically relevant approach for melanoma treatment.

CDKs in Sarcoma: Mediators of Disease and Emerging Therapeutic Targets

Sarcomas represent one of the most challenging tumor types to treat due to their diverse nature and our incomplete understanding of their underlying biology. Recent work suggests cyclin-dependent kinase (CDK) pathway activation is a powerful driver of sarcomagenesis. CDK proteins participate in numerous cellular processes required for normal cell function, but their dysregulation is a hallmark of many pathologies including cancer. The contributions and significance of aberrant CDK activity to sarcoma development, however, is only partly understood. Here, we describe what is known about CDK-related alterations in the most common subtypes of sarcoma and highlight areas that warrant further investigation. As disruptions in CDK pathways appear in most, if not all, subtypes of sarcoma, we discuss the history and value of pharmacologically targeting CDKs to combat these tumors. The goals of this review are to (1) assess the prevalence and importance of CDK pathway alterations in sarcomas, (2) highlight the gap in knowledge for certain CDKs in these tumors, and (3) provide insight into studies focused on CDK inhibition for sarcoma treatment. Overall, growing evidence demonstrates a crucial role for activated CDKs in sarcoma development and as important targets for sarcoma therapy.

Low-grade serous ovarian carcinoma: an evolution toward targeted therapy

Low-grade serous ovarian carcinoma and its high-grade serous ovarian carcinoma counterpart differ in their precursor lesions, molecular profile, natural history, and response to therapies. As such, low-grade serous ovarian carcinoma needs to be studied separately from high-grade serous ovarian carcinoma, despite challenges stemming from its rarity. A deeper understanding of the pathogenesis of low-grade serous ovarian carcinoma and the most common molecular defects and pathways involved in the carcinogenesis of the ovarian epithelium from normal to serous borderline ovarian tumors to low-grade serous ovarian carcinoma will help develop better therapies. By adopting targeted approaches there may be an opportunity to integrate novel therapies without the need for robust numbers in clinical trials. This manuscript will discuss low-grade serous ovarian carcinoma and focus on the arising treatments being developed with an improved understanding of the pathogenesis of this disease.

STAT3 and STAT5 Activation in Solid Cancers

The Signal Transducer and Activator of Transcription (STAT)3 and 5 proteins are activated by many cytokine receptors to regulate specific gene expression and mitochondrial functions. Their role in cancer is largely context-dependent as they can both act as oncogenes and tumor suppressors. We review here the role of STAT3/5 activation in solid cancers and summarize their association with survival in cancer patients. The molecular mechanisms that underpin the oncogenic activity of STAT3/5 signaling include the regulation of genes that control cell cycle and cell death. However, recent advances also highlight the critical role of STAT3/5 target genes mediating inflammation and stemness. In addition, STAT3 mitochondrial functions are required for transformation. On the other hand, several tumor suppressor pathways act on or are activated by STAT3/5 signaling, including tyrosine phosphatases, the sumo ligase Protein Inhibitor of Activated STAT3 (PIAS3), the E3 ubiquitin ligase TATA Element Modulatory Factor/Androgen Receptor-Coactivator of 160 kDa (TMF/ARA160), the miRNAs miR-124 and miR-1181, the Protein of alternative reading frame 19 (p19ARF)/p53 pathway and the Suppressor of Cytokine Signaling 1 and 3 (SOCS1/3) proteins. Cancer mutations and epigenetic alterations may alter the balance between pro-oncogenic and tumor suppressor activities associated with STAT3/5 signaling, explaining their context-dependent association with tumor progression both in human cancers and animal models.

First Days in the Life of Naive Human B Lymphocytes Infected with Epstein-Barr Virus

Epstein-Barr virus (EBV) infects and activates resting human B lymphocytes, reprograms them, induces their proliferation, and establishes a latent infection in them. In established EBV-infected cell lines, many viral latent genes are expressed. Their roles in supporting the continuous proliferation of EBV-infected B cells in vitro are known, but their functions in the early, prelatent phase of infection have not been investigated systematically. In studies during the first 8 days of infection using derivatives of EBV with mutations in single genes of EBVs, we found only Epstein-Barr nuclear antigen 2 (EBNA2) to be essential for activating naive human B lymphocytes, inducing their growth in cell volume, driving them into rapid cell divisions, and preventing cell death in a subset of infected cells. EBNA-LP, latent membrane protein 2A (LMP2A), and the viral microRNAs have supportive, auxiliary functions, but mutants of LMP1, EBNA3A, EBNA3C, and the noncoding Epstein-Barr virus with small RNA (EBERs) had no discernible phenotype compared with wild-type EBV. B cells infected with a double mutant of EBNA3A and 3C had an unexpected proliferative advantage and did not regulate the DNA damage response (DDR) of the infected host cell in the prelatent phase. Even EBNA1, which has very critical long-term functions in maintaining and replicating the viral genomic DNA in established cell lines, was dispensable for the early activation of infected cells. Our findings document that the virus dose is a decisive parameter and indicate that EBNA2 governs the infected cells initially and implements a strictly controlled temporal program independent of other viral latent genes. It thus appears that EBNA2 is sufficient to control all requirements for clonal cellular expansion and to reprogram human B lymphocytes from energetically quiescent to activated cells.IMPORTANCE The preferred target of Epstein-Barr virus (EBV) is human resting B lymphocytes. We found that their infection induces a well-coordinated, time-driven program that starts with a substantial increase in cell volume, followed by cellular DNA synthesis after 3 days and subsequent rapid rounds of cell divisions on the next day accompanied by some DNA replication stress (DRS). Two to 3 days later, the cells decelerate and turn into stably proliferating lymphoblast cell lines. With the aid of 16 different recombinant EBV strains, we investigated the individual contributions of EBV's multiple latent genes during early B-cell infection and found that many do not exert a detectable phenotype or contribute little to EBV's prelatent phase. The exception is EBNA2 that is essential in governing all aspects of B-cell reprogramming. EBV relies on EBNA2 to turn the infected B lymphocytes into proliferating lymphoblasts preparing the infected host cell for the ensuing stable, latent phase of viral infection. In the early steps of B-cell reprogramming, viral latent genes other than EBNA2 are dispensable, but some, EBNA-LP, for example, support the viral program and presumably stabilize the infected cells once viral latency is established.

The nucleolus, an ally, and an enemy of cancer cells

The rates of ribosome production by a nucleolus and of protein biosynthesis by ribosomes are tightly correlated with the rate of cell growth and proliferation. All these processes must be matched and appropriately regulated to provide optimal cell functioning. Deregulation of certain factors, including oncogenes, controlling these processes, especially ribosome biosynthesis, can lead to cell transformation. Cancer cells are characterized by intense ribosome biosynthesis which is advantageous for their growth and proliferation. On the other hand, this feature can be engaged as an anticancer strategy. Numerous nucleolar factors such as nucleolar and ribosomal proteins as well as different RNAs, in addition to their role in ribosome biosynthesis, have other functions, including those associated with cancer biology. Some of them can contribute to cell transformation and cancer development. Others, under stress evoked by different factors which often hamper function of nucleoli and thus induce nucleolar/ribosomal stress, can participate in combating cancer cells. In this sense, intentional application of therapeutic agents affecting ribosome biosynthesis can cause either release of these molecules from nucleoli or their de novo biosynthesis to mediate the activation of pathways leading to elimination of harmful cells. This review underlines the role of a nucleolus not only as a ribosome constituting apparatus but also as a hub of both positive and negative control of cancer development. The article is mainly based on original papers concerning mechanisms in which the nucleolus is implicated directly or indirectly in processes associated with neoplasia.