Potential Oncogenic Function Research Articles

Modelling quiescence exit of neural stem cells reveals a FOXG1-FoxO6 axis.

The molecular mechanisms controlling the balance of quiescence and proliferation in adult neural stem cells (NSCs) are often deregulated in brain cancers such as glioblastoma (GBM). Previously, we reported that FOXG1, a forebrain-restricted neurodevelopmental transcription factor, is frequently upregulated in glioblastoma stem cells (GSCs) and limits the effects of cytostatic pathways, in part by repression of the tumour suppressor Foxo3. Here, we show that increased FOXG1 upregulates FoxO6, a more recently discovered FoxO family member with potential oncogenic functions. Although genetic ablation of FoxO6 in proliferating NSCs has no effect on the cell cycle or entry into quiescence, we find that FoxO6-null NSCs can no longer efficiently exit quiescence following FOXG1 elevation. Increased FoxO6 results in the formation of large acidic vacuoles, reminiscent of Pak1-regulated macropinocytosis. Consistently, Pak1 expression is upregulated by FOXG1 overexpression and downregulated upon FoxO6 loss in proliferative NSCs. These data suggest a pro-oncogenic role for FoxO6, downstream of GBM-associated elevated FOXG1, in controlling quiescence exit, and shed light on the potential functions of this underexplored FoxO family member.

The Overexpressed MicroRNAs miRs-182, 155, 493, 454, and U6 snRNA and Underexpressed let-7c, miR-328, and miR-451a as Potential Biomarkers in Invasive Breast Cancer and Their Clinicopathological Significance.

Breast cancer comprises the leading cause of cancer-related death in women. MicroRNAs (miRNAs) have emerged as important factors with concern to carcinogenesis and have potential for use as biomarkers. This study provides a comprehensive evaluation of the microRNA expression in invasive breast carcinoma of no special type tissues compared with benign tissues via large-scale screening and the candidate-specific validation of 15 miRNAs and U6 snRNA applying qPCR and the examination of clinicopathological data. Of the six downregulated miRNAs, let-7c was identified as the most promising miRNA biomarker and its lower expression was linked with Ki-67 positivity, luminal B versus luminal A samples, multifocality, lymph node metastasis, and inferior PFS. Of the 9 upregulated sncRNAs, the data on U6 snRNA, miR-493 and miR-454 highlighted their potential oncogenic functions. An elevated U6 snRNA expression was associated with the tumor grade, Ki-67 positivity, luminal B versus A samples, lymph node metastasis, and worsened PFS (and OS) outcomes. An elevated miR-454 expression was detected in higher grades, Ki-67 positive and luminal B versus A samples. Higher miR-493 levels were noted for the tumor stage (and grade) and worse patient outcomes (PFS, OS). The data also suggested that miR-451a and miR-328 may have tumor suppressor roles, and miR-182 and miR-200c pro-oncogenic functions, while the remaining sncRNAs did not evince any significant associations. We showed particular microRNAs and U6 snRNA as differentially expressed between tumors and benign tissues and associated with clinicopathological parameters, thus potentially corresponding with important roles in breast carcinogenesis. Their importance should be further investigated and evaluated in follow-up studies to reveal their potential in clinical practice.

Prognostic and predictive value of super-enhancer-derived signatures for survival and lung metastasis in osteosarcoma

BackgroundRisk stratification and personalized care are crucial in managing osteosarcoma due to its complexity and heterogeneity. However, current prognostic prediction using clinical variables has limited accuracy. Thus, this study aimed to explore potential molecular biomarkers to improve prognostic assessment.MethodsHigh-throughput inhibitor screening of 150 compounds with broad targeting properties was performed and indicated a direction towards super-enhancers (SEs). Bulk RNA-seq, scRNA-seq, and immunohistochemistry (IHC) were used to investigate SE-associated gene expression profiles in osteosarcoma cells and patient tissue specimens. Data of 212 osteosarcoma patients who received standard treatment were collected and randomized into training and validation groups for retrospective analysis. Prognostic signatures and nomograms for overall survival (OS) and lung metastasis-free survival (LMFS) were developed using Cox regression analyses. The discriminatory power, calibration, and clinical value of nomograms were evaluated.ResultsHigh-throughput inhibitor screening showed that SEs significantly contribute to the oncogenic transcriptional output in osteosarcoma. Based on this finding, focus was given to 10 SE-associated genes with distinct characteristics and potential oncogenic function. With multi-omics approaches, the hyperexpression of these genes was observed in tumor cell subclusters of patient specimens, which were consistently correlated with poor outcomes and rapid metastasis, and the majority of these identified SE-associated genes were confirmed as independent risk factors for poor outcomes. Two molecular signatures were then developed to predict survival and occurrence of lung metastasis: the SE-derived OS-signature (comprising LACTB, CEP55, SRSF3, TCF7L2, and FOXP1) and the SE-derived LMFS-signature (comprising SRSF3, TCF7L2, FOXP1, and APOLD1). Both signatures significantly improved prognostic accuracy beyond conventional clinical factors.ConclusionsOncogenic transcription driven by SEs exhibit strong associations with osteosarcoma outcomes. The SE-derived signatures developed in this study hold promise as prognostic biomarkers for predicting OS and LMFS in patients undergoing standard treatments. Integrative prognostic models that combine conventional clinical factors with these SE-derived signatures demonstrate substantially improved accuracy, and have the potential to facilitate patient counseling and individualized management.

NamiRNA-mediated high expression of KNSTRN correlates with poor prognosis and immune infiltration in hepatocellular carcinoma.

Mutations of kinetochore-localized astrin/sperm-associated antigen 5 (KNSTRN) can interfere with chromatid cohesion, increase aneuploidy in tumours, and enhance tumourigenesis. However, the role of the KNSTRN-binding protein in hepatocellular carcinoma (HCC) remains unclear. Using The Cancer Genome Atlas databases, we investigated the potential oncogenic functions of KNSTRN in HCC along with R and various computational tools. Detailed results revealed that elevated expression of KNSTRN was considerably associated with poor overall survival (HR = 1.48, 95% CI: 1.05-2.09, p = 0.027) and progress-free interval (HR = 1.41, 95% CI: 1.05-1.89, p = 0.021) in HCC. Gene ontology/Kyoto Encyclopedia of Genes and Genomes functional enrichment analysis showed that KNSTRN is closely related to organelle fission, chromosomal region, tubulin binding, and cell cycle signalling pathway. TIMER database analysis showed the correlations between KNSTRN expression and tumour-infiltrating immune cells, biomarkers of immune cells, and immune checkpoint expression. Moreover, the KNSTRN level was significantly positively associated with immunosuppressive cells in the tumour microenvironment, including regulatory T-cells, myeloid-derived suppressor cells, and cancer-associated fibrocytes. Finally, a possible nuclear activating miRNA (NamiRNA)-enhancer network of hsa-miR-107, which activates the KNSTRN expression in liver hepatocellular carcinoma, was constructed by correlation analysis. NamiRNA-mediated upregulation of KNSTRN correlated with poor prognosis and tumour immune infiltration in HCC. KNSTRN could serve as an effective biomarker for the diagnosis and prognosis of HCC and support the development of novel therapeutic strategies.

Abstract 5834: Examining the potential oncogenic function of septins and their interaction with Chmp1A tumor suppressor in pancreatic cancer

Abstract Introduction: Chmp1A functions as a tumor suppressor by the activation of ATM and p53 in pancreatic cancer. The nuclear localization signal (NLS) of Chmp1A is required for cell growth inhibition and activation of ATM and p53. Proteomic analysis has identified Septins (a group of GTP-binding proteins) to be associated with the NLS-deleted Chmp1A. Since NLS-deleted Chmp1A promotes cancer cell growth, we hypothesized that Septins may function as oncogenes and that Chmp1A functions as a tumor suppressor partly by inhibiting the oncogenic action of Septin proteins. Objective: To examine whether Septin proteins exhibit oncogenic activity and to investigate whether Chmp1A inhibits the oncogenic function of Septins. Methodology: Using normal pancreatic and cancer cells, we compared Septin transcripts using PCR assays, Septin protein expression using Western blot, and Septin cellular expression using immunocytochemistry. We performed immunohistochemical analysis to examine whether Septin expression is increased in pancreatic cancer tissues compared to corresponding normal tissues. Silencing technology was used to test whether Septin expression is regulated by Chmp1A. Results: Our preliminary data indicates that the transcript and protein of Septins are increased in various pancreatic cancer cell lines compared to normal. Septin protein expression was increased or altered in human pancreatic ductal adenocarcinoma tissues compared to corresponding normal tissues. Additionally, our data implies that Chmp1A negatively regulates Septin expression, since Septin transcripts and proteins are increased when Chmp1A protein is silenced. Summary and future direction: Our data suggests that Septin functions as an oncogene in pancreatic cancer cells and that Chmp1A functions as a tumor suppressor partly by inhibiting the oncogenic action of Septin proteins. For the completion of the project in the future, we plan to confirm the function of Septins by investigating the effect of Septin overexpression on pancreatic cancer cell proliferation. In addition, we will further investigate the interaction between Septins and Chmp1A by examining Septin expression and localization in pancreatic cancer cells that overexpress Chmp1A. Citation Format: Mei Cai, Joseph Amor, Maiyon Park. Examining the potential oncogenic function of septins and their interaction with Chmp1A tumor suppressor in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5834.

Characterizing kinase intergenic-breakpoint rearrangements in a large-scale lung cancer population and real-world clinical outcomes

BackgroundKinase gene fusions are strong driver mutations in neoplasia; however, kinase intergenic-breakpoint rearrangements (IGRs) confound the detection of such fusions and of targeted treatments. We aim to provide an overview of kinase IGRs in a large lung cancer cohort and examine real-world survival outcomes of patients with such fusions.MethodsMutational profiles analyzed using targeted next-generation sequencing of 425 cancer-related genes between June 2016 and July 2019 were retrospectively reviewed. Patients’ demographic data, clinical characteristics, and survivals were analyzed. RNA sequencing or immunohistochemical assays were carried out to verify chimeric fusion products.ResultsWe identified 3411 patients with kinase fusions from a cohort of 30 450 patients with lung cancer, and 624 kinase IGR events were identified in 538 of the 3411 patients. The most frequently identified kinase genes included anaplastic lymphoma kinase (ALK), RET proto-oncogene (RET), ROS proto-oncogene 1 (ROS1), Erb-B2 receptor tyrosine kinase 2/3 (ERBB2/3), and epidermal growth factor receptor (EGFR). Our data showed that most (67%) kinase IGRs occurred on the same chromosome and kinase domains remained intact at the 3′-end. Approximately 3% (19/624) of the kinase IGRs had one genomic breakpoint located in gene promoter regions, including nine fusion events involving ALK, RET, ROS1, EGFR, ERBB2, or fibroblast growth factor receptor 3 (FGFR3). Among the 538 patients with kinase IGRs, 167 (31%) lacked oncogenic driver mutations, among which 28 received targeted therapies in real-world practice. Notably, three ALK IGR patients who harbored no canonical oncogenic aberrations were confirmed with an EML4-ALK chimeric fusion product by RNA sequencing and/or ALK immunohistochemical assays. One patient demonstrated a favorable clinical outcome after 14 months on crizotinib. An additional two patients who had ROS1 IGRs demonstrated a clinical benefit after 13 and 19 months on crizotinib, respectively.ConclusionA large real-world lung cancer cohort with kinase IGRs was comprehensively analyzed for their molecular characteristics. The data indicated the potential oncogenic function of kinase IGRs and their outcomes following the administration of targeted therapies.

An oncogenic splice variant of PDGFR\u03b1 in adult glioblastoma as a therapeutic target for selective CDK4/6 inhibitors

Understanding human genome alterations is necessary to optimize genome-based cancer therapeutics. However, some newly discovered mutations remain as variants of unknown significance (VUS). Here, the mutation c.1403A > G in exon 10 of the platelet-derived growth factor receptor-alpha (PDGFRA) gene, a VUS found in adult glioblastoma multiforme (GBM), was introduced in human embryonal kidney 293 T (HEK293T) cells using genome editing to investigate its potential oncogenic functions. Genome editing was performed using CRISPR/Cas9; the proliferation, drug sensitivity, and carcinogenic potential of genome-edited cells were investigated. We also investigated the mechanism underlying the observed phenotypes. Three GBM patients carrying the c.1403A > G mutation were studied to validate the in vitro results. The c.1403A > G mutation led to a splice variant (p.K455_N468delinsN) because of the generation of a 3’-acceptor splice site in exon 10. PDGFRA-mutated HEK293T cells exhibited a higher proliferative activity via PDGFRα and the cyclin-dependent kinase (CDK)4/CDK6-cyclin D1 signaling pathway in a ligand-independent manner. They showed higher sensitivity to multi-kinase, receptor tyrosine kinase, and CDK4/CDK6 inhibitors. Of the three GBM patients studied, two harbored the p.K455_N468delinsN splice variant. The splicing mutation c.1403A > G in PDGFRA is oncogenic in nature. Kinase inhibitors targeting PDGFRα and CDK4/CDK6 signaling should be evaluated for treating GBM patients harboring this mutation.

Abstract 2211: The landscape and implications of kinase-intergenic fusions in a large real-world lung cancer cohort

Abstract Background: Kinase gene fusions are strong driver mutations in neoplasia and have provided fundamental insights into the disease mechanisms that are involved in tumorigenesis. Into the era of next generation sequencing (NGS), numerous studies have described fusion events with breakpoints occurring at two intragenic positions that result in in-frame gene-gene fusions, but fusions that occur with intergenic regions are not uncommon. The clinical significance of such fusions needs to be carefully examined. Methods: We retrospectively reviewed the mutation profiles of over 30 000 lung cancer patients whose tissue and/or plasma samples underwent targeted NGS from June 2016 to July 2019. Clinical data of patients who had kinase-intergenic fusions were retrieved for analysis. RNA sequencing and immunohistochemical (IHC) assays were performed to verify chimeric fusion products on the transcriptional or protein level. Results: A total of 624 kinase-intergenic fusion events were identified in 538 unique lung cancer patients. Approximately 75% (404/538) of the entire cohort were non-small cell lung cancer (NSCLC), and 93% (375/404) of NSCLC were adenocarcinoma. The most frequently identified kinase genes included ALK, RET, ROS1, ERBB2/3, EGFR, FGFR1/2/3, and NTRK1/2/3. Our data showed that most (67%) kinase-intergenic gene rearrangements occurred on the same chromosome and kinase domains remained intact at 3' end. About 3% (19/624) of the kinase-intergenic fusions had one genomic breakpoint located in promoter regions, including 9 events involving ALK, RET, ROS1, EGFR, ERBB2, and FGFR3, which were fused to different gene promoters that may result in changes in kinase gene transcription. Importantly, 371 patients (69%) had concurrent oncogenic driver mutations or intragenic fusions, but the remaining 167 patients (31%) had kinase-intergenic fusions detected solely without other known oncogenic aberrations. Noteworthy, three patients who had ALK-intergenic fusions, but no other known oncogenic aberrations, were confirmed of EML4-ALK chimeric fusion product by RNA sequencing and/or ALK IHC results. Among them, one patient achieved a durable response of 14-month on crizotinib. An additional two patients who had ROS1 intergenic fusions demonstrated clinical benefit of 11 and 19 months from crizotinib, respectively, but the underlying functional fusion products remained to be further determined. Conclusion: This study investigated the role of kinase-intergenic fusions on a large-scale lung cancer population and revealed the potential oncogenic function of kinase-intergenic fusions. Our data also suggested that in addition to DNA sequencing, additional validation testing using RNA and/or protein assay should be performed in intergenic-breakpoint fusion cases to guide optimal treatment. Citation Format: Yutong Ma, Qiuxiang Ou, Xue Wu, Yang Shao. The landscape and implications of kinase-intergenic fusions in a large real-world lung cancer cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2211.

Expression signature of lncRNA APTR in clinicopathology of breast cancer: Its potential oncogenic function in dysregulation of ErbB signaling pathway

A growing amount of evidence has revealed that long noncoding RNAs (lncRNAs) play significant roles in malignancies through different mechanisms especially the competing endogenous RNA (ceRNA). They have also been shown to have the potential diagnostic, prognostic and therapeutic biomarker capacity in oncology research. Recently, lncRNA Alu-mediated p21 transcriptional regulator (APTR) has been proposed as an oncogenic lncRNA in development and clinical outcome of some cancers. However, clinical and molecular importance in breast cancer (BC) is still unclear. The purpose of this study was to examine the APTR expression and its potential roles in BC. The 47 BC tumors and 47 tumor adjacent normal tissues were obtained from the study subjects. Real-time PCR was applied for the analysis of APTR expression in breast tumors compared with paired adjacent normal tissues. Then, we used bioinformatics approach to investigate the potential ceRNA activity of APTR in APTR-microRNAs-mRNAs axes and with focus on ErbB signaling pathway in BC. Our results demonstrated that APTR expression was significantly upregulated in BC tumors compared with the adjacent normal tissues. Besides, APTR over-expression was related to a larger tumors size. Finally, bioinformatics analysis indicated that APTR could influence cell proliferation through dysregulating the oncogenes working in ErbB signaling pathway by sponging some tumor suppressive microRNAs (miRNAs). Current work provided some clues for the involvement of APTR in physiopathology of the breast tumors. However, other aspects of these findings need to be further elucidated by future functional studies.

Dysregulation of cancer genes by recurrent intergenic fusions

BackgroundGene fusions have been studied extensively, as frequent drivers of tumorigenesis as well as potential therapeutic targets. In many well-known cases, breakpoints occur at two intragenic positions, leading to in-frame gene-gene fusions that generate chimeric mRNAs. However, fusions often occur with intergenic breakpoints, and the role of such fusions has not been carefully examined.ResultsWe analyze whole-genome sequencing data from 268 patients to catalog gene-intergenic and intergenic-intergenic fusions and characterize their impact. First, we discover that, in contrast to the common assumption, chimeric oncogenic transcripts—such as those involving ETV4, ERG, RSPO3, and PIK3CA—can be generated by gene-intergenic fusions through splicing of the intervening region. Second, we find that over-expression of an upstream or downstream gene by a fusion-mediated repositioning of a regulatory sequence is much more common than previously suspected, with enhancers sometimes located megabases away. We detect a number of recurrent fusions, such as those involving ANO3, RGS9, FUT5, CHI3L1, OR1D4, and LIPG in breast; IGF2 in colon; ETV1 in prostate; and IGF2BP3 and SIX2 in thyroid cancers.ConclusionOur findings elucidate the potential oncogenic function of intergenic fusions and highlight the wide-ranging consequences of structural rearrangements in cancer genomes.

The long non-coding RNA HCG18 promotes the growth and invasion of colorectal cancer cells through sponging miR-1271 and upregulating MTDH/Wnt/β-catenin.

Long non-coding RNAs (lncRNAs) have recently emerged as key regulators of the occurrence and progression of various human cancers, including colorectal cancer. However, the regulatory mechanism of lncRNAs in the tumorigenesis of colorectal cancer remains poorly understood. In this study, we aimed to elucidate the potential role of lncRNA HCG18 in colorectal cancer. Herein, we found that HCG18 expression was significantly upregulated in colorectal cancer tissues and cell lines. Knockdown of HCG18 significantly inhibited the growth and invasion of colorectal cancer cells, while its overexpression had the opposite effect. Moreover, HCG18 was identified as a sponge of miR-1271. Our results showed that knockdown of HCG18 markedly upregulated miR-1271 expression in colorectal cancer cells. Notably, HCG18 expression was inversely correlated with miR-1271 expression in colorectal cancer specimens. Further investigation revealed that HCG18 contributed to the enhancement of MTDH/Wnt/β-catenin signalling in colorectal cancer cells. The antitumour effect of HCG18 inhibition was significantly reversed by miR-1271 inhibition or MTDH overexpression. Overall, the results of our study demonstrate that HCG18 exerts a potential oncogenic function in colorectal cancer by enhancing MTDH/Wnt/β-catenin signalling via sponging of miR-1271, highlighting the importance of HCG18/miR-1271/ MTDH/Wnt/β-catenin signalling in the progression of colorectal cancer.

SOX12 promotes the growth of multiple myeloma cells by enhancing Wnt/β-catenin signaling

SRY-related high-mobility-group box 12 (SOX12) has currently emerged as a key cancer-related protein in multiple human cancer types. However, little is known about the relevance of SOX12 in multiple myeloma (MM). The current study aimed to investigate the potential role of SOX12 in MM. Our results demonstrated that SOX12 expression was markedly elevated in MM cell lines. A series of cellular assays demonstrated that SOX12 knockdown significantly reduced the proliferation and colony formation, and upregulated cell apoptosis of MM cells. By contrast, SOX12 overexpression promoted the proliferation, colony formation and decreased the apoptosis of MM cells, results that reveal its oncogenic effects. SOX12 regulated β-catenin expression and TCF/LEF transcriptional activity. Moreover, the SOX12-knockdown-mediated antitumor effect in MM cells was significantly reversed by transfecting a β-catenin expression vector. Notably, SOX12 inhibition retarded tumor growth in vivo of a MM-derived mouse xenograft model. In conclusion, our results suggest a potential oncogenic function for SOX12 in MM. Our findings reveal that SOX12 knockdown inhibits the growth of MM cells by downregulating the Wnt/β-catenin signaling pathway, results that imply SOX12 may represent a novel therapeutic target for MM treatment.

MiR-200a-3p promoted the malignant behaviors of ovarian cancer cells through regulating PCDH9.

BackgroundIncreasing evidence has revealed that the aberrant expression of microRNAs (miRNAs) plays vital roles in the development and progression of ovarian cancer. MiR-200a-3p was found to act as an oncogene in a variety of cancers, however, the expression and function of miR-200a-3p in ovarian cancer has not been characterized.Materials and methodsThe expression of miR-200a-3p in ovarian cancer tissues and cell lines was detected by the RT-qPCR. The influence of miR-200a-3p on the growth of ovarian cancer cells was determined with the Cell Counting Kit-8 assay, colony formation and cell invasion assay. The binding of miR-200a-3p with the 3ʹ-untranslated region (UTR) of PDCH9 was detected by luciferase reporter assay. The expression of PCDH9 was investigated by RT-qPCR and Western blot analysis.ResultsmiR-200a-3p was up-regulated in ovarian cancer tissues and cell lines. Highly expressed miR-200a-3p was significantly associated with the tumor size, tumor metastasis and TNM stage. Overexpression of miR-200a-3p markedly promoted the proliferation, colony formation and invasion of ovarian cancer cells. Functional study uncovered that miR-200a-3p bound the 3ʹ-untranslated region (UTR) of PCDH9 and decreased the expression of PCDH9 in ovarian cancer cells. The expression of miR-200a-3p in ovarian cancer tissues was significantly negatively correlated with that of PCDH9. Restored PCDH9 inhibited the promoting effect of miR-200a-3p on the proliferation of ovarian cancer cells.ConclusionOur results suggested the potential oncogenic function of miR-200a-3p via modulating PCDH9 in ovarian cancer.

A comprehensive analysis of core polyadenylation sequences and regulation by microRNAs in a set of cancer predisposition genes

Two core polyadenylation elements (CPE) located in the 3′ untranslated region of eukaryotic pre-mRNAs play an essential role in their processing: the polyadenylation signal (PAS) AAUAAA and the cleavage site (CS), preferentially a CA dinucleotide. Herein, we characterized PAS and CS sequences in a set of cancer predisposition genes (CPGs) and performed an in silico investigation of microRNAs (miRNAs) regulation to identify potential tumor-suppressive and oncogenic miRNAs. NCBI and alternative polyadenylation databases were queried to characterize CPE sequences in 117 CPGs, including 81 and 17 known tumor suppressor genes and oncogenes, respectively. miRNA-mediated regulation analysis was performed using predicted and validated data sources. Based on NCBI analyses, we did not find an established PAS in 21 CPGs, and verified that the majority of PAS already described (74.4%) had the canonical sequence AAUAAA. Interestingly, “AA” dinucleotide was the most common CS (37.5%) associated with this set of genes. Approximately 90% of CPGs exhibited evidence of alternative polyadenylation (more than one functional PAS). Finally, the mir-192 family was significantly overrepresented as regulator of tumor suppressor genes (P < 0.01), which suggests a potential oncogenic function. Overall, this study provides a landscape of CPE in CPGs, which might be useful in development of future molecular analyses covering these frequently neglected regulatory sequences.

MiR‑221‑3p promotes the cell growth of non‑small cell lung cancer by targeting p27.

Emerging evidence suggests the critical function of microRNAs in regulating the growth of cancer cells. In the present study, it was demonstrated that miR-221-3p was overexpressed in non-small cell lung cancer (NSCLC) tissues and cell lines compared with that noted in the normal controls. Downregulation of miR-221-3p suppressed the proliferation, colony formation and invasion of NSCLC cells. To further understand the molecular mechanisms underlying the potential oncogenic function of miR-221-3p in NSCLC, the downstream targets of miR-221-3p were predicted using bioinformatic databases. The prediction suggested the cell cycle regulator p27 as one of the targets of miR-221-3p. Molecular experiments showed that miR-221-3p was able to bind with the 3′-untranslated region (UTR) of p27 and decreased the expression of p27 in NSCLC cells. Consistent with the suppressive role of p27 in controlling cell cycle progression, overexpression of miR-221-3p decreased the expression of p27 and promoted cell cycle progression from G1 to S phase. Collectively, our findings identified miR-221-3p as a novel regulator of NSCLC cell growth via modulating the expression of p27.

Long non-coding RNA UCA1 promoted the growth of adrenocortical cancer cells via modulating the miR-298-CDK6 axis

Adrenocortical cancer (ACC) is an aggressive malignancy with no available effective treatments; therefore, exploring the molecular mechanisms involved in the initiation and progression of ACC is quite important. Here, we found that the long noncoding RNA urothelial carcinoma-associated 1 (UCA1) was highly expressed in ACC tissues and closely associated with the TNM stage and metastasis of ACC patients. Overexpression of UCA1 significantly promoted the proliferation and suppressed the apoptosis of ACC cells. Mechanism study showed that UCA1 acted as sponge of miR-298 and decreased the expression abundance of miR-298 in ACC cells. Further investigation identified that miR-298 bound the 3’-UTR of the cyclin-dependent kinase 6 (CDK6) and inhibited the expression of CDK6. Consistently, ectopic expressed UCA1 suppressed miR-298 and up-regulated the expression of CDK6, which promoted the cell cycle progression of ACC cells. Taken together, our results identified the potential oncogenic function of UCA1 in ACC by regulating the miR-298-CDK6 axis.

SRPK1 facilitates tumor cell growth via modulating the small nucleolar RNA expression in gastric cancer.

Serine-arginine protein kinase 1 (SRPK1) is the main regulator in alternative splicing by phosphorylating splicing factors rich in serine/arginine repeats. Its overexpression has been found in multiple cancer types and contributes to cancer development. Here we report the role of SRPK1 and underlying mechanism in gastric cancer (GC) cell growth. We found that SRPK1 was frequently upregulated in GC samples compared with their adjacent corresponding normal tissues by immunohistochemistry and western blot analysis. Knockdown of SRPK1 in GC cells suppressed cell growth in cell viability assays, colony formation assays and nude mice xenograft model, whereas overexpression of SRPK1 promotes opposite phenotypes in these assays. By a complementary DNA microarray analysis, we found that SRPK1 knockdown had significant inhibitory effects on a majority of small nucleolar RNAs expression. Among them, snoRA42, snoRA74A, and snoRD10 were selected for further functional experiments. Cell growth curves on a plate and in soft agar indicated that the three snoRNAs play potential oncogenic function in GC. In addition, SRPK1 could co-immunoprecipitated with NCL, a nucleolar phosphoprotein involved in the synthesis and maturation of ribosomes. These results suggested that SRPK1 contributes to GC development by a new possible mechanism involving snoRNAs mediated signaling.

Anaplastic lymphoma kinase fusions: Roles in cancer and therapeutic perspectives.

Receptor tyrosine kinase (RTK) anaplastic lymphoma kinase (ALK) serves a crucial role in brain development. ALK is located on the short arm of chromosome 2 (2p23) and exchange of chromosomal segments with other genes, including nucleophosmin (NPM), echinoderm microtubule-associated protein-like 4 (EML4) and Trk-fused gene (TFG), readily occurs. Such chromosomal translocation results in the formation of chimeric X-ALK fusion oncoproteins, which possess potential oncogenic functions due to constitutive activation of ALK kinase. These proteins contribute to the pathogenesis of various hematological malignancies and solid tumors, including lymphoma, lung cancer, inflammatory myofibroblastic tumors (IMTs), Spitz tumors, renal carcinoma, thyroid cancer, digestive tract cancer, breast cancer, leukemia and ovarian carcinoma. Targeting of ALK fusion oncoproteins exclusively, or in combination with ALK kinase inhibitors including crizotinib, is the most common therapeutic strategy. As is often the case for small-molecule tyrosine kinase inhibitors (TKIs), drug resistance eventually develops via an adaptive secondary mutation in the ALK fusion oncogene, or through engagement of alternative signaling mechanisms. The updated mechanisms of a variety of ALK fusions in tumorigenesis, proliferation and metastasis, in addition to targeted therapies are discussed below.

The long noncoding RNA NORAD promotes the growth of gastric cancer cells by sponging miR-608

Dysfunction of long non-coding RNAs (lncRNAs) has been suggested to play pivotal roles in the initiation and progression of human cancers. The noncoding RNA activated by DNA damage (NORAD) is a recently identified, highly conserved lncRNA that is essential for the mitotic cell division. Recent studies demonstrated the potential oncogenic function of NORAD in bladder cancer and colon cancer, however, the role and clinical value of NORAD have not been illustrated in gastric cancer. Here, we found that NORAD was highly expressed in gastric cancer tissues and cell lines. Overexpression of NORAD was significantly correlated with the worse prognosis of the gastric cancer patients. Down-regulation of NORAD suppressed the proliferation and migration of gastric cancer cells. Mechanistically, NORAD acted as a competitive endogenous RNA (ceRNA), which sponged miR-608 and suppressed the expression of miR-608 in gastric cancer cells. Further experiments demonstrated that miR-608 targeted the forkhead box O6 (FOXO6) and negatively regulated the expression of FOXO6. Consistent with the inhibitory effect of NORAD on miR-608, overexpression of NORAD enhanced the level of FOXO6 in gastric cancer cells. Overexpression of FOXO6 attenuated the inhibitory effect of miR-608 on the gastric cancer cell growth. Collectively, our results demonstrated that NORAD promoted the growth of gastric cancer cells via modulating the miR-608/FOXO6 pathway.

Abstract 1357: Functional characterization of FANCD2 in esophageal squamous cell carcinoma

Abstract Introduction: Esophageal squamous cell carcinoma (ESCC) has an especially high incidence in Northern China, where there is evidence for a significant familial association. We performed targeted next-generation sequencing (NGS) analysis on familial ESCC germline samples compared to non-cancer controls from the same high-risk region and compiled a list of candidate cancer predisposition genes. Interestingly, genes related to the Fanconi Anemia (FA) - BRCA pathway are enriched in the list. Among these FA-BRCA genes, Fanconi anemia complementation group D2 (FANCD2) was one of the top candidates, as it also had a high frequency of somatic mutations in ESCC tumor specimens. Therefore, we aim to characterize the role of FANCD2 in tumor development and explore its translational value. Methods: We knocked out the FANCD2 gene in ESCC cell lines using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) technique to evaluate its potential oncogenic function in ESCC. Cell proliferation was measured by a MTT 2D clonogenic assay in vitro. Subcutaneous injection of the FANCD2 knockout ESCC cells into BALB/c-nude mice in vivo was performed to assess its functional impact on tumorigenesis. The single cell gel electrophoresis/comet assay was used to investigate the genome stability. Results: The FANCD2 knockout efficiency was confirmed by western blotting. Surprisingly, in vitro functional analyses showed that ESCC cells with FANCD2 knockout survive, with a greatly reduced growth rate and colony-forming ability. Consistent with the in vitro data, ESCC cells with FANCD2 knockout form significantly smaller subcutaneous tumors in nude mice. By applying the comet assay to examine the genome integrity, ESCC cells with FANCD2 knockout show significantly greater damage to the genome. Conclusion: These results suggest that FANCD2 plays an important role in supporting ESCC tumor growth. We attribute this to its core function in DNA repair ability and genome integrity maintenance. Acknowledgement: We acknowledge the grant support from the Hong Kong Research Grants Council Collaborative Research Fund (C7031.15G to M.L.L.). Citation Format: Lisa Chan Lei, Valen Zhuoyou Yu, Lvwen Ning, Josephine Mun-Yee Ko, Li Dong Wang, Maria Li Lung. Functional characterization of FANCD2 in esophageal squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1357.