Over-expression and amplification of the c-myc gene in human urothelial carcinoma

Biological significance of MYC and CEBPD coamplification in urothelial carcinoma: Multilayered genomic, transcriptional and posttranscriptional positive feedback loops enhance oncogenic glycolysis

BACKGROUND AND PURPOSE

The aim of this study is to decipher the underlying mechanisms of CCAAT/enhancer-binding protein delta (CEBPD)-enhanced glycolysis as well as the biological significance of CEBPD and MYC coamplification in urothelial carcinoma (UC).

METHODS

In vitro analyses were conducted to examine the effects of altered CEBPD or MYC expression on UC cells. The in vivo effects of CEBPD overexpression in a high-glucose environment on tumour growth were investigated in xenografted induced diabetic severe combined immunodeficiency/beige mice. Data mining was used to cross-validate the associations between CEBPD and MYC copy number and transcriptional expression, quantitative reverse transcription-polymerase chain reaction, immunohistochemistry, chromogenic in situ hybridization, and in situ hybridization targeting microRNA were performed on 635 UC patient samples and xenograft samples. UC patient survival in relation to diabetes was validated by using the National Health Insurance Research Database.

RESULTS

CEBPD and MYC coamplification (29.6%) occurred at a high frequency, MYC expression promoted chromosomal instability, facilitating CEBPD copy number gain and expression. CEBPD promoted glucose uptake and lactate production by upregulating SLC2A1 and HK2, leading to mitochondrial fission, increased extracellular acidification rate and decreased oxygen consumption rate to fuel cell growth. CEBPD upregulated HK2 expression through multiple regulation pathways including MYC stabilization, suppression of FBXW7 transactivation and MYC-independent transcriptional suppression of hsa-miR-429. Clinical and xenografted experiments confirmed the growth advantage of CEBPD in relation to glucose metabolic dysregulation and the significant correlations between the expression of these genes.

CONCLUSIONS

We confirmed that CEBPD has an oncogenic role in UC by activating AKT signalling and initiating metabolic reprogramming from mitochondrial oxidative phosphorylation to glycolysis to satisfy glucose addiction. These novel CEBPD- and MYC-centric multilayered positive feedback loops enhance cancer growth that could complement theranostic approaches.

RRM2B Is Frequently Amplified Across Multiple Tumor Types: Implications for DNA Repair, Cellular Survival, and Cancer Therapy

RRM2B plays a crucial role in DNA replication, repair and oxidative stress. While germline RRM2B mutations have been implicated in mitochondrial disorders, its relevance to cancer has not been established. Here, using TCGA studies, we investigated RRM2B alterations in cancer. We found that RRM2B is highly amplified in multiple tumor types, particularly in MYC-amplified tumors, and is associated with increased RRM2B mRNA expression. We also observed that the chromosomal region 8q22.3–8q24, is amplified in multiple tumors, and includes RRM2B, MYC along with several other cancer-associated genes. An analysis of genes within this 8q-amplicon showed that cancers that have both RRM2B-amplified along with MYC have a distinct pattern of amplification compared to cancers that are unaltered or those that have amplifications in RRM2B or MYC only. Investigation of curated biological interactions revealed that gene products of the amplified 8q22.3–8q24 region have important roles in DNA repair, DNA damage response, oxygen sensing, and apoptosis pathways and interact functionally. Notably, RRM2B-amplified cancers are characterized by mutation signatures of defective DNA repair and oxidative stress, and at least RRM2B-amplified breast cancers are associated with poor clinical outcome. These data suggest alterations in RR2MB and possibly the interacting 8q-proteins could have a profound effect on regulatory pathways such as DNA repair and cellular survival, highlighting therapeutic opportunities in these cancers.

Boosting bladder cancer treatment by intravesical nitazoxanide and bacillus calmette-guérin association

PURPOSE

Nitazoxanide (NTZ) has shown a promising antitumoral effect, the current study compared the anti-neoplastic effects of intravesical NTZ and BCG plus NTZ in NMIBC animal model.

METHODS

30 rats, Fisher 344 were instilled with 4 intravesical doses of 1.5 mg/kg of N-methyl-N-nitrosourea (MNU) every 15 days for BC induction. The animals were divided into 3 groups (Group BCG 10⁶ UFC - 1 mg of BCG; Group NTZ - 300 mg/kg of NTZ; Group NTZ + BCG - simultaneous treatment of BCG and NTZ) and received weekly intravesical treatment for 6 consecutive weeks. Animals were submitted to ultrasound imaging and euthanasia, their bladders were collected and histopathological, immunohistochemical tests (ki67 e c-Myc) and Western Blotting (PI3K, mTOR, and p-4E-BP) were performed.

RESULTS

Histopathological tests showed 66.67%, 62.5% and 37.5% incidence of BC in animals treated with BCG, NTZ, and NTZ + BCG, respectively. Nuclear positivity for ki-67 in BC animals were 12.4% (IC 10.1-14.6%), 13.2% (IC 10.5-15.9%) and 8.8% (IC 6.0-11.6%) in BCG, NTZ and NTZ + BCG group, respectively (p = 0.063). Between animals with carcinoma, c-Myc strong positive was 40.10% in NTZ, 32.2% in BCG and 19.90% in the NTZ + BCG group (p < 0.001). Blotting has shown mTOR (p = 0.0473) and PI3K inhibition (p = 0.0349) in the presence of BCG, added to 4-EBP inhibition in the presence of NTZ (p = 0.0004).

CONCLUSIONS

Results show the possible synergy between the gold standard BC treatment BCG and NTZ, in which multiple targets inhibition such as c-Myc and downstream mTOR, p-4E-BP and PI3K might play a role.

The Impact of p53 on Aristolochic Acid I-Induced Gene Expression In Vivo

Exposure to aristolochic acid (AA) is linked to kidney disease and urothelial cancer in humans. The major carcinogenic component of the AA plant extract is aristolochic acid I (AAI). The tumour suppressor p53 is frequently mutated in AA-induced tumours. We previously showed that p53 protects from AAI-induced renal proximal tubular injury, but the underlying mechanism(s) involved remain to be further explored. In the present study, we investigated the impact of p53 on AAI-induced gene expression by treating Trp53(+/+), Trp53(+/-), and Trp53(-/-) mice with 3.5 mg/kg body weight (bw) AAI daily for six days. The Clariom™ S Assay microarray was used to elucidate gene expression profiles in mouse kidneys after AAI treatment. Analyses in Qlucore Omics Explorer showed that gene expression in AAI-exposed kidneys is treatment-dependent. However, gene expression profiles did not segregate in a clear-cut manner according to Trp53 genotype, hence further investigations were performed by pathway analysis with MetaCore™. Several pathways were significantly altered to varying degrees for AAI-exposed kidneys. Apoptotic pathways were modulated in Trp53(+/+) kidneys; whereas oncogenic and pro-survival pathways were significantly altered for Trp53(+/-) and Trp53(-/-) kidneys, respectively. Alterations of biological processes by AAI in mouse kidneys could explain the mechanisms by which p53 protects from or p53 loss drives AAI-induced renal injury in vivo.

CARLo-7-A plausible biomarker for bladder cancer

Cancer is defined as undifferentiated and unchecked growth of cells damaging the surrounding tissue. Cancers manifest altered gene expression. Gene expression is regulated by a diverse array of non-protein-coding RNA. Aberrant expression of long non-coding RNAs (lncRNAs) has been recently found to have functional consequences in cancers. In the current study, we report CARLo-7 as the only bladder cancer-specific lncRNA from the CARLos cluster. The expression of this lncRNA correlates with bladder cancer grade. We propose that CARLo-7 has an oncogenic potential and might be regulator of cell proliferation. Furthermore, by comparison the expression of proto-oncogene MYC, which is the only well-annotated gene close to the cancer - associated linkage disequilibrium blocks of this region, does not show a pronounced change in expression between the low- and high-grade tumours. Our results indicate that CARlo-7 can act as a prognostic marker for bladder cancer.

MicroRNA Dysregulation and Non-Muscle-Invasive Bladder Cancer Prognosis

BACKGROUND

The high rate of non-muscle-invasive bladder cancer recurrence is a major challenge in patient management. miRNAs functionally regulate tumor cell proliferation and invasion, and have strong potential as biomarkers because they are robust to degradation. The objective of this project was to identify reproducible prognostic miRNAs in resected non-muscle-invasive bladder tumor tissue that are predictive of the recurrent tumor phenotype.

METHODS

We utilized patients diagnosed with primary non-muscle-invasive bladder cancer in three independent cohorts for a biomarker discovery/validation approach. Baseline tumor tissue from patients with the clinically challenging, non-muscle-invasive primary low stage (Ta), high grade, and T1 tumors (tumors extending into the lamina propria) comprised the discovery cohort (n = 38). We isolated the tumor tissue RNA and assessed a panel of approximately 800 miRNAs.

RESULTS

miR-26b-5p was the top-ranking prognostic tumor tissue miRNA, with a time-to-recurrence HR 0.043 for levels above versus below median, (P _adj = 0.0003). miR-26b-5p was related to a dose-response reduction in tumor recurrence, and levels above the median were also associated with reduced time-to-progression (P _adj = 0.02). We used two independent longitudinal cohorts that included both low-grade and high-grade Ta and T1 tumors for validation and found a consistent relationship between miR-26b-5p and recurrence and progression.

CONCLUSIONS

Our results suggest that miR-26b-5p levels may be prognostic for non-muscle-invasive bladder cancer recurrence, and can feasibly be assessed in baseline tumor tissue from a wide variety of clinical settings.

IMPACT

Early identification of those non-muscle-invasive bladder tumor patients with refractory phenotypes would enable individualized treatment and surveillance.

ASP5878, a selective FGFR inhibitor, to treat FGFR3-dependent urothelial cancer with or without chemoresistance

FGF/FGFR gene aberrations such as amplification, mutation and fusion are associated with many types of human cancers including urothelial cancer. FGFR kinase inhibitors are expected to be a targeted therapy for urothelial cancer harboring FGFR3 gene alternations. ASP5878, a selective inhibitor of FGFR1, 2, 3 and 4 under clinical investigation, selectively inhibited cell proliferation of urothelial cancer cell lines harboring FGFR3 point mutation or fusion (UM-UC-14, RT-112, RT4 and SW 780) among 23 urothelial cancer cell lines. Furthermore, ASP5878 inhibited cell proliferation of adriamycin-resistant UM-UC-14 cell line harboring MDR1 overexpression and gemcitabine-resistant RT-112 cell line. The protein expression of c-MYC, an oncoprotein, in gemcitabine-resistant RT-112 cell line was higher than that in RT-112 parental cell line and ASP5878 decreased the c-MYC expression in both RT-112 parental and gemcitabine-resistant RT-112 cell lines. Once-daily oral administration of ASP5878 exerted potent antitumor activities in UM-UC-14, RT-112 and gemcitabine-resistant RT-112 xenograft models without affecting body weight. These findings suggest that ASP5878 has the potential to be an oral targeted therapy against urothelial cancer harboring FGFR3 fusion or FGFR3 point mutation after the acquisition of gemcitabine- or adriamycin-resistance.

Distribution of the c-MYC gene product in colorectal neoplasia

AIMS

Recent attempts to study MYC distribution in human samples have been confounded by a lack of agreement in immunohistochemical staining between antibodies targeting the N-terminus and those targeting the C-terminus of the MYC protein. The aim of this study was to use a novel in-situ hybridization (ISH) approach to detect MYC mRNA in clinically relevant samples, and thereby determine the reliability of MYC-targeting antibodies.

METHODS AND RESULTS

We performed immunohistochemistry on human formalin-fixed paraffin embedded normal colon (n = 15), hyperplastic polyp (n = 4) and neoplastic colon samples (n = 55), using the N-terminally directed antibody Y69, and the C-terminally directed antibody 9E10. The MYC protein distributions were then compared with the location of MYC mRNA, determined by ISH. We found that the localization of MYC mRNA correlated well with the protein distribution determined with the N-terminally directed antibody Y69, and was also associated with expression of the proliferation marker Ki67. The protein distribution determined with the C-terminally directed antibody 9E10 was not always associated with MYC mRNA, Y69, or Ki67, and indeed often showed a reciprocal pattern of expression, with staining being strongest in non-proliferating cells.

CONCLUSIONS

The observed discrepancy between the staining patterns suggests that the significance of 9E10 in immunohistochemical staining is currently uncertain, and therefore should be interpreted with caution.

Bladder cancer: a simple model becomes complex

Bladder cancer is one of the most frequent malignancies in developed countries and it is also characterized by a high number of recurrences. Despite this, several authors in the past reported that only two altered molecular pathways may genetically explain all cases of bladder cancer: one involving the FGFR3 gene, and the other involving the TP53 gene. Mutations in any of these two genes are usually predictive of the malignancy final outcome. This cancer may also be further classified as low-grade tumors, which is always papillary and in most cases superficial, and high-grade tumors, not necessarily papillary and often invasive. This simple way of considering this pathology has strongly changed in the last few years, with the development of genome-wide studies on expression profiling and the discovery of small non-coding RNA affecting gene expression. An easy search in the OMIM (On-line Mendelian Inheritance in Man) database using "bladder cancer" as a query reveals that genes in some way connected to this pathology are approximately 150, and some authors report that altered gene expression (up- or down-regulation) in this disease may involve up to 500 coding sequences for low-grade tumors and up to 2300 for high-grade tumors. In many clinical cases, mutations inside the coding sequences of the above mentioned two genes were not found, but their expression changed; this indicates that also epigenetic modifications may play an important role in its development. Indeed, several reports were published about genome-wide methylation in these neoplastic tissues, and an increasing number of small non-coding RNA are either up- or down-regulated in bladder cancer, indicating that impaired gene expression may also pass through these metabolic pathways. Taken together, these data reveal that bladder cancer is far to be considered a simple model of malignancy. In the present review, we summarize recent progress in the genome-wide analysis of bladder cancer, and analyse non-genetic, genetic and epigenetic factors causing extensive gene mis-regulation in malignant cells.

CIP2A is a predictor of survival and a novel therapeutic target in bladder urothelial cell carcinoma

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a recently identified human oncoprotein that stabilizes the c-MYC protein. Herein, we aimed to investigate its expression pattern, clinical significance, and biological function in urothelial cell carcinoma (UCC) of the bladder. CIP2A expression was examined in 20 fresh bladder UCC tissues and paired adjacent normal bladder tissues by RT-PCR and Western blot. Immunohistochemistry for CIP2A was performed on additional 117 bladder UCC tissues. The clinical significance of CIP2A expression was analyzed. CIP2A downregulation was performed in bladder UCC cell line T24 with high abundance of CIP2A, and the effects of CIP2A silencing on cell proliferation, migration, invasion in vitro, and tumor growth in vivo were evaluated. We found that CIP2A expression was upregulated in bladder UCC tissues relative to adjacent normal bladder tissues. Clinicopathological analysis showed that CIP2A expression was significantly associated with tumor stage (P = 0.004), histological grade (P = 0.007), and lymph node status (P = 0.001). The Kaplan-Meier survival curves revealed that CIP2A expression was associated with poor prognosis in bladder UCC patients (log-rank value = 14.704, P < 0.001). CIP2A expression was an independent prognostic marker of overall patient survival in a multivariate analysis (P = 0.015). Knockdown of the CIP2A expression reduced cell proliferation, anchorage-independent growth, migration, invasion, and tumor growth in xenograft model mice. Our findings suggest that CIP2A is an independent predictor of poor prognosis of bladder UCC patients, and inhibition of its expression might be of therapeutic significance.

Gene expression profiling of the synergy of 5-aza-2'-deoxycytidine and paclitaxel against renal cell carcinoma

Background

Renal cell carcinoma (RCC) is one of the most common kidney cancers and is highly resistant to chemotherapy. We previously demonstrated that 5-aza-2^′-deoxycytidine (DAC) could significantly increase the susceptibility of renal cell carcinoma (RCC) cells to paclitaxel (PTX) treatment in vitro, and showed the synergy of DAC and PTX against RCC. The purpose of this study is to investigated the gene transcriptional alteration and investigate possible molecular mechanism and pathways implicated in the synergy of DAC and PTX against RCC.

Methods

cDNA microarray was performed and coupled with real-time PCR to identify critical genes in the synergistic mechanism of both agents against RCC cells. Various patterns of gene expression were observed by cluster analysis. IPA software was used to analyze possible biological pathways and to explore the inter-relationships between interesting network genes.

Results

We found that lymphoid enhancer-binding factor 1 (LEF1), transforming growth factor β-induced (TGFBI), C-X-C motif ligand 5 (CXCL5) and myelocytomatosis viral related oncogene (c-myc) may play a pivotal role in the synergy of DAC and PTX. The PI3K/Akt pathway and other pathways associated with cyclins, DNA replication and cell cycle/mitotic regulation were also associated with the synergy of DAC and PTX against RCC.

Conclusion

The activation of PI3K/Akt-LEF1/β-catenin pathway could be suppressed synergistically by two agents and that PI3K/Akt-LEF1/β-catenin pathway is participated in the synergy of two agents.

Gene expression changes induced by the human carcinogen aristolochic acid I in renal and hepatic tissue of mice

Aristolochic acid (AA) is the causative agent of urothelial tumors associated with AA nephropathy and is also implicated in the development of Balkan endemic nephropathy-associated urothelial tumors. These tumors contain AA-characteristic TP53 mutations. We examined gene expression changes in Hupki (human TP53 knock-in) mice after treatment with aristolochic acid I (AAI) by gavage (5 mg/kg body weight). After 3, 12 and 21 days of treatment gene expression profiles were investigated using Agilent Whole Mouse 44K Genome Oligo Array. Expression profiles were significantly altered by AAI treatment in both target (kidney) and nontarget (liver) tissue. Renal pathology and DNA adduct analysis confirmed kidney as the target tissue of AAI-induced toxicity. Gene ontology for functional analysis revealed that processes related to apoptosis, cell cycle, stress response, immune system, inflammatory response and kidney development were altered in kidney. Canonical pathway analysis indicated Nfκb, aryl hydrocarbon receptor, Tp53 and cell cycle signaling as the most important pathways modulated in kidney. Expression of Nfκb1 and other Nfκb-target genes was confirmed by quantitative real-time PCR (qRT-PCR) and was consistent with the induction of Nfκb1 protein. Myc oncogene, frequently overexpressed in urothelial tumors, was upregulated by AAI on the microarrays and confirmed by qRT-PCR and protein induction. Collectively we found that microarray gene expression analysis is a useful tool to define tissue-specific responses in AAI-induced toxicity. Several genes identified such as TP53, Rb1, Mdm2, Cdkn2a and Myc are frequently affected in human urothelial cancer, and may be valuable prognostic markers in future clinical studies.

BAMBI gene is epigenetically silenced in subset of high-grade bladder cancer

The bone morphogenetic protein (BMP) and activin membrane-bound inhibitor (BAMBI) is a transmembrane TGFRI/BMPRI-related pseudoreceptor, antagonizes transforming growth factor (TGF)-beta/BMP signaling by inhibiting the formation of functional authentic receptor complexes (TGFRI/BMPRI and TGFRII/BMPRII). On the assumption that BAMBI gene expression is epigenetically altered during human bladder cancer progression, we screened the expression of BAMBI protein by immunohistochemistry and the methylation status of the BAMBI promoter. In the normal or reactive urothelium, BAMBI expression was mostly overlapped with that of BMPRI, and a similar colocalization pattern was noted in low-grade papillary cancers. In high-grade and invasive cancers, however, mainly two reciprocal immunohistochemical expression patterns were observed: BAMBI-low/BMPRI-high, and BAMBI-high/BMPRI-low, indicating that BAMBI expression is controlled such that it does not interfere with the responsiveness of high-grade cancer cells to TGF-beta/BMP signaling. Moreover, methylation of the BAMBI gene correlated significantly with negative BAMBI expression in bladder tumors. Although BAMBI overexpression significantly increased the number of apoptotic cells in T24 line, knock-down small interfering RNA showed no remarkable change. Cell motility assay revealed that on treatment with either TGF-beta1 or BMP2, T24 and HTB9 lines showed a marked increase in the number of migrated cells which, however, decreased significantly through the forced expression of BAMBI. Since certain subsets of aggressive tumors often promote cell motility, invasion and survival by inducing epithelial-to-mesenchymal transition through TGF-beta/BMP in an autocrine and paracrine manner, hypermethylation of the BAMBI gene promoter that leads to BAMBI gene suppression may be one of the epigenetic events affecting the invasiveness or aggressiveness of bladder cancers.

The FUSE binding proteins FBP1 and FBP3 are potential c-myc regulators in renal, but not in prostate and bladder cancer

Background

The three far-upstream element (FUSE) binding proteins (FBP1, FBP2, and FBP3) belong to an ancient family of single-stranded DNA binding proteins which are required for proper regulation of the c-myc proto-oncogene. Whereas it is known that c-myc alterations play a completely different role in various carcinomas of the urogenital tract, the relevance of FBPs is unclear.

Methods

FBP1, FBP3 and c-myc expression was studied in 105 renal cell, 95 prostate and 112 urinary bladder carcinomas by immunohistochemistry using tissue microarrays.

Results

High rates of FBP1 and FBP3 expression were observed in all cancer types. There was a concomitant up-regulation of FBP1 and FBP3 in renal cell and prostate carcinomas (p < 0.001 both). C-myc expression was detectable in 21% of prostate, 30% of renal and 34% of urothelial carcinomas. Interestingly, strong FBP1 and FBP3 expression was associated with c-myc up-regulation in clear cell renal cell carcinomas (p < 0.001 and 0.09 resp.), but not in bladder or prostate cancer.

Conclusion

The correlation between FBP1/FBP3, c-myc and high proliferation rate in renal cell carcinoma provides strong in vivo support for the suggested role of FBP1 and FBP3 as activators of c-myc. The frequent up-regulation of FBP1 and FBP3 in urothelial and prostate carcinoma suggests that FBPs also have an important function in gene regulation of these tumors.

Development of human gene reporter cell lines using rAAV mediated homologous recombination

Understanding mechanisms of gene regulation has broad therapeutic implications for human disease. Here we describe a novel method for generating human cell lines that serve as reporters of transcriptional activity. This method exploits the ability of recombinant adeno-associated virus to mediate the insertion of exogenous DNA sequences into specific genomic loci through homologous recombination. To overcome the severe size limitation of the rAAV for carrying exogenous DNA, an enhanced green fluorescent protein (EGFP)-Luciferase fusion gene was used as both a selectable marker and gene expression reporter. EGFP was used for selection of correctly targeted alleles by taking advantage of known regulatory conditions that activate transcription of specific genes. Using this method, we describe the generation of primary human fibroblasts that express EGFP-Luciferase under the control of the c-Myc oncogene.

Understanding urothelial carcinoma through cancer pathways

Urothelial carcinoma (UC), the common histological subtype of bladder cancer, presents as a papillary tumor or as an invasive, often lethal form. To study UC molecular biology, candidate gene and genome-wide approaches have been followed. Here, it is argued that a 'cancer pathway' perspective is useful to integrate findings from both approaches. According to this view, papillary cancers typically exhibit activation of the MAPK pathway, as a consequence of oncogenic mutations in FGFR3 or HRAS, with increased Cyclin D1 expression. In contrast, invasive UC are characterized by severe disturbances in proximate cell cycle regulators, e.g. RB1 and CDKN2A/p16(INK4A), which decrease dependency on mitogenic signaling. In addition, these disturbances permit, promote and are in turn exacerbated by chromosomal instability, which is further enhanced by loss of TP53 function. In another vicious cycle, defective cell cycle regulation interacts with DNA methylation alterations. The transition toward invasive UC may require concomitant and interacting defects in cell cycle regulation and the control of genomic stability. Intriguingly, neither canonical WNT/beta-Catenin nor hedgehog signaling appear to play major roles in UC. This may reflect its origin from more differentiated urothelial cells possessing a high regenerative potential rather than a stem cell population.

Genetic alterations in urothelial bladder carcinoma: an updated review

New oncogenes and tumor suppressor genes that play an important role in the pathogenesis of urothelial bladder carcinoma have been discovered. The objectives of this review were to summarize the most important oncogenes and tumor suppressor genes involved in urothelial carcinoma and to address their role in pathogenesis, their prognostic value, and their potential use as therapeutic targets. The collected data led the authors to propose a common pathway in which the fibroblastic growth factor receptor 3 (FGFR3) mutation seems to be the earliest genetic abnormality responsible for the transformation from normal tissue to atypia and dysplasia. Three different progression pathways were proposed: The first operative pathway is from dysplasia to superficial papillary pathologic Ta (pTa) tumors to pT1 tumors and, ultimately, to pT2 tumors with FGFR3 and tuberous sclerosis complex 1 (TSC1) the responsible genes. The second major operative pathway is from dysplasia, to carcinoma in situ, and to solid pT1 and pT2 tumors. The third pathway of progression is from dysplasia to papillary T1 and pT2 tumors. The genes involved in the last 2 pathways are the p53, serine threonine protein kinase 15 (STK15), triple-function domain (TRIO), fragile histidine triad (FHIT), p63 genes; and alterations of 20q and 5p, alterations of adhesions, angiogenesis, and matrix-remodeling gene products also are involved. Finally, murine leukemia viral oncogene homologue 1 (RAF1) and CD9 are involved in the progression from papillary pT1 tumors to pT2 tumors.

High-throughput tissue microarray analysis ofCMYC amplificationin urinary bladder cancer

Alterations of chromosome 8, preferentially deletions of 8p and gains of 8q, belong to the most frequent cytogenetic changes in bladder cancer. CMYC on 8q24 is a candidate oncogene in this region. Little is known about the clinical significance of CMYC copy number changes in urinary bladder cancer because its frequency is low and a limited numbers of tumors were analyzed so far. To investigate the impact of CMYC alterations on tumor progression and patient prognosis in bladder cancer, we applied FISH to a tissue microarray containing 2317 bladder cancer samples. Presence of CMYC copy number increase was associated with advanced stage and high grade. CMYC amplifications were seen in 3 of 467 pTa (0.6%), 10 of 247 pT1 (4%) and 11 of 201 pT2-4 urothelial carcinomas (5.5%; p < 0.0001), as well as in 1 of 123 G1 (0.8%), 8 of 470 G2 (1.7%) and 17 of 365 G3 urothelial carcinomas (4.7%; p < 0.0001). CMYC gains were present in 49 of 467 pTa (10.5%), 39 of 247 pT1 (15.8%) and 43 of 201 pT2-4 urothelial carcinoma (21.4%; p < 0.0001), as well as in 7 of 123 G1 (5.7%), 56 of 470 G2 (11.9%) and 72 of 365 G3 urothelial carcinomas (19.7%; p < 0.0001). CMYC copy number changes were unrelated to prognosis of bladder cancer patients. We conclude that alterations of the CMYC gene, including copy number gains and amplifications, are linked to genetically unstable bladder cancers that are characterized by a high histologic grade and/or invasive growth. Patient prognosis was not affected by CMYC gene copy number changes.

The c-myc activation in cervical carcinomas and HPV 16 infections

Despite the prominent role for Human Papillomavirus (HPV) infection in the development of genital cancer, other genetic or environmental co-factors have also been involved. Studies of c-myc activation in cervical carcinomas have reported that gene over-expression (mainly gene amplification) are common in cervical squamous cell carcinomas and may correlate with the biologic behavior of the neoplasm. Using PCR based technology, DNAs from 79 normal cervical samples and 225 abnormal cervical tissue scrapes were analyzed for HPV detection and typing and for c-myc gene amplification. Significant differences were found between the different cyto/histology groups (P<0.0001) and also with HPV high-risk infected samples (P<0.0002). In this sense, we showed that the average c-myc copy number increased according to the histological grade of the lesion (OR=6.3, CI=2.1-18.8). Also, the results showed that the infection with HPV 16 was tightly associated with c-myc amplification (OR=10.6, CI=3.1-36). These results could indicate that oncogene amplification take place in pre-invasive stages of cervical disease and could cooperate not only in tumor progression but also in cell transformation. Moreover, the results strongly associate the c-myc gene amplification to the infection with the oncogenic HPV 16, showing that the pattern of virus infection and oncogene activation could be specific for different viral genotypes.

Hyperexpression of locus C genes in the HOX network is strongly associated in vivo with human bladder transitional cell carcinomas

Bladder carcinogenesis remains unclear despite the identification of chemical, environmental and genetic factors. It has recently been reported that the chromosomal region 12q13-q15, containing crucial cancer genes such as MDM2, CDK4 and GLI, is amplified in bladder cancer. In the same region are also located the genes of the locus HOX C, flanked by keratin genes whose protein product may be a prognostic marker of bladder cancer. The HOX genes constitute a network of transcription factors controlling embryonal development and play an important role in crucial adult eukaryotic cell functions. The molecular organization of this 39-gene network is unique in the genome and probably acts by regulating phenotypical cell identity. We have analysed the expression of the whole HOX gene network in pairs of normal-tumour bladder and in tumoral biopsies. Comparison between normal urothelium and bladder tumour has identified dramatic variations of expression in a block of three genes (HOX C4, HOX C5 and HOX C6) localized in the HOX C locus on the chromosome 12q13 and in the paralogous group 11 HOX genes, involved during normal development in the formation of the urogenital system. These data suggest a key involvement of the HOX gene network, and especially the locus C, in bladder cancer.

E-cadherin involved in inactivation of WNT/beta-catenin signalling in urothelial carcinoma and normal urothelial cells

Constitutive activation of WNT signalling through beta-catenin, which leads to increased transcription of TCF/beta-catenin target genes, is crucial in the development of many human tumour types including colorectal carcinoma and hepatoma. Its role in urothelial cancer (TCC) is unclear, since typical activating mutations are not found. We therefore determined the activity of a beta-catenin/TCF-dependent promoter in proliferating normal uroepithelial cells and seven TCC cell lines, using a hepatoma line with oncogenic beta-catenin as a control. Neither normal urothelial cells nor TCC lines exhibited activity under normal growth conditions. In normal cells and 5/7 TCC lines, even transfection of activated beta-catenin did not restore promoter activity, suggesting repression of beta-catenin/TCF activity. TCF mRNAs and total beta-catenin protein levels did not differ qualitatively between inducible and noninducible cell lines, but E-cadherin expression was lacking or low in inducible TCC lines. In these, cotransfection of E-cadherin diminished activation of the TCF-dependent promoter by beta-catenin. Our results make constitutive WNT/beta-catenin signalling in TCC appear unlikely, thereby explaining the lack of reported mutations. However, decreased E-cadherin expression occurring in many TCC, often as a consequence of promoter hypermethylation, may confer inappropriate responsiveness to WNT factors.

Development of a real-time reverse transcription polymerase chain reaction assay for c-myc expression that allows the identification of a subset of c-myc+ diffuse large B-cell lymphoma

Absence of a reliable method for determining the level of c-myc expression has impeded the analysis of its biological and clinical relevance in tumors. We have standardized the conditions for a real-time reverse transcription polymerase chain reaction analysis for c-myc expression, including the selection of an endogenous reference (18S rRNA), the adequate number of measurements for each sample (2 cDNA in triplicate), and suitable controls for determining inter- and intrarun variability (standard curve and calibrator). Subsequently, in a series of 56 non-Hodgkin's lymphomas, we analyzed the expression of c-myc mRNA, using real-time reverse transcription polymerase chain reaction, and of other functionally related proteins (bcl-6, p27, cyclin D3, and p53). As expected, all eight Burkitt's lymphoma cases analyzed had high levels of c-myc mRNA expression compared with that observed in reactive lymphoid tissue. There was a wider range of expression in diffuse large B-cell lymphoma, with 30% (15 of 48) of cases overexpressing c-myc. This overexpression was largely independent of c-myc translocations (4 of 5), as demonstrated by fluorescence in situ hybridization. In this large B-cell lymphoma series, a high level of c-myc expression predicted lower survival probability, irrespectively of the International Prognostic Index risk group classification. A slightly increased frequency of p53 inactivation was observed in the cases with c-myc overexpression, which suggests a growth advantage in lymphomas with concurrent deregulation of c-myc and p53. In addition, a moderate increase in bcl-6 protein expression was observed in the c-myc-positive cases, suggesting the existence of a complex interrelationship between these two genes. These findings suggest that c-myc may play a relevant role in the pathogenesis of a subset of large B-cell lymphoma and suggest the existence of additional regulatory mechanisms of c-myc expression to c-myc rearrangements.

Beta-catenin mutations correlate with over expression of C-myc and cyclin D1 Genes in bladder cancer

PURPOSE

We hypothesized that over expression of c-myc and cyclin D1 genes is transcriptionally activated by beta-catenin mutation independent of gene amplification in bladder cancer. To test this hypothesis we investigated the relationship of beta-catenin mutation to c-myc and cyclin D1 mRNA with special reference to the changes in copy number of the 2 genes.

MATERIALS AND METHODS

Genomic DNA and total RNA were extracted from 59 bladder cancer specimens and from 31 histologically normal specimens of bladder mucosa. We performed beta-catenin deletion screening by polymerase chain reaction (PCR) using primers spanning exons 3 (including the glycogen synthase kinase-3beta consensus motif), 5 and 6. Mutational changes in beta-catenin in exons 3, 5 and 6 were detected by each PCR-single strand conformational polymorphism analysis followed by direct DNA sequencing. mRNA expression and copy numbers of c-myc and cyclin D1 were determined by semiquantitative reverse transcriptase-PCR and competitive genomic PCR.

RESULTS

Missense mutations of beta-catenin found in grade 3 bladder cancer were involved in the consensus motif of glycogen synthase kinase-3beta in exon 3. These cancers showed strong intracellular accumulation of beta-catenin and intense expression of c-myc and cyclin D1 mRNA compared with samples lacking the beta-catenin mutation. When grade 3 cancers were compared, expression levels of c-myc and cyclin D1 mRNA were still higher in those with versus without the beta-catenin mutation. In bladder cancers with beta-catenin mutations copy numbers of the c-myc and cyclin D1 genes did not amplify.

CONCLUSIONS

Bladder cancer harboring a beta-catenin mutation may represent aggressive biological behavior with enhanced proliferating activity. These findings are important for understanding the role of beta-catenin mutation in the pathogenesis of bladder cancer.

c-MYC activation in primary and metastatic ductal adenocarcinoma of the pancreas: incidence, mechanisms, and clinical significance

Amplification and overexpression of c-MYC is a common event in various neoplasias. Recently, comparative genomic hybridization (CGH) of primary pancreatic adenocarcinomas revealed a distinct high-level amplification of 8q23-qter, suggesting that c-MYC located on 8q24 may be a candidate oncogene. To evaluate the biological significance and prognostic value of c-MYC activation in pancreatic carcinoma, we performed interphase fluorescence in situ hybridization (FISH) and immunohistochemistry on a series of 69 primary pancreatic adenocarcinomas, 19 corresponding lymph node metastases, and 5 pancreatic intraductal lesions. Dual color FISH using a probe for c-MYC (8q24) and a centromeric probe for chromosome 8 revealed amplification of c-MYC in 32.3% and 29.4% of primary and metastatic tumors, respectively. Immunostaining identified c-MYC protein overexpression in 43.5% of primaries and 31.6% of metastases. Low concordance between positive FISH and immunostaining (13.4%) suggests multiple independent regulatory pathways of c-MYC activation. Statistical evaluation revealed significant correlation (alpha = 0.033) between c-MYC protein overexpression and histopathological tumor grade but absence of correlation with tumor stage or lymph node status. Analysis of pancreatic intraductal lesions showed c-MYC amplification and protein overexpression in two of five cases in which invasive carcinoma exhibited identical aberrations. We conclude that deregulation of c-MYC protein is common in pancreatic cancer and that it may be involved in early neoplastic development and progression rather than in locoregional spread of invasive cancer.

CENP-F gene amplification and overexpression in head and neck squamous cell carcinomas

BACKGROUND

Antibodies against cancer-related genes have been detected in human cancers including head and neck cancers. High titers of c-Myc autoantibodies have been linked to gene amplification and tumor progression. Centromere protein-F (CENP-F) autoantibodies have been detected in patients with various cancers, suggesting similar gene alteration.

METHODS

CENP-F and c-MYC amplification was assessed in 72 head and neck squamous cell carcinoma (HNSCC) patients. Tumor and matched mucosa from 22 patients were analyzed for CENP-F mRNA levels by RT-PCR.

RESULTS

The larynx was the site most altered by amplification of either gene. CENP-F and c-MYC were amplified in 11% and 17% of the tumors, respectively. Coamplification was found in 7% of the tumors, most of which showed regional node involvement. CENP-F mRNA was overexpressed in 36% of tumors, and 23% of paired mucosa.

CONCLUSION

Our results provide the first evidence that CENP-F gene is amplified and overexpressed in HNSCC. No correlation was noted between CENP-F amplification and clinicopathologic parameters. However, CENP-F overexpression correlated with nodal metastasis.