| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Molecular Biology and Genetics |
Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 [S. Y., T. K., F. T., K. H., C. M. C.], and Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania 19104 [A. C. H., K. R. D., N. N. W., L. R. K.]
| ABSTRACT |
|---|
|
|
|---|
| INTRODUCTION |
|---|
|
|
|---|
Lung cancer is strongly associated with exposure to environmental carcinogens, particularly tobacco smoke. It has been suggested that carcinogen-induced alterations are more frequent at fragile sites and that genes located at these fragile sites are frequently altered because of such exposure. If these genes are tumor suppressor genes, such alterations may provide an etiologic mechanism for carcinogenesis (3 , 4) . A common, early, and consistent alteration found in lung cancer is the loss of Fhit expression (5) . We have speculated that the frequent alterations of FHIT, a gene located in the fragile region FRA3B (6) , in tumors associated with environmental carcinogens are because of the fact that this region of the genome is particularly susceptible to breakage. This speculation is also supported by studies that show that the frequency of loss of Fhit expression is higher in tumors of patients with alterations of genes involved in DNA repair such as BRCA2, BRCA1, and MSH2 (7, 8, 9) .
WWOX, like FHIT, is located at a common fragile region, FRA16D (10) , and seems to be involved in cancers of the breast, ovary, and esophagus (11, 12, 13) . The pattern of WWOX alterations is similar to that of FHIT in that point mutations are extremely rare (14 , 15) , but biallelic deletions are common (15) . Given the fact that environmental carcinogens may preferentially induce alterations in fragile regions and because of the strong association of tobacco smoking with lung cancer, we hypothesized that the WWOX gene at FRA16D may be altered in a significant fraction of NSCLCs.
| MATERIALS AND METHODS |
|---|
|
|
|---|
Reverse Transcriptase-PCR.
Nested reverse transcriptase-PCR was performed using 1 µl of cDNA. The first and second amplifications were performed with nested primers (forward primer 5'-AGTTCCTGAGCGAGTGGACC-3'; reverse primer 5'-TTACTTTCAAACAGGCCACCAC-3') and (forward primer 5'-AGGTGCCTCCACAGTC-3'; reverse primer 5'-GTGTGTGCCCATCCGCTCT-3'), respectively. Both reactions were carried out in a volume of 50 µl containing 20 pmol of each primer, 2.5 mM MgCl2, 0.2 mM deoxynucleotide triphosphate mix, 1x PCR buffer, and 2.5 units of AmpliTaq Gold (Perkin-Elmer, Life Sciences Inc., Boston, MA). The PCR program was set for one cycle of 95°C for 8 min followed by 35 cycles of 94°C for 30 s, 57°C for 30 s, and 72°C for 1 min with an extension step of 72°C for 5 min in a Perkin-Elmer Gene Amp PCR System 9600. One µl of the amplification product from the first reaction was used for the second reaction. After running the products on a 1.5% agarose gel, the normal and abnormal bands were excised and purified using the QIAquick gel extraction kit (Qiagen, Inc., Valencia, CA) and sequenced on an Applied Biosystems Prism 377 DNA sequencing system using appropriate primers. Glyceraldehyde-3-phosphate dehydrogenase amplification served as a control for cDNA quality.
Exon PCR and Mutation Analysis.
PCR amplification of individual exons from genomic DNA of lung cancer cell lines and paired normal lung and tumor tissue was performed using primers described previously (GenBank Accession Nos. AF325423-AF325432; Ref. 10
). The reaction conditions were: 50 ng of genomic DNA template; 10 pmol of each primer; 2.5 mM MgCl2; 1.5 mM deoxynucleotide triphosphate mix; 1x PCR buffer; and 0.5 unit of AmpliTaq Gold (Perkin-Elmer, Boston, MA) in a 20-µl final volume in a Perkin-Elmer Gene Amp PCR system 9600. PCR cycles used were one cycle at 95°C for 12 min, succeeded by 10 cycles at 94°C for 15 s, 55°C for 15 s, and 72°C for 30 s. This was followed by 25 cycles at 89°C for 15 s, 55°C for 15 s, and 72°C for 30 s. An elongation cycle of 72°C for 10 min completed the sequence. After purification of the PCR products using the QIAquick PCR purification kit (Qiagen, Inc.), sequencing was performed using an Applied Biosystems Prism 377 DNA sequencing system (Applied Biosystem, Inc.).
LOH Analysis.
Allelic losses were analyzed by PCR amplification of polymorphic microsatellites internal to WWOX at loci D16S3029, D16S3096, D16S504, and D16S518 as described elsewhere (12)
. Briefly, primers were obtained from the Genome database and labeled using 5'-fluorescein phosphoramidite or 5'-tetrachlorofluorescein phosphoramidite, as described by Ishii et al. (16)
. PCR was performed on 50 ng of DNA for each sample using conditions described for the mutation search. PCR products were denatured in formamide for 5 min at 95°C and then loaded on a 6% denaturing gel on the Applied Biosystems 373 DNA sequencer. LOH was analyzed by using the Applied Biosystems Prism Genescan and the Applied Biosystems Prism Genetyper Analysis software (Perkin-Elmer/Applied Biosystems). Cases were defined as exhibiting LOH when an allele peak signal from DNA was reduced by 30% compared with the normal counterpart.
| RESULTS |
|---|
|
|
|---|
Aberrant WWOX Transcripts in Tumor Cell Lines and Tumors.
As reported previously, WWOX mRNA expression is too low to be detectable routinely by Northern blot of RNA from small tumor samples (12)
. Hence, reverse transcriptase-PCR amplification was performed to analyze WWOX expression. Of 27 cases of NSCLC studied, 7 showed transcripts with missing exons. Of these 7, 2 tumor samples (cases B-83 and B-86) did not exhibit a normal sized transcript. In all 27 pairs, corresponding normal tissues demonstrated normal size transcripts without aberrant transcripts. Sequence analysis of the reverse transcriptase-PCR amplification products showed the alterations summarized in Table 1
. Of 8 cell lines studied by reverse transcriptase-PCR, aberrant transcripts were found in 5 (Fig. 1)
. Interestingly, sequencing of several of these aberrant amplification products (in cell lines NCI-H23, NCI-H1650, and NCI-H1573) showed frameshifts in the open reading frame (Fig. 2)
.
|
|
|
LOH Analysis.
To evaluate the frequency of allelic loss of WWOX in NSCLC, we performed a search for LOH using four polymorphic microsatellite markers within the gene. The loci D16S3029, D16S3096, and D16S504 are located in intron 7 and the locus D16S518 is located in exon 1. All of the samples were informative for at least one marker. Of 27 paired normal and tumor samples, LOH was detected in 10 samples (37.0%); 4 of 11 (36.4%) squamous cell cancers; and 3 of 10 (30.0%) adenocarcinomas (Table 2)
.
|
| DISCUSSION |
|---|
|
|
|---|
Our data are consistent with the pattern of WWOX alterations described by others. Bednarek et al. (10)
have demonstrated aberrant transcripts in >30% of primary breast tumors. The demonstration of LOH using several microsatellite markers in intron 7 is consistent with a previous report in which the authors discuss the high susceptibility to breakage in the intron 8 region (10)
. Previous results also demonstrated that while LOH within WWOX is common, WWOX point mutations are rare (11
, 12) . Point mutations were not detected in the 27 primary tumors studied; one possible mutation was detected in codon 183 in exon 6 of cell line NCI-H23. This alteration involves a substitution of aspartic acid with asparagine and has not been described before. It was not described in a previous study of >100 normal (noncancerous) samples and in
80 normal samples that we have analyzed thus far (unpublished data). Exon 6 encodes part of the second oxidoreductase domain of the Wwox protein (17)
. However, as this alteration was found in an established cell line and the normal counterpart was unavailable, we cannot rule out the possibility that this alteration is a previously undescribed polymorphism.
This pattern of alterations is similar to that of the FHIT gene in human tumors, and it is speculated that this is because of its location at a fragile site in the human genome. WWOX, like FHIT, encompasses a common fragile site. Both genes are very large (>1 Mb) and encode relatively small proteins. The occurrence of LOH in primary tumor samples is especially significant in light of evidence that the FHIT gene can function as a one-hit tumor suppressor gene in some tissues (18) . In the study by Zanesi et al. (18) , Fhit+/- mice had almost the same propensity for the development of tumors as Fhit-/- mice. It is possible that loss of one WWOX allele could have a biological effect. Haploinsufficiency of other tumor suppressor genes has also been demonstrated to confer tumor susceptibility (19) .
Among lung cancer derived cell lines, aberrant reverse transcriptase-PCR products were detected in 5 of 8 cell lines. Most aberrant reverse transcriptase-PCR products in tumor cases, as well as cell lines, demonstrated absence of exons 5, 6, 7, and 8. These exons encode the oxidoreductase domains of the Wwox protein (17) and their absence may have a functional consequences. It has been demonstrated that altered transcripts produce proteins that show a different pattern of localization from the wild-type protein (20) . It has also been postulated that altered transcripts may have a dominant negative effect (20) .
Fhit-deficient mice are very sensitive to tumor induction by carcinogens. Carcinogen exposure is strongly associated with loss of Fhit expression. Presumably, the location of these genes in fragile sites makes them susceptible to breakage when exposed to carcinogens. Thus, WWOX alterations could also be common in cancers caused primarily by carcinogen exposure. This is supported by previous evidence that WWOX alterations are common in esophageal cancer (12) ; esophageal cancer is strongly associated with exposure to carcinogens in tobacco smoke and alcohol (21) . Our results additionally support the hypothesis that carcinogen exposure may lead to alterations of genes spanning fragile sites. In this context, it is interesting that the incidence of WWOX alterations was more frequent in squamous cell carcinomas than in adenocarcinomas of the lung (55.5 versus 20%); the incidence of squamous cell cancer is more strongly associated with tobacco smoke than adenocarcinoma (22) .
FHIT gene therapy has been used in both in vitro and in vivo experiments with promising results. With previous evidence suggesting that viral mediated overexpression of WWOX can lead to inhibition of tumorigenicity (20) , understanding the pathways involved in the tumor suppressor function of WWOX may provide novel targets for therapy of NSCLC.
| FOOTNOTES |
|---|
1 This work was supported by a generous donation from the Falk Trust. ![]()
2 Both authors contributed equally to the study. ![]()
3 To whom requests for reprints should be addressed, at Kimmel Cancer Center, 233 South Tenth Street, BLSb Room1050, Philadelphia, PA 19104. Phone: (215) 503-4645; Fax: (215) 923-3528; E-mail: croce{at}calvin.jci.tju.edu ![]()
4 The abbreviations used are: NSCLC, non-small cell lung cancer; WWOX, WW domain containing oxidoreductase gene; LOH, loss of heterozygosity; FHIT, fragile histidine triad gene. ![]()
Received 10/16/02. Accepted 12/16/02.
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
C. Gourley, A. J.W. Paige, K. J. Taylor, C. Ward, B. Kuske, J. Zhang, M. Sun, S. Janczar, D. J. Harrison, M. Muir, et al. WWOX Gene Expression Abolishes Ovarian Cancer Tumorigenicity In vivo and Decreases Attachment to Fibronectin via Integrin {alpha}3 Cancer Res., June 1, 2009; 69(11): 4835 - 4842. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. I. Aqeilan, F. Trapasso, S. Hussain, S. Costinean, D. Marshall, Y. Pekarsky, J. P. Hagan, N. Zanesi, M. Kaou, G. S. Stein, et al. Targeted deletion of Wwox reveals a tumor suppressor function PNAS, March 6, 2007; 104(10): 3949 - 3954. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. Donati, G. Fontanini, M. Dell'Omodarme, M. C. Prati, S. Nuti, M. Lucchi, A. Mussi, M. Fabbri, F. Basolo, C. M. Croce, et al. WWOX Expression in Different Histologic Types and Subtypes of Non-Small Cell Lung Cancer Clin. Cancer Res., February 1, 2007; 13(3): 884 - 891. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Gaudio, A. Palamarchuk, T. Palumbo, F. Trapasso, Y. Pekarsky, C. M. Croce, and R. I. Aqeilan Physical Association with WWOX Suppresses c-Jun Transcriptional Activity Cancer Res., December 15, 2006; 66(24): 11585 - 11589. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. A. Walker, P. E. Leone, M. W. Jenner, C. Li, D. Gonzalez, D. C. Johnson, F. M. Ross, F. E. Davies, and G. J. Morgan Integration of global SNP-based mapping and expression arrays reveals key regions, mechanisms, and genes important in the pathogenesis of multiple myeloma Blood, September 1, 2006; 108(5): 1733 - 1743. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Fabbri, D. Iliopoulos, F. Trapasso, R. I. Aqeilan, A. Cimmino, N. Zanesi, S. Yendamuri, S.-Y. Han, D. Amadori, K. Huebner, et al. WWOX gene restoration prevents lung cancer growth in vitro and in vivo PNAS, October 25, 2005; 102(43): 15611 - 15616. [Abstract] [Full Text] [PDF] |
||||
![]() |
F.-J. Lai, C.-L. Cheng, S.-T. Chen, C.-H. Wu, L.-J. Hsu, J. Y.-Y. Lee, S.-C. Chao, M.-C. Sheen, C.-L. Shen, N.-S. Chang, et al. WOX1 Is Essential for UVB Irradiation-Induced Apoptosis and Down-Regulated via Translational Blockade in UVB-Induced Cutaneous Squamous Cell Carcinoma In vivo Clin. Cancer Res., August 15, 2005; 11(16): 5769 - 5777. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. I. Aqeilan, A. Palamarchuk, R. J. Weigel, J. J. Herrero, Y. Pekarsky, and C. M. Croce Physical and Functional Interactions between the Wwox Tumor Suppressor Protein and the AP-2{gamma} Transcription Factor Cancer Res., November 15, 2004; 64(22): 8256 - 8261. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. I. Aqeilan, T. Kuroki, Y. Pekarsky, O. Albagha, F. Trapasso, R. Baffa, K. Huebner, P. Edmonds, and C. M. Croce Loss of WWOX Expression in Gastric Carcinoma Clin. Cancer Res., May 1, 2004; 10(9): 3053 - 3058. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. C. Picchio, E. S. Martin, R. Cesari, G. A. Calin, S. Yendamuri, T. Kuroki, F. Pentimalli, M. Sarti, K. Yoder, L. R. Kaiser, et al. Alterations of the Tumor Suppressor Gene Parkin in Non-Small Cell Lung Cancer Clin. Cancer Res., April 15, 2004; 10(8): 2720 - 2724. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Kuroki, S. Yendamuri, F. Trapasso, A. Matsuyama, R. I. Aqeilan, H. Alder, S. Rattan, R. Cesari, M. L. Nolli, N. N. Williams, et al. The Tumor Suppressor Gene WWOX at FRA16D Is Involved in Pancreatic Carcinogenesis Clin. Cancer Res., April 1, 2004; 10(7): 2459 - 2465. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. I. Aqeilan, Y. Pekarsky, J. J. Herrero, A. Palamarchuk, J. Letofsky, T. Druck, F. Trapasso, S.-Y. Han, G. Melino, K. Huebner, et al. Functional association between Wwox tumor suppressor protein and p73, a p53 homolog PNAS, March 30, 2004; 101(13): 4401 - 4406. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Watanabe, Y. Hippo, H. Taniguchi, H. Iwanari, M. Yashiro, K. Hirakawa, T. Kodama, and H. Aburatani An Opposing View on WWOX Protein Function as a Tumor Suppressor Cancer Res., December 15, 2003; 63(24): 8629 - 8633. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Ishii, A. Vecchione, Y. Furukawa, K. Sutheesophon, S.-Y. Han, T. Druck, T. Kuroki, F. Trapasso, M. Nishimura, Y. Saito, et al. Expression of FRA16D/WWOX and FRA3B/FHIT Genes in Hematopoietic Malignancies Mol. Cancer Res., November 1, 2003; 1(13): 940 - 947. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |