Abnormal CD44 Gene Expression in Neoplasia: Biological and Clinical Implications
The CD44 gene is one of the most interesting and promising new candidate markers for early cancer detection and for the analysis of genetic disturbances involved in neoplasia. It a large gene that under normal circumstances produces a variety of heavily glycosylated cell surface proteins by alternative splicing of its exons. Severe abnormalities have been observed in its patterns of expression in many types of common human tumors by both protein and RNA analyses. They are manifested by markedly increased levels of unusual CD44 transcripts and proteins in many tumors compared to corresponding normal tissues. Also, inappropriate expression patterns of the alternatively spliced exons have been linked to both tumor growth and metastatic potential. A unique manifestation of aberrant CD44 gene expression is the retention of introns in mature mRNA transcripts in the nucleus and cytoplasm of tumor cells but not in their normal counterparts. This phenomenon would naturally result in abnormal or truncated protein products. The clinical relevance of these observations is demonstrated by the frequent detection of all these abnormalities in fresh tissue samples from tumors of many organs and by their presence in preinvasive and high risk precancerous lesions. It has also been possible to achieve noninvasive detection of malignancy by identifying aberrant CD44 expression in exfoliated cells in body fluids and waste products. This chapter reviews the molecular mechanisms that result in such profound misregulation of the expression of this gene in neoplasia and the biological and clinical implications of these changes for tumors of the gastrointestinal tract.
This chapter is an account of current ideas and information on one of the most interesting and mysterious components in the mammalian genetic repertoire. It is still known only by the code name CD44, indicating that its products and functions are largely unknown, although it has leapt to the forefront of attention and curiosity because its expression is so strikingly unusual in many common types of cancer, including those of the gastrointestinal tract and because it appears to be involved in a large variety of biological processes that are unrelated to each other.
The group of proteins encoded by this locus first attracted interest as a result of efforts by several research laboratories to identify and characterize cell surface molecules on white blood cells that might be important in cell-mediated immunity. These investigations included studies to isolate molecules involved in organizing the recirculatory traffic of lymphocytes as they patrol the organs of the body on surveillance missions . The work resulted in the raising of a number of monoclonal antibodies (mAbs), which were eventually recognized to bind to different epitopes on a family of structurally related proteins assigned the designation CD (cluster of differentiation) 44 by the Human Leukocyte Workshop.
Subsequent studies [2, 3] with these antibodies rapidly made it clear that the CD44 family of proteins are not confined to the surfaces of white blood cells, and that some of them appear to be ubiquitously distributed on all cell types. It also emerged almost simultaneously that they are involved not just in immunological activities but in a surprising diversity of biological processes [4, 5], although their exact role in these processes remains unclear. Some of the functions in which they have been implicated include the following.
Shortly afterward various parts of the gene were cloned and sequenced by several groups [6–11], and it became evident that by alternative splicing of its exons it can produce a large variety of protein isoforms. It appears to be one of the most alternatively spliced genes yet found.
The human CD44 gene has now been mapped to the chromosomal locus 11p13 and confirmed to encode a family of large transmembrane glycoproteins. It is composed of a stretch of approximately 60 kb comprising at least 21 exons, 10 of which (exons 1–5 and 16–20) are constantly expressed on all cell types as the standard form (CD44s). The remaining 11 can be alternatively spliced with the constant ones (Fig. 1) to generate a number of variant protein isoforms (CD44v), which can be further modified by differential post-translational glycosylation.
The complexity of the processes in which this gene is involved in cell and tissue function was further revealed when it became apparent that its expression is characteristically and severely changed in many common types of neoplasia, and that such dysfunction is involved in the acquisition of metastatic ability in some circumstances. The following account summarizes current knowledge of the unusual patterns of CD44 expression in cancer and considers their clinical and biological implications.
KeywordsCD44 Gene CD44 Protein Early Cancer Detection CD44 Isoforms CD44 Gene Expression
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
Culty M, Miyake K, Kincade PW, Sikorski E, Butcher EC, Underhill C, Sikorski E (1990) The hyaluronate receptor is a member of the CD44 (HCAM) family of cell surface glycoproteins. J Cell Biol 111:2765–2774PubMedCrossRefGoogle Scholar
Picker LJ, Nakache M, Butcher EC (1989) Monoclonal antibodies to human lymphocyte homing receptors define a novel class of adhesion molecules on diverse cell types. J Cell Biol 109:927–937PubMedCrossRefGoogle Scholar
Mackay CR, Terpe H-J, Stauder R, Marston WL, Stark H, Gunthert U (1994) Expression and modulation of CD44 variant isoforms in humans. J Cell Biol 124:71–82PubMedCrossRefGoogle Scholar
Haynes BF, Telen MJ, Hale LP, Denning SM (1989) CD44—a molecule involved in leukocyte adherence and T-cell activation. Immunol Today 10:423–428PubMedCrossRefGoogle Scholar
Lesley J, Hyman R, Kincade PW (1993) CD44 and its interaction with the extracellular matrix. Adv Immunol 54:27–335Google Scholar
Stamenkovic I, Amiot M, Pesando JM, Seed B (1989) A lymphocyte molecule implicated in lymph node homing is a member of the cartilage link protein family. Cell 56:1057–1062PubMedCrossRefGoogle Scholar
Hofmann M, Rudy W, Zoller M, Tolg C, Ponta H, Herrlich P, Gunthert U (1991) CD44 splice variants confer metastatic behaviour in rats: homologous sequences are expressed in human tumour cell lines. Cancer Res 51:5292–5297PubMedGoogle Scholar
Screaton GR, Bell MV, Jackson DG, Cornelis FB, Gerth U, Bell JI (1992) Genomic structure of DNA encoding the lymphocyte homing receptor CD44 reveals at least 12 alternatively spliced exons. Proc Natl Acad Sci USA 89:12160–12164PubMedCrossRefGoogle Scholar
Tolg C, Hofmann M, Herrlich P, Ponta H (1993) Splicing choice from ten variant exons establishes CD44 variability. Nucleic Acids Res 21:1225–1229PubMedCrossRefGoogle Scholar
Matsumura Y, Hanbury D, Smith J, Tarin D (1994) Non-invasive detection of malignancy by identification of unusual CD44 gene activity in exfoliated cancer cells. BMJ 308:619–624PubMedCrossRefGoogle Scholar
Matsumura Y, Sugiyama M, Matsumura S, Hayle AJ, Robinson P, Smith JC, Tarin D (1995) Unusual retention of introns in CD44 gene transcripts in bladder cancer provides new diagnostic and clinical oncological opportunities. J Pathol 177:11–20PubMedCrossRefGoogle Scholar
Stamenkovic I, Aruffo A, Amiot M, Seed B (1991) The hematopoietic and epithelial forms of CD44 are distinct polypeptides with different adhesion potentials for hyaluronate-bearing cells. EMBO J 10:343–348PubMedGoogle Scholar
Birch M, Mitchell S, Hart IR (1991) Isolation and characterization of human melanoma cell variants expressing high and low levels of CD44. Cancer Res 51:6660–6667PubMedGoogle Scholar
Sy MS, Guo Y-J, Stamenkovic I (1991) Distinct effects of two CD44 isoforms on tumor growth in vivo. J Exp Med 174:859–866PubMedCrossRefGoogle Scholar
Matsumura Y, Tarin D (1992) Significance of CD44 gene products for cancer diagnosis and disease evaluation. Lancet 340:1053–1058PubMedCrossRefGoogle Scholar
Gunthert U, Hofmann M, Rudy W, Reber S, Zoller M, Hau-Bmann I, Matzku S, Wenzel A, Ponta H, Herrlich P (1991) A new variant of glycoprotein CD44 confers metastatic potential to rat carcinoma cells. Cell 65:13–24PubMedCrossRefGoogle Scholar
Tarin D, Bolodeoku J, Hatfill SJ, Sugino T, Woodman AC, Yoshida K (1995) The clinical significance of malfunction of the CD44 locus in malignancy. J Neurooncol 26:209–219PubMedCrossRefGoogle Scholar
Yokozaki H, Ito R, Nakayama H, Kuniyasu H, Taniyama K, Tahara E (1994) Expression of CD44 abnormal transcripts in human gastric carcinomas. Cancer Lett 83:229–234PubMedCrossRefGoogle Scholar
Imazeki F, Yokosuka O, Yamaguchi T, Ohto M, Isono K, Omata M (1996) Expression of variant CD44-messenger RNA in colorectal adenocarcinomas and adenomatous polyps in humans. Gastroenterology 110:362–368PubMedCrossRefGoogle Scholar
Gorham H, Sugino T, Woodman AC, Tarin D (1996) Cellular distribution of CD44 gene transcripts in colorectal carcinomas and in normal colonic mucosa. J Clin Pathol 49:482–488PubMedCrossRefGoogle Scholar
Sugino T, Gorham H, Yoshida K, Bolodeoku J, Nargund V, Cranston D, Goodison S, Tarin D (1996) Progressive loss of CD44 gene expression in invasive bladder cancer. Am J Pathol 149:873–882PubMedGoogle Scholar
Orzechowski HD, Beckenbach C, Herbst H, Stolzel U, Riecken EO, Stallmach A (1995) Expression of CD44v6 is associated with cellular dysplasia in colorectal epithelial cells. Eur J Cancer 31A:2073–2079PubMedCrossRefGoogle Scholar
Gorham H, Sugino T, Bolodeoku J, Yoshida K, Goodison S, Tarin D (1996) Distribution of CD44 messenger RNA in archival paraffin wax embedded tumours and normal tissues viewed by in situ hybridisation. J Clin Pathol Mol Pathol 49:M147–M150CrossRefGoogle Scholar
Yoshida K, Bolodeoku J, Sugino T, Goodison S, Matsumura Y, Warren BF, Toge T, Tahara E, Tarin D (1995) Abnormal retention of intron 9 in CD44 gene transcripts in human gastrointestinal tumors. Cancer Res 55:4273–4277PubMedGoogle Scholar
Higashikawa K, Yokozaki H, Ue T, Taniyama K, Ishikawa T, Tarin D (1996) Evaluation of CD44 transcription variants in human digestive tract carcinomas and normal tissues. Int J Cancer 66:11–17PubMedCrossRefGoogle Scholar
Bolodeoku J, Yoshida K, Sugino T, Goodison S, Tarin D (1996) Accumulation of immature introncontaining CD44 gene transcripts in breast cancer tissues. Mol Diag 1:175–181CrossRefGoogle Scholar
Heider K-H, Hofmann M, Hors E, van den Berg F, Ponta H, Herrlich P, Pals ST (1993) A human homologue of the rat metastasis-associated variant of CD44 is expressed in colorectal carcinomas and adenomatous polyps. J Cell Biol 120:227–233PubMedCrossRefGoogle Scholar
Wielenga VJM, Heider K-H, Offerhaus GJA, Adolf GR, van den Berg FM, Ponta H, Herrlich P, Pals ST (1993) Expression of CD44 variant proteins in human colorectal cancer is related to tumor progression. Cancer Res 53:4754–4756PubMedGoogle Scholar
Borgya A, Woodman A, Sugiyama M, Donie F, Kopetzki E, Matsumura Y, Tarin D (1995) Isolation and characterisation of antibodies which specifically recognise the peptide encoded by exon 7 (v2) of the human CD44 gene. J Clin Pathol Mol Pathol 48:M241–M250CrossRefGoogle Scholar
Kawahara K, Yoshino T, Kawasaki N, Miyake K, Akagi T (1996) Abnormal expression of the human CD44 gene in early colorectal malignancy with special reference to variant exon 9 (9v). J Clin Pathol 49:478–481PubMedCrossRefGoogle Scholar
Dall P, Heider K-H, Hekele A, von Minchwitz G, Kaufmann M, Ponta H, Herrlich P (1994) Surface protein expression and messenger RNA-splicing analysis of CD44 in uterine cervical cancer and normal cervical epithelium. Cancer Res 54:3337–3341PubMedGoogle Scholar
Mulder J-WR, Kruyt PM, Sewnath M, Oosting J, Seldenrijk CA, Weidema WF, Offerhaus GJA, Pals ST (1994) Colorectal cancer prognosis and expression of exon-v6-containing CD44 proteins. Lancet 344:1470–1472PubMedCrossRefGoogle Scholar
Friedrichs K, Franke F, Lisboa B-W, Kugler G, Gille I, Terpe H-J, Holzel F, Maass H, Gunthert U (1995) CD44 isoforms correlate with cellular differentiation but not with prognosis in human breast cancer. Cancer Res 55:5424–5433PubMedGoogle Scholar
Woodman AC, Sugiyama M, Yoshida K, Sugino T, Borgya A, Goodison S, Matsumura Y, Tarin D (1996) Analysis of anomalous CD44 gene expression in human breast, bladder and colon cancer and correlation with observed mRNA and protein isoforms. Am J Pathol 149:1519–1530PubMedGoogle Scholar
Guo Y-J, Liu G, Wang X, Jin D, Wu M, Ma J, Sy MS (1994) Potential use of soluble CD44 in serum as indicator of tumor burden and metastasis in patients with gastric or colon cancer. Cancer Res 54:422–426PubMedGoogle Scholar
Rudy W, Hofmann M, Schwartz-Albiez R, Zoller M, Heider K-H, Ponta H, Herrlich P (1993) The two major CD44 proteins expressed on a metastatic rat tumor cell line are derived from different splice variants: each one individually suffices to confer metastatic behavior. Cancer Res 53:1262–1268PubMedGoogle Scholar
Driessens MH, Stroeken PJ, Rodriguez-Erena NF, van-der-Valk MA, van Rijthoven EA, Roos E (1995) Targeted disruption of CD44 in MDAY-D2 lymphosarcoma cells has no effect on subcutaneous growth or metastatic capacity. J Cell Biol 131:1849–1855PubMedCrossRefGoogle Scholar
Yoshida K, Sugino T, Bolodeoku J, Warren BF, Goodison S, Woodman A, Toge T, Tahara E, Tarin D (1996) Detection of exfoliated carcinoma cells in colonic luminal washings by identification of deranged patterns of expression of the CD44 gene. J Clin Pathol 49:300–305PubMedCrossRefGoogle Scholar
Kaufmann M, Heider K-H, Sinn H-P, von Minckwitz G, Ponta H, Herrlich P (1995) CD44 variant exon epitopes in primary breast cancer and length of survival. Lancet 345:615–619PubMedCrossRefGoogle Scholar
Koopman G, Heider K-H, Horst E, Adolf GR, van den Berg F, Ponta H, Herrlich P, Pals ST (1993) Activated human lymphocytes and aggressive nonHodgkin’s lymphomas express a homologue of the rat metastasis-associated variant of CD44. J Exp Med 177:897–904PubMedCrossRefGoogle Scholar
Finn L, Dougherty G, Finley G, Meisler A, Becich M, Cooper DL (1994) Alternative splicing of CD44 pre-mRNA in human colorectal tumors. Biochem Biophys Res Commun 200:1015–1022PubMedCrossRefGoogle Scholar
Lee J-H, Kang YS, Kim BG, Park SY, Lee KH, Park KB (1995) Expression of the CD44 adhesion molecule in primary and metastatic gynecologic malignancies and their cell lines. Int J Gynecol Cancer 5:193–199PubMedCrossRefGoogle Scholar
Takeuchi K, Yamaguchi A, Urano T, Goi T, Nakagawara G, Shiku H (1995) Expression of CD44 variant exons 8–10 in colorectal cancer and its relationship to metastasis. Jpn J Cancer Res 86:292–297PubMedCrossRefGoogle Scholar
Clarke MR, Landreneau RJ, Resnick NM, Crowley R, Dougherty GJ, Cooper DL, Yousem SA (1995) Prognostic significance of CD44 expression in adenocarcinoma of the lung. J Clin Pathol Mol Pathol 48:M200–M204CrossRefGoogle Scholar
Sugiyama M, Woodman A, Sugino T, Crowley S, Ho K, Smith J, Matsumura Y, Tarin D (1995) Noninvasive detection of bladder cancer by identification of abnormal CD44 proteins in exfoliated cancer cells in urine. J Clin Pathol Mol Pathol 48:M142–M147CrossRefGoogle Scholar
Tarin D, Matsumura Y (1993) Deranged activity of the CD44 gene and other loci as biomarkers for progression to metastatic malignancy. J Cell Biochem 17G:173–185CrossRefGoogle Scholar