Cancer
Letters.
Elsevier
57 (1991)
Scientific
131
131-135
Publishers
Ireland
Ltd.
Cadherin intercellular adhesion carcinomas: loss of E-cadherin undifferentiated carcinoma Y.
Shirnoyarna’,’
and
“Pathology
Division.
University.
Tokyo
(Received
received
(Accepted
31
Hirohashia
Cancer Center
National
Research
Institute
and
bDepartment
of Surgery,
School
of Medicine.
Keio
(Japan)
10 December
(Revision
S.
molecule in hepatocellular expression in an
22
1990) January
January
1991)
1991)
Summary
Introduction
Expression of E- and P-cadherin in 24 primary hepatocellular carcinomas, together with the non-cancerous liuer tissue from each case, was examined by immunohistochemicai staining. Cells of 23 grade I-111 carcinomas as well as hepatocytes in all the non-cancerous liuers expressed E-cadherin at the cell-cell boundary and showed tight intercellular adhe-
Cadherin is a general term used to describe a type of Ca *+-dependent intercellular adhesion molecule. Cadherins comprise several subclasses and mediate cell to cell binding in a homophilic and subclass-specific manner [ 141. These molecules seem to play an important role in the control of morphogenesis in developing embryos [14] and also in maintaining an orderly structure in differentiated tissues. Epithelial tissues express and use at least two subclasses of cadherin, E- and Pcadherin [12], which are thought to be indispensable for maintenance of structure and function. It is known that cancer cells commonly show decreased intercellular adhesiveness as compared with the corresponding normal epithelial cells [2,7], and that various deficiencies of junctional structures are frequently present in cancers [ 161. The weak intercellular adhesion shown by cancer cells is considered to be responsible for some of their properties, such as invasiveness [3] and metastasis. However, the molecular mechanisms responsible for the decreased intercellular adhesiveness are still unclear. Against this background, we have been studying human cadherin molecules in
sion without
exception.
However,
a highly
un-
differentiated carcinoma classified as grade IV apparently lacked E-cadherin expression and intercellular decreased also showed adhesiveness.
Loss
of E-cadherin
expression
may be one of the characteristics of highly undifferentiated hepatocellular carcinoma. In contrast to E-cadherin, P-cadherin was never detected cancerous
in either the cancer cells hepatocytes in all cases.
Keywords: hepatocellular chemistry
Cancer
to: Y. Shimoyama. Research
0304.3835/91/$03.50 Published
and
non-
cadherin; intercellular adhesion; immunohistocarcinoma;
Correspondence tional
or
Printed
Institute.
cj
1991
in Ireland
Pathology
Tokyo,
Elsevier
Dwision.
Na-
Japan
Scientific
Publishers
Ireland
Ltd
132
2 mM CaQ M phosphate
view of their important implications in the field of cancer research [12,13]. In the present study, we examined cadherin expression in human hepatocellular carcinomas and found a very interesting case in which E-cadherin expression was apparently lacking.
Specimens Fresh specimens of cancerous and noncancerous liver were obtained at surgery from 24 patients with primary hepatocellular carcinomas. Surgery in all cases was carried out at the National Cancer Center Hospital. The specimens were immediately processed for preparation of frozen sections as described previously [12], except that a buffer containing 10 mM HEPES (pH 7.4)) 150 mM NaCl and
immunohistochemical
III carcinomas, tercellular expression
respectively.
adhesion. and
tight
detection Cancer
D is the only intercellular
of E-cadherin
cells in these case
of grade
adhesion.
cases
lmmunohistochemistry and histopathology Immunohistochemistry was performed using frozen sections and avidin-biotin-peroxidase complex as described previously [12], except that frozen sections were mounted on poly Dlysine-coated slides, immersed in 0.3% hydrogen peroxide in absolute methanol at room temperature for 1 h to inhibit en-
in hepatocellular express
IV carcinoma,
Scale
bars
of 0.1
Antibodies Anti-human E- and P-cadherin monoclonal antibodies, designated HECD- 1 and NCCCAD-299, respectively, were used for immunohistochemistry. The establishment and specificity of these antibodies has been reported previously [ 121.
Materials and Methods
Fig. 1.
(HNC) was used instead buffer (pH 7.4).
indicate
E-cadherin and 100
carcinomas.
is composed pm.
A, B and
at the cell-cell of cancer
C are grades
boundary cells lacking
and
show
both
I. II and tight
E-cadherin
in-
133
dogenous peroxidase activity and HNC was used instead of phosphate-buffered saline (pH 7.4) containing 1 mM CaCI,. A serial section from each case was stained with hematoxylin and eosin for histopathological grading. Hepatocellular carcinomas were graded to I-IV according to Edmondson and Steiner [4] Results
Twenty-four primary hepatocellular carcinomas as well as the surrounding noncancerous liver tissue in each case were examined for E- and P-cadherin expression immunohistochemically. Among the hepatocellular carcinomas, 5 were grade I, 12 grade II, 6 grade III and one grade IV. Among the
non-cancerous liver specimens, 11 showed cirrhosis, 2 precirrhosis, 9 chronic hepatitis and 2 liver fibrosis. Cancer cells in 23 grade I-III hepatocellular carcinomas and the corresponding non-cancerous hepatocytes expressed Ecadherin at the cell-cell boundary and showed tight intercellular adhesion without exception (Fig. 1, A-C). However, in the only case of grade IV carcinoma, E-cadherin was not detected in the cancer cells, and intercellular contact appeared to be loose in comparison with that of cancer cells in other carcinomas and non-cancerous hepatocytes (Fig. 1D and Also in this case, non-cancerous 2). hepatocytes surrounding the carcinoma expressed E-cadherin and formed tight intercellular adhesion as did other cancer cells and non-cancerous hepatocytes. P-cadherin
Fig. 2. Histopathological appearance of the grade IV hepatocellular carcinoma. A section of the carcinoma shown in Fig. 1D was cut from a routinely formalin-fixed and paraffin-embedded block. and then stained with hematoxylin and eosin. This figure shows coexistence of grade III (left side) and grade IV (right side) carcinoma. convincing us that the carcinoma on the right was undoubtedly hepatocellular carcinoma. Since grade IV was predominant, this case was diagnosed as grade IV hepatocellular carcinoma. Note that as compared with the grade III carcinoma, the grade IV carcinoma consisted of small cancer cells lacking tight intercellular adhesion. Unfortunately, information about E-cadherin expression in the area of grade III carcinoma was unknown, because the frozen section of this case used for immunohistochemistry did not contain it. Scale bar indicates 100 pm.
134
was never detected in either the cancer cells or non-cancerous hepatocytes in all cases (data not shown), as in normal hepatocytes [12]. Discussion
We reported previously that normal human hepatocytes expressed E-cadherin and possibly used it as a major Ca’+-dependent intercellular adhesion molecule [ 121. Similarly, cancer cells in 23 out of the 24 present hepatocellular carcinomas, as well as hepatocytes in all the non-cancerous livers showing cirrhosis, chronic hepatitis or fibrosis, also expressed Ecadherin and showed tight intercellular adhesion. However, one highly undifferentiated hepatocellular carcinoma did not express Ecadherin and did not exhibit tight intercellular adhesion. These findings suggest that the loss of E-cadherin expression in this carcinoma was the reason for the loose intercellular adhesion. To date, loss of an intercellular adhesion molecule in hepatocellular carcinoma has been reported only for cell-CAM 105 [5], which is involved in the intercellular adhesion of several simple epithelia including hepatocytes in a Ca*+ -independent manner [lO,ll]. That report described that cell-CAM 105 was lost in all of 13 rat hepatocellular carcinomas examined. However, since decreased intercellular adhesion was observed in only 3 of the carcinomas, for which information about Ecadherin was unavailable, it remained uncertain whether the loss of cell-CAM 105 had influenced intercellular adhesion in these cases. We recently demonstrated the frequent occurrence of allele loss at the haptoglobin locus on chromosome 16q22 [8] in hepatocellular carcinoma, and its close relationship to a poorly differentiated histopathology and metastatic ability of hepatocellular carcinoma [ 15,171. On the other hand, uvomorulin, which is identical to E-cadherin, has been mapped to chromosome 16921.1, just adjacent to the haptoglobin locus [6,9]. In this context, it is very interesting that the present hepatocellular carcinoma which lacked E-cadherin expression undifferentiated showed most the histopathological appearance. Using restriction
fragment length polymorphism analysis, we confirmed that this carcinoma had lost a long arm of chromosome 16 (H. Tsuda and S. Hirohashi, unpublished observation). Taking these findings together, there is a possibility that some mutation at or near the E-cadherin gene on the other allele might have been the cause of the loss of E-cadherin expression in the present grade IV carcinoma. We are now attempting to verify this possibility using a molecular biological approach, and also to determine whether a tumor suppressor gene involved in hepatocellular carcinogenesis exists near the haptoglobin and E-cadherin loci. It has been supposed that decreased intercellular adhesiveness of cancer cells caused by reduction of cadherin function might facilitate their invasion to surrounding tissues [l] and metastasis to distant organs. Thus it is very interesting to know the clinical course of the patient with the grade IV carcinoma. In fact, although any apparent metastasis was not detected at surgery, metastases in residual liver and lung were clinically found only 4 months after the hepatectomy, suggesting an exceedingly progressive nature of the carcinoma. How decreased intercellular adhesion affects the biological behavior of cancer cells is another important issue to be clarified in the future. Acknowledgement
We thank Drs. M. Sakamoto, H. Tsuda, M. Makuuchi, S. Yamasaki and H. Hasegawa for supplying the surgical specimens. We also thank Mr. S. Osaka for photographic work. This work was supported in part by a Grant-inAid from the Ministry of Health and Welfare of Japan for a Comprehensive lo-Year Strategy for Cancer Control. Y. Shimoyama is an awardee of a Research Resident Fellowship from the Foundation for Promotion of Cancer Research. References 1
Behrens. chmeier.
J . Mareel. W. (1989)
M.M., Van Roy, Dissecting tumor
F.M. and BP eel1 Invasion:
135
6
9
epithelial cells acquire invasive properties after the loss of uvomorulin-mediated cell-cell adhesion. J. Cell Biol., 108. 2435-2447. Coman, D.R. (1944) Decreased mutual adhesiveness, a property of cells from squamous cell carcinomas. Cancer Res., 4, 625-629. Coman. D.R. (1947) Mechanism of the invasiveness of cancer. Science, 105. 347-348. Edmondson, H.A. and Steiner, P.E. (1954) Primary carcinoma of the liver: a study of 100 cases among 48,900
10
necropsies. Cancer, 7, 462-503. Hixon, D.C., McEntire. K.D. and iibrink, B. (1985) Alterations in the expression of a hepatocyte cell adhesion molecule by transplantable rat hepatocellular carcinomas. Cancer Res., 45, 3742-3749. Mansouri, A., Spurr, N., Goodfellow. P.N. and Kemler, R. (1988) Characterization and chromosomal localization of the gene encoding the human cell adhesion molecule uvomorulin. Differentiation, 38, 67-71. McCutcheon, M., Coman, D.R. and Moore, F.B. (1948) Adhesiveness of malignant cells in various human adenocarcinomas. Cancer, 1, 460-467. McGill, J.R., Yang, Y., Baldwin, W.D.. Brune, J.L., Barnett, D.R., Bowman, B.H. and Moore, C.M. (1984) Localization of the haptoglobin Q and 0 genes (HPA and HPB) to human chromosome 16q22 by in situ hybridization. Cytogenet. Cell Genet., 38, 155-157. Natt, E., Magenis. R.E.. Zimmer, J., Mansouri, A. and Scherer. G. (1989) Regional assignment of the human loci for uvomorulin (UVO) and chymotrypsinogen B (CTRB) with the help of two overlapping deletions on the long arm of chromosome 16. Cytogenet. Cell Genet.. 50, 145- 148.
13
11
12
14
15
16
17
obrink,
B. (1986) Epithelial cell adhesion
molecules.
Exp.
Cell Res., 163, 1-21. Ocklind, C. and dbrink, B. (1982) Intercellular adhesion of rat hepatocytes: identification of a cell surface glycoprotein involved in the initial adhesion process. J. Biol. Chem.. 257, 6788-6795. Shimoyama, Y., Hirohashi, S., Hirano, S., Noguchi. M., Shimosato, Y., Takeichi, M. and Abe, 0. (1989) Cadherin cell-adhesion molecules in human epithelial tissues and carcinomas. Cancer Res., 49, 2128-2133. Shimoyama, Y., Yoshida, T., Terada, M., Shimosato, Y., Abe, 0. and Hirohashi, S. (1989) Molecular cloning of a human Ca’+-dependent cell-cell adhesion molecule homologous to mouse placental cadherin: its low expression in human placental tissues. J. Cell Biol., 109, 1787-1794. Takeichi, M. (1988) The cadherins: cell-cell adhesion molecules controlling animal morphogenesis. Development, 102. 639-655. Tsuda, H., Zhang, W., Shimosato, Y., Yokota. J., Terada, M., Sugimura, T., Miyamura, T. and Hirohashi, S. (1990) Allele loss on chromosome 16 associated with progression of human hepatocellular carcinoma. Proc. Natl. Acad. Sci. U.S.A., 87, 6791-6794. Weinstein, R.S., Merk, F.B. and Alroy, J. (1976) The structure and function of intercellular junctions in cancer. Adv. Cancer Res.. 23, 23-89. Zhang, W., Hirohashi, S., Tsuda. H., Shimosato, Y.. Yokota, J., Terada, M. and Sugimura. T. (1990) Frequent loss of heterozygosity on chromosomes 16 and 4 in human hepatocellular carcinoma. Jpn. J. Cancer Res., 81. 108-111.
Letters.
Elsevier
57 (1991)
Scientific
131
131-135
Publishers
Ireland
Ltd.
Cadherin intercellular adhesion carcinomas: loss of E-cadherin undifferentiated carcinoma Y.
Shirnoyarna’,’
and
“Pathology
Division.
University.
Tokyo
(Received
received
(Accepted
31
Hirohashia
Cancer Center
National
Research
Institute
and
bDepartment
of Surgery,
School
of Medicine.
Keio
(Japan)
10 December
(Revision
S.
molecule in hepatocellular expression in an
22
1990) January
January
1991)
1991)
Summary
Introduction
Expression of E- and P-cadherin in 24 primary hepatocellular carcinomas, together with the non-cancerous liuer tissue from each case, was examined by immunohistochemicai staining. Cells of 23 grade I-111 carcinomas as well as hepatocytes in all the non-cancerous liuers expressed E-cadherin at the cell-cell boundary and showed tight intercellular adhe-
Cadherin is a general term used to describe a type of Ca *+-dependent intercellular adhesion molecule. Cadherins comprise several subclasses and mediate cell to cell binding in a homophilic and subclass-specific manner [ 141. These molecules seem to play an important role in the control of morphogenesis in developing embryos [14] and also in maintaining an orderly structure in differentiated tissues. Epithelial tissues express and use at least two subclasses of cadherin, E- and Pcadherin [12], which are thought to be indispensable for maintenance of structure and function. It is known that cancer cells commonly show decreased intercellular adhesiveness as compared with the corresponding normal epithelial cells [2,7], and that various deficiencies of junctional structures are frequently present in cancers [ 161. The weak intercellular adhesion shown by cancer cells is considered to be responsible for some of their properties, such as invasiveness [3] and metastasis. However, the molecular mechanisms responsible for the decreased intercellular adhesiveness are still unclear. Against this background, we have been studying human cadherin molecules in
sion without
exception.
However,
a highly
un-
differentiated carcinoma classified as grade IV apparently lacked E-cadherin expression and intercellular decreased also showed adhesiveness.
Loss
of E-cadherin
expression
may be one of the characteristics of highly undifferentiated hepatocellular carcinoma. In contrast to E-cadherin, P-cadherin was never detected cancerous
in either the cancer cells hepatocytes in all cases.
Keywords: hepatocellular chemistry
Cancer
to: Y. Shimoyama. Research
0304.3835/91/$03.50 Published
and
non-
cadherin; intercellular adhesion; immunohistocarcinoma;
Correspondence tional
or
Printed
Institute.
cj
1991
in Ireland
Pathology
Tokyo,
Elsevier
Dwision.
Na-
Japan
Scientific
Publishers
Ireland
Ltd
132
2 mM CaQ M phosphate
view of their important implications in the field of cancer research [12,13]. In the present study, we examined cadherin expression in human hepatocellular carcinomas and found a very interesting case in which E-cadherin expression was apparently lacking.
Specimens Fresh specimens of cancerous and noncancerous liver were obtained at surgery from 24 patients with primary hepatocellular carcinomas. Surgery in all cases was carried out at the National Cancer Center Hospital. The specimens were immediately processed for preparation of frozen sections as described previously [12], except that a buffer containing 10 mM HEPES (pH 7.4)) 150 mM NaCl and
immunohistochemical
III carcinomas, tercellular expression
respectively.
adhesion. and
tight
detection Cancer
D is the only intercellular
of E-cadherin
cells in these case
of grade
adhesion.
cases
lmmunohistochemistry and histopathology Immunohistochemistry was performed using frozen sections and avidin-biotin-peroxidase complex as described previously [12], except that frozen sections were mounted on poly Dlysine-coated slides, immersed in 0.3% hydrogen peroxide in absolute methanol at room temperature for 1 h to inhibit en-
in hepatocellular express
IV carcinoma,
Scale
bars
of 0.1
Antibodies Anti-human E- and P-cadherin monoclonal antibodies, designated HECD- 1 and NCCCAD-299, respectively, were used for immunohistochemistry. The establishment and specificity of these antibodies has been reported previously [ 121.
Materials and Methods
Fig. 1.
(HNC) was used instead buffer (pH 7.4).
indicate
E-cadherin and 100
carcinomas.
is composed pm.
A, B and
at the cell-cell of cancer
C are grades
boundary cells lacking
and
show
both
I. II and tight
E-cadherin
in-
133
dogenous peroxidase activity and HNC was used instead of phosphate-buffered saline (pH 7.4) containing 1 mM CaCI,. A serial section from each case was stained with hematoxylin and eosin for histopathological grading. Hepatocellular carcinomas were graded to I-IV according to Edmondson and Steiner [4] Results
Twenty-four primary hepatocellular carcinomas as well as the surrounding noncancerous liver tissue in each case were examined for E- and P-cadherin expression immunohistochemically. Among the hepatocellular carcinomas, 5 were grade I, 12 grade II, 6 grade III and one grade IV. Among the
non-cancerous liver specimens, 11 showed cirrhosis, 2 precirrhosis, 9 chronic hepatitis and 2 liver fibrosis. Cancer cells in 23 grade I-III hepatocellular carcinomas and the corresponding non-cancerous hepatocytes expressed Ecadherin at the cell-cell boundary and showed tight intercellular adhesion without exception (Fig. 1, A-C). However, in the only case of grade IV carcinoma, E-cadherin was not detected in the cancer cells, and intercellular contact appeared to be loose in comparison with that of cancer cells in other carcinomas and non-cancerous hepatocytes (Fig. 1D and Also in this case, non-cancerous 2). hepatocytes surrounding the carcinoma expressed E-cadherin and formed tight intercellular adhesion as did other cancer cells and non-cancerous hepatocytes. P-cadherin
Fig. 2. Histopathological appearance of the grade IV hepatocellular carcinoma. A section of the carcinoma shown in Fig. 1D was cut from a routinely formalin-fixed and paraffin-embedded block. and then stained with hematoxylin and eosin. This figure shows coexistence of grade III (left side) and grade IV (right side) carcinoma. convincing us that the carcinoma on the right was undoubtedly hepatocellular carcinoma. Since grade IV was predominant, this case was diagnosed as grade IV hepatocellular carcinoma. Note that as compared with the grade III carcinoma, the grade IV carcinoma consisted of small cancer cells lacking tight intercellular adhesion. Unfortunately, information about E-cadherin expression in the area of grade III carcinoma was unknown, because the frozen section of this case used for immunohistochemistry did not contain it. Scale bar indicates 100 pm.
134
was never detected in either the cancer cells or non-cancerous hepatocytes in all cases (data not shown), as in normal hepatocytes [12]. Discussion
We reported previously that normal human hepatocytes expressed E-cadherin and possibly used it as a major Ca’+-dependent intercellular adhesion molecule [ 121. Similarly, cancer cells in 23 out of the 24 present hepatocellular carcinomas, as well as hepatocytes in all the non-cancerous livers showing cirrhosis, chronic hepatitis or fibrosis, also expressed Ecadherin and showed tight intercellular adhesion. However, one highly undifferentiated hepatocellular carcinoma did not express Ecadherin and did not exhibit tight intercellular adhesion. These findings suggest that the loss of E-cadherin expression in this carcinoma was the reason for the loose intercellular adhesion. To date, loss of an intercellular adhesion molecule in hepatocellular carcinoma has been reported only for cell-CAM 105 [5], which is involved in the intercellular adhesion of several simple epithelia including hepatocytes in a Ca*+ -independent manner [lO,ll]. That report described that cell-CAM 105 was lost in all of 13 rat hepatocellular carcinomas examined. However, since decreased intercellular adhesion was observed in only 3 of the carcinomas, for which information about Ecadherin was unavailable, it remained uncertain whether the loss of cell-CAM 105 had influenced intercellular adhesion in these cases. We recently demonstrated the frequent occurrence of allele loss at the haptoglobin locus on chromosome 16q22 [8] in hepatocellular carcinoma, and its close relationship to a poorly differentiated histopathology and metastatic ability of hepatocellular carcinoma [ 15,171. On the other hand, uvomorulin, which is identical to E-cadherin, has been mapped to chromosome 16921.1, just adjacent to the haptoglobin locus [6,9]. In this context, it is very interesting that the present hepatocellular carcinoma which lacked E-cadherin expression undifferentiated showed most the histopathological appearance. Using restriction
fragment length polymorphism analysis, we confirmed that this carcinoma had lost a long arm of chromosome 16 (H. Tsuda and S. Hirohashi, unpublished observation). Taking these findings together, there is a possibility that some mutation at or near the E-cadherin gene on the other allele might have been the cause of the loss of E-cadherin expression in the present grade IV carcinoma. We are now attempting to verify this possibility using a molecular biological approach, and also to determine whether a tumor suppressor gene involved in hepatocellular carcinogenesis exists near the haptoglobin and E-cadherin loci. It has been supposed that decreased intercellular adhesiveness of cancer cells caused by reduction of cadherin function might facilitate their invasion to surrounding tissues [l] and metastasis to distant organs. Thus it is very interesting to know the clinical course of the patient with the grade IV carcinoma. In fact, although any apparent metastasis was not detected at surgery, metastases in residual liver and lung were clinically found only 4 months after the hepatectomy, suggesting an exceedingly progressive nature of the carcinoma. How decreased intercellular adhesion affects the biological behavior of cancer cells is another important issue to be clarified in the future. Acknowledgement
We thank Drs. M. Sakamoto, H. Tsuda, M. Makuuchi, S. Yamasaki and H. Hasegawa for supplying the surgical specimens. We also thank Mr. S. Osaka for photographic work. This work was supported in part by a Grant-inAid from the Ministry of Health and Welfare of Japan for a Comprehensive lo-Year Strategy for Cancer Control. Y. Shimoyama is an awardee of a Research Resident Fellowship from the Foundation for Promotion of Cancer Research. References 1
Behrens. chmeier.
J . Mareel. W. (1989)
M.M., Van Roy, Dissecting tumor
F.M. and BP eel1 Invasion:
135
6
9
epithelial cells acquire invasive properties after the loss of uvomorulin-mediated cell-cell adhesion. J. Cell Biol., 108. 2435-2447. Coman, D.R. (1944) Decreased mutual adhesiveness, a property of cells from squamous cell carcinomas. Cancer Res., 4, 625-629. Coman. D.R. (1947) Mechanism of the invasiveness of cancer. Science, 105. 347-348. Edmondson, H.A. and Steiner, P.E. (1954) Primary carcinoma of the liver: a study of 100 cases among 48,900
10
necropsies. Cancer, 7, 462-503. Hixon, D.C., McEntire. K.D. and iibrink, B. (1985) Alterations in the expression of a hepatocyte cell adhesion molecule by transplantable rat hepatocellular carcinomas. Cancer Res., 45, 3742-3749. Mansouri, A., Spurr, N., Goodfellow. P.N. and Kemler, R. (1988) Characterization and chromosomal localization of the gene encoding the human cell adhesion molecule uvomorulin. Differentiation, 38, 67-71. McCutcheon, M., Coman, D.R. and Moore, F.B. (1948) Adhesiveness of malignant cells in various human adenocarcinomas. Cancer, 1, 460-467. McGill, J.R., Yang, Y., Baldwin, W.D.. Brune, J.L., Barnett, D.R., Bowman, B.H. and Moore, C.M. (1984) Localization of the haptoglobin Q and 0 genes (HPA and HPB) to human chromosome 16q22 by in situ hybridization. Cytogenet. Cell Genet., 38, 155-157. Natt, E., Magenis. R.E.. Zimmer, J., Mansouri, A. and Scherer. G. (1989) Regional assignment of the human loci for uvomorulin (UVO) and chymotrypsinogen B (CTRB) with the help of two overlapping deletions on the long arm of chromosome 16. Cytogenet. Cell Genet.. 50, 145- 148.
13
11
12
14
15
16
17
obrink,
B. (1986) Epithelial cell adhesion
molecules.
Exp.
Cell Res., 163, 1-21. Ocklind, C. and dbrink, B. (1982) Intercellular adhesion of rat hepatocytes: identification of a cell surface glycoprotein involved in the initial adhesion process. J. Biol. Chem.. 257, 6788-6795. Shimoyama, Y., Hirohashi, S., Hirano, S., Noguchi. M., Shimosato, Y., Takeichi, M. and Abe, 0. (1989) Cadherin cell-adhesion molecules in human epithelial tissues and carcinomas. Cancer Res., 49, 2128-2133. Shimoyama, Y., Yoshida, T., Terada, M., Shimosato, Y., Abe, 0. and Hirohashi, S. (1989) Molecular cloning of a human Ca’+-dependent cell-cell adhesion molecule homologous to mouse placental cadherin: its low expression in human placental tissues. J. Cell Biol., 109, 1787-1794. Takeichi, M. (1988) The cadherins: cell-cell adhesion molecules controlling animal morphogenesis. Development, 102. 639-655. Tsuda, H., Zhang, W., Shimosato, Y., Yokota. J., Terada, M., Sugimura, T., Miyamura, T. and Hirohashi, S. (1990) Allele loss on chromosome 16 associated with progression of human hepatocellular carcinoma. Proc. Natl. Acad. Sci. U.S.A., 87, 6791-6794. Weinstein, R.S., Merk, F.B. and Alroy, J. (1976) The structure and function of intercellular junctions in cancer. Adv. Cancer Res.. 23, 23-89. Zhang, W., Hirohashi, S., Tsuda. H., Shimosato, Y.. Yokota, J., Terada, M. and Sugimura. T. (1990) Frequent loss of heterozygosity on chromosomes 16 and 4 in human hepatocellular carcinoma. Jpn. J. Cancer Res., 81. 108-111.
