Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

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Chapter | 25 Tumor Markers
the periodic acid Schiff reaction. However, immunohistochemical
staining allows specific and sensitive evaluation
of the integrity of the basement membrane, facilitating
the distinction between benign tumors with intact basement
membranes and invasive cancers with degraded basement
membranes (Peña et al. , 1995) . Fragmentation, loss,
or absence of the basement membrane is associated with
tumor invasion and metastasis in human colorectal cancer
(Ogawa et al. , 2005) . Immunostaining with antibodies
directed against matrix metalloproteinase enzymes (e.g.,
MMP-9), which degrade basement membrane proteins,
may also be important for understanding the relationship
between the extracellular matrix and cancer progression
(Yokota et al. , 2001) .
8 . Integrins
The integrins mediate cell-to-cell adhesions and play a role
in interactions between cells and the extracellular matrix
proteins including fibronectin, collagens, and laminin.
Decreased expression of integrins correlates with the metastatic
potential of the tumor (Kawaguchi, 2005) . Expression
of other integrins, such as alpha(v)beta3, may reflect the
angiogenic activity of the tumor, as has been observed
in canine melanoma (Rawlings et al. , 2003) .
9 . Amyloid
Antibodies, directed against amyloid of immunoglobulin
lambda light-chain origin and amyloid-A, have been used
to confirm that the amyloid associated with plasma cell
tumors is of immunoglobulin origin (Cangul et al. , 2002) .
These immunoreactivity patterns have also been useful to
show plasmacytoid differentiation in some tumors.
10 . Oncoproteins
Antibodies directed against proteins of oncogenes or tumor
suppressor genes may serve as biomarkers for cancer.
Antibodies have been developed against human p53, Rb,
PTEN, Bcl-2, BCRA1, c- myc , c- ras , and c- erbB -2, among
others; reports in the veterinary literature suggest crossreactivity
with some of them to domestic animal tissues. In
canine lymphoma, expression of the p53 protein is associated
with high-grade histology and the T cell immunophenotype
( Sueiro et al. , 2004 ), both of which suggest a poor
prognosis. Likewise, overexpression of the p53 protein was
associated with a poor prognosis for dogs with mammary
gland tumors ( Lee et al. , 2004 ). Changes in expression of
PTEN and p53 proteins have been associated with canine
melanoma ( Koenig et al. , 2002 ). The expression Bcl-2, a
regulator of apoptosis, did not predict survival in a study
of feline lymphoma ( Dank et al. , 2002 ). Overexpression of
c- ras has been associated with the development of feline
hyperthyroidism ( Merryman et al. , 1999 ).
VI. CYTOCHEMISTRY
Light microscopy of blood films and bone marrow aspirate
specimens has been aided by cytochemistry to distinguish
various hematological disorders, most notably the acute leukemias.
Although various new techniques, including immunophenotyping,
various molecular methods ( Grindem, 1996 ),
and flow cytometry ( Fernandes et al. , 2002 ), are improving
the classification of these diseases, cytological evaluation
remains an integral part of diagnosis. The myeloperoxidase
reaction and Sudan black C stain are useful for identifying
neutrophilic differentiation, along with chloroacetate esterase.
In the dog and cat, acute myeloid leukemia can be diagnosed
on the basis of alkaline phosphatase reactivity because
their normal neutrophils lack alkaline phosphatase reactivity.
The “ nonspecific ” esterase reactions, including α-naphthyl
acetate esterase, are useful for identifying monocytic differentiation.
The lipase stain can also be a marker for monocytic
differentiation. Acute monoblastic leukemia has been diagnosed
in the dog based on reactivity with N-butyrate esterase
and the lack of chloroacetate esterase or leukocyte peroxidase
reactivity ( Modiano et al. , 1998 ). Myelomonocytic leukemias
can be recognized by simultaneous cytochemical reactivity,
often alkaline phosphatase and nonspecific esterase ( Jain
et al. , 1981 ). Basophilic leukemia has been reported to be negative
for peroxidase and naphthol AS-D chloroacetate esterase
reactivity ( Mahaffey et al. , 1987 ). Cytochemical evaluation
of acute megakaryoblastic leukemia may be of limited
diagnostic value ( Colbatzky and Hermanns, 1993 ). Similar
cytochemical techniques have also been applied to lymph
node samples, both imprint and aspirate, to distinguish B and
T cell regions and cell types ( Raskin and Nipper, 1992 ).
VII. CYTOGENETICS
Cytogenetics refers to both the study of the structure of
chromosome material and the study of diseases caused by
structural and numerical abnormalities of chromosomes.
It includes the routine analysis of G-banded chromosomes,
other cytogenetic banding techniques, and molecular cytogenetics
such as fluorescent in situ hybridization (FISH)
and comparative genomic hybridization (CGH). In human
medicine, cytogenetics has played an important role in
the diagnosis and clinical management of lymphomas,
leukemias, and various solid tumors ( Campbell, 2005 ;
Gebhart, 2004 ; Mundle and Sokolova, 2004 ). Breakthroughs
in karyotype analysis have overcome the impediments presented
by the complexity of the canine karyotype (2N 78 )
in identifying rearranged chromosomes ( Milne et al. ,
2004 ). Both numerical and structural chromosome abnormalities
have been identified in canine soft tissue sarcomas
( Milne et al. , 2004 ). Although many of the cytogenetic
studies of animal tumors have been small case series, the
advent and development of microarrays for canine CGH