Biochemical and Immunohistochemical Characterization of the Amyloid in Canine Amyloid-Producing Odontogenic Tumor

Abstract

The amyloid of canine amyloid-producing odontogenic tumor (APOT) was evaluated biochemically and immunohistochemically. The N-terminal amino-acid sequence of purified amyloid protein from a canine APOT was strikingly similar to the sequence in both rat ameloblastin and porcine sheathlin. Immunohistochemically, the amyloid in APOT from 9 dogs was strongly reactive with anti-rat ameloblastin, anti-porcine sheathlin, and anti-canine APOT amyloid and weakly reactive with anti-porcine amelogenin but negative for antibodies to cytokeratins, vimentin, desmin, a-smooth muscle actin, amyloid A, glial fibrillary acidic protein, or S100 protein. The neoplastic epithelial cells of APOT were focally reactive with antibodies to ameloblastin, sheathlin, amelogenin, and canine APOT amyloid. The similarity in amino-acid sequence of the amyloid protein of canine APOT to that of enamel proteins, such as ameloblastin, sheathlin, and amelogenin, and the expression of these antigens in both APOT amyloid and in the neoplastic cells suggest that the amyloid of canine APOT is derived from enamel proteins secreted by ameloblasts. Keywords ameloblasts, amyloid, dogs, enamel proteins, odontogenic tumorAmyloidosis is a heterogeneous group of disorders characterized by the deposition of amyloid proteins derived from any of at least 25 different precursor molecules. Amyloid is considered a pathologic substance that appears histologically as an extracellular, amorphous, congophilic protein with applegreen birefringence under polarized light. Amyloidosis can be categorized as systemic or localized. Common human types of localized amyloidosis include amyloidosis of endocrine organs associated (or not) with neoplastic conditions and cerebral amyloidosis of Alzheimer's disease. 21,51 Localized amyloid deposits with or without association with neoplasia also have been described in the human mammary gland, 41,52 respiratory tract, 26,34 gastrointestinal tract, 5,38 genitourinary tract, 13,17 skin, 24,25 and bone. 23 In animals, localized amyloidosis has been associated with neoplastic conditions such as calcifying epithelial odontogenic tumor (CEOT), 2,29 pancreatic endocrine tumor, 28 medullary thyroid carcinoma, 15 ameloblastoma, 10 mammary carcinoma, 43 intestinal carcinoid, 40 extramedullary plasmacytoma, 31,36 and myeloma. 12 CEOT is a rare neoplasm of the tooth-forming apparatus that produces a mineralized substance and amyloid. 30 The origin of the amyloid in human and animal CEOT is often debated but is still unknown. 2,19,27,29,37,42,46 Recent studies indicate that the amyloid in human CEOT is secreted by the neoplastic epithelial cells, but its precise nature remains unclear. 27,39,42 CEOT in veterinary medicine is classified as amyloidproducing odontogenic tumor (APOT). 9,14 In the present study, we partially sequenced the amino acids of the major amyloid protein of canine APOT and compared the amino-terminal sequence with that of the enamel proteins rat ameloblastin and porcine sheathlin, which are transcribed in cells of the epi...

Immunohistochemical and Biochemical Evidence of Ameloblastic Origin of Amyloid-Producing Odontogenic Tumors in Cats

“…Neoplastic epithelial cells and amyloid from the canine APOTs, as well as the immature enamel matrix and ameloblast cytoplasm from the canine fetal teeth, all were immunoreactive to rat ameloblastin, porcine amelogenin and sheathlin, and an anticanine APOT amyloid-specific polyclonal antibody developed for the study. 6 The neoplastic cells were also positive for CK AE1/AE3, CK9, and CK14. 6 The neoplastic epithelium of the feline APOTs in this study was immunoreactive to some epithelial-specific antibodies, including CK AE1/AE3, CK14, and CK19, in addition to human ameloblastin.…”

“…6 The neoplastic cells were also positive for CK AE1/AE3, CK9, and CK14. 6 The neoplastic epithelium of the feline APOTs in this study was immunoreactive to some epithelial-specific antibodies, including CK AE1/AE3, CK14, and CK19, in addition to human ameloblastin. However, neither the amyloid nor the neoplastic epithelium of the feline APOTS had immunoreactivity for amelogenin.…”

“…4 The presence of an ameloblastin peptide in these feline APOTs is consistent with the finding of a similar enamel protein in an APOT from a Shih Tzu dog, in which the amyloid, analyzed via SDS-PAGE, was composed of an NH 2 -terminal amino acid sequence similar to both rat ameloblastin and porcine sheathlin. 6 In that study, the APOTs from the Shih Tzu and 8 other dogs, as well as developing teeth from 3 canine fetuses, were characterized immunohistochemically. Neoplastic epithelial cells and amyloid from the canine APOTs, as well as the immature enamel matrix and ameloblast cytoplasm from the canine fetal teeth, all were immunoreactive to rat ameloblastin, porcine amelogenin and sheathlin, and an anticanine APOT amyloid-specific polyclonal antibody developed for the study.…”

Amyloid-Producing Odontogenic Tumors of the Facial Skin in Three Cats

“…4 Biochemical and immunohistochemical examination of canine APOT revealed that the amyloid proteins in the neoplasm are composed of enamel protein lineage (such as ameloblastin, amelogenin and sheathlin) secreted by neoplastic ameloblasts. 5 In addition, the neoplastic epithelial cells express enamel proteins. 5 The neoplastic epithelial cells and intratumoral amyloid are considered to be of ameloblastic lineage in canine and feline APOTs.…”

The Binding of Curcumin to Various Types of Canine Amyloid Proteins

“…In the present study, we examined the binding of curcumin to various amyloid proteins in canine, such as AA, AL, amyloid of canine amyloid-producing odontogenic ameloblast-associated tumor [3,11], and senile cardiovascular amyloid [10]. Furthermore, the change of binding ability to amyloid by KMnO 4 treatment was also examined [12,13].…”