Ectopic Expression of Bone Sialoprotein in Human Thyroid Cancer

Abstract

Bone sialoprotein (BSP) is a small, highly posttranslationally modified integrin binding protein found in the mineral compartment of developing bone. The recent discovery that BSP can be detected in a variety of human cancers, particularly those that metastasize preferentially to the skeleton, shed light on potential new biological functions for this protein. The demonstration of a positive association between BSP expression in primary breast tumors and the development of bone metastases suggests that this glycoprotein could play a role in the selective implantation of breast cancer cells in bone. BSP is also expressed in most lung and prostate cancers as well as in multiple myeloma, three other osteotropic malignancies. Because thyroid carcinoma also metastasizes preferentially to the skeleton, we decided to look at the expression of BSP in a collection of 145 thyroid malignant lesions including 24 follicular thyroid carcinomas (FTCs), 55 papillary thyroid carcinomas (PTCs), 19 medullary thyroid carcinomas (MTCs), 23 anaplastic carcinomas (ACs), and 24 poorly differentiated carcinomas (PDCs). BSP expression was evaluated by immunoperoxidase technique using two specific polyclonal antibodies. Most of the thyroid carcinomas (72%) examined expressed high levels of BSP. Expression of BSP was significantly lower in FTCs and MTCs compared with PDCs, which are more aggressive (p = 0.0009 and 0.0003, respectively). Our study demonstrates for the first time that ectopic BSP expression is a common feature of thyroid cancer. The prognostic value of BSP detection in thyroid adenocarcinoma and the potential role of BSP in the propension of this type of cancer to metastasize to bone are currently under investigation.

Bone Sialoprotein Mediates the Tumor Cell–Targeted Prometastatic Activity of Transforming Growth Factor β in a Mouse Model of Breast Cancer

“…In addition to its role in bone physiology, osteopontin has recently been implicated as an important player in metastasis to multiple sites (32,33) but Bsp is less well studied in this regard. However, a large body of clinical data shows that Bsp protein is overexpressed by many malignant tissues, including breast (34)(35)(36)(37)(38)(39). Serum levels of Bsp are increased in ) were inoculated into tail vein of BALB/c mice.…”

Small Integrin Binding Ligand N -Linked Glycoprotein Gene Family Expression in Different Cancers

“…The expression of other SIBLING members in cancer has not been extensively studied. BSP expression was been reported in breast (4,5), prostate (6), lung (7), and thyroid cancer (8). DMP1 has been shown to be strongly up-regulated in lung cancer (9).…”

Fibroblast growth factor 2 regulates bone sialoprotein gene transcription in human breast cancer cells

“…The relationship between BSP and FGF2 may be relevant to the expression of BSP in tumors. In addition to production by osteogenic tumors, BSP is also expressed in breast, lung, thyroid and prostate cancers (26)(27)(28)32,33). The expression of BSP in human primary breast cancers has been associated with an increased risk CGTTTCTTGTTTATgaAACTGAGCCTGTGT -129) (lane 10) oligonucleotides.…”