Breast Tumor Microcalcification Induced by Bone Morphogenetic Protein-2: A New Murine Model for Human Breast Tumor Diagnosis.

Asghar Hajibeigi,Robert E Lenkinski,Kien Nham,Khaled Nasr,Durga Udayakumar

doi:10.1155/2018/2082154

Asghar Hajibeigi, Robert E Lenkinski + Show 3 more

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https://doi.org/10.1155/2018/2082154

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Abstract

Widespread use of screening mammography has recently increased the detection of breast microcalcifications. These nonpalpable microcalcifications with specific features in breast tissues are clinically considered an early indicator of breast carcinoma. Our goal in this study was to develop a murine breast microcalcification model for optimizing in vivo imaging. Recombinant human BMP-2 was expressed in E. coli, and the purified bioactive protein was used as inducing factor for the production of breast microcalcifications in a murine animal model. Syngeneic breast tumors were obtained by injection of MDA-MB-231 human breast cancer cells with Matrigel into the mammary fat pad of female nude mice. Different doses of bioactive rhBMP-2 were administered either as single or multiple intraperitoneal injections or directly into tumor on a weekly basis. Three weeks after the first injection of rhBMP-2, the microcalcification of breast tumor was detected by microcomputed tomography followed by intravenous injection of radiotracer [18F] Sodium fluoride for positron emission tomography imaging. Our findings indicate that rhBMP-2 induced microcalcifications of breast tumor by both systemic and direct injection of rhBMP-2 into tumors in a dose-dependent manner. Although little is known about the molecular mechanism of microcalcification, here we report a new murine model of human breast tumor induced microcalcification by rhBMP-2 to optimize in vivo imaging methods and to study the role of BMP-2 as a mediator of pathological mineralization and bone-like microcalcification formation in breast tumor. This BMP-2-induced microcalcification model may allow us to discriminate the type of microcalcification in tumors and to perform quantitative analysis on the calcification as a new detection strategy for early identification of pathological mineralization of breast tissues in women.

Highlights

Breast cancer is a disease of high prevalence among women in the western and industrialized countries
After 72 h of treatment with rhBMP-2, the C2C12 revealed a significant increase of alkaline phosphatase induction (ALP) in both positive control and experimentally purified protein in treated C2C12 cell lysates (Figure 1(c)) as well as in colorimetric detected assay in culture plate (Figure 1(d))
Our results indicate that nude mice with syngeneic human breast tumors that received rhBMP-2 either by IP injection or direct intratumoral injection exhibited microcalcifications detected by CT. e induction of microcalcifications by rhBMP-2 in this study was consistent with the previously results reported by Liu et al that showed that rhBMP-2 induced microcalcification in a syngeneic rat breast tumor model [14]

Summary

Introduction

Breast cancer is a disease of high prevalence among women in the western and industrialized countries. It represents 15% of all new cancer cases in the US [1]. Up to 50% of all nonpalpable breast cancers are detected solely through microcalci cations observed on mammography, and up to 93% of cases of ductal carcinoma in situ (DCIS) present with microcalci cations [4]. Haka et al [5] applied Raman spectroscopy to analyze the chemical composition of microcalci cations occurring in benign and malignant lesions in the human breast and identi ed two major types of microcalci cations. Type I, calcium oxalate dihydrate crystals are seen most frequently in benign ductal cysts and are rarely found in foci of carcinoma, whereas the type II calcium phosphate deposits

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