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Late developing mammary tumors and hyperplasia induced by a low-oncogenic variant of mouse mammary tumor virus (MMTV) express genes identical to those induced by canonical MMTV.

Bruno RD, Rosenfield SM, Smith GH - Mol. Cancer (2013)

Bottom Line: Pro-viral insertions of C3H-MMTV into genomic DNA results in the overexpression of common core insertion site (CIS) genes, including Wnt1/10b, Rspo2, and Fgf3.We confirmed the presence of active virus in Mtv-1/NIV infected tissues and using quantitative reverse transcription PCR (qRT-PCR) found that Mtv-1/NIV induced neoplasms (tumors and hyperplasia) commonly expressed the core CIS genes Wnt1, Wnt10b, Rspo2, Fgf3.These results underscore the importance of core CIS gene expression in the early events leading to MMTV-induced mammary tumor initiation regardless of the viral variant.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: The canonical milk-transmitted mouse mammary tumor virus (MMTV) of C3H mice (C3H-MMTV) rapidly induces tumors in 90% of infected animals by 8 months of age. Pro-viral insertions of C3H-MMTV into genomic DNA results in the overexpression of common core insertion site (CIS) genes, including Wnt1/10b, Rspo2, and Fgf3. Conversely, infection by either the endogenous Mtv-1 virus (in C3Hf) or the exogenous nodule-inducing virus (NIV) (in Balb/c NIV) induces premalignant mammary lesions and tumors with reduced incidence and longer latency than C3H-MMTV. Here, we asked whether Mtv-1/NIV affected the expression of core CIS genes.

Findings: We confirmed the presence of active virus in Mtv-1/NIV infected tissues and using quantitative reverse transcription PCR (qRT-PCR) found that Mtv-1/NIV induced neoplasms (tumors and hyperplasia) commonly expressed the core CIS genes Wnt1, Wnt10b, Rspo2, Fgf3.

Conclusions: These results underscore the importance of core CIS gene expression in the early events leading to MMTV-induced mammary tumor initiation regardless of the viral variant.

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Detection of the Mtv-1/NIV virus in Balb/c NIV mammary tumors. (A) PCR amplification of a 3.0 Kb fragment from genomic DNA isolated from mammary tumors and liver tissues by Polymerase Chain Reaction (PCR) with MMTV (C3H)-specific primers. The MMTV (C3H) 3.0 Kb PCR product was detected in DNA isolated from Balb/c NIV mammary tumors, C3Hf mammary tumors and C3Hf liver tissue (positive controls) but not in Balb/c liver. Primers designed to the region 12918–1303 of Chromosome 1 were used as a loading control and to confirm genomic DNA quality. (B and C) Electron micrographs of ultrathin sections taken from mammary tumors of a C3H (MMTV) (B) and C3Hf (NIV) (C) mice show the presence of B-type retrovirions are abundant in both tumor types. Micrographs were taken of representative viral particles from ultrathin sections of OSO4 (osmium teroxide)-fixed tumor tissues, which had been stained with uranyl acetate and lead citrate to enhanced their electron density. The micrographs were taken on a Philips 300 electron microscope equipped with a camera. Scale bars = 200 nm.
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Figure 1: Detection of the Mtv-1/NIV virus in Balb/c NIV mammary tumors. (A) PCR amplification of a 3.0 Kb fragment from genomic DNA isolated from mammary tumors and liver tissues by Polymerase Chain Reaction (PCR) with MMTV (C3H)-specific primers. The MMTV (C3H) 3.0 Kb PCR product was detected in DNA isolated from Balb/c NIV mammary tumors, C3Hf mammary tumors and C3Hf liver tissue (positive controls) but not in Balb/c liver. Primers designed to the region 12918–1303 of Chromosome 1 were used as a loading control and to confirm genomic DNA quality. (B and C) Electron micrographs of ultrathin sections taken from mammary tumors of a C3H (MMTV) (B) and C3Hf (NIV) (C) mice show the presence of B-type retrovirions are abundant in both tumor types. Micrographs were taken of representative viral particles from ultrathin sections of OSO4 (osmium teroxide)-fixed tumor tissues, which had been stained with uranyl acetate and lead citrate to enhanced their electron density. The micrographs were taken on a Philips 300 electron microscope equipped with a camera. Scale bars = 200 nm.

Mentions: To determine if the low oncogenic viruses Mtv-1/NIV affected these same core CIS genes, we analyzed mammary hyperplasia and tumors in C3Hf and Balb/c NIV mice. All mice were housed in Association and Accreditation of Laboratory Animal Care-accredited facilities in accordance with the NIH Guide for the Care and Use of Laboratory Animals. The National Cancer Institute Animal Care and Use Committee approved all experimental procedure. Breeding pairs of Balb/c NIV mice were a kind gift from Lawrence Young. From these pairs, we established a colony, and consistent with his findings, we identified tumors in only 39 out of 102 (38%) retired Balb/c NIV breeders, and never before the second year of life. From these mice, we transplanted suspected hyperplastic tissue and established 5 independent Balb/c NIV hyperplastic outgrowth (HOG) lines (Table 1). C3Hf tumors were collected from the Heston colony [3]. We confirmed the presence of virus by PCR with a primer set that identifies C3H-MMTV and Mtv-1/NIV, but not endogenous MMTV present within the Balb/c genome (Figure 1A) [12]. Genomic DNA samples isolated from Balb/c mammary tumors induced by MMTV from Czech mice, which is unrelated to C3H-MMTV, were also negative when tested with this primer set (data not shown). Ultrathin sections from mammary tumors of Balb/c NIV, C3Hf, and C3H mice were examined under an electron microscope. Intracellular nucleocapsids, budding forms, and extracellular retrovirions of the B type were found abundantly in both tumor types (Figure 1B and C). Comparison of the viral particles found in canonical milk-borne MMTV-infected C3H mammary tumors and those in tumors from C3Hf and Balb/c NIV and C3H-MMTV were indistinguishable.


Late developing mammary tumors and hyperplasia induced by a low-oncogenic variant of mouse mammary tumor virus (MMTV) express genes identical to those induced by canonical MMTV.

Bruno RD, Rosenfield SM, Smith GH - Mol. Cancer (2013)

Detection of the Mtv-1/NIV virus in Balb/c NIV mammary tumors. (A) PCR amplification of a 3.0 Kb fragment from genomic DNA isolated from mammary tumors and liver tissues by Polymerase Chain Reaction (PCR) with MMTV (C3H)-specific primers. The MMTV (C3H) 3.0 Kb PCR product was detected in DNA isolated from Balb/c NIV mammary tumors, C3Hf mammary tumors and C3Hf liver tissue (positive controls) but not in Balb/c liver. Primers designed to the region 12918–1303 of Chromosome 1 were used as a loading control and to confirm genomic DNA quality. (B and C) Electron micrographs of ultrathin sections taken from mammary tumors of a C3H (MMTV) (B) and C3Hf (NIV) (C) mice show the presence of B-type retrovirions are abundant in both tumor types. Micrographs were taken of representative viral particles from ultrathin sections of OSO4 (osmium teroxide)-fixed tumor tissues, which had been stained with uranyl acetate and lead citrate to enhanced their electron density. The micrographs were taken on a Philips 300 electron microscope equipped with a camera. Scale bars = 200 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 1: Detection of the Mtv-1/NIV virus in Balb/c NIV mammary tumors. (A) PCR amplification of a 3.0 Kb fragment from genomic DNA isolated from mammary tumors and liver tissues by Polymerase Chain Reaction (PCR) with MMTV (C3H)-specific primers. The MMTV (C3H) 3.0 Kb PCR product was detected in DNA isolated from Balb/c NIV mammary tumors, C3Hf mammary tumors and C3Hf liver tissue (positive controls) but not in Balb/c liver. Primers designed to the region 12918–1303 of Chromosome 1 were used as a loading control and to confirm genomic DNA quality. (B and C) Electron micrographs of ultrathin sections taken from mammary tumors of a C3H (MMTV) (B) and C3Hf (NIV) (C) mice show the presence of B-type retrovirions are abundant in both tumor types. Micrographs were taken of representative viral particles from ultrathin sections of OSO4 (osmium teroxide)-fixed tumor tissues, which had been stained with uranyl acetate and lead citrate to enhanced their electron density. The micrographs were taken on a Philips 300 electron microscope equipped with a camera. Scale bars = 200 nm.
Mentions: To determine if the low oncogenic viruses Mtv-1/NIV affected these same core CIS genes, we analyzed mammary hyperplasia and tumors in C3Hf and Balb/c NIV mice. All mice were housed in Association and Accreditation of Laboratory Animal Care-accredited facilities in accordance with the NIH Guide for the Care and Use of Laboratory Animals. The National Cancer Institute Animal Care and Use Committee approved all experimental procedure. Breeding pairs of Balb/c NIV mice were a kind gift from Lawrence Young. From these pairs, we established a colony, and consistent with his findings, we identified tumors in only 39 out of 102 (38%) retired Balb/c NIV breeders, and never before the second year of life. From these mice, we transplanted suspected hyperplastic tissue and established 5 independent Balb/c NIV hyperplastic outgrowth (HOG) lines (Table 1). C3Hf tumors were collected from the Heston colony [3]. We confirmed the presence of virus by PCR with a primer set that identifies C3H-MMTV and Mtv-1/NIV, but not endogenous MMTV present within the Balb/c genome (Figure 1A) [12]. Genomic DNA samples isolated from Balb/c mammary tumors induced by MMTV from Czech mice, which is unrelated to C3H-MMTV, were also negative when tested with this primer set (data not shown). Ultrathin sections from mammary tumors of Balb/c NIV, C3Hf, and C3H mice were examined under an electron microscope. Intracellular nucleocapsids, budding forms, and extracellular retrovirions of the B type were found abundantly in both tumor types (Figure 1B and C). Comparison of the viral particles found in canonical milk-borne MMTV-infected C3H mammary tumors and those in tumors from C3Hf and Balb/c NIV and C3H-MMTV were indistinguishable.

Bottom Line: Pro-viral insertions of C3H-MMTV into genomic DNA results in the overexpression of common core insertion site (CIS) genes, including Wnt1/10b, Rspo2, and Fgf3.We confirmed the presence of active virus in Mtv-1/NIV infected tissues and using quantitative reverse transcription PCR (qRT-PCR) found that Mtv-1/NIV induced neoplasms (tumors and hyperplasia) commonly expressed the core CIS genes Wnt1, Wnt10b, Rspo2, Fgf3.These results underscore the importance of core CIS gene expression in the early events leading to MMTV-induced mammary tumor initiation regardless of the viral variant.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: The canonical milk-transmitted mouse mammary tumor virus (MMTV) of C3H mice (C3H-MMTV) rapidly induces tumors in 90% of infected animals by 8 months of age. Pro-viral insertions of C3H-MMTV into genomic DNA results in the overexpression of common core insertion site (CIS) genes, including Wnt1/10b, Rspo2, and Fgf3. Conversely, infection by either the endogenous Mtv-1 virus (in C3Hf) or the exogenous nodule-inducing virus (NIV) (in Balb/c NIV) induces premalignant mammary lesions and tumors with reduced incidence and longer latency than C3H-MMTV. Here, we asked whether Mtv-1/NIV affected the expression of core CIS genes.

Findings: We confirmed the presence of active virus in Mtv-1/NIV infected tissues and using quantitative reverse transcription PCR (qRT-PCR) found that Mtv-1/NIV induced neoplasms (tumors and hyperplasia) commonly expressed the core CIS genes Wnt1, Wnt10b, Rspo2, Fgf3.

Conclusions: These results underscore the importance of core CIS gene expression in the early events leading to MMTV-induced mammary tumor initiation regardless of the viral variant.

Show MeSH
Related in: MedlinePlus