Transforming growth factor-β1 induces growth inhibition of a human medullary thyroid carcinoma cell line despite an increase in steady state c- myc messenger ribonucleic acid levels

Sundeep Khosla, Merry Jo Oursler, M. J. Schroeder, N. L. Eberhardt

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Abstract

Medullary thyroid cancer (MTC) is an endocrine tumor of the thyroid C- cells which provides an important experimental model for studies of tumor differentiation and progression. We investigated the effects of transforming growth factor-β1 (TGFβ1) on the growth and functional characteristics of a human medullary thyroid carcinoma cell line (TT). Because the c-myc protooncogene may play an important role in the growth inhibition induced by TGFβ1, we also assessed steady state c-myc messenger RNA (mRNA) levels in these cells. A 6-day exposure of TT cells to TGFβ1 resulted in a dose- dependent inhibition of cell proliferation. In addition, TGFβ1 exposure led to a 3-fold increase in nonadherent floating TT cells in the culture supernatants. The floating cells exhibited ultrastructural features of dying or apoptotic cells, including chromatin condensation, cytoplasmic and nuclear vesicularization, and DNA degradation with evidence of internucleosomal DNA 'laddering.' Despite inhibition of cell proliferation, steady state c-myc mRNA levels were 3.6 ± 0.6-fold higher in cells exposed to TGFβ1 compared to those in control cells (P < 0.001). Exposure of cells to a 15-base antisense c-myc oligonucleotide (10 μM) resulted in an attenuation of the TGFβ1-induced growth inhibition and induction of cell death. TGFβ1 also resulted in an approximately 3-fold decrease in steady state calcitonin and calcitonin gene-related peptide mRNA levels. Finally, using a sensitive bioassay for TGFβ, TT cells were shown to produce and activate significant amounts of TGFβ, particularly under conditions of serum deprivation. Our data thus indicate that TGFβ1 has multiple effects on TT cell growth and function. It induces growth inhibition in the presence of an increase in steady state mRNA levels of the c-myc protooncogene, which is usually associated with cell proliferation. In addition, TGFβ1 accelerates apoptosis in TT cells.

Original languageEnglish (US)
Pages (from-to)1887-1893
Number of pages7
JournalEndocrinology
Volume135
Issue number5
DOIs
StatePublished - 1994

Fingerprint

Transforming Growth Factors
RNA
Cell Line
Growth
Messenger RNA
Cell Proliferation
Medullary Thyroid cancer
Calcitonin Gene-Related Peptide
DNA
Calcitonin
Oligonucleotides
Biological Assay
Chromatin
Neoplasms
Thyroid Gland
Cell Death
Theoretical Models
Cell Culture Techniques
Apoptosis

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

@article{61347b1289844ccfb6f4374aff1e94c7,
title = "Transforming growth factor-β1 induces growth inhibition of a human medullary thyroid carcinoma cell line despite an increase in steady state c- myc messenger ribonucleic acid levels",
abstract = "Medullary thyroid cancer (MTC) is an endocrine tumor of the thyroid C- cells which provides an important experimental model for studies of tumor differentiation and progression. We investigated the effects of transforming growth factor-β1 (TGFβ1) on the growth and functional characteristics of a human medullary thyroid carcinoma cell line (TT). Because the c-myc protooncogene may play an important role in the growth inhibition induced by TGFβ1, we also assessed steady state c-myc messenger RNA (mRNA) levels in these cells. A 6-day exposure of TT cells to TGFβ1 resulted in a dose- dependent inhibition of cell proliferation. In addition, TGFβ1 exposure led to a 3-fold increase in nonadherent floating TT cells in the culture supernatants. The floating cells exhibited ultrastructural features of dying or apoptotic cells, including chromatin condensation, cytoplasmic and nuclear vesicularization, and DNA degradation with evidence of internucleosomal DNA 'laddering.' Despite inhibition of cell proliferation, steady state c-myc mRNA levels were 3.6 ± 0.6-fold higher in cells exposed to TGFβ1 compared to those in control cells (P < 0.001). Exposure of cells to a 15-base antisense c-myc oligonucleotide (10 μM) resulted in an attenuation of the TGFβ1-induced growth inhibition and induction of cell death. TGFβ1 also resulted in an approximately 3-fold decrease in steady state calcitonin and calcitonin gene-related peptide mRNA levels. Finally, using a sensitive bioassay for TGFβ, TT cells were shown to produce and activate significant amounts of TGFβ, particularly under conditions of serum deprivation. Our data thus indicate that TGFβ1 has multiple effects on TT cell growth and function. It induces growth inhibition in the presence of an increase in steady state mRNA levels of the c-myc protooncogene, which is usually associated with cell proliferation. In addition, TGFβ1 accelerates apoptosis in TT cells.",
author = "Sundeep Khosla and Oursler, {Merry Jo} and Schroeder, {M. J.} and Eberhardt, {N. L.}",
year = "1994",
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T1 - Transforming growth factor-β1 induces growth inhibition of a human medullary thyroid carcinoma cell line despite an increase in steady state c- myc messenger ribonucleic acid levels

AU - Khosla, Sundeep

AU - Oursler, Merry Jo

AU - Schroeder, M. J.

AU - Eberhardt, N. L.

PY - 1994

Y1 - 1994

N2 - Medullary thyroid cancer (MTC) is an endocrine tumor of the thyroid C- cells which provides an important experimental model for studies of tumor differentiation and progression. We investigated the effects of transforming growth factor-β1 (TGFβ1) on the growth and functional characteristics of a human medullary thyroid carcinoma cell line (TT). Because the c-myc protooncogene may play an important role in the growth inhibition induced by TGFβ1, we also assessed steady state c-myc messenger RNA (mRNA) levels in these cells. A 6-day exposure of TT cells to TGFβ1 resulted in a dose- dependent inhibition of cell proliferation. In addition, TGFβ1 exposure led to a 3-fold increase in nonadherent floating TT cells in the culture supernatants. The floating cells exhibited ultrastructural features of dying or apoptotic cells, including chromatin condensation, cytoplasmic and nuclear vesicularization, and DNA degradation with evidence of internucleosomal DNA 'laddering.' Despite inhibition of cell proliferation, steady state c-myc mRNA levels were 3.6 ± 0.6-fold higher in cells exposed to TGFβ1 compared to those in control cells (P < 0.001). Exposure of cells to a 15-base antisense c-myc oligonucleotide (10 μM) resulted in an attenuation of the TGFβ1-induced growth inhibition and induction of cell death. TGFβ1 also resulted in an approximately 3-fold decrease in steady state calcitonin and calcitonin gene-related peptide mRNA levels. Finally, using a sensitive bioassay for TGFβ, TT cells were shown to produce and activate significant amounts of TGFβ, particularly under conditions of serum deprivation. Our data thus indicate that TGFβ1 has multiple effects on TT cell growth and function. It induces growth inhibition in the presence of an increase in steady state mRNA levels of the c-myc protooncogene, which is usually associated with cell proliferation. In addition, TGFβ1 accelerates apoptosis in TT cells.

AB - Medullary thyroid cancer (MTC) is an endocrine tumor of the thyroid C- cells which provides an important experimental model for studies of tumor differentiation and progression. We investigated the effects of transforming growth factor-β1 (TGFβ1) on the growth and functional characteristics of a human medullary thyroid carcinoma cell line (TT). Because the c-myc protooncogene may play an important role in the growth inhibition induced by TGFβ1, we also assessed steady state c-myc messenger RNA (mRNA) levels in these cells. A 6-day exposure of TT cells to TGFβ1 resulted in a dose- dependent inhibition of cell proliferation. In addition, TGFβ1 exposure led to a 3-fold increase in nonadherent floating TT cells in the culture supernatants. The floating cells exhibited ultrastructural features of dying or apoptotic cells, including chromatin condensation, cytoplasmic and nuclear vesicularization, and DNA degradation with evidence of internucleosomal DNA 'laddering.' Despite inhibition of cell proliferation, steady state c-myc mRNA levels were 3.6 ± 0.6-fold higher in cells exposed to TGFβ1 compared to those in control cells (P < 0.001). Exposure of cells to a 15-base antisense c-myc oligonucleotide (10 μM) resulted in an attenuation of the TGFβ1-induced growth inhibition and induction of cell death. TGFβ1 also resulted in an approximately 3-fold decrease in steady state calcitonin and calcitonin gene-related peptide mRNA levels. Finally, using a sensitive bioassay for TGFβ, TT cells were shown to produce and activate significant amounts of TGFβ, particularly under conditions of serum deprivation. Our data thus indicate that TGFβ1 has multiple effects on TT cell growth and function. It induces growth inhibition in the presence of an increase in steady state mRNA levels of the c-myc protooncogene, which is usually associated with cell proliferation. In addition, TGFβ1 accelerates apoptosis in TT cells.

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