Hormonal regulation of cholesterol 7 alpha-hydroxylase specific activity, mRNA levels, and transcriptional activity in vivo in the rat
bile-acid biosynthesis; Biochemistry & Molecular Biology; cholesterol; cholesterol 7 alpha-hydroxylase; cultures; gene; gene cyp7; glucocorticoid; hepatic cholesterol; hepatocyte cultures; liver; messenger-rna levels; monolayer-cultures; primary; protein-kinase-c; regulation; sterol 27-hydroxylase; thyroid; thyroid-hormone
In primary cultures of rat hepatocytes, transcription of the cholesterol 7 alpha-hydroxylase gene is induced synergistically by glucocorticoid and thyroid hormones. The objective of the present study was to evaluate the role of glucocorticoid and thyroid hormones in the maintenance of cholesterol 7 alpha-hydroxylase gene expression in vivo. Male Sprague-Dawley rats underwent adrenalectomy (A), thyroidectomy (T), adrenalectomy + thyroidectomy (A + T), hypophysectomy (H), or sham surgery (paired controls). Ten days post surgery, livers were harvested and cholesterol 7 alpha-hydroxylase specific activity, steady-state mRNA levels, and transcriptional activity were determined. Serum corticosterone levels were <2% of paired controls in A, A + T and H rats. Free thyroxine index was <32% of paired controls in rats with T and H. When compared to sham-operated controls, A + T and H led to decreases in cholesterol 7 alpha-hydroxylase specific activities of 44 +/- 8% and 57 +/- 3%, respectively (P < 0.03 and < 0.05). Similar changes were observed in cholesterol 7 alpha-hyroxylase steady-state mRNA levels, which decreased by 43 +/- 10% (P < 0.001) and 56 +/- 19% (P < 0.05), respectively. Cholesterol 7 alpha-hydroxylase transcriptional activity in A + T and H rats decreased by 34 +/- 11% (P < 0.01) and 61 +/- 4% (P < 0.001), respectively. The observed decreases were greater after H than after A + T, suggesting the possibility that another pituitary hormone plays a role in regulation of cholesterol 7 alpha-hydroxylase. Thyroidectomy alone led to a decrease in cholesterol 7 alpha-hydroxylase specific activity of 37 +/- 7% (P < 0.05) and a trend toward decreased steady-state mRNA levels (21 +/- 12%; P = ns). Adrenalectomy did not significantly decrease cholesterol 7 alpha-hydroxylase specific activity or mRNA levels. Neither thyroidectomy nor adrenalectomy alone affected transcriptional activity. We conclude that under physiologic circumstances, full expression of the cholesterol 7 alpha-hydroxylase gene requires synergistic action of glucocorticoids and thyroid hormone.
Pandak W M; Heuman D M; Redford K; Stravitz R T; Chiang J Y L; Hylemon P B; Vlahcevic Z R
Journal of Lipid Research
1997
1997-12
Journal Article
n/a
Primary Squamous Cell Carcinoma of the Thyroid: A Case Report and Literature Review About a Rare Entity
Primary squamous cell carcinoma of the thyroid (PSCCT) is a rare tumor of the thyroid gland with a higher rate of incidence in females in their fifth and sixth decades of life [1]. The condition is associated with a very poor prognosis and has a five-year overall survival (OS) rate of only 17.7% [2]. It usually presents as a rapidly enlarging anterior neck mass. Other common symptoms include dyspnea, dysphagia, and voice changes [3]. The diagnosis of PSCCT is usually challenging, and ruling out metastasis from other primary sites is mandatory for a proper diagnosis; hence, immunohistochemistry is of crucial importance. There is very limited data in the literature to guide treatment and appropriate follow-up [4].
Primary squamous cell carcinoma of the thyroid (PSCCT) is a rare and aggressive neoplasm that accounts for less than 1% of all thyroid malignancies. Its incidence is higher in females in their fifth and sixth decades of life. The pathophysiology of PSCCT is still a subject of debate as squamous cells are generally absent in the thyroid gland under normal physiologic conditions. Immunohistochemistry is important for reaching a definite diagnosis as it helps to differentiate PSCCT from metastases from other primary sites. Clinically, PSCCT usually presents as a rapidly enlarging anterior neck mass. Surgical resection is the mainstay of treatment despite the lack of any standard guidelines for the same given the rarity of the disease. Adjuvant chemotherapy, radiotherapy, and targeted therapy continue to be of unclear benefit. We report a case of PSSCT in a male patient who presented with a rapidly enlarging neck mass.
Soror NN; Shah P; Hemrock L; Bennett R
Cureus
2021
2021-05-11
Journal Article
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