A 47-year-old woman has a tumor that is causing symptoms of excessive hormone production. Surgical resection of the lesion is performed with no operative complications, and the neoplastic tissue is subjected to detailed pathologic studies. Electron microscopy reveals the tumor cells have highly developed, smooth endoplasmic reticulum. Which of the following is a possible direct effect of the substance secreted by these cells?

Question

A 47-year-old woman has a tumor that is causing symptoms of excessive hormone production.  Surgical resection of the lesion is performed with no operative complications, and the neoplastic tissue is subjected to detailed pathologic studies.  Electron microscopy reveals the tumor cells have highly developed, smooth endoplasmic reticulum.  Which of the following is a possible direct effect of the substance secreted by these cells?

Quizplus · Accepted Answer

11ec160b_36cf_773f_9249_f75420d580a8_MD0001_00 The endoplasmic reticulum (ER) is an interconnected, membrane-bound network found in almost all eukaryotic cells. It is highly metabolically active and plays a significant role in the synthesis and modification of cellular components. The ER is recognizable on electron microscopy as a flattened tubular or laminar structure near or adjacent to the nucleus. The smooth endoplasmic reticulum (SER) is involved in the synthesis and processing of hydrophobic compounds, including lipids, phospholipids, and cholesterol derivatives (eg, steroid hormones). Cholesterol is initially converted to pregnenolone in the mitochondria and then transferred to the SER, where the remaining steps of steroidogenesis occur. The SER contains the enzymes (eg, 21-hydroxylase) required for steroid and phospholipid biosynthesis. Steroid-producing cells (in the adrenals, gonads, and liver) characteristically contain a well-developed SER. This patient is likely experiencing virilization due to an androgen-secreting ovarian or adrenal tumor. Paraneoplastic syndromes can also occur due to overproduction of other sex steroids, cortisol (ie, Cushing syndrome), or aldosterone. By contrast, the rough endoplasmic reticulum (RER) is characterized by numerous ribosomes on the outer membrane. The RER plays an important role in the synthesis and modification of targeted proteins, including secretable polypeptide hormones. Some of the clinically significant syndromes due to overproduction of peptide hormones by the RER include: Educational objective: The initial step in the synthesis of steroid hormones is the conversion of cholesterol to pregnenolone in the mitochondria. The remainder of steroidogenesis occurs in the smooth endoplasmic reticulum. Steroid-producing cells contain a well-developed smooth endoplasmic reticulum. __________ References: The endoplasmic reticulum: structure, function and response to cellular signaling. (http://www.ncbi.nlm.nih.gov/pubmed/26433683)

A 47-Year-Old Woman Has a Tumor That Is Causing Symptoms