Parathyroid carcinoma occurred in two glands in multiple endocrine neoplasia 1: a report on a rare case.

Primary hyperparathyroidism is the most common hormonal manifestation associated with multiple endocrine neoplasia 1 (MEN1). It is generally caused by parathyroid hyperplasia, and parathyroid carcinoma is rare. Here, we report a case of MEN1 with parathyroid carcinoma in two parathyroid glands causing primary hyperparathyroidism. A 40-year-old man with primary hyperparathyroidism due to MEN1 underwent a total parathyroidectomy. His corrected calcium and intact PTH (i-PTH) serum levels were 10.8 mg/dL and 203 pg/mL, respectively. Although three glands were successfully removed, the left upper parathyroid gland could not be detected. Since the right lower parathyroid lesion had invaded into the thyroid, right lobectomy was performed. A portion of the left lower parathyroid tissue was transplanted into his forearm. The histological findings of the left lower and the right upper parathyroid glands were consistent with hyperplasia while that of the right lower parathyroid gland was parathyroid carcinoma. Since the post-surgical i-PTH levels remained high, the intrathyroidal lesion of the left lobe, which was initally diagnosed as an adenomatous nodule, was suspected to contain parathyroid tumor. A fine needle aspiration of the tumor revealed a high concentration of i-PTH. One week after the first surgery, a left thyroid lobectomy was performed. The pathological diagnosis of the tumor was parathyroid carcinoma. After the surgery, calcium and i-PTH levels were normal. Although it is rare, parathyroid carcinoma should be considered as a cause of hyperparathyroidism in MEN1 patients. Since it is difficult to diagnose parathyroid carcinoma before surgery, intraoperative findings are important for the appropriate treatment.

Autocrine parathyroid hormone-like hormone promotes intrahepatic cholangiocarcinoma cell proliferation via increased ERK/JNK-ATF2-cyclinD1 signaling.

BACKGROUND AND AIMS: Intrahepatic cholangiocarcinoma (ICC) is an aggressive tumor with a high fatality rate. It was recently found that parathyroid hormone-like hormone (PTHLH) was frequently overexpressed in ICC compared with non-tumor tissue. This study aimed to elucidate the underlying mechanisms of PTHLH in ICC development. METHODS: The CCK-8 assay, colony formation assays, flow cytometry and a xenograft model were used to examine the role of PTHLH in ICC cells proliferation. Immunohistochemistry (IHC) and western blot assays were used to detect target proteins. Luciferase reporter, chromatin immunoprecipitation (ChIP) and DNA pull-down assays were used to verify the transcription regulation of activating transcription factor-2 (ATF2). RESULTS: PTHLH was significantly upregulated in ICC compared with adjacent and normal tissues. Upregulation of PTHLH indicated a poor pathological differentiation and intrahepatic metastasis. Functional study demonstrated that PTHLH silencing markedly suppressed ICC cells growth, while specific overexpression of PTHLH has the opposite effect. Mechanistically, secreted PTHLH could promote ICC cell growth by activating extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways, and subsequently upregulated ATF2 and cyclinD1 expression. Further study found that the promoter activity of PTHLH were negatively regulated by ATF2, indicating that a negative feedback loop exists. CONCLUSIONS: Our findings demonstrated that the ICC-secreted PTHLH plays a characteristic growth-promoting role through activating the canonical ERK/JNK-ATF2-cyclinD1 signaling pathways in ICC development. We identified a negative feedback loop formed by ATF2 and PTHLH. In this study, we explored the therapeutic implication for ICC patients.

Limited value of long-term biochemical follow-up in patients with adrenal incidentalomas-a retrospective cohort study.

BACKGROUND: The prevailing view that advocates long-term hormonal follow-up of adrenal incidentalomas is currently under debate. The purpose of the present study was to examine all adrenal incidentalomas presented during five years to a single centre. We hypothesized that 24-month biochemical follow-up in patients with an initial normal screening would fail to increase the sensitivity in finding hormone producing tumours. METHODS: The present study is a retrospective register based cohort study of 194 patients referred to the Department of Endocrinology at Södersjukhuset between the years 2006-2010. Computerized medical records were used to find and extract information on patients with newly discovered adrenal incidentalomas. The sensitivity, specificity, positive predictive value and negative predictive value were calculated to evaluate the validity of an initial normal screening when used to identify individuals with hormone producing tumours. RESULTS: Of the incidentalomas 94% consisted of benign, non-functioning tumours. Three patients were diagnosed with cortisol hypersecretion and one with pheochromocytoma. The sensitivity, specificity, positive predictive value and negative predictive value of an initial complete negative screening to predict a hormone producing tumour were 100%, 63%, 12% and 100%, respectively. CONCLUSION: Patients with an initially normal hormonal screening may not need further biochemical follow-up.

No metabolic impact of surgical normalization of hyperandrogenism in postmenopausal women with ovarian androgen-secreting tumours.

AIM: To examine the impact of surgical normalization of testosterone on body weight and on glucose and lipid metabolism and insulin sensitivity in a group of hyperandrogenic women with ovarian androgen-secreting tumours (OAST). METHODS: Five consecutive postmenopausal hyperandrogenic patients (aged 63 ± 5 years) with a diagnosis of OAST were prospectively evaluated. Clinical signs, symptoms and metabolic and hormonal parameters were collected at the time of the diagnosis and at follow-up, 12 months after surgical oophorectomy. A group of 15 age-matched and body mass index-matched postmenopausal control women served as a reference group. RESULTS: At baseline, patients with OAST had very high testosterone levels and inappropriately low gonadotrophin levels for their menopausal status. All the women were overweight or obese, and one had a history of polycystic ovary syndrome and Type 2 diabetes. Twelve months after surgical oophorectomy, testosterone and gonadotrophin levels returned to appropriate values for menopausal status in all patients; however, no change in body weight was found. Fasting glucose levels slightly increased (P < 0·05) without any significant change in other metabolic parameters. In the woman with diabetes, a moderate decrease in haemoglobin A1c occurred. Red blood cell count and haematocrit values were normalized (P < 0·05, respectively). CONCLUSION: Normalization of androgen levels achieved after surgical oophorectomy did not cause any significant change in body weight and insulin sensitivity. These findings may offer a different perspective on the impact of hyperandrogenaemia on metabolism.

An Open-label Phase I/IIa Clinical Trial of 11ß-HSD1 Inhibitor for Cushing's Syndrome and Autonomous Cortisol Secretion.

CONTEXT: 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) inhibitors demonstrate antimetabolic and antisarcopenic effects in Cushing's syndrome (CS) and autonomous cortisol secretion (ACS) patients. OBJECTIVE: To confirm the efficacy and safety of S-707106 (11ß-HSD1 inhibitor) administered to CS and ACS patients. DESIGN: A 24-week single-center, open-label, single-arm, dose-escalation, investigator-initiated clinical trial on a database. SETTING: Kyushu University Hospital, Kurume University Hospital, and related facilities. PATIENTS: Sixteen patients with inoperable or recurrent CS and ACS, with mildly impaired glucose tolerance. INTERVENTION: Oral administration of 200 mg S-707106 after dinner, daily, for 24 weeks. In patients with insufficient improvement in oral glucose tolerance test results at 12 weeks, an escalated dose of S-707106 (200 mg twice daily) was administered for the residual 12 weeks. MAIN OUTCOME MEASURES: The rate of participants responding to glucose tolerance impairment, defined as those showing a 25% reduction in the area under the curve (AUC) of plasma glucose during the 75-g oral glucose tolerance test at 24 weeks. RESULTS: S-707106 administration could not achieve the primary endpoint of this clinical trial (>20% of responsive participants). AUC glucose decreased by -7.1% [SD, 14.8 (90% CI -14.8 to -1.0), P = 0.033] and -2.7% [14.5 (-10.2 to 3.4), P = 0.18] at 12 and 24 weeks, respectively. S-707106 administration decreased AUC glucose significantly in participants with a high body mass index. Body fat percentage decreased by -2.5% [1.7 (-3.3 to -1.8), P < 0.001] and body muscle percentage increased by 2.4% [1.6 (1.7 to 3.1), P < 0.001]. CONCLUSIONS: S-707106 is an effective insulin sensitizer and antisarcopenic and antiobesity medication for these patients.

The Impact of Mild Autonomous Cortisol Secretion on Bone Turnover Markers.

CONTEXT: Several studies have reported increased risk of fragility fractures in patients with mild autonomous cortisol secretion (MACS), discordant to the degree of bone density deterioration. OBJECTIVE: To evaluate the effect of MACS on bone metabolism in patients with adrenal adenomas. DESIGN: Cross-sectional study with prospective enrollment, 2014-2019. SETTING: Referral center. PATIENTS: 213 patients with adrenal adenomas: 22 Cushing syndrome (CS), 92 MACS and 99 nonfunctioning adrenal tumors (NFAT). MAIN OUTCOME MEASURES: Osteocalcin, procollagen I intact N-terminal (PINP), C-terminal telopeptide (CTX), sclerostin. RESULTS: Patients with CS demonstrated lower markers of bone formation compared with patients with MACS and NFAT (CS vs MACS vs NFAT: mean osteocalcin 14.8 vs 20.1 vs 21.3 ng/mL [P < 0.0001]; mean PINP 34.8 vs 48.7 vs 48.5 µg/L [P = 0.003]). Severity of cortisol excess was inversely associated with sclerostin (CS vs MACS vs NFAT: mean sclerostin 419 vs 538 vs 624 ng/L, [P < 0.0001]). In a multivariable model of age, sex, body mass index, cortisol, and bone turnover markers, sclerostin was a significant predictor of low bone mass in patients with MACS (OR 0.63 [CI 95%, 0.40-0.98] for each 100 ng/L of sclerostin increase).After adrenalectomy, osteocalcin, CTX, and sclerostin increased by a mean difference of 6.3 ng/mL, 0.12 ng/mL, and 171 pg/mL (P = 0.02 for all), respectively. CONCLUSIONS: Lower sclerostin level in patients with MACS reflects a reduction in osteocyte function or number associated with exposure to chronic cortisol excess. Increase in bone turnover markers after adrenalectomy suggests restoration of favorable bone metabolism.

[Beta-hCG producing urothelial carcinoma of the urinary bladder: a case report].

A 74-year-old man visited our hospital presenting with pollakisuria. Cystoscopy revealed a bladder cancer with necrotic tissue. The patient was initially treated by transurethral resection of bladder tumor (TUR-Bt). Pathologically, the tumor was shown to be a carcinoma of bladder with human chorionic gonadotropin (hCG) positivity. After TUR-Bt, chemotherapy with M-VAC (methotrexate, vinblastine, adriamycine and cisplatin) was performed. This patient is still alive eight months after resection. To our knowledge, there are 37 cases of beta-hCG-producing urothelial carcinoma of the urinary bladder reported in the Japanese literature.

Hypoglycemia due to paraneoplastic secretion of insulin-like growth factor-I in a patient with metastasizing large-cell carcinoma of the lung.

CONTEXT: Nonpancreatic tumors may cause recurrent hypoglycemia known as nonislet cell tumor hypoglycemia. It is due to overproduction and secretion by the tumor of incompletely processed IGF-II, termed big IGF-II. We recently identified a patient with recurrent hypoglycemia and low insulin, but without elevated big IGF-II. Multiple small lung nodules were detected by computed tomography scan. An undifferentiated large-cell carcinoma was diagnosed from an axillary lymph node metastasis. OBJECTIVE: The objective was to investigate whether the patient's hypoglycemia was due to excessive IGF-I production by the tumor. METHODS: Serum IGF- I and IGF-II, insulin, and GH were measured by RIA; the distribution of IGFs between IGF binding protein complexes in serum was analyzed after neutral gel filtration. Tissue IGF-I was identified by immunohistochemistry and in situ hybridization, and by RT-PCR after RNA extraction. RESULTS: Total and free serum IGF-I, but not total, free, and big IGF-II, was increased, and the IGF-I content of the two IGF binding protein complexes was elevated. Immunohistochemistry demonstrated IGF-I peptide in situ hybridization IGF-I mRNA in the lymph node metastasis. Combined GH/glucocorticoid treatment prevented hypoglycemia, but did not lower IGF-I. After chemotherapy with carboplatinum/etoposide, the lung nodules largely regressed, and serum IGF-I and the IGF-I content of the two binding protein complexes became normal. Hypoglycemia did not recur despite discontinuation of GH/glucocorticoid treatment. CONCLUSION: Our findings are compatible with a new form of tumor hypoglycemia caused by circulating tumor-derived IGF-I.

Nature of the immunoreactive neurophysins in ectopic vasopressin-producing oat cell carcinomas of the lung. Demonstration of a putative common precursor to vasopressin and neurophysin.

In an attempt to delineate the nature of the immunoreactive neurophysins in oat cell carcinomas of the lung with ectopic vasopressin production, tumor neurophysins were characterized by gel filtration and by electrophoresis. In all of the five tumor tissues, activities of both vasopressin and nicotine-stimulated neurophysin (NSN) determined by radioimmunoassay were demonstrated. A small amount of oxytocin as well as estrogen-stimulated neurophysin was detected in three of the tissues. When tissue extract was subjected to Sephadex G-50 gel filtration in 0.2 N acetic acid, the major portion of immunoreactive NSN emerged in the fractions corresponding to the molecular size of 10,000. The migration pattern of NSN in these fractions on electrophoresis was qualitatively the same as that of NSN extracted from human posterior pituitary glands. In addition to this major neurophysin, immunoreactive NSN with the molecular size of 20,000 was consistently demonstrated in three tumor extracts. This high molecular weight form of neurophysin represented 6.5--8.7% of total NSN immunoactivities in each tumor extract and its elution profile was not changed when analyzed under denaturating conditions in 6 M guanidine hydrochloride. On electrophoresis, it migrated near the gamma globulin region; however, the peak was broad suggesting that it consists of more than two different molecular populations. A substantial portion of the high molecular weight NSN appears to be a glycoprotein judging from its binding to concanavalin A. When the high molecular weight from of neurophysin was incubated with trypsin, essentially all of the activities were converted into NSN with the molecular size of 10,000. Moreover, an equimolar amount of vasopressin was liberated after the treatment, the elution pattern of which closely resembled that of synthetic arginine vasopressin. When a lower concentration of trypsin was used, some of the 20,000-dalton neurophysin exhibited activities of both NSN and vasopressin. Since the antivasopressin serum used in this study appeared to be directed toward the ring portion side of vasopressin, these results suggest that this 20,000-dalton neurophysin is, in all probability, a common precursor to vasopressin and neurophysin, and that vasopressin may be located in the middle of the precursor molecule.

Guanosine nucleotides inhibit different syndromes of PTHrP excess caused by human cancers in vivo.

There are two well-described syndromes caused by tumor production of parathyroid hormone-related peptide (PTHrP), namely osteolytic bone disease associated with breast cancer and humoral hypercalcemia of malignancy (HHM) that occurs with or without bone metastasis. Both syndromes have been shown experimentally to be inhibited by neutralizing antibodies to PTHrP. In a search for small-molecule inhibitors of PTHrP production or effects, we have identified guanine-nucleotide analogs as compounds that inhibit PTHrP expression by human tumor cells associated with these syndromes. We show in nude athymic murine models that these compounds reduce PTHrP-mediated osteolytic lesions associated with metastatic human breast-cancer cells as well as the degree of hypercalcemia caused by excessive PTHrP production by a squamous-cell carcinoma of the lung. These results suggest that the PTHrP gene promoter may be a suitable target for treating the skeletal effects of malignancy.

Paraneoplastic endocrine syndromes.

The majority of neoplasms are responsible for symptoms caused by mass effects to surrounding tissues and/or through the development of metastases. However, occasionally neoplasms, with or without endocrine differentiation, acquire the ability to secrete a variety of bioactive substances or induce immune cross-reactivity with the normal tissues that can lead to the development of characteristic clinical syndromes. These syndromes are named endocrine paraneoplastic syndromes when the specific secretory components (hormones, peptides or cytokines) are unrelated to the anticipated tissue or organ of origin. Endocrine paraneoplastic syndromes can complicate the patient's clinical course, response to treatment, impact prognosis and even be confused as metastatic spread. These syndromes can precede, occur concomitantly or present at a later stage of tumour development, and along with the secreted substances constitute the biological 'fingerprint' of the tumour. Their detection can facilitate early diagnosis of the underlying neoplasia, monitor response to treatment and/or detect early recurrences following successful initial management. Although when associated with tumours of low malignant potential they usually do not affect long-term outcome, in cases of highly malignant tumours, endocrine paraneoplastic syndromes are usually associated with poorer survival outcomes. Recent medical advances have not only improved our understanding of paraneoplastic syndrome pathogenesis in general but also enhanced their diagnosis and treatment. Yet, given the rarity of endocrine paraneoplastic syndromes, there is a paucity of prospective clinical trials to guide management. The development of well-designed prospective multicentre trials remains a priority in the field in order to fully characterise these syndromes and provide evidence-based diagnostic and therapeutic protocols.

Estrogen production as a tumor marker in patients with gonadotropin-producing neoplasms.

Urinary estradiol production rates, plasma estradiol, and peripheral conversion of dehydroepiandrosterone sulfate (DHEAS) to estradiol were explored in patients whose neoplasms made human chorionic gonadotropin and/or human chorionic gonadotropin beta fragments. In five men with choriocarcinoma, estradiol production was elevated, plasma estradiol was high, and DHEAS conversion to estradiol ranged from 0.5 to 11.7%. In six patients with "ectopic" gonadotropin-producing tumors, originating from lung, stomach, and liver, estradiol production was elevated to a lesser degree. Sera from 154 of 864 patients (16.8%) with a wide variety of advanced neoplastic disorders were noted to have minimal elevations of human chorionic gonadotropin beta subunit in their sera but had normal luteinizing hormone assays. Plasma estradiol levels in these patients were not elevated, and in only one of ten patients studied was there slight elevation of the estradiol production rate. Similarly, in only one of ten patients was there measurable conversion of DHEAS to estradiol. We conclude that, in patients whose neoplastic disorders are associated with major elevations of human chorionic gonadotropin, there is concordant extragonadal production of estradiol via DHEAS, presumably representing an associated trophoblastic function. However, estrogen production is not a sensitive tumor marker in those patients whose neoplasms are associated with minimal elevations of human chorionic gonadotropin beta fragments only.

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in small-cell lung cancer.

Review of clinical data from 350 patients with small-cell lung cancer (SCLC) revealed hyponatremia (sodium less than 130 mEq/L) attributable to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in 40 patients (11%). Although hyponatremia was severe in most instances (median, sodium 117 mEq/L), symptoms attributable to water intoxication were identified in only 27% of hyponatremic episodes. Development of SIADH showed no correlation with clinical stage, distribution of metastatic sites, sex, or histologic subtype of small-cell carcinoma. SIADH occurred most often with initial presentation (33 of 40), and resolved promptly (less than 3 weeks) with initiation of combination chemotherapy in 80% of evaluable patients. The presence of SIADH did not influence response to chemotherapy or overall survival as an independent variable. However, in five patients profound hyponatremia developed immediately following primary cytotoxic therapy (range, one to five days). Despite initial control of SIADH, dilutional hyponatremia recurred in 70% of patients with tumor progression. Our findings suggest that development of clinically demonstrable SIADH in patients with SCLC is dependent on functional properties of the neoplastic cells, rather than tumor burden or metastatic site. The potential for development of clinically significant hyponatremia early in the course of cytotoxic therapy emphasizes the need to closely monitor patients, particularly those receiving chemotherapy regimens requiring substantial intravenous hydration.

Ectopic parathyroid hormone syndrome. Occurrence in a case undifferentiated lymphoma with bone marrow involvement.

A patient with hypercalcemia, hypophosphatemia, and an undifferentiated lymphoma involving only the bone marrow was treated by us. The finding of an elevated serum parathyroid hormone (PTH) level in the presence of normal parathyroid glands and increased metabolic bone activity on bone biopsy suggests an ectopic PTH syndrome. To our knowledge, no previous case of ectopic PTH syndrome associated with a lymphoma with bone marrow involvement only has been reported.

[Paraneoplastic hormonal syndromes]. / Síndromes hormonales paraneoplásicos.

We can define paraneoplastic syndromes as a combination of effects occurring far from the original location of the tumour and independently from the local repercussion of its metastases. Paraneoplastic hormonal syndromes depend on the secretion of hormonal peptides or their precursors, cytokines and, more rarely, thyroidal hormones and Vitamin D, which act in an endocrine, paracrine or autocrine way. Sometimes, paraneoplastic syndromes can be more serious than the consequences of the primary tumour itself and can precede, develop in parallel, or follow the manifestations of this tumour. It is important to recognise a paraneoplastic hormonal syndrome for several reasons, amongst which we would draw attention to three: 1) It can lead to the diagnosis of a previously undetected, underlying malign or benign neoplasia; 2) It can dominate the clinical picture and thus lead to errors with respect to the origin and type of primary tumour; and 3) It can follow the clinical course of the underlying tumour and thus be useful for monitoring its evolution. The molecular mechanisms responsible for the development of these syndromes are not well-known, but it is believed that they might be inherent to the mutations responsible for the primary tumour or depend on epigenetic factors such as methylation. In this review, we consider the following paraneoplastic hormonal syndromes: malign hypercalcaemia, hyponatraemia (inappropiate secretion of the antidiuretic hormone), ectopic Cushing's syndrome, ectopic acromegaly, hypoglycaemia due to tumours different from those of the islet cells and paraneoplastic gynaecomastia; we make a brief final reference to other hormones (calcitonin, somatostatin, and VIP).

Size heterogeneity of beta-MSH in ectopic ACTH-producing tumors: presence of beta-LPH-like peptide.

Gel chromatographic, immunologic and biologic properties of beta-melanocyte-stimulating hormone (beta-MSH) in tumor tissues obtained from eight patients with the ectopic ACTH syndrome were studied and compared to those of pituitary beta-MSH. Size heterogeneity of immunoreactive beta-MSH was found in all the tumors studied as well as in normal human pituitaries. Both the tumors and pituitaries contained immunoreactive beta-MSH of a larger molecular size than the well-characterized beta-MSH of small molecular size. The large molecular weight beta-MSH also predominated in the plasma. It was found to be bioactive by an in vitro MSH assay, immunologically indistinguishable from human beta-MSH, and chromatographically very similar to beta-lipotropic hormone (beta-LPH). Tryptic digestion of the large molecular weight beta-MSH under controlled conditions promptly produced bioactive beta-MSH of small molecular size, followed by the appearance of immunologically active but biologically inert fragments. These results suggest that the ectopic ACTH-producing tumor as well as the pituitary elaborate beta-LPH-like peptide which might be the predominant component of immunoreactive beta-MSH in man.

Ectopic production of intact parathyroid hormone by a squamous cell lung carcinoma in vivo and in vitro.

Ectopic tumoral production of intact parathyroid hormone (PTH) is rare. The PTH-related protein is the common cause of hypercalcemia in most solid tumors, particularly squamous and renal carcinomas. We report the case of a 71-yr-old man with a PTH-producing squamous cell lung carcinoma. Immunocytochemical analysis of the tumor tissue as well as of cultured tumor cells revealed PTH positive staining. Cultured tumor cells released PTH and were calcium sensitive, producing 122 +/- 16 pg/microgram DNA of intact PTH (mean +/- SEM) at 0.5 mmol/L calcium compared with 26 +/- 2 pg/microgram DNA at 3.0 mmol/L calcium. Somatostatin analogues have been used in the treatment of humoral hypercalcemia of malignancy (HHM). However, we found that somatostatin (0.1 microgram/L) in cultured tumor cells increased the release of intact PTH (123 +/- 19 versus 82 +/- 1 pg/microgram DNA, P < 0.05) and thus might have a negative effect on the HHM. This report is the first to describe a true ectopic PTH-producing squamous cell lung carcinoma associated with HHM.

Ectopic adrenocorticotropin production: disappearance after removal of inflammatory tissue.

A patient presented with the clinical and laboratory features of the ectopic ACTH syndrome. No ACTH-producing tumor was found, and bilateral adrenalectomy was performed to correct the hypercortisolism. Six months later, the removal of a pseudotumor containing only fat and inflammatory tissue resulted in normalization of both basal plasma ACTH levels and the ACTH feedback response to cortisol infusion. It is suggested that the leukocytes in the inflammatory tissue were the source of the ectopic ACTH production.

Expression of neurotensin in endocrine tumors.

Endocrine tumors are useful sources for determining the synthesis and metabolism of secreted regulatory peptides. The present study was performed to compare the synthesis and metabolism of neurotensin (NT) in normal subjects and four patients with NT-producing tumors. NT mRNA was measured and characterized using oligonucleotide probes and Northern blots, while NT-like peptides were quantitated by RIA with region-specific antisera and high pressure liquid chromatography. Northern blot analysis of mRNA isolated from normal human ileum revealed two species of mRNA hybridizing to a heterologous canine oligonucleotide probe; the apparent sizes of the mRNA were 1.4 and 1.0 kilobases. An identical pattern was found in a pancreatic endocrine tumor, a prostatic adenocarcinoma, and a fibrolamellar hepatoma. The ratio of mRNA to peptide varied between the different tissues. For instance, the hepatoma was the richest source of NT mRNA, but the prostatic tumor contained the highest peptide concentration. Measurements with region-specific antisera showed that N-terminal immunoreactive fragments were more abundant than C-terminal fragments in pancreatic, prostatic, and carcinoid tumors (N/C-teminal ratios, 4.0, 1.6, and 5.0) and in equal concentrations in normal ileum. Reverse phase high pressure liquid chromatography revealed the presence of intact NT in addition to a variable number of smaller N-terminal peptides, presumed to be metabolites. In contrast the hepatoma contained a 5-fold excess of C-terminal immunoreactivity. The excess C-terminal immunoreactivity was also present in the circulation of this patient. The chromatographic properties, immunoreactivity, and unusual stability of the C-terminal fragment found in the hepatoma patient suggest that it is a substance distinct from NT itself and is released specifically by the fibrolamellar hepatoma.

Insulin receptor proliferation: a mechanism for tumor-associated hypoglycemia.

A 30-yr-old man was found to have intractable hypoglycemia associated with colon carcinoma metastatic to the liver. Analysis of glucose requirements before death revealed a level of glucose turnover in excess of 12.9 mg/kg X min, consistent with maximally stimulated whole body glucose utilization. This high level of glucose turnover was present at a time when plasma immunoreactive insulin was very low. Insulin binding was measured in freshly isolated circulating mononuclear cells before death and in plasma membranes prepared from several tissues obtained at autopsy. A 3- to 5-fold increase in insulin receptor number was found in the mononuclear cells and liver and muscle plasma membranes. In contrast, skin fibroblasts maintained in tissue culture demonstrated no increase in insulin binding, thus suggesting that the increase in insulin receptors in freshly isolated tissues was acquired rather than intrinsic. Antibodies directed against the insulin receptor were not present. The patient's serum concentration of insulin-like growth factor I was low, but the serum level of nonsuppressible insulin-like protein was elevated. Serum bioassayable insulin-like activity was decreased. Based on tumor bulk at autopsy and in vitro analysis of glucose transport by his tumor cells maintained in monolayer tissue culture, it was estimated that his tumor could directly account for less than one third of the whole body glucose requirement. These data suggest that the increased tissue utilization of glucose in this hypoglycemic patient was caused by proliferation of insulin receptors in liver and muscle induced by his nonislet cell tumor through an unknown humoral mechanism(s).