Parathyroid Hormone-related Protein Levels Research Articles

Thyroid Follicular Adenoma Producing Parathyroid Hormone-related Protein with a Normal Serum Calcium Level

A 64-year-old woman had normal serum calcium and plasma parathyroid hormone levels, despite an extremely high plasma parathyroid hormone-related protein (PTHrP) level. She underwent medical screening at our hospital and several neck tumors were detected by ultrasonography. After surgical resection of these tumors, her plasma PTHrP level was normalized. Histological examination showed that the resected tumors were thyroid follicular adenomas, while immunohistochemistry revealed positive staining with a monoclonal antibody for PTHrP. This is a rare case of thyroid follicular adenoma producing PTHrP in a patient with a normal serum calcium level despite elevation of plasma PTHrP.

Positive Correlation of PTH-Related Peptide with Glucose in Type 2 Diabetes

Type 2 diabetes is characterized by hyperglycemia resulting from insulin resistance in the setting of inadequate beta-cell compensation. Recent studies indicate that for attaining a well-functioning ß-cell mass, parathyroid hormone-related protein (PTHrP) is a very promising candidate among several insulinotropic peptides. In order to elucidate its role, we determine the levels of PTHrP, insulin and c-peptide in type 2 diabetics and in normal subjects in the fasting state. We enrolled 28 patients (16 men and 12 postmenopausal women) with type 2 diabetes and twenty eight aged-matched healthy individuals as control subjects (15 men and 13 women). PTHrP was statistically significant correlated with glucose in type 2 diabetes and in normal subjects in the fasting state. Additionally, PTHrP serum levels exhibited a significant increase in type 2 diabetes compared to control subjects. Interestingly, PTHrP showed a positive correlation with insulin levels only among healthy individuals presumably due to defective glucose stimulated insulin secretion known to occur in type 2 diabetics. In conclusion, the strong positive relation of PTHrP with glucose in the fasting state in patients with type 2 diabetes mellitus raises several questions for further experimentation concerning its exact role and physiological significance.

Conversion of the Nipple to Hair-Bearing Epithelia by Lowering Bone Morphogenetic Protein Pathway Activity at the Dermal-Epidermal Interface

Epithelial appendages, such as mammary glands and hair, arise as a result of epithelial-mesenchymal interactions. Bone morphogenetic proteins (BMPs) are important for hair follicle morphogenesis and cycling and are known to regulate a wide variety of developmental processes. For example, overexpression of BMPs inhibits hair follicle formation. We hypothesized that the down-regulation of the BMP signaling pathway in the basal epidermis expands regions that are competent to form hair follicles and could alter the fate of the epithelium in the mouse nipple to a hair-covered epidermal phenotype. To test our hypothesis, we used a transgenic mouse model in which keratin 14 (KRT14) promoter-mediated overexpression of Noggin, a BMP antagonist, modulates BMP activity. We observed the conversion of nipple epithelium into pilosebaceous units. During normal mammary gland organogenesis, BMPs are likely used by the nipple epithelium to suppress keratinocyte differentiation, thus preventing the formation of pilosebaceous units. In this report, we characterize the morphology and processes that influence the development of hairs within the nipple of the KRT14-Noggin mouse. We demonstrate that Noggin acts, in part, by reducing the BMP signal in the epithelium. Reduction of the BMP signal in turn leads to a reduction in the levels of parathyroid hormone-related protein. We propose that during evolution of the nipple, the BMP pathway was co-opted to suppress hair follicle formation and create a more functional milk delivery apparatus.

Expression of parathyroid hormone-related protein in the partially obstructed and reversed rabbit bladder

Parathyroid hormone-related protein (PTHrP), the main factor responsible for malignant hypercalcemia, is produced by a wide range of normal and malignant tissues. Prior studies in the rabbit model demonstrated that partial bladder outlet obstruction results in calcium-dysregulation characterized by a marked increase in free calcium within the smooth muscle compartment and the stimulation of calcium-activated enzymes, such as calpain and phospholipase A(2). Twenty-four male New Zealand white rabbits were divided into four groups of six each. Following 4 weeks of obstruction, one group of animals was killed, while outlet obstruction was reversed in two additional groups of animals, which were killed 4 and 8 weeks after relieving the obstruction. A group with six sham-operated rabbits served as controls. The expression and localization of PTHrP were detected in muscle and mucosa by immunohistochemistry, using a PTHrP-specific antibody. In the sham-operated group, rabbit bladders showed a low expression of PTHrP in both the mucosa and muscle layers. PTHrP in the 4-week obstructed bladder group, in muscle and mucosa, were 266% and 134% higher than the sham group, respectively. Strong PTHrP immunostaining persisted in the 4-week reversal groups, but it returned to the sham level after 8 weeks of reversal in the muscle layer. As mentioned about the mucosa layer, the PTHrP level returned to control levels more rapidly after 4 weeks of reversal and continued after 8 weeks of reversal. This study showed that PTHrP is increased after partial bladder outlet obstruction and decreased after relieving the obstruction.

Runx2 Transcriptional Activation of Indian Hedgehog and a Downstream Bone Metastatic Pathway in Breast Cancer Cells

Runx2, required for bone formation, is ectopically expressed in breast cancer cells. To address the mechanism by which Runx2 contributes to the osteolytic disease induced by MDA-MB-231 cells, we investigated the effect of Runx2 on key components of the "vicious cycle" of transforming growth factor beta (TGFbeta)-mediated tumor growth and osteolysis. We find that Runx2 directly up-regulates Indian Hedgehog (IHH) and colocalizes with Gli2, a Hedgehog signaling molecule. These events further activate parathyroid hormone-related protein (PTHrP). Furthermore, Runx2 directly regulates the TGFbeta-induced PTHrP levels. A subnuclear targeting deficient mutant Runx2, which disrupts TGFbeta-induced Runx2-Smad interactions, failed to induce IHH and downstream events. In addition, Runx2 knockdown in MDA-MB-231 inhibited IHH and PTHrP expression in the presence of TGFbeta. In vivo blockade of the Runx2-IHH pathway in MDA-MB-231 cells by Runx2 short hairpin RNA inhibition prevented the osteolytic disease. Thus, our studies define a novel role of Runx2 in up-regulating the vicious cycle of metastatic bone disease, in addition to Runx2 regulation of genes related to progression of tumor metastasis.

Hypopharyngeal squamous cell carcinoma producing both granulocyte colony‐stimulating factor and parathyroid hormone‐related protein

A 57-year-old woman was admitted to Hokkaido University Hospital because of dysphagia. Laryngoscopy indicated hypopharyngeal tumor histologically diagnosed as squamous cell carcinoma (SCC). A combination of radiotherapy and chemotherapy was performed for 2 months, and the hypopharyngeal lesion completely regressed. After 4 months, fever, anorexia, and malaise appeared, and chest X-ray and CT indicated two large tumors in the right lung. Transbroncheal lung biopsy (TBLB) specimens were diagnosed as SCC. Laboratory data showed high levels of serum granulocyte colony-stimulating factor (G-CSF) and parathyroid hormone-related protein (PTHrP). Subsequently, positron emission tomography (PET) showed multiple metastases to several organs including the liver, spine, skull, and thigh. Two months after readmission, the patient died with no success of chemotherapy. At autopsy, the lung tumor was clearly positive for both G-CSF and PTHrP on immunohistostaining. Retrospectively, examination showed that the primary pharyngeal tumor was focally positive for these two cytokines. Thus, a certain population of hypopharyngeal cancer producing G-CSF and PTHrP, spread to various organs and contributed to the rapid progression and poor prognosis. This case is presented with a discussion of several other cases in the literature.

Adenosquamous carcinoma of the pancreas associated with humoral hypercalcemia of malignancy (HHM)

We report a rare case of adenosquamous carcinoma of the pancreas associated with humoral hypercalcemia of malignancy (HHM) in which parathyroid hormone-related protein (PTH-rP) was identified as the causative factor of hypercalcemia. A 72-year-old Japanese man was admitted to our institution complaining of fever and abdominal pain. Abdominal computed tomography demonstrated a large tumor in the body of the pancreas, with multiple liver metastases. Both serum calcium and PTH-rP levels were elevated. No accumulation was observed on bone scan with technetium-99. The patient died of pneumonia 3 months after admission. Autopsy demonstrated that the neoplasm in the pancreas showed an abrupt histological transition from adenocarcinoma to squamous cell carcinoma. PTH-rP was identified in the primary pancreatic tumor cells by immunohistochemical examination and a reverse-transcription polymerase chain reaction (RTPCR) method. We concluded that PTH-rP was the causative factor of the HHM, based on the laboratory data, immunohistochemical examination, and messenger RNA (mRNA) expression. This is a very rare report of adenosquamous cell carcinoma of the pancreas associated with HHM.

Switching of G-protein Usage by the Calcium-sensing Receptor Reverses Its Effect on Parathyroid Hormone-related Protein Secretion in Normal Versus Malignant Breast Cells

The calcium-sensing receptor (CaR) is a G-protein-coupled receptor that signals in response to extracellular calcium and regulates parathyroid hormone secretion. The CaR is also expressed on normal mammary epithelial cells (MMECs), where it has been shown to inhibit secretion of parathyroid hormone-related protein (PTHrP) and participate in the regulation of calcium and bone metabolism during lactation. In contrast to normal breast cells, the CaR has been reported to stimulate PTHrP production by breast cancer cells. In this study, we confirmed that the CaR inhibits PTHrP production by MMECs but stimulates PTHrP production by Comma-D cells (immortalized murine mammary cells) and MCF-7 human breast cancer cells. We found that changes in intracellular cAMP, but not phospholipase C or MAPK signaling, correlated with the opposing effects of the CaR on PTHrP production. Pharmacologic stimulation of cAMP accumulation increased PTHrP production by normal and transformed breast cells. Inhibition of protein kinase A activity mimicked the effects of CaR activation on inhibiting PTHrP secretion by MMECs and blocked the effects of the CaR on stimulating PTHrP production in Comma-D and MCF-7 cells. We found that the CaR coupled to Galphai in MMECs but coupled to Galphas in Comma-D and MCF-7 cells. Thus, the opposing effects of the CaR on PTHrP production are because of alternate G-protein coupling of the receptor in normal versus transformed breast cells. Because PTHrP contributes to hypercalcemia and bone metastases, switching of G-protein usage by the CaR may contribute to the pathogenesis of breast cancer.

Expression of Parathyroid-Hormone- Related Protein in the Partially Obstructed Rabbit Bladder

Introduction: Parathyroid-hormone-related protein (PTHrP) is considered as an autocrine/paracrine regulator of growth and/or differentiation in normal and malignant tissues. We determined the distribution and density of the expression of PTHrP in the rabbit bladder during growth in response to partial outlet obstruction and its relation with the smooth muscle/collagen ratio. Materials and Methods: A total of 30 male New Zealand White rabbits were studied. After 7, 14, 28 or 56 days of obstruction, 6 rabbits per group were sacrificed and the bladder extracted. Six sham-operated rabbits served as controls. The expression and localization of PTHrP or collagen type III were detected by immunohistochemistry using specific antibodies. Results: The levels of PTHrP were progressively increased by 14 days of obstruction, whereas they decreased after 14 days, although the PTHrP positivity was higher than in sham controls by 28 and 56 days of obstruction. PTHrP staining was related to the smooth muscle/collagen ratio, both showing a peak in rabbits obstructed for 14 days. Conclusions: These data indicate that PTHrP may play an important regulatory role in the cellular and vascular response to partial outlet obstruction.

Variable number of tandem repeats polymorphism in parathyroid hormone-related protein as predictor of peak bone mass in young healthy Finnish males

Mice with osteoblast-specific deletion of parathyroid hormone-related protein (PTHrP) exhibit impaired recruitment and increased apoptosis of osteogenic cells resulting in decreased bone formation and premature osteoporosis. The PTHrP levels within the bone microenvironment are therefore critical in influencing bone mass acquisition. Whether this is applicable in humans has not been established. Here, we studied the association of a variable number of tandem repeats (VNTR) polymorphism in PTHrP with peak bone mass. Enrolled in the study were 234 young Finnish males, with median age of 19.6 years (range 18.3-20.6 years). Lifestyle factors, serum bone markers, osteodensitometric measurements (lumbar spine and hip) and calcaneal quantitative ultrasound readings were obtained. The PTHrP VNTR length was determined by the PCR amplification of genomic DNA extracted from peripheral blood and correlated to bone parameters by the multiple regression models. The presence of at least one 252 bp allele was associated with increased lumbar spine bone mineral density (BMD; P<0.0034), broadband ultrasound attenuation (BUA; P<0.0012) and speed-of-sound (SOS; P<0.0023) measurements. The correlation with increased lumbar spine BMD (P=0.0008), BUA (P=0.005) and SOS (P=0.001) was further strengthened by the pairing of the 252 bp allele with a 460 bp allele in comparison with those without any 252 bp allele. Electrophoretic mobility shift assays were used to illustrate the potential transcriptional functionality of the VNTR sequence. The results indicate that the PTHrP VNTR sequence likely modulates local PTHrP expression within the skeletal microenvironment and could serve as a diagnostic predictor of peak bone mass acquisition.

Hypercalcemia during Pregnancy, Puerperium, and Lactation: Review and a Case Report of Hypercalcemic Crisis after Delivery Due to Excessive Production of PTH-related Protein (PTHrP) without Malignancy (Humoral Hypercalcemia of Pregnancy)

Hypercalcemia during pregnancy or after delivery is uncommon, and mostly associated with primary hyperparathyroidism (PHPT). If unrecognized, it may increase maternal and fetal morbidity. In a very few patients with PHPT, hypercalcemic crisis develops during pregnancy and particularly after delivery, since calcium transport from the mother to the fetus is abruptly disrupted. Hypercalcemia may also develop in pregnant women due to PTH-related protein (PTHrP)-producing malignant tumors (humoral hypercalcemia of malignancy). Since PTHrP is produced physiologically in fetal and maternal tissues, hypercalcemia may occasionally develop during pregnancy, puerperium, and lactation due to excessive production of PTHrP in the placenta and/or mammary glands. PTHrP may also be involved in milk-alkali syndrome that develops during pregnancy. Although non-malignant hypercalcemia is usually mild, we report a 28-years-old pregnant woman who developed hypercalcemic crisis after normal delivery of an infant. On the first postpartum day, the corrected serum calcium concentration increased to 19.4 mg/dl with a markedly increased serum level of PTHrP (28.4 pmol/L) (normal <1.1 pmol/L). After administration of saline and pamidronate, the serum levels of calcium and PTHrP rapidly normalized. Extensive examination revealed no malignant lesion, suggesting that the placenta may have been producing an excessive amount of PTHrP (humoral hypercalcemia of pregnancy). We review case reports of non-malignant hypercalcemic crisis associated with pregnancy indexed in PubMed in which serum levels of intact PTH and/or PTHrP were described, and stress that rapid control of hypercalcemia is mandatory to save the life of the mother and the infant.

PTHrP contributes to the anti-proliferative and integrin α6β4-regulating effects of 1,25-dihydroxyvitamin D 3

Parathyroid hormone-related protein (PTHrP) increases the growth and metastatic potential of prostate cancer cells, making it important to control PTHrP expression in these cells. 1,25-Dihydroxyvitamin D 3 [1,25(OH) 2D 3] suppresses PTHrP expression and exerts an anti-proliferative effect in prostate carcinoma cells. We used the human prostate cancer cell line C4-2 as a model system to ask whether down-regulation of PTHrP expression by 1,25(OH) 2D 3 plays a role in the anti-proliferative effects of 1,25(OH) 2D 3. Since PTHrP increases the expression of the pro-invasive integrin α6β4, we also asked whether 1,25(OH) 2D 3 decreases integrin α6β4 expression in C4-2 cells, and whether modulation of PTHrP expression by 1,25(OH) 2D 3 plays a role in the effects of 1,25(OH) 2D 3 on integrin α6β4 expression. Two strategies were utilized to modulate PTHrP levels: overexpression of PTHrP (−36 to +139) and suppression of endogenous PTHrP expression using siRNAs. We report a direct correlation between PTHrP expression, C4-2 cell proliferation and integrin α6β4 expression at the mRNA and cell surface protein level. Treatment of parental C4-2 cells with 1,25(OH) 2D 3 decreased cell proliferation and integrin α6 and β4 expression. These 1,25(OH) 2D 3 effects were significantly attenuated in cells with suppressed PTHrP expression. 1,25(OH) 2D 3 regulates PTHrP expression via a negative vitamin D response element (nVDRE) within the noncoding region of the PTHrP gene. The effects of 1,25(OH) 2D 3 on cell proliferation and integrin α6β4 expression were significantly attenuated in cells overexpressing PTHrP (−36 to +139), which lacks the nVDRE. These findings suggest that one of the pathways via which 1,25(OH) 2D 3 exerts its anti-proliferative effects is through down-regulation of PTHrP expression.

N‐terminal parathyroid hormone‐related protein levels in human intrauterine growth restricted pregnancies

N-terminal parathyroid hormone-related protein has a vital role in regulating cell growth and differentiation, uteroplacental vasodilatation, uterine muscle relaxation, and placental transport. These functions are compromised in intrauterine growth restriction. We aimed to investigate N-terminal parathyroid hormone-related protein concentrations in maternal, fetal, and neonatal plasma of intrauterine-growth-restricted and appropriate for gestational age pregnancies. Plasma N-terminal parathyroid hormone-related protein levels were determined in 40 mothers and their 20 intrauterine-growth-restricted and 20 appropriate for gestational age singleton full-term fetuses and neonates on postnatal days 1 and 4. Fetal N-terminal parathyroid hormone-related protein levels were significantly lower in the intrauterine growth restriction group (b=1.166, 95%CI: 0.430-1.902, p=0.003) and correlated with the customized centiles of the infants (r=0.407, p=0.009). In the appropriate for gestational age group, neonatal day 1 N-terminal parathyroid hormone-related protein levels were significantly lower compared to maternal (p<0.001) and fetal (p=0.022) ones. Fetal and neonatal day 1 levels were significantly lower in males (b=-1.303, 95%CI: -2.508 to -0.097, p=0.036, and b=-0.802, 95%CI: -1.5 to -0.105, p=0.027, respectively). In the intrauterine growth restriction group, maternal N-terminal parathyroid hormone-related protein levels were significantly increased compared to fetal (p<0.001) and neonatal day 1 (p=0.001) levels. The reduced fetal N-terminal parathyroid hormone-related protein concentrations in intrauterine growth restriction may reflect compromised placental function and impaired fetal growth, suggesting that N-terminal parathyroid hormone-related protein may be involved in the pathogenesis of intrauterine growth restriction.

Involvement of cyclooxygenase‐2 in the tumor site‐dependent production of parathyroid hormone‐related protein in colon 26 carcinoma

It has been shown that in the mouse colon 26 tumor model, tumors grown in the subcutis (subcutis colon 26) caused early onset of cachectic syndromes, whereas those in the liver (liver colon 26) did not. Both interleukin (IL)-6 and parathyroid hormone-related protein (PTHrP) were involved in the development of cachectic syndromes in this tumor model. However, whether expression of PTHrP and IL-6 is differently regulated in the tumor microenvironment is unclear. In the present study, culturing the colon 26 cells under different conditions in vitro revealed that IL-6 production was increased by monolayer culture under a low-glucose condition but not by spheroid culture. In contrast, PTHrP production was increased by spheroid culture but not by monolayer culture, even under a low-glucose condition. Gene expression profiling revealed that the expression of cyclooxygenase (COX)-2 was up-regulated in both subcutis colon 26 and spheroid cultures, and that COX-2 inhibitor NS-398 suppressed PTHrP production in spheroid cultures. Furthermore, administration of NS-398 decreased the PTHrP level without affecting the tumor growth in mice bearing subcutis colon 26. These results demonstrate that production of PTHrP and IL-6 largely depends on the microenvironments in which tumors are developed or metastasized and that up-regulation of COX-2 in a necrobiotic environment leads to PTHrP production, thereby causing cachectic syndromes.

Differential Diagnosis of Hypercalcemia in Renal Malignancy

We report a case of large cell B-cell lymphoma of the kidney associated with humoral hypercalcemia of malignancy. A 70-year-old man presented with renal failure and hypercalcemia. After the workup, the patient was thought to have renal cell carcinoma and underwent radical nephrectomy. The pathologic evaluation showed a large cell lymphoma with a B-cell phenotype. Reevaluation of the patient's serum revealed a high calcitriol level with low parathyroid hormone and parathyroid hormone-related protein levels, consistent with the final pathologic findings. The differential diagnosis of hypercalcemia in renal malignancy is presented.

Transcriptional regulation of parathyroid hormone-related protein promoter P2 by NF-κB in adult T-cell leukemia/lymphoma

Parathyroid hormone-related protein (PTHrP) plays a primary role in the development of humoral hypercalcemia of malignancy (HHM) that occurs in the majority of patients with adult T-cell leukemia/lymphoma (ATLL) due to human T-cell lymphotropic virus type-1 (HTLV-1) infection. We previously showed that ATLL cells constitutively express high levels of PTHrP via activation of promoters P2 and P3, resulting in HHM. In this study, we characterized a nuclear factor-kappaB (NF-kappaB) binding site in the P2 promoter of human PTHrP. Using electrophoretic mobility shift assays, we detected a specific complex in Tax-expressing human T cells composed of p50/c-Rel, and two distinct complexes in ATLL cells consisting of p50/p50 homodimers and a second unidentified protein(s). Chromatin immunoprecipitation assays confirmed in vivo binding of p50 and c-Rel on the PTHrP P2 promoter. Using transient co-transfection with NF-kappaB expression plasmids and PTHrP P2 luciferase reporter-plasmid, we showed that NF-kappaB p50/p50 alone and p50/c-Rel or p50/Bcl-3 cooperatively upregulated the PTHrP P2 promoter. Furthermore, inhibition of NF-kappaB activity by Bay 11-7082 reduced PTHrP P2 promoter-initiated transcripts in HTLV-1-infected T cells. In summary, the data demonstrated that transcriptional regulation of PTHrP in ATLL cells can be controlled by NF-kappaB activation and also suggest a Tax-independent mechanism of activation of PTHrP in ATLL.

Parathyroid hormone-related protein and calcium regulation in vitamin D-deficient sea bream (Sparus auratus)

Gilthead sea bream (Sparus auratus L.) were fed a vitamin D-deficient diet for 22 weeks. Growth rate, whole body mineral pools and calcium balance were determined. Plasma parathyroid hormone-related protein (PTHrP) and calcitriol levels were assessed. Expression of mRNA for pthrp and pth1r was quantified in gills and hypophysis. Fish on vitamin D-deficient diet (D- fish) showed reduced growth and lower calcium turnover (calcium influx, efflux and accumulation rates decreased) and unaltered plasma calcium levels. Plasma calcitriol levels became undetectable, PTHrP levels decreased in the D- fish. In controls, a significant increase in plasma PTHrP level over time was seen, i.e. it increased with body mass. Relationships were found between plasma PTHrP and the whole body pools of calcium, phosphorus and magnesium, indicative of a role for PTHrP in bone development. Expression of pthrp and pth1r mRNA was down-regulated in the hypophysis of D-fish, whereas in gill tissue, pthrp and pth1r mRNA were up-regulated. We conclude that lower pthrp mRNA expression and plasma values in D- fish reflect lower turnover of PTHrP under conditions of hampered growth; up-regulation of pthrp mRNA in gills indicate compensatory paracrine activity of PTHrP during calcitriol deficiency to guarantee well-regulated branchial calcium uptake. This is the first report to document a relation between PTHrP and calcitriol in fish.

A PTH/PTHrP receptor antagonist blocks the hypercalcemic response to estradiol-17β

Estradiol (E(2)) increases circulating calcium and phosphate levels in fish, thus acting as a hypercalcemic and hyperphosphatemic factor during periods of high calcium requirements, such as during vitellogenesis. Since parathyroid hormone (PTH)-related protein (PTHrP) has been shown to be calciotropic in fish, we hypothesized that the two hormones could be mediating the same process. Sea bream (Sparus auratus) juveniles receiving a single intraperitoneal injection of piscine PTHrP(1-34) showed an elevation in calcium plasma levels within 24 h. In contrast, injections of the PTH/PTHrP receptor antagonist PTHrP(7-34) decreased circulating levels of calcium in the same period. Intraperitoneal implants of estradiol-17beta (E(2); 10 microg/g) evoked significant increases of circulating plasma levels of calcium and phosphorus and a sustained increases of circulating plasma levels of PTHrP. However, a combined treatment of E(2) and PTHrP(7-34) evoked a markedly lower calcium response compared with E(2) alone. We conclude that PTHrP or a related peptide that binds the PTH/PTHrP receptor mediates, at least in part, the hypercalcemic effect of E(2) in calcium and phosphate balance in fish.

Stable Overexpression of Smad7 in Human Melanoma Cells Impairs Bone Metastasis

Melanoma has a propensity to metastasize to bone, where it is exposed to high concentrations of transforming growth factor-beta (TGF-beta). Because TGF-beta promotes bone metastases from other solid tumors, such as breast cancer, we tested the role of TGF-beta in melanoma metastases to bone. 1205Lu melanoma cells, stably transfected to overexpress the natural TGF-beta/Smad signaling inhibitor Smad7, were studied in an experimental model of bone metastasis whereby tumor cells are inoculated into the left cardiac ventricle of nude mice. All mice bearing parental and mock-transfected 1205Lu cells developed osteolytic bone metastases 5 weeks post-tumor inoculation. Mice bearing 1205Lu-Smad7 tumors had significantly less osteolysis on radiographs and longer survival compared with parental and mock-transfected 1205Lu mice. To determine if the reduced bone metastases observed in mice bearing 1205Lu-Smad7 clones was due to reduced expression of TGF-beta target genes known to enhance metastases to bone from breast cancer cells, we analyzed gene expression of osteolytic factors, parathyroid hormone-related protein (PTHrP) and interleukin-11 (IL-11), the chemotactic receptor CXCR4, and osteopontin in 1205Lu cells. Quantitative reverse transcription-PCR analysis indicated that PTHrP, IL-11, CXCR4, and osteopontin mRNA steady-state levels were robustly increased in response to TGF-beta and that Smad7 and the TbetaRI small-molecule inhibitor, SB431542, prevented such induction. In addition, 1205Lu-Smad7 bone metastases expressed significantly lower levels of IL-11, connective tissue growth factor, and PTHrP. These data suggest that TGF-beta promotes osteolytic bone metastases due to melanoma by stimulating the expression of prometastatic factors via the Smad pathway. Blockade of TGF-beta signaling may be an effective treatment for melanoma metastasis to bone.

Calcium-regulating peptide hormones and blood electrolytic balance in chronic heart failure

Calcium-regulating system is important for the functional activity of myocardium. However, little is known about the role of this system in the pathogenesis of cardiovascular diseases. Blood samples from the patients with chronic heart failure (CHF) caused by ischaemic disease (coronary artery disease) (NYHA class I–IV) were used to analyze the levels of calcium, inorganic phosphate, sodium, potassium, parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP). The heart beat rate and arterial blood pressure were chosen as additional tests for the functional status of cardiovascular system. The alteration of electrolytes homeostasis was found dependent on the severity of the pathology being maximally expressed in the NYHA class IV patients. Similar tendency was demonstrated for circulating PTH and PTHrP with the highest blood concentrations observed in patients of the NYHA class III and IV. The extent of these changes was found more pronounced in the female patients. It is suggested that the calcium-regulating hormonal system is involved in the pathogenesis of the ischaemic heart disease; however the sharp increase of PTH and PTHrP at the severe stages of pathology may play a compensatory role in maintaining the heart function.