Antibodies to parathyroid hormone-related protein lower serum calcium in athymic mouse models of malignancy-associated hypercalcemia due to human tumors.

A parathyroid hormone-related protein (PTHrP) has recently been isolated from tumors associated with hypercalcemia. In the present study, we tested the effects of neutralizing antisera to the PTHrP on serum calcium and urine cAMP in two animal models of malignancy-associated hypercalcemia. The animal models consisted of (a) a human squamous cell lung cancer and (b) a human laryngeal cancer, both serially carried in athymic mice. The antisera specifically reduced the elevated serum calcium and urinary cAMP levels in the tumor-bearing animals. We conclude that PTHrP plays a major role in the pathogenesis of malignancy-associated hypercalcemia.

Treatment of cancer-associated hypercalcemia with cisplatin.

Cisplatin (cis-platinum) has been shown to lower cancer-associated humoral hypercalcemia in an animal model and to inhibit bone resorption in vitro. This prospective study was designed to evaluate the efficacy of cisplatin in treating cancer-associated hypercalcemia in humans. Thirteen patients with severe hypercalcemia refractory to rehydration were treated with a 24-hour infusion of cisplatin, 100 mg/m2. Serial measurements of serum calcium and tumor size were made following cisplatin treatment and compared with pretreatment values. Nine patients (69%) achieved normocalcemia after treatment with cisplatin; and mean duration of benefit was 38 days in these patients. No reduction in tumor size was seen. All patients died of progressive cancer. We conclude that cisplatin can control malignant hypercalcemia for relatively long periods, and that its mechanism of action is not due to a reduction in tumor size.

Effect of epidermal growth factor infusion on serum and urine calcium in mice.

Transforming growth factors (TGFs) have been implicated in the pathogenesis of the hypercalcemia in malignancy (HM). In order to evaluate the role of these growth factors (epidermal growth factor (EGF) and TGF-alpha acting via the EGF receptor) in the development of HM, we studied the effect of 2 doses of EGF (0.1 and 0.3 microgram/g/day) given for 7 days as a continuous infusion on serum and urine calcium in athymic mice. These infusions had no effect on serum and urine Ca values in this study. In order to assess the biological activity of the infused EGF, other known effects on gastric and pancreatic weights were evaluated. EGF-infused animals had significantly greater gastric and pancreatic weights than controls. Thus, EGF infusion into mice in doses which elicited known biological effects failed to have an effect on serum and urine Ca. An infusion of bovine parathyroid hormone 1-34 at the dose of 0.1 microgram/g/day resulted in significant hypercalcemia.

Increased renal calcium reabsorption in an animal model of hypercalcemia of human malignancy.

The present studies examined renal calcium (Ca) clearance in an animal model of malignancy-associated humoral hypercalcemia (MAHH) (a human squamous cell lung carcinoma carried in athymic mice). Three groups of animals--controls, normocalcemic tumor-bearing animals and hypercalcemic tumor-bearing animals--were studied in the basal state and during Ca infusion. Baseline Ca clearance was slightly but significantly elevated in the tumor-bearing hypercalcemic animals compared with the other two groups of animals. This clearance value was, however, inappropriately low for the serum Ca value. In the control and in the normocalcemic tumor-bearing animals, Ca clearance increased markedly during Ca infusion. This increase in renal Ca clearance was markedly blunted in the hypercalcemic animals compared with both the controls and the normocalcemic tumor-bearing animals. We conclude that increased renal Ca resorption contributes significantly to the pathogenesis of hypercalcemia of malignancy.

Quantitative bone histomorphometry in nude mice bearing a human squamous cell lung cancer.

We performed quantitative bone histomorphometry on lumbar vertebrae in hypercalcemic tumor-bearing athymic mice carrying a human squamous cell carcinoma. For comparison, studies were also performed in athymic mice that received bovine 1-34 parathyroid hormone (PTH) infusion at the rate of 0.167 micrograms/hr for 7 days. In both the PTH-infused and tumor-bearing animals, percent cortical and total bone areas were significantly reduced as compared to controls, whereas trabecular bone was significantly reduced only in the tumor-bearing animals. Trabecular perimeter lined by osteoclasts was significantly increased in both tumor-bearing (1.7-fold) and PTH-infused animals (2.8-fold) compared to control mice. Trabecular perimeter lined by active osteoblasts was significantly reduced in the tumor-bearing animals (to 42% of control) and unchanged in the PTH-infused animals (97% of control). Tumor-bearing animals had significantly reduced resorptive as well as formative surfaces as compared to the PTH-infused animals. Dynamic histomorphometry revealed a marked reduction in bone formation rate (23% of control) in the tumor-bearing animals. The studies therefore demonstrate a marked inhibition of bone formation associated with increased bone resorption in this model of hypercalcemia of malignancy. These observations are similar to those seen in the human syndrome.

Effects of cisplatin on parathyroid hormone- and human lung tumor-induced bone resorption.

We have previously shown that dichlorodiamine platinum (DDP), or cisplatin, a cancer chemotherapeutic agent, is effective in the treatment of malignancy-associated hypercalcemia. In the present studies, we evaluated its effects on bovine parathyroid hormone (PTH)- or tumor-induced bone resorption in vitro in the neonatal mouse calvarial bone resorption assay. PTH alone or tumor extract (TE) of a human squamous cell lung cancer alone caused a significant increase in the bone resorption and in the number of osteoclasts in the calvaria. The addition of 3 and 10 micrograms/ml DDP inhibited the PTH- or TE-induced bone resorption. Lower doses of 1 and 2 micrograms/ml DDP, although not effective in inhibiting the PTH-induced bone resorption, were effective in lowering the TE-induced bone resorption. The number of osteoclasts was also reduced by DDP treatment. We therefore conclude that DDP is effective in the treatment of malignancy-associated hypercalcemia by virtue of its inhibitory effects on osteoclast numbers and on bone resorption.

Tumor resection and antibodies to parathyroid hormone-related protein cause similar changes on bone histomorphometry in hypercalcemia of cancer.

Bone resorption is increased in both humoral hypercalcemia of malignancy (HHM) and primary hyperparathyroidism. On the other hand, bone formation parameters are increased in primary hyperparathyroidism and decreased in HHM. Recently, a PTH-related protein (PTHrP) has been shown to be responsible for the hypercalcemia in the syndrome of HHM. In the present study we evaluated the effects of a neutralizing antiserum to PTHrP on bone histomorphometric parameters in hypercalcemic athymic mice bearing a human squamous cell lung cancer. These effects were compared to those of tumor resection. Similar to the effects of tumor resection, the antiserum to PTHrP resulted in a decrease in serum Ca levels, a decrease in bone resorption, and an increase in bone formation parameters. The studies, therefore, indicate that PTHrP is the major factor responsible for all of the features, including the decreased bone formation seen in HHM.

Development of skeletal metastasis by human prostate cancer in athymic nude mice.

The biology of skeletal metastasis is poorly understood. In order to establish an animal model of bone metastasis, cells from a human prostate cancer cell line (PC-3) were injected into the tail veins of athymic nude mice while the inferior vena cava was occluded. This technique was used in order to divert cells into the vertebral venous plexus. A control group of animals received tumor cells without caval occlusion. Bone lesions developed in 3/16 (19 per cent) experimental mice and in none of the control mice. The incidence of lung metastasis was significantly decreased in the experimental mice (5/16) as compared with non-occluded control mice (14/16). Two tumor sublines were established from explant cultures of bone lesions. Injection of these cells resulted in bone metastasis in 19/36 (53 per cent) mice (P = 0.03 compared with the parent line). The incidence of lung lesions was also increased. The predominant site of bone metastasis was the lumbar vertebrae; other affected sites were the pelvis and femurs. All bone lesions resulted in extensive bone destruction. The successful development of bone metastasis using the technique of caval occlusion lends support to the hypothesis that entry of cells into the vertebral circulation is an important step in the development of these lesions. This model should be of value in understanding the pathogenesis of bone metastasis, and in studying the effects of various agents on the prevention and control of these lesions.

A case of therapy-related extramedullary acute promyelocytic leukemia.

We report a patient with extramedullary acute promyelocytic leukemia (APL) occurring after radiation therapy for carcinoma of the prostate. To the authors' knowledge, this patient represents the first case of cytogenetically and fluorescence in situ hybridization (FISH) confirmed therapy-related extramedullary APL. In contrast to the majority of previously reported t-APL, this case underwent a very unfavorable course.

Assessment of coagulation system activation using spot urine measurements.

Coagulation system activation is most commonly assessed by measuring levels of one or more proteins in peripheral blood. Because faulty blood-drawing can cause activation of the coagulation system, artifactual elevations of such markers have been reported. We have therefore investigated the possibility of using randomly collected ('spot') urine samples as a non-invasive means of assessing the state of coagulation system activation. Using a commercially available enzyme-linked immunosorbent assay kit designed to measure plasma levels of fragment 1 + 2, we found immunoreactive fragment 2 in healthy control subjects, and significantly increased levels in diabetic and non-diabetic pregnant subjects, and patients with venous thromboembolism, prostate cancer, and diabetes. Measurements of excretion of immunoreactive fragment 2 are worth further study as an adjunct or alternative to plasma-based assays designed to detect or quantify coagulation system activation.

Phase II trial of cisplatin, etoposide, and 5-fluorouracil in advanced non-small-cell lung cancer: an Eastern Cooperative Oncology Group Study (PB586).

Advanced non-small-cell lung cancer (NSCLC) remains an incurable disease despite significant progress in chemotherapy. We conducted a phase II clinical trial to investigate the efficacy and toxicity of a cisplatin, etoposide, and 5-fluorouracil (5-FU) combination in advanced metastatic and/or recurrent NSCLC. Forty patients with advanced, recurrent, or metastatic, measurable NSCLC were treated with cisplatin, 60 mg/m2 intravenously (i.v.) on day 1; etoposide, 120 mg/m2/day i.v. on days 1, 2, and 3; and 5-FU. 1,000 mg/m2/day i.v. continuous infusion on days 1 through 5. Treatment was administered in 4-week cycles. Thirty patients had distant metastases and were previously untreated, and 10 patients had recurrent disease after prior treatment with either surgery (1 patient), radiation therapy (5 patients), or both treatments (4 patients). Twenty-nine patients were evaluable for response. Seven (24%) patients achieved a partial remission (PR), 18 (62%) had stable disease (SD), and 8 (14%) had progressive disease (PD). Overall median survival was 7.9 months (range, 0.4-27.4 months). Patients who achieved a PR had a median survival of 23.5 months (9.3-27.4 months). In contrast, patients with SD had a median survival of 9.9 months (2.5-25.3 months), and patients with PD had a median survival of 2.1 months (1-9.3 months). Median duration of response of 27.1 weeks (4.9-76.5 weeks) for patients with PR, and time to progression was 13.4 weeks (3.7-54.5 weeks) for patients with SD. Toxicity was primarily hematologic and gastrointestinal, and there were three deaths due to infection. The combination of cisplatin, 5-FU, and etoposide as administered in this study appears to have considerable toxicity and does not appear to be superior to other cisplatin-containing regimens used for the treatment of advanced NSCLC.

In vivo and in vitro approaches to study metastasis in human prostatic cancer.

Prostate cancer is the most common malignancy in American males and is second only to lung cancer as a cause of death in the United States. Clinically, radical prostatectomy offers a patient with locally contained disease an excellent chance for cure. For patients with metastatic disease, the current therapies are merely palliative. Understanding the biology of prostate cancer metastasis should facilitate the development of novel and effective therapeutic modalities. Crucial to this objective is the availability of human tumor systems in which the biology of metastasis can be studied. The present chapter will briefly assess various in vivo and in vitro approaches to study metastasis in human prostate cancer. Utilization of athymic nude mice has played an important role in maintaining human prostatic cancer cells as xenografts and has provided an opportunity to establish site-specific subpopulations of the parental cell lines for further characterization and investigation. At present, a few established cell lines have been useful for this purpose. Fresh tumor specimens, unfortunately, have shown limited ability to grow in nude mice. The recent development of novel approaches to permit the maintenance of freshly harvested prostate cancers has been encouraging. The use of reconstituted basement membrane (Matrigel) for co-injection with cancer cells into the subcutaneous tissues has supported growth of biologically indolent tumors. Another approach is to administer tumor cells orthotopically into the prostate of recipient nude mice. Bone marrow metastases in nude mice have been rare in the past. Recently, three approaches have been shown to be successful in accomplishing bony metastasis with PC-3 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Patterns of metastasis by the human prostate cancer cell line PC-3 in athymic nude mice.

Cells from the PC-3 human prostate cancer cell line were evaluated in athymic nude mice in order to determine the influence of size of the primary tumor and site inoculation on the incidence and pattern of metastasis. At autopsy, all organs, including the skeleton, were evaluated for metastasis. Subcutaneous injections resulted in metastases to the draining axillary lymph node and lungs (56% and 13%, respectively), and were correlated with size of the primary tumor. Tail vein injection resulted in a high incidence of lung metastasis, while injection into the peritoneal space, spleen, and seminal vesicles resulted in intraabdominal tumor growth, liver metastasis, and large tumors within the seminal vesicles, respectively. Skeletal metastases were not observed in any of the animals studied. We conclude that injection of PC-3 cells into various sites results in different patterns of metastasis, but may not constitute an entirely suitable animal model of human prostate cancer due to the lack of metastasis to the skeleton.

Analysis of gene amplification in human tumor cell lines.

Oncogene amplification has been observed in various primary tumors and tumor-derived cell lines. In several types of cancer, amplification of specific oncogenes is correlated with the stage of tumor progression. To estimate the frequency of gene amplification in other tumor types and to determine whether the ability to grow in vivo is associated with gene amplification in tumor cell lines, we have developed a modified version of the in-gel renaturation assay that detects human DNA sequences of unknown nature amplified as little as 7- to 8-fold. This assay was used to screen 16 cell lines derived from various solid tumors and leukemias. Amplified DNA sequences were detected in only one cell line, Calu-3 lung adenocarcinoma. This cell line was found to contain coamplified NGL (formerly termed neu) and ERBA1 oncogenes. However, when one of the amplification-negative cell lines, PC-3 prostatic carcinoma, was selected for in vivo growth in nude mice, amplified DNA sequences became detectable in these cells. The amplified sequences included the MYC oncogene, which showed no amplification in the parental cell line but was amplified 10- to 12-fold in the in vivo-selected cells. MYC amplification may, therefore, provide tumor cells with a selective advantage specific for in vivo growth.

Use of clonidine to treat hot flashes secondary to leuprolide or goserelin.

OBJECTIVE: To determine the effects of clonidine, a centrally acting adrenergic agonist, in abating symptoms of hot flashes in men receiving either leuprolide or goserelin for prostate cancer. DESIGN: Patients were administered transdermal or oral clonidine 0.1-0.2 mg/d. Dosages were increased in increments of 0.1-0.3 mg/d every two to four weeks if symptoms persisted or until adverse effects developed. SETTING: Medical oncology clinic at the University of Illinois and the hypertension clinic at the Veterans Affairs West Side Medical Center. PARTICIPANTS: Consenting male patients were eligible for the study if they were receiving leuprolide or goserelin for prostate cancer and were experiencing hot flashes. Exclusion criteria included diastolic blood pressure of 75 mm Hg or below or a history of adverse reactions to clonidine. MAIN OUTCOME MEASURES: Effectiveness of clonidine was determined by questioning patients about frequency, severity, and duration of hot flashes at baseline and at two- to four-week intervals. RESULTS: All four patients receiving clonidine experienced a partial response within two weeks of starting treatment. No dose-dependent response was observed. Adverse effects were noted in one patient but did not result in discontinuation. CONCLUSIONS: Our results document the first report of the use of clonidine to treat hot flashes secondary to leuprolide or goserelin therapy. Symptomatic improvement was noted in all four patients. Further evaluation of clonidine as well as other centrally acting adrenergic agonists is needed.

Effect of etidronate disodium on the development of bone lesions in an animal model of bone metastasis using the human prostate cancer cell line PC-3.

We have established an animal model of bone metastasis using the PC-3 human prostate tumor cell line. In order to assess whether inhibition of bone resorption would prevent the development of bone metastasis, the diphosphonate etidronate (EHDP) was administered to 20 mice at a dose of 30 mg/kg subcutaneously daily starting 2 days prior to injection of tumor cells. Control mice received daily injections of the saline vehicle. In the EHDP-treated mice, there was no significant reduction in the incidence of bone metastasis, the size of the lesions, or the number of bone lesions per mouse. Approximately 50% of the mice developed bone metastasis, which was similar to the control group and similar to what was observed in earlier studies with this animal model. Histomorphometric analysis of bones showed marked inhibition of mineralization in EHDP-treated mice, thus indicating biological effect on the bone. Therefore, the use of EHDP in biologically effective doses failed to reduce the incidence, size, or number of bone metastases in this animal model.

Effects of hypercalcemia-producing tumor extract and parathyroid hormone on osteoclast ultrastructure.

Hypercalcemia is a frequent complication of cancer. Recently, parathyroid hormone-related protein has been isolated from tumors associated with this syndrome. In the present study, the effects of tumor-derived hypercalcemic factor and bovine parathyroid hormone (PTH) on bone were compared in an organ culture system using calvarial bones from newborn mice. Mouse calvaria were incubated for 72 h with control medium or media containing 0.15 mg/m tumor extract (TE) or 2 x 10(-9) M PTH. Bone resorption, as assessed by the amount of calcium released into the medium and the number of osteoclasts counted on light microscopy, was increased by both PTH and TE. On electron microscopy, areas for cytoplasm, ruffled border and clear zone were statistically increased in PTH- and TE-treated calvaria as compared to control. These values were not significantly different between PTH- and TE-treated calvaria. The study therefore demonstrates that the ultrastructural changes in osteoclasts induced by the hypercalcemia-producing TE are similar to those induced by PTH.

Effect of hypercalcemia-producing tumor on 1,25(OH)2D3 biosynthesis in athymic mice.

Serum 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] levels are low in patients with malignancy-associated hypercalcemia (MAH), whereas murine models of MAH have high circulating 1,25(OH)2D3. To determine the effects of a hypercalcemia-producing tumor on circulating 1,25(OH)2D3, in vitro 25-hydroxyvitamin D1-hydroxylase (1OHase) activity was measured in kidneys from BALB/c athymic mice implanted with a hypercalcemia-producing human lung tumor. Twelve days of low-phosphorus diet (LPD) in control animals lowered serum phosphorus to levels found in tumor-bearing mice fed normal phosphorus diet (NPD; 4.1 +/- 0.3 vs. 4.4 +/- 0.7 mg/dl, P = NS) and increased 1OHase activity (1.6 +/- 0.2 vs. 3.9 +/- 0.7 pmol.mg protein-1.5 min-1, NPD vs. LPD, P less than 0.05). 1OHase activity was greater in tumor-bearing animals fed NPD compared with control animals fed LPD (8.4 +/- 0.6 vs. 3.9 +/- 0.7 pmol.mg protein-1.5 min-1, P less than 0.01). High-phosphorus intake suppressed 1OHase activity in both control and tumor-bearing animals. Seven days of parathyroid hormone infusion in control animals fed NPD raised serum calcium (9.4 +/- 0.2 vs. 13.3 +/- 1.6 mg/dl, P less than 0.05) and suppressed 1OHase activity (0.25 +/- 0.02 vs. 0.02 +/- 0.002 pmol.mg protein-1.5 min-1, P less than 0.001). The inverse relationship of serum phosphorus and 1OHase activity was much steeper in the tumor-bearing animals, with greater enzyme activity at comparable levels of serum phosphorus. The present study indicates that 1) factors produced by the tumor stimulate 1OHase activity, and 2) hypophosphatemia is required for expression of enhanced enzyme activity.

Cis-platinum treatment for malignancy-associated humoral hypercalcemia in an athymic mouse model.

We have established a model for malignancy-associated humoral hypercalcemia (MAHH) in athymic mice, utilizing a human squamous cell lung carcinoma. In the present studies, we evaluated cis-platinum (DDP), a cytotoxic agent known to produce hypomagnesemia, and occasionally hypocalcemia, in the treatment of MAHH. Upon development of significant hypercalcemia, defined as serum calcium (Ca) greater than or equal to 11.5 mg/dl, tumor-bearing mice received either normal saline (NS) alone (1.5 ml/day, i.p.), or NS + DDP. The DDP was given as a single dose of 6 micrograms/g body weight i.p. Serum Ca was determined on day 6 in surviving mice (6 of 10 survived in the NS-alone group; 7 of 10 survived in the NS + DDP group). Serum Ca (mean +/- SE) decreased from 14.3 +/- 0.46 to a nadir of 12.7 +/- 0.33 mg/dl in the NS-alone group, and from 13.5 +/- 0.46 to a nadir of 10.4 +/- 0.48 mg/dl in the NS + DDP group. Nadir serum Ca levels were significantly lower in the NS + DDP group (P = 0.003). Three of 7 surviving NS + DDP mice achieved normocalcemia, whereas none of the NS-alone animals became normocalcemic. Tumor volumes increased in all animals. There was no change in the serum Ca in 5 tumor-free mice treated with NS + DDP. There were no significant differences in serum magnesium levels among groups of control mice, tumor-free mice treated with NS + DDP, tumor-bearing mice treated with NS + DDP, and tumor-bearing mice treated with NS-alone.(ABSTRACT TRUNCATED AT 250 WORDS)

A model for malignancy-associated humoral hypercalcemia.

Tumor tissue from a patient with squamous cell carcinoma of the lung and hypercalcemia has been serially implanted into athymic mice. Tumor-bearing mice develop cachexia, hypercalcemia without bone metastases, hypophosphatemia, increased urinary cyclic adenosine monophosphate (cAMP) to creatinine ratio, and undetectable human immunoreactive parathyroid hormone levels. Radiographs of spines in the tumor-bearing mice demonstrate demineralization, suggesting skeletal resorption as the source of the hypercalcemia. Within 4-8 hours following tumor removal, hypercalcemia is reversed, suggesting that a relatively short-acting humoral substance is responsible for the hypercalcemia. The animals gain weight and become essentially normal within 4 days following tumor removal. The studies demonstrate that this animal model is similar in many aspects to human malignancy-associated humoral hypercalcemia (MAHH) and can provide a useful tool for further investigation of the pathogenesis and treatment of this syndrome.