Glypican-3 expression in Wilms tumor and hepatoblastoma

BACKGROUND

Glypican-3 (GPC3) is a heparan sulfate proteoglycan. When it is disrupted, it causes the X-linked gigantism-overgrowth Simpson-Golabi-Behmel syndrome. Its involvement in growth control is consistent with recent reports that it can bind to growth factors, possibly including insulin-like growth factor 2. Further, it has been hypothesized that it may function as a tumor suppressor gene in breast and ovarian carcinomas and mesotheliomas.

PATIENTS AND METHODS

RNA and protein were extracted from Wilms tumor and hepatoblastoma tissue samples and GPC3 levels were measured in these extracts by Northern blotting, reverse transcription polymerase chain reaction, and immunoblotting.

RESULTS

In contrast to published results with carcinomas, high levels of GPC3 expression were found in Wilms tumor and hepatoblastoma. Low or undetectable expressions of this gene were found in normal tissue surrounding the tumor.

CONCLUSIONS

Increased expression of GPC3 in Wilms tumor and hepatoblastoma suggests a growth-promoting or neutral activity for this gene product rather than a growth-suppressive effect.

Primary follicular large cell lymphoma of the testis in a child

Primary follicular lymphoma of the testis in childhood is extremely rare. To our knowledge, only 5 cases have been reported to date. We report a case in a 6-year-old boy who presented with painless right scrotal enlargement. Right radical orchiectomy revealed a follicular large cell lymphoma with diffuse areas confined to the testis and epididymis, clinical stage IE. Immunohistochemical stains demonstrated that the neoplastic cells were of B-cell lineage, positive for CD10, CD20, CD79a, and BCL-6. Staining for CD21 accentuated networks of dendritic reticulum cells within the nodules. The cells were negative for BCL-2, p53, and T-cell antigens. There was no evidence of the t(14;18) detected by polymerase chain reaction. The data suggest that follicular lymphoma of the testis in children has a different pathogenesis than follicular lymphoma in adults.

Inhibition of N-myc expression and induction of apoptosis by iron chelation in human neuroblastoma cells

Neuroblastoma is the second most common solid malignancy of childhood. Enhanced expression of the amplified N-myc gene in the tumor cells may be associated with poor patient prognosis and may contribute to tumor development and progression. The use of deferoxamine mesylate (DFO), an iron chelator, to treat neuroblastoma is being investigated in national clinical studies. We show here by TUNEL assay and DNA laddering that DFO induces apoptosis in cultured human neuroblastoma cells, which is preceded by a decrease in the expression of N-myc and the altered expression of some other oncogenes (up-regulating c-fos and down-regulating c-myb) but not housekeeping genes. The decrease in N-myc expression is iron-specific but does not result from inhibition of ribonucleotide reductase, because specific inhibition of this iron-containing enzyme by hydroxyurea does not affect N-myc protein levels. Nuclear run-on and transient reporter gene expression experiments show that the decrease in N-myc expression occurs at the level of initiation of transcription and by inhibiting N-myc promoter activity. Comparison across neuroblastoma cell lines of the amount of residual cellular N-myc protein with the extent of apoptosis measured as pan-caspase activity after 48 h of iron chelation reveals no correlation, suggesting that the decrease in N-myc expression is unlikely to mediate apoptosis. In conclusion, chelation of cellular iron by DFO may alter the expression of multiple genes affecting the malignant phenotype by multiple pathways. Given the clinical importance of N-myc overexpression in neuroblastoma malignancy, decreasing N-myc expression by DFO might be useful as an adjunct to current

Recognition of common childhood malignancies

Although cancer has an annual incidence of only about 150 new cases per 1 million U.S. children, it is the second leading cause of childhood deaths. Early detection and prompt therapy have the potential to reduce mortality. Leukemias, lymphomas and central nervous system tumors account for more than one half of new cancer cases in children. Early in the disease, leukemia may cause nonspecific symptoms similar to those of a viral infection. Leukemia should be suspected if persistent vague symptoms are accompanied by evidence of abnormal bleeding, bone pain, lymphadenopathy or hepatosplenomegaly. The presenting symptoms of a brain tumor may include elevated intracranial pressure, nerve abnormalities and seizures. A spinal tumor often presents with signs and symptoms of spinal cord compression. In children, lymphoma may present as one or more painless masses, often in the neck, accompanied by signs and symptoms resulting from local compression, as well as signs and symptoms of systemic disturbances, such as fever and weight loss. A neuroblastoma may arise from sympathetic nervous tissue anywhere in the body, but this tumor most often develops in the abdomen. The presentation depends on the local effects of the solid tumor and any metastases. An abdominal mass in a child may also be due to Wilms' tumor. This neoplasm may present with renal signs and symptoms, such as hypertension, hematuria and abdominal pain. A tumor of the musculoskeletal system is often first detected when trauma appears to cause pain and dysfunction out of proportion to the injury. Primary care physicians should be alert for possible presenting signs and symptoms of childhood malignancy, particularly in patients with Down syndrome or other congenital and familial conditions associated with an increased risk of cancer.

Phosphoinositide 3-hydroxide kinase blockade enhances apoptosis in the Ewing's sarcoma family of tumors

Ewing's sarcoma family of tumors (ESFTs) affects patients between the ages of 3 and 40 years, with most cases occurring in the second decade of life. These tumors contain a characteristic translocation, t(11;22), that produces a unique fusion protein, EWS/FLI-1. EWS/FLI-1 transforms mouse fibroblasts; this transformation requires intact EWS and FLI-1 domains as well as the insulin-like growth factor-I receptor (IGF-IR). The IGF-IR is a well-described transmembrane tyrosine kinase receptor that modulates transformation, cell growth, and survival. IGF-IR survival signaling is mediated through the downstream activation of phosphoinositide 3-OH kinase (PI 3-K) and Akt. Apoptosis, programmed cell death, progresses from a central death signal to a caspase cascade, including activation of caspase-3. Because the IGF-IR has been shown to play a role in the transformation and growth of ESFTs, we wanted to determine the role of downstream molecules in the cellular response to doxorubicin treatment. Doxorubicin increased caspase-3 activity in two ESFT cell lines, TC-32 and TC-71. Concomitant treatment of the doxorubicin-treated cells with IGF-I reduced caspase-3 activity 8-fold in TC-32 and 4-fold in TC-71. To determine whether PI 3-K has a role in IGF-I-mediated survival in ESFTs, PI 3-K was then inhibited with wortmannin and LY294002. Doxorubicin treatment reduced cell number and enhanced apoptosis in PI 3-K inhibited cells compared with noninhibited cells. Akt, a serine/threonine kinase activated downstream of PI 3-K, was investigated to determine whether its constitutive activation would render ESFT cells more resistant to doxorubicin. A constitutively activated Akt was stably transfected into ESFT and those cells with high levels of expression demonstrated increased resistance to doxorubicin-induced caspase-3 activation. These results indicate that ESFT cell lines use an IGF-IR initiated signaling pathway through PI 3-K and Akt for survival when treated with doxorubicin.

Cerebral edema and priapism in an adolescent with acute lymphoblastic leukemia

Priapism and increased intracranial pressure are both rare, but recognized, manifestations of leukemia. However, they have never been reported in the same patient. We report a 15-year-old male with acute lymphoblastic leukemia who presented with hyperleukocytosis, priapism, and increased intracranial pressure. Central nervous system leukostasis and cerebral edema may have been detected earlier, had his history of priapism been known. Management of hyperleukocytosis complicated by priapism and increased intracranial pressure is discussed.

Induction of heat shock protein 27 by hydroxyurea and its relationship to experimental metastasis

Treatment of tumor cells with hydroxyurea (HU) has been shown to increase the experimental metastatic potential of these cells. We have previously described the induction of stress proteins (antioxidants) by HU in B16 murine melanoma cells and their relationship to the metastatic process. We have now investigated the induction by HU of another set of stress proteins, the heat shock proteins, and their role in experimental metastasis. HU markedly increased the cellular content of heat shock protein (hsp) 27 but not of hsp 90, 72/73, or 60 as measured by immunoblotting. The induction of hsp27 protein was preceded by a specific increase in hsp27 mRNA. Furthermore, HU-treated cells were more thermotolerant. To investigate the functional role of hsp27, human hsp27 cDNA was constitutively overexpressed in B16 cells at levels seen in HU-treated cells. In separate experiments, we induced a global increase in hsps by heat shock. Neither the hsp27 transfectants nor the heat-shocked cells demonstrated an increase in their experimental metastatic capacity. We conclude that hsp27 protein is increased by HU by the specific induction of hsp27 mRNA in B16 melanoma cells but increased hsp27 protein is not responsible for the increase in experimental metastasis. Since high levels of hsp27 are associated with metastatic disease in breast and ovarian cancers, but not in our experimental system, the functional role of hsp27 in metastasis requires further study.

Role of antioxidant enzymes in the induction of increased experimental metastasis by hydroxyurea

BACKGROUND

Treatment of tumor cells with hydroxyurea and other DNA-damaging agents has been shown to increase the experimental metastatic potential of these cells.

PURPOSE

We sought to elucidate some of the biochemical and genetic changes that promote tumor cell metastasis in hydroxyurea-treated cells. We hypothesized that drug treatment induces resistance to oxidative damage and that elimination of this resistance reverses the drug-induced experimental metastatic capabilities of tumor cells.

METHODS

We examined the effect of hydroxyurea treatment on B16 melanoma cells with respect to experimental metastatic potential, resistance to hydrogen peroxide (H2O2), glutathione peroxidase activity and messenger RNA (mRNA) level, glutathione reductase activity, glutathione levels, glutathione-S-transferase activity, and catalase activity and mRNA level.

RESULTS

Hydroxyurea-treated cells were transiently more metastatic following intravenous injection in syngeneic mice and transiently more resistant than untreated cells to exogenous H2O2. Hydroxyurea-induced experimental metastases and H2O2 resistance were eliminated by depletion of intracellular glutathione with buthionine sulfoximine. Glutathione peroxidase activity and mRNA level, glutathione reductase activity, and reduced glutathione levels were all transiently increased in hydroxyurea-treated cells, whereas the increase in glutathione-S-transferase activity was sustained. Catalase activity was modestly increased with no increase in its mRNA levels.

CONCLUSIONS

In B16 melanoma cells, experimental metastasis induced by hydroxyurea appears to depend on a process that requires glutathione. Hydroxyurea treatment also induces resistance to exogenous H2O2, which may be due to induction of glutathione and antioxidant enzyme activity.

IMPLICATIONS

The role of antioxidants in B16 melanoma cells offers new insights into the metastatic process and the cellular response to chemotherapy.

Therapy for childhood acute lymphoblastic leukemia

Recent advances in therapy for childhood acute lymphoblastic leukemia have come primarily from the intensive laboratory study of patient's lymphoblasts. DNA-ploidy determination, the analysis of specific chromosomal translocations, and in vitro chemosensitivity studies now facilitate the stratification of risk groups and the prediction of treatment outcome. More is known about the heterogeneity of molecular defects involved in leukemogenesis, and this information is being exploited to devise sensitive tests for minimal residual disease. Conventional chemotherapy of childhood acute lymphoblastic leukemia is associated with adverse neuropsychological sequelae and second malignancies when intensive epipodophyllotoxin therapy is used. Treatment of relapsed acute lymphoblastic leukemia remains problematic. The development of alternative donor marrow sources will expand the role of bone marrow transplantation, which has provided better outcomes for a limited number of patients. We are still waiting to spawn novel therapeutic agents that are more effective and less toxic than present chemotherapy.

Vascular anatomy and organ-specific tumor growth as critical factors in the development of metastases and their distribution among organs

We have examined with 19 tumor cell lines the discrete roles that vascular anatomy and tumor-cell-organ-affinity play in the development of metastases and their distribution among organs. Spontaneous metastases of B16-G3.26 melanoma cells from a primary tumor growing in the foot pad of mice, or experimental metastases 21 days after intravenous tumor-cell injection resulted in tumor colonies only in the lungs. In contrast, when the lung microvasculature was bypassed, and the same cells given by systemic intra-arterial (s.i.a.) injection, large tumor colonies developed selectively in the ovaries, adrenal glands and bones, but rarely in the lungs. When animals injected i.v. were allowed to live with lung metastases for a long period of time, small tumor colonies began to develop in extra-pulmonary organs with a distribution identical to that seen after s.i.a. injection. Seven murine tumor cell lines (previously characterized by their ability to colonize primarily the lungs after i.v. injection) and 7 of the 8 studied human tumor cell lines colonized different specific extra-pulmonary organs after s.i.a. injection, frequently producing metastatic syndromes commonly described in patients with cancer, but rarely seen in animal models of metastasis. These results suggest that metastatic cells, even those capable of colonizing specific organs, do not freely circulate in the blood stream and lodge in specific tissues. In contrast, the cells must establish a vascular route of access to the target organ, e.g., through the systemic circulation from metastatic tumors in the lungs. Two cell lines considered to be tumorigenic but non-metastatic failed to colonize the lungs or extra-pulmonary organs after i.v. injection, but readily colonized specific organs after s.i.a. injection. Thus, tumor cells considered to be non-metastatic may be indeed metastatic if they are provided with vascular access to an organ more congenial to their growth requirements.

Normalization of plasma arginine vasopressin concentrations when children with meningitis are given maintenance plus replacement fluid therapy

We hypothesized that plasma arginine vasopressin (AVP) concentrations in children with meningitis are appropriate for the children's degree of hypovolemia, even though the concentrations were higher than expected for the serum osmolality. A randomized study was conducted to compare the effect on plasma AVP concentrations of giving maintenance fluid requirements plus replacement of any deficit versus restricting fluids to two thirds of maintenance requirements for 24 hours. Plasma AVP concentrations and serum osmolality were measured before fluid therapy was begun and again after 24 hours. Nineteen children, 2 months to 17 years of age, were studied; 13 had bacterial meningitis (12 with Haemophilus influenzae type b). Ten children (seven with bacterial meningitis) received a mean of 1.42 times the calculated maintenance fluid requirements, and nine (six with bacterial meningitis) were restricted to a mean of 0.65 times maintenance. Children in the maintenance group also received significantly more sodium (mean = 6.3 mEq/kg/24 hr) than children in the fluid-restricted group (mean = 2.0 mEq/kg/24 hr). The two groups were comparable for plasma AVP concentration and serum osmolality before fluid therapy was begun. The plasma AVP concentration was significantly lower after 24 hours of maintenance plus replacement fluids than after fluid restriction (p = 0.005), and the change in AVP concentration correlated with the amount of sodium given (p less than 0.02). This study supports the hypothesis that serum AVP concentrations are elevated in patients with meningitis because of hypovolemia and become normal when sufficient sodium is given to facilitate reabsorption of water by the proximal tubule of the kidney. Patients with meningitis can be given maintenance plus replacement fluids but should be monitored for the development of the syndrome of inappropriate secretion of antidiuretic hormone.