Inhibition of phosphatidylinositol 3-kinase signaling negates the growth advantage imparted by a mutant epidermal growth factor receptor on human glioblastoma cells

In de novo glioblastoma multiforme, loss of the tumour suppressor protein PTEN can coincide with the expression of a naturally occurring mutant epidermal growth factor receptor known as deltaEGFR. DeltaEGFR signals constitutively via the phosphatidylinositol 3-kinase (PI3K)/protein kinase Akt and mitogen-activated protein kinase pathways. In human U87MG glioblastoma cells that lack PTEN, deltaEGFR expression enhances tumourigenicity by increasing cellular proliferation. Inhibition of PI3K signaling with the pharmacologic inhibitor wortmannin, or by the reconstitution of physiological levels of PTEN to dephosphorylate the lipid products of PI3K, negated the growth advantage imparted by deltaEGFR on U87MG cells. PTEN reconstitution suppressed the elevated PI3K signaling, without affecting mitogen-activated protein kinase signaling and caused a delay in G1 cell cycle progression that was concomitant with increased cyclin-dependent protein kinase inhibitor p21CIP1/WAF1 protein levels. Our study provides insight into the mechanism by which deltaEGFR may contribute to glioblastoma development.

Second tumors after radiosurgery: tip of the iceberg or a bump in the road?

OBJECTIVE

Radiosurgery-associated second tumors have been reported in four isolated patients during the past 2 years. In our own experience, we are aware of two additional patients. The purpose of this report is to call attention to this potentially emerging problem.

METHODS

A review of the English-language literature concerning patients with radiosurgery-associated second tumors was performed. In addition, we report on two patients in our own practice who were treated in the past year.

RESULTS

Four patients were found in the literature, and two additional patients were seen by the authors. Malignant tumors occurred as early as 6 years after radiosurgery. The pathological findings in three of these four malignant tumors were glioblastoma multiforme. Benign tumors developed between 16 and 19 years later. Tumors developed both within the full-dose prescription volume and in the lower-dose periphery. Of interest, three of the six patients experienced complications of the radiosurgery treatment before developing second tumors.

CONCLUSION

Although patients will increasingly be reported with second tumors after radiosurgery in the future, the overall incidence seems quite low and should not alter current radiosurgical practice. However, continual surveillance of treated patients should be considered.

Glioblastoma in kidney transplant recipients. Report of five cases

Five patients who developed an intracranial glioblastoma after a kidney transplant are described. All patients underwent surgical removal of the lesion and eventually radiation therapy, but none of them is still alive at follow-up. The possibility of tumours occurring in transplant recipients is a recognised entity and several series have been reported. Nevertheless, little consideration has been paid to post-transplant gliomas and a precise evaluation of this risk is still lacking. Several hypotheses have been proposed to explain a possible link. One possible factor may be the immunosuppressive state of recipients as a result of post-transplant administration of immunosuppressive drugs, as it is known that gliomas have an higher incidence in HIV-infected patients. However, it is not yet clear whether immunosuppressive drugs function as a direct transforming factor.

Occupational head injury and subsequent glioma

We report the case of a policeman who suffered a severe head injury to the right temporoparietal lobe while driving a police car. Four years later, the patient developed a neoplasm at the precise site of the meningocerebral scar. Histological examination confirmed a glioblastoma multiforme adjacent to the dural scar. Radiological documentation of the absence of tumor at the time of injury, exact localization of the neoplasm in the injured cerebral area, and latency of the cancer supported the hypothesis of a causal relationship with brain trauma. Physicians faced with brain neoplasms in adults should carefully investigate the patient's personal history of head trauma. When a relationship with occupational head injury is probable, reporting of suspect occupational illness is compelling.

Molecular epidemiology of glioblastoma

Glioblastoma (GBM) is the most important primary brain tumor, both in terms of its incidence and its devastating impact on the unfortunate patients who have it. Although several well-defined hereditary syndromes predispose to malignant gliomas, most cases occur in the absence of a such a syndrome. The role of environmental factors, based on the known associations to date, also appears limited when compared with the total number of patients affected. It is clear that much remains to be discovered to better elucidate the causes of GBM, but the increasing recognition of molecular subtypes may help advance this field. This review highlights current insights into the molecular epidemiology of GBM.

Further aspects on cellular and cordless telephones and brain tumours

We included in a case-control study on brain tumours and mobile and cordless telephones 1,617 patients aged 20-80 years of both sexes diagnosed during January 1, 1997 to June 30, 2000. They were alive at the study time and had histopathology verified brain tumour. One matched control to each case was selected from the Swedish Population Register. The study area was the Uppsala-Orebro, Stockholm, Linköping and Göteborg medical regions of Sweden. Exposure was assessed by a questionnaire that was answered by 1,429 (88%) cases and 1,470 (91%) controls. In total use of analogue cellular telephones gave an increased risk with odds ratio (OR)=1.3, 95% confidence interval (CI)=1.04-1.6, whereas digital and cordless phones did not overall increase the risk significantly. Ipsilateral use of analogue phones gave OR=1.7, 95% CI=1.2-2.3, digital phones OR=1.3, 95% CI=1.02-1.8 and cordless phones OR=1.2, 95% CI=0.9-1.6. The risk for ipsilateral use was significantly increased for astrocytoma for all studied phone types, analogue phones OR=1.8,95% CI=1.1-3.2, digital phones OR=1.8, 95% CI=1.1-2.8, cordless phones OR=1.8, 95% CI=1.1-2.9. Use of a telephone on the opposite side of the brain was not associated with a significantly increased risk for brain tumours. Regarding anatomical area of the tumour and exposure to microwaves, the risk was increased for tumours located in the temporal area on the same side of the brain that was used during phone calls, significantly so for analogue cellular telephones OR=2.3, 95% CI=1.2-4.1. For acoustic neurinoma OR=4.4, 95% CI=2.1-9.2 was calculated among analogue cellular telephone users. When duration of use was analysed as a continuous variable in the total material, the risk increased per year for analogue phones with OR=1.04, 95% CI=1.01-1.08. For astrocytoma and ipsilateral use the trend was for analogue phones OR=1.10, 95% CI=1.02-1.19, digital phones OR=1.11, 95% CI=1.01-1.22, and cordless phones OR=1.09, 95% CI=1.01-1.19. There was a tendency of a shorter tumour induction period for ipsilateral exposure to microwaves than for contralateral, which may indicate a tumour promotor effect.

Synchronous occurrence of glioblastoma multiforme and esophageal adenocarcinoma

Synchronous malignancies are rare occurrences for which there may be a genetic link between two cancers or which may be simply coincidental. Although glioblastoma multiforme and esophageal adenocarcinoma have few clinical similarities there are no known biochemical or genetic links between the two malignancies. This case discussion details the synchronous occurrences of these two lesions and highlights possible clinical, biochemical, and genetic commonalities.

Induction of glioblastoma multiforme in nonhuman primates after therapeutic doses of fractionated whole-brain radiation therapy

OBJECT

To determine the acute and long-term effects of a therapeutic dose of brain radiation in a primate model, the authors studied the clinical, laboratory, neuroimaging, molecular, and histological outcomes in rhesus monkeys that had received fractionated whole-brain radiation therapy (WBRT).

METHODS

Twelve 3-year-old male primates (Macaca mulatta) underwent fractionated WBRT (350 cGy for 5 days/week for 2 weeks, total dose 3500 cGy). Animals were followed clinically and with laboratory studies and serial magnetic resonance (MR) imaging. They were killed when they developed medical problems or neurological symptoms, lesions appeared on MR imaging, or at study completion. Gross, histological, and molecular analyses were then performed. Nine (82%) of 11 animals that underwent long-term follow up (> 2.5 years) developed neurological symptoms and/or enhancing lesions on MR imaging, which were defined as glioblastoma multiforme (GBM), 2.9 to 8.3 years after radiation therapy. The GBMs were categorized as either unifocal (three) or multifocal (six), and were located in the supratentorial (six), infratentorial (two), or both (one) cranial regions. Histological examination revealed distant, noncontiguous tumor invasion within the white matter of all nine animals harboring GBMs. Novel interspecies comparative genomic hybridization (three animals) uniformly showed deletions in the GBMs that corresponded to chromosome 9 in humans.

CONCLUSIONS

The high rate of GBM formation (82%) following a therapeutic dose of WBRT in nonhuman primates indicates that radioinduction of these neoplasms as a late complication of this therapy may occur more frequently than is currently recognized in human patients. The development of these tumors while monitoring the monkeys' conditions with clinical and serial MR imaging studies, and access to the tumor and the entire brain for histological and molecular analyses offers an opportunity to gather unique insights into the nature and development of GBMs.

Genetic profile, PTEN mutation and therapeutic role of PTEN in glioblastomas

New therapeutic strategies are needed to improve survival in glioblastoma (GBM) the most malignant astrocytic tumor. We evaluated: a) the genetic status of 22 GBMs by comparative genomic hybridization (CGH); b) the specific role of mutation and/or homozygous deletion of PTEN in the genesis of GBM; and c) the possible therapeutic role of PTEN against GBM, in vitro. CGH demonstrated that the most frequent region of gain was at chromosome 7p, whereas the most frequent losses occurred at chromosomes 10q and 13q. Losses at chromosome 10 were found in 36% of patients, and PTEN was mutated in 27% of the 22 GBMs, including 4 point mutations and 2 homozygous deletions. The possible therapeutic role of PTEN in GBM was also studied in a system based on retroviral infection of the GBM cell line A172, homozygously deleted at the PTEN locus. A172 growth and proliferation rate were reduced by 50% after PTEN transduction. Moreover, we showed that inhibition of cell growth occurred through the PI3K/Akt/p27 pathway. Our findings suggest that PTEN participates in the genesis of GBM, and might be further studied as a candidate therapeutic agent in other testing systems.

Modelling normal tissue isoeffect distribution in conformal radiotherapy of glioblastoma provides an alternative dose escalation pattern through hypofractionation without reducing the total dose

The purpose of this study was to prove that by using conformal external beam radiotherapy (RT) normal brain structures can be protected even when applying an alternative approach of biological dose escalation: hypofractionation (HOF) without total dose reduction (TDR). Traditional 2-dimensional (2D) and conformal 3-dimensional (3D) treatment plans were prepared for 10 gliomas representing the subanatomical sites of the supratentorial brain. Isoeffect distributions were generated by the biologically effective dose (BED) formula to analyse the effect of conventionally fractionated (CF) and HOF schedules on both the spatial biological dose distribution and biological dose-volume histograms. A comparison was made between 2D-CF (2.0 Gy/day) and 3D-HOF (2.5 Gy/day) regimens, applying the same 60 Gy total doses. Integral biologically effective dose (IBED) and volumes received biologically equivalent to a dose of 54 Gy or more (V-BED54) were calculated for the lower and upper brain stem as organs of risk. The IBED values were lower with the 3D-HOF than with the 2D-CF schedule in each tumour location, means 22.7+/-17.1 and 40.4+/-16.9 in Gy, respectively (p < 0.0001). The V-BED54 values were also smaller or equal in 90% of the cases favouring the 3D-HOF scheme. The means were 2.7+/-4.8 ccm for 3D-HOF and 10.7+/-12.7 ccm for 2D-CF (p = 0.0006). Our results suggest that with conformal RT, fraction size can gradually be increased. HOF radiotherapy regimens without TDR shorten the treatment time and seem to be an alternative way of dose escalation in the treatment of glioblastoma.

NG2 proteoglycan promotes angiogenesis-dependent tumor growth in CNS by sequestering angiostatin

During embryogenesis, the NG2 proteoglycan is expressed on immature capillary vessels, but as the vessels mature they lose this expression. NG2 is up-regulated in high-grade gliomas, but it is not clear to what extent it contributes to malignant progression. Using a combination of high spatial and temporal resolution functional magnetic resonance imaging and histopathological analyses, we show here that overexpression of NG2 increases tumor initiation and growth rates, neovascularization, and cellular proliferation, which predisposes to a poorer survival outcome. By confocal microscopy and cDNA gene array expression profiles, we also show that NG2 tumors express lower levels of hypoxia inducible factor-1a, vascular endothelial growth factor, and endogenous angiostatin in vivo compared with wild-type tumors. Moreover, we demonstrate that NG2-positive cells bind, internalize, and coimmunoprecipitate with angiostatin. These results indicate a unique role for NG2 in regulating the transition from small, poorly vascularized tumors to large, highly vascular gliomas in situ by sequestering angiostatin.

[Malignant brain tumors after radiation - glioblastomas after operation and radiation of meningiomas - 2 case reports]

The authors report 2 cases of glioblastomas subsequent to radiation of intracranial tumors. In the first case, a 47-year old man received radiation therapy after subtotal removal of a temporobasal meningioma. In the second case, a 52-year old women underwent operation of an atypical falcine meningioma and was irradiated postoperatively. - After radiation of meningiomas the development of glioblastomas is described as a rare complication in the literature. A literature analysis of 49 radiation induced tumors revealed that there was no correlation between the radiation dosage and time interval of appearance of the second tumor.

Oxidant stress and glioblastoma multiforme risk: serum antioxidants, gamma-glutamyl transpeptidase, and ferritin

Case-control studies of serum antioxidants are difficult to interpret, because antioxidants may be altered by the disease under study. However, because glioblastoma multiforme (GBM) is a relatively rare disease, a cohort study would require a large sample observed for many years. In the present case-control pilot study (34 cases and 35 controls), we evaluated the association between serum levels of ascorbic acid (AA) and alpha- and gamma-tocopherol (alpha-T and gamma-T) measured before diagnostic surgery. To control for influence of GBM on serum AA, alpha-T, and gamma-T, we adjusted for oxidant stress indexes (gamma-glutamyl transpeptidase and uric acid) and an acute-phase response index (serum ferritin). When adjusted, AA is inversely related to GBM (p for trend = 0.007). In addition, AA interacts with alpha-T to further reduce GBM risk (test for interaction, p = 0.04). gamma-T is not associated with GBM (p = 0.71). However, gamma-glutamyl transpeptidase (p = 0.004), coenzyme Q (p = 0.01), and ferritin (p = 0.009) are positively and uric acid (p = 0.000) is negatively related to GBM. We conclude that 1) AA and alpha-T are jointly related to GBM after adjustment for GBM-produced oxidant stress and 2) there is a strong association between the presence of GBM and oxidant stress.

Radiosurgery-induced brain tumor. Case report

The authors describe a case of glioblastoma multiforme (GBM) associated with previous gamma knife radiosurgery for a cerebral arteriovenous malformation (AVM). A 14-year-old boy had undergone radiosurgery for an AVM, which was performed using a 201-source 60Co gamma knife system at another institution. The maximum and margin radiation doses used in the procedure were 40 and 20 Gy, respectively. One year after radiosurgery, the patient noticed onset of mild left hemiparesis due to radiation necrosis. Six and one-half years after radiosurgery, at the age of 20 years, the patient experienced an attack of generalized tonic-clonic seizure. Magnetic resonance (MR) imaging revealed the existence of a brain tumor in the right parietal lobe. The patient underwent an operation and the histological diagnosis of the lesion was GBM. Ten months following the operation, that is, 99 months postradiosurgery, this patient died. To the best of the authors' knowledge, this is the first reported case of a neoplasm induced by radiosurgery for an AVM and the second case in which it occurred following radiosurgery for intracranial disease.

[A case showing effective radiotherapy for a radiation-induced glioblastoma]

Radiation-induced glioblastoma is usually resistant to all treatments. We report a case with radiation-induced glioblastoma, in which radiotherapy was remarkably effective. A 14-year-old female with a history of acute lymphoblastic leukemia, at the age of 7, underwent 15 Gy of radiotherapy to the whole brain. She was admitted to our department due to the development of headache and nausea. Magnetic resonance imaging showed an irregularly enhanced mass in the left frontal lobe. Partial removal of the mass was performed and histological examination showed it to be glioblastoma with a high MIB-1 index. The patient underwent 40 Gy of local radiotherapy and chemotherapy with ACNU and Interferon-beta for 2 years. The residual tumor disappeared after the radiotherapy, and her status is still "complete remission", 29 months after the onset.

Hyperprolactinaemia and prolactin binding in benign intracranial tumours

BACKGROUND

Meningiomas have been found to have receptors for several hormones, such as oestrogen, progesterone, somatostatin, dopamine and recently also for prolactin.

METHODS

To investigate any possible role of prolactin in the growth of those tumours we detected the presence of prolactin-receptors (PRL-R) in 22 meningiomas and we correlated these data with PRL serum levels in patients before surgery. We also studied 13 patients with schwannomas and 7 with other cerebral tumours (4 glioblastomas, 2 ependymomas and 1 astrocytoma).

RESULTS

Increased prolactin binding was present in 10 (45.4 percent;) meningiomas, 9 (69.2 percent;) schwannomas and in the patient with astrocytoma. The presence of high PRL levels was present in 6 (27.2 percent;) patients with meningiomas, 8 (61.5 percent;) with schwannomas and in 3 (42.8 percent;) with other tumours. No direct correlation was present between serum PRL levels and PRL binding in all groups.

CONCLUSIONS

In conclusion we confirmed the presence of PRL receptors in patients with meningiomas and we have also shown the presence of PRL receptors also in schwannomas. Moreover increased serum PRL were shown in some patients with different tumours of nervous tissue before surgery. Our data could suggest that PRL might have a role in the growth of meningiomas and schwannomas.

Glioblastoma multiforme occurring in a patient treated with gamma knife surgery

✓ Stereotactic radiosurgery is being increasingly advocated as the primary modality for treatment of vestibular schwannomas (VS). This modality has been shown to arrest tumor growth, with few associated short-term morbidities, and with possibly better hearing and facial nerve preservation rates than microsurgery. Radiation-induced oncogenesis has long been recognized, although stereotactic radiosurgery de novo induction of a secondary tumor has never been clearly described. The authors report on a patient with a VS who did not have neurofibromatosis Type 2 and who underwent gamma knife surgery (GKS). This patient required microsurgical removal of the VS within 8 months because of development of a tumor cyst with associated brainstem compression and progressive hydrocephalus. The operation resulted in clinical stabilization and freedom from tumor recurrence.

Seven and a half years after undergoing GKS, the patient presented with symptoms of raised intracranial pressure. Magnetic resonance imaging demonstrated a new ring-enhancing lesion in the inferior temporal lobe adjacent to the area of radiosurgery, which on craniotomy was confirmed to be a glioblastoma multiforme (GBM). Despite additional conventional external-beam radiation to the temporal lobe, the GBM has progressed. Whereas this first reported case of a GBM within the scatter field of GKS does not conclusively prove a direct causal link, it does fulfill all of Cahan's criteria for radiation-induced neoplasia, and demands increased vigilance for the potential long-term complications of stereotactic radiosurgery, and reporting of any similar cases.

Aspects of intracranial and spinal tumors in patients with Down syndrome and report of a rapidly progressing Grade 2 astrocytoma

BACKGROUND

Brain tumors in patients with Down syndrome (DS) rarely are reported, and their behavior is not well known.

METHODS

The authors report on a male patient age 19 years who had DS with diffuse astrocytoma (World Health Organization Grade 2) that recurred twice despite treatment, leading to a glioblastoma and, finally, to death in just over 2 years. The literature on brain tumors in patients with DS is reviewed.

RESULTS

Although brain neoplasms were suspected to be in excess in patients with DS, the authors found only 36 patients with brain neoplasms and 2 spinal tumors. An unusual distribution of histologic tumor types, with an over-representation of germ cell and mesenchymal tumors and a lack of embryonal tumors, was observed, in agreement with what is known currently about the tumor profile of patients with DS.

CONCLUSIONS

Cerebral tumors in patients with DS have a specific distribution and may behave differently compared with the general population. These features may be related to the gene dosage effect of oncogenes, antioncogenes, and genes involved in cerebral development due to the supernumerary chromosome 21.

Glycosylation-induced conformational modification positively regulates receptor-receptor association: a study with an aberrant epidermal growth factor receptor (EGFRvIII/DeltaEGFR) expressed in cancer cells

The epidermal growth factor receptor (EGFR) is a multisited and multifunctional transmembrane glycoprotein with intrinsic tyrosine kinase activity. Upon ligand binding, the monomeric receptor undergoes dimerization resulting in kinase activation. The consequences of kinase stimulation are the phosphorylation of its own tyrosine residues (autophosphorylation) followed by association with and activation of signal transducers. Deregulation of signaling resulting from aberrant expression of the EGFR has been implicated in a number of neoplasms including breast, brain, and skin tumors. A mutant epidermal growth factor (EGF) receptor missing 267 amino acids from the exoplasmic domain is common in human glioblastomas. The truncated receptor (EGFRvIII/DeltaEGFR) lacks EGF binding activity; however, the kinase is constitutively active, and cells expressing the receptor are tumorigenic. Our studies revealed that the high kinase activity of the DeltaEGFR is due to self-dimerization, and contrary to earlier reports, the kinase activity per molecule of the dimeric DeltaEGFR is comparable to that of the EGF-stimulated wild-type receptor. Furthermore, the phosphorylation patterns of both receptors are similar as determined by interaction with a conformation-specific antibody and by phosphopeptide analysis. This eliminates the possibility that the defective down-regulation of the DeltaEGFR is due to its altered phosphorylation pattern as has been suggested previously. Interestingly, the receptor-receptor self-association is highly dependent on a conformation induced by N-linked glycosylation. We have identified four potential sites that might participate in self-dimerization; these sites are located in a domain that plays an important role in EGFR functioning.

Glioblastoma induction after radiosurgery for meningioma

A 70-year-old woman developed a glioblastoma in the irradiated field 7 years after stereotactic radiosurgery for meningioma. Glioma induction has been previously reported after external beam radiation for leukaemia, pituitary adenoma, tinea capitus, and meningioma. This radiosurgery-induced malignancy may portend further reports of tumour induction. The theoretical risk of tumour induction by low doses of radiation to normal neural tissue after radiosurgery is now confirmed. Reports of additional cases of radiosurgery-induced tumours might temper the use of this increasingly used technique for benign surgically accessible lesions.

Occupation and adult gliomas

Lifetime job histories from a population-based, case-control study of gliomas diagnosed among adults in the San Francisco Bay area between August 1991 and April 1994 were evaluated to assess occupational risk factors. Occupational data for 476 cases and 462 controls were analyzed, with adjustment for age, gender, education, and race. Imprecise increased risks were observed for physicians and surgeons (odds ratio (OR) = 3.5, 95% confidence interval (CI): 0.7, 17.6), artists (OR = 1.9, 95% CI: 0.5, 6.5), foundry and smelter workers (OR = 2.6, 95% CI: 0.5, 13.1), petroleum and gas workers (OR = 4.9, 95% CI: 0.6, 42.2), and painters (OR = 1.6, 95% CI: 0.5, 4.9). Legal and social service workers, shippers, janitors, motor vehicle operators, and aircraft operators had increased odds ratios only with longer duration of employment. Physicians and surgeons, foundry and smelter workers, petroleum and gas workers, and painters showed increased risk for both astrocytic and nonastrocytic tumors. Artists and firemen had increased risk for astrocytic tumors only, while messengers, textile workers, aircraft operators, and vehicle manufacturing workers showed increased risk only for nonastrocytic tumors. Despite study limitations, including small numbers for many of the occupational groups, a high percentage of proxy respondents among cases, and lack of specific exposure information, associations were observed for several occupations previously reported to be at higher risk for brain tumors generally and gliomas specifically.

[Radiation-induced glioblastoma and myxoma after treatment for undifferentiated carcinoma of the naspharynx]

Radio-induced tumor have been known for a long time to occur after treatment of cancer during childhood. This entity is exceptional following radiotherapy of the cavum. Skull and facial osteosarcoma were described after treatment of UCNT. We report two observations of radio-induced tumors arising, respectively three and seven years after treatment of UCNT. The first one is a temporoparietal glioblastoma and the second is a rhino- and pharyngeal myxoma. The two patients are alive after treatment of the second tumor. The delay of appearance of these tumors, their situation in the field's irradiated and dose received suggests their radio-induced nature. However, the cytogenetic study is necessary to confirm the implication of radiotherapy in the genesis of these cancers.