First spinal axis segment irradiation with spot-scanning proton beam delivered in the treatment of a lumbar primitive neuroectodermal tumour. Case report and review of the literature.

Primary intraspinal primitive neuroectodermal tumour (PNET) is a rare tumour entity. The optimal therapeutic management is unclear but, in general, this tumour is treated with surgery followed by radiotherapy and chemotherapy. Proton beam radiation therapy (PT) offers superior dose distributional qualities compared with X- or gamma rays, as the dose deposition occurs in a modulated narrow zone called the Bragg peak. As a result, organs at risk are optimally speared. Here, we present a patient treated with the first spinal axis segment irradiation using spot-scanning PT with a single field, combined with conventional cranio-spinal axis radiotherapy after surgery and chemotherapy, and an extensive review of the literature outlining the clinical features and treatment modality of spinal PNET.

Altered apoptotic profiles in irradiated patients with increased toxicity.

PURPOSE: A retrospective study of radiation-induced apoptosis in CD4 and CD8 T-lymphocytes, from 12 cancer patients who displayed enhanced toxicity to radiation therapy and 9 ataxia telangiectasia patients, was performed to test for altered response compared to healthy blood-donors and normal cancer patients. METHODS AND MATERIALS: Three milliliters of heparinized blood from each donor was sent via express post to the Paul Scherrer Institute (PSI) for subsequent examination. The blood was diluted 1:10 in RPMI medium, irradiated with 0-, 2-, or 9-Gy X-rays, and incubated for 48 h. CD4 and CD8 T-lymphocytes were then labeled using FITC-conjugated antibodies, erythrocytes were lysed, and the DNA stained with propidium iodide. Subsequently, cells were analyzed using a Becton Dickinson FACScan flow cytometer. Radiation-induced apoptosis was recognized in leukocytes as reduced DNA content attributed to apoptosis-associated changes in chromatin structure. Apoptosis was confirmed by light microscopy, electron microscopy, and by the use of commercially available apoptosis detection kits (in situ nick translation and Annexin V). Data from hypersensitive individuals were compared to a standard database of 105 healthy blood-donors, and a database of 48 cancer patient blood donors who displayed normal toxicity to radiation therapy. To integrate radiosensitivity results from CD4 and CD8 T-lymphocytes after 2 and 9 Gy, z-score analyses were performed. RESULTS: A cohort of 12 hypersensitive patients was evaluated; 8 showed enhanced early toxicity, 3 showed enhanced late toxicity, and 1 showed both. The cohort displayed less radiation-induced apoptosis (-1.8 sigma) than average age-matched donors. A cohort of 9 ataxia telangiectasia homozygotes displayed even less apoptosis (-3.6 sigma). CONCLUSION: The leukocyte apoptosis assay appears to be a useful predictor of individuals likely to display increased toxicity to radiation therapy; however, validation of this requires a prospective study.

Dexamethasone-induced enhancement of resistance to ionizing radiation and chemotherapeutic agents in human tumor cells.

BACKGROUND: Dexamethasone-induced changes in radioresistance have previously been observed by several authors. Here, we examined effects of dexamethasone on resistance to ionizing radiation in 10 additional human cell lines and strains, and on resistance to carboplatin and paclitaxel in 13 fresh tumor samples. MATERIAL AND METHODS: Eight human carcinoma cell lines, a glioblastoma cell line and a strain of normal human diploid fibroblasts were arbitrarily chosen for these in-vitro studies. Effects on radiosensitivity were assessed using a conventional colony formation assay. Effects on resistance to the drugs were investigated prospectively (ATP cell viability assay) using 13 fresh tumor samples from consecutive patients operated for ovarian cancer within the context of a Swiss nation-wide randomized prospective clinical trial (SAKK 45/94). RESULTS: Dexamethasone promoted proliferation of 1 of the cell lines without affecting radiosensitivity, while it completely inhibited proliferation of another cell line (effects on radiosensitivity could thus not be examined). Furthermore, dexamethasone induced enhanced radioresistance in 1 of the 8 carcinoma cell lines examined. In the glioblastoma cell line, there was no effect on growth or radioresistance, nor in the fibroblasts. Treatment with dexamethasone enhanced resistance of the malignant cells to carboplatin in 4 of the 13 fresh tumor samples examined, while no enhancement in resistance to paclitaxel was observed. CONCLUSIONS: In agreement with previous reports, we found that dexamethasone may induce radioresistance in human carcinoma cells. Including the published data from the literature, dexamethasone induced enhancement in radioresistance in 4 of 12 carcinoma cell lines (33%), but not in 3 glioblastoma cell lines, nor in 3 fibroblast strains. Dexamethasone also induced enhanced resistance to carboplatin with a similar probability in fresh samples of ovarian cancer evaluated prospectively (in 4 of 13 samples; 31%). We worry that induction of resistance by corticosteroids given to patients undergoing either radiotherapy or chemotherapy with agents causing DNA damage might be associated with a reduced clinical responsiveness in a significant fraction of patients with a carcinoma.

A biophysical basis of enhanced interstitial fluid pressure in tumors.

It is widely accepted that enhanced interstitial fluid pressure (IFP) in tumors is a major obstacle against delivery of therapeutic agents. On the other hand, the origin of enhanced IFP remains controversial. Here, the Van't Hoff equation is applied to examine how glucose breakdown to CO2 and lactate in tumor cells may affect intracellular osmotic pressure. According to the equation, it is found that production of CO2 from glucose lowers osmotic pressure inside cells, while glycolytic production of lactate generates significant increases. Crucial to a net enhancement of pressure in cells is the Warburg ratio, the ratio of the fraction of glucose transformed to lactate divided by the fraction of glucose metabolized to CO2: if (and only if) the ratio is higher than 1.0, there is a resulting increase in intracellular osmotic pressure. Under fully anaerobic glycolysis, the enhancement of intracellular pressure is maximal, namely 19.3 mmHg per mM of glucose metabolized to lactate (Van't Hoff equation). Cells are then biological pressure pumps driven by glycolytic production of lactate, causing IFP to raise. It is proposed that a regulatory feedback loop prevents IFP to raise above microvascular pressure (MVP). Accordingly, enhanced IFP in tumors is the result of high rates of tumor glycolysis, and enhancement of IFP is limited by MVP. It is thus concluded that a high rate of glycolytic production of lactate in tumor cells ultimately prevents both access of therapeutic agents to the malignant cells and immunological surveillance, and that it indirectly drives outward currents of interstitial fluid, thereby propelling both the process of tumor infiltration of surrounding structures and metastatic spread, depending on deformability and proteolytic capacity of the malignant cells.

Dexamethasone-induced radioresistance occurring independent of human papilloma virus gene expression in cervical carcinoma cells.

BACKGROUND: Inactivation of p53 by binding to simian virus 40-T antigen (SV40-T) and human papilloma virus type 16 protein E6 (HPV 16 E6) in transfected human diploid fibroblasts causes enhanced radioresistance. The aim of this study was to investigate the role of HPV 18 E6 and E7 gene products with respect to radiosensitivity of two cervical carcinoma cell lines. MATERIALS AND METHODS: The two cervical carcinoma lines C4-1 and SW 756 were used in which treatment with dexamethasone allows to modulate expression levels of HPV 18 E6 and E7 genes: upregulation in C4-1, downregulation in SW 756. Effects of treatment with dexamethasone on plating efficiency and radiosensitivity were assessed using a clonogenic assay. RESULTS: Treatment with dexamethasone increased plating efficiency of the C4-1 cells, but did not affect plating efficiency of SW 756 cells. Treatment with dexamethasone induced enhanced radioresistance in both cell lines. Thus in C4-1 cells the observed changes in radioresistance correlate to the enhancement in expression of HPV 18 genes E6/E7, whereas in SW 756, a reduced expression correlates negatively with the enhanced radioresistance. CONCLUSIONS: In C4-1 and SW 756 cells, treatment with dexamethasone induces radioresistance, and changes in expression levels of HPV 18 genes E6 and E7 do not correlate with the changes in radiosensitivity. Dexamethasone-induced radioresistance has previously been observed in HeLa cells, another human cervical carcinoma cell line. This leads us to speculate that dexamethasone-induced radioresistance may be important in certain clinical situations, and that therefore, the phenomenon deserves further study.

Prognostic factors associated with loss of heterozygosity at the RB1 locus in retinoblastoma.

The nature of the tumorigenic mutation was analyzed in 30 retinoblastoma (Rb) tumors (16 non-hereditary and 14 hereditary) and categorized into loss of heterozygosity (LOH) or retention of heterozygosity (non-LOH) at the RB1 locus. These genotypic characteristics were compared with the clinicopathological phenotype for possible correlation. The overall frequency of LOH was roughly 55%, in both hereditary and non-hereditary Rb. The presence of LOH was preferentially associated with differentiated tumors and absence of choroidal invasion. LOH was found in 82% of females versus 33% of males. Finally, LOH-initiated tumors were associated with a significantly younger age at diagnosis in hereditary Rb. In conclusion, the preferential association of LOH with absence of choroidal invasion, tumoral differentiation, and younger age at diagnosis may establish LOH as a prognostic marker in Rb patients.

Exogenous lactate interferes with cell-cycle control in Balb/3T3 mouse fibroblasts.

PURPOSE: Previous studies have shown that exogenous lactate may influence proliferation rates, radiation sensitivity, and postirradiation repair capacity of mammalian cells. In the present study, we addressed the question of potential underlying mechanisms and, therefore, examined effects of exogenous lactate on proliferation rates and cell-cycle distribution in immortal but nontumorigenic mammalian cells. METHODS AND MATERIALS: Cells were grown at 37 degrees C in an incubator with 5% CO2 and 95% air, in a culture medium supplemented or not with lactate at a 10 mM concentration. Daily, we changed the culture medium and counted cells per dish. On selected days, cell-cycle distribution was determined by flow cytometry. Balb/3T3 mouse fibroblasts were used. RESULTS: During the exponential phase of cell proliferation, mean population doubling time was significantly increased from 17.7 to 19.9 h, due to selective prolongation of G2/M. However, in density-inhibited cultures, exogenous lactate stimulated entry into S and proliferation to a significantly higher saturation density. CONCLUSIONS: These findings indicate that exogenous lactate interferes with mechanisms of cell-cycle control at two different points in the cell-cycle, depending on cell density and the resulting absence or presence of inhibition of cell proliferation. Interference with cell-cycle control may underly the modification by exogenous lactate of radiosensitivity and postirradiation repair capacity in mammalian cells.

Putative non-Mendelian transmission of retinoblastoma in males: a phenotypic segregation analysis of 150 pedigrees.

In a previous genotypic study of eight families, we described paternal segregation distortion favoring the transmission of mutant alleles at the retinoblastoma gene locus (RB1). In the current study, we reviewed all published retinoblastoma pedigrees with defined ascertainment (n = 150), to determine whether the phenotypic segregation frequency at the RB1 locus is in general influenced by the sex of the transmitting parent. Segregation analysis under complete ascertainment revealed that 49.1% of the offspring of male transmitters were affected, while 44.3% of the offspring of female transmitters were affected. While this difference is not statistically significant, it is consistent with the previous findings. No significant sex distortion could be detected among the progeny of carrier fathers and mothers. In order to quantify the transmission ratio more precisely further prospective molecular genetic analysis is warranted. We propose a biological mechanism to account for a putative segregation distortion, namely that genetic recombination creates clones of spermatogonia that are homozygous for the mutant RB1 allele leading to a non-Mendelian ratio of sperm. This model can be experimentally tested using amplification of DNA from single sperm cells.

Turcot's syndrome of glioma and polyposis occurs in the absence of germ line mutations of exons 5 to 9 of the p53 gene.

The term "Turcot's syndrome" has been used to describe approximatively 55 patients with an association of colonic polyposis and primary neuroepithelial tumors of the central nervous system. The p53 tumor suppressor gene is a possible candidate underlying the syndrome because (a) mutations in the p53 gene are ubiquitous in human cancer, including colon carcinoma and gliomas, and (b) somatic or germ line mutations of the p53 tumor suppressor gene cause the Li-Fraumeni syndrome, which is characterized by the association of breast and soft tissue tumors. We determined the DNA sequence of the conserved regions of the p53 gene (exons 5 to 9) in the tumor tissues and lymphocytes of two patients with glioma-polyposis and found that mutations did occur as independent tumor-specific alterations but did not involve the germ line of these patients, suggesting that p53 may play a role in progression but not initiation of the disease.

Radiosensitizing and repair-inhibiting properties of dipyridamole.

Radioresistance and postirradiation repair of potentially lethal damage (PLD repair) are important factors underlying failure to control local disease in cancer. Dipyridamole (DP) is known as a modifier of the action of cytotoxic drugs. We therefore investigated DP as a potential radiosensitizer and inhibitor of PLD repair in X-irradiated Chinese hamster ovary (CHO) cells in vitro. Exposure to the drug alone resulted in a slight reduction of the clonogenic capacity of the cells. Preincubation for 18 h with 10 and 20 microM DP in cells subcultured at low density, led to a significant radiosensitization. In confluent density-inhibited cultures, preincubation alone as well as pre- and postincubation with 20 microM DP resulted in a significant inhibition of PLD repair. Dipyridamole and related compounds may thus be useful tools for modifying and investigating the response of mammalian cells to radiation.

Detection of aneuploid subpopulations in colon cancer biopsies by cultivation in vitro prior to flow cytometric analysis.

Flow cytometry offers a relatively simple method to determine the DNA content of colorectal cancers. However, the technique can not discover minor changes in karyotype which may characterize near-diploid tumors, nor will it detect very small populations of aneuploid cells. In an attempt to improve the detection of such cells, we incubated biopsy material prior to analysis. This method revealed an aneuploid subpopulation in one of two biopsies studied. This simple protocol may ultimately lead to a more accurate assessment of the ploidy in colon cancer.

[Hereditary colorectal cancer: observations of a family study]. / Le cancer colo-rectal héréditaire: à propos d'une observation familiale.

Described in Switzerland in the early '60, the major features of hereditary non-polyposis colon cancer syndrome (HNPCCS) were established 20 years ago by H. T. Lynch. HNPCCS accounts for at least 60% of the colon cancer etiology. Cancer family syndrome is defined by the presence of extracolonic primary tumors in addition to colon cancer. Both syndromes are transmitted by an autosomic dominant pattern. None of the known biomarkers are specific and/or sensitive enough to rely on their predictive values of patient's risks. A typical Swiss family was investigated on the basis of the cancer-prone family history. 21% of the family members observed over 5 generations presented one or more (30% of the cases) colo-rectal neoplasms at the age of 50. 55% of the tumors were right sided. Histologically, half of the tumors were mucinous. 30% of metachronous cancer appeared within 10 years. Polyps (1-3) and flat adenomas were associated to the lesion in 57%. Extra-colonic tumors appeared in 18% of family members and in half of the colon cancer patients. The sites of these tumors were the urinary tract, ovary, small bowel, breast and stomach. Two fibroblast strains of affected individuals were established. No increased tetraploidy was noted. Preliminary results suggest that this two strains are rather sensitive to ionising radiation. Often neglected, family history of colon cancer remains the major diagnostic and decision-making tool of a such syndrome. It will necessitate special treatment of affected subjects and early screening of the relatives.(ABSTRACT TRUNCATED AT 250 WORDS)

Paternal selection favoring mutant alleles of the retinoblastoma susceptibility gene.

Penetrance and segregation rates of mutant Rb-1 alleles were assessed in all 51 members of eight kindreds with hereditary retinoblastoma by concomitant ophthalmologic examination and determination of seven intragenic restriction fragment length polymorphisms (RFLPs). Penetrance was in the range reported in the literature except for one family in which it was only 42.8%. However, the odds of transmitting a mutant Rb-1 allele from one generation to the next were 25:9 in this population, much above the Mendelian 1:1 ratio (P less than 0.025). This preferential transmission was discovered through the use of molecular information. Further analysis revealed that this distortion was due to preferential inheritance among children of male carriers (18:4, P less than 0.005). No difference from a 1:1 segregation ratio could be detected among the children of female carriers (7:5). These findings were consistent with a review of relevant data in the literature.

[Loss of ganglion cells in the retina secondary to vincristine therapy]. / Perte des cellules ganglionnaires de la rétine secondaire à la prise de vincristine.

We report the case of a 25-year-old black female from Zaire with AIDS diagnosed 2 years earlier. Nine months before her death, she was treated for a disseminated Kaposi sarcoma with vincristin, adryamycin and bleomycin. At that time, visual acuity was normal and ophthalmologic examination was unremarkable except for the presence of bilateral Drusen and a cotton wool spot OS. Three months after the onset of chemotherapy, the patient complained of progressive visual field constriction, which progressed to blindness within a 4 month period. Five months after the onset of the tri-therapy a bilateral CMV retinitis developed, which was successfully treated by intravitreous injections of ganciclovir. This therapy was stopped as soon as blindness was established, with subsequent massive bilateral recurrence of the CMV retinitis. Histologic examination showed complete atrophy of the retinal ganglion cells and areas of CMV retinitis. The optic nerve was demyelinated and exhibited astrocytic gliosis. Immunohistochemistry confirmed the presence of CMV in infected retina and revealed the absence in the optic nerve of the class III beta-tubulin isotype and of the 200 kd neurofilament subunit. In contrast, oculomotor nerves appeared intact. The presence of HIV in the eye and in the optic nerve was excluded using PCR technique. The retinal ganglion cell loss and optic nerve atrophy appeared to be purely degenerative in nature, since there was no evidence of vascular occlusion, inflammation or retrobulbar compressive process. We therefore conclude that blindness was caused by vincristine therapy. The patient actually received 22 mg of vincristin intravenously in 11 courses over 7 months, although discontinuation was recommended by us after 5 months.(ABSTRACT TRUNCATED AT 250 WORDS)

A linear-quadratic model of cell survival considering both sublethal and potentially lethal radiation damage.

We assessed the dose-dependence of repair of potentially lethal damage in Chinese hamster ovary cells x-irradiated in vitro. The recovery ratio (RR) by which survival (SF) of the irradiated cells was enhanced increased exponentially with a linear and a quadratic component, namely xi and psi: RR = e xi D + psi D2. Survival of irradiated cells can thus be expressed by a combined linear-quadratic model considering four variable, namely alpha and beta for the capacity of the cells to accumulate sublethal damage, and xi and psi for their capacity to repair potentially lethal damage: SF = e(xi - alpha)D + (psi - beta)D2.

[Lausanne study of retinoblastoma, 1986-90: deletion of esterase D locus in a collective of 128 patients]. / Consultation Lausannoise du rétinoblastome, 1986-1990: déletions au locus de l'estérase D dans un collectif de 128 patients.

Activity and phenotype of red blood cell esterase D were systematically determined in a population of 128 retinoblastoma patients from 99 families and compared to 158 controls, in order to detect a chromosome 13q14 deletion. Among these patients 12 were healthy carriers and 116 affected carriers of a mutant allele of the retinoblastoma susceptibility gene (110 retinoblastoma, 5 retinoma, 1 phtisis bulbi). 4 patients were found to have decreased ESD levels in connection with 13q14 deletion which was confirmed by chromosome analysis. The data presented here suggest that ESD quantification has a high specificity and sensitivity for the detection of homogenous chromosome 13 deletions in retinoblastoma patients.