Diffuse intra-abdominal sarcomatosis in myxoid pleomorphic liposarcoma

We present a case of an extremely rare type of soft-tissue sarcoma with an atypical clinical presentation. The patient, a female in her 20s with Li Fraumeni syndrome, had prior surgery for a large intra-abdominal tumour that was given the diagnosis of malignant myxoid spindle cell neoplasm. Her recurrence manifested as diffuse intra-abdominal sarcomatosis for which she ultimately underwent subtotal debulking with palliative intent. Final pathology rendered the diagnosis of myxoid pleomorphic liposarcoma, a newly described entity, distinct from the more common liposarcoma subtypes. The optimal treatment for this typically aggressive disease is currently unknown; until that is better defined, management should be carried out by sarcoma specialists.

Malignant Perivascular Epithelioid Cell Tumor (PEComa) of the Uterus as Part of the Hereditary Cancer Syndrome: A Case Diagnosed with Multiple Malignancies

A perivascular epithelioid cell tumor (PEComa) is an uncommon mesenchymal tumor composed of perivascular epithelioid cells. These tumor cells show variable immunoreactivity for both melanocytic and myogenic markers. Occurrence of PEComa has been reported at various anatomical sites, including the gynecological tract, uterus being the most common. Although most patients have sporadic PEComas, a subset may be associated with the inactivation of TSC1 or TSC2 genes and the occurrence of TFE3 gene fusions. However, a relationship between PEComas and other tumors is rare. We report a 41-year-old female patient with malignant PEComa who was admitted to the hospital with a complaint of vaginal bleeding. Because she had previously been diagnosed with colorectal and breast carcinomas at an early age, we performed a comprehensive genetic analysis to identify molecular alterations present in her background that unveiled multiple malignancy predispositions. Next-generation sequencing (NGS) analysis revealed two heterozygous germline pathogenic variants in the ATM and TP53 genes and a heterozygous variant of unknown significance (VUS) in the BRCA2 gene. The patient was diagnosed with the Li-Fraumeni Syndrome owing to the medical and family history and also the presentation of a pathogenic mutation of the TP53 gene. There are very few case reports in the literature describing PEComa in the Li-Fraumeni syndrome, and this is the first report of a uterine PEComa in a patient with Li-Fraumeni syndrome.

Application of the International Classification of Functioning principles to guide rehabilitation following hemipelvectomy in an adolescent with Li-Fraumeni syndrome: A case report

This case report details the complex case of an adolescent patient with chondroblastic osteosarcoma in the setting of Li-Fraumeni syndrome, leading to hemipelvectomy and post-operative complications. International Classification of Functioning principles were used as a roadmap for optimization of functional restoration and transition of care coordination.

A mouse model for Li-Fraumeni-Like Syndrome with cardiac angiosarcomas associated to POT1 mutations

The shelterin protein POT1 has been found mutated in many different familial and sporadic cancers, however, no mouse models to understand the pathobiology of these mutations have been developed so far. To address the molecular mechanisms underlying the tumorigenic effects of POT1 mutant proteins in humans, we have generated a mouse model for the human POT1^R117C mutation found in Li-Fraumeni-Like families with cases of cardiac angiosarcoma by introducing this mutation in the Pot1a endogenous locus, knock-in for Pot1a^R117C. We find here that both mouse embryonic fibroblasts (MEFs) and tissues from Pot1a^+/ki mice show longer telomeres than wild-type controls. Longer telomeres in Pot1a^+/ki MEFs are dependent on telomerase activity as they are not found in double mutant Pot1a^+/kiTert^-/- telomerase-deficient MEFs. By using complementation assays we further show that POT1a pR117C exerts dominant-negative effects at telomeres. As in human Li-Fraumeni patients, heterozygous Pot1a^+/ki mice spontaneously develop a high incidence of angiosarcomas, including cardiac angiosarcomas, and this is associated to the presence of abnormally long telomeres in endothelial cells as well as in the tumors. The Pot1a^+/R117C mouse model constitutes a useful tool to understand human cancers initiated by POT1 mutations.

We have generated a mouse model for the human POT1^R117C mutation found in Li-Fraumeni-Like (LFL) families with cases of cardiac angiosarcoma by introducing this mutation in the Pot1a endogenous locus, knock-in for Pot1a^R117C. The Pot1a^+/ki mice show longer telomeres than wild-type controls. Longer telomeres in mutant mice are dependent on telomerase activity as they are not found in a telomerase deficient background. As in human Li-Fraumeni patients, heterozygous Pot1a^+/ki mice spontaneously develop a high incidence of angiosarcomas, including cardiac angiosarcomas, and this is associated to the presence of abnormally long telomeres in endothelial cells as well as in the tumors. The ki-Pot1a^R117C mouse constitutes a potential pre-clinical mouse model for LFL syndrome presenting with high angiosarcoma incidence that could provide in the future a very useful tool for the study of treatments for these tumors.

[Imaging of tumor predisposition syndromes]

CLINICAL ISSUE

Tumor predisposition syndromes (TPS) are a heterogeneous group of genetic cancers. About 10% of the approximately 2200 malignancies in the childhood in Germany develop due to an inherited disposition, whereby TPS may be underdiagnosed. The focus of this review is set on imaging of Li-Fraumeni syndrome, neurofibromatoses, tuberous sclerosis, overgrowth, and neuroendocrine syndromes.

STANDARD RADIOLOGICAL METHODS

In order to detect tumors at an early stage, screening at specific time intervals for each TPS are required. Ultrasonography and magnetic resonance imaging (MRI), especially whole-body MRI, are particularly important imaging modalities.

METHODOLOGICAL INNOVATIONS

Innovative MRI techniques can increase image quality and patient comfort. MRI acquisition time can be significantly reduced through optimized acceleration factors, motion robust radial sequences and joint acquisition and readout of multiple slices during excitation. Thus, shorter MRI examinations can be performed in younger children without anesthesia.

PRACTICAL RECOMMENDATION

Regular screening with ultrasound and MRI can reduce the morbidity and mortality of the patients affected with TPS.

Modeling of osteosarcoma with induced pluripotent stem cells

Osteosarcoma is the most common type of bone cancer. Osteosarcoma is commonly associated with TP53 inactivation (around 95% of cases) and RB1 inactivation (around 28% of cases). With the discovery of reprogramming factors to induce pluripotency even in terminally differentiated cells, induced pluripotent stem cells (iPSCs) have emerged as a promising disease model. iPSC-based disease modeling uniquely recapitulates disease phenotypes and can support discoveries into disease etiology and is used extensively today to study a variety of diseases, including cancers. This paper focuses on iPSC-based modeling of Li-Fraumeni syndrome (LFS), an autosomal dominant disorder commonly associated with TP53 mutation and high osteosarcoma incidence. As iPSCs are increasingly utilized as a platform for cancer modeling, the experimental approaches that we discuss here may serve as a guide for future studies.

[Li-Fraumeni Syndrome-Current Status and Prospects in Clinical Practice]

Li-Fraumeni syndrome(LFS)is a cancer predisposing disorder with early-onset cancers in diverse tissues of origin, caused by germline TP53 mutation. In LFS, 5 core cancers are known: breast cancer, soft tissue sarcoma, osteosarcoma, brain tumor, adrenocortical cancer. Surveillance for LFS must be lifetime long and multitargeted since the patients are susceptible to various cancers from infant to middle-aged and older. Recent investigations have revealed germline TP53 mutations can increase the riskfor radio-induced tumorigenesis and will affect patient's prognosis and treatment in several cancers. The surveillance protocol has developed in Canada and several prospective studies based on the Canadian's one are currently being carried out. We are aware that the surveillance protocol suitable for the current status in Japan is urgently needed to provide the appropriate medical care for LFS patients.

[Diagnosis, surveillance, and management of familial leukemia]

Recently, the modern technique of comprehensive genomic analysis has identified both somatic mutations originating from tumor cells and germline mutations as causative genes of inherited familial leukemias among which Fanconi anemia and Li-Fraumeni syndrome are well known. Pathogenic germline mutations occur in various pathways, affecting DNA repair, ribosome biogenesis, telomere biology, hematopoietic transcription factors, tumor suppressors, neutrophil development, and other critical cellular processes. The clinical manifestations of germline mutations present a wide phenotypic spectrum of patients displaying congenital anomalies, early-onset myelodysplastic syndrome, or no medical problems until the developing leukemia. The use of genetic tests to identify these affected persons will significantly benefit cancer surveillance and subsequent therapeutic interventions. Although familial leukemia treatment usually focuses on children, it is important for clinicians to recognize that familial leukemias can occur at any age, even among older adults. Genetic counseling after diagnosis is essential, and an immediate referral to experts in each disease is recommended.

[TP53 mutations and hematological malignancies]

TP53 is a tumor-suppressor gene, and it is the most commonly mutated somatic gene in human cancer. Germline TP53 mutations correlate with a hereditary predisposition to cancer. Comprehensive genetic analysis revealed the role of germline and somatic TP53 gene mutations in hematological malignancies. TP53 mutations affect the prognosis and therapeutic decision-making. Hence, genetic screening and tumor surveillance, including family members, should be performed when a germline TP53 mutation is detected in a patient.

The Features of Colorectal Tumors in a Patient with Li-Fraumeni Syndrome

A young woman with Li-Fraumeni syndrome (LFS) was referred to our hospital. On examination, multiple flat neoplasms were detected in addition to semi-pedunculated polyps. Restorative proctocolectomy was performed; one submucosal invasive cancer, two mucosal cancers, and several adenomas with high-grade dysplasia were detected. On immunohistochemical staining with p53, every part of all neoplasms, even the small adenomas, showed strong positive staining. Multiple flat neoplasms may be characteristic of patients with LFS and may have a much higher risk of rapid progression to invasive carcinomas than sporadic neoplasms. Thus, careful and frequent colonoscopy surveillance may be needed for patients with LFS.

p53 protein regulates Hsp90 ATPase activity and thereby Wnt signaling by modulating Aha1 expression

The p53 tumor suppressor gene encodes a homotetrameric transcription factor which is activated in response to a variety of cellular stressors, including DNA damage and oncogene activation. p53 mutations occur in >50% of human cancers. Although p53 has been shown to regulate Wnt signaling, the underlying mechanisms are not well understood. Here we show that silencing p53 in colon cancer cells led to increased expression of Aha1, a co-chaperone of Hsp90. Heat shock factor-1 was important for mediating the changes in Aha1 levels. Increased Aha1 levels were associated with enhanced interactions with Hsp90, resulting in increased Hsp90 ATPase activity. Moreover, increased Hsp90 ATPase activity resulted in increased phosphorylation of Akt and glycogen synthase kinase-3β (GSK3β), leading to enhanced expression of Wnt target genes. Significantly, levels of Aha1, Hsp90 ATPase activity, Akt, and GSK3β phosphorylation and expression of Wnt target genes were increased in the colons of p53-null as compared with p53 wild type mice. Using p53 heterozygous mutant epithelial cells from Li-Fraumeni syndrome patients, we show that a monoallelic mutation of p53 was sufficient to activate the Aha1/Hsp90 ATPase axis leading to stimulation of Wnt signaling and increased expression of Wnt target genes. Pharmacologic intervention with CP-31398, a p53 rescue agent, inhibited recruitment of Aha1 to Hsp90 and suppressed Wnt-mediated gene expression in colon cancer cells. Taken together, this study provides new insights into the mechanism by which p53 regulates Wnt signaling and raises the intriguing possibility that p53 status may affect the efficacy of anticancer therapies targeting Hsp90 ATPase.

Radiation-sensitive genetically susceptible pediatric sub-populations

Major advances in pediatric cancer treatment have resulted in substantial improvements in survival. However, concern has emerged about the late effects of cancer therapy, especially radiation-related second cancers. Studies of childhood cancer patients with inherited cancer syndromes can provide insights into the interaction between radiation and genetic susceptibility to multiple cancers. Children with retinoblastoma (Rb), neurofibromatosis type 1 (NF1), Li-Fraumeni syndrome (LFS), and nevoid basal cell carcinoma syndrome (NBCCS) are at substantial risk of developing radiation-related second and third cancers. A radiation dose-response for bone and soft-tissue sarcomas has been observed in hereditary Rb patients, with many of these cancers occurring in the radiation field. Studies of NF1 patients irradiated for optic pathway gliomas have reported increased risks of developing another cancer associated with radiotherapy. High relative risks for second and third cancers were observed for a cohort of 200 LFS family members, especially children, possibly related to radiotherapy. Children with NBCCS are very sensitive to radiation and develop multiple basal cell cancers in irradiated areas. Clinicians following these patients should be aware of their increased genetic susceptibility to multiple primary malignancies enhanced by sensitivity to ionizing radiation.

Adenocarcinoma of the colon developing on the basis of Crohn's disease in childhood

Colorectal carcinoma rarely affects children and has a dismal prognosis with 5-year survival rates as low as 2.5%-7% despite apparently radical surgery. Here we report the case of an adenocarcinoma of the sigmoid colon in a 15-year-old girl preceded by uncertain abdominal complaints of 5 years' duration. Pathological work-up revealed a tumour with lymph node metastases (pT3NI). Immunohistochemical evidence of p53 overexpression by the tumour cells raised the suspicion of an underlying Li-Fraumeni syndrome. In addition, there were aphthoid ulceration, fissuration of the non-tumorous mucosa, along with a mixed transmural infiltrate composed of macrophages, eosinophils, and non-typical giant cells, which were compatible with simultaneous Crohn's disease. Anamnestic data concerning the occurrence of idiopathic inflammatory bowel disease or colorectal carcinoma in the patient's relatives were non-contributory. The present results suggest a possible relationship between Crohn's disease and colon cancer due to the defective p53 gene product.

Effects of chemopreventive and antitelomerase agents on the spontaneous immortalization of breast epithelial cells

BACKGROUND

Activation of telomerase is an early event in the development of breast and other cancers that may lead to cell immortalization, a critical and rate-limiting step in cancer progression. Breast epithelial cells from women with Li-Fraumeni syndrome (LFS) immortalize spontaneously and reproducibly in culture. We, therefore, tested whether immortalization of these cells could be prevented by treating them with chemopreventive agents and by inhibiting telomerase activity.

METHODS

Noncancerous, preimmortal breast epithelial cells derived from a patient with LFS were treated for 3 months with nontoxic concentrations of the chemopreventive agents oltipraz, difluoromethylornithine, tamoxifen, and retinoic acid or with two different telomerase inhibitors. The frequency of spontaneous immortalization of LFS-derived cells was estimated by an approach based on fluctuation analyses. Statistical analyses were two-sided.

RESULTS

The frequency of spontaneous immortalization events of LFS-derived breast epithelial cells was reduced by long-term treatment with retinoic acid (P<0.001) or tamoxifen (P<0.05) compared with solvent-treated cells. The frequency of immortalization was also reduced by treating LFS-derived cells with an antitelomerase antisense oligonucleotide (P<0.001) or by inducing the cells to express a dominant negative mutant of telomerase (P<0.025) compared with cells treated with a control oligonucleotide or with empty vector, respectively.

CONCLUSIONS

Treatment of preimmortal LFS breast epithelial cells with chemopreventive and antitelomerase agents decreased the frequency of spontaneous immortalization in vitro. These studies validate the application of a new cell culture model system to screen the effects of novel chemopreventive agents by use of cell immortalization as an end point. The results also suggest that the telomerase ribonucleoprotein complex may be an important molecular target for breast cancer prevention.

The role of the p53 tumor suppressor in the response of human cells to photofrin-mediated photodynamic therapy

Although there is evidence that the p53 tumor suppressor plays a role in the response of some human cells to chemotherapy and radiation therapy, its role in the response of human cells to photodynamic therapy (PDT) is less clear. In order to examine the role of p53 in cellular sensitivity to PDT, we have examined the clonogenic survival of normal human fibroblasts that express wild-type p53 and immortalized Li-Fraumeni syndrome (LFS) cells that express only mutant p53, following Photofrin-mediated PDT. The LFS cells were found to be more resistant to PDT compared to normal human fibroblasts. The D37 (LFS cells)/D37 (normal human fibroblasts) was 2.8 +/- 0.3 for seven independent experiments. Although the uptake of Photofrin per cell was 1.6 +/- 0.1-fold greater in normal human fibroblast cells compared to that in LFS cells over the range of Photofrin concentrations employed, PDT treatment at equivalent cellular Photofrin levels also demonstrated an increased resistance for LFS cells compared to normal human fibroblasts. Furthermore, adenovirus-mediated transfer and expression of wild-type p53 in LFS cells resulted in an increased sensitivity to PDT but no change in the uptake of Photofrin per cell. These results suggest a role for p53 in the response of human cells to PDT. Although normal human fibroblasts displayed increased levels of p53 following PDT, we did not detect apoptosis or any marked alteration in the cell cycle of GM38 cells, despite a marked loss of cell viability. In contrast, LFS cells exhibited a prolonged accumulation of cells in G2 phase and underwent apoptosis following PDT at equivalent Photofrin levels. The number of apoptotic LFS cells increased with time after PDT and correlated with the loss of cell viability. A p53-independent induction of apoptosis appears to be an important mechanism contributing to loss of clonogenic survival after PDT in LFS cells, whereas the induction of apoptosis does not appear to be an important mechanism leading to loss of cell survival in the more sensitive normal human fibroblasts following PDT at equivalent cellular Photofrin levels.

Human cells compromised for p53 function exhibit defective global and transcription-coupled nucleotide excision repair, whereas cells compromised for pRb function are defective only in global repair

After exposure to DNA-damaging agents, the p53 tumor suppressor protects against neoplastic transformation by inducing growth arrest and apoptosis. A series of investigations has also demonstrated that, in UV-exposed cells, p53 regulates the removal of DNA photoproducts from the genome overall (global nucleotide excision repair), but does not participate in an overlapping pathway that removes damage specifically from the transcribed strand of active genes (transcription-coupled nucleotide excision repair). Here, the highly sensitive ligation-mediated PCR was employed to quantify, at nucleotide resolution, the repair of UVB-induced cyclobutane pyrimidine dimers (CPDs) in genetically p53-deficient Li-Fraumeni skin fibroblasts, as well as in human lung fibroblasts expressing the human papillomavirus (HPV) E6 oncoprotein that functionally inactivates p53. Lung fibroblasts expressing the HPV E7 gene product, which similarly inactivates the retinoblastoma tumor-suppressor protein (pRb), were also investigated. pRb acts downstream of p53 to mediate G(1) arrest, but has no demonstrated role in DNA repair. Relative to normal cells, HPV E6-expressing lung fibroblasts and Li-Fraumeni skin fibroblasts each manifested defective CPD repair along both the transcribed and nontranscribed strands of the p53 and/or c-jun loci. HPV E7-expressing lung fibroblasts also exhibited reduced CPD removal, but only along the nontranscribed strand. Our results provide striking evidence that transcription-coupled repair, in addition to global repair, are p53-dependent in UV-exposed human fibroblasts. Moreover, the observed DNA-repair defect in HPV E7-expressing cells reveals a function for this oncoprotein in HPV-mediated carcinogenesis, and may suggest a role for pRb in global nucleotide excision repair.

Primary embryonal rhabdomyosarcoma of the breast in an adolescent female: a case report

Rhabdomyosarcoma is the most common soft tissue sarcoma in children. Primary breast location has been reported rarely in the literature. Most rhabdomyosarcomas encountered in the breast more commonly are metastatic disease from some primary foci in another part of the body. This report addresses the case of an adolescent girl who had primary embryonal rhabdomyosarcoma of the breast with no evidence of local invasion or metastatic disease within the spectrum of Li-Fraumeni syndrome.

Aberrant p21WAF1-dependent growth arrest as the possible mechanism of abnormal resistance to ultraviolet light cytotoxicity in Li-Fraumeni syndrome fibroblast strains heterozygous for TP53 mutations

The purpose of this study is to better understand the roles of the p53 tumor suppressor protein and the product of the p53-regulated gene p21WAF1 in the response of diploid human dermal fibroblast cultures to 254 nm ultraviolet (UV) light. We report that Li-Fraumeni syndrome (LFS) fibroblast strains heterozygous for TP53 mutation at either codon 245 or 234 exhibit markedly reduced or no expression of p21WAF1 following UV irradiation, respectively. These strains also exhibit defective nucleotide excision repair and pronounced inhibition of RNA synthesis following UV exposure, both of which are molecular hallmarks of cells derived from patients with the UV-sensitive syndrome xeroderma pigmentosum. In sharp contrast to xeroderma pigmentosum cells, however, the repair-deficient LFS cells show abnormal resistance, rather than hypersensitivity, to the killing effect of UV light. We further demonstrate that exposure of normal human fibroblasts to biologically relevant fluences (< or = 15 J/m2) of UV does not induce apoptotic cell death, indicating that UV resistant phenotype displayed by LFS strains is not associated with deregulated apoptosis. In normal fibroblasts, such treatment results in a moderate ( threefold) up-regulation of p53 protein, induction of the p21WAF1 gene, and a senescence-like growth arrest. On the other hand, exposure to > or = 20 J/m2 UV results in a striking up-regulation of p53, inhibition of p21WAF1 expression, and activation of an apoptotic pathway. We conclude that: (i) p21WAF1-mediated senescence is the principal mode of cell death induced by < or = 15 J/m2 UV light in normal human fibroblasts; (ii) there is a threshold effect for p53-dependent apoptosis and that, in normal human cells, this threshold level is induced upon expsoure to 20 J/m2 UV; (iii) the p53 signaling pathway is malfunctional in the TP53 heterozygous LFS strains examined; and (iv) the enhanced resistance to UV-induced cell killing displayed by these LFS strains is a consequence of diminished growth arrest, which is presumably mediated by p21WAF1 and not abnormalities in an apoptotic pathway.

Independent induction of senescence by p16INK4a and p21CIP1 in spontaneously immortalized human fibroblasts

In this work, we address the question of whether replicative senescence can be induced in immortal nontumorigenic human fibroblasts. The immortal fibroblasts used in this study were derived from two Li-Fraumeni (LF) patients who carry in their germ line one wild-type and one mutant p53 allele. Both immortal lines have lost the wtp53 allele and express no detectable p16INK4a protein, although they carry the p16INK4a gene. In contrast to immortal human fibroblasts, senescent human fibroblasts have a low content of 5-methyl-cytosine in their DNA. This observation suggested the possibility that a demethylating agent could revert the immortal phenotype and induce replicative senescence in the immortal cell lines. Cells of the two LF lines were exposed to the demethylating agent 5-aza-2'-deoxycytidine. Within 6 days, all cells were growth arrested and showed the enlarged and flat morphology characteristic of senescent cells, an accumulation of lipofuscin granules and senescence-associated beta-galactosidase activity at pH6, both biomarkers for senescence. Immunoblots of 5-aza-2'-deoxycytidine-treated cells showed a greatly increased expression of p16INK4a protein but no detectable change in the expression of p21CIP1, a gene known to be strongly expressed in senescent normal human fibroblasts. In two other experimental series, cells of the two LF lines were infected with retroviral constructs encoding either p16INK4a or p21CIP1. Each of the transduced genes induced senescence without affecting the expression of the other endogenous gene. The results show that induction of senescence in immortal LF fibroblasts can occur by different pathways: (a) by demethylation-dependent pathways that induce the expression of p16INK4a; and (b) by demethylation-independent pathways involving the expression of p21CIP1. The induction of senescence by p16INK4a and p21CIP1 occurred equally in the two human immortal fibroblast lines, which differed in the length of their telomeres and the activity of their telomerase.

Control of angiogenesis in fibroblasts by p53 regulation of thrombospondin-1

As normal cells progress toward malignancy, they must switch to an angiogenic phenotype to attract the nourishing vasculature that they depend on for their growth. In cultured fibroblasts from Li-Fraumeni patients, this switch was found to coincide with loss of the wild-type allele of the p53 tumor suppressor gene and to be the result of reduced expression of thrombospondin-1 (TSP-1), a potent inhibitor of angiogenesis. Transfection assays revealed that p53 can stimulate the endogenous TSP-1 gene and positively regulate TSP-1 promoter sequences. These data indicate that, in fibroblasts, wild-type p53 inhibits angiogenesis through regulation of TSP-1 synthesis.