Carbon Ion Radiotherapy for sacral chordoma: a systematic review of the literature

The aim of the present study is to describe the clinical outcomes and the incidence of complications related to Carbon Ion Radiotherapy (CIRT) in the treatment of sacral chordoma. Through a systematic review of published investigations on CIRT, we collected the local control rates (LC), the overall survival rates (OS) and the post-CIRT adverse effects. Afterwards, we calculated their weighted average, to have a broader perspective. PubMed/Medline and Google Scholar databases were searched to identify studies on Carbon Ion Radiotherapy as a treatment for sacral chordoma. We used Medical Subject Heading (MeSh) terms and keywords. We based our systematic review on the PRISMA guidelines. No data limitations were applied in the search on Pubmed/ Medline database; data limitation (from 2000 to 2019) was applied in the search on Google Scholar. Six studies were included in our review. Local control proportions reported in individual studies ranged between 77% and 96% (95% confidence interval), with respect to a 5-years follow-up. Overall survival rates ranged from 52% to 86% (95% confidence interval), with respect to a 5-years follow-up. Adverse CIRT-related events involving bone occurred in 7% of patients. Neurological and skin toxicities affected 20% and 5% of patients, respectively. Nowadays the gold standard of treatment for sacral chordoma is the surgical resection with wide margins. Whenever adequate oncological margins could not be achieved or could be achieved only by sacrificing neurological structures with consequent functional impairment, CIRT is an effective alternative which has been demonstrated to reach optimal local control and overall survival rate. The caregiver, anyway, should be aware of the potential adverse events and complications related to this kind of treatment.

Percutaneous vertebroplasty and balloon kyphoplasty in the treatment of osteoporotic vertebral fractures: a prospective randomized comparison

PURPOSE

The purpose of this study is to compare the efficacy and safety of percutaneous vertebroplasty (PVP) and balloon kyphoplasty (BKP) in the treatment of osteoporotic vertebral compression fractures.

MATERIALS AND METHODS

Patients with osteoporotic vertebral body fractures (T4-L5) were randomized and not blinded to kyphoplasty (n = 69) or vertebroplasty (n = 70). The postoperative pain score (VAS) at 12 months was the primary end point. The radiographic results were evaluated in relation to the resolution of the fracture and the possible onset of further osteoporotic fractures during follow-up.

RESULTS

A total of one hundred and thirty-nine patients were eligible for randomization (n = 70 for PVP group and n = 69 for BKP), and twenty-six patients (twenty in the BKP group and six in the PVP group) were excluded. The mean average age of patients was 73 years, and 82% of the patients were females. VAS pain score was significantly reduced after surgery in both groups, and there were no significant differences between the two groups in postoperative VAS score. There was a significant reduction in kyphotic wedge angle and improvement of the sagittal index in both groups, but there was no significant difference between the two groups. There was a significant higher risk incidence of adjacent level fractures in the vertebroplasty group.

CONCLUSIONS

In terms of clinical outcomes, there were no differences between the two groups. Both showed a significant clinical improvement, vertebral body height restoration and reduction in the kyphotic angle. There was a significant higher risk of adjacent level fractures in the vertebroplasty group.

Isthmic spondylolisthesis and interspinous process device. Hype, hope, or contraindication?

OBJECTIVE

The aim of this study is to investigate, through the analysis of a case report and the literature review, indications and contraindications of Interspinous Process Device (IPD) in the surgical treatment of Lumbar Isthmic Spondylolisthesis (LIS).

PATIENTS AND METHODS

A 37-years-old male with L5-S1 grade 2 LIS, treated with IPD at another center, referred to us eight months later with a worsening of back and leg pain. A revision surgery was performed with IPD removal and a L5-S1 TLIF.

RESULTS

Clinical evaluation highlighted an improvement of pain, functionality, and quality of life scores at six months (VAS 4; ODI 30; EQ-5D 70) and twelve months follow-up (VAS 1; ODI 20; EQ-5D 90). CT scan was performed at six months and one-year follow-up to evaluate the fusion rate and stability of the implant.

CONCLUSIONS

Given the pathologic anatomy and the biomechanics of LIS, IPD is ineffective in preventing further vertebral body slippage resulting in segmental kyphosis, because of the lack of connection between the posterior arch and the vertebral body due to the isthmic lesion.

Medicine in the time of Carracci: the cases of Domenico Lanzoni and Giuseppe Rosaccio

During the 16th century and at the beginning of the 17th century the age-old competition between scholarly doctors and folk healers became more and more serious, creating a division between the two categories entrusted with treating population diseases. On one side there were the representatives who practiced medicine in an official capacity, and on the other, the "others", that is, the charlatans, the acrobats and female healers. Two representatives of these contrasting approaches of practicing medicine within the health profession during that historical period were two Italian doctors, Domenico Lanzoni and Giuseppe Rosaccio. Together, with their ties to the city of Bologna and the bolognese Carracci family of painters, they were able to describe in complete detail these two types of practices as medical sciences of the sixteenth and early seventeenth century.

Biomaterials as bone graft substitutes for spine surgery: from preclinical results to clinical study

Vertebral fusion is performed in order to stabilize the spine in the presence of degenerative, traumatic or oncological pathologies that alter its stability. The autologous bone, harvested from the patient’s iliac crest or from the lamina during surgery, is still considered the “gold standard” for spine fusion due to its osteogenic, osteoinductive and osteoconductive properties. However, several biological and synthetic bone substitutes have been introduced as alternatives for regenerating bone tissue. We have studied in particular the use of ceramic biomaterials prepared from hydroxypatite (HA), starting from in vitro analysis, through an in vivo study on ovine animal model and a post-market surveillance analysis, to finally design and perform a clinical study, which is ongoing in our Department. In the first step, HA-derived biomaterials were tested in vitro in the presence of bone marrow-derived human mesenchymal stem cells (hMSCs) and evaluated for their ability to activate precursor cells. In the second step, the biomimetic bone graft substitute SintLife® putty (MgHA) was evaluated in vivo. A posterolateral fusion procedure was applied on 18 sheep, where a fusion level was treated with MgHA, while the other level was treated with autologous bone. Microtomography and histological/histomorphometric analysis were performed six months of after surgery. In the third step, we reported the results of a post-market surveillance study conducted on 4 independent cohorts of patients (total 115 patients), in which HA-derived biomaterials were used as bone graft substitutes or extenders. Finally, a clinical study has been designed and approved by the Ethics Committee of our Institute and is currently ongoing. This study aims to evaluate the efficacy of the ceramic biomaterial SintLife® putty for bone replacement in patients treated by posterolateral fusion for degenerative spine disorders. HA biomaterials were effective in promoting the in vitro growth of hMSCs and their osteogenic differentiation. In the animal model, SintLife® putty has been effective in generating neo-formed bone tissue with morphological and structural features similar to those of the pre-existing bone. The post-market surveillance analysis has not reported any intra-operative nor early or late post-operative adverse events. Seven patients are currently recruited for the clinical trial designed to evaluate Sintlife efficacy for spine fusion (FU range: 1-7 months). No adverse events have been recorded. The first CT analysis performed at 6 months FU showed a good spine fusion. The study is ongoing. Our results, obtained from in vitro, preclinical and clinical studies, suggest that biomaterials derived from hydroxyapatite could be a valid alternative to autologous bone graft for vertebral fusion. This would potentially avoid or reduce the need of autologous bone harvesting and therefore, the risk of drawback-related side effects.

A post-market surveillance analysis of the safety of hydroxyapatite-derived products as bone graft extenders or substitutes for spine fusion

OBJECTIVE

Iliac crest bone graft (ICBG) is considered the gold standard for spine surgical procedures to achieve a successful fusion, because of its known osteoinductive and osteoconductive properties. Considering its autogenous origin, the use of ICBG has not been associated to an increase of intraoperative or postoperative complications directly related to the surgery. However, complications related to the harvesting procedure and to the donor site morbidity have been largely reported in the literature, favoring the development of a wide range of alternative products to be used as bone graft extenders or substitutes for spine fusion. The family of ceramic-based bone grafts has been widely used and studied during the last years for spine surgical procedures in order to reduce the need for iliac crest bone grafting and the consequent morbidity associated to the harvesting procedures.

PATIENTS AND METHODS

We report here the results of a post-market surveillance analysis performed on four independent cohorts of patients (115 patients) to evaluate the safety of three different formulations of hydroxyapatite-derived products used as bone graft extenders/substitutes for lumbar arthrodesis.

RESULTS

No intraoperative or post-operative complications related to the use of hydroxyapatite-derived products were detected, during medium and long follow up period (minimum 12 months-maximum 5 years).

CONCLUSIONS

This post-market surveillance analysis evidenced the safety of ceramic products as bone graft extenders or substitutes for spine fusion. Moreover, the evidence of the safety of hydroxyapatite-derived products allows to perform clinical studies aimed at evaluating the fusion rates and the clinical outcomes of these materials as bone graft extenders/substitutes, in order to support their use as an alternative to ICBG for spine fusion.

Polyetheretherketone (PEEK) rods: short-term results in lumbar spine degenerative disease

Pedicle screw and rod instrumentation has become the preferred technique for performing stabilization and fusion in the surgical treatment of lumbar spine degenerative disease. Rigid fixation leads to high fusion rates but may also contribute to stress shielding and adjacent segment degeneration. Thus, the use of semirigid rods made of polyetheretherketone (PEEK) has been proposed. Although the PEEK rods biomechanical properties, such as anterior load sharing properties, have been shown, there are few clinical studies evaluating their application in the lumbar spine surgical treatment. This study examined a retrospective cohort of patients who underwent posterior lumbar fusion for degenerative disease using PEEK rods, in order to evaluate the clinical and radiological outcomes and the incidence of complications.

Is lumbar drainage of postoperative cerebrospinal fluid fistula after spine surgery effective?

AIM

This study is a retrospective consecutive case series analysis of 198 patients who underwent spine surgery between 2009 and 2010. The aim of this paper was to assess the efficacy and safeness of bed rest and lumbar drainage in treating postoperative CSF fistula. Postoperative cerebrospinal fluid (CSF) fistula is a well-known complication in spine surgery which lead to a significant change in length of hospitalization and possible postoperative complications. Management of CSF leaks has changed little over the past 20 years with no golden standard advocated from literature.

METHODS

Postoperative CSF fistulas were described in 16 of 198 patients (8%) who underwent spine surgery between 2009 and 2010. The choice of the therapeutic strategy was based on the clinical condition of the patients, taking into account the possibility to maintain the prone position continuously and the risk of morbidity due to prolonged bed rest. Six patients were treated conservatively (position prone for three weeks), ten patients were treated by positioning an external CSF lumbar drainage for ten days. The mean follow-up period was ten months.

RESULTS

All patients healed their wound properly and no adverse events were recorded. Patients treated conservatively were cured in a mean period of 30 days, while patients treated with CSF drainage were cured in a mean period of 10 days.

CONCLUSION

Lumbar drainage seems to be effective and safe both in preventing CSF fistula in cases of large dural tears and debilitated/irradiated patients and in treating CSF leaks.

Surgical treatment of thoraco-lumbar fractures in sickle cell disease: a case report

Sickle cell disease (or drepanocytosis) is a hemoglobinopathy characterized by an increase in viscosity and adhesivity of the typically sickle-shaped erythrocytes. The pathological osteo-articular involvement in the course of drepanocytosis is secondary to the avascular necrosis of the bone marrow, caused by vaso-occlusive episodes in the microcirculation during acute painful crises. Osteoporosis and extramedullary hematopoiesis are also consequences of the disease. The involvement of the spine is common, with clinical features ranging from simple changes in spinal morphology ("fish-mouth" appearance) up to vertebral bodies fractures with kyphotic deformity. In the presence of vertebral fracture, treatment options listed in the literature are conservative (rest, symptomatic therapy, orthosis), because of the high incidence of intra- and perioperative complications (acute respiratory syndrome, vaso-occlusive crisis…), in addition to the increased rate of implant failure. We report here a case of a young man affected by multiple pathological symptomatic vertebral fractures at the thoraco-lumbar junction, secondary to a well controlled but severe form of sickle cell disease. We decided to treat the patient surgically because of a worsening and potentially invalidating kyphosis deformity. We describe the surgical procedure and the management of a later complication consisting in the collapse of the osteoporotic vertebra below the instrumentation that required a surgical revision. Although a conservative approach is most frequently indicated, we believe that the surgical option should be considered when a clinical worsening occurs in a young patient with otherwise well-controlled disease.

Human mesenchymal stem cells and biomaterials interaction: a promising synergy to improve spine fusion

PURPOSE

Spine fusion is the gold standard treatment in degenerative and traumatic spine diseases. The bone regenerative medicine needs (i) in vitro functionally active osteoblasts, and/or (ii) the in vivo induction of the tissue. The bone tissue engineering seems to be a very promising approach for the effectiveness of orthopedic surgical procedures, clinical applications are often hampered by the limited availability of bone allograft or substitutes. New biomaterials have been recently developed for the orthopedic applications. The main characteristics of these scaffolds are the ability to induce the bone tissue formation by generating an appropriate environment for (i) the cell growth and (ii) recruiting precursor bone cells for the proliferation and differentiation. A new prototype of biomaterials known as "bioceramics" may own these features. Bioceramics are bone substitutes mainly composed of calcium and phosphate complex salt derivatives.

METHODS

In this study, the characteristics bioceramics bone substitutes have been tested with human mesenchymal stem cells obtained from the bone marrow of adult orthopedic patients.

RESULTS

These cellular models can be employed to characterize in vitro the behavior of different biomaterials, which are used as bone void fillers or three-dimensional scaffolds.

CONCLUSIONS

Human mesenchymal stem cells in combination with biomaterials seem to be good alternative to the autologous or allogenic bone fusion in spine surgery. The cellular model used in our study is a useful tool for investigating cytocompatibility and biological features of HA-derived scaffolds.

Osteoporotic vertebral fractures: a disabling and expensive disease of our century. A minimally invasive surgical technique to reduce the pain, the hospitalization, and restore the function

BACKGROUND AND OBJECTIVES

Minimally invasive spine surgery has gained a great consent in the treatment of vertebral osteoporotic fractures. We perform a retrospective clinical and radiographic review on 32 consecutive patients (22 female and 10 male) surgically treated for a thoracolumbar osteoporotic fracture (type A) by a minimally invasive system. By this study, we propose to determine the safety and efficacy of an expandable, percutaneous, minimally invasive technique to reduce the disability caused by vertebral osteoporotic fractures.

MATERIAL AND METHODS

We retrospectively reviewed 32 patients who were operated on between 2003 and 2004 by means of an innovative technique which employs an expandable system inserted by a minimally invasive approach into the vertebral body. Average age at surgery was 64.8 years (range, 27-82). All patients were mobilized in first post-operative day with no external immobilization and discharged from the Hospital in the second post-operative day.

RESULTS AND CONCLUSIONS

This innovative technique which employs an expandable system inserted by a minimally-invasive approach into the vertebral body permits to obtain a double mechanical support for the vertebral plate, to partially reduce the fracture, to mobilize the patient immediately, reducing disability and costs related to the vertebral osteoporotic fractures.

RNA interference as a key to knockdown overexpressed cyclooxygenase-2 gene in tumour cells

Silencing those genes that are overexpressed in cancer and contribute to the survival and progression of tumour cells is the aim of several researches. Cyclooxygenase-2 (COX-2) is one of the most intensively studied genes since it is overexpressed in most tumours, mainly in colon cancer. The use of specific COX-2 inhibitors to treat colon cancer has generated great enthusiasm. Yet, the side effects of some inhibitors emerging during long-term treatment have caused much concern. Genes silencing by RNA interference (RNAi) has led to new directions in the field of experimental oncology. In this study, we detected sequences directed against COX-2 mRNA, that potently downregulate COX-2 gene expression and inhibit phorbol 12-myristate 13-acetate-induced angiogenesis in vitro in a specific, nontoxic manner. Moreover, we found that the insertion of a specific cassette carrying anti-COX-2 short hairpin RNA sequence into a viral vector (pSUPER.retro) greatly increased silencing potency in a colon cancer cell line (HT29) without activating any interferon response. Phenotypically, COX-2 deficient HT29 cells showed a significant impairment of their in vitro malignant behaviour. Thus, the retroviral approach enhancing COX-2 knockdown, mediated by RNAi, proved to be an useful tool to better understand the role of COX-2 in colon cancer. Furthermore, the higher infection efficiency we observed in tumour cells, if compared to normal endothelial cells, may disclose the possibility to specifically treat tumour cells without impairing endothelial COX-2 activity.

Colocalization prostacyclin (PGI2) synthase--caveolin-1 in endothelial cells and new roles for PGI2 in angiogenesis

In vascular cells, prostacyclin (PGI2) synthase (PGI2s) has been localized in the endoplasmic reticulum of endothelial cells and in the nuclear and plasma membrane of smooth muscle cells. In human umbilical vein endothelial (HUVE) cells, we detected the enzyme in abundant cytoplasmic vesicles apparently originating from the plasma membrane and similar to those stained by gold-albumin, which interacts with a caveolar receptor. This prompted us to try a direct confocal microscopy approach aimed at colocalizing gold-albumin, caveolin-1, and PGI2 synthase. Moreover, the staining of HUVE cells with an anti-BiP7Grp78 antibody (a marker of endoplasmic reticulum) shows a perinuclear localization, sharply separated from PGI2 synthase localization. The results indicate that more than 80% of the enzyme resides in cellular sites costaining with caveolin-1 antibody and gold-albumin. This evidence was confirmed by the demonstration that PGI2 synthase and caveolin-1 coimmunoprecipitate in HUVE cell lysates and that they are associated to detergent-insoluble membrane domains in the same low-density fractions of a sucrose gradient. In addition, depletion of cellular cholesterol by mevalonate and methyl-beta-cyclodextrin leads to the shift of PGI2 synthase and caveolin-1 to higher density fractions of the gradient. Biochemical evidence about colocalization was supported by the use of a fusion protein glutathione S-transferase (GST)/caveolin-1, which retained either PGI2s purified from ram seminal vesicles or PGI2s present in HUVE cell lysates. Binding of PGI2s to caveolin "scaffolding domain" and to C-terminal region was deduced by using full-length GST--Cav-1, GST--Cav 61--101, and GST C- and N-terminal fusion proteins. A double approach based on the usage of filipin as a specific caveolae-disrupting agent and antisense oligonucleotides targeting PGI2 synthase mRNA suggests that the production of PGI2 in caveolae is likely to be connected to the regulation of angiogenesis, at least in vitro.

Glyceraldehyde-3-phosphate dehydrogenase is responsible for intranuclear localization of some oligonucleotides

Nuclear accumulation of ODNs has been associated with their binding to a series of nuclear proteins. These interactions could be responsible for the sequence-independent effects of ODNs as well as for their sequence-specific interactions and their intracellular distribution. Investigation of interaction of ODNs with these proteins may shed light on the mechanisms of cellular uptake and nuclear accumulation of oligonucleotides.

The Rossmann fold of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a nuclear docking site for antisense oligonucleotides containing a TAAAT motif

The subcellular localisation of oligodeoxynucleotides (ODN) is a major limitation for their use against nuclear targets. In this study we demonstrate that an antisense ODN directed against cytosolic phospholipase A(2) (cPLA2) mRNA is efficiently taken up and accumulates in the nuclei of endothelial cells (HUVEC), human monocytes and HeLa cells. Gel shift experiments and incubation of cells with oligonucleotide derivatives show that the anti-cPLA2 oligo binds a 37 kDa protein in nuclear extracts. The TAAAT sequence was identified as the major binding motif for the nuclear protein in competition experiments with mutated ODNs. Modification of the AAA triplet resulted in an ODN which failed to localise in the nucleus. Moreover, inserting a TAAAT motif into an ODN localising in the cytosol did not modify its localisation. The 37 kDa protein was purified and identified after peptide sequencing as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). It was shown by confocal microscopy that GAPDH co-localises with anti-cPLA2 ODN in the nucleus and commercial GAPDH effectively binds the oligo. Competition experiments with increasing concentration of NAD(+) co-factor indicate that the GAPDH Rossmann fold is a docking site for antisense oligonucleotides containing a TAAAT motif.

Knockdown of caveolin-1 by antisense oligonucleotides impairs angiogenesis in vitro and in vivo

Knock-out of the gene coding for caveolin-1, the main organizer of caveolae, has not yet been performed. We devised a strategy to knock-down caveolin-1 gene expression using antisense oligodeoxynucleotides (ODNs). Seven ODNs, covering different regions of caveolin-1 mRNA, were screened by Western blot analysis of caveolin-1 levels. The most active and specific was found to reduce caveolin-1 protein levels by 70% at 1 microM concentration and its action, as demonstrated by a marked reduction (about 50%) in caveolin-1 mRNA levels, was due to a true antisense mechanism. In HUVEC treated with the active ODN, caveolae were undetectable by confocal and electron microscopy, while their number was not affected when cells were treated with a scrambled ODN. Using the fibrin gel 3 D angiogenesis test we established that the active (but not the scrambled) ODN strongly suppressed capillary-like tube formation. Moreover, an antisense tailored against chicken caveolin-1 mRNA, when tested using the chorio-allantoic membrane technique, dramatically reduced vessel formation at doses (10-20 microg) under which control ODNs were ineffective and devoid of toxicity. Thus, it is likely that caveolin-1 down regulation, followed by caveolae disruption, impairs angiogenesis in vitro and in vivo.

A 38 kDa nuclear protein is involved in the retention of an antisense oligonucleotide directed against cytosolic phospholipase A2

Recent studies suggest that antisense phosphorothioate oligonucleotides (APO) are useful tools not only to impair gene expression, but also to modify the splicing of pre-mRNA, as the classical view that they act by suppressing the translation of mature mRNA has been challenged by several examples showing their nuclear site of action. In this work we show that an APO directed against cytosolic phospholipase A2 (cPLA2) mRNA localises in the nucleus and interacts with a specific nuclear protein.

Evidence that photodynamic stress kills Zellweger fibroblasts by a nonapoptotic mechanism

Zellweger fibroblasts, which are devoid of peroxisomes and fail to synthesize plasmalogens, are very sensitive to the killing effect triggered by UV-activated 12-(1-pyrene) dodecanoic acid (P12). Although in some studied performed, it is assumed that reactive oxygen species (ROS) may damage plasma membrane causing necrosis, other studies suggest that ROS are involved in apoptotic cell death induced by a wide variety of stimuli. Analysing the P12 dose-response in Zellweger fibroblasts, we observed that at high doses (1-2 microM), more than 75% of the cells died after 24 h. This behaviour suggested that, at high doses, P12 kills the cells by unspecific lytic mechanisms or by necrosis, while at low doses (0.1-0.5 microM), an apoptotic mechanism could be involved. Cytofluorimetric analysis of Zellweger fibroblasts-treated with activated P12 (0.5 microM) did not show morphological modifications typical of apoptotic cell death. This was supported by comparative staining of fibroblast nuclei, DNA gel electrophoresis and identification of poly(ADP-ribose) polymerase (PARP) cleavage and Bcl-2 expression, assayed by Western blots. Thus, our results, while confirming the importance of plasmalogens in the protection against ROS, establish that apoptosis is not involved in photodynamic death induced by activated P12. Therefore, we can expect that in gene transfer experiments, the rescue of Zellweger cells will be dependent only on the correction of peroxisomal biogenesis.

Expression of interleukin 15 (IL-15) in human rhabdomyosarcoma, osteosarcoma and Ewing's sarcoma

Interleukin 15 (IL-15) is a recently discovered cytokine that stimulates lymphocyte proliferation and migration via a trimeric receptor sharing the beta and gamma signal transducing chains with the IL-2 receptor. IL-15 is typically produced by normal cells that do not release IL-2, but little information is currently available on human tumors. To assess whether human musculo-skeletal sarcomas produce IL-15, we analyzed surgical specimens and cell lines obtained from rhabdomyosarcoma, osteosarcoma and Ewing's sarcoma. IL-15 mRNA was present in 9/9 surgical specimens (3 Ewing's sarcomas, 5 osteosarcomas and 1 rhabdomyosarcoma). The analysis of a panel of cell lines (7 derived from Ewing's sarcoma, 12 from osteosarcoma and 5 from rhabdomyosarcoma) showed that all rhabdomyosarcoma and osteosarcoma cell lines expressed IL-15 mRNA at levels ranging from low to high, while Ewing's sarcoma cells contained little or no IL-15 message. ELISA assays showed IL-15 release in a subset of rhabdomyosarcomas and osteosarcomas, but not in Ewing's sarcoma. The highest production of IL-15, in the picogram/ml range, was found in rhabdomyosarcoma cell lines RH30 and RD.

Expression of transduced carcinoembryonic antigen gene in human rhabdomyosarcoma inhibits metastasis

Carcinoembryonic antigen (CEA) is a highly glycosylated cell surface glycoprotein belonging to the immunoglobulin superfamily. CEA has been involved in vitro in adhesion mechanisms, but little is known about the function of this glycoprotein in vivo in normal tissue differentiation and malignancy. With regard to the relationship between CEA expression and tissue differentiation, it has been reported that transfection of the CEA gene in rat L6 myoblasts results in a complete block of myogenic differentiation. To extend investigations to the transformed myogenic counterpart and examine CEA effects on differentiation and malignancy outside the colon system, we have transfected the human CEA gene in human rhabdomyosarcoma cells. Human rhabdomyosarcoma cells transfected with the CEA gene correctly expressed membrane CEA anchored via glycosylphosphatidylinositol and secreted CEA in the medium. CEA gene transfer in human rhabdomyosarcoma cells, which display a limited differentiation ability, does not further inhibit myogenic differentiation or alter in vitro proliferation or natural killer sensitivity. CEA transfection does not affect s.c. growth in nude mice, but the ectopic expression of CEA in human rhabdomyosarcoma cells can strongly inhibit their metastatic ability to lungs and adrenals after i.v. injection. The impairment of metastatic potential correlates with a reduction in the homotypic adhesion properties of the cells. These data suggest that CEA, in some systems, can interfere with intercellular adhesion and, at least for cells not metastatic to the liver, can act as an anti-metastatic molecule.

Antisense epidermal growth factor receptor transfection impairs the proliferative ability of human rhabdomyosarcoma cells

Human rhabdomyosarcoma cells express membrane epidermal growth factor receptor (ECF-R), which could confer responsiveness to EGF and transforming growth factor-alpha (TGF-alpha) of autocrine or paracrine origin. To study the role played by this growth factor circuit in the proliferation and differentiation of myogenic neoplastic cells, human rhabdomyosarcoma EGF-R-expressing cells (RD/18 clone) have been transfected with a plasmid containing a fragment of the EGF-R cDNA in the antisense orientation. In vitro growth and differentiative ability were studied on six antisense-transfected clones (AS) in comparison to parental RD/18 cells and to cells transfected with the plasmid containing only the neomycin resistance gene (NEO). A reduced EGF-R membrane expression was found in AS clones by decreased immunofluorescence with an anti-EGF-R monoclonal antibody. All AS transfectants had a greatly impaired proliferative ability, even when cultured in fetal bovine serum-containing medium. Proliferation of AS clones was completely blocked in medium supplemented with 2% horse serum. The differentiation ability of AS clones was heterogeneous, ranging from clones with a percentage of myosin-positive cells higher than controls to clones with a negligible myosin expression. Therefore, the growth impairment determined by the loop interruption is not sufficient to switch on the differentiation program. The role played by EGF-R in the proliferation of human rhabdomyosarcoma cells suggests that this receptor could constitute a target for a therapeutic approach.

Redundancy of autocrine loops in human rhabdomyosarcoma cells: induction of differentiation by suramin

Three human rhabdomyosarcoma cell lines were used to investigate the presence of autocrine loops based on the production of insulin-like growth factor (IGF)-II, basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF)/transforming growth factor (TGF)-alpha and of their corresponding receptors, and whether these loops affect cell proliferation and myogenic differentiation. Two cell lines, RD/18 and CCA, deriving from tumours of the embryonal histotype, showed the presence of both growth factors and receptors which make possible three different autocrine loops, while the alveolar RMZ-RC2 cell line lacked that based on the EGF receptor. Culture of rhabdomyosarcoma cells in the presence of specific blocking antibodies, directed to a component of single autocrine loops, inhibited cell proliferation (up to 50%), without inducing myogenic differentiation. Suramin, a drug which non-selectively interferes with the binding of growth factors to their cellular receptors, was used to block all the autocrine loops simultaneously. In CCA and RMZ-RC2 cells suramin was able to induce a significant increase (up to 3-fold) in the proportion of myosin-positive cells over control cultures. Therefore rhabdomyosarcoma cells of embryonal and alveolar histotype can show a redundancy of growth-sustaining autocrine loops. Suramin could interfere with them by acting on both growth inhibition and induction of myogenic differentiation.