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.

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.

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.

Mesenchymal stem cells from patients to assay bone graft substitutes.

Bio-engineered scaffolds used in orthopedic clinical applications induce different tissue responses after implantation. In this study, non-stoichiometric Mg(2+) ions and stoichiometric apatites, which are used in orthopedic surgery as bone substitutes, have been assayed in vitro with human adult mesenchymal stem cells (hMSC) to evaluate cytocompatibility and osteoconductivity. hMSCs from the bone marrow aspirates of orthopedic patients were isolated and analyzed by flow cytometry for the surface markers Stro1, CD29, CD44, CD71, CD73, CD90, CD105 (positive) and CD45, CD235 (negative). The hMSC were analyzed for self-renewal capacity and for differentiation potential. The hMSC, which were grown on different biomaterials, were analyzed for (i) cytotoxicity by AlamarBlue metabolic assay, (ii) osteoconductivity by ELISA for activated focal adhesion kinase, (iii) cytoskeleton organization by fluorescence microscopy, and (iv) cell morphology which was investigated by scan electron microscopy (SEM). Results indicate that isolated cell populations agree with minimal criteria for defining hMSC cultures. Non-stoichiometric Mg(2+) and stoichiometric apatites, in granular form, represent a more favorable environment for mesenchymal stem cell adhesion and growth compared to the non-stoichiometric Mg(2+) apatite, in nano-structured paste form. This study indicates that different forms of biomaterials modulate osteoconductivity and cellular growth by differential activation focal adhesion kinase.

Navigation-assisted surgery for tumors of the spine.

PURPOSE: Computer-assisted navigation systems are largely used for pedicle screws positioning in degenerative and traumatic spine surgery. In oncologic spine surgery its use is still developing and could be extended for tumor identification and excision. Aim of this paper is to present our experience. METHODS: Seven selected patients (5 females, 2 males), mean age 44 years (min 17-max 62) affected by primary benign or malignant tumors of the spine or spine metastases were surgically treated with the use of computer-assisted navigation system from March to October 2011. RESULTS: At 18 months mean F.U. (min 15-max 23), no LR were observed. Revision surgery was necessary only in one case for C1 pedicle screw malpositioning. CONCLUSIONS: Navigation system can improve surgical accuracy in screws placement and tumor localization and excision. Learning curve and technical aspects must be considered to avoid potential serious mistakes.

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.

Spinal infection multidisciplinary management project (SIMP): from diagnosis to treatment guideline.

Spine infections require a multidisciplinary approach to be treated and solved. A guide line to drive physicians in the deep complexity of such a disease is extremely helpful. SIMP suggests a flow-chart built up on clear concepts such as right and well managed antibiotic therapy, sound stability of the spine, correct and smart use of the standard and functional imaging techniques, such as f18 FDG PET/CT. In 16 months a total of 41 patients have been treated for spondylodiscitis, discitis and vertebral osteomyelitis by our team of physicians and 25 patients have been enrolled in a prospective study whose target is the assessment of the SIMP flow-chart and of every single aspect that characterize it.

The impact of SARS-CoV-2 pandemic on Oncologic and Degenerative Spine Surgery Department activity: the experience of Rizzoli Orthopaedic Institute under COVID-19 lockdown.

OBJECTIVE: Experience of Department of Oncologic and Degenerative Spine Surgery of Rizzoli Orthopaedic Institute during SARS-CoV-2 pandemic lockdown. PATIENTS AND METHODS: Retrospective observational study of surgically treated patients from 09th March 2020 to 04th May 2020. DATA COLLECTED: age, sex, type of disease, neurological status, days of hospitalization, complications and type of discharge. A comparison analysis with same period of the last year was performed in order to evaluate the impact of COVID-19 spreading on daily surgical activity. RESULTS: A total of 107 surgical procedures in 102 patients were performed from 09th March 2020 to 04th May 2020. Analysis showed a statistically significant difference in age, sex, ASIA class and type of treated disease compared to the same period of the last year (p=0.042, 0.006, 0.022 and 0.007, respectively). No statistically significant differences were observed in type of discharge, length of hospitalization and complications (p= 0.447, 0.261 and 0.127, respectively). 3 COVID-19 infections have been identified in hospitalized patients. 1 COVID-19 patient wad admitted from Emergency Department and was managed according to a dedicated path. CONCLUSIONS: Surgical activity was paradoxically increased during SARS-CoV-2 pandemic lockdown through the management of urgent and non-deferrable spinal disease with a low rate (3,9%) of COVID-19 infections.

Efficacy and safety of a novel hydrogel (HYADD4-G) in degenerative disc disease patients: a multicentric open label study.

OBJECTIVE: In this premarket clinical study, we evaluated the efficacy and safety of a novel Hydrogel (HYADD4-G) for reducing low back pain (LBP) in patients with degenerative disc disease (DDD). PATIENTS AND METHODS: Twenty-three patients with chronic LBP were enrolled. All patients presented with up to three lumbar black discs (Pfirrmann grade III or IV), LBP of at least 40 mm on the Visual Analogue Scale (VAS), and a Roland-Morris Disability Questionnaire (RMDQ) score of at least 9. Patients received a single 1.5 ml intradiscal injection of HYADD4-G (8 mg/ml), guided by X-ray. Our primary endpoint was the change in VAS score from baseline (day 0) to 4, 12, and 24 weeks. Our secondary endpoints were black disc hydration by Magnetic Resonance Imaging (MRI); the patient's therapeutic response according to the RMDQ; the quality of life, as determined by the EuroQol-5 Dimension (EQ-5D) Index; and a global assessment of patient health status, safety, and local tolerability. RESULTS: Compared with baseline values, VAS score showed a significant reduction at each time point, and across the overall 24-week follow-up period (p < 0.0001). MRI scanning observed a significant reduction in Pfirrmann grade from baseline, by at least one grade, at both week 4 (p = 0.0039) and week 24 (p = 0.0010). Furthermore, compared with baseline values, there was a significant reduction in RMDQ score at each timepoint, and across the entire study period (p < 0.0001). The EQ-5D index increased significantly from baseline to week 24 (p = 0.0001). Finally, mean VAS scores for Patient Global Assessment (PTGA), and Clinical Observer Global Assessment (COGA), decreased significantly at each time point (p < 0.0001), except for week 4. CONCLUSIONS: HYADD4-G proved to be an efficient reliever of low back pain due to DDD.

A Rationale for the Use of Clotted Vertebral Bone Marrow to Aid Tissue Regeneration Following Spinal Surgery.

Vertebral body bone marrow aspirate (V-BMA), easily accessible simultaneously with the preparation of the site for pedicle screw insertion during spinal procedures, is becoming an increasingly used cell therapy approach in spinal surgery. However, the main drawbacks for V-BMA use are the lack of a standardized procedure and of a structural texture with the possibility of diffusion away from the implant site. The aim of this study was to evaluate, characterize and compare the biological characteristics of MSCs from clotted V-BMA and MSCs from whole and concentrate V-BMAs. MSCs from clotted V-BMA showed the highest cell viability and growth factors expression (TGF-ß, VEGF-A, FGF2), the greatest colony forming unit (CFU) potency, cellular homogeneity, ability to differentiate towards the osteogenic (COL1AI, TNFRSF11B, BGLAP) and chondrogenic phenotype (SOX9) and the lowest ability to differentiate toward the adipogenic lineage (ADIPOQ) in comparison to all the other culture conditions. Additionally, results revealed that MSCs, differently isolated, expressed different level of HOX and TALE signatures and that PBX1 and MEIS3 were down-regulated in MSCs from clotted V-BMA in comparison to concentrated one. The study demonstrated for the first time that the cellular source inside the clotted V-BMA showed the best biological properties, representing an alternative and advanced cell therapy approach for patients undergoing spinal surgery.

Spinal tuberculosis: proposed spinal infection multidisciplinary management project (SIMP) flow chart revision.

OBJECTIVE: We propose a revised flow chart of spinal infection multidisciplinary management project (SIMP) aimed to standardize the diagnostic process and management of spinal tuberculosis (TB). MATERIALS AND METHODS: We reviewed data from all TB cases with osteoarticular involvement treated at a large tertiary teaching hospital in Bologna, Northern Italy, from January 2013 to December 2017. We cross-linked notified osteoarticular TB cases with SIMP database and we analysed clinical, diagnostic, and treatment data of all cases managed by SIMP. RESULTS: Osteoarticular TB accounted for the 7.8% (n=40) of all TB cases notified between 2013 and 2017 (N=513). Among the identified cases, 52% (n=21/40) had spine involvement: all were enrolled and evaluated by SIMP multidisciplinary group. Females accounted for 57% (12/21) of patients, the median age was 52 years (range 24-82). In the 67% (n=14/21) of cases, the major clinical symptom of spinal TB was back pain reported for a median of 4.5 months (range 1-12 months) before hospital admission. The interferon gamma release assay was positive in 75% (n=16/21) of patients. All patients performed MRI with gadolinium, which indicated spondylodiscitis in 90%. 18F-FDG-PET/CT revealed average maximum standardized uptake value (SUV max) of 12.54 (range 5.3-22) in 17/19 (89.5%). Bacteriological confirmation of TB was obtained in 86% of cases (n=18/21). One-third of patients (7/21) underwent surgery and 95% successfully completed the anti-TB treatment. CONCLUSIONS: Our data reveal that a multidisciplinary approach to spine tuberculosis facilitates early and accurate diagnosis and can improve medical and surgical management of this disease.

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.

Carbon ions therapy as single treatment in chordoma of the sacrum. Histologic and metabolic outcome studies.

OBJECTIVE: Even though carbon ions treatment (CIRT) of sacral chordoma (SC) substantially reduces tumor mass, tumor remnants are observed in most patients. Differentiating tumor remnants from necrosis is challenging, expensive in terms of imaging and time-consuming. So far, there has not been a systematic histological and metabolic analysis of post-CIRT lesions. We designed a prospective study aiming to histologically a metabolically differentiate between viable tumor and foci of necrosis and of fibrosclerosis after CIRT and correlate these findings to clinical outcome in patients with SC. PATIENTS AND METHODS: Between January 2013 and December 2016 18 patients, 12 males and 6 females, with histological confirmation of sacral chordoma, underwent CIRT. The total dose was 70.4 GyE, with a daily fraction of 4.4 GyE, for 4 weeks. MRI was performed every three months after treatment. FDG PET-CT scan and CT-guided needle biopsy were performed 6-12 months after CIRT. The incidence of complications (intraoperative and postoperative), local control (LC), overall survival (OS) and progression-free survival (PFS), changes in neurological status, clinical outcomes and toxicity were considered. RESULTS: All histological analysis but 2 reported signs of necrosis and of fibrosclerosis after CIRT. One of these 2 patients turned into a dedifferentiated chordoma. Radiological partial response (PR) was observed in 10 patients (56.3%) and stable disease (SD) in 5 patients (28.3). Two patients (11%) had a local relapse. The overall survival rate was 100% at 24 months. FDG PET CT after CIRT showed uptake decreasing compared with the baseline exam in all but one patient. CONCLUSIONS: The histological presence of necrosis and of fibrosclerosis after CIRT at the histological analysis supports the previous clinical evidence on the efficacy of CIRT. Volumetric stability of the residual mass should be considered as a success of treatment. In cases of a volumetric increase of the mass, a CT needle biopsy should always be performed. In our series, during the follow-up, the FDG-PET was able to promptly detect an increased uptake in the case which later was histologically defined as dedifferentiated chordoma.

Thoracoplasty in the surgical treatment of adolescent idiopathic scoliosis.

A consecutive series of 40 adolescents surgically treated between 1998-2001, by posterior spinal fusion and thoracoplasty were compared with a similar group of 40 adolescents treated in the same period by posterior only segmental fusion. Clinical and radiographic analysis was performed, including the SRS-30 questionnaire and Pulmonary Function Tests (PFT). Minimum five years follow-up was requested. No statistical differences were found between the two groups in PFT's both pre-operatively and at latest follow up. Our findings suggest that thoracoplasty did not adversely affected long-term PFT's in AIS patients treated by posterior spinal fusion alone.

BK virus-plasmid expression vector that persists episomally in human cells and shuttles into Escherichia coli.

We describe a novel expression vector, pBK TK-1, that persists episomally in human cells that can be shuttled into bacteria. This vector includes sequences from BK virus (BKV), the thymidine kinase (TK) gene of herpes simplex virus type 1, and plasmid pML-1. TK+-transformed HeLa and 143 B cells contained predominantly full-length episomes. There were typically 20 to 40 (HeLa) and 75 to 120 143 B vector copies per cell, although some 143 B transformants contained hundreds. Low-molecular-weight DNA from TK+-transformed cells introduced into Escherichia coli were recovered as plasmids that were indistinguishable from the input vector. Removal of selective pressure had no apparent effect upon the episomal status of pBK TK-1 molecules in TK+-transformed cells. BKV T antigen may play a role in episomal replication of pBK TK-1 since this viral protein was expressed in TK+ transformants and since a plasmid that contained only the BKV origin of replication was highly amplified in BKV-transformed human cells that synthesize BKV T antigen.

High incidence of ependymomas induced by BK virus, a human papovavirus: brief communication.

Ependymomas were produced in 44 of 50 Syrian golden hamsters and in 9 of 31 outbred Swiss mice inoculated intracerebrally with high-titer, purified BK virus (BKV). Tumors contained a T-antigen that reacted with BKV-specific T-antibody in immunofluorescence and complement-fixation tests. A proportion of tumor-bearing animals had antibodies to BKV T-antigen in their sera. BKV could be rescued from two tumor cell lines by Sendal virus-mediated fusion with Vero cells. A low, or lack of, oncogenic activity was displayed by BKV inoculated sc, ip, or iv.

Ependymomas, malignant tumors of pancreatic islets, and osteosarcomas induced in hamsters by BK virus, a human papovavirus.

BK virus (BKV), a human papovavirus, was inoculated iv into 3-week-old Syrian golden hamsters. Between 2 1/2 and 9 months after inoculation, 82% of the animals developed tumors. The induced neoplasms were ependymoma, carcinoma of the pancreatic islets, osteosarcoma, adenocarcinoma, angiosarcoma, angioma, lymphoma, and seminoma. Hypersecretion of insulin, glucagon, C-peptide, and calcitonin was detected in tumors of pancreatic islets. BKV etiology of tumors was supported by the following evidence: 1) No tumors with BKV-specific markers appeared in animals given injections of buffer, animals inoculated with BKV neutralized by anti-BKV-specific serum, or uninoculated controls; 2) BKV tumor (T) antigen was detected by immunofluorescence and complement fixation tests in tumors of animals inoculated with infectious BKV and in transplanted tumors; 3) antibodies to BKV T-antigen were detected in sera of animals bearing primary or transplanted tumors; 4) BKV could be activated by Sendai virus-mediated fusion of neoplastic cells with susceptible Vero cells; and 5) no endogenous hamster oncornaviruses were found in tumors.

The coding region of the Bloom syndrome BLM gene and of the CBL proto-oncogene is mutated in genetically unstable sporadic gastrointestinal tumors.

Microsatellite instability (MSI) characterizes the hereditary nonpolyposis colorectal cancer syndrome but is also found in sporadic tumors. Frameshifts in microsatellites found in the coding regions (CDRs) of the TGFbeta1-RII, IGFIIR, hMSH3, hMSH6, and BAX genes indicate that MSI is involved in tumorigenesis by targeting genes that are directly implicated in the tumorigenic process. To identify additional genes targeted for MSI, we performed an analysis of the GenBank database that revealed 21 microsatellite repeats located in the CDR of 18 genes (12% of the analyzed sequences) whose function could be potentially associated with the tumorigenic process. Mutational studies of 57 sporadic gastrointestinal tumor DNAs revealed the presence of length variations in three of them: (a) BLM; (b) CBL; and (c) HOXA1. In the BLM gene, we found a frameshift mutation in a polyadenine repeat, whereas in the CBL proto-oncogene, an expansion of a trinucleotide repeat was detected with no translation shift. These alterations were present in 18 and 9%, respectively, of the genetically unstable sporadic gastrointestinal tumors analyzed, but in none of the cancers without the mutator phenotype. These changes were present in the DNA from the tumor but not in that from normal cells of the same patient. The HOXA1 retraction of a trinucleotide repeat was as frequent in both types of cancers and was also found in some normal paired tissues, therefore behaving as a neutral polymorphism. Our data extend the spectrum of unstable microsatellites located in gene CDRs and suggest that BLM and possibly CBL are involved in gastrointestinal tumorigenesis. Based on its proposed function, the BLM gene could represent a link between MSI and chromosomal instability pathways, because MSI targeting of the BLM gene could generate hypermutability and/or chromosomal instability.

GOK: a gene at 11p15 involved in rhabdomyosarcoma and rhabdoid tumor development.

The expression of GOK, a gene recently identified at 11p15.5, was studied in breast cancer, rhabdomyosarcoma, and rhabdoid tumor cell lines. In these neoplasms, deletions at 11p15 and suppression of tumorigenicity induced by a normal human chromosome 11 were previously demonstrated. Whereas breast cancer cell lines express readily detectable levels of GOK mRNA, expression is absent in rhabdomyosarcoma and rhabdoid tumor cell lines. This is in contrast with the high expression of GOK in skeletal muscle, the normal tissue of origin of rhabdomyosarcomas, suggesting that down-regulation of GOK expression could be involved in tumor development. In agreement with this hypothesis, transfection of GOK cDNA into G401 derived from a rhabdoid tumor and RD cells derived from a rhabdomyosarcoma that do not express detectable levels of GOK mRNA, induced cell death. Because GOK expression is not compatible with growth of these tumor cells, these results support the hypothesis that loss of GOK expression plays a role in tumor establishment or progression and suggest that GOK may act as a recessive tumor suppressor gene in rhabdomyosarcomas and rhabdoid tumors. On the contrary, transfection of GOK cDNA into the breast cancer cell line HBL100 produced no detectable effects, indicating that the growth-suppressive effect of GOK in RD and G401 cells was specific. Because rhabdomyosarcomas have been observed in cases of Beckwith-Wiedemann syndrome, a genetic disorder linked to 11p15, a role of GOK in this disease cannot be excluded.