Up-regulation of L1CAM in pancreatic duct cells is transforming growth factor beta1- and slug-dependent: role in malignant transformation of pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is thought to originate from ductal structures, exhibiting strong desmoplastic reaction with stromal pancreatic myofibroblasts (PMF), which are supposed to drive PDAC tumorigenesis. Previously, we observed high expression of the adhesion molecule L1CAM (CD171) in PDAC cells accounting for chemoresistance. Thus, this study aimed to investigate whether PMFs are involved in the induction of tumoral L1CAM and whether this contributes to malignant transformation of pancreatic ductal cells and PDAC tumorigenesis. Immunohistochemistry of tissues from chronic pancreatitis specimens revealed considerable L1CAM expression in ductal structures surrounded by dense fibrotic tissue, whereas no L1CAM staining was seen in normal pancreatic tissues. Using the human pancreatic duct cell line H6c7, we show that coculture with PMFs led to a transforming growth factor-beta1 (TGF-beta1)-dependent up-regulation of L1CAM expression. Similarly, L1CAM expression increased in monocultured H6c7 cells after administration of exogenous TGF-beta1. Both TGF-beta1- and PMF-induced L1CAM expression were independent of Smad proteins but required c-Jun NH(2)-terminal kinase activation leading to the induction of the transcription factor Slug. Moreover, Slug interacted with the L1CAM promoter, and its knockdown abrogated the TGF-beta1- and PMF-induced L1CAM expression. As a result of L1CAM expression, H6c7 cells acquired a chemoresistant and migratory phenotype. This mechanism of TGF-beta1-induced L1CAM expression and the resulting phenotype could be verified in the TGF-beta1-responsive PDAC cell lines Colo357 and Panc1. Our data provide new insights into the mechanisms of tumoral L1CAM induction and how PMFs contribute to malignant transformation of pancreatic duct cells early in PDAC tumorigenesis.

Role of myofibroblasts in innate chemoresistance of pancreatic carcinoma--epigenetic downregulation of caspases.

We recently reported on continuous tumor-stroma interactions essentially contributing to chemoresistance of pancreatic ductal adenocarcinoma (PDAC) cells. As demonstrated here, long-term coculture with pancreatic myofibroblasts representing the main stromal compartment of PDAC resulted in a chemoresistant phenotype in the pancreatic ductal epithelial cell line H6c7 as well as in the chemosensitive PDAC cell line T3M4. This involved a reduced expression of caspases and the caspase inducing transcription factor STAT1, both caused by diminished gene transcription. The DNA-methylation inhibitor 5-azadeoxycytidine enhanced caspase and STAT1 expression in cocultured H6c7 and T3M4 cells along with an increased chemosensitivity, indicating a role for CpG DNA-hypermethylation in the downregulation of these crucial apoptosis mediators. Cocultured H6c7 and T3M4 cells exhibited elevated nuclear levels of DNA-methyltransferase-1 (DNMT1). Silencing of DNMT1 expression by siRNA increased expression of caspases and STAT1 and restored chemosensitivity. In SCID mice, tumors arising from coinoculated T3M4 cells and myofibroblasts (co-tumors) responded less towards chemotherapy than mono-tumors, exhibiting decreased apoptosis, no remission and reduced expression of caspases and STAT1. These data underscore the role of myofibroblasts in chemoresistance of PDAC and point to the importance of caspases as central target structures of epigenetic regulation in this scenario. Furthermore, an activated microenvironment might apparently promote the manifestation of chemoresistance already in premalignant precursor cells at early stages of PDAC tumorigenesis.

In vitro assessment of motility and proliferation of human osteogenic cells on different isolated extracellular matrix components compared with enamel matrix derivative by continuous single-cell observation.

OBJECTIVES: The composition of the extracellular matrix (ECM) plays a substantial role in bone remodelling, fracture healing and osseointegration of dental implants by regulating proliferation, migration and finally differentiation of osteogenic cell populations. Emdogain, a composition of an enamel matrix derivative (EMD), has been introduced as a potential candidate to promote tissue regeneration. We investigated whether EMD could serve as a potential promoter of cell proliferation and motility as a dynamic cell response and compared the results with the ubiquitous single ECM components type I collagen and laminin. MATERIAL AND METHODS: In the investigation presented, we used a continuous observation method for the analysis of migratory and proliferative patterns of individual cells. We analyzed the response of four osteoblastic cell lines to specific extracellular ligands (type I collagen, laminin and EMD) over a period of 24 h compared with untreated glass surface and bovine serum albumin (BSA) as control groups. RESULTS: Type I collagen and laminin promoted cell motility significantly compared with the control groups and, in part, compared with EMD as well. The analysis of all 451 investigated cells revealed the following mean values for cell motiliy: untreated glass (n=99): 5.46+/-2.74 microm/h, BSA (n=89): 6.35+/-2.43 microm/h, type I collagen (n=108): 8.77+/-3.42 microm/h, laminin (n=74): 9.89+/-5.10 microm/h and EMD (n=81): 7.92+/-3.35 microm/h. Proliferation rates on the different surfaces were heterogenous for all investigated cell lines and varied from 0% to 50% within 24 h without a correlation to cell motility. CONCLUSION: In our study, EMD promotes cell motility better than the control groups. The two investigated single ECM components type I collagen and laminin promoted cell motility superior to EMD. This supports the hypothesis that EMD promotes a less mobile but more differentiated osteogenic phenotype.

Local intracerebral administration of O(6)-benzylguanine combined with systemic chemotherapy with temozolomide of a patient suffering from a recurrent glioblastoma.

The DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) is a major determinant of methylating anticancer drug resistance. Inactivation of MGMT by pseudosubstrate inhibitors, such as O(6)-benzylguanine (O(6)BG), sensitizes tumor cells to O(6)-alkylating agents. However, systemic administration of O(6)BG causes depletion of MGMT in all tissues of the body. Therefore, dose reduction of O(6)-alkylating drugs administered together with O(6)BG is required in order to avoid unwished toxic side effects. To attenuate the increased systemic toxicity caused by MGMT inhibitors, local MGMT inactivation would be desirable. Here, we report on intracerebral treatment with O(6)BG of a patient suffering from glioblastoma. O(6)BG was administered weekly in the tumor cavity by means of an Ommaya reservoir. This application was well tolerated. Concomitant treatment with temozolomide (Temodal) was associated with transient tumor stabilization without detectable side effects. Although evidence is still lacking that local O(6)BG administration caused MGMT to be depleted in the residual tumor, the trial shows that intracerebral treatment with O(6)BG is feasible. It might be a safe strategy for improving glioma therapy by treatment with temozolomide (and presumably also other O(6)-alkylating drugs) concomitant with O(6)BG without augmenting drug-induced systemic side effects.

Phase II trial of lomustine plus temozolomide chemotherapy in addition to radiotherapy in newly diagnosed glioblastoma: UKT-03.

PURPOSE: To evaluate toxicity and efficacy of the combination of lomustine, temozolomide (TMZ) and involved-field radiotherapy in patients with newly diagnosed glioblastoma (GBM). PATIENTS AND METHODS: Thirty-one adult patients (median Karnofsky performance score 90; median age, 51 years) accrued in two centers received involved-field radiotherapy (60 Gy in 2-Gy fractions) and chemotherapy with lomustine 100 mg/m2 (day 1) and TMZ 100 mg/m2/d (days 2 to 6) with individual dose adjustments according to hematologic toxicity. RESULTS: A median of five courses (range, one to six courses) were delivered. WHO grade 4 hematotoxicity was observed in five patients (16%) and one of these patients died as a result of septicemia. Nonhematologic toxicity included one patient with WHO grade 4 drug-induced hepatitis (leading to discontinuation of lomustine and TMZ) and one patient with WHO grade 2 lung fibrosis (leading to discontinuation of lomustine). The progression-free survival (PFS) rate at 6 months was 61.3%. The median PFS was 9 months (95% CI, 5.3 to 11.7 months), the median overall survival time (MST) was 22.6 months (95% CI, 12.5 to not assessable), the 2-year survival rate was 44.7%. O6-methylguanine-DNA methyltransferase (MGMT) gene-promoter methylation in the tumor tissue was associated with longer PFS (P = .014, log-rank test) and MST (P = .037). CONCLUSION: The combination of lomustine, TMZ, and radiotherapy had acceptable toxicity and yielded promising survival data in patients with newly diagnosed GBM. MGMT gene-promoter methylation was a strong predictor of survival.

Mechanisms of failure after endoscopic third ventriculostomy in young infants.

OBJECT: The cause of failed endoscopic third vetriculostomy (ETV) surgery in the treatment of hydrocephalus may be a poor absorption of cerebrospinal fluid (CSF) or a new or continuing obstruction of CSF pathways. Particularly in infants, ETV failures often are ascribed to a still poorly developed CSF absorptive capacity. METHODS: The authors report on a series of 11 infants younger than 1 year of age undergoing at least one repeated endoscopic surgery after a failed initial ETV for aqueductal stenosis. The following three patterns of endoscopic findings were observed: 1) reclosure of the ventriculostoma; 2) narrowing of the ventriculostoma; and 3) patent ventriculostoma with new arachnoid membranes in the basal cisterns below the floor of the third ventricle, not present at the time of the first ETV. In all patients, a new obstruction of CSF pathways was seen during repeated ETV or shunt surgery. CONCLUSIONS: The authors' data strongly suggest that CSF pathway reclosure is the factor most responsible for ETV failure in obstructive hydrocephalus. According to both their experiences and to studies published in the literature, the formation of new arachnoid membranes or scars plays a far greater role in ETV failure than does poor CSF absorption, at least in aqueductal stenosis. It is hypothesized that infants have a higher tendency to form new arachnoid membranes than do older patients and that this factor may explain (at least in part) the higher ETV failure rate in patients younger than 1 year old.

Endoscopic third ventriculostomy in infants of less than 1 year of age: which factors influence the outcome?

OBJECTIVES: Endoscopic third ventriculostomy (ETV) is a successful method of treatment for obstructive hydrocephalus. In infants, however, it is reported to have a higher failure rate. On the basis of our own data and a meta-analysis of the literature, we try to define factors prognosticating potential failure in infants aged less than 1 year. METHODS: Data were collected retrospectively. Between October 1994 and October 2002, 20 ETVs were performed in 16 patients younger than 1 year. Ages ranged from 8 to 311 days (median 103). Etiology was aqueductal stenosis in all 16 patients (idiopathic in 7, posthemorrhagic in 3, postmeningitic in 3, and related to CNS or vascular malformation in 3). ETV failure was defined as subsequent need for shunt implantation. For non-shunted patients, follow up was 16-52 months (median 25). RESULTS: ETV was successful in 5 patients and eventually failed in 11. There was no mortality or permanent morbidity following ETV. In the successful cases, etiology was idiopathic aqueductal stenosis in 4 and postmeningitic aqueductal stenosis in 1; the median age was 206 days (range 82-311). In the 11 unsuccessful patients, it was idiopathic aqueductal stenosis in 3, posthemorrhagic in 3, postmeningitic in 2 and CNS/vascular malformation in 3 cases; median age was 94 days (range 8-299). Median time interval between (last) ETV and shunt was 38 days (range 2-70). The difference in median age between the success group and the failure group roughly corresponded to data gained from a meta-analysis of the literature. Four patients underwent a second ETV. In intraoperative ventriculoscopy, the stoma was closed or there were new membranes below the floor of the third ventricle and a second ETV was performed. But finally, all re-ETVs failed and the patients needed a shunt. CONCLUSION: Factors indicating potential failure of ETV were very young age and etiology other than idiopathic aqueductal stenosis. Probability of success seems to increase during the first 2 or 3 months of life. Ventriculoscopy with the option of a second ETV should be regularly performed after failure of ETV.

Spinal rhabdomyosarcoma in a child with lipomyelomeningocele.

Malignant tumors arising within dysrhaphic malformations are very rare and are mostly teratomas; so far, only one rhabdomyosarcoma has been reported in this context. We report another case of a girl with lipomyelomeningocele who developed a lumbar rhabdomyosarcoma 2 years after birth and primary closure of the neural tube defect. We present clinical, radiological and pathological findings, discuss possible mechanisms of malignant transformation and review the literature.