Arachnoiditis ossificans after spinal surgery.

This article presents an unusual case of arachnoiditis ossificans after spinal surgery. A case of arachnoiditis ossificans secondary to lumbar fixation and decompression surgery for the treatment of multilevel lumbar fractures is reported and the relevant literature is reviewed. A 29-year-old man who previously underwent posterior pedicle screw fixation and fusion for multiple lumbar spine fractures reported lower back stiffness and discomfort 23 months postoperatively. A laminectomy was performed at L2 and at L3-L4. At L2, bone fragments from the burst fracture had injured the dural sac and some nerve roots. A posterolateral fusion was performed using allogeneic bone. Postoperatively, there were no signs of fever, infection, or systemic inflammatory responses. Arachnoiditis ossificans of the thecal sac from L1-L5 was diagnosed by magnetic resonance imaging and computed tomography at the 2-year follow-up. His postoperative neurological status progressively improved and he regained motor and sensory functions. Because of neurological improvements, fixation hardware was removed without further decompression. The authors report a case of arachnoiditis ossificans secondary to lumbar fixation and decompression surgery, which involved a large region. Arachnoiditis ossificans is a relatively rare disorder with unclear etiologies and limited treatment options. Spinal surgical intervention of arachnoiditis ossificans should be carefully considered because it may lead to poor outcomes and multiple revision surgeries.

p53 inactivation upregulates p73 expression through E2F-1 mediated transcription.

While p73 overexpression has been associated with increased apoptosis in cancer tissues, p73 overexpressing tumors appear to be of high grade malignancy. Why this putative tumor suppressor is overexpressed in cancer cells and what the function of overexpressed p73 is in breast cancers are critical questions to be addressed. By investigating the effect of p53 inactivation on p73 expression, we found that both protein and mRNA levels of TAp73 were increased in MCF-7/p53siRNA cells, MCF-7/p53mt135 cells and HCT-116/p53-/- cells, as compared to wild type control, suggesting that p53 inactivation by various forms upregulates p73. We showed that p53 knockdown induced p73 was mainly regulated at the transcriptional level. However, although p53 has a putative binding site in the TAp73 promoter, deletion of this binding site did not affect p53 knockdown mediated activation of TAp73 promoter. Chromatin immuno-precipitation (ChIP) data demonstrated that loss of p53 results in enhanced occupancy of E2F-1 in the TAp73 promoter. The responsive sequence of p53 inactivation mediated p73 upregulation was mapped to the proximal promoter region of the TAp73 gene. To test the role of E2F-1 in p53 inactivation mediated regulation of p73 transcription, we found that p53 knockdown enhanced E2F-1 dependent p73 transcription, and mutations in E2F-1 binding sites in the TAp73 promoter abrogated p53 knockdown mediated activation of TAp73 promoter. Moreover, we demonstrated that p21 is a mediator of p53-E2F crosstalk in the regulation of p73 transcription. We concluded that p53 knockdown/inactivation may upregulate TAp73 expression through E2F-1 mediated transcriptional regulation. p53 inactivation mediated upregulation of p73 suggests an intrinsic rescuing mechanism in response to p53 mutation/inactivation. These findings support further analysis of the correlation between p53 status and p73 expression and its prognostic/predictive significance in human cancers.

Mutations in components of the Wnt signaling pathway in gastric cancer.

AIM: To explore the contribution of AXIN1, AXIN2 and beta-catenin, components of Wnt signaling pathway, to the carcinogenesis of gastric cancer (GC), we examined AXIN1, AXIN2 exon7 and CTNNB1 (encoding beta-catenin) exon3 mutations in 70 GCs. METHODS: The presence of mutations was identified by polymerase chain reaction (PCR)-based denaturing high-performance liquid chromatography and direct DNA sequencing. Beta-catenin expression was detected by immunohistochemical analysis. RESULTS: Among the 70 GCs, 5 (7.1%) had mutations in one or two of these three components. A frameshift mutation (1 bp deletion) in exon7 of AXIN2 was found in one case. Four cases, including the case with a mutation in AXIN2, had frameshift mutations and missense mutations in AXIN1. Five single nucleotide polymorphisms (SNPs), 334 C>T, 874 C>T, 1396 G>A, 1690 C>T and 1942 T>G, were identified in AXIN1. A frameshift mutation (27 bp deletion) spanning exon3 of CTNNB1 was observed in one case. All four cases with mutations in AXIN1 and AXIN2 showed nuclear beta-catenin expression. CONCLUSION: These data indicate that the mutations in AXIN1 and AXIN2 may contribute to gastric carcino-genesis.

Detection of frameshift mutations of RIZ in gastric cancers with microsatellite instability.

AIM: To study the frameshift mutations of the retinoblastoma protein-interacting zinc finger gene RIZ in gastric cancer with microsatellite instability, and to identify two coding polyadenosine tracts of RIZ. METHODS: Frameshift mutations at (A)8 and (A)9 tracts of RIZ were detected in 70 human gastric cancer (HGC) specimens by DHPLC and DNA sequencing. Microsatellite instability (MSI) status was assessed by two mononucleotide markers, BAT26 and BAT25, by means of denaturing high-performance liquid chromatography (DHPLC). RESULTS: In 70 HGC samples, 8 (11.4%) were found positive for instabilities at BAT26 and BAT25. In 7 of the 8 cases with instabilities at both BAT26 and BAT25 (MSI-H), 1 was unstable at BAT26 but stable at BAT25. Frameshift mutations were identified in 4 (57.1%) of the 7 samples with MSI-H in the (A)9 tract of RIZ without mutations in the (A)8 tract. In contrast, frameshift mutations were found in neither of the polyadenosine tracts in 63 samples of MSI-L or MSI stable tumors. Pro704 LOH detection in 4 cases with frameshift mutations did not find LOH in these cases. CONCLUSION: Frameshift mutations of RIZ may play an important role in gastric cancers with MSI.