Measuring CSF shunt flow with MRI using flow enhancement of signal intensity (FENSI).

PURPOSE: To develop and validate a noninvasive imaging technique for accurately assessing very slow CSF flow within shunt tubes in pediatric patients with hydrocephalus, aiming to identify obstructions that might impede CSF drainage. THEORY AND METHODS: A simulation of shunt flow enhancement of signal intensity (shunt-FENSI) signal is used to establish the relationship between signal change and flow rate. The quantification of flow enhancement of signal intensity data involves normalization, curve fitting, and calibration to match simulated data. Additionally, a phase sweep method is introduced to accommodate the impact of magnetic field inhomogeneity on the flow measurement. The method is tested in flow phantoms, healthy adults, intensive care unit patients with external ventricular drains (EVD), and shunt patients. EVDs enable shunt-flow measurements to be acquired with a ground truth measure of CSF drainage. RESULTS: The flow-rate-to-signal simulation establishes signal-flow relationships and takes into account the T1 of draining fluid. The phase sweep method accurately accounts for phase accumulation due to frequency offsets at the shunt. Results in phantom and healthy human participants reveal reliable quantification of flow rates using controlled flows and agreement with the flow simulation. EVD patients display reliable measures of flow rates. Shunt patient results demonstrate feasibility of the method and consistent flow rates for functional shunts. CONCLUSION: The results demonstrate the technique's applicability, accuracy, and potential for diagnosing and noninvasively monitoring hydrocephalus. Limitations of the current approach include a high sensitivity to motion and strict requirement of imaging slice prescription.

Brain stiffness following recovery in a patient with an episode of low-pressure hydrocephalus: case report.

The authors describe a follow-up to a case of a 19-year-old female with shunted aqueductal stenosis who presented with low-pressure hydrocephalus during a shunt malfunction. Shortly after management with CSF drainage at negative pressure, a magnetic resonance elastography scan was performed and revealed very low brain stiffness (high compliance). Here we present the case of the same patient seen 2 years later, now 21 years old, who again received a magnetic resonance elastography scan after receiving treatment for another shunt malfunction, this time with high intracranial pressure. This scan revealed recovery of brain stiffness to a near normal value for the patients' age. This observation suggests the low brain stiffness observed during the low-pressure hydrocephalus event is reversible. The authors discuss these findings in relation to biomechanical hypotheses of low-pressure hydrocephalus.

Magnetic Resonance Elastography Demonstrating Low Brain Stiffness in a Patient with Low-Pressure Hydrocephalus: Case Report.

The authors describe the case of a 19-year-old female with shunted aqueductal stenosis who presented with low-pressure hydrocephalus that responded to negative pressure drainage. A magnetic resonance elastography scan performed 3 weeks later demonstrated very low brain tissue stiffness (high brain tissue compliance). An analysis of the importance of this finding in understanding this rare condition is discussed.

Local mechanical properties of white matter structures in the human brain.

The noninvasive measurement of the mechanical properties of brain tissue using magnetic resonance elastography (MRE) has emerged as a promising method for investigating neurological disorders. To date, brain MRE investigations have been limited to reporting global mechanical properties, though quantification of the stiffness of specific structures in the white matter architecture may be valuable in assessing the localized effects of disease. This paper reports the mechanical properties of the corpus callosum and corona radiata measured in healthy volunteers using MRE and atlas-based segmentation. Both structures were found to be significantly stiffer than overall white matter, with the corpus callosum exhibiting greater stiffness and less viscous damping than the corona radiata. Reliability of both local and global measures was assessed through repeated experiments, and the coefficient of variation for each measure was less than 10%. Mechanical properties within the corpus callosum and corona radiata demonstrated correlations with measures from diffusion tensor imaging pertaining to axonal microstructure.

Management of brain metastasis. Surgical resection versus stereotactic radiotherapy: a meta-analysis.

Background: Treatment of metastatic brain tumors often involves radiotherapy with or without surgical resection as the first step. However, the indications for when to use surgery are not clearly defined for certain tumor sizes and multiplicity. This study seeks to determine whether resection of brain metastases versus exclusive radiotherapy provided improved survival and local control in cases where metastases are limited in number and diameter. Methods: According to PRISMA guidelines, this meta-analysis compares outcomes from treatment of a median number of brain metastases ≤ 4 with a median diameter ≤ 4 cm with exclusive radiotherapy versus surgery followed by radiotherapy. Four randomized control trials and 11 observational studies (1693 patients) met inclusion criteria. For analysis, studies were grouped based on whether radiation involved stereotactic radiosurgery (SRS) or whole-brain radiotherapy (WBRT). Results: In both analyses, there was no difference in survival between surgery ± SRS versus SRS alone two years after treatment (OR 1.89 (95% CI: 0.47-7.55, P = .23) or surgery + WBRT versus radiotherapy alone (either WBRT and/or SRS) (OR 1.18 (95% CI: 0.76-1.84, P = .46). However, surgical patients demonstrated greater risk for local tumor recurrence compared to SRS alone (OR 2.20 (95% CI: 1.49-3.25, P < .0001)) and compared to WBRT/SRS (OR 2.93; 95% CI: 1.68-5.13, P = .0002). Conclusion: The higher incidence of local tumor recurrence for surgical patients suggests that more prospective studies are needed to clarify outcomes for treatment of 1-4 metastasis less than 4 cm diameter.

High-resolution diffusion tensor imaging of the human pons with a reduced field-of-view, multishot, variable-density, spiral acquisition at 3 T.

Diffusion tensor imaging of localized anatomic regions, such as brainstem, cervical spinal cord, and optic nerve, is challenging because of the existence of significant susceptibility differences, severe physiologic motion in the surrounding tissues, and the need for high spatial resolution to resolve the underlying complex neuroarchitecture. The aim of the methodology presented here is to achieve high-resolution diffusion tensor imaging in localized regions of the central nervous system that is motion insensitive and immune to susceptibility while acquiring a set of two-dimensional images with more than six diffusion encoding directions within a reasonable total scan time. We accomplish this aim by implementing self-navigated, multishot, variable-density, spiral encoding with outer volume suppression. We establish scan protocols for achieving equal signal-to-noise ratio at 1.2 mm and 0.8 mm in-plane resolution for reduced field-of-view diffusion tensor imaging of the brainstem. In vivo application of the technique on the human pons of three subjects shows a clear delineation of the multiple local neural tracts. By comparing scans acquired with varying in-plane resolution but with constant signal-to-noise ratio, we demonstrate that increasing the resolution and reducing the partial volume effect result in higher fractional anisotropy values for the corticospinal tracts.

Cauda equina syndrome (CES) from lumbar disc herniations.

STUDY DESIGN: A retrospective review was performed to determine the outcomes of patients with cauda equina syndrome (CES) from a herniated lumbar disc at our institutions. OBJECTIVE: CES from lumbar herniated discs is considered the only absolute indication for surgery. It is considered a neurosurgical emergency with the outcome related to how quickly it is diagnosed and treated. The results of recovery of bladder function are felt by many authors to be related to early diagnosis and surgical intervention. Most authors recommend a wide decompressive laminectomy when surgery is performed. We reviewed our cases to determine if they conformed to these assumptions. SUMMARY OF BACKGROUND DATA: Although many articles regarding the outcome of CES from herniated lumbar discs suggest that early surgery is superior to surgery that is delayed, others have demonstrated no correlation between time-to-surgery and chances for recovery of neurologic and bladder function. METHODS: A retrospective review of all patients with lumbar herniated discs and CES from the years 1985 to 2004 was carried out. There were 31 patients, 28 of whom had bladder incontinence or retention requiring catheterization. Six patients were operated within 24 hours, 8 between 24 and 48 hours, and 17 after 48 hours (range: 60 h to 2 wk). Average follow-up was 5 years. RESULTS: Twenty-seven of these patients regained continence not requiring catheterization. There was no correlation between the time-to-surgery and recovery of bladder function. There was also no correlation between the time-to-surgery and recovery of motor and sensory function. The majority of patients underwent unilateral hemilaminotomy or bilateral hemilaminotomies; decompressive laminectomy was reserved for patients with underlying spinal stenosis or posteriorly herniated fragments. All of the patients were relieved of their radicular pain. CONCLUSIONS: In our series of patients with CES and bladder incontinence or retention, over 90% regained continence. Recovery of function was not related to the time to surgical intervention. The majority of the patients were adequately treated without the need for a complete laminectomy.

Intraperitoneal injection of a hairpin RNA-expressing plasmid targeting urokinase-type plasminogen activator (uPA) receptor and uPA retards angiogenesis and inhibits intracranial tumor growth in nude mice.

PURPOSE: The purpose of this study was to evaluate the therapeutic potential of using plasmid-expressed RNA interference (RNAi) targeting urokinase-type plasminogen activator (uPA) receptor (uPAR) and uPA to treat human glioma. EXPERIMENTAL DESIGN: In the present study, we have used plasmid-based RNAi to simultaneously down-regulate the expression of uPAR and uPA in SNB19 glioma cell lines and epidermal growth factor receptor (EGFR)--overexpressing 4910 human glioma xenografts in vitro and in vivo, and evaluate the i.p. route for RNAi-expressing plasmid administered to target intracranial glioma. RESULTS: Plasmid-mediated RNAi targeting uPAR and uPA did not induce OAS1 expression as seen from reverse transcription-PCR analysis. In 4910 EGFR-overexpressing cells, down-regulation of uPAR and uPA induced the down-regulation of EGFR and vascular endothelial growth factor and inhibited angiogenesis in both in vitro and in vivo angiogenic assays. In addition, invasion and migration were inhibited as indicated by in vitro spheroid cell migration, Matrigel invasion, and spheroid invasion assays. We did not observe OAS1 expression in mice with preestablished intracranial tumors, which were given i.p. injections of plasmid-expressing small interfering RNA--targeting uPAR and uPA. Furthermore, the small interfering RNA plasmid targeting uPAR and uPA caused regression of preestablished intracranial tumors when compared with the control mice. CONCLUSION: In conclusion, the plasmid-expressed RNAi targeting uPAR and uPA via the i.p. route has potential clinical applications for the treatment of glioma.

Transfection with anti-p65 intrabody suppresses invasion and angiogenesis in glioma cells by blocking nuclear factor-kappaB transcriptional activity.

PURPOSE: The strategy of intracellular antibodies to neutralize the function of target proteins has been widely developed for cancer research. This study used an intrabody against p65 subunit to prevent nuclear factor kappaB (NF-kappaB) transcriptional activity in glioma cells and to inhibit the expression of its target genes involved in the invasion and angiogenesis of human gliomas. EXPERIMENTAL DESIGN: A single-chain fragment of antibody variable region (scFv) against p65 was prepared using phage display technique. We then prepared an anti-p65 intrabody construct (pFv/nu) by cloning the scFv-encoding sequence into the mammalian nuclear-targeting vector, pCMV/myc/nuc. RESULTS: p65 expression in human glioma cells (U251 and] U87) transfected with pFv/nu was significantly decreased. We showed that NF-kappaB nuclear translocation and its DNA binding activity were blocked via intrabody transfection in electrophoretic mobility shift assays and the inhibition of NF-kappaB activity in nucleus resulted in the decreasing expression and bioactivity of matrix metalloproteinase-9, urokinase-type plasminogen activator receptor, urokinase-type plasminogen activator, and vascular endothelial growth factor. The intrabody transfected glioma cells showed a markedly lower level of invasion in Matrigel invasion assay. The capillary-like structure formation of endothelial cells was also repressed by coculture with the intrabody transfected glioma cells or exposure to their conditional medium. Intrabody transfection neither induced apoptosis nor altered cell proliferation in U251 and U87 cells as compared with the control vector pCMV/nu. After the injection of pFv/nu-transfected glioma cells, preestablished tumors were almost completely regressed when compared with mock, pCMV/nu, and pGFP/nu. CONCLUSION: Blocking NF-kappaB activity via the nuclear intrabody expression might be a potential approach for cancer therapy.

Sense p16 and antisense uPAR bicistronic construct inhibits angiogenesis and induces glioma cell death.

High-grade gliomas comprise the most malignant type of primary brain tumor and are relatively frequent in adults. Recent studies have indicated that the loss of p16, an inhibitor of CDK4, promotes the acquisition of malignant characteristics in gliomas. A correlation between overexpression of urokinase-type plasminogen activator receptor (uPAR) and glioblastoma invasion has also been established. Moreover, uPAR/integrin binding has been shown to initiate or potentiate integrin signaling through focal adhesion kinase and/or src kinases. Our previous studies demonstrated that downregulation of uPAR expression and restoration of p16 regress glioma growth in nude mice and downregulate alphavbeta3 integrin receptor expression. Here, we show the effect of a bicistronic construct on alphavbeta5 integrin receptor expression, angiogenesis and the biochemical pathway that causes glioma cell death. The U251 glioblastoma and a glioblastoma xenograft cell line transduced with a recombinant replication-defective adenovirus vector containing the cDNA of wild-type p16 and antisense RNA of uPAR significantly inhibited human mammary epithelial cell capillary formation and vascular endothelial growth factor (VEGF) expression. Inactivation of anti-apoptotic molecules such as Akt, PARP, activation of caspases and accumulation of heteroduplex chromosomal DNA in pre-G1 phase of the cell cycle was demonstrated by Western blotting, caspase activity assay and FACS analysis. Nuclear DNA fragmentation upon induction of apoptosis was scored using the TUNEL assay. Significant downregulation of alphavbeta5 integrin receptor expression was also confirmed by FACS analysis, immunoprecipitation and RT-PCR. Taken together, the results demonstrate that the sense p16 and anti-sense uPAR bicistronic construct significantly inhibits angiogenesis, induces apoptosis by deregulation of the PI3K-Akt pathway and downregulates alphavbeta5 integrin receptor expression.

RNAi-mediated abrogation of cathepsin B and MMP-9 gene expression in a malignant meningioma cell line leads to decreased tumor growth, invasion and angiogenesis.

Malignant meningiomas are highly aggressive and frequently recur after surgical resection of the tumor. Earlier studies have reported that the cysteine protease cathepsin B and the matrix metalloproteinase MMP-9 play important roles in tumor progression. In the present study, we made an attempt to evaluate the roles of these proteases in the malignant meningioma tumor microenvironment and determined the effectiveness of using single or bicistronic siRNA constructs for cathepsin B and MMP-9, in both in vitro and in vivo models. Transfection of a plasmid vector expressing double-stranded RNA for cathepsin B and MMP-9 significantly inhibited mRNA and protein levels of cathepsin B and MMP-9. The migration and invasion of meningioma cells were decreased after treatment with single or bicistronic siRNA constructs for cathepsin B and MMP-9 compared to controls and vector controls. Inhibition of angiogenesis was observed when the cells were transfected with single or bicistronic constructs for cathepsin B and MMP-9, when compared to controls or empty vector controls. Our study revealed that abrogation of cathepsin B and MMP-9 expression decreased the activation of major proteins involved in MAP kinase and PI3 kinase pathways indicating that targeting these proteases may hinder intracellular signaling and thus decrease cell survival and proliferation in malignant meningiomas. In addition to the in vitro evidence, we observed a significant regression of pre-established orthotopic tumors after treatment with RNAi plasmid vectors targeting cathepsin B and MMP-9. Furthermore, these observations demonstrate that the simultaneous RNAi-mediated targeting of cathepsin B and MMP-9 has potential application for the treatment of human meningiomas.

A computed tomography scan and anatomical cadaveric study of the pterygopalatine ganglion for use in Gamma Knife treatment of cluster headache.

OBJECT: Gamma Knife surgery has recently been used to treat patients with cluster headaches. Both the trigeminal nerve root and the pterygopalatine ganglion (PPG) have been targeted. However, there are no clear-cut anatomical landmarks on computed tomography (CT) scans or magnetic resonance images that accurately identify the PPG. Therefore, the authors performed microsurgical dissections on latex-injected cadaver heads to expose the PPG and correlated the findings with thin-slice axial CT scans obtained in the same heads to determine how best to target the PPG. METHODS: Three cadaver heads (five sides) previously injected with colored latex were dissected using skull base approaches and microsurgical techniques to identify the PPG and surrounding structures. Measurements were then made to different osseous anatomical landmarks such as the foramen rotundum, vidian canal, and so on. The PPG was marked with a radiopaque marker and thin-slice CT scans were obtained in the cadaver heads to develop some correlates that could be used to identify where the PPG is located on CT scans. RESULTS: The PPG was clearly identified in all specimens and had a mean diameter of 3.58 +/- 0.6 mm. The PPG was always located in the same plane (lateral and vertical) as the vidian canal and was located on average 2.7 +/- 0.3 mm from the end of the canal. The vidian canal was clearly identified on coronal CT scans and had a diameter of 3.05 mm. CONCLUSIONS: There was a clear and constant relationship between the PPG and vidian canal. The vidian canal is easily identified on coronal CT scans and can be used as a landmark to target the PPG with the Gamma Knife.

RNA interference-mediated simultaneous down-regulation of urokinase-type plasminogen activator receptor and cathepsin B induces caspase-8-mediated apoptosis in SNB19 human glioma cells.

The invasive character of gliomas depends on proteolytic cleavage of the surrounding extracellular matrix. Cathepsin B and urokinase-type plasminogen activator receptor (uPAR) together are known to be overexpressed in gliomas and, as such, are attractive targets for gene therapy. In the present study, we used plasmid constructs to induce the RNA interference (RNAi)-mediated down-regulation of uPAR and cathepsin B in SNB19 human glioma cells. We observed that the simultaneous down-regulation of uPAR and cathepsin B induces the up-regulation of proapoptotic genes and initiates a collapse in mitochondrial Deltapsi. Cathepsin B and uPAR down-regulated cells showed increases in the expression of activated caspase-8 and DFF40/caspase-activated DNase. Nuclear translocation of AIF and Fas ligand translocation to the cell membrane were also observed. Ki67 and X-linked inhibitor of apoptosis protein levels decreased, thereby indicating apoptosis. These results suggest the involvement of uPAR-cathepsin B complex on the cell surface and its role in maintaining the viability of SNB19 glioma cells. In conclusion, RNAi-mediated down-regulation of uPAR and cathepsin B initiates a partial extrinsic apoptotic cascade accompanied by the nuclear translocation of AIF. Our study shows the potential of RNAi-mediated down-regulation of uPAR and cathepsin B in developing new therapeutics for gliomas.

Predictive (subtle or overlooked) initial head CT findings in patients who develop delayed chronic subdural hematoma.

With the aging population, the incidence of chronic subdural hematoma (CSDH) is expected to rise. Once symptomatic the morbidity from CSDH is not insignificant. We studied patients who had a minor head injury and CT brain scan prior to developing CSDH to determine if there were any predictors on these scans for subsequent development of a CSDH. A retrospective review was performed on all patients operated for CSDH over a 3-year period and a review performed on those who had imaging studies at the time of a preceding minor head injury. Seven of 37 patients had CT scans prior to developing CSDH. All had evidence of small increases in CSF intensity on the side or sides of the subsequent CSDH. In conclusion, in those patients with a history of minor head injury prior to developing a CSDH, CT brain demonstrated small increases in cerebral spinal fluid (CSF) intensity on the side or sides of the subsequent CSDH. Recognizing this finding may be helpful in monitoring these patients or initiating medical therapy.

Down-regulation of uPAR and cathepsin B retards cofilin dephosphorylation.

Cathepsin B and uPAR play key roles in cancer cell migration and invasion. Here, we demonstrate that the simultaneous, siRNA-mediated down-regulation of uPAR and cathepsin B inhibits glioma cell migration and is accompanied by cytoskeletal condensation. We show that the dephosphorylation of cofilin is inhibited by the down-regulation of uPAR alone and, to a lesser extent, by the down-regulation of cathepsin B alone, and that the effect was much higher with the down-regulation of both molecules by pUC. Using FACS analysis and western blotting for the alphaVbeta3 integrin heterodimer, we determined that down-regulating uPAR subsequently causes the down-regulation of the alphaVbeta3 integrin heterodimer. As evidenced by western blot analysis of ERK1/2, pERK1/2, p38MAPK, p-p38MAPK, AKT, pAKT and PI3-k, the MEK and PI3-k pathways are inhibited. From cytoskeleton studies, we observed that the down-regulation of uPAR caused cytoskeletal condensation and that the simultaneous down-regulation of uPAR and cathepsin B was even more effective at inducing cytoskeletal condensation than uPAR alone. Our results demonstrate the relevance of uPAR in cytoskeletal dynamics and the potential of uPAR and cathepsin B as targets in the treatment of malignant gliomas.

RNAi-mediated downregulation of urokinase plasminogen activator and its receptor in human meningioma cells inhibits tumor invasion and growth.

In recent years, RNA interference (RNAi) has emerged as an effective method to target specific genes for silencing. Several groups are actively exploring the use of small interfering RNA (siRNA) for therapeutic applications to treat cancer. Our previous studies have demonstrated the inhibition of various proteases, including serine proteases, cysteine proteases and matrix metalloproteases, via RNA interference (RNAi) in gliomas. Similar to gliomas, malignant meningiomas also exhibit elevated protease levels in comparison to normal brain and benign meningiomas. Here, we used siRNA to simultaneously target urokinase plasminogen activator (uPA) and its receptor, uPAR. A human CMV promoter-driven mammalian expression vector (pU2) was used to produce hairpin double-stranded RNA (hp RNA) to target uPA and uPAR. As determined by Western blotting and fibrin zymography, pU2 effectively inhibited uPAR protein levels and uPA enzymatic activity in meningioma cells (IOMM-Lee). In vitro studies (Matrigel invasion and spheroid migration) revealed reduced meningioma cell invasion and migration. Intratumoral injections of the plasmid vector expressing siRNA for uPA and uPAR resulted in regression of pre-established, subcutaneous tumors in mice. In addition, in vivo studies of mice injected with pU2-transfected meningioma cells revealed inhibition of intracranial tumor formation. These findings suggest that siRNA can be used as a potent and specific therapeutic tool for the treatment of malignant meningiomas in humans.

Restoration of tissue factor pathway inhibitor inhibits invasion and tumor growth in vitro and in vivo in a malignant meningioma cell line.

Tissue factor pathway inhibitor 2 (TFPI-2) is a 32-kDa extracellular matrix-associated kunitz-type serine proteinase inhibitor. It is secreted by all vascular cells and plays a role in tumor invasion and metastasis, presumably by plasmin-mediated matrix remodeling. Previous studies have shown high expression of TFPI-2 by benign tumors and low or absent expression in highly malignant tumors. Malignant meningiomas constitute 10-15% of all meningiomas and our previous studies revealed loss of expression of TFPI-2 in malignant gliomas. To investigate the role of TFPI-2 in the invasiveness of malignant meningiomas, we stably transfected the human meningioma cell line, IOMM-Lee, with a vector capable of expressing a transcript complementary to the full length of TFPI-2 mRNA in a sense orientation. Restoration of TFPI-2 led to decreased invasiveness of transfected cells compared to parental and vector controls in Matrigel and spheroid assays and inhibition of angiogenesis in in vitro co-cultures with human umbilical vein endothelial cells (HUVEC) and in vivo dorsal skin assay studies. As assessed by Western blotting, we also observed increased expression of BAX, cytochrome c and caspase 3 as well as decreased expression of XIAP (X-linked inhibitor of apoptosis). Finally, TFPI-2 overexpression inhibited intracranial tumor formation in nude mice. Our data substantiate our previous observation that TFPI-2 plays an important role in tumor progression and has potential in anti-cancer therapy.

SPARC-induced migration of glioblastoma cell lines via uPA-uPAR signaling and activation of small GTPase RhoA.

Secreted protein acidic and rich in cysteine (SPARC) is highly expressed in human gliomas where it promotes invasion and delays tumor growth, both in vitro and in vivo. SPARC, which interacts at the cell surface, has an impact on intracellular signaling and downstream gene expression changes, which might account for some of its effects on invasion and growth. Additionally in vitro studies demonstrated that SPARC delays growth, increases attachment, and modulates migration of tumor cells in an extracellular matrix-specific and concentration-dependent manner. Because the signaling aspect of this migration is neither well understood nor characterized, we overexpressed SPARC in both the minimally-invasive U87 cell line and in the most aggressive invasive cell line, SNB19. We first performed RT-PCR analysis and observed an upregulation of uPA and its receptor, uPAR. We also observed increased expression levels of matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9). Western blot analysis confirmed these results, and the enzymatic activity of the metalloproteinases and uPA was further supported by zymography. Downstream of the uPA-uPAR interaction, upregulation of PI3-K occurred in cells overexpressing SPARC. Using GST-TRBD, we showed the upregulation of active GTP-bound RhoA, but neither Rac1 nor Cdc42 were activated. The inhibition of uPA and uPAR downregulated PI3-K activity and cell migration, as shown by matrigel invasion assay. A dorsal skin-fold chamber model revealed the high angiogenic activity of SPARC, though the proliferation of SPARC overexpressing cells was unaffected. Our results show that the small GTPase RhoA was a critical mediator of invasion or migration in the uPA-uPAR/PI3-K signaling pathway.