Tax-interacting protein 1 coordinates the spatiotemporal activation of Rho GTPases and regulates the infiltrative growth of human glioblastoma

PDZ domains represent one group of the major structural units that mediate protein interactions in intercellular contact, signal transduction and assembly of biological machineries. TIP-1 protein is composed of a single PDZ domain that distinguishes TIP-1 from other PDZ domain proteins that more often contain multiple protein domains and function as scaffolds for protein complex assembly. However, the biological functions of TIP-1, especially in cell transformation and tumor progression, are still controversial as observed in a variety of cell types. In this study, we have identified ARHGEF7, a guanine nucleotide exchange factor (GEF) for Rho GTPases, as one novel TIP-1 interacting protein in human glioblastoma cells. We found that the presence of TIP-1 protein is essential to the intracellular redistribution of ARHGEF7 and rhotekin, one Rho effector, and the spatiotemporally coordinated activation of Rho GTPases (RhoA, Cdc42 and Rac1) in migrating glioblastoma cells. TIP-1 knockdown resulted in both aberrant localization of ARHGEF7 and rhotekin, as well as abnormal activation of Rho GTPases that was accompanied with impaired motility of glioblastoma cells. Furthermore, TIP-1 knockdown suppressed tumor cell dispersal in orthotopic glioblastoma murine models. We also observed high levels of TIP-1 expression in human glioblastoma specimens, and the elevated TIP-1 levels are associated with advanced staging and poor prognosis in glioma patients. Although more studies are needed to further dissect the mechanism(s) by which TIP-1 modulates the intracellular redistribution and activation of Rho GTPases, this study suggests that TIP-1 holds potential as both a prognostic biomarker and a therapeutic target of malignant gliomas.

TNF-alpha and IL-1 upregulate membrane-bound and soluble E-selectin through a common pathway

BACKGROUND

Endothelial cell adhesion molecules such as E-selectin promote the capture of neutrophils (PMN) in the microcirculation and initiate the inflammatory response. In contrast, when "shed" into the microcirculation, soluble E-selectin can bind PMN in the blood stream, reducing the number available for adhesion to injured tissue. These experiments were designed to better characterize the molecular response to cytokines and the balance between cell surface (bound) and soluble (unbound) E-selectin.

METHODS

Cultured human umbilical veins, exposed to human recombinant TNF-alpha or IL-1 (10 pg/ml), were analyzed for E-selectin mRNA induction (Northern blot), E-selectin cell surface expression (flow cytometry), and sE-selectin release (ELISA). Transcriptional regulation was analyzed via Raf kinase dominant negative gene transfection.

RESULTS

E-selectin mRNA expression was markedly increased at 2 h and sustained through 8 h. No further induction was noted at 12 h. Upregulation of cell surface E-selectin was noted (mean fluorescence) as early as 2 h for TNF-alpha (baseline, 12.28 +/- 1.32; TNF-alpha, 23.03 +/- 1.81) or 4 h for IL-1 (baseline, 12.28 +/- 1.32; IL-1, 70.00 +/- 3.04) with maximum expression at 6 h (TNF-alpha, 118.8+/-15; IL-1, 94.11 +/- 9. 34). Expression returned to baseline levels by 24 h. Soluble E-selectin (ng/ml) assays demonstrated later increases beginning at 12 h (TNF-alpha, 0.313 +/- 0.077; IL-1, 0.159 +/- 0.075) and continuing through 24 h (TNF-alpha, 0.340 +/- 0.062; IL-1, 0.157 +/- 0.030). Transfection of endothelial cells with Raf kinase 301 dominant negative gene resulted in proportionate decreases in the peak expression in both surface (bound) E-selectin (TNF-alpha, 51. 7%; IL-1, 29.6%) and sE-selectin (TNF-alpha, 49.2%; IL-1, 34.5%).

CONCLUSION

The temporal sequence of late decreases in cell surface E-selectin accompanied by increases in soluble E-selectin indicates that the source of E-selectin in the microcirculation is shed receptors rather than synthesis of a different type of receptor. Enhancement of such "shedding" may decrease PMN adhesion to injured tissue and have therapeutic potential.

High dose chemotherapy and stem cell rescue for aggressive non-Hodgkin's lymphoma: pattern of failure and implications for involved-field radiotherapy

PURPOSE

To evaluate the pattern of failure and outcome of patients with aggressive non-Hodgkin's lymphoma (NHL) undergoing high-dose chemotherapy (HDCT) and autologous stem cell rescue (SCR) with an emphasis on the role of adjuvant involved-field radiotherapy (IFRT).

METHOD AND MATERIALS

Fifty-three adult patients with aggressive NHL (46 intermediate-and 7 high-grade) underwent HDCT with SCR. All patients underwent induction chemotherapy prior to high dose intensification. Seven (13.2%) received IFRT to 10 disease sites either prior to or following HDCT. Indication included symptomatic or bulky disease, persistent disease, or to consolidate a complete response (CR). Sites of relapse were designated as old (involved prior to HDCT) or new (previously uninvolved). Median followup was 20.1 months (range, 1.2-69.3 months).

RESULTS

The 4-year actuarial progression-free (PFS) and cause-specific (CSS) survivals of the entire group were 30.0 and 50.2%, respectively. Excluding toxic deaths, 24 patients (52.2%) relapsed. Sixteen (34.7%) failed in old and 15 (32.6%) in new sites. Patients treated with IFRT had a lower rate of relapse in old sites (0 vs. 41%) (p = 0.04) than patients treated with HDCT alone. Of the 141 sites present prior to induction, 127 (90.1%) were amenable to IFRT. Excluding irradiated sites, the overall 4-year local control (LC) of all amenable sites was 61.1%. Amenable sites failing to achieve a CR to induction had a poorer LC (32.0 vs. 95.1%) (p < 0.0001) than sites in CR. The 4-year LC of sites failing to achieve a CR to HDCT was 29.4%. Adjuvant IFRT improved the 4-year LC of all sites (100 vs. 61.1%) (p = 0.05), persistent sites following induction (100 vs. 32.0%) (p = 0.01) and persistent sites following HDCT (100 vs. 29.4%) (p = 0.01). Adjuvant IFRT was not associated with any untoward acute or late toxicity.

CONCLUSIONS

The predominant site of relapse in patients with aggressive NHL undergoing HDCT and SCR is in sites of disease present prior to HDCT. However, the risk of relapse of prior disease sites varies greatly depending upon their response to chemotherapy. Sites at greatest risk are those failing to achieve a CR to induction regardless of their response to HDCT. IFRT is capable of reducing the high risk of relapse in these sites, the majority of which are amenable to IFRT. These results demonstrate a rationale for and possible benefit to IFRT in patients with aggressive NHL undergoing HDCT and SCR.

A randomized, double-blind trial of parenteral low dose versus high dose interferon-beta in combination with cryotherapy for treatment of condyloma acuminatum

Forty-nine subjects were enrolled in a study comparing two dosages of parenterally administered interferon (IFN)-beta in combination with cryotherapy for the treatment of anogenital warts. Subjects were randomized to receive subcutaneous injections of either 2 x 10(6) or 4 x 10(6) IU/m2 of IFN-beta (Biogen) three times a week for a total of 6 weeks. Cryotherapy was administered concomitantly by aerosolization of liquid nitrogen at 10-day intervals. Systemic side- effects were modest in intensity and included fever, chills, myalgia, and headaches (flu-like symptoms). During the first 2 weeks of therapy, they were more common in the high dose group than in the low dose group (P = 0.02). Using survival analysis, there was no significant difference between the two groups in rates of resolution of warts present at baseline (P = 0.62). However, the rate of new lesion formation during the study was significantly lower in the high dose group (P = 0.04).