Activation of PDGFR and EGFR promotes the acquisition of a stem cell-like phenotype in schwannomas.

OBJECTIVES: Vestibular schwannomas (VS) are benign tumors that arise from unregulated growth of Schwann cells. Both benign and malignant tumors are believed to contain tumor stem cells that are hypothesized to originate from dysregulation of tumor suppressors and oncogenes. We aimed to determine if schwannoma cells express stem cell genes and markers and if activation of the proto-oncogenes epidermal growth factor receptor and platelet-derived growth factor receptor would regulate the stem cell properties of these cells. METHODS: Immunohistochemical staining was used to determine the expression of stem cell genes in archived VS tissue, immunofluorescence was used to investigate the expression in cell lines, and Western blot analysis was used to measure PDGFR expression in vestibular schwannoma tissue. Upon activation of PDGFR or EGFR in schwannoma cell lines using specific ligands, flow cytometry was used to quantify the side population (SP), stem cell genes were measured using quantitative PCR, and tumorsphere-forming ability was determined. RESULTS: Stem cell genes are expressed in vestibular schwannoma tissue and schwannoma cell lines. Activation of both EGFR and PDGFR resulted in increase in the induction of the expression of the stem cell genes Oct-4 and Nanog and marked increase in tumorsphere-forming ability, but only PDGFR activation resulted in an increase in the side population in JS1 cells. CONCLUSION: Dysregulation of EGFR and PDGFR promotes the acquisition of a stem cell-like phenotype in schwannnoma cells that may be critical in vestibular schwannoma tumorigenesis.

A randomized controlled trial of cognitive-behavior therapy for tinnitus.

This study is a randomized, waitlist-controlled trial testing the effect of a brief, "manualized" cognitive-behavioral group therapy on distress associated with tinnitus, quality of well-being, psychological distress including depression, and internal focus. Cognitive-behavioral therapy (CBT) included training in activity planning, relaxation training and, primarily, cognitive restructuring. Sixty-five participants were recruited, and 41 completed treatment. Participants were randomly assigned to receive 8 weeks of manualized group CBT either immediately or after an 8-week waiting period. Participants completed outcome measures at the time of their random assignment and at 8, 16, and 52 weeks later. Repeated-measure analysis of covariance revealed significant group-by-time interactions on measures of tinnitus distress and depression, indicating that CBT led to greater improvement in those symptoms. The current results suggest that CBT, applied in a group format using a manual, can reduce the negative emotional distress, including depression, associated with tinnitus.

Randomized placebo-controlled trial of a selective serotonin reuptake inhibitor in the treatment of nondepressed tinnitus subjects.

OBJECTIVE: To assess the efficacy of a selective serotonin reuptake inhibitor (paroxetine) for relief of tinnitus. DESIGN: One hundred twenty tinnitus sufferers participated in a randomized double-blind placebo-controlled trial. Paroxetine or placebo was increased to a maximally tolerated dose (up to 50 mg/day), and patients were treated for a total of 31 days at the maximal dose. METHODS: Patients with chronic tinnitus were recruited from our university-based specialty clinic by referral from otolaryngologists and audiologists in the local community and by advertisement. Patients with psychotic or substance use disorders or suicidal ideation were excluded, as were those using psychoactive medications (this resulted in only 1 subject with major depression in the study) or any other medications that interact with paroxetine and those with inability to hear at one's tinnitus sensation level. Fifty-eight percent of patients were male, 92% were Caucasian, and the average age was 57. OUTCOMES MEASURES: Tinnitus matching, the Tinnitus Handicap Questionnaire, the question: How severe (bothered, aggravating) is your tinnitus? Quality of Well-Being and other psychological questionnaires. RESULTS: Paroxetine was not statistically superior to placebo on the following tinnitus measures (tinnitus matching, 5- or 10-db drop, Tinnitus Handicap Questionnaire, quality of well-being measures, how severe, how bothered, positive change). There was a significant improvement in the single item question, How aggravating is your tinnitus? for those in the paroxetine group compared with the placebo group. CONCLUSIONS: These results suggest that the majority of individuals in this study did not benefit from paroxetine in a consistent fashion. Further work remains to be done to determine if subgroups of patients (e.g., those who tolerate higher doses, those who are depressed) may benefit.