Julie A. Stephens

Pten in stromal fibroblasts suppresses mammary epithelial tumours

The tumour stroma is believed to contribute to some of the most malignant characteristics of epithelial tumours. However, signalling between stromal and tumour cells is complex and remains poorly understood. Here we show that the genetic inactivation of Pten in stromal fibroblasts of mouse mammary glands accelerated the initiation, progression and malignant transformation of mammary epithelial tumours. This was associated with the massive remodelling of the extracellular matrix (ECM), innate immune cell infiltration and increased angiogenesis. Loss of Pten in stromal fibroblasts led to increased expression, phosphorylation (T72) and recruitment of Ets2 to target promoters known to be involved in these processes. Remarkably, Ets2 inactivation in Pten stroma-deleted tumours ameliorated disruption of the tumour microenvironment and was sufficient to decrease tumour growth and progression. Global gene expression profiling of mammary stromal cells identified a Pten-specific signature that was highly represented in the tumour stroma of patients with breast cancer. These findings identify the Pten–Ets2 axis as a critical stroma-specific signalling pathway that suppresses mammary epithelial tumours.

Predicting PTEN mutations: an evaluation of Cowden syndrome and Bannayan–Riley–Ruvalcaba syndrome clinical features

Background Cowden syndrome (CS) is associated with benign hamartomatous lesions and risks for thyroid, breast and endometrial cancers. Bannayan–Riley–Ruvalcaba syndrome is an allelic disorder characterised by macrocephaly, intestinal polyps, lipomas, and pigmented penile macules. Diagnostic criteria for CS are based on the presence of a range of clinical features. However, prior data on the component clinical features have been based primarily on compilations of cases reported before development of consensus diagnostic criteria. Objective This study sought to determine the clinical features most predictive of a mutation in the largest single cohort of patients with clinical testing for PTEN mutations reported to date. Methods Molecular and clinical data were reviewed on 802 patients referred for PTEN analysis by a single laboratory. Results Deleterious mutations were found in 172 (21.4%) subjects. Among mutation carriers significant differences from previous reports were found for the frequencies of several clinical features, including macrocephaly, uterine fibroids, benign breast disease, and endometrial cancer. Logistic regression analyses indicated that female mutation carriers were best identified by the presence of macrocephaly, endometrial cancer, trichilemmomas, papillomatous papules, breast cancer, benign thyroid disease, and benign gastrointestinal (GI) lesions. For males, the most discriminating features were macrocephaly, lipomas, papillomatous papules, penile freckling, benign GI lesions, and benign thyroid disease. Age related differences were also identified. Conclusion The mutation frequency in patients meeting CS diagnostic criteria (34%) was significantly lower than previously reported, suggesting a need for reevaluation of these criteria. A mutation prediction model has been developed which can help identify patients appropriate for PTEN testing in clinical practice.

Combination immunotherapy of B-cell non-Hodgkin's lymphoma with rituximab and interleukin-2: a preclinical and phase I study.

Purpose: Cytokine-induced modulation of innate immunity is being explored to enhance the activity of monoclonal antibodies. Severe combined immunodeficient (SCID) mice engrafted with peripheral blood leukocytes (PBLs) from Epstein Barr virus-seropositive donors develop human B-cell non-Hodgkin’s lymphomas [B-NHLs (hu-PBL-SCID mouse model)]. We used this hu-PBL-SCID mouse model to study the synergism between interleukin (IL)-2 and rituximab. We also conducted a phase I trial of IL-2 and rituximab in relapsed B-NHL to study whether expansion of natural killer (NK) cells and enhanced cellular cytotoxicity could be safely accomplished in vivo. Experimental Design: Hu-PBL-SCID mice were treated with various schedules of rituximab and IL-2, with survival as the end point. Patients with relapsed B-NHL received rituximab (375 mg/m2 weekly × 4) followed by daily low-dose IL-2 (1 MIU/m2/day × 4 weeks) with pulses of intermediate-dose IL-2 (3–15 MIU/m2). Toxicity, NK cell numbers, and cellular cytotoxicity were measured. Results: In the hu-PBL-SCID mouse, the combination of rituximab and IL-2 showed greater activity against B-NHL than either agent alone. Treatment was most effective when IL-2 was given before rituximab. Twelve patients with heavily pretreated B-NHL entered the phase I trial. Toxicity was manageable, and responses were observed. NK cell expansion and enhanced cellular cytotoxicity against a B-cell lymphoma target were observed but did not correlate with response. Conclusions: The combination of IL-2 and rituximab is synergistic against B-NHL in the hu-PBL-SCID model. In the phase I trial, a sequential combination of rituximab and IL-2 was well tolerated and achieved biological end points. Responses were observed.

Innate Immune Dysfunction is Associated with Enhanced Disease Severity In Infants with Severe Respiratory Syncytial Virus Bronchiolitis

BACKGROUND Most patients with respiratory syncytial virus (RSV) bronchiolitis requiring admission to the pediatric intensive care unit (PICU) have no risk factors for severe disease. We sought to investigate the relationship between serum cytokine concentrations, innate immune responsiveness, and RSV disease severity. METHODS Previously healthy infants (median age, 2.6 months) with RSV bronchiolitis (PICU, n = 20; floor, n = 46) and healthy matched controls (n = 14) were enrolled, and blood samples were obtained within 24 hours of admission to measure plasma tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), interleukin 8 (IL-8), and interleukin 10 (IL-10) concentrations and, whole blood lipopolysaccharide-stimulated cytokine production capacity. RESULTS Plasma IL-6, IL-8, and IL-10 concentrations were comparable between PICU and floor patients, but higher than in healthy controls (P < .05). In contrast, TNF-α, IL-6, and IL-8 production capacity was significantly decreased in PICU compared with both floor patients and healthy controls. In adjusted analyses, only impaired TNF-α and IL-8 production capacity were associated with longer length of stay (P = .035) and greater disease severity scores (P = .001). CONCLUSIONS Infants with severe RSV bronchiolitis had increased plasma cytokine concentrations and yet impaired innate immunity cytokine production capacity, which predicted worse disease outcomes. Immune monitoring of otherwise healthy infants with RSV lower respiratory tract infection could help identify patients at risk for severe disease at the time of hospitalization.

Polymerase ɛ (POLE) mutations in endometrial cancer: Clinical outcomes and implications for Lynch syndrome testing

DNA polymerase ɛ (POLE) exonuclease domain mutations characterize a subtype of endometrial cancer (EC) with a markedly increased somatic mutational burden. POLE‐mutant tumors were described as a molecular subtype with improved progression‐free survival by The Cancer Genome Atlas. In this study, the frequency, spectrum, prognostic significance, and potential clinical application of POLE mutations were investigated in patients with endometrioid EC.

Specific tumor suppressor function for E2F2 in Myc-induced T cell lymphomagenesis

Deregulation of the Myc pathway and deregulation of the Rb pathway are two of the most common abnormalities in human malignancies. Recent in vitro experiments suggest a complex cross-regulatory relationship between Myc and Rb that is mediated through the control of E2F. To evaluate the functional connection between Myc and E2Fs in vivo, we used a bitransgenic mouse model of Myc-induced T cell lymphomagenesis and analyzed tumor progression in mice deficient for E2f1, E2f2, or E2f3. Whereas the targeted inactivation of E2f1 or E2f3 had no significant effect on tumor progression, loss of E2f2 accelerated lymphomagenesis. Interestingly, loss of a single copy of E2f2 also accelerated tumorigenesis, albeit to a lesser extent, suggesting a haploinsufficient function for this locus. The combined ablation of E2f1 or E2f3, along with E2f2, did not further accelerate tumorigenesis. Myc-overexpressing T cells were more resistant to apoptosis in the absence of E2f2, and the reintroduction of E2F2 into these tumor cells resulted in an increase of apoptosis and inhibition of tumorigenesis. These results identify the E2f2 locus as a tumor suppressor through its ability to modulate apoptosis.

Biomechanical Analysis of Distal Biceps Tendon Repair Methods

Background The 1-incision and 2-incision techniques are commonly used methods to repair a distal biceps rupture, and they differ in the location of reinsertion of tendon into bone. Hypothesis The native distal biceps brachii tendon inserts on the posterior-ulnar aspect of the bicipital tuberosity, which functions as a cam, increasing the tendons moment arm during its principal action of forearm supination. Repair of the distal biceps tendon to the anterior aspect of the tuberosity compromises forearm supination due to absence of the bicipital tuberositys cam effect. Study Design Controlled laboratory study. Methods Eleven matched pairs of fresh-frozen cadaveric upper extremities were prepared for repair of the distal biceps tendon using either anterior or posterior reattachment with transosseous suture fixation. Specimens were tested on a materials testing machine with intact distal biceps insertion and after repair. A load cell at the distal radial-ulnar joint measured resultant elbow flexion and forearm supination torque produced by 100-N force applied to the proximal aspect of the tendon. Results Although there was a trend (P = .104) toward loss of supination torque with the anterior reconstruction method, no significant differences in torque (0.80 vs 0.89 N·m) or flexion force (11.87 vs 12.07 N) were found between the anterior and posterior reconstruction techniques. Conclusion There is no statistically significant difference in flexion force or supination torque between the anterior and posterior reconstruction techniques. Clinical Relevance This study supports existing limited clinical data suggesting no functional differences exist between 2 common repair methods. Further biomechanical and clinical investigations directly comparing the results of distal biceps tendon repairs made to the anterior aspect versus the posterior aspect of the tuberosity are necessary to definitely determine if differences exist in resultant elbow flexion and forearm supination functions.

DISEASE CONTROL, SURVIVAL, AND FUNCTIONAL OUTCOME AFTER MULTIMODAL TREATMENT FOR ADVANCED-STAGE TONGUE BASE CANCER

Surgical resection and postoperative radiation for advanced‐stage malignancies of the oral cavity, oropharynx, and hypopharynx result in a dismal overall survival of 38%. Patients with carcinoma of the tongue base frequently have advanced disease at the time of presentation, and combined‐modality therapy is usually required to achieve cure. Because of the poor survival rates with advanced malignancies with standard therapy, new and innovative approaches continue to be developed in an attempt to have a greater impact on disease control, patient survival, and functional outcome after therapy. This study examines functional outcome, survival, and disease control in patients receiving an intensified treatment regimen with concomitant chemoradiotherapy, surgery, and intraoperative radiotherapy for previously untreated, resectable, stage III and IV squamous cell carcinoma (SCC) of the tongue base.

Allele-specific tumor spectrum in Pten knockin mice

Germline mutations in the tumor suppressor gene PTEN (phosphatase and tensin homology deleted on chromosome 10) cause Cowden and Bannayan–Riley–Ruvalcaba (BRR) syndromes, two dominantly inherited disorders characterized by mental retardation, multiple hamartomas, and variable cancer risk. Here, we modeled three sentinel mutant alleles of PTEN identified in patients with Cowden syndrome and show that the nonsense Pten∆4–5 and missense PtenC124R and PtenG129E alleles lacking lipid phosphatase activity cause similar developmental abnormalities but distinct tumor spectra with varying severity and age of onset. Allele-specific differences may be accounted for by loss of function for Pten∆4–5, hypomorphic function for PtenC124R, and gain of function for PtenG129E. These data demonstrate that the variable tumor phenotypes observed in patients with Cowden and BRR syndromes can be attributed to specific mutations in PTEN that alter protein function through distinct mechanisms.

Mismatch repair status and outcomes after adjuvant therapy in patients with surgically staged endometrial cancer.

OBJECTIVES To determine whether DNA mismatch repair (MMR) modifies the response to chemotherapy or radiotherapy in patients with endometrial cancer. METHODS Immunohistochemistry (IHC) for the DNA MMR proteins MLH1, MSH2, MSH6, and PMS2 was performed on a tissue microarray of specimens of primary endometrial cancer. MMR deficiency was defined as lack of expression of one or more proteins. Expression of all proteins classified a tumor as having an intact MMR system. Recurrence rates were calculated for women treated with platinum-based chemotherapy or pelvic external beam radiation. Comparisons were made using the log-rank test. Multiple comparisons were controlled for by utilizing the Bonferroni correction method. RESULTS Four hundred seventy-seven cases of endometrial cancer were evaluated on a tissue microarray (TMA). One hundred fifty-eight patients (41%) received chemotherapy. Sixty-six patients (17%) received pelvic teletherapy. Overall and progression-free survival were not different between patients whose tumors had intact MMR and those with defective MMR when stratified by adjuvant treatment with radiation or chemotherapy. Subgroup analyses stratified by histology (non-endometrioid versus endometrioid) and stage did show significant survival differences. There was a significant increase in overall (p=0.003) and progression-free (p=0.004) survival in those with MMR-deficient, non-endometrioid tumors treated with teletherapy compared to those with an intact MMR system. Improved progression-free survival was noted in patients with intact MMR with stage III/IV disease treated with adjuvant chemotherapy (p=0.031). CONCLUSIONS Subgroups of patients with non-endometrioid endometrial cancer and defective MMR may have improved survival after adjuvant radiotherapy. Patients with advanced stage endometrial cancer and defects in mismatch repair may receive less benefit from adjuvant chemotherapy.