Myosin 1e promotes breast cancer malignancy by enhancing tumor cell proliferation and stimulating tumor cell de-differentiation.

Despite advancing therapies, thousands of women die every year of breast cancer. Myosins, actin-dependent molecular motors, are likely to contribute to tumor formation and metastasis via their effects on cell adhesion and migration and may provide promising new targets for cancer therapies. Using the MMTV-PyMT murine model of breast cancer, we identified Myosin 1e (MYO1E) as a novel tumor promoter. Tumor latency in mice lacking MYO1E was significantly increased, and tumors formed in the absence of MYO1E displayed unusual papillary morphology, with well-differentiated layers of epithelial cells covering fibrovascular cores, rather than solid sheets of tumor cells typically observed in this cancer model. These tumors were reminiscent of papillary breast cancer in humans that is typically non-invasive and often cured by tumor excision. MYO1E-null tumors exhibited decreased expression of the markers of cell proliferation, which was recapitulated in primary tumor cells derived from MYO1E-null mice. In agreement with our findings, meta-analysis of patient survival data indicated that MYO1E expression level was associated with reduced recurrence-free survival in basal-like breast cancer. Overall, our data suggests that MYO1E contributes to breast tumor malignancy and regulates the differentiation and proliferation state of breast tumor cells.

Reduced B lymphoid kinase (Blk) expression enhances proinflammatory cytokine production and induces nephrosis in C57BL/6-lpr/lpr mice.

BLK, which encodes B lymphoid kinase, was recently identified in genome wide association studies as a susceptibility gene for systemic lupus erythematosus (SLE), and risk alleles mapping to the BLK locus result in reduced gene expression. To determine whether BLK is indeed a bona fide susceptibility gene, we developed an experimental mouse model, namely the Blk+/-.lpr/lpr (Blk+/-.lpr) mouse, in which Blk expression levels are reduced to levels comparable to those in individuals carrying a risk allele. Here, we report that Blk is expressed not only in B cells, but also in IL-17-producing γδ and DN αß T cells and in plasmacytoid dendritic cells (pDCs). Moreover, we found that solely reducing Blk expression in C57BL/6-lpr/lpr mice enhanced proinflammatory cytokine production and accelerated the onset of lymphoproliferation, proteinuria, and kidney disease. Together, these findings suggest that BLK risk alleles confer susceptibility to SLE through the dysregulation of a proinflammatory cytokine network.

Podocyte-specific knockout of myosin 1e disrupts glomerular filtration.

Myosin 1e (myo1e) is an actin-dependent molecular motor that plays an important role in kidney functions. Complete knockout of myo1e in mice and Myo1E mutations in humans are associated with nephrotic syndrome and focal segmental glomerulosclerosis. In this paper, we tested the hypothesis that myo1e is necessary for normal functions of glomerular visceral epithelial cells (podocytes) using podocyte-targeted knockout of myo1e. Myo1e was selectively knocked out in podocytes using Cre-mediated recombination controlled by the podocin promoter. Myo1e loss from podocytes resulted in proteinuria, podocyte foot process effacement, and glomerular basement membrane disorganization. Our findings indicate that myo1e expression in podocytes is necessary for normal glomerular filtration and that podocyte defects are likely to represent the primary pathway leading to glomerular disease associated with Myo1E mutations.

Prognostic significance of mucin and p53 expression in stage IB non-small cell lung cancer: a laboratory companion study to CALGB 9633.

INTRODUCTION: Cancer and Leukemia Group B 9633 was a phase III trial that randomized patients with stage IB non-small cell lung cancer to observation or four cycles of carboplatin and paclitaxel. A statistically significant effect in favor of adjuvant chemotherapy was seen for disease-free survival (DFS) and overall survival (OS) in the subgroup of patients with tumors > or =4 cm. A laboratory companion study was conducted to see whether molecular and clinical factors could provide additional prognostic information. METHODS: Formalin-fixed, paraffin-embedded blocks were obtained for 250 of the 344 patients enrolled. Immunohistochemical staining for bcl-2, p53, blood group antigen A, and mucin was correlated with DFS and OS. RESULTS: The prevalence of the markers was bcl-2, 17%; p53, 47%; blood group antigen A, 25%; and mucin, 45%. Univariate analysis for DFS showed a statistically significant effect for the presence of mucin (p = 0.0005) and p53 (p = 0.05) and for OS showed a significant effect for mucin (p = 0.0005). In the multivariate Cox model, there was a statistically significant association between shorter DFS and presence of mucin (p = 0.002; hazard ratio [HR] 2.05) and p53 (p = 0.003; HR 1.95) and between shorter OS and presence of mucin (p = 0.004; HR 2.03) and p53 (p = 0.0005; HR 2.30). Of the clinical factors, male gender and larger tumor volume were also significant adverse prognostic factors (p 0.05). CONCLUSIONS: A statistically significant association between shorter DFS and OS was seen for the patients with p53 protein expression, mucin expression, male gender, and larger tumors in this cohort of patients with stage IB non-small cell lung cancer treated on Cancer and Leukemia Group B 9633.

The predictive value of neuroendocrine markers and p53 for response to chemotherapy and survival in patients with advanced non-small cell lung cancer.

BACKGROUND: A minority of patients (30-40%) with advanced non-small cell lung cancer (NSCLC) have objective responses to chemotherapy. Therefore, defining molecular features that determine resistance or response to chemotherapy would have important implications in this disease. Several studies have suggested that patients whose tumors have neuroendocrine features may be more responsive to chemotherapy. In addition, increased expression of p53 may play a role in chemotherapy resistance in patients with NSCLC. METHODS: The objective of this study was to analyze retrospectively, the correlation between marker expression and response to chemotherapy and survival using immunohistochemistry for neuroendocrine markers and p53. Ninety patients with unresectable stage III or IV NSCLC, treated with platinum based combination chemotherapy were evaluated. The pathological specimens were obtained prior to chemotherapy. RESULTS: There was no statistically significant correlation between any individual marker and response to chemotherapy. However, patients with tumors with increased expression of p53 were more likely to have progressive disease following chemotherapy (P=0.02). Similarly, patients with tumors lacking neuroendocrine expression and with increased expression of p53 were more likely to have progressive disease when compared to patients with tumors with normal p53 expression and neuroendocrine differentiation (P=0.03). Normal expression of p53 along with the presence of neuroendocrine differentiation was a favorable factor for both survival (P=0.05) and time to disease progression (P=0.04) in the multivariate analysis. CONCLUSION: The presence of neuroendocrine markers alone was not predictive of response to chemotherapy and did not impact on the survival of this group of patients with advanced stage NSCLC. The normal expression of p53 together with neuroendocrine differentiation seems to impact favorably on overall survival time and time to disease progression without significant improvement in response to chemotherapy.