The Cdc42/Rac1 regulator CdGAP is a novel E-cadherin transcriptional co-repressor with Zeb2 in breast cancer.

The loss of E-cadherin causes dysfunction of the cell-cell junction machinery, which is an initial step in epithelial-to-mesenchymal transition (EMT), facilitating cancer cell invasion and the formation of metastases. A set of transcriptional repressors of E-cadherin (CDH1) gene expression, including Snail1, Snail2 and Zeb2 mediate E-cadherin downregulation in breast cancer. However, the molecular mechanisms underlying the control of E-cadherin expression in breast cancer progression remain largely unknown. Here, by using global gene expression approaches, we uncover a novel function for Cdc42 GTPase-activating protein (CdGAP) in the regulation of expression of genes involved in EMT. We found that CdGAP used its proline-rich domain to form a functional complex with Zeb2 to mediate the repression of E-cadherin expression in ErbB2-transformed breast cancer cells. Conversely, knockdown of CdGAP expression led to a decrease of the transcriptional repressors Snail1 and Zeb2, and this correlated with an increase in E-cadherin levels, restoration of cell-cell junctions, and epithelial-like morphological changes. In vivo, loss of CdGAP in ErbB2-transformed breast cancer cells impaired tumor growth and suppressed metastasis to lungs. Finally, CdGAP was highly expressed in basal-type breast cancer cells, and its strong expression correlated with poor prognosis in breast cancer patients. Together, these data support a previously unknown nuclear function for CdGAP where it cooperates in a GAP-independent manner with transcriptional repressors to function as a critical modulator of breast cancer through repression of E-cadherin transcription. Targeting Zeb2-CdGAP interactions may represent novel therapeutic opportunities for breast cancer treatment.

The evaluation of tumor-infiltrating lymphocytes (TILs) in breast cancer: recommendations by an International TILs Working Group 2014.

BACKGROUND: The morphological evaluation of tumor-infiltrating lymphocytes (TILs) in breast cancer (BC) is gaining momentum as evidence strengthens for the clinical relevance of this immunological biomarker. Accumulating evidence suggests that the extent of lymphocytic infiltration in tumor tissue can be assessed as a major parameter by evaluation of hematoxylin and eosin (H&E)-stained tumor sections. TILs have been shown to provide prognostic and potentially predictive value, particularly in triple-negative and human epidermal growth factor receptor 2-overexpressing BC. DESIGN: A standardized methodology for evaluating TILs is now needed as a prerequisite for integrating this parameter in standard histopathological practice, in a research setting as well as in clinical trials. This article reviews current data on the clinical validity and utility of TILs in BC in an effort to foster better knowledge and insight in this rapidly evolving field, and to develop a standardized methodology for visual assessment on H&E sections, acknowledging the future potential of molecular/multiplexed approaches. CONCLUSIONS: The methodology provided is sufficiently detailed to offer a uniformly applied, pragmatic starting point and improve consistency and reproducibility in the measurement of TILs for future studies.

Antimetabolic activity of L-ascorbic acid in human and animal tumors.

1. The effect of high concentrations of L-ascorbic acid on the growth of some human and animal transformed and non-transformed cell lines has been investigated. Directly implemented into culture of transformed cell lines it decreased [3H]thymidine, [3H]uridine and [3H]leucine incorporation into cells. Vitamin C inhibited DNA synthesis by transformed cells 3-4 times more efficiently than by normal cells. 2. In vivo treatment of athymic nude mice bearing human mammary carcinoma with 500 mg/kg L-ascorbic acid for the first 15 days markedly inhibited the growth of tumor cells. 3. As determined by alkaline elution, both DNA strand breaks and DNA cross links were observed in mammary carcinoma cells treated with vitamin C. DNA-DNA and DNA-protein cross links in cells treated with L-ascorbic acid were revealed by the proteinase K assay. Removal of vitamin C caused an immediate onset of spontaneous repair of single or double stranded DNA breaks. If, however, vitamin was reintroduced into cell culture, this spontaneous repair was reversed. 4. Our results indicate an antimetabolic activity of L-ascorbic acid in human and animal transformed cells, probably due to lethal damages in DNA.

Reversal of human myeloid leukemia cells into normal granulocytes and macrophages: activity and intracellular distribution of catalase.

The activity and intracellular distribution of catalase was studied in culture human myeloid leukemia cells before and after induction of differentiation with tunicamycin. Activity of catalase was increased 5-fold in acute myeloid leukemia cells (AML) and 3-fold in chronic myeloid leukemia cells in comparison with normal granulocytes. Tunicamycin induced differentiation of HL-60 line and primary AML line characterized by increase in phagocytic cells and changes to resemble mature myeloid cells. Fc receptors were also induced in cells after tunicamycin treatment. Induction of differentiation with tunicamycin decreased high activity of catalase in cultured leukemic cells. The results of digitonin titration experiments showed that in control granulocytes and differentiated leukemic cells most of the catalase activity is present in subcellular particles distinct from mitochondria or lysosomes. In contrast, the catalase activity in undifferentiated cells is present in the same compartment as the other cytosolic markers.