We have studied the ability of c-myc and bd-2 oncogenes to modulate p53 function. Our studies show that coincident expression ofhuman BcI-2 protein with p53 prolongs survival of murine erythroleukemia cells. This effect was assodated with a loss of the G, specificity of p53-mediated cell cycle arrest. Furthermore, we found that the c-myc and bcl-2 genes cooperate to inhibit p53 functions. Coexpression of bd-2 and c-myc can totally overcome p53-induced apoptosis and cell cycle arrest by altering the subcellular trafficking of p53 during the cell cycle: the p53 remains in the cytoplasm of the cotransfected cells during a critical period in G1. This finding suggests a mechanism by which normal hematopoletic progenitors can survive and proliferate despite p53 expression and by which the inappropriate expression of bcl-2 and c-myc can cooperate in transformation.

A temperature-sensitive mutant of murine p53 (p53va-135) dimethyl sulfoxide (DMSO) (19). We and others have previously shown that constitutive expression of either c-myc or c-myb prevents MEL cell differentiation (6,7,12,24,42), and expression of c-myb late in the process of differentiation is sufficient to block terminal differentiation (8,34). In many MEL cell lines, there is a lack of expression of the p53 (reviewed in reference 27) tumor suppressor gene or expression of a mutant p53 protein (29, 41). Furthermore, wild-type p53 could not be stably expressed by a p53-negative MEL cell line (22).Myeloid leukemic cell lines frequently fail to express p53, in contrast to lymphoid leukemic cell lines, which characteristically overexpress p53 (9,26,43). However, p53 is often detectable in primary human myeloid leukemic blasts, though the level of expression is low (23,47). p53 expression is also seen in normal human blast cells and increases with maturation (45). The myeloid leukemia cell line ML 1, which has wild-type p53 genes, lacks expression during logarithmic growth but shows increased expression with induced differentiation (23

Mesenchymal Stem Cells (MSCs) migrate specifically to tumors in vivo, and coupled with their capacity to bypass immune surveillance, are attractive vehicles for tumor-targeted delivery of therapeutic agents. This study aimed to introduce MSC-mediated expression of the sodium iodide symporter (NIS) for imaging and therapy of breast cancer. Tumor bearing animals received an intravenous or intratumoral injection of NIS expressing MSCs (MSC-NIS), followed by 99mTcO4- imaging 3-14Days (D) later using a BazookaSPECT γ-camera. Tissue was harvested for analysis of hNIS expression by RQPCR. Therapy animals received an intraperitoneal injection of 131I or saline 14D following injection of MSC-NIS, and tumor volume was monitored for 8 weeks. BazookaSPECT imaging following injection of MSC-NIS revealed an image of animal intestines and chest area at D3, with a weak tumor image also visible. By D14, the tumor was visible with a significant reduction in radionuclide accumulation in non-target tissue observed. hNIS gene expression was detected in the intestines, heart, lungs and tumor at early timepoints but later depleted in non-target tissues and persisted at the tumor site. Based on imaging/biodistribution data, animals received a therapeutic dose of 131I 14D following MSC-NIS injection. This resulted in a significant reduction in tumor growth (Mean ± SEM, 236 ± 62mm3 versus 665 ± 204 mm3 in controls). The ability to noninvasively track MSC migration and transgene expression in real time prior to therapy is a major advantage to this strategy. This promising data supports the feasibility of this approach as a novel therapy for breast cancer.

MicroRNAs are small non-coding RNA molecules that control gene expression post-transcriptionally, and are known to be altered in many diseases including breast cancer. The aim of this study was to determine the relevance of miR-379 in breast cancer. miR-379 expression was quantified in clinical samples including tissues from breast cancer patients (n=103), healthy controls (n=30) and patients with benign breast disease (n=35). The level of miR-379 and its putative target Cyclin B1 were investigated on all breast tissue specimens by RQ-PCR. Potential relationships with gene expression and patient clinicopathological details were also determined. The effect of miR-379 on Cyclin B1 protein expression and function was investigated using western blot, immunohistochemistry and proliferation assays respectively. Finally, the levels of circulating miR-379 were determined in whole blood from patients with breast cancer (n=40) and healthy controls (n=34). The level of miR-379 expression was significantly decreased in breast cancer (Mean(SEM) 1.9 (0.09) Log10 Relative Quantity (RQ)) compared to normal breast tissues (2.6 (0.16) Log10 RQ, p<0.01). miR-379 was also found to decrease significantly with increasing tumour stage. A significant negative correlation was determined between miR-379 and Cyclin B1 (r=-0.31, p<0.001). Functional assays revealed reduced proliferation (p<0.05) and decreased Cyclin B1 protein levels following transfection of breast cancer cells with miR-379. Circulating miR-379 was not significantly dysregulated in patients with breast cancer compared to healthy controls (p=0.42). This data presents miR-379 as a novel regulator of Cyclin B1 expression, with significant loss of the miRNA observed in breast tumours.

This purified recombinant rat alpha 3(IV)NC1, which is both antigenic and nephritogenic, will be of value in analysing autoimmune responses in experimental anti-GBM disease.