BRCA1 regulation on ß-hCG: a mechanism for tumorigenicity in BRCA1 defective breast cancer.

Human chorionic gonadotropin ß (ß-hCG) has been implicated in breast tumorigenesis. However, the role of this hormone is highly controversial as certain studies suggest it has anti-tumor properties while others have found it to be pro-tumorigenic. To unveil the truth, we have analyzed the expression of ß-hCG in breast cancer. We identified for the first time that ß-hCG expression is linked to BRCA1 status and its overexpression is seen in BRCA1 mutated breast cancer cells, BRCA1 conditional knockout mouse breast cancer tissues and BRCA1 floxed basal cell carcinoma (BCC) tissues. An analysis of three large, transcriptomic data sets from TCGA (The Cancer Genome Atlas) expression profile confirmed the inverse correlation between BRCA1 and ß-hCG in human breast cancer. Using ChIP and luciferase assays, we also demonstrated that the cancer cells with wild-type but not mutant BRCA1 directly repress the expression of ß-hCG by binding to its promoter. Further, ß-hCG promotes migration and invasion predominantly in BRCA1 mutant breast cancer cells. Interestingly, stable overexpression of ß-hCG in BRCA1 mutant but not wild-type breast cancer cells results in the formation of spheres even on monolayer cultures. The cells of these spheres show high expression of both EMT and stem cell markers. Since ß-hCG belongs to a cysteine knot family of proteins like TGFß and TGFß signaling is deregulated in BRCA1 defective tumors, we checked whether ß-hCG can mediate signaling through TGFßRII in BRCA1 mutated cells. We found for the first time that ß-hCG can bind and phosphorylate TGFßRII, irrespective of LHCGR status and induce proliferation in BRCA1 defective cells. Our results confirmed that there exists a transcriptional regulation of BRCA1 on ß-hCG and BRCA1 mutation promotes ß-hCG mediated tumorigenesis through TGFßRII signaling. Thus inhibiting ß-hCG-TGFßRII could prove an effective treatment strategy for BRCA1 mutated tumors.

Developmental expression of meprin metalloprotease subunits in ICR and C3H/He mouse kidney and intestine in the embryo, postnatally and after weaning.

Meprins are secreted and membrane-bound metalloendopeptidases highly expressed in kidney and intestinal epithelial cells. They are oligomeric glycoproteins composed of evolutionarily related alpha and/or beta subunits. The present work revealed that the messages for both meprin subunits were expressed in intestine and kidney in ICR and C3H/He mouse embryos (as early as day 11), indicating developmental functions for both subunits. During the first 2 weeks after birth, the mRNA levels for both subunits increased in ICR mice, but between 10 days and 3 weeks (time of weaning) the alpha subunit level in the intestine fell markedly. In adult ICR mice, meprin beta mRNA was consistently expressed in both kidney and intestine, whereas meprin alpha mRNA was highly expressed in kidney but only present at low levels in intestine. In C3H/He mice, the pattern of meprin alpha and beta subunit mRNA expression was similar to that of ICR mice, except that meprin alpha was barely detectable in kidney after birth. The results of postnatal studies indicate that the meprin alpha subunit has a role in the intestine during suckling but is not essential after weaning, and that the beta homooligomer is the major meprin form after weaning in both kidney and intestine.

Structure of the mouse metalloprotease meprin beta gene (Mep1b): alternative splicing in cancer cells.

The mouse meprin beta gene encodes an integral membrane protease that is expressed in a tissue-specific manner in embryonic and adult epithelial cells, and in carcinoma cells. The meprin beta mRNA in the embryo, kidney and intestinal cells is 2.5kb, whereas the isoform in carcinoma cells (beta' mRNA) is 2.7kb. The work herein was initiated to explore the molecular mechanism responsible for the different isoforms. Overlapping fragments containing the Mep1b gene were obtained from a yeast artificial chromosome clone using polymerase chain reactions. The gene spans approximately 40kb and consists of 18 exons and 17 introns. The first three exons are unique to the 5' end of beta' mRNA; the next two exons correspond to the 5' end of beta mRNA. The rest of the exons (13 total) encode the regions common to both beta and beta' messages. In conjunction with the cDNA sequences, the gene structure establishes that alternative splicing of 5' exons is responsible for the generation of the mRNA isoforms. The DNA regions between beta'- and beta-specific exons and upstream of the first beta' exon have been completely sequenced to identify potential regulatory elements for beta and beta' transcription. There is significant homology between the two regions, indicating that a duplication event occurred during evolution of the Mep1b gene. Potential promoter elements and transcription factor-binding sites were identified from comparisons to sequences in the databanks. This is the first gene structure that has been completed for meprin subunits from all species. The work elucidates molecular mechanisms that regulate differential expression of the Mep1b gene.

Sgk, a putative serine/threonine kinase, is differentially expressed in the kidney of diabetic mice and humans.

Differential display PCR was used to identify alternate expression of serum glucocorticoid-regulated kinase (Sgk) mRNA in diabetes-induced renal disease. Differential expression of Sgk mRNA was identified in the kidneys of normal and obese db/db mice, a model of select aspects of human diabetic nephropathy. Sgk mRNA was selectively increased in diabetic mouse kidneys. The Sgk mRNA levels remained constant in other tissues from obese db/db mice. An increase in Sgk mRNA was also observed in the human diabetic kidney. In addition, thrombin, which may play a role in the progression of renal disease, increased Sgk message in cell culture. Because the diabetes-induced increase in Sgk was only observed in the kidney, which is particularly susceptible to diabetes-induced damage, Sgk may play a role in diabetic nephropathy.

Minneapolis hip prosthesis in severe destructive lesions of the femur.

The use of the Minneapolis prosthesis was abandoned about 1955 by its originators, who had used it without acrylic for uncomplicated fractures of the femoral neck. This is the first report of its use with 'cement' fixation. It has been found to be very useful and reliable for arthroplasty of the hip in 57 patients with carcinomatous or other severe destructive lesions in the trochanteric region of the femur, being more convenient and easier to use than alternative prostheses and especially valuable in metastatic disease. Technical points relating to operative techniques are described, and postoperative Hamilton-Russell traction is recommended.

Fistula between the hip and the caecum.

A patient is reported who developed a fistula between the hip and the caecum 39 years after arthrodesis of her hip. She presented with a painful right hip and radiographs showed that the Smith-Petersen nail used for arthrodesis had moved up through the acetabulum and into the pelvic cavity. The nail was removed but within a week a fistula which discharged alimentary contents had developed between the hip and the caecum. The patient was treated conservatively, and three weeks later the fistula had closed.