Novel insights into the expression of CGB1 & 2 genes by epithelial cancer cell lines secreting ectopic free hCGß.

BACKGROUND: Ectopic secretion of human chorionic gonadotrophin free beta (hCGß) by epithelial cancer is associated with aggressive tumors which more readily metastasize, possibly by acting as an autocrine anti-apoptotic agent. hCGß is encoded by six homologous CGB genes, with poorly-understood variable transcriptionally active expression profiles; CGB1 and CGB2 have always been considered pseudogenes. However, transcripts from CGB1 and -2 can be detected in placental, testicular and pituitary tissues. The expression and function of these genes in cancer is less well-known. MATERIALS AND METHODS: Expression profiles of CGB genes in epithelial cancer cells by quantitative polymerase chain reaction (qPCR) were explored, along with the consequence of specific siRNA silencing of CGB1 and 2. Immunohistochemical and immunoassay techniques were used to detect the translation and secretion of hCGß in these cells. RESULTS: CGB1 and -2 gene transcripts were only detected in cells which secreted hCGß. siRNA-mediated silencing of CGB1 and -2 transcripts significantly reduced secreted protein in concordance with a reduction in cell survival to a greater degree than that of other CGB genes. CONCLUSION: CGB genes 1 and 2, previously considered as pseudogenes, are notably expressed by epithelial cancer cell lines. The transcription of these genes, but not other CGB genes, correlates with a functionally expressed protein and propensity for cancer growth.

GLI1 confers profound phenotypic changes upon LNCaP prostate cancer cells that include the acquisition of a hormone independent state.

The GLI (GLI1/GLI2) transcription factors have been implicated in the development and progression of prostate cancer although our understanding of how they actually contribute to the biology of these common tumours is limited. We observed that GLI reporter activity was higher in normal (PNT-2) and tumourigenic (DU145 and PC-3) androgen-independent cells compared to androgen-dependent LNCaP prostate cancer cells and, accordingly, GLI mRNA levels were also elevated. Ectopic expression of GLI1 or the constitutively active ΔNGLI2 mutant induced a distinct cobblestone-like morphology in LNCaP cells that, regarding the former, correlated with increased GLI2 as well as expression of the basal/stem-like markers CD44, ß1-integrin, ΔNp63 and BMI1, and decreased expression of the luminal marker AR (androgen receptor). LNCaP-GLI1 cells were viable in the presence of the AR inhibitor bicalutamide and gene expression profiling revealed that the transcriptome of LNCaP-GLI1 cells was significantly closer to DU145 and PC-3 cells than to control LNCaP-pBP (empty vector) cells, as well as identifying LCN2/NGAL as a highly induced transcript which is associated with hormone independence in breast and prostate cancer. Functionally, LNCaP-GLI1 cells displayed greater clonal growth and were more invasive than control cells but they did not form colonies in soft agar or prostaspheres in suspension suggesting that they do not possess inherent stem cell properties. Moreover, targeted suppression of GLI1 or GLI2 with siRNA did not reverse the transformed phenotype of LNCaP-GLI1 cells nor did double GLI1/GLI2 knockdowns activate AR expression in DU145 or PC-3 cells. As such, early targeting of the GLI oncoproteins may hinder progression to a hormone independent state but a more detailed understanding of the mechanisms that maintain this phenotype is required to determine if their inhibition will enhance the efficacy of anti-hormonal therapy through the induction of a luminal phenotype and increased dependency upon AR function.

Gonadotropins and prostate cancer: revisited.

Luteinizing hormone and follicle-stimulating hormone are called gonadotropins, because they stimulate the gonads - in males the testes and in females the ovaries. They are not necessary for life, but are essential for reproduction. In addition, the association of these hormones with prostate cancer has been the interest of many researchers. Their detection in the human prostate has been investigated using different methods, including immunologic and RT-PCR techniques. In addition, the increasing evidence of paracrine/autocrine functions of the gonadotropic glycoprotein hormones, their allocation to the superfamily of cystine knot growth factors, and luteinizing hormone/chorionic gonadotropin receptor gene expression in non-gonadal tissues led many researchers to investigate intraprostatic glycoprotein hormones and their receptor gene expression. We aim in this review to shed light on the physiology of the gonadotropins and their association with prostate cancer and highlight the future possibilities of their use as targets in treating this disease.

Association between large-scale genomic homozygosity without chromosomal loss and nonseminomatous germ cell tumor development.

The genotype of a tumor determines its biology and clinical behavior. The genetic alterations associated with the unique embryonal morphology of nonseminomatous subtypes of testicular germ cell tumors remain to be established. Using single nucleotide polymorphism microarray analysis, we found in all of the 15 nonseminomas analyzed, large-scale chromosomal homozygosities, most of which were not associated with relative chromosome loss. This unusual genotype, distinguishing nonseminoma from seminomas and other human tumors, may be associated with the special embryonal development morphologic transition of this malignancy. Based on these genetic data, we hypothesized a new potential origin of nonseminomas through sperm fusion. Nonrandom involvement of certain chromosomes also suggests that genes on these chromosome regions may play an important role in nonseminoma development.

A new mouse mutant, skijumper.

Low blood sugar levels are a well-known cause of severe illness and often death in newborn humans, especially those that are small for age. Few of the causes of neonatal hypoglycemia are known, and many remain to be found. We describe a novel mouse mutant, skijumper (skimp), in which pups, despite feeding well, have low levels of glucose and develop opisthotonos, followed by death typically within a few days after birth. Genetic mapping studies have localized the lesion to a approximately 1 cM interval on mouse Chromosome (Chr) 7 between D7Mit318 and D7Mit93. We have carried out extensive analysis to define the phenotype and its likely cause. In addition to low blood glucose, affected skijumper mice have lowglycogen and ketone levels. Mass spectrometric analysis of blood samples has excluded major defects in amino acid metabolism. Initial biochemical analyses suggested a defect in ketogenesis as one possible cause of this phenotype. However, measurements of levels and activities of carnitine, carnitine palmitoyl transferases, and other enzymes involved in ketogenesis, along with studies of mitochondrial structure and function, did not demonstrate significant differences between skijumper, unaffected littermates, and control wild-type mice. These results indicate that abnormal enzyme activity in known pathways does not appear to be the primary biochemical lesion in skijumper. The skijumper may be a new valuable model for studying and understanding one type of neonatal morbidity and death.

C-myc oncoprotein expression and gene amplification in apocrine metaplasia and apocrine change within sclerosing adenosis of the breast.

Overexpression and/or amplification of c-myc oncogene are known to occur in human breast carcinomas, particularly those of high grade. Apocrine metaplasia (APM) is a common finding within fibrocystic change, and in some cases appears to be associated with an elevated risk of subsequent breast cancer. It has been suggested that apocrine metaplasia within sclerosing adenosis of the breast, also called apocrine adenosis (AA), has a premalignant potential. Little, however, is known about cellular level genetic alterations in either APM or AA of the breast. Because of this, c-myc expression and amplification in APM and AA were studied. Fluorescence in situ hybridisation (FISH) is a methodological approach to detecting these genetic alterations. In this study, APM and AA were studied immunohistochemically to detect c-myc oncoprotein expression, and FISH was employed using a DNA probe for the c-myc gene in archival tissue sections of cases of APM and AA of the breast. Nuclear immunostaining for c-myc was seen in all APM and AA cases studied, but amplification of the c-myc gene was not seen in any cases with APM or AA. The results of this study indicate that c-myc overexpression appears to occur early in breast oncogenesis. Amplification of the c-myc gene does not occur in APM or AA of the breast, however, suggesting that this particular genetic alteration constitutes a late event in the pathogenesis of breast carcinomas.