Biomedical subjects

Jinsong Liu

Publications and source records attributed to Jinsong Liu.

At least 37 records · Page 2Linked to original sources

PubMed2006

Use of Ras-transformed human ovarian surface epithelial cells as a model for studying ovarian cancer.

The Ras gene family has been implicated in the development of many human epithelial cancers. Mutations in K-ras or its downstream mediator BRAF have been detected in about two thirds of low-grade serous carcinomas and borderline serous tumors; mutations in K-ras are also often present in benign and invasive mucinous ovarian cancers. Although the oncogenic allele H-ras(V12) is present in only approximately 6% of ovarian cancers, physiologically activated H-ras protein is commonly detected in human ovarian cancer, presumably because of an increase in upstream signals from tyrosine kinase growth factor receptors such as Her-2/neu, despite the lack of a Ras mutation. The mechanisms by which ras oncogenes transform human epithelial cells are not clear. The methods described here are what we use to culture human ovarian surface epithelial cells, to immortalize those cells, and to transform the immortalized cells with oncogenic H-ras or K-ras. These Ras-transformed human ovarian surface epithelial cells form tumors in nude mice and recapitulate many features of human ovarian cancer, thus providing an excellent model system for studying the initiation and progression of human ovarian cancer.

Animals↗

PubMed2006

Physical characterization of pharmaceutical formulations in frozen and freeze-dried solid states: techniques and applications in freeze-drying development.

Physical characterization of formulations in frozen and freeze-dried solid states provides indispensable information for rational development of freeze-dried pharmaceutical products. This article provides an overview of the physical characteristics of formulations in frozen and freeze-dried solid states, which are essential to both formulation and process development. Along with a brief description of techniques often used in physical characterization for freeze-drying development, applications of and recent improvements to these techniques are discussed. While most of these techniques are used conventionally in physical characterization of pharmaceuticals, some techniques were designed or modified specifically for studies in freeze-drying. These include freeze-drying microscopy, freeze-drying X-ray powder diffractometry and cryoenvironmental scanning microscopy, which can be used to characterize the physical properties of the formulation under conditions similar to the real vial lyophilization process. Novel applications of some conventional techniques, such as microcalorimetry and near infrared (NIR) spectroscopy, which facilitated freeze-drying development, receive special attention. Research and developmental needs in the area of physical characterization for freeze-drying are also addressed, particularly the need for a better understanding of the quantitative correlation between the molecular mobility and the storage stability (shelf life).

Animals↗

PubMed2006

Endometrioid carcinoma simultaneously involving the uterus and the fallopian tube: a clinicopathologic study of 13 cases.

Although the simultaneous presentation of endometrial and ovarian carcinomas of the endometrioid type is well described, little is known about a similar phenomenon involving the endometrium and fallopian tube (FT). We present the clinicopathologic features of 13 such cases seen in the Department of Pathology at The University of Texas M.D. Anderson Cancer Center over an 8 year period (1995 to 2002). FT tumors that could have represented luminal extension of the endometrial carcinoma or that represented an unequivocal metastasis to the FT were excluded. The patients' ages ranged from 34 to 77 years (median 54). The most common symptom was abnormal uterine/vaginal bleeding (11) and all of the patients were considered overweight or obese (mean body mass index was 41). The size of the endometrial carcinomas ranged from 0.3 to 8 cm. According to the FIGO grading of the endometrial endometrioid carcinomas, the cases were distributed as follows: Grade 1 (3) and Grade 2 (10). In 2 cases, there were also small areas of other histologic types, papillary serous carcinoma (1 case), and papillary endometrial carcinoma of intermediate grade (another case). The size of the fallopian tube carcinomas ranged from 0.2 to 17.5 cm. Seven of these tumors were located in the distal/fimbriated end of the FT. There was bilateral involvement in 2 cases. Three of the FT tumors were in situ. The grades of the fallopian tube carcinomas were as follows: Grade 1 (2), Grade 2 (6), and Grade 3 (2). In situ components were seen in all cases. One fallopian tube carcinoma was mixed with serous carcinoma. In 4 cases, there was also an endometrioid carcinoma involving the ovary, all of them with an intact ovarian capsule. Patients were treated as follows: total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH/BSO) (4), TAH/BSO/chemotherapy (chemo) (4), TAH/BSO/radiation (3), and TAH/BSO/chemo/radiation (2). Follow-up ranging from 6 to 54 months was available in 10 patients: 1 patient died of disease (at 38 mo), 1 patient is alive with disease (at 9 mo), 7 patients have no evidence of disease (6 to 54 mo), and 1 patient died of metastatic endometrial carcinoma (at 9 mo). Simultaneous endometrioid carcinomas of the uterus and FT are unusual and occur primarily in obese perimenopausal women. The tumors are predominantly well or moderately differentiated with dissimilar endometrial and FT grades. The FT carcinoma is usually unilateral and located at the distal end of the tube.

Adult↗

PubMed2005

RAS-mediated epigenetic inactivation of OPCML in oncogenic transformation of human ovarian surface epithelial cells.

Opioid binding protein/cell adhesion molecule-like gene (OPCML), a recently identified tumor-suppressor, is frequently inactivated by allele loss and CpG island promoter methylation in epithelial ovarian cancer. Since elevated activation of the RAS signaling pathway, including overexpression of HER-2/neu and mutations of RAS and BRAF, is common in human ovarian carcinoma, we examined the cellular effect of oncogenic RAS on the expression status of OPCML in a genetically defined human ovarian cancer model. Our study revealed that RAS(V12)-mediated oncogenic transformation was accompanied by a concomitant loss of OPCML expression. Methylation-sensitive PCR analysis showed that the OPCML promoter was hypermethylated in RAS-transformed human ovarian epithelial cells (T29H) and that treatment with the DNA methyltransferase inhibitor 5'-aza-2'-deoxycytidine promoted demethylation of the OPCML promoter and restored OPCML expression in T29H cells. Furthermore, suppression of oncogenic RAS activity by stable siRNA specific for HRAS(V12) led to the demethylation and re-expression of OPCML in T29H cells, demonstrating that oncogenic RAS activity is directly responsible for the observed OPCML promoter hypermethylation and epigenetic gene silencing of OPCML. Taken together, our study suggests that elevation of the RAS signaling pathway may play an important role in epigenetic inactivation of OPCML in human epithelial ovarian cancer.

Azacitidine↗

PubMed2005

Association of fragile site-associated (FSA) gene expression with epithelial differentiation and tumor development.

A novel gene designated as fragile site-associated (FSA) gene was recently identified by positional cloning from the CHO 1q31 fragile site which plays an important role in regulating amplification of multidrug resistance (mdr1) gene in multidrug-resistant cells. FSA produces a message of approximately 16 kb which encodes an open-reading frame of 5005 amino acids. FSA shares sequence similarity with that in Caenorhabditis elegans lpd-3, a lipid storage gene. Using immunohistochemical staining and RNA in situ hybridization we report here that expression of FSA is associated with developmental programs of spermatogenesis and mammary gland in mice. Real-time RT-PCR results also support the upregulation of FSA expression in mammary gland development. Expression of FSA in many tissues including colon, skin, ovary, prostate, and bladder is mainly in the postmitotic, well-differentiated compartments. Moreover, levels of FSA expression are downregulated in tumors of these tissue origins. These results suggest that FSA also plays important roles in regulating mammalian epithelial growth and differentiation and tumor development.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

OSW-1: a natural compound with potent anticancer activity and a novel mechanism of action.

The naturally occurring compound 3beta,16beta,17alpha-trihydroxycholest-5-en-22-one 16-O-(2-O-4-methoxybenzoyl-beta-D-xylopyranosyl)-(1-->3)-(2-O-acetyl-alpha-L-arabinopyranoside) (OSW-1) is found in the bulbs of Ornithogalum saudersiae and is highly cytotoxic against tumor cell lines. Using various human cancer and nonmalignant cell lines, we investigated the anticancer activity and selectivity of OSW-1 and its underlying mechanisms of action. OSW-1 exhibited extremely potent cytotoxic activity against cancer cells in vitro. Nonmalignant cells were statistically significantly less sensitive to OSW-1 than cancer cells, with concentrations that cause a 50% loss of cell viability 40-150-fold greater than those observed in malignant cells. Electron microscopy and biochemical analyses revealed that OSW-1 damaged the mitochondrial membrane and cristae in both human leukemia and pancreatic cancer cells, leading to the loss of transmembrane potential, increase of cytosolic calcium, and activation of calcium-dependent apoptosis. Clones of leukemia cells with mitochondrial DNA defects and respiration deficiency that had adapted the ability to survive in culture without mitochondrial respiration also were resistant to OSW-1. In vitro analysis revealed that OSW-1 effectively killed primary leukemia cells from chronic lymphocytic leukemia patients with disease refractory to fludarabine. The promising anticancer activity of OSW-1 and its unique mechanism of action make this compound worthy of further investigation for its potential to overcome drug resistance.

Antineoplastic Agents↗

PubMed2005

Steroid receptor coactivator-3, a homolog of Taiman that controls cell migration in the Drosophila ovary, regulates migration of human ovarian cancer cells.

Border cell migration is a process that occurs during Drosophila ovarian development in which cells derived from a simple epithelium migrate and invade neighboring tissue. This process resembles the behavior of cancerous cells that derive from the simple epithelium of the human ovary. One important regulator of border cell migration is Taiman, a homolog of steroid receptor coactivator-3 (SRC-3). Because increasing evidence indicates that similarities exist between the molecular control of migration of border cells and of cancer cells, we investigated whether SRC-3 controls ovarian cancer cell migration. Little or no SRC-3 expression was detected in normal ovarian surface epithelium, ovarian cysts and borderline ovarian tumors that lack stromal invasion. In contrast, SRC-3 was abundantly expressed in high-grade ovarian carcinomas. Inhibiting SRC-3 expression in ovarian cancer cells markedly reduced cell spreading and migration, and altered intracellular localization of focal adhesion kinase. This inhibitory effect on cell migration was independent of the estrogen receptor (ER) status of the cells. These studies reveal a novel role for SRC-3 in ovarian cancer progression by promoting cell migration, independently of its role in estrogen receptor signaling.

Acetyltransferases↗

PubMed2005

The carboxyl-terminal of BRCA1 is required for subnuclear assembly of RAD51 after treatment with cisplatin but not ionizing radiation in human breast and ovarian cancer cells.

BRCA1 plays an important role in maintaining genomic stability through its involvement in DNA repair. Although it is known that BRCA1 and RAD51 form distinct DNA repair subnuclear complexes, or foci, following environmental insults to the DNA, the role of BRCA1 in this process remains to be characterized. The purpose of the study was therefore to determine the role of BRCA1 in the formation of RAD51 foci following treatment with cisplatin and ionizing radiation. We found that although a functional BRCA1 is required for the subnuclear assembly of BRCA1 foci following treatment with either ionizing radiation or cisplatin, a functional BRCA1 is required for RAD51 foci to form following treatment with cisplatin but not with ionizing radiation. Similar results were obtained in SKOV-3 cells when the level of BRCA1 expression was knocked down by stable expression of a retrovirus-mediated small-interfering RNA against BRCA1. We also found that the carboxyl-terminal of BRCA1 contains uncharacterized phosphorylation sites that are responsive to cisplatin. The functional BRCA1 is also required for breast and ovarian cancer cells to mount resistance to cisplatin. These results suggest that the carboxyl-terminal of BRCA1 is required for the cisplatin-induced recruitment of RAD51 to the DNA-damage site, which may contribute to cisplatin resistance.

Antineoplastic Agents↗

PubMed2005

Misregulated Wnt/beta-catenin signaling leads to ovarian granulosa cell tumor development.

Misregulation of the Wnt/beta-catenin signaling pathway is a hallmark of several forms of cancer. Components of the Wnt/beta-catenin pathway are expressed in ovarian granulosa cells; nevertheless, its potential involvement in granulosa cell tumorigenesis has not been examined. To this end, human (n = 6) and equine (n = 18) granulosa cell tumors (GCT) were analyzed for beta-catenin expression by immunohistochemistry. Unlike granulosa cells of normal ovaries, most (15 of 24) GCT samples showed nuclear localization of beta-catenin, suggesting that activation of the Wnt/beta-catenin pathway plays a role in the etiology of GCT. To confirm this hypothesis, Catnb(flox(ex3)/+); Amhr2(cre/+) mice that express a dominant stable beta-catenin mutant in their granulosa cells were generated. These mice developed follicle-like structures containing disorganized, pleiomorphic granulosa by 6 weeks of age. Even in older mice, these follicle-like lesions grew no larger than the size of antral follicles and contained very few proliferating cells. Similar to corpora lutea, the lesions were highly vascularized, although they did not express the luteinization marker Cyp11a1. Catnb(flox(ex3)/+); Amhr2(cre/+) females were also found to be severely subfertile, and fewer corpora lutea were found to form in response to exogenous gonadotropin compared with control mice. In older mice, the ovarian lesions often evolved into GCT, indicating that they represent a pretumoral intermediate stage. The GCT in Catnb(flox(ex3)/+); Amhr2(cre/+) mice featured many histopathologic similarities to the human disease, and prevalence of tumor development attained 57% at 7.5 months of age. Together, these studies show a causal link between misregulated Wnt/beta-catenin signaling and GCT development and provide a novel model system for the study of GCT biology.

Animals↗

PubMed2005

Mitochondrial manganese-superoxide dismutase expression in ovarian cancer: role in cell proliferation and response to oxidative stress.

Superoxide dismutases (SODs) are important antioxidant enzymes responsible for the elimination of superoxide radical (O(2)(-)). The manganese-containing SOD (Mn-SOD) has been suggested to have tumor suppressor function and is located in the mitochondria where the majority of O(2)(-) is generated during respiration. Although increased reactive oxygen species (ROS) in cancer cells has long been recognized, the expression of Mn-SOD in cancer and its role in cancer development remain elusive. The present study used a human tissue microarray to analyze Mn-SOD expression in primary ovarian cancer tissues, benign ovarian lesions, and normal ovary epithelium. Significantly higher levels of Mn-SOD protein expression were detected in the malignant tissues compared with normal tissues (p < 0.05). In experimental systems, suppression of Mn-SOD expression by small interfering RNA caused a 70% increase of superoxide in ovarian cancer cells, leading to stimulation of cell proliferation in vitro and more aggressive tumor growth in vivo. Furthermore, stimulation of mitochondrial O(2)(-) production induced an increase of Mn-SOD expression. Our findings suggest that the increase in Mn-SOD expression in ovarian cancer is a cellular response to intrinsic ROS stress and that scavenging of superoxide by SOD may alleviate the ROS stress and thus reduce the simulating effect of ROS on cell growth.

Animals↗

PubMed2005

Proteomics analysis of H-RAS-mediated oncogenic transformation in a genetically defined human ovarian cancer model.

RAS is a small GTP binding protein mutated in approximately 30% human cancer. Despite its important role in the initiation and progression of human cancer, the underlying mechanism of RAS-induced human epithelial transformation remains elusive. In this study, we probe the cellular and molecular mechanisms of RAS-mediated transformation, by profiling two human ovarian epithelial cell lines. One cell line was immortalized with SV40 T/t antigens and the human catalytic subunit of telomerase (T29), while the second cell line was transformed with an additional oncogenic ras(V12) allele (T29H). In total, 32 proteins associated with RAS-mediated transformation have been identified using peptide mass fingerprinting. These protein targets are involved in several cellular pathways, including metabolism, redox balance, calcium signaling, apoptosis, and cellular methylation. One such target, the 40 kDa procaspase 4 is significantly upregulated at the protein level in RAS-transformed T29H cells, related directly to signaling through MEK, but not PI3 kinase. Cellular caspase 4 activity is, however, suppressed in the T29H cells, suggesting that the maturation process of caspase 4 is abrogated in RAS-transformed T29H cells. Consistent with this notion, transformed T29H cells were less susceptible to the toxic effects of anti-Fas antibody than were immortalized, nontransformed T29 cells, associated with less activation of caspase 4. This study demonstrates that functional proteomic analysis of a genetically defined cancer model provides a powerful approach toward systematically identifying cellular targets associated with oncogenic transformation.

Apoptosis↗

PubMed2005

Patterns of gene expression in different histotypes of epithelial ovarian cancer correlate with those in normal fallopian tube, endometrium, and colon.

PURPOSE: Epithelial ovarian cancers are thought to arise from flattened epithelial cells that cover the ovarian surface or that line inclusion cysts. During malignant transformation, different histotypes arise that resemble epithelial cells from normal fallopian tube, endometrium, and intestine. This study compares gene expression in serous, endometrioid, clear cell, and mucinous ovarian cancers with that in the normal tissues that they resemble. EXPERIMENTAL DESIGN: Expression of 63,000 probe sets was measured in 50 ovarian cancers, in 5 pools of normal ovarian epithelial brushings, and in mucosal scrapings from 4 normal fallopian tube, 5 endometrium, and 4 colon specimens. Using rank-sum analysis, genes whose expressions best differentiated the ovarian cancer histotypes and normal ovarian epithelium were used to determine whether a correlation based on gene expression existed between ovarian cancer histotypes and the normal tissues they resemble. RESULTS: When compared with normal ovarian epithelial brushings, alterations in serous tumors correlated with those in normal fallopian tube (P = 0.0042) but not in other normal tissues. Similarly, mucinous cancers correlated with those in normal colonic mucosa (P = 0.0003), and both endometrioid and clear cell histotypes correlated with changes in normal endometrium (P = 0.0172 and 0.0002, respectively). Mucinous cancers displayed the greatest number of alterations in gene expression when compared with normal ovarian epithelial cells. CONCLUSION: Studies at a molecular level show distinct expression profiles of different histologies of ovarian cancer and support the long-held belief that histotypes of ovarian cancers come to resemble normal fallopian tube, endometrial, and colonic epithelium. Several potential molecular markers for mucinous ovarian cancers have been identified.

Adenocarcinoma, Clear Cell↗

PubMed2005

Atypical PKCiota contributes to poor prognosis through loss of apical-basal polarity and cyclin E overexpression in ovarian cancer.

We show that atypical PKCiota, which plays a critical role in the establishment and maintenance of epithelial cell polarity, is genomically amplified and overexpressed in serous epithelial ovarian cancers. Furthermore, PKCiota protein is markedly increased or mislocalized in all serous ovarian cancers. An increased PKCiota DNA copy number is associated with decreased progression-free survival in serous epithelial ovarian cancers. In a Drosophila in vivo epithelial tissue model, overexpression of persistently active atypical PKC results in defects in apical-basal polarity, increased Cyclin E protein expression, and increased proliferation. Similar to the Drosophila model, increased PKCiota proteins levels are associated with increased Cyclin E protein expression and proliferation in ovarian cancers. In nonserous ovarian cancers, increased PKCiota protein levels, particularly in the presence of Cyclin E, are associated with markedly decreased overall survival. These results implicate PKCiota as a potential oncogene in ovarian cancer regulating epithelial cell polarity and proliferation and suggest that PKCiota is a novel target for therapy.

Animals↗

PubMed2005

Potential markers that complement expression of CA125 in epithelial ovarian cancer.

BACKGROUND: When ovarian carcinoma is diagnosed in stage I, up to 90% of patients can be cured with surgery and currently available chemotherapy. At present, less than 25% of cases are diagnosed at this stage. To increase the fraction of ovarian cancers detected at an early stage, screening strategies have been devised that utilize a rising serum CA125 level to trigger the performance of transvaginal sonography. One limitation of CA125 as an initial step in such a screening strategy is that up to 20% of ovarian cancers lack expression of the antigen. Serum tumor markers that can be detected in ovarian cancers that lack CA125 expression might improve the sensitivity for early detection. METHODS: From 296 ovarian cancers, 65 (22%) were found to have weak or absent CA125 expression on immunoperoxidase staining. Tissue expression of CA125 was compared to serum CA125 levels. Using immunoperoxidase staining of tissue arrays, we have assessed expression of 10 potential serum tumor markers in the 65 epithelial ovarian cancers with little or no CA125 expression and in ovarian cystadenomas, tumors of low malignant potential, normal ovaries, and 16 other normal tissues. RESULTS: Low or absent expression of CA125 in surgical specimens of epithelial ovarian cancer was associated with low levels of serum CA125 in pre-operative serum specimens. In ovarian cancers that lacked CA125, all specimens (100%) expressed human kallikrein 10 (HK10), human kallikrein 6 (HK6), osteopontin (OPN), and claudin 3. A smaller fraction of CA125-deficient ovarian cancers expressed DF3 (95%), vascular endothelial growth factor (VEGF) (81%), MUC1 (62%), mesothelin (MES) (34%), HE4 (32%), and CA19-9 (29%). When reactivity with normal tissues was considered, however, MES and HE4 showed the greatest specificity. Differential expression was also found for HK10, OPN, DF3, and MUC1. CONCLUSIONS: At the level of tissue expression, each of 10 potential serum markers could be detected in 29-100% of ovarian cancers that had low or absent expression of CA125. Several markers exhibited more intense expression in cancers than in normal organs. Further investigation is needed to demonstrate complementary expression of markers in serum.

Antigens↗

PubMed2005

WWOX protein expression varies among ovarian carcinoma histotypes and correlates with less favorable outcome.

BACKGROUND: The putative tumor suppressor WWOX gene spans the common chromosomal fragile site 16D (FRA16D) at chromosome area 16q23.3-24.1. This region is a frequent target for loss of heterozygosity and chromosomal rearrangement in ovarian, breast, hepatocellular, prostate carcinomas and other neoplasias. The goal of these studies was to evaluate WWOX protein expression levels in ovarian carcinomas to determine if they correlated with clinico-pathological parameters, thus providing additional support for WWOX functioning as a tumor suppressor. METHODS: We performed WWOX protein expression analyses by means of immunobloting and immunohistochemistry on normal ovaries and specific human ovarian carcinoma Tissue Microarrays (n = 444). Univariate analysis of clinical-pathological parameters based on WWOX staining was determined by chi2 test with Yates' correction. The basic significance level was fixed at p < 0.05. RESULTS: Immunoblotting analysis from normal ovarian samples demonstrated consistently strong WWOX expression while 37% ovarian carcinomas showed reduced or undetectable WWOX protein expression levels. The immunohistochemistry of normal human ovarian tissue sections confirmed strong WWOX expression in ovarian surface epithelial cells and in epithelial inclusion cysts within the cortex. Out of 444 ovarian carcinoma samples analyzed 30% of tumors showed lack of or barely detectable WWOX expression. The remaining ovarian carcinomas (70%) stained moderately to strongly positive for this protein. The two histotypes showing significant loss of WWOX expression were of the Mucinous (70%) and Clear Cell (42%) types. Reduced WWOX expression demonstrated a significant association with clinical Stage IV (FIGO) (p = 0.007), negative Progesterone Receptor (PR) status (p = 0.008) and shorter overall survival (p = 0.03). CONCLUSION: These data indicate that WWOX protein expression is highly variable among ovarian carcinoma histotypes. It was also observed that subsets of ovarian tumors demonstrated loss of WWOX expression and is potentially associated with patient outcome.

Blotting, Western↗

PubMed2005

Lineage infidelity of epithelial ovarian cancers is controlled by HOX genes that specify regional identity in the reproductive tract.

Although epithelial ovarian cancers (EOCs) have been thought to arise from the simple epithelium lining the ovarian surface or inclusion cysts, the major subtypes of EOCs show morphologic features that resemble those of the müllerian duct-derived epithelia of the reproductive tract. We found that HOX genes, which normally regulate mullerian duct differentiation, are not expressed in normal ovarian surface epithelium (OSE), but are expressed in different EOC subtypes according to the pattern of mullerian-like differentiation of these cancers. Ectopic expression of Hoxa9 in tumorigenic mouse OSE cells gave rise to papillary tumors resembling serous EOCs. In contrast, Hoxa10 and Hoxa11 induced morphogenesis of endometrioid-like and mucinous-like EOCs, respectively. Hoxa7 showed no lineage specificity, but promoted the abilities of Hoxa9, Hoxa10 and Hoxa11 to induce differentiation along their respective pathways. Therefore, inappropriate activation of a molecular program that controls patterning of the reproductive tract could explain the morphologic heterogeneity of EOCs and their assumption of müllerian-like features.

Animals↗

PubMed2005

Insulin-like growth factor binding protein 2 promotes ovarian cancer cell invasion.

BACKGROUND: Insulin-like growth factor binding protein 2 (IGFBP2) is overexpressed in ovarian malignant tissues and in the serum and cystic fluid of ovarian cancer patients, suggesting an important role of IGFBP2 in the biology of ovarian cancer. The purpose of this study was to assess the role of increased IGFBP2 in ovarian cancer cells. RESULTS: Using western blotting and tissue microarray analyses, we showed that IGFBP2 was frequently overexpressed in ovarian carcinomas compared with normal ovarian tissues. Furthermore, IGFBP2 was significantly overexpressed in invasive serous ovarian carcinomas compared with borderline serous ovarian tumors. To test whether increased IGFBP2 contributes to the highly invasive nature of ovarian cancer cells, we generated IGFBP2-overexpressing cells from an SKOV3 ovarian cancer cell line, which has a very low level of endogenous IGFBP2. A Matrigel invasion assay showed that these IGFBP2-overexpressing cells were more invasive than the control cells. We then designed small interference RNA (siRNA) molecules that attenuated IGFBP2 expression in PA-1 ovarian cancer cells, which have a high level of endogenous IGFBP2. The Matrigel invasion assay showed that the attenuation of IGFBP2 expression indeed decreased the invasiveness of PA-1 cells. CONCLUSIONS: We therefore showed that IGFBP2 enhances the invasion capacity of ovarian cancer cells. Blockage of IGFBP2 may thus constitute a viable strategy for targeted cancer therapy.

Cell Line, Tumor↗

PubMed2005

The Genomes of Oryza sativa: a history of duplications.

We report improved whole-genome shotgun sequences for the genomes of indica and japonica rice, both with multimegabase contiguity, or almost 1,000-fold improvement over the drafts of 2002. Tested against a nonredundant collection of 19,079 full-length cDNAs, 97.7% of the genes are aligned, without fragmentation, to the mapped super-scaffolds of one or the other genome. We introduce a gene identification procedure for plants that does not rely on similarity to known genes to remove erroneous predictions resulting from transposable elements. Using the available EST data to adjust for residual errors in the predictions, the estimated gene count is at least 38,000-40,000. Only 2%-3% of the genes are unique to any one subspecies, comparable to the amount of sequence that might still be missing. Despite this lack of variation in gene content, there is enormous variation in the intergenic regions. At least a quarter of the two sequences could not be aligned, and where they could be aligned, single nucleotide polymorphism (SNP) rates varied from as little as 3.0 SNP/kb in the coding regions to 27.6 SNP/kb in the transposable elements. A more inclusive new approach for analyzing duplication history is introduced here. It reveals an ancient whole-genome duplication, a recent segmental duplication on Chromosomes 11 and 12, and massive ongoing individual gene duplications. We find 18 distinct pairs of duplicated segments that cover 65.7% of the genome; 17 of these pairs date back to a common time before the divergence of the grasses. More important, ongoing individual gene duplications provide a never-ending source of raw material for gene genesis and are major contributors to the differences between members of the grass family.

Base Sequence↗