Abstract A27: MicroRNA 21 in adipocyte-derived microvesicles confers taxol-resistance of ovarian cancer cells through down-regulation of Apoptotic Protease Activating Factor 1

Over the past 30 years, there has been a dramatic increase in the incidence of obesity worldwide. As of 2010, approximately one-third of U.S. adults are obese, while another one-third of adults are overweight. Obesity is one of the risk factors for ovarian cancer. Greater than 75% of ovarian cancer patients present with advanced stage disease. Tumors preferentially spread to the omentum, a major site of abdominal fat, where ovarian cancer cells infiltrate omental adipose tissue. Omental adipocytes may interact directly with cancer cells to create a microenvironment niche that supports cancer growth. Recent studies have shown that cells can communicate through the exchange of bioactive molecules via microvesicles (exosomes and ectosomes). Microvesicles fuse with target cell membranes and transfer proteins, lipids, mRNAs and non-coding RNAs from donor to recipient cells. We hypothesize that adipocytes secrete microvesicles containing tumor-supporting factors that promote ovarian cancer progression.

Ion Torrent RNA sequencing and subsequent qRT-PCR analyses were used to identify non-coding microvesicle RNAs secreted by primary cultures of cancer associated adipocytes (CAA), cancer associated fibroblasts (CAF), normal adipocytes, normal fibroblasts and ovarian cancer cells. Of the non-coding microvesicle RNAs identified, microRNA 21 (miR21) showed significantly higher expression in microvesicles secreted from CAA when compared to those from CAF and normal omental adipocytes, fibroblasts, and ovarian cancer cells. Using qRT-PCR of RNA isolated from microdissected frozen tissue and In-situ hybridization on FFPE tissue sections, CAA demonstrated significant higher miR21 expression levels compared to the adjacent cancer cells and normal adipocytes. MiR21 was up-regulated in metastatic ovarian cancer cells in the omentum as compared to those in the primary tumor site. Moreover, strong miR21 staining was observed in omental cancer cells particularly at the invasion front, suggesting that miR21 may be transferred from CAA to their neighboring ovarian cancer cells.

To test this hypothesis, SKOV3 ovarian cancer cells were co-cultured with adipocytes transfected with miR21-FAM or incubated with fluorescently labeled adipocyte-derived microvesicles. Confocal microscopy confirmed the delivery of miR21 by adipocyte-derived microvesicles to cancer cells. Since miR21 expression in tumor cells has been linked with resistance to a variety of chemotherapeutic agents, we further delineated the direct effect of miR21 on the chemoresistance of ovarian cancer cell. The ovarian cancer cell lines, OVCA432 and SKOV3, transfected with miR21 precursor showed an increase in cell survival and a decrease in apoptosis in the presence of taxol. Furthermore, miR21 was significantly up-regulated in taxol-resistant HeyA8-MDR and SKOV3-TR cells as compared to the parental cell lines, HeyA8 and SKOV3, respectively. These data strongly suggest that miR21 may confer taxol resistance to ovarian cancer cells. Using microarray analysis of RNA isolated from SKOV3 cells transfected with the miR21 precursor, we identified a set of chemoresistance-related genes associated with miR21 expression. One of the most significantly down-regulated genes is Apoptotic Protease Activating Factor 1 (APAF1). By qRT-PCR, we confirmed that miR21 over-expression decreased APAF1 mRNA expression levels in OVCA432 and SKOV3 cells. A strong miR21 binding site is predicted on the 3′-UTR of APAF1, suggesting APAF1 is the direct target of miR21.

In summary, up-regulation of miR21 in omental ovarian cancer cells is mediated through transport of miR21 in adipocyte-derived microvesicles from CAA in the omentum. Further, miR21 confers taxol-resistance in ovarian cancer cells by down-regulating APAF1 expression in ovarian cancer cells to decrease taxol-induced apoptosis.

Citation Format: Ngai Na Co, Rosemarie Schmandt, Karen Lu, Samuel Mok. MicroRNA 21 in adipocyte-derived microvesicles confers taxol-resistance of ovarian cancer cells through down-regulation of Apoptotic Protease Activating Factor 1 [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer; 2012 Jan 8-11; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(2 Suppl):Abstract nr A27.

Large prospective study of ovarian cancer screening in high-risk women: CA125 cut-point defined by menopausal status

Previous screening trials for early detection of ovarian cancer in postmenopausal women have used the standard CA125 cut-point of 35 U/mL, the 98th percentile in this population yielding a 2% false positive rate, whereas the same cut-point in trials of premenopausal women results in substantially higher false positive rates. We investigated demographic and clinical factors predicting CA125 distributions, including 98th percentiles, in a large population of high-risk women participating in two ovarian cancer screening studies with common eligibility criteria and screening protocols. Baseline CA125 values and clinical and demographic data from 3,692 women participating in screening studies conducted by the National Cancer Institute-sponsored Cancer Genetics Network and Gynecologic Oncology Group were combined for this preplanned analysis. Because of the large effect of menopausal status on CA125 levels, statistical analyses were conducted separately in pre- and postmenopausal subjects to determine the impact of other baseline factors on predicted CA125 cut-points on the basis of 98th percentile. The primary clinical factor affecting CA125 cut-points was menopausal status, with premenopausal women having a significantly higher cut-point of 50 U/mL, while in postmenopausal subjects the standard cut-point of 35 U/mL was recapitulated. In premenopausal women, current oral contraceptive (OC) users had a cut-point of 40 U/mL. To achieve a 2% false positive rate in ovarian cancer screening trials and in high-risk women choosing to be screened, the cut-point for initial CA125 testing should be personalized primarily for menopausal status (50 for premenopausal women, 40 for premenopausal on OC, and 35 for postmenopausal women).

Omental adipose tissue-derived stromal cells promote vascularization and growth of endometrial tumors

PURPOSE

Adipose tissue contains a population of tumor-tropic mesenchymal progenitors, termed adipose stromal cells (ASC), which engraft in neighboring tumors to form supportive tumor stroma. We hypothesized that intra-abdominal visceral adipose tissue may contain a uniquely tumor-promoting population of ASC to account for the relationship between excess visceral adipose tissue and mortality of intra-abdominal cancers.

EXPERIMENTAL DESIGN

To investigate this, we isolated and characterized ASC from intra-abdominal omental adipose tissue (O-ASC) and characterized their effects on endometrial cancer progression as compared with subcutaneous adipose-derived mesenchymal stromal cells (SC-ASC), bone marrow-derived mesenchymal stromal cells (BM-MSC), and lung fibroblasts. To model chronic recruitment of ASC by tumors, cells were injected metronomically into mice bearing Hec1a xenografts.

RESULTS

O-ASC expressed cell surface markers characteristic of BM-MSC and differentiated into mesenchymal lineages. Coculture with O-ASC increased endometrial cancer cell proliferation in vitro. Tumor tropism of O-ASC and SC-ASC for human Hec1a endometrial tumor xenografts was comparable, but O-ASC more potently promoted tumor growth. Compared with tumors in SC-ASC-injected mice, tumors in O-ASC-injected mice contained higher numbers of large tortuous desmin-positive blood vessels, which correlated with decreased central tumor necrosis and increased tumor cell proliferation. O-ASC exhibited enhanced motility as compared with SC-ASC in response to Hec1a-secreted factors.

CONCLUSIONS

Visceral adipose tissue contains a population of multipotent MSCs that promote endometrial tumor growth more potently than MSCs from subcutaneous adipose tissue. We propose that O-ASCs recruited to tumors express specific factors that enhance tumor vascularization, promoting survival and proliferation of tumor cells.

Genetic variants in TGF-β pathway are associated with ovarian cancer risk

The transforming growth factor-β (TGF-β) signaling pathway is involved in a diverse array of cellular processes responsible for tumorigenesis. In this case-control study, we applied a pathway-based approach to evaluate single-nucleotide polymorphisms (SNPs) in the TGF-β signaling pathway as predictors of ovarian cancer risk. We systematically genotyped 218 SNPs from 21 genes in the TGF-β signaling pathway in 417 ovarian cancer cases and 417 matched control subjects. We analyzed the associations of these SNPs with ovarian cancer risk, performed haplotype analysis and identified potential cumulative effects of genetic variants. We also performed analysis to identify higher-order gene-gene interactions influencing ovarian cancer risk. Individual SNP analysis showed that the most significant SNP was SMAD6: rs4147407, with an adjusted odds ratio (OR) of 1.60 (95% confidence interval [CI], 1.14–2.24, P = 0.0066). Cumulative genotype analysis of 13 SNPs with significant main effects exhibited a clear dose-response trend of escalating risk with increasing number of unfavorable genotypes. In gene-based analysis, SMAD6 was identified as the most significant gene associated with ovarian cancer risk. Haplotype analysis further revealed that two haplotype blocks within SMAD6 were significantly associated with decreased ovarian cancer risk, as compared to the most common haplotype. Gene-gene interaction analysis further categorized the study population into subgroups with different ovarian cancer risk. Our findings suggest that genetic variants in the TGF-β signaling pathway are associated with ovarian cancer risk and may facilitate the identification of high-risk subgroups in the general population.

Earlier age of onset of BRCA mutation-related cancers in subsequent generations

BACKGROUND

Women who are diagnosed with a deleterious mutation in either breast cancer (BRCA) gene have a high risk of developing breast and ovarian cancers at young ages. In this study, the authors assessed age at diagnosis in 2 generations of families with known mutations to investigate for earlier onset in subsequent generations.

METHODS

Of the 132 BRCA-positive women with breast cancer who participated in a high-risk protocol at The University of Texas MD Anderson Cancer Center (Gen 2), 106 women could be paired with a family member in the previous generation (Gen 1) who was diagnosed with a BRCA-related cancer (either breast cancer or ovarian cancer). Age at diagnosis, location of the mutation, and year of birth were recorded. A previously published parametric anticipation model was applied in these genetically predisposed families.

RESULTS

The median age of cancer diagnosis was 42 years (range, 28-55 years) in Gen 2 and 48 years (range, 30-72 years) in Gen 1 (P < .001). [corrected]. In the parametric model, the estimated change in the expected age at onset for the entire cohort was 7.9 years (P < .0001). Statistically significant earlier ages at diagnosis also were observed within subgroups of BRCA1 and BRCA2 mutations, maternal inheritance, paternal inheritance, breast cancer only, and breast cancer-identified and ovarian cancer-identified families.

CONCLUSIONS

Breast and ovarian cancers in BRCA mutation carriers appeared to be diagnosed at an earlier age in later generations. The authors concluded that patients who are younger at the onset of BRCA-related cancers should continue to be tracked to offer appropriate screening modalities at appropriate ages.

Chronic treatment with a glucagon receptor antagonist lowers glucose and moderately raises circulating glucagon and glucagon-like peptide 1 without severe alpha cell hypertrophy in diet-induced obese mice

AIMS/HYPOTHESIS

Antagonism of the glucagon receptor (GCGR) represents a potential approach for treating diabetes. Cpd-A, a potent and selective GCGR antagonist (GRA) was studied in preclinical models to assess its effects on alpha cells.

METHODS

Studies were conducted with Cpd-A to examine the effects on glucose-lowering efficacy, its effects in combination with a dipeptidyl peptidase-4 (DPP-4) inhibitor, and the extent and reversibility of alpha cell hypertrophy associated with GCGR antagonism in mouse models.

RESULTS

Chronic treatment with Cpd-A resulted in effective and sustained glucose lowering in mouse models in which endogenous murine Gcgr was replaced with human GCGR (hGCGR). Treatment with Cpd-A also led to stable, moderate elevations in both glucagon and glucagon-like peptide 1 (GLP-1) levels, which were completely reversible and not associated with a hyperglycaemic overshoot following termination of treatment. When combined with a DPP-4 inhibitor, Cpd-A led to additional improvement of glycaemic control correlated with elevated active GLP-1 levels after glucose challenge. In contrast to Gcgr-knockout mice in which alpha cell hypertrophy was detected, chronic treatment with Cpd-A in obese hGCGR mice did not result in gross morphological changes in pancreatic tissue.

CONCLUSIONS/INTERPRETATION

A GRA lowered glucose effectively in diabetic models without significant alpha cell hypertrophy during or following chronic treatment. Treatment with a GRA may represent an effective approach for glycaemic control in patients with type 2 diabetes, which could be further enhanced when combined with DPP-4 inhibitors.

Fabrication and Nanostructured Surface Layers of Al Alloy by Surface Vibrational Mechanical Attrition

Nanograins were introduced into the surface layers of an Al-alloy during surface vibrational mechanical attrition. Transmission electron microscopy revealed that microstructures developed with an increase in strain, in the following sequence, i.e., lamellar microbands of elongated subgrains, equiaxed submicro-, and nano-grains respectively. The grain subdivision into the subgrains was found to be the main mechanism responsible for grain refinement. The simultaneous evolution of high boundary misorientations was ascribed to the boundary rotation for accommodating further strains. Results showed that the grains could refine remarkably into the nanometer regime (<100 nm) within the outer surface of the layer. The depth of the nanocrystal layers increased and the grain size decreased with the extension of processing time. The nanocrystal layers evidenced an increase in hardness.

The first vitellogenin receptor from a Lepidopteran insect: molecular characterization, expression patterns and RNA interference analysis

The vitellogenin receptor (VgR) belongs to the low-density lipoprotein receptor (LDLR) superfamily, and is an important carrier for the uptake of vitellogenin (Vg) into developing oocytes of all oviparous species. The first full-length message for a VgR from a Lepidopteran insect was cloned and sequenced from the ovary of Spodoptera litura Fabricius (GenBank accession no. GU983858). The coding region consisted of 5370 bp flanked by a 49 bp 5'-untranslated region (UTR) and a 177 bp 3'-UTR, which encoded a 1798-residue protein with a predicted molecular weight (MW) of 201.69 kDa. S. litura VgR (SlVgR)comprised two ligand binding sites with four LDLR class A repeats in the first domain and seven in the second domain, an epidermal growth factor-like domain containing an LDLR class B repeat and a YWXD motif, a transmembrane domain and a cytoplasmic domain. A phylogenetic relationship placed SlVgR as a separate group from the other insects. SlVgR messenger RNA (mRNA) was specifically expressed in the ovarian tissues. The developmental expression patterns showed that VgR mRNA was first transcribed in 6(th) day female pupae and the maximum level of VgR mRNA appeared in 36-h-old adults. Immunoblot analysis detected an ovary-specific VgR protein with a MW of ∼200 kDa, whose development profiles were consistent with VgR mRNA expression patterns. RNA inteference (RNAi) specifically disrupted the VgR gene by injection of 3 or 5 µg VgR double-stranded RNA per insect in 4(th) or 6(th) day pupae. RNAi of SlVgR led to a phenotype characterized by high Vg accumulation in the haemolymph, low Vg deposition in the ovary and the failure of insect spawning. These results mean that VgR is critical for binding Vg and transporting it into the oocytes of the insect ovary, thus playing an important role in insect reproduction.

A randomized prospective study of rehabilitation therapy in the treatment of radiation-induced dysphagia and trismus

PURPOSE

To evaluate the therapeutic effect of rehabilitation therapy on radiation-induced dysphagia and trismus in nasopharyngeal carcinoma (NPC) patients after radiotherapy.

PATIENTS AND METHODS

43 NPC patients after radiotherapy were included. Patients were randomly assigned to either the rehabilitation group or a control group. Both groups were subjected to routine treatment, while the rehabilitation group also received rehabilitation therapy for 3 months. The severity of dysphagia was assessed using the water swallow test, while trismus was evaluated with the LENT/SOMA score and the interincisor distance (IID). The water swallow test, the LENT/SOMA score, as well as IID for both groups before and after treatment were analyzed and compared.

RESULTS

After treatment, the rehabilitation group displayed a significant improvement in swallowing function, while the control group did not. The efficacy rate (percentage of patients with excellent or effective results) of rehabilitation group was higher than that of control group (77% vs. 43%), and the difference was statistically significant (ϰ(2) = 5.32, p = 0.02). IID pretreatment and posttreatment did not show much difference in the rehabilitation group, while in the control group IID significantly decreased posttreatment (1.1 ± 0.36 cm vs.1.8 ± 0.56 cm, p = 0.001). Although the mean IID in patients of both groups decreased after the 3 month follow-up, the decrease in the rehabilitation group was less than that of the control group (0.19 ± 0.5 cm vs. 0.69 ± 0.56 cm, p = 0.004 ). The efficacy rate of trismus in the rehabilitation group was significantly higher than that of the control group (64% vs. 28%, ϰ(2) = 5.31, p = 0.02).

CONCLUSIONS

Rehabilitation training can improve swallow function and slow down the progress of trismus in NPC patients following radiotherapy.

Genetic variants in MicroRNA biosynthesis pathways and binding sites modify ovarian cancer risk, survival, and treatment response

MicroRNAs (miRNA) play important roles in tumorigenesis. Genetic variations in miRNA processing genes and miRNA binding sites may affect the biogenesis of miRNA and the regulatory effect of miRNAs to their target genes, hence promoting tumorigenesis. This study analyzed 226 single nucleotide polymorphisms (SNP) in miRNA processing genes and miRNA binding sites in 339 ovarian cancer cases and 349 healthy controls to assess association with cancer risk, overall survival, and treatment response. Thirteen polymorphisms were found to have significant association with risk. The most significant were 2 linked SNPs (r(2) = 0.99), rs2740351 and rs7813 in GEMIN4 [odds ratio (OR) = 0.71; 95% confidence interval (CI), 0.57-0.87 and OR = 0.71; 95% CI, 0.57-0.88, respectively]. Unfavorable genotype analysis showed the cumulative effect of these 13 SNPs on risk (P for trend < 0.0001). Potential higher order gene-gene interactions were identified, which categorized patients into different risk groups according to their genotypic signatures. In the clinical outcome study, 24 SNPs exhibited significant association with overall survival and 17 SNPs with treatment response. Notably, patients carrying a rare homozygous genotype of rs1425486 in PDGFC had poorer overall survival [hazard ratio (HR) = 2.69; 95% CI, 1.67-4.33] and worse treatment response (OR = 3.38; 95% CI, 1.39-8.19), compared to carriers of common homozygous and heterozygous genotypes. Unfavorable genotype analyses also showed a strong gene-dosage effect with decreased survival and increased risk of treatment nonresponse in patients with greater number of unfavorable genotypes (P for trend < 0.0001). Taken together, miRNA-related genetic polymorphisms may impact ovarian cancer predisposition and clinical outcome both individually and jointly.

A genome-wide association study identifies susceptibility loci for ovarian cancer at 2q31 and 8q24

Ovarian cancer accounts for more deaths than all other gynecological cancers combined. To identify common low-penetrance ovarian cancer susceptibility genes, we conducted a genome-wide association study of 507,094 SNPs in 1,768 individuals with ovarian cancer (cases) and 2,354 controls, with follow up of 21,955 SNPs in 4,162 cases and 4,810 controls, leading to the identification of a confirmed susceptibility locus at 9p22 (in BNC2). Here, we report on nine additional candidate loci (defined as having P ≤ 10⁻⁴) identified after stratifying cases by histology, which we genotyped in an additional 4,353 cases and 6,021 controls. We confirmed two new susceptibility loci with P ≤ 5 × 10⁻⁸ (8q24, P = 8.0 × 10⁻¹⁵ and 2q31, P = 3.8 × 10⁻¹⁴) and identified two additional loci that approached genome-wide significance (3q25, P = 7.1 × 10⁻⁸ and 17q21, P = 1.4 × 10⁻⁷). The associations of these loci with serous ovarian cancer were generally stronger than with other cancer subtypes. Analysis of HOXD1, MYC, TIPARP and SKAP1 at these loci and of BNC2 at 9p22 supports a functional role for these genes in ovarian cancer development.