Multi-ancestry genome-wide association study of kidney cancer identifies 63 susceptibility regions

Here, in a multi-ancestry genome-wide association study meta-analysis of kidney cancer (29,020 cases and 835,670 controls), we identified 63 susceptibility regions (50 novel) containing 108 independent risk loci. In analyses stratified by subtype, 52 regions (78 loci) were associated with clear cell renal cell carcinoma (RCC) and 6 regions (7 loci) with papillary RCC. Notably, we report a variant common in African ancestry individuals ( rs7629500 ) in the 3' untranslated region of VHL, nearly tripling clear cell RCC risk (odds ratio 2.72, 95% confidence interval 2.23-3.30). In cis-expression quantitative trait locus analyses, 48 variants from 34 regions point toward 83 candidate genes. Enrichment of hypoxia-inducible factor-binding sites underscores the importance of hypoxia-related mechanisms in kidney cancer. Our results advance understanding of the genetic architecture of kidney cancer, provide clues for functional investigation and enable generation of a validated polygenic risk score with an estimated area under the curve of 0.65 (0.74 including risk factors) among European ancestry individuals.

Abstract P2-14-06: Characterization of risk factors in breast cancer young adult patients

Background: Breast cancer diagnosis in the age group of 20-34 years represents 4% of breast cancer cases diagnosed at all ages in São Paulo state, Brazil. Risk factors in this age group of patients are little understood, especially in those not reporting familial history of breast/ovarian cancer syndrome (BOCS). Identification of predisposing factors and BRCA1/2 mutations (mut) in young Brazilian patients may contribute to characterize women with increased risk of breast cancer.

Objective: Characterize familial history and risk factors for breast cancer in young adult Brazilian patients and germline mutations in BRCA1/2 genes.

Methodology: Forty-five patients diagnosed with breast cancer at ages 18-35 years were interviewed using a comprehensive questionnaire. Genomic DNA was extracted from peripheral blood and BRCA1/2 mut were screened by Sanger sequencing of coding sequences, analyzed through Mutation Surveyor v.3.20 and searched in BIC Database, LOVD, LOVD-IARC and UMD.

Results: Mean age of patients at time of diagnosis was 33 y (24-35y); mean age of menarche was 13 y (8-19y); 32 (71.1%) patients had at least one born child, median age of first pregnancy was 22 years; 86.7% never smoked; 71.1% were no regular alcoholic drinkers; mean of body mass index was 27.14 (overweight). Most patients were diagnosed with invasive ductal carcinoma (91.1%); grades II or III (95.5%); ER/PR positive (57.8%); triple-negative (TN: 31.1%) or HER2 positive (17.8%). Among them, 22.2% reported positive familial history (NCCN criteria for BOCS). Deleterious mutation in BRCA1/2 genes was found in 17.8% of the patients (BRCA1, n = 3; BRCA2, n = 5). Among 10 and 35 patients reporting or not BOCS familial history, 3 (30%) and 5 (14.3%) respectively, had BRCA1/2mut. All BRCA1mut patients had TN tumors; BRCA2mut patients had ER/PR positive (60%), HER2 positive (20%) or TN tumors (20%). Most patients reported one or two of the following risk factors: early menarche (<12y); current/previous use of oral contraceptive; no breast feeding and no parities. Among 30 patients reporting no familial history and presenting BRCA1/2 wild type, six (20%) and four (13.3%) reported three or four of these risk factors, respectively. Considering breast cancer protective factors, 17.8% of the patients breast fed >16 months and 24.4% were aged <20y at birth of first child. Diet habits are being analyzed.

Conclusion: In young adults with breast cancer there is a trend towards a higher rate of positive familial history among whom there is a trend towards a higher chance of BRCA1/2 mutation. A better characterization of patients reporting no familial history is urgently needed.

Financial Support: FAPESP.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-14-06.

P2-15-08: New Trends for Surgical Treatment of Large Breast Tumors

Introduction: The locally advanced breast cancer is still common in developing countries. The neoadjuvant chemotherapy (NC) allows converting large tumor into operable one. Oncoplastic surgery (OS) adds new techniques to breast conservative treatment(BCT). The association between NC and OS provides the resection of large amount of breast tissue, including skin, with satisfactory aesthetic results.

Objective: Evaluate the possibilities to indicate oncoplastic techniques to determine BCT after NC for large breast tumors.

Material and Methods: A prospective clinical trial (www.clinicaltrials.gov; NCT00820690) study with women breast cancer patients, clinical stage III, no extense skin involvement, submitted to NC, based on four cycles of doxorubicin 60mg/m2 + cyclophosphamide 600 mg/m2 and 4 cycles of paclitaxel 175mg/m2. Preoperative tattoo was realized for all patients to determine the clinical dimensions of the tumor. Tumor size was controlled by physical and radiological exams. The oncoplastic surgeries were offered in accordance to clinical-imaging previous to NC, final response to chemotherapy, tumor localization, tumor size, breast size, oncologic security, patient comorbidities and experience of the surgeon. The skin-sparing mastectomy with immediate breast reconstruction was also considered an oncoplastic technique. The surgical planning has involved the whole area previously marked by the tattoo regardless of tumor response. A detailed analysis of the pathological specimen was provided to confirm the oncologic safety of the treatment. All patients were followed by radiotherapy after surgery.

Results: 50 patients were enrolled. PE tumor median measurement was 6.5 cm (3.0 to 14.0 cm) and pathologic median tumor was 4.0 cm (0 to 14.5cm). Pathologic response was rated as stable disease, progressive disease, partial response and complete response in 18%, 10%, 68% and 4% of the cases, respectively. Pathologic responses were diverse and included tumor micro-fragmentation and macrofragmentation. PE tumor size before chemotherapy correlated best with MRI (ricc 0.588, p < 0.001), as well as pathologic tumor size measured after chemotherapy correlated best with MRI (ricc 0.738, p <0.001). The surgical approach allowed BCT in 34% (17) of patients. Skin involvement was presented in 38% of pathologic specimen regardless previous clinical exam noticed.

Conclusion: Oncoplastic techniques increase the rates of BCT for selected patients in spite of large locally advanced tumors. The surgical planning is fundamental to this approach. This study recommends the full resection of the tumoral area previous to NC, including marked skin, regardless the response to neoadjuvant treatment. Follow-up of these patients will be important for additional information in the future.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-15-08.

Human breast tumor slices: a model for identification of vitamin D regulated genes in the tumor microenvironment

While many studies have addressed the direct effects of 1alpha,25(OH)2D3 on breast cancer (BC) cells, stromal-epithelial interactions, which are important for the tumor development, have been largely ignored. In addition, high concentrations of the hormone, which cannot be attained in vivo, have been used. Our aim was to establish a more physiological breast cancer model, represented by BC tissue slices, which maintain epithelial-mesenchymal interactions, cultured with a relatively low 1alpha,25(OH)2D3 concentration, in order to evaluate the vitamin D pathway. Freshly excised human BC samples were sliced and cultured in complete culture media containing vehicle, 0.5 nM or 100 nM 1alpha,25(OH)2D3 for 24 h. BC slices remained viable for at least 24 h, as evaluated by preserved tissue morphology in hematoxylin and eosin (HE) stained sections and bromodeoxyuridine (BrdU) incorporation by 10% of tumor cells. VDR mRNA expression was detected in all samples and CYP24A1 mRNA expression was induced by 1alpha,25(OH)2D3 in both concentrations (but mainly with 100 nM). Our results indicate that the vitamin D signaling pathway is functional in BC slices, a model which preserves stromal-epithelial interactions and mimics in vivo conditions.

Expression of E-cadherin, Snail and Hakai in epithelial cells isolated from the primary tumor and from peritumoral tissue of invasive ductal breast carcinomas

Epithelial intercellular cohesion, mainly mediated by E-cadherin (CDH1) expression and function, may be deregulated during cancer cell invasion of adjacent tissues and lymphatic and vascular channels. CDH1 expression is down-modulated in invasive lobular breast carcinomas but its regulation in invasive ductal carcinomas (IDC) is less clear. CDH1 expression is repressed by transcription factors such as Snail (SNAI1) and its product is degraded after Hakai ubiquitination. We compared CDH1, SNAI1 and HAKAI mRNA expression in IDC and paired adjacent normal breast tissue and evaluated its relation with node metastasis and circulating tumor cells. Matched tumor/peritumoral and blood samples were collected from 30 patients with early IDC. Epithelial cells from each compartment (tumor/peritumoral) were recovered by an immunomagnetic method and gene expression was determined by real time RT-PCR. There were no differences in CDH1, SNAI1 and HAKAI mRNA expression between tumor and corresponding peritumoral samples and no differential tumoral gene expression according to nodal involvement. Another 30 patients with a long-term follow-up (at least 5 years) and a differential prognosis (good or poor, as defined by breast cancer death) had E-cadherin and Snail protein detected by immunohistochemistry in tumor samples. In this group, E-cadherin-positive expression, but not Snail, may be associated with a better prognosis. This is the first report simultaneously analyzing CDH1, SNAI1 and HAKAI mRNA expression in matched tumor and peritumoral samples from patients with IDC. However, no clear pattern of their expression could distinguish the invasive tumor compartment from its adjacent normal tissue.

Gene expression profiling of clinical stages II and III breast cancer

Clinical stage (CS) is an established indicator of breast cancer outcome. In the present study, a cDNA microarray platform containing 692 genes was used to identify molecular differences between CSII and CSIII disease. Tumor samples were collected from patients with CSII or CSIII breast cancer, and normal breast tissue was collected from women without invasive cancer. Seventy-eight genes were deregulated in CSIII tumors and 22 in CSII tumors when compared to normal tissue, and 20 of them were differentially expressed in both CSII and CSIII tumors. In addition, 58 genes were specifically altered in CSIII and expression of 6 of them was tested by real time RT-PCR in another cohort of patients with CSII or CSIII breast cancer and in women without cancer. Among these genes, MAX, KRT15 and S100A14, but not APOBEC3G or KRT19, were differentially expressed on both CSIII and CSII tumors as compared to normal tissue. Increased HMOX1 levels were detected only in CSIII tumors and may represent a molecular marker of this stage. A clear difference in gene expression pattern occurs at the normal-to-cancer transition; however, most of the differentially expressed genes are deregulated in tumors of both CS (II and III) compared to normal breast tissue.

Ras activation is associated with vitamin D receptor mRNA instability in HC11 mammary cells

HC11, a spontaneously immortalized murine mammary lineage maintains features of normal cells while HC11 H-ras transformed cells (HC11 ras) are tumorigenic. Ras transformation is associated with a lower Vitamin D receptor (VDR) mRNA content. Our goal was to investigate the mechanism underlying VDR mRNA differences between these cells. Although the VDR transcriptional rate measured by run-on assays did not differ between the cells, our data suggested a pos transcriptional mechanism involving higher VDR mRNA degradation in HC11 ras cells which was not due to mutations in its 3'-UTR region since sequences of mRNA obtained from HC11 and HC11 ras cells were identical. Treatment of HC11 ras cells with a farnesyltransferase inhibitor, which prevents ras activation, causing an enhancement of VDR mRNA levels, indicating an association between the ras signaling pathway and VDR mRNA instability. The present work suggests that the decreased mRNA levels in HC11 ras cells might in part be due to an early loss of stability.

Normal HC11 and ras-transformed mouse mammary cells are resistant to the antiproliferative effects of retinoic acid

The objective of the present study was to determine the effects of retinoic acid on the growth of the mouse mammary cells HC11 and HC11ras, which are a model for in vitro breast cancer progression. The expression of the two classes (RARs and RXRs) of retinoic acid receptor mRNAs was determined by Northern blot analysis. Receptor functional integrity was determined by testing whether RAR mRNA could be induced by retinoic acid. The effects of a 72-h exposure to 50 M 13-cis retinoic acid on HC11 and HC11ras cell proliferation and HC11 cell differentiation were investigated by flow cytometric cell cycle analysis, and by determination of -casein mRNA expression, respectively. The possibility that retinoic acid would induce the expression of the vitamin D receptor and synergize with vitamin D, a known inhibitor of HC11 cell growth, was also investigated. HC11 cells expressed higher mRNA levels of both RAR a and RAR g when compared to HC11ras cells. In contrast, RAR , as well as RXR a, and g expression was low in both HC11 and HC11ras cells. In addition, RAR mRNA was induced by retinoic acid treatment in both cells. In spite of these observations, no effects were seen on cell proliferation or differentiation upon exposure to retinoic acid. Neither vitamin D receptor induction nor synergy with vitamin D on growth inhibition was observed. We conclude that the RAR expression profile could be related to the transformed state in HC11ras cells and that the retinoic acid resistance observed merits further investigation.

Antiproliferative effects of 1,25-dihydroxyvitamin D3 on breast cells: a mini review

The hormone 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), the active form of vitamin D3, is an important regulator of calcium homeostasis, exerts antiproliferative effects on various cell systems and can induce differentiation in some kinds of hematopoietic cells. These effects are triggered by its receptor, vitamin D receptor (VDR), a phosphoprotein member of the nuclear receptor superfamily, which functions as a transcriptional factor. VDR binds as a heterodimer with retinoid X receptor (R X R) to hexameric repeats, characterized as vitamin D-responsive elements present in the regulatory region of target genes such as osteocalcin, osteopontin, calbindin-D28K, calbindin-D9K, p21WAF1/CIP1, TGF-beta2 and vitamin D 24-hydroxylase. Many factors such as glucocorticoids, estrogens, retinoids, proliferation rate and cell transformation can modulate VDR levels. VDR is expressed in mammary tissue and breast cancer cells, which are potential targets to hormone action. Besides having antiproliferative properties, vitamin D might also reduce the invasiveness of cancer cells and act as an anti-angiogenesis agent. All of these antitumoral features suggest that the properties of vitamin D could be explored for chemopreventive and therapeutic purposes in cancer. However, hypercalcemia is an undesirable side effect associated with pharmacological doses of 1,25-(OH)2D3. Some promising 1,25-(OH)2D3 analogs have been developed, which are less hypercalcemic in spite of being potent antiproliferative agents. They represent a new field of investigation.