Determining the frequency of pathogenic germline variants from exome sequencing in patients with castrate-resistant prostate cancer

OBJECTIVES

To determine the frequency of pathogenic inherited mutations in 157 select genes from patients with metastatic castrate-resistant prostate cancer (mCRPC).

DESIGN

Observational.

SETTING

Multisite US-based cohort.

PARTICIPANTS

Seventy-one adult male patients with histological confirmation of prostate cancer, and had progressive disease while on androgen deprivation therapy.

RESULTS

Twelve patients (17.4%) showed evidence of carrying pathogenic or likely pathogenic germline variants in the ATM, ATR, BRCA2, FANCL, MSR1, MUTYH, RB1, TSHR and WRN genes. All but one patient opted in to receive clinically actionable results at the time of study initiation. We also found that pathogenic germline BRCA2 variants appear to be enriched in mCRPC compared to familial prostate cancers.

CONCLUSIONS

Pathogenic variants in cancer-susceptibility genes are frequently observed in patients with mCRPC. A substantial proportion of patients with mCRPC or their family members would derive clinical utility from mutation screening.

TRIAL REGISTRATION NUMBER

NCT01953640; Results.

Mutational Landscapes of Sequential Prostate Metastases and Matched Patient Derived Xenografts during Enzalutamide Therapy

Developing patient derived models from individual tumors that capture the biological heterogeneity and mutation landscape in advanced prostate cancer is challenging, but essential for understanding tumor progression and delivery of personalized therapy in metastatic castrate resistant prostate cancer stage. To demonstrate the feasibility of developing patient derived xenograft models in this stage, we present a case study wherein xenografts were derived from cancer metastases in a patient progressing on androgen deprivation therapy and prior to initiating pre-chemotherapy enzalutamide treatment. Tissue biopsies from a metastatic rib lesion were obtained for sequencing before and after initiating enzalutamide treatment over a twelve-week period and also implanted subcutaneously as well as under the renal capsule in immuno-deficient mice. The genome and transcriptome landscapes of xenografts and the original patient tumor tissues were compared by performing whole exome and transcriptome sequencing of the metastatic tumor tissues and the xenografts at both time points. After comparing the somatic mutations, copy number variations, gene fusions and gene expression we found that the patient's genomic and transcriptomic alterations were preserved in the patient derived xenografts with high fidelity. These xenograft models provide an opportunity for predicting efficacy of existing and potentially novel drugs that is based on individual metastatic tumor expression signature and molecular pharmacology for delivery of precision medicine.

Frequency of diagnosis of cancer or high-risk lesion at operation for pathologic nipple discharge

BACKGROUND

Pathologic nipple discharge is managed customarily with diagnostic subareolar duct excision. We evaluated for features predictive of malignancy to identify cases where operation might be avoided.

METHODS

We studied 311 consecutive subareolar duct excisions for pathologic nipple discharge from January 2008 to July 2014. χ(2) tests were used to test for associations with final pathology.

RESULTS

In 27 cases, cancer was diagnosed preoperatively. Among the remaining 284, 26 (9%) were diagnosed with cancer and 8 (3%) with atypia at operation. At greatest risk of upstage to cancer were patients with prior ipsilateral breast cancer (3/8; 38%), BRCA mutation (2/3; 67%) or atypia on core needle biopsy (CNB; 3/8 [38%]). Excluding these patients lowered cancer and atypia upstages (7% [18/265] and 3% [7/265]), with bloody (versus serous) discharge (P = .001), and focal imaging abnormality (P = .02), the strongest risk factors. Serous discharge and either normal imaging or a benign CNB had a 1.3% cancer upstage rate.

CONCLUSION

Despite contemporary imaging, pathologic nipple discharge upstage rates to malignancy and atypia remain high, especially with prior ipsilateral breast cancer, BRCA mutation, or atypia on CNB. Absent these risk factors, patients with serous discharge and a benign CNB or normal imaging (cancer risk <2%) may be considered for nonoperative management.

Abstract 3304: Role of Vascular Endothelial Growth Factor C in promoting radioresistance of prostate cancer

Radiotherapy is an important treatment regimen for prostate cancer. We have shown that the lymphangiogenic growth factor, Vascular Endothelial Growth Factor C (VEGF-C), induces docetaxel resistance and autophagy in prostate cancer (Muders et al., Cancer Res 2009 and Stanton et al., Cancer Res 2013). In this study we have evaluated the role of VEGF-C and VEGF-C induced autophagy in radioresistance of prostate cancer using cell culture experiments and human tissue samples.

The human prostate carcinoma cell lines PC-3, LNCaP and DU145 were used in these cell culture experiments. Clonogenic survival of prostate cancer cells, after RNA interference (RNAi) of VEGF-C, autophagy related gene 5 (ATG5), and after addition of recombinant human VEGF-C following irradiation therapy, was evaluated. Autophagic flux was tested after ionizing irradiation using a Light-Chain-3 II immunoblot. To confirm our in vitro findings, human tissues of patients who underwent radical prostatectomy and adjuvant radiotherapy at Mayo Clinic were evaluated for VEGF-C expression. The quantity and intensity of VEGF-C staining was evaluated by two pathologists independently and correlated with biochemical relapse free survival (BRFS). The follow-up time is up to 23 years after radiotherapy. Multivariate Cox analysis was performed.

VEGF-C levels correlated with a significantly higher radioresistance in colony formation assays and human tissue samples by multivariate analysis. The risk of biochemical recurrence increased 2.8 fold (95% confidence interval: 1.109 to 7.237; p = 0.03) when VEGF-C was highly expressed in prostatectomy patients with adjuvant radiotherapy. In line with our studies on autophagy in VEGF-C mediated docetaxel resistance of prostate cancer, autophagic flux was reduced after VEGF-C depletion during radiation. Interestingly, RNAi for ATG5 showed no effect on radiosensitivity which suggests that the decrease in autophagic flux after VEGF-C depletion is not responsible for the increased radiosensitivity.

We conclude that VEGF-C is an important mediator of radiotherapy resistance in prostate cancer. In contrast to our published results on chemotherapy resistance, VEGF-C induced autophagy appears to be less important for resistance against ionizing radiation. Other VEGF-C dependent mechanisms for therapy resistance are under investigation.

Citation Format: Steffi Haberlau, Pia Hönscheid, Rafael E. Jimenez, Gustavo B. Baretton, Donald J. Tindall, Mechthild Krause, Kaustubh Datta, Michael H. Muders. Role of Vascular Endothelial Growth Factor C in promoting radioresistance of prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3304. doi:10.1158/1538-7445.AM2015-3304

Feasibility analysis of pathology and genetic yield from a prospective trial of tissue biopsies in metastatic castrate-resistant prostate cancer (mCRPC)

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Background: Evaluating tumor specific pathologic and genetic profiles in mCRPC stage is difficult due to the limited availability of mCRPC tissue. We describe findings from a prospective cohort study performed to obtain concomitant histopathology and genetic information in mCRPC. Methods: Patients with mCRPC initiating abiraterone acetate therapy underwent 2 serial (3 months apart) metastatic (met) site needle core biopsies (NCB1/2). Bone lesions were biopsied using 11-13G core needles and 18G core biopsy devices were used for non-osseous masses. Up to 4 cores were obtained at each biopsy with the 1st core (S1) sent for DNA sequencing, the 2nd (S2) for RNA sequencing, and the 3rd/4th (X3, X4) submitted for xenograft implantation. From each, 1-2 mm segments were separated and formalin-fixed for histopathologic examination (HPE). Results: A total of 54 patients, enrolled between June 2013 and July 2014, underwent 94 NCB (54 NCB1, 40 NCB2), rendering a total of 259 samples (94 S1; 75 S2; 59 X3 and 31 X4) of which 85 (32%) were positive (pos) for tumor by HPE. Positivity for tumor in S1, S2, X3, and X4 cores was 42%, 33%, 22%, and 19%, respectively. At least one core pos for met tumor was observed in 62% NCB1 and 52% NCB2 (overall 52/94; 56%). Met sites biopsied include bone (71), lymph nodes (18), liver (3), penile (1) and pelvic (1) soft tissues. HPE revealed met adenocarcinoma in 44/52, and poorly differentiated carcinoma in 8/52. Gleason grade applied to the met ranged from 3+4 to 5+5. 45/85 pos samples (53%) had > 50% tumor cellularity. Pos NCB in bone lesions was observed in 23/71 (32%), compared to 17/23 (73%) of non-bone sites (p=.0004). 85 S1 samples yielded DNA material, of which 66 (77%) had ≥10% tumoral DNA. 24 cases with negative HPE had ≥10% tumoral DNA; 7 cases with pos HPE had <10 tumoral DNA. In all, 76/94 (81%) NCB yielded tumor material either by HPE or DNA analysis. Conclusions: NCB of mCRPC is feasible and provides adequate tissue for pursuing HPE and sequencing studies. HPE of extracted material correlates with DNA sequencing data and provides complementary information on tumor features. Bone lesions yield significantly less tumoral material than non-osseous sites.

Androgen receptor (AR) based biomarker association with response to abiraterone acetate/prednisone (AA/P) in metastatic castrate resistant prostate cancer (mCRPC)

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Background: AA/P is an FDA approved treatment for mCRPC. Since markers of early resistance to AA/P are unknown, we report initial findings of androgen receptor (AR) based associations with short term (12 week) progression on AA/P. Methods: mCRPC stage patients (pts) initiating pre-chemotherapy AA/P underwent metastatic site biopsies at baseline (pre AA/P) and after 12 weeks. Baseline somatic whole exome DNA, tumor gene expression for AR full length (ARFL), AR splice variant 7 (ARV7) and ARV7/ARFL ratios were compared in progessors versus non-progressors. Progression at or within 12 weeks of AA/P therapy was defined as death or disease progression by PCWG2 “composite progression (CP)” and/or “radiographic progression” endpoints. Wilcoxon rank-sum tests were used to test for differences in the two groups for comparing ARFL, ARV7 expressions and ARV7/ARFL ratios and chi square tests were used for differences in copy number variation. Results: Between 1/2013 and 6/2014, 59 pts were enrolled of which 44 have disease assessment data at the12-week time point. CP was observed in 17/44 patients. DNA seq and clinical data was available for 42/44 pts. Using radiographic progression at 12 weeks, AR Amplification/Gain was observed in 20/26 non-progressors (13 with Amplification) and in 9/16 progressors (P-value = 0.19; OR 2.5). ARFL and ARV7 gene expressions in both groups is provided in table. Conclusions: A trend towards higher ARV7/ARFL gene expression ratio in metastases was observed with early progression on AA/P. AR gain/amplification is observed less often in pts with early progression. Validation of these findings is on-going in this prospective trial. Clinical trial information: NCT# 01953640. [Table: see text]

Predicting the biologic classification of phyllodes tumors from preoperative core needle biopsy and imaging findings

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Background: Phyllodes tumors (PT) are rare breast neoplasms confounding their systematic study and evidence-based management guidelines. There is little data on the sensitivity of preoperative core needle biopsy (CNB) and imaging findings in establishing a correct preoperative diagnosis. We undertook this study to evaluate the sensitivity of CNB histologic findings and imaging findings in preoperatively categorizing tumors as benign or borderline/malignant. Methods: We identified 47 patients who underwent surgical resection of a PT at our institution after a preoperative CNB between 6/2000-3/2012. Statistical analysis utilized Wilcoxon rank-sum, chi-square or Fisher’s exact tests, and 95% confidence intervals (CI) are reported. Results: 30 patients had a final diagnosis of benign and 17 of borderline/malignant PT. The latter were significantly more often palpable (76.5% vs 36.7%, p=0.01). No other clinical or radiologic feature predicted borderline/malignant subtype, although irregular shape on US was suggestive (70.6% vs 44.8%, p= 0.09). CNB diagnosis by tumor type is summarized in the table. No benign PT had ≥10 mitoses, necrosis or marked stromal atypia on CNB. No case with absent mitoses on preoperative CNB was a borderline/malignant PT; however 77% of benign PT did exhibit mitoses on CNB. Sensitivity of CNB for PT overall was 48.9% (95% CI: 35.3-62.8%) while it was 40% (24.6-57.7%) for benign PT and 17.6% (6.2-41.0%) for borderline/malignant PT. Conclusions: Marked stromal atypia, ≥10 mitoses and necrosis were rare on CNB, but suggestive of malignancy. No imaging or histology feature reliably distinguished between tumor types. Over one-third of borderline/malignant PT had a preoperative CNB diagnosis of fibroadenoma or cellular fibroepithelial lesion emphasizing the low sensitivity of CNB and the need for judicious consideration of definitive surgical excision. [Table: see text]

Surgical treatment of borderline and malignant phyllodes tumors: the effect of the extent of resection and tumor characteristics on patient outcome

INTRODUCTION

Malignant phyllodes tumors are rare fibroepithelial breast neoplasms. Appropriate surgical management remains a subject of debate. The purpose of our study was to define optimal surgical treatment and to identify factors associated with outcome.

METHODS

After confirmatory pathology review, we identified 67 patients with borderline (n = 15) and malignant (n = 52) phyllodes tumors treated at our institution between 1971 and 2008. We used Cox proportional hazards models to evaluate associations between treatment, patient and tumor characteristics, and disease-free (DFS) and cancer-specific survival (CSS).

RESULTS

Median patient age was 47 years. For 32 patients, definitive surgical treatment was wide local excision (WLE): 27 with margins ≥1 cm and 5 with margins <1 cm. Thirty-five underwent mastectomy. Two patients received radiotherapy after WLE and two after mastectomy with microscopically positive margins. After 10 years median follow-up, 16 patients (24 %) recurred locally (8 postmastectomy and 8 after WLE). Treatment type and margin extent did not impact local recurrence. Fifteen patients (22 %) developed distant disease. Overall 5-year DFS was 67.9 % and CSS 80.1 %. Tumor size >5 cm, mitotic rate ≥10/10 HPF, stromal overgrowth and cellularity (all p < 0.05) predicted DFS, whereas CSS was associated with the latter three variables. CSS was diminished for mastectomy patients who were significantly more likely to harbor tumors with adverse features.

CONCLUSIONS

With long-term follow-up, extent of surgical resection did not affect DFS for patients with borderline and malignant phyllodes tumors. Tumor features, most notably stromal overgrowth, were predictive of recurrence and survival, suggesting these high-risk patients may benefit from additional therapeutic strategies.

Amyloidosis of the breast: predominantly AL type and over half have concurrent breast hematologic disorders

Amyloidosis is a disorder characterized by extracellular deposition of proteins in an abnormal fibrillar configuration. Amyloidosis can be localized or systemic and may affect any organ. Breast involvement by amyloidosis has rarely been reported. In this study, we described the characteristics of 40 cases of breast amyloidosis that were reviewed at the Division of Anatomic Pathology at Mayo Clinic from 1995 to 2011. The cohort included 39 women and 1 man with a mean age of 60 years. The type of amyloidosis, determined by immunohistochemistry or mass spectrometry-based proteomics in 26 patients, was immunoglobulin-associated in all cases (AL-kappa type in 15 (58%) cases, AL-lambda in 10 (38%) and mixed heavy and light chains (AH/AL) in 1 (4%) case). Mass spectrometry-based proteomics was able to determine the type of amyloidosis in 95% of cases tested compared with 69% of cases by immunohistochemistry. In addition to amyloidosis, the breast biopsy showed a hematologic disorder in 55% of cases, most commonly MALT lymphoma. One patient had concurrent intraductal carcinoma, but none had invasive carcinoma. Of the 15 patients seen in our institution, 53% had localized amyloidosis and 47% had extramammary amyloid involvement, which was diagnosed before breast amyloidosis in most patients. M-spike was detected in the blood in 62%. After a median follow-up of 33.5 months in 12 patients, 5 died, mostly of complications of lymphoma or leukemia. In conclusion, our findings indicate that breast amyloidosis is of the AL type in the vast majority of patients (usually kappa). It is associated with systemic amyloidosis in close to half of patients and with hematologic malignancy in the breast in over half of patients. Therefore, further work up to rule out hematologic malignancy and/or systemic amyloidosis is recommended. Mass spectrometry-based proteomics is superior to immunohistochemistry for typing of breast amyloidosis.

Global methylation profiling for risk prediction of prostate cancer

PURPOSE

The aim of this study was to investigate the promoter hypermethylation as diagnostic markers to detect malignant prostate cells and as prognostic markers to predict the clinical recurrence of prostate cancer.

EXPERIMENTAL DESIGN

DNA was isolated from prostate cancer and normal adjacent tissues. After bisulfite conversion, methylation of 14,495 genes was evaluated using the Methylation27 microarrays in 238 prostate tissues. We analyzed methylation profiles in four different groups: (i) tumor (n = 198) versus matched normal tissues (n = 40), (ii) recurrence (n = 123) versus nonrecurrence (n = 75), (iii) clinical recurrence (n = 80) versus biochemical recurrence (n = 43), and (iv) systemic recurrence (n = 36) versus local recurrence (n = 44). Group 1, 2, 3, and 4 genes signifying biomarkers for diagnosis, prediction of recurrence, clinical recurrence, and systemic progression were determined. Univariate and multivariate analyses were conducted to predict risk of recurrence. We validated the methylation of genes in 20 independent tissues representing each group by pyrosequencing.

RESULTS

Microarray analysis revealed significant methylation of genes in four different groups of prostate cancer tissues. The sensitivity and specificity of methylation for 25 genes from 1, 2, and 4 groups and 7 from group 3 were shown. Validation of genes by pyrosequencing from group 1 (GSTP1, HIF3A, HAAO, and RARβ), group 2 (CRIP1, FLNC, RASGRF2, RUNX3, and HS3ST2), group 3 (PHLDA3, RASGRF2, and TNFRSF10D), and group 4 (BCL11B, POU3F3, and RASGRF2) confirmed the microarray results.

CONCLUSIONS

Our study provides a global assessment of DNA methylation in prostate cancer and identifies the significance of genes as diagnostic and progression biomarkers of prostate cancer.

Coexistence of Cushing syndrome from functional adrenal adenoma and Addison disease from immune-mediated adrenalitis

A 56-year-old woman presented with an incidental adrenal adenoma and physical examination findings that included moderate obesity, a slight cervicothoracic fat pad ("buffalo hump"), increased supraclavicular fat pads, and white abdominal striae. Biochemical workup revealed elevated levels of 24-hour urinary free cortisol but normal serum morning cortisol and suppressed levels of corticotropin, suggestive of adrenal-dependent Cushing syndrome. The resected adrenal gland revealed macronodular cortical hyperplasia with a dominant nodule. Other findings included an absent cortisol response to corticotropin stimulation, presence of serum anti-21-hydroxylase antibodies, and mononuclear cell infiltration--consistent with adrenalitis. The findings represent, to the authors' knowledge, the first known case of a patient with coexistent functional cortisol-secreting macronodular adrenal tumor resulting in Cushing syndrome and immune-mediated adrenalitis resulting in Addison disease.

Reprogramming of the tumour microenvironment by stromal PTEN-regulated miR-320

Phosphatase and tensin homolog deleted on chromosome ten (Pten) in stromal fibroblasts suppresses epithelial mammary tumors, but the underlying molecular mechanisms remain unknown. Using proteomic and expression profiling, we show that Pten loss from mammary stromal fibroblasts activates an oncogenic secretome that orchestrates the transcriptional reprogramming of other cell types in the microenvironment. Downregulation of miR-320 and upregulation of one of its direct targets, ETS2, are critical events in Pten-deleted stromal fibroblasts responsible for inducing this oncogenic secretome, which in turn promotes tumor angiogenesis and tumor cell invasion. Expression of the Pten-miR-320-Ets2 regulated secretome distinguished human normal breast stroma from tumor stroma and robustly correlated with recurrence in breast cancer patients. This work reveals miR-320 as a critical component of the Pten tumor suppressor axis that acts in stromal fibroblasts to reprogram the tumor microenvironment and curtail tumor progression.

Microarray analysis of genes associated with cell surface NIS protein levels in breast cancer

Background

Na⁺/I^- symporter (NIS)-mediated iodide uptake allows radioiodine therapy for thyroid cancer. NIS is also expressed in breast tumors, raising potential for radionuclide therapy of breast cancer. However, NIS expression in most breast cancers is low and may not be sufficient for radionuclide therapy. We aimed to identify biomarkers associated with NIS expression such that mechanisms underlying NIS modulation in human breast tumors may be elucidated.

Methods

Published oligonucleotide microarray data within the National Center for Biotechnology Information Gene Expression Omnibus database were analyzed to identify gene expression tightly correlated with NIS mRNA level among human breast tumors. NIS immunostaining was performed in a tissue microarray composed of 28 human breast tumors which had corresponding oligonucleotide microarray data available for each tumor such that gene expression associated with cell surface NIS protein level could be identified.

Results and Discussion

NIS mRNA levels do not vary among breast tumors or when compared to normal breast tissues when detected by Affymetrix oligonucleotide microarray platforms. Cell surface NIS protein levels are much more variable than their corresponding NIS mRNA levels. Despite a limited number of breast tumors examined, our analysis identified cysteinyl-tRNA synthetase as a biomarker that is highly associated with cell surface NIS protein levels in the ER-positive breast cancer subtype.

Conclusions

Further investigation on genes associated with cell surface NIS protein levels within each breast cancer molecular subtype may lead to novel targets for selectively increasing NIS expression/function in a subset of breast cancers patients.

Ultrasound-guided diagnostic breast biopsy methodology: retrospective comparison of the 8-gauge vacuum-assisted biopsy approach versus the spring-loaded 14-gauge core biopsy approach

Background

Ultrasound-guided diagnostic breast biopsy technology represents the current standard of care for the evaluation of indeterminate and suspicious lesions seen on diagnostic breast ultrasound. Yet, there remains much debate as to which particular method of ultrasound-guided diagnostic breast biopsy provides the most accurate and optimal diagnostic information. The aim of the current study was to compare and contrast the 8-gauge vacuum-assisted biopsy approach and the spring-loaded 14-gauge core biopsy approach.

Methods

A retrospective analysis was done of all ultrasound-guided diagnostic breast biopsy procedures performed by either the 8-gauge vacuum-assisted biopsy approach or the spring-loaded 14-gauge core biopsy approach by a single surgeon from July 2001 through June 2009.

Results

Among 1443 ultrasound-guided diagnostic breast biopsy procedures performed, 724 (50.2%) were by the 8-gauge vacuum-assisted biopsy technique and 719 (49.8%) were by the spring-loaded 14-gauge core biopsy technique. The total number of false negative cases (i.e., benign findings instead of invasive breast carcinoma) was significantly greater (P = 0.008) in the spring-loaded 14-gauge core biopsy group (8/681, 1.2%) as compared to in the 8-gauge vacuum-assisted biopsy group (0/652, 0%), with an overall false negative rate of 2.1% (8/386) for the spring-loaded 14-gauge core biopsy group as compared to 0% (0/148) for the 8-gauge vacuum-assisted biopsy group. Significantly more (P < 0.001) patients in the spring-loaded 14-gauge core biopsy group (81/719, 11.3%) than in the 8-gauge vacuum-assisted biopsy group (18/724, 2.5%) were recommended for further diagnostic surgical removal of additional tissue from the same anatomical site of the affected breast in an immediate fashion for indeterminate/inconclusive findings seen on the original ultrasound-guided diagnostic breast biopsy procedure. Significantly more (P < 0.001) patients in the spring-loaded 14-gauge core biopsy group (54/719, 7.5%) than in the 8-gauge vacuum-assisted biopsy group (9/724, 1.2%) personally requested further diagnostic surgical removal of additional tissue from the same anatomical site of the affected breast in an immediate fashion for a benign finding seen on the original ultrasound-guided diagnostic breast biopsy procedure.

Conclusions

In appropriately selected cases, the 8-gauge vacuum-assisted biopsy approach appears to be advantageous to the spring-loaded 14-gauge core biopsy approach for providing the most accurate and optimal diagnostic information.

Immunohistochemical analysis in a morphologic spectrum of urachal epithelial neoplasms: diagnostic implications and pitfalls

The vast majority of urachal epithelial neoplasms are adenocarcinomas with several described morphologic subtypes that include both enteric and nonenteric histologies. Adenocarcinoma from several other primaries may mimic any of these urachal adenocarcinoma subtypes in the bladder or at distant sites. However, data regarding the immunohistochemical profile of urachal carcinoma are limited, let alone its correlation with the different histologic subtypes that may have implications in the differential diagnostic workup with their morphologic mimics. Herein, we performed an immunohistochemical analysis in a broad spectrum of 39 urachal epithelial neoplasms (34 adenocarcinomas, 1 urothelial carcinoma, and 4 noninvasive mucinous cystic tumors), 13 urachal remnants, and 6 secondary colonic adenocarcinomas of the bladder, using an antibody panel that included novel and traditional gastrointestinal tract-associated markers. Expression levels of p63, CK7, CK20, CDX2, nuclear β-catenin, claudin-18, and Reg IV in urachal adenocarcinoma were as follows: 3%, 50%, 100%, 85%, 6%, 53%, and 85%. In urachal adenocarcinoma subtypes, expression levels of CDX2, nuclear β-catenin, claudin-18, and Reg IV were as follows: mucinous (8/8, 0/8, 6/8, 8/8), enteric (10/11, 1/11, 3/11, 8/11), not otherwise specified (5/7, 0/7, 3/7, 5/7), and signet ring cell (4/6, 0/6, 4/6, 6/6) type. All urachal adenocarcinomas had membrano-cytoplasmic β-catenin staining and only 2 tumors had nuclear localization that were focal to moderate, in contrast to secondary colonic adenocarcinoma of the bladder, which mostly had both membrano-cytoplasmic and nuclear positivity. Claudin-18 positivity was observed only in frankly malignant tumors and not in noninvasive urachal tumors and urachal remnants. Reg IV expression seemed to be related to mucin production, which was often diffuse in mucinous and signet ring cell subtypes and focal in enteric subtype, with goblet cell-like reactivity similar to secondary colonic adenocarcinoma. p63 expression was present in urothelial urachal remnants (3/3) and contrasted with CDX2 expression seen in glandular (5/6) and mixed urothelial/glandular remnants (2/4). Thus, this study showed that CDX2 is expressed by urachal remnants of glandular type, noninvasive urachal mucinous cystic tumors and urachal adenocarcinomas, and can be diffuse in urachal adenocarcinomas, even without the classic enteric morphology. Nuclear localization of β-catenin can rarely occur in urachal adenocarcinoma; however, diffuse nuclear reactivity argues against its diagnosis. The novel gastrointestinal tract markers claudin-18 and Reg IV are both expressed in urachal adenocarcinoma, including in signet ring cell carcinoma, and thus refutes the suggested specificity for gastrointestinal tract signet ring cell carcinomas. An immunohistochemical panel that includes β-catenin and CK7 may have value in differentiating urachal adenocarcinoma of enteric morphology from colonic adenocarcinoma. Overall, this study suggests that the different morphologic presentations of urachal adenocarcinomas have a relatively similar or overlapping immunophenotype. Knowledge of the similarity in immunostaining to its different morphologic mimics may help avoid misdiagnosis in urachal adenocarcinoma.

Abstract 1659: Targeting SIAH2-dependent proteolysis downstream of the HER2/EGFR/RAS signaling pathway to inhibit tumorigenesis and metastasis of highly invasive human breast cancer

Breast cancer is the most common form of cancer diagnosed and the second leading cause of cancer death among women in the United States. Cancer metastases are the major cause of morbidity and mortality among breast cancer patients. The central importance of the HER2/RAS signaling pathway has been well established in promoting tumor growth, invasion and metastasis of human breast cancer. Even though oncogenic K-RAS mutations are rare in breast cancer, activation of the growth-promoting ERBB/RAS pathway has been consistently documented in high-grade breast tumors. As such, novel approaches to inhibit activated HER2/RAS signals constitute important measures to block tumor growth and metastasis in mammary tumors. In this study, instead of targeting an upstream signaling component such as HER2/EGFR/RAS, we targeted the most downstream signaling module identified in the ERBB/RAS pathway – the SIAH proteolytic machinery. SIAH is an evolutionarily conserved RING E3 ligase that is a critical “gatekeeper” required for RAS signal transduction in human cancer cells. SIAH is specifically expressed in tumor cells in 120 human breast cancer patients examined so far. The increased SIAH expression is correlated with increased grades and aggressiveness of human breast cancer. We asked whether inhibiting the gatekeeper function of SIAH would be effective in blocking mammary tumorigenesis and metastasis in human breast cancer. Our results indicated that SIAH2-deficiency successfully abolished tumor growth of three breast cancer cell lines (MDA-MB-231, MDA-MB-435 and MDA-MB-468) in soft agar assays as well as in athymic nude mice. Importantly, by inhibiting SIAH2 function in highly aggressive human breast cancer cells, we are able to completely block tumorigenesis and metastasis of two highly invasive and metastatic human breast cancer cell lines (MDA-MB-231 and MDA-MB-435). These results suggest that SIAH2 may be an attractive and new drug target for novel breast cancer therapy. Developing anti-SIAH molecules will aid in expanding our arsenal of effective anticancer therapies. By attacking the growth-promoting HER2/EGFR/RAS pathway at multiple signaling modules simultaneously – a multi-pronged synergistic inhibition at upstream (HER2/EGFR membrane receptors), midstream (RAS/RAF/MEK/mTOR) and downstream (SIAH E3 ligase) signaling modules in the HER2/EGFR/RAS pathway in parallel, we may be in a position to halt the genesis, progression and metastasis of human breast cancer. Thus, SIAH-dependent proteolysis may be an Achilles heel for breast cancer. SIAH inhibition may represent an innovative and logical way to inhibit HER2/EGFR/K-RAS activation, alleviate tumor burdens, halt cancer metastasis, and improve the efficacy for the future treatment of breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1659. doi:10.1158/1538-7445.AM2011-1659

Abstract P6-15-14: Inhibit SIAH E3 Ligase, a Downstream Signaling Module Required for the HER2/EGFR/RAS Signal Transduction, To Block Tumorigenesis and Metastasis of Highly Invasive Human Breast Cancers

The central importance of the HER2/Neu/EGFR/RAS signaling pathway has been well established in the growth, invasion and metastasis of human breast cancer, even though oncogenic RAS mutations are rare in breast cancer, activation of the tumor-promoting ERBB/RAS/MEK/MAPK pathway has been consistently documented in high-grade breast tumors. As such, novel approaches to inhibit activated ERBB/RAS signals constitute important measures to block tumor growth and metastasis in mammary tumors. In this study, instead of targeting an upstream signaling component such as HER2/EGFR/RAS, we targeted the most downstream signaling module identified in the RAS pathway — the SIAH proteolytic machinery. SIAH is an evolutionarily conserved RING E3 ligase that is a critical “gatekeeper” required for RAS signal transduction in human cancer cells. SIAH is specifically expressed in tumor cells in 120 human breast cancer patients examined so far. The increased SIAH expression is correlated with increased grades and aggressiveness of human breast cancer. We then asked whether inhibiting the gatekeeper function of SIAH would be effective in blocking mammary tumorigenesis and metastasis in human breast cancer. Our results indicated that SIAH2-deficiency successfully abolished tumor growth of three breast cancer cell lines (MDA-MB-231, MDA-MB-435 and MDA-MB-468) in soft agar assays as well as in athymic nude mice. Importantly, by inhibiting SIAH2 function in highly aggressive human breast cancer cells, we are able to completely block tumorigenesis and metastasis of two highly invasive and metastatic human breast cancer cell lines (MDA-MB-231 and MDA-MB-435). These findings suggest that SIAH2 may be an attractive new therapeutic target for novel breast cancer therapy and developing anti-SIAH molecules will aid in expanding our arsenal of effective anticancer therapies. More effective breast cancer treatments may be obtained by multi-pronged synergistic inhibitions at upstream (HER2/EGFR membrane receptors), midstream (RAS/RAF/MEK/mTOR) and downstream (SIAH E3 ligase) signaling modules in the HER2/EGFR/RAS pathway in parallel. Thus, by attacking the growth-promoting ERBB/RAS pathway at multiple signaling modules simultaneously, we may be in a great position to halt the genesis, progression and metastasis of human breast cancer.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-15-14.