The eyes don't see, what the mind doesn't know

Introduction/Objective

Calcifying fibrous tumor is a rare benign mesenchymal neoplasm. The etiology and pathogenesis of this tumor are uncertain. It has wide anatomical distribution. The tumor is most commonly found in the soft tissues of the extremities in younger individuals. However, in middle aged patients it tends to affect the visceral locations more commonly. In visceral location it can mimic aggressive lesions clinically. The purpose of this report is to describe a case of calcifying fibrous tumor in a 71-year-old female with a history of breast carcinoma who was found to have an incidental small bowel mass on her follow up. Clinically and radiologically and the main diagnostic consideration were metastatic disease and gastrointestinal stromal tumor.

Methods/Case Report

The patient underwent an open small bowel resection, and a 6.5 cm segment of small bowel was sent to pathology. Grossly, a 2.0 cm tan-pink smooth round submucosal polyploid mass protruding into the lumen, mimicking gastrointestinal stromal tumor was identified. The tumor was hard and serially sectioned to reveal a white, calcified cut surface. Microscopically, the tumor appeared hypocellular and composed of scant spindle cells embedded in a dense, hyalinized and calcified, collagenous stroma. Immunohistochemical stains for pan cytokeratin, DOG1, desmin, S100, CD34, and MUC4 were negative, and diagnosis of calcifying fibrous tumor was rendered.

Results (if a Case Study enter NA)

NA.

Conclusion

This case highlights the importance of knowledge of rare entities in providing accurate diagnosis for lesions that can clinically mimic common tumors.

Elevated NRAS expression during DCIS is a potential driver for progression to basal-like properties and local invasiveness

BACKGROUND

Ductal carcinoma in situ (DCIS) is the most common type of in situ premalignant breast cancers. What drives DCIS to invasive breast cancer is unclear. Basal-like invasive breast cancers are aggressive. We have previously shown that NRAS is highly expressed selectively in basal-like subtypes of invasive breast cancers and can promote their growth and progression. In this study, we investigated whether NRAS expression at the DCIS stage can control transition from luminal DCIS to basal-like invasive breast cancers.

METHODS

Wilcoxon rank-sum test was performed to assess expression of NRAS in DCIS compared to invasive breast tumors in patients. NRAS mRNA levels were also determined by fluorescence in situ hybridization in patient tumor microarrays (TMAs) with concurrent normal, DCIS, and invasive breast cancer, and association of NRAS mRNA levels with DCIS and invasive breast cancer was assessed by paired Wilcoxon signed-rank test. Pearson's correlation was calculated between NRAS mRNA levels and basal biomarkers in the TMAs, as well as in patient datasets. RNA-seq data were generated in cell lines, and unsupervised hierarchical clustering was performed after combining with RNA-seq data from a previously published patient cohort.

RESULTS

Invasive breast cancers showed higher NRAS mRNA levels compared to DCIS samples. These NRAShigh lesions were also enriched with basal-like features, such as basal gene expression signatures, lower ER, and higher p53 protein and Ki67 levels. We have shown previously that NRAS drives aggressive features in DCIS-like and basal-like SUM102PT cells. Here, we found that NRAS-silencing induced a shift to a luminal gene expression pattern. Conversely, NRAS overexpression in the luminal DCIS SUM225 cells induced a basal-like gene expression pattern, as well as an epithelial-to-mesenchymal transition signature. Furthermore, these cells formed disorganized mammospheres containing cell masses with an apparent reduction in adhesion.

CONCLUSIONS

These data suggest that elevated NRAS levels in DCIS are not only a marker but can also control the emergence of basal-like features leading to more aggressive tumor activity, thus supporting the therapeutic hypothesis that targeting NRAS and/or downstream pathways may block disease progression for a subset of DCIS patients with high NRAS.

Abstract 2979: ElevatedNRASexpression as a potential driver of DCIS progression to basal-like invasive breast cancer

Background: Ductal carcinoma in situ (DCIS) is the most common type of in situ premalignant breast cancers. What drives a subset of luminal DCIS to transition to basal invasive breast cancers is unclear. Basal-like invasive breast cancers are aggressive and associated with the shortest overall survival and time to distant metastasis. We have previously shown that N-Ras is highly expressed selectively in the basal-like subtypes of invasive breast cancers and can promote their growth and progression. In this study, we investigated whether NRAS expression at the DCIS stage can control transition from luminal DCIS to basal-like invasive breast cancers.

Methods: Wilcoxon rank-sum test was conducted to assess the relative expression of NRAS in DCIS compared to invasive breast cancers in a patient cohort (GSE59248). NRAS levels were also determined by fluorescence in situ hybridization (FISH) in a collection of 21 patient tumor microarrays (TMAs) with concurrent normal, DCIS, and invasive breast cancer, and NRAS’s association with DCIS and invasive breast cancer was assessed by Wilcoxon signed rank test. How NRAS levels correlated with basal biomarkers in the TMAs, as well as in patient datasets GSE59248 and GSE3369 was determined by Pearson correlation. Gene expression changes in cell line were assessed by RNA-seq.

Results: Invasive breast cancers showed higher NRAS mRNA levels, as compared to DCIS samples. These NRAShigh lesions were also enriched with basal-like features, such as basal gene expression signature, lower ER, higher p53 protein levels, and higher Ki67 levels. We have shown previously that N-Ras is a driver for tumor growth in SUM102 cells, which is a DCIS-like cell line model displaying basal-like features. Here we found that NRAS-silencing in these cells induced a shift to a luminal gene expression pattern as determined by PAM50.

Conclusions: These data suggest that the rise of N-RAS levels in DCIS can not only mark but also control the emergence of basal-like features leading to more aggressive tumor activities. Targeting N-Ras and/or its downstream pathway may prevent the emergence of basal invasive breast cancers.

Citation Format: Ze-yi Zheng, Hanan Elsarraj, Yang Hong, Jonathan T. Lei, Meenakshi Anurag, Yichao Shen, Flora Lo, Long Feng, Zifan Zhao, Xiang H. Zhang, Fariba Behbod, Eric C. Chang. ElevatedNRASexpression as a potential driver of DCIS progression to basal-like invasive breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2979.

Calcifying fibrous tumor

Calcifying fibrous tumor is a rare benign mesenchymal neoplasm. The etiology and pathogenesis of this tumor are uncertain. It has wide anatomical distribution. The tumor is most commonly found in the soft tissues of the extremities in younger individuals. However, in middle-aged patients, it tends to affect the visceral locations more commonly. In visceral location, it can mimic aggressive lesions clinically. The purpose of this report is to describe a case of calcifying fibrous tumor in a 71-year-old female with a history of breast carcinoma who was found to have an incidental small bowel mass on her follow-up. Clinically and radiologically, the mass was suspicious for either metastatic disease or gastrointestinal stromal tumor.

The patient underwent open small bowel resection, and a 6.5 cm segment of the small bowel was sent to pathology. Grossly, a 2.0 cm tan-pink smooth round submucosal polyploid mass protruding into the lumen, mimicking a gastrointestinal stromal tumor, was identified. The tumor was hard and serially sectioned to reveal a white, calcified cut surface. Microscopically, the tumor appeared hypocellular and composed of scant spindle cells embedded in a dense, hyalinized and calcified collagenous stroma. Immunohistochemical stains for pan-cytokeratin, DOG1, desmin, S100, CD34, and MUC4 were negative, and a diagnosis of the calcifying fibrous tumor was rendered.

This case provides a rare gross specimen image of calcifying fibrous tumor and highlights the importance of knowledge of rare entities in providing an accurate diagnosis for entities that can mimic other lesions.

Abstract PS19-15: N-RAS as a marker for DCIS progression

Background: Ductal carcinoma in situ (DCIS) is a key premalignant stage. Approximately 50% of the DCIS cases will advance to invasive ductal carcinoma (IDC); however, they are usually universally treated leading to overtreatment. While earlier premalignant breast lesions, such as atypical ductal hyperplasia, are nearly all luminal and positive for estrogen receptor α (ER+), up to 8% DCIS are basal-like, which is more aggressive. We have previously shown that N-Ras, which is highly expressed selectively in the basal-like subtype, can promote the growth and transforming activity of basal-like breast cancer (PMID 26166574). In this study we investigate whether NRAS expression at DCIS can promote basal-like properties and the progression to invasiveness.

Methods: NRAS mRNA levels in normal, DCIS, and IDC patient-derived microarray databases and tissue microarrays (TMAs) were compared using student t-test. Correlation between NRAS mRNA levels and basal-like properties was assessed by Pearson Correlation. ER protein levels were assessed by IHC. NRAS was expressed in a luminal DCIS cell line model SUM225PE cells and the resulting cells were injected intraductally into mice to assess expression of basal-like markers and invasiveness in vivo. Conversely, NRAS expression was silenced in a DCIS-like basal-like cell line SUM102 and increased expression of luminal markers was assessed by RNA-seq and western blot.

Results: In microarray databases, DCIS samples with higher NRAS mRNA levels are enriched with basal-like gene expression signature; furthermore, NRAS mRNA levels appear to increase progressively from normal to DICS and from DCIS to IDC. A similar correlation between high NRAS levels and invasiveness and high Ki67 levels in TMAs was observed by RNA FISH. High levels of NRAS mRNAs also correlated with low ER levels.

Conclusions: How to identify the subset of DCIS cases that will become invasive is critical for addressing the current problem of overtreatment. Our data support the hypothesis that high N-RAS levels in DCIS mark invasiveness, by presumably inducing basal-like more aggressive tumor activities. On-going studies will further delineate whether N-Ras is also responsible for driving DCIS to the invasive state.

Citation Format: Eric C Chang, Zeyi Zheng, Hanan Elsarraj, Yan Hong, Yichao Shen Shen, Flora Lo, Long Feng, Xian H.-F. Zhang, Fariba Behbod. N-RAS as a marker for DCIS progression [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-15.

Abstract PD8-08: Development of humanized immune DCIS models using patient peripheral blood derived hematopoietic stem cells (CD34+)

Background:

Ductal carcinoma in situ (DCIS) is the most common form of non-invasive breast cancer. To accurately study the natural progression of DCIS lesions in mice, we devised the mouse-intraductal (MIND) animal model, which involves intraductal injection of human DCIS epithelial cells into the mammary ducts of immunocompromised mice. To improve the translational application of the MIND model, we aimed to mimic the natural microenvironment of human DCIS with patient-derived immune cells and assess the role of engrafted immune cells on human DCIS progression. In order to achieve successful engraftment of the entire immune system in mice, we utilized MISTRG mice. These mice were developed by Rongvaux et al., on an immunodeficient (Rag2-/-IL2rγ-/-) background. The genes encoding human M-CSF (M), human IL-3 (I), SIRP1α (S), human thrombopoietin (TPO)(TR), and GM-CSF (G) were knocked into their respective mouse loci. As such, MISTRG mice are highly permissive for human hematopoiesis, supporting the development and function of lymphocytes, monocytes, and natural killer (NK) cells. In contrast, previous studies have used the humanized CD34+ NOD-SCID IL2rγ-/- mice (CD34+NSG), which are unable to support myeloid cell differentiation due to lack of expression of human-specific cytokines. Moreover, prior xenograft studies in the CD34+NSG mice have not used immune cells derived from the same patient as the tumor.

Results:

Human CD34+ cells derived from patients' peripheral blood were expanded ex vivo ˜100-fold using a novel formulation of culture medium. Transplantation of ex vivo expanded CD34+ cells via tail vein injection of MISTRG mice resulted in the successful engraftment of human immune cells as early as 4 weeks following injection. Successful engraftment was confirmed by flow cytometry using human specific antibodies that recognize human leukocytes (anti-CD45), T cells (anti-CD3), B cells (anti-CD20), and myeloid cells (anti-CD33) in spleen, bone marrow, and peripheral blood of MISTRG mice. Once engraftment was confirmed, DCIS epithelial cells from the same DCIS patients or DCIS cell lines were injected intraductally. Recruitment of patient-derived immune cells to the DCIS lesions was confirmed by immunofluorescence using human-specific antibodies that recognize neutrophils (anti-myeloperoxidase), macrophages (anti-CD68), M2-polarized macrophages (anti-c-MAF), natural killer cells (anti-CD56), dendritic cells (anti-CD21), T cells (anti-CD3) and B cells (anti-CD20).

Conclusion:

This model represents the first to enable the study of mechanisms of DCIS progression in a manner that fully represents the heterogeneity of human disease, including the influence of the patients' own immune cells on DCIS progression.

Citation Format: Behbod F, Harper H, Hansford H, Limback D, Hong Y, Elsarraj H, Ricci LR, Fan F, Tawfik O, May L, Cusick T, Inciardi M, Redick M, Gatewood J, Winblad O, Fields TA, Fabian C, Godwin AK, Fields PE, Meierotto R, Perry J. Development of humanized immune DCIS models using patient peripheral blood derived hematopoietic stem cells (CD34+) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD8-08.

Abstract P4-06-01: Patient derived DCIS mouse-intraductal (MIND) models recapitulate the full spectrum of human patient pathology and histologic features including progression to invasion in a subset of cases

Introduction: The 20-year breast cancer mortality rate following a DCIS diagnosis is ∼3%. Radiation and anti-hormonal therapy of DCIS has not resulted in improved overall survival, which argues against the non-selective use of such therapies in DCIS management. However, some DCIS cases do progress to invasive cancer, and these patients may benefit from treatment. A study of 80 DCIS patients followed for up to 30 years reported a 43% progression rate. Notably, progression was not predicted by grade, as 39% of even low-grade DCIS ultimately progressed to invasive cancer. Clearly, there is a need to identify which DCIS lesions are likely to progress. We have developed a novel mouse xenograft model (mouse-intraductal; MIND) to study the molecular basis of DCIS progression and enable identification of suitable biomarkers that predict invasive progression.

Methods: MIND involves injection of epithelial cells derived from patient breast lesions into the mammary ducts of immunocompromised mice. Serial sections of mouse mammary glands containing DCIS xenograft lesions were examined at time intervals of 3-14 months post-engraftment by histology using hematoxylin and eosin (H&E) and immunohistochemistry using anti-human cytokeratin 5/19, smooth muscle actin, ER, PR, p53, Ki67 and HER-2.

Results: Intraductal injection of cells derived from breast lesions of 28 patients into 133 mice resulted in a successful engraftment rate of 60%. Among these, 12 pure DCIS samples were injected into 35 different mice to create MIND xenografts. As early as three months post-engraftment, the DCIS xenograft cells showed multilayered in situ growth consisting of atypical neoplastic cells with prominent and vesicular nuclei. DCIS MIND xenografts exhibited the full spectrum of human DCIS histologic features, including similar biomarker expression (ER, PR, Ki67, HER-2 and p53) at long-term follow-up after engraftment (up to 12 months). Most remarkably, a subset of xenografts representing 5 patients (5/12; 42%) showed progression to invasion 6-12 months post-engraftment in the absence of any external genetic manipulations. This rate is very similar to that reported for human DCIS progression in untreated patients. MIND DCIS xenograft lesions that progressed showed disruption of basement membrane and myoepithelial layer by the invasive cells, retraction of basement membrane, and micro-invasion. MIND DCIS lesions were enriched in small capillaries, and in some cases clusters of invasive cells appeared inside nearby blood vessels.

Conclusion: The MIND xenograft is a viable model for human DCIS progression that recapitulates histologic features of human DCIS, as well as reported rates of progression to invasion. The availability of this innovative model provides a valuable tool for the discovery of new biomarkers to identify DCIS with invasive potential. The identification of high risk DCIS will ultimately help patients and clinicians choose the best course of therapy and avoid the morbidity and costs associated with unnecessary treatment.

Citation Format: Behbod F, Limback D, Hong Y, Elsarraj H, Berger J, Heddens E, Valdez K, Smith WP, Inciardi M, Reddick M, Gatewood J, Darrah J, Winblad O, Meierotto R, Ricci L, Wagner J, Amin A, May L, Cusick T, Mammen J, Fields T, Godwin AK, Fabian C, Kaufman C, Tawfik O, Fan F. Patient derived DCIS mouse-intraductal (MIND) models recapitulate the full spectrum of human patient pathology and histologic features including progression to invasion in a subset of cases [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-06-01.

Abstract P2-05-05: Expression profiling of in vivo DCIS progression models identified BCL9 as a molecular driver of invasive progression

Introduction: There are an estimated 60,000 new cases of ductal carcinoma in situ (DCIS) each year. At present, it is not clear why some DCIS remain non-invasive for decades while others become invasive. A lack of understanding in DCIS pathobiology has led to overtreatment of more than half of DCIS patients. To identify factors that promote DCIS invasion, we have profiled the temporal molecular changes during DCIS transition to invasive ductal carcinoma (IDC) using two in vivo models, MIND (mouse-intraductal) and DCIS/IDC tandem lesions. These studies led to the identification of B cell lymphoma-9 as a potential molecular driver of early invasion. BCL9 is a newly found co-activator of Wnt-stimulated β-catenin-mediated transcription. BCL9 has been shown to promote progression of multiple myeloma and colon carcinoma. However its role in breast cancer progression had not been recognized.

Methods: Microarray and RNA sequencing were utilized to characterize the sequential and temporal changes in mRNA expression during DCIS invasive transition. BCL9 shRNA knockdown was performed to assess the role of BCL9 in in vivo invasion, EMT and canonical Wnt signaling. Immunofluorescence of 28 patient DCIS samples was used to assess a correlation between the expression of BCL9 and biomarkers of high risk DCIS. TCGA data was analyzed to assess the status of BCL9 gene alterations in 959 human breast cancers.

Results: Analysis of BCL9, by RNA and protein showed BCL9 up-regulation to be associated with DCIS transition to IDC. Analysis of patient DCIS revealed a significant correlation between high nuclear BCL9 and pathologic characteristics associated with DCIS recurrence: ER and PR negative, high nuclear grade, and high HER2. In vivo silencing of BCL9 resulted in the inhibition of DCIS invasion and reversal of epithelial-mesenchymal transition (EMT). Analysis of the TCGA data showed BCL9 gene to be altered in 26% of breast cancers. This is a significant alteration when compared to ERBB2 (19%) and ESR1 (8%). A significantly higher proportion of basal like invasive breast cancers showed BCL9 amplification.

Conclusion: BCL9 is a molecular driver of DCIS invasive progression and may predispose to the development of basal like invasive breast cancers. As such, BCL9 has the potential to serve as a biomarker of high risk DCIS and as a therapeutic target for prevention of IDC.

Citation Format: Behbod F, Elsarraj H, Hong Y, Valdez K, Chien J, Godwin A, Fields T. Expression profiling of in vivo DCIS progression models identified BCL9 as a molecular driver of invasive progression. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-05-05.

Abstract B01: B cell lymphoma 9 mediates a cross talk between the canonical Wnt and EGFR signaling in breast cancer

Human ductal carcinoma in situ (DCIS) are the most common type of non-invasive breast cancers. The five-year survival rate for women diagnosed with non-invasive DCIS is 98% while the five-year survival plummets to 83-27% for breast cancers that have become invasive and have spread to distant sites [also referred to as invasive ductal carcinoma (IDC)]. To study DCIS pathobiology and factors that promote their transition to IDC, we have developed a novel in vivo DCIS model, MIND (mouse-intraductal), that involves intraductal injection of epithelial cells derived from primary human DCIS biopsy and surgical samples thus mimicking the entire process of DCIS to IDC transition. As a complementary approach, we have utilized human DCIS/IDC tandem lesions, which are patient DCIS that show a transition to IDC within the same breast. Analysis of RNA and protein at distinct stages of in situ to IDC using both models showed B cell lymphoma-9 (BCL9) up-regulation to be associated with DCIS transition to IDC. BCL9 is a recently identified co-activator of Wnt-stimulated beta-catenin-mediated transcription. Our studies showed that in vivo silencing of BCL9 led to inhibition of DCIS invasion and reversal of EMT. We have also demonstrated a direct binding interaction between BCL9 and beta-catenin and showed suppression of beta-catenin-mediated transcription by BCL9 knockdown. Analysis of patient DCIS samples revealed a significant correlation between high nuclear BCL9 expression and pathologic characteristics associated with DCIS recurrence: Estrogen receptor (ER) negative and Ki67. Furthermore, analysis of the TCGA data showed BCL9 gene to be upregulated in 26% of breast cancers. This is a significant gene alteration when compared to HER2 (ERBB2) gene (19%) and estrogen receptor (ESR1) gene (8%) alterations in breast cancers. Interestingly, a significantly higher proportion of basal like invasive breast cancers compared to luminal breast cancers showed BCL9 amplification suggesting that BCL9 may predispose to the development of basal breast cancers. We have performed an RPPA analysis on our DCIS cell lines KD BCL9 vs. control. This analysis indicated that BCL9 KD showed down-regulation in a number of genes in the EGFR signaling pathway including p-EGFR, p-HER2, p-STAT3, and p-Src. Conclusion: BCL9 is a molecular driver of DCIS invasive progression. The molecular mechanism for BCL9's role in breast cancer progression is through the enhancement in the canonical Wnt and EGFR signaling.

Citation Format: Hanan Elsarraj, Hong Yan, Jennifer Knapp, Anna Tsimelzon, Shixia Huang, Andrew Godwin, Sue Hilsenbeck, Dean Edwards, Fariba Behbod. B cell lymphoma 9 mediates a cross talk between the canonical Wnt and EGFR signaling in breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B01.

Mouse Mammary Intraductal (MIND) Method for Transplantation of Patient Derived Primary DCIS Cells and Cell Lines

The MIND method involves intraductal injection of patient derived ductal carcinoma in situ (DCIS) cells and DCIS cell lines (MCF10DCIS.COM and SUM225) inside the mouse mammary ducts [Video 1 and Figure 1 in Behbod et al. (2009)]. This method mimics the normal environment of DCIS and facilitates study of the natural progression of human DCIS, i.e., their initial growth as carcinoma in situ within the ducts, followed by invasion into the stroma through the myoepithelial cell layer and basement membrane (Behbod et al., 2009; Valdez et al., 2011). In order to demonstrate that transplantation procedure is successful, the transplanted mammary glands may be excised as early as two weeks following intraductal injection of cells followed by Hematoxylin and Eosin (H&E) staining and/or immunofluorescence staining using human specific cytokeratin 5 and/or 19 [please see Figures 2-4 in Behbod et al. (2009)]. Additionally, the presence of trypan blue inside the mouse mammary ducts immediately following intraductal injection is the best indicator that the injection was successful (Video 1 starting at 4:33 sec).