Radisky, Derek C.

Abstract An estimated 1.6 million breast biopsies are performed annually in the United States, and the vast majority are benign. Benign breast disease is an established breast cancer risk factor for both Caucasian and African American women. Yet little is still known about benign breast tissue from African American women, who suffer from disproportionately high-grade tumors and poorer breast cancer survival. To better characterize the risk of breast cancer among African American women with benign breast disease, we assessed benign breast disease pathology of African American women in our metropolitan Detroit cohort (n = 3,737). We classified benign breast lesions for pathological characteristics and used logistic regression to estimate subsequent breast cancer risk with histological characteristics. We observed that women whose biopsies showed columnar alterations, columnar cell lesions of the breast, were 1.78-fold more likely to develop an invasive breast cancer [odds ratio (OR) 1.78, 95% confidence interval (CI) 1.19-2.65] after adjusting for age at biopsy, biopsy year, and overall impression. Columnar alterations were not found to be significantly associated with risk of developing ductal carcinoma in situ (DCIS) among African American women [OR 1.53, 95% CI 0.83-2.82]. Next, to identify molecular markers associated with columnar alterations in benign breast lesions, we performed gene expression analyses on biopsy tissues from 27 African American women that subsequently developed an invasive breast cancer. Transcriptional profiling of these lesions identified differentially expressed genes significantly associated with columnar alterations, including ankyrin repeat domain 30A (ANKRD30A). ANKRD30A, also known as NY-BR-1, is a mammary tissue-specific differentiation antigen that is overexpressed in breast cancers. Increased expression of ANKRD30A in benign breast lesions with columnar alterations may be indicative of subsequent breast cancer development. Taken together, novel molecular markers, including ANKRD30A, and ethnicity can lead to better risk assessment and earlier diagnosis of breast cancer. Citation Format: Andreana N. Holowatyj, Rouba Ali-Fehmi, Julie J. Ruterbusch, Eman Abdulfatah, Vishakha Pardeshi, Woodlyne Roquiz, Baraa Alosh, Sudeshna Bandyopadhyay, Derek Radisky, Michele L. Cote. Ankyrin repeat domain 30A as a novel molecular marker of columnar alterations in benign breast disease and subsequent breast cancer in African American women. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-378.

Abstract Background: Age-related lobular involution (LI) is a physiological process in which the terminal duct lobular units of the breast regress as a woman ages. Analyses of breast biopsies from women with benign breast disease (BBD) have found that extent of LI is negatively associated with subsequent breast cancer development. Here we assess the natural course of LI within individual women, and the impact of progressive LI on breast cancer risk. Methods: The Mayo Clinic BBD cohort consists of 13,455 women with BBD from 1967-2001. The BBD cohort includes 1115 women who had multiple benign biopsies, 106 of whom had developed breast cancer. Within this multiple biopsy cohort, the progression of the LI process was examined by age at initial biopsy and time between biopsies. The relationship between LI progression and breast cancer risk was assessed using standardized incidence ratios (SIRs) and by Cox proportional hazards analysis. Results: Women who had multiple biopsies were younger age and had a slightly higher family history of breast cancer as compared with the overall BBD cohort. Extent of LI at subsequent biopsy was greater with increasing time between biopsies and for women age 55+ at initial biopsy. Among women with multiple biopsies, there was a significant association of higher breast cancer risk among those with involution stasis (lack of progression, HR 1.63) as compared with those with involution progression, p = 0.036. Conclusions: The multiple biopsy BBD cohort allows for a longitudinal study of the natural progression of LI. The majority of women in the multiple biopsy cohort showed progression of LI status between benign biopsies, and extent of progression was highest for women who were in the perimenopausal age range at initial biopsy. Progression of LI status between initial and subsequent biopsy was associated with decreased breast cancer risk. Citation Format: Derek Radisky, Daniel W. Visscher, Ryan Frank, Robert A. Vierkant, Stacey J. Winham, Melody L. Stallings-Mann, Tanya L. Hoskin, Aziza Nassar, Celine M. Vachon, Lori A. Denison, Lynn C. Hartmann, Marlene H. Frost, Amy C. Degnim. Natural history of age-related lobular involution and impact on breast cancer risk. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-364.

Abstract This study investigates how increased stiffness of the tumor microenvironment (TME) can facilitate cellular multinucleation. Multinucleation is an easily observable marker for polyploidy, facilitating the quantification of this phenotype. Polyploidy is commonly an intermediate to aneuploidy, defined as an abnormal number of chromosomes, a phenotype found in 85% of solid cancers that can drive tumorigenesis. Up to 37% percent of tumors exhibit whole-genome doubling, which typically precedes other somatic copy number alterations. Additionally, induction of tetraploidy in human cells promoted increased tolerance for mutation, resistance to chemotherapeutic drugs, and transformation in culture. Tumors are inherently stiffer than normal tissue, and this property has been shown to affect cell growth and proliferation. Similarly, cell cycle errors have long been linked to chromosomal abnormalities. Here, we used engineered two-dimensional substrata that mimic tumor and normal microenvironments to investigate how matrix stiffness regulates multinucleation in mammary epithelial cells. Cells cultured on “stiff” substrata, representing tumor tissue, showed a nearly 14-fold increase in multinucleation compared to cells cultured on “soft” substrata, representing normal tissue. We found that multinucleation was regulated in part by signaling downstream of MMP3, a protease commonly upregulated in cancer. This signaling depended on expression of the Rac1 splice variant, Rac1b, production of reactive oxygen species (ROS), and expression of Snail. Under all conditions, cells cultured on soft substrata maintained a low frequency of multinucleation. We also investigated biochemical effectors downstream of Snail. Aurora A kinase (Aurora A) is a mitotic regulator commonly elevated in cancer that has been shown to induce multinucleation in mammary epithelial cells and increase tumor incidence in mice. We found using microarray analysis that MMP3 increases the levels of Aurora A in mammary epithelial cells. We further discovered that upregulation of Aurora A in response to MMP3 signaling was limited to one transcript variant. These data suggest that an increase in multinucleation is driven by the stiffening of the tissue during tumorigenesis, in part by MMP3-induced signaling and regulation of Aurora A splicing. More broadly, these data suggest a key role for the mechanical properties of the tumor microenvironment in cancer progression. Citation Format: Allison K. Simi, Derek C. Radisky, Celeste M. Nelson. Tissue stiffness regulates multinucleation in mammary epithelial cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5097.

Abstract The mechanical and chemical properties of the cellular microenvironment can influence the phenotype of cancer cells. The hypoxic conditions within solid breast tumors can contribute to invasiveness and the formation of breast cancer stem cells (CSCs). Integrin-linked kinase (ILK) is a critical mediator for mechanotransduction, a process that converts exogenous mechanical stimuli into biochemical signals. Yet, it is unclear how the physical properties of the tumor microenvironment, including matrix stiffness and hypoxia, integrate to direct the formation of the breast CSC niche. Using an innovative engineered culture model, we found that stiff and hypoxic microenvironments activate integrin signaling and a stem-like gene signature in breast cancer cells, suggesting that integrin signaling, matrix mechanics and oxygen tension cooperatively promote the formation of breast CSCs. Stiff and hypoxic microenvironments promote integrin signaling and the expression of CSC markers including CD44 and Nanog. Knocking down ILK reverts the CSC phenotype of invasive breast cancer cells on stiff matrix, and abrogates their ability to form mammospheres and colonies in soft agar. In contrast, ectopic expression of ILK enhances CSC properties. ILK promotes integrin signaling and the CSC phenotype through the PI3K/Akt pathway. Stiff microenvironments promote tumor formation and metastasis in ovo. ILK depletion significantly abrogates the tumorigenenic and metastatic potential of invasive breast cancer cells in ovo. Importantly, we found that breast cancer cells expressing ILK and the CSC marker CD44 were only present in the regions of tumors predicted to be stiff in breast cancer patient samples. Our data suggest that ILK act as an essential mechanosensor that regulates breast CSC phenotype in response to matrix mechanics and oxygen tension to regulate the formation of breast CSCs. Citation Format: Mei-Fong Pang, Melody Stallings-Mann, Michael J. Siedlik, Victor D. Varner, Siyang Han, Derek C. Radisky, Celeste M. Nelson. Tissue stiffness and hypoxia regulate breast cancer stem cells through ILK. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4395.

BACKGROUNDWomen with atypical hyperplasia (AH) on breast biopsy have a substantially increased risk of breast cancer (BC). Here the BC risk for the extent and subtype of AH is reported for 2 separate cohorts.METHODSAll samples containing AH were included from 2 cohorts of women with benign breast disease (Mayo Clinic and Nashville). Histology review quantified the number of foci of atypical ductal hyperplasia (ADH) and atypical lobular hyperplasia (ALH). The BC risk was stratified for the number of AH foci within AH subtypes.RESULTSThe study included 708 Mayo AH subjects and 466 Nashville AH subjects. In the Mayo cohort, an increasing number of foci of AH was associated with a significant increase in the risk of BC both for ADH (relative risks of 2.61, 5.21, and 6.36 for 1, 2, and ≥3 foci, respectively; P for linear trend = .006) and for ALH (relative risks of 2.56, 3.50, and 6.79 for 1, 2, and ≥3 foci, respectively; P for linear trend = .001). In the Nashville cohort, the relative risks of BC for ADH were 2.70, 5.17, and 15.06 for 1, 2, and ≥3 foci, respectively (P for linear trend < .001); for ALH, the relative risks also increased but not significantly (2.61, 3.48, and 4.02, respectively; P = .148). When the Mayo and Nashville samples were combined, the risk increased significantly for 1, 2, and ≥3 foci: the relative risks were 2.65, 5.19, and 8.94, respectively, for ADH (P < .001) and 2.58, 3.49, and 4.97, respectively, for ALH (P = .001).CONCLUSIONSIn 2 independent cohort studies of benign breast disease, the extent of atypia stratified the long‐term BC risk for ADH and ALH. Cancer 2016;122:2971‐2978. © 2016 American Cancer Society.

Abstract Basal subtype breast cancers have a particularly poor prognosis, with high invasiveness and resistance to most targeted therapies. TGFβ and MYC drive central features of basal breast cancer: TGFβ is an autocrine and paracrine signaling factor that drives cell invasion and metastasis, and MYC is a central regulator of cellular proliferation that is upregulated in many cancer types. We show here that genetic or pharmacologic inhibition of MYC in MCF10A basal breast cells results in increased sensitivity to TGFβ-stimulated invasion and metastasis and also show that this signaling loop is dependent on activation of SRC. Analysis of human breast cancer datasets and additional experiments with breast cancer cell lines further suggest the relevance of this signaling loop in basal, but not luminal, breast cancers. Our results imply precaution should be taken when utilizing therapeutic inhibitors of MYC with basal breast cancer patients as this could lead to increased metastasis; however, simultaneous pharmacologic inhibition of SRC and MYC for these patients could facilitate the antiproliferative effects of MYC inhibition while blocking the consequent promotion of metastasis. Cancer Res; 76(12); 3520–30. ©2016 AACR.

Engineered protein therapeutics offer advantages, including strong target affinity, selectivity and low toxicity, but like natural proteins can be susceptible to proteolytic degradation, thereby limiting their effectiveness. A compelling therapeutic target is mesotrypsin, a protease up-regulated with tumour progression, associated with poor prognosis, and implicated in tumour growth and progression of many cancers. However, with its unique capability for cleavage and inactivation of proteinaceous inhibitors, mesotrypsin presents a formidable challenge to the development of biological inhibitors. We used a powerful yeast display platform for directed evolution, employing a novel multi-modal library screening strategy, to engineer the human amyloid precursor protein Kunitz protease inhibitor domain (APPI) simultaneously for increased proteolytic stability, stronger binding affinity and improved selectivity for mesotrypsin inhibition. We identified a triple mutant APPIM17G/I18F/F34V, with a mesotrypsin inhibition constant (Ki) of 89 pM, as the strongest mesotrypsin inhibitor yet reported; this variant displays 1459-fold improved affinity, up to 350 000-fold greater specificity and 83-fold improved proteolytic stability compared with wild-type APPI. We demonstrated that APPIM17G/I18F/F34V acts as a functional inhibitor in cell-based models of mesotrypsin-dependent prostate cancer cellular invasiveness. Additionally, by solving the crystal structure of the APPIM17G/I18F/F34V–mesotrypsin complex, we obtained new insights into the structural and mechanistic basis for improved binding and proteolytic resistance. Our study identifies a promising mesotrypsin inhibitor as a starting point for development of anticancer protein therapeutics and establishes proof-of-principle for a novel library screening approach that will be widely applicable for simultaneously evolving proteolytic stability in tandem with desired functionality for diverse protein scaffolds.

Summary The transcription factor forkhead box protein A1 (FOXA1) plays a critical role in the proliferation of human breast cancer cells, particularly estrogen receptor alpha (ERα)‐positive luminal breast cancer cells. However, genetic studies of the requirement for Foxa1 in mammary tumor formation in mice have been hampered by the lack of a conditional gene ablation. We examined three mouse models of mammary‐specific ablation of Foxa1 in ductal epithelial cells to identify the best system for complete and mammary‐specific ablation of Foxa1. We found that MMTV‐Cre and MMTV‐rtTA;Tet‐On‐Cre led to partial deletion of Foxa1 and attenuated mammary duct formation, whereas Krt14‐Cre led to complete ablation of Foxa1 and abolished mammary duct formation, in Foxa1 loxP/loxP mice. These results demonstrate that Foxa1 is essential for mammary duct formation, and reveal a series of mouse models in which mammary expression of Foxa1 can be attenuated or completely blocked. Our study also suggests a potentially powerful model for complete ablation of Foxa1 in mammary epithelial cells using Krt14‐driven Cre expression in an inducible manner, such as Krt14‐rtTA;Tet‐On‐Cre . This model system will facilitate further in vivo functional studies of Foxa1 or other factors in mammary gland development and tumor formation and progression. genesis 54:277–285, 2016. © 2016 Wiley Periodicals, Inc.