Citations

Abstract Patients diagnosed with ovarian cancer face an average 5 year survival rate of 46%; low survival is driven by early and ongoing intraperitoneal dissemination and metastasis of the tumor. Among the different histotypes of ovarian cancer, ovarian clear cell carcinoma (OCCC) has a particularly poor prognosis when diagnosed in late stage, as these tumors tend to be chemoresistant, leaving no effective therapeutic options. Intraperitoneal metastasis requires cells to become anoikis resistant, where apoptosis normally induced by loss of attachment is suppressed. We seek to better understand the mechanisms involved in anoikis resistance in OCCC, which in the future could lead to new therapeutic strategies for these patients. We have found that Serine Protease Inhibitor Kazal type 1 (SPINK1), an endogenous inhibitor of trypsin like serine proteases, is also an important regulator of anoikis resistance in some ovarian cancers. In this study, we aimed to dissect the role of SPINK1 specifically in OCCC, defining its contribution to anoikis resistance using cultured OCCC cell lines and elucidating its mechanism of action. We compared anoikis resistance of cells with endogenous SPINK1 expression versus cells in which SPINK1 was silenced using lentiviral shRNA constructs, when culturing cells on ultra-low attachment plates to mimic cell detachment from the extracellular matrix. We found that knockdown of SPINK1 reduced survival and stimulated apoptotic pathways in OCCC cells grown under detached conditions, implicating SPINK1 in anoikis resistance of OCCC cells. As a secreted protease inhibitor, SPINK1 may be expected to confer anoikis resistance by inhibiting an extracellular serine protease involved in triggering anoikis. Because many proteases represent potential targets of SPINK1, we have designed a strategy using Activity Based Protein Profiling (ABPP) to discover the targets of SPINK1 from among this large pool of candidates. In pilot studies, we have successfully used a novel activity-based probe to covalently label the active sites of serine proteases secreted from OCCC cells. In ongoing efforts, we are optimizing methods to identify labeled proteases with high sensitivity using tandem mass spectrometry. We will then identify those proteases regulated by SPINK1 through comparison of labeled proteomes from OCCC cells with and without SPINK1 treatment,, and candidate proteases will be further analyzed for their role in triggering anoikis. The identification of SPINK1 regulated proteases that are responsible for mediating anoikis in our models will give insight into important mechanisms whereby tumor cells acquire resistance to anoikis in OCCC. In-depth understanding of anoikis resistance, a critical component of ovarian cancer progression and metastasis, may lead to novel biomarkers of disease progression as well as important therapeutic targets. Citation Format: Christine Mehner, Mathew A. Coban, Alexandra Hockla, Derek C. Radisky, Evette S. Radisky. Serine protease inhibitor Kazal type 1 (SPINK1) drives anoikis resistance in ovarian clear cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 442.

ABSTRACT Dimethylarginine dimethylaminohydrolases (DDAHs) are known to degrade asymmetric dimethylarginine, an endogenous inhibitor of NOS, and maintain vascular homeostasis; however, the regulatory pathways of DDAHs remain unclear. In this study, we aimed to define the role of transmembrane glycoprotein neuropilin‐1 (NRP1) in the expression of DDAHs and investigate the potential roles of NRP1 in regulation of blood pressure. Short hairpin RNA–mediated knockdown of NRP1 reduced the level and mRNA stability of DDAH1 but not DDAH2 in HUVECs, whereas overexpression of NRP1 increased the mRNA stability of DDAH1. Meanwhile, mesenteric arteries and lung vascular endothelial cells of tamoxifen‐inducible endothelial cell–specific NRP1 knockout mice exhibited decreased expression of DDAH1 and slightly increased expression of DDAH2. Mechanistically, the regulation of NRP1 on DDAH1 expression is mediated by a posttranscriptional mechanism involving miR‐219‐5p in HUVECs. Although the endothelial cell–specific NRP1 knockout mice did not exhibit any significant change in blood pressure at the basal level, they were more sensitive to low‐dose angiotensin II infusion–induced increases in blood pressure. Our results show that NRP1 is required for full expression of DDAH1 in endothelial cells and that NRP1 contributes to protection from low‐dose angiotensin II–induced increases in blood pressure.—Wang, Y., Wang, E., Zhang, Y., Madamsetty, V. S., Ji, B., Radisky, D. C., Grande, J. P., Misra, S., Mukhopadhyay, D. Neuropilin‐1 maintains dimethylarginine dimethylaminohydrolase 1 expression in endothelial cells, and contributes to protection from angiotensin II–induced hypertension. FASEB J. 33, 494–500 (2019). www.fasebj.org

Background More than 1.5 million women per year have a benign breast biopsy resulting in concern about their future breast cancer (BC) risk. This study examined the performance of 2 BC risk models that integrate clinical and histologic findings in this population. Methods The BC risk at 5 and 10 years was estimated with the Breast Cancer Surveillance Consortium (BCSC) and Benign Breast Disease to Breast Cancer (BBD‐BC) models for women diagnosed with benign breast disease (BBD) at the Mayo Clinic from 1997 to 2001. Women with BBD were eligible for the BBD‐BC model, but the BCSC model also required a screening mammogram. Calibration and discrimination were assessed. Results Fifty‐six cases of BC were diagnosed among the 2142 women with BBD (median age, 50 years) within 5 years (118 were diagnosed within 10 years). The BBD‐BC model had slightly better calibration at 5 years (0.89; 95% confidence interval [CI], 0.71‐1.21) versus 10 years (0.81; 95% CI, 0.70‐1.00) but similar discrimination in the 2 time periods: 0.68 (95% CI, 0.60‐0.75) and 0.66 (95% CI, 0.60‐0.71), respectively. In contrast, among the 1089 women with screening mammograms (98 cases of BC within 10 years), the BCSC model had better calibration (0.94; 95% CI, 0.85‐1.43) and discrimination (0.63; 95% CI, 0.56‐0.71) at 10 years versus 5 years (calibration, 1.31; 95% CI, 0.94‐2.25; discrimination, 0.59; 95% CI, 0.46‐0.71) where discrimination was not different from chance. Conclusions The BCSC and BBD‐BC models were validated in the Mayo BBD cohort, although their performance differed by 5‐year risk versus 10‐year risk. Further enhancement of these models is needed to provide accurate BC risk estimates for women with BBD.

Purpose Women with atypical hyperplasia (AH) on breast biopsy have an aggregate increased risk of breast cancer (BC), but existing risk prediction models do not provide accurate individualized estimates of risk in this subset of high-risk women. Here, we used the Mayo benign breast disease cohort to develop and validate a model of BC risk prediction that is specifically for women with AH, which we have designated as AH-BC. Patients and Methods Retrospective cohorts of women age 18 to 85 years with pathologically confirmed benign AH from Rochester, MN, and Nashville, TN, were used for model development and external validation, respectively. Clinical risk factors and histologic features of the tissue biopsy were selected using L1-penalized Cox proportional hazards regression. Identified features were included in a Fine and Gray regression model to estimate BC risk, with death as a competing risk. Model discrimination and calibration were assessed in the model-building set and an external validation set. Results The model-building set consisted of 699 women with AH, 142 of whom developed BC (median follow-up, 8.1 years), and the external validation set consisted of 461 women with 114 later BC events (median follow-up, 11.4 years). The final AH-BC model included three covariates: age at biopsy, age at biopsy squared, and number of foci of AH. At 10 years, the AH-BC model demonstrated good discrimination (0.63 [95% CI, 0.57 to 0.70]) and calibration (0.87 [95% CI, 0.66 to 1.24]). In the external validation set, the model showed acceptable discrimination (0.59 [95% CI, 0.51 to 0.67]) and calibration (0.91 [95% CI, 0.65 to 1.42]). Conclusion We have created a new model with which to refine BC risk prediction for women with AH. The AH-BC model demonstrates good discrimination and calibration, and it validates in an external data set.

High structural and sequence similarity within protein families can pose significant challenges to the development of selective inhibitors, especially toward proteolytic enzymes. Such enzymes usually belong to large families of closely similar proteases and may also hydrolyze, with different rates, protein- or peptide-based inhibitors. To address this challenge, we employed a combinatorial yeast surface display library approach complemented with a novel pre-equilibrium, competitive screening strategy for facile assessment of the effects of multiple mutations on inhibitor association rates and binding specificity. As a proof of principle for this combined approach, we utilized this strategy to alter inhibitor/protease association rates and to tailor the selectivity of the amyloid β-protein precursor Kunitz protease inhibitor domain (APPI) for inhibition of the oncogenic protease mesotrypsin, in the presence of three competing serine proteases, anionic trypsin, cationic trypsin and kallikrein-6. We generated a variant, designated APPIP13W/M17G/I18F/F34V, with up to 30-fold greater specificity relative to the parental APPIM17G/I18F/F34V protein, and 6500- to 230 000-fold improved specificity relative to the wild-type APPI protein in the presence of the other proteases tested. A series of molecular docking simulations suggested a mechanism of interaction that supported the biochemical results. These simulations predicted that the selectivity and specificity are affected by the interaction of the mutated APPI residues with nonconserved enzyme residues located in or near the binding site. Our strategy will facilitate a better understanding of the binding landscape of multispecific proteins and will pave the way for design of new drugs and diagnostic tools targeting proteases and other proteins.

Abstract Multinucleation is found in more than one third of tumors and is linked to increased tolerance for mutation, resistance to chemotherapy, and invasive potential. The integrity of the genome depends on proper execution of the cell cycle, which can be altered through mechanotransduction pathways as the tumor microenvironment stiffens during tumorigenesis. Here, we show that signaling downstream of matrix metalloproteinase-3 (MMP3) or TGFβ, known inducers of epithelial–mesenchymal transition (EMT), also promotes multinucleation in stiff microenvironments through Snail-dependent expression of the filament-forming protein septin-6, resulting in midbody persistence, abscission failure, and multinucleation. Consistently, we observed elevated expression of Snail and septin-6 as well as multinucleation in a human patient sample of metaplastic carcinoma of the breast, a rare classification characterized by deposition of collagen fibers and active EMT. In contrast, a soft microenvironment protected mammary epithelial cells from becoming multinucleated by preventing Snail-induced upregulation of septin-6. Our data suggest that tissue stiffening during tumorigenesis synergizes with oncogenic signaling to promote genomic abnormalities that drive cancer progression. Significance: These findings reveal tissue stiffening during tumorigenesis synergizes with oncogenic signaling to promote genomic abnormalities that drive cancer progression. Cancer Res; 78(9); 2277–89. ©2018 AACR.

MMP ‐14 and MMP ‐9 are two well‐established cancer targets for which no specific clinically relevant inhibitor is available. Using a powerful combination of computational design and yeast surface display technology, we engineered such an inhibitor starting from a nonspecific MMP inhibitor, N‐ TIMP 2. The engineered purified N‐ TIMP 2 variants showed enhanced specificity toward MMP ‐14 and MMP ‐9 relative to a panel of off‐target MMP s. MMP ‐specific N‐ TIMP 2 sequence signatures were obtained that could be understood from the structural perspective of MMP /N‐ TIMP 2 interactions. Our MMP ‐9 inhibitor exhibited 1000‐fold preference for MMP ‐9 vs. MMP ‐14, which is likely to translate into significant differences under physiological conditions. Our results provide new insights regarding evolution of promiscuous proteins and optimization strategies for design of inhibitors with single‐target specificities.

Mechanical forces are increasingly recognized to regulate morphogenesis, but how this is accomplished in the context of the multiple tissue types present within a developing organ remains unclear. Here we use bioengineered “microfluidic chest cavities” to precisely control the mechanical environment of the fetal lung. We show that transmural pressure controls airway branching morphogenesis, the frequency of airway smooth muscle contraction, and the rate of developmental maturation of the lungs, as assessed by transcriptional analyses. Timelapse imaging reveals that branching events are synchronized across distant locations within the lung, and are preceded by long-duration waves of airway smooth muscle contraction. Higher transmural pressure decreases the interval between systemic smooth muscle contractions and increases the rate of morphogenesis of the airway epithelium. These data reveal that the mechanical properties of the microenvironment instruct crosstalk between different tissues to control the development of the embryonic lung.

Abstract In breast adipose tissue, macrophages that encircle damaged adipocytes form “crown-like structures of breast” (CLS-B). Although CLS-B have been associated with breast cancer, their role in benign breast disease (BBD) and early carcinogenesis is not understood. We evaluated breast biopsies from three age-matched groups (n = 86 each, mean age 55 years), including normal tissue donors of the Susan G. Komen for the Cure Tissue Bank (KTB), and subjects in the Mayo Clinic Benign Breast Disease Cohort who developed cancer (BBD cases) or did not develop cancer (BBD controls, median follow-up 14 years). Biopsies were classified into histologic categories, and CD68-immunostained tissue sections were evaluated for the frequency and density of CLS-B. Our data demonstrate that CLS-B are associated with BBD: CLS-B–positive samples were significantly less frequent among KTB biopsies (3/86, 3.5%) than BBD controls (16/86 = 18.6%, P = 0.01) and BBD cases (21/86 = 24%, P = 0.002). CLS-B were strongly associated with body mass index (BMI); BMI < 25: 7% CLS-B positive, BMI 25–29: 13%, and BMI ≥ 30: 29% (P = 0.0005). Among BBD biopsies, a high CLS-B count [>5 CLS-B/sample: 10.5% (BBD cases) vs 4.7% (BBD controls), P = 0.007] conferred a breast cancer OR of 6.8 (95% CI, 1.4–32.4), P = 0.02, after adjusting for adipose tissue area (cm2), histologic impression, and BMI. As high CLS-B densities are independently associated with an increased breast cancer risk, they may be a promising histologic marker of breast cancer risk in BBD. Cancer Prev Res; 11(2); 113–9. ©2017 AACR.