Abstract 2356: Aberrant TIMP-1 secretion by tumor-associated fibroblasts is a major contributor to the selective positive response to nintedanib in lung adenocarcinoma

Adenocarcinoma (ADC) and Squamous Cell Carcinoma (SCC) are the most frequent histologic subtypes of lung cancer, and both are rich in activated/myofibroblast-like tumor-associated fibroblasts (TAFs). Nintedanib is a potent antifibrotic drug that targets the tumor stroma and is clinically approved to treat advanced lung ADC patients owing to the survival benefits observed in the LUME-1 clinical trial in ADC but not SCC patients. Although the mechanism underlying the ADC-selective therapeutic effects of nintedanib remained poorly understood, we have previously reported that nintedanib abrogates the pro-tumoral traits of the secretome of ADC-TAFs but not SCC-TAFs, suggesting that secreted factor(s) in ADC-TAFs may be implicated. In addition, we recently unveiled an ADC-specific tumor-promoting crosstalk between TAFs and cancer cells driven by TIMP-1 and CD63, whereas others have shown that TIMP-1 is a molecular target of nintedanib. However, it remains unknown if TIMP-1 is involved in the ADC-selective benefits of nintedanib. To address this question, we used patient-derived TAFs obtained with the patient’s informed consent and using protocols approved by the Ethics Committee of the Hospital Clinic. We treated TGF-β1-activated ADC-TAFs and SCC-TAFs with nintedanib and determined the content of TIMP-1 in their conditioned medium by ELISA. Moreover, we used cell-based functional assays and tumor xenografts after knocking-down TIMP-1 in TAFs by siRNA to examine how silencing TIMP-1 altered their response to nintedanib. By analyzing TCGA data and the human protein atlas, we found that TIMP-1 is consistently upregulated in ADC compared to SCC tumors both at the mRNA and protein levels. Moreover, TCGA data revealed that TIMP-1 is increased in tumors compared to paired control tissue in ADC but not SCC. In culture, we observed that TIMP-1 secretion was higher in ADC-TAFs than SCC-TAFs, and that this secretion was downregulated by nintedanib to a larger extent in ADC-TAFs compared to SCC-TAFs. In vivo analyses revealed that ADC cells co-injected with fibroblasts silenced for TIMP-1 as in SCC-TAFs into immunocompromised mice exhibited a less invasive growth pattern compared to tumors bearing control fibroblasts. In addition, we observed that the inhibition of the pro-tumoral secretome of ADC-TAFs elicited by nintedanib was abrogated upon knocking-down TIMP-1 in TAFs both in vitro and in vivo. Collectively, these results reveal that the high secretion of TIMP-1 in ADC-TAFs render them more responsive to nintedanib, whereas the low TIMP-1 secretion of SCC-TAFs may be a major contributor to the selective resistance of SCC patients to nintedanib. Moreover, our results identify TIMP-1 as a promising predictive biomarker of nintedanib responses.

Citation Format: Paula Duch, Natalia Díaz-Valdivia, Marta Gabasa, Rafael Ikemori, Frank Hilberg, Noemí Reguart, Derek Radisky, Jordi Alcaraz. Aberrant TIMP-1 secretion by tumor-associated fibroblasts is a major contributor to the selective positive response to nintedanib in lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2356.

Abstract P2-11-14: Pathology AI features and immune biomarkers of postpartum involution: Implications for postpartum breast cancer

Breast cancer risk is increased in parous women in the period following childbirth, peaking at five years. After weaning or in the absence of lactation, the breast undergoes postpartum involution (PPI), a process characterized by epithelial cell death and tissue remodeling that returns the mammary gland to a baseline state, and has previously been associated with increased inflammation and breast cancer development and progression in preclinical models. Features of PPI and determinants of related inflammation have been incompletely characterized among women. In this study, we performed visual and AI analysis of 725 digitized H&E images of normal breast tissues donated to the Komen Tissue Bank (KTB) by parous and nulliparous women ≤45 years, and further investigated the immune microenvironment in specimens from 23 women (also from KTB, 13 parous, 10 nulliparous) using NanoString RNA immuno oncology (IO) 360 panels and immune protein biomarkers by NanoString GeoMx Digital Spatial Profiling (DSP). We found that recently parous women (≤5 years of a last birth) had higher numbers of terminal duct lobular units (TDLUs), immune cells, and plasma cells as compared with nulliparous women, and that beyond 5 years of a last birth, TDLU numbers were still higher in parous women, but the immune and plasma cell content of the breast of parous and nulliparous women were not significantly different. Our gene expression analysis revealed differential expression of genes that clustered according to parity status, with interferon stimulated genes; STAT1 and IFITM1, and interferon alpha receptor 1 (IFNAR1), and MHC class II genes (HLA-DMA, HLA-DPA,HLA-DPB1, and HLA-DRA) elevated in parous women. Our DSP analysis revealed that immune biomarkers with immunosuppressive functions, including ARG1, VISTA, CTLA-4, and CD68 were significantly higher in parous women as compared with nulliparous women. Breast tissues of parous women show lobular expansion and alterations in immune cell components compared with nulliparous tissues. Further research is needed to assess how these alterations may impact risk.

Citation Format: Joshua Were Ogony, Thomas De Bel, Derek Radisky, Jeroen VanderLaak, Mark Sherman. Pathology AI features and immune biomarkers of postpartum involution: Implications for postpartum breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-11-14.

Abstract 3167: Stromal TIMP-1 drives tumor progression in lung adenocarcinoma through CD63 interaction

The two most common lung cancer subtypes are adenocarcinoma (ADC) and squamous cell carcinoma (SCC). Even though both subtypes are epithelial in origin, it is now clear that tumor associated fibroblasts (TAFs) are key regulators of tumor progression and response to therapies. Nintedanib is an antifibrotic drug that targets the tumor stroma and has been clinically approved to treat lung ADC patients owing to the therapeutic benefits exhibited by this drug selectively in ADC (but not in SCC) in the LUME-1 cinical trial. We have implicated recently both ADC-TAFs and ADC cancer cells in the selective effects of nintedanib in ADC, since this drug reduced the growth and invasion induction elicited by the secretome of TGF-β-activated ADC-TAFs on a panel of ADC cells, whereas such reduction was not observed in SCC-TAFs. However, the key molecules involved in the aberrant TAF-carcinoma crosstalk in ADC remain unknown. TIMP-1 is a multifunctional protein that has been associated with poor prognosis in lung cancer and is downregulated by nintedanib in a bleomycin model of pulmonary fibrosis. Our preliminary results revealed that the TIMP-1 receptor CD63 is overexpressed in ADC patients compared to SCC. Therefore, our working hypothesis was that nintedanib reduces ADC cells growth and invasion by abrogating the TAF-carcinoma crosstalk driven by TIMP-1 and CD63.To test this hypothesis, we used primary TAFs obtained with the patient informed consent, and using protocols approved by the Ethics Committee of the Hospital Clinic. TGF-β1-activated ADC-TAFs and SCC-TAFs were treated with nintedanib, and their secreted TIMP-1 was determined by ELISA. Two high-CD63 cell lines (H1437 and H23) were used in some experiments, and siRNA was used to knock-down either TIMP-1 in TAFs or CD63 in cancer cellsOur in vitro results showed that the secretion of TIMP-1 was significantly larger in ADC-TAFs compared to SCC-TAFs. Likewise, nintedanib elicited a higher TIMP-1 downregulation in ADC-TAFs compared SCC-TAFs. Of note, TIMP-1 and CD63 were both implicated in the pro-tumorigenic crosstalk, since knocking-down TIMP-1 in ADC-TAFs or CD63 in ADC cells was sufficient to abrogate the growth and invasion enhancement elicited by the secretome of TAFs. Moreover, CD63 was necessary to enhance the invasion of ADC cells upon stimulation with recombinant TIMP-1. In addition, we found that knocking-down TIMP-1 in ADC-TAFs was sufficient to compromise the inhibitory effects of nintedanib on the growth and invasion enhancement elicited by the secretome of TAFs on ADC cells. Collectively, our results support a novel TAF-carcinoma crosstalk driven by TIMP-1 and CD63 in lung ADC, and support that such heterotypic crosstalk may underlie the aberrant tumor-promoting effects of ADC-TAFs that are selectively downregulated by nintedanib.

Citation Format: Paula Duch, Natalia Díaz-Valdivia, Marta Gabasa, Rafael Ikemori, Marselina Arshakyan, Frank Hillberg, Noemí Reguart, Derek Radisky, Jordi Alcaraz. Stromal TIMP-1 drives tumor progression in lung adenocarcinoma through CD63 interaction [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3167.

Aurora-A kinase oncogenic signaling mediates TGF-β-induced triple-negative breast cancer plasticity and chemoresistance

Triple-negative breast cancer (TNBCs) account for 15–20% of all breast cancers and represent the most aggressive subtype of this malignancy. Early tumor relapse and progression are linked to the enrichment of a sub-fraction of cancer cells, termed breast tumor-initiating cells (BTICs), that undergo epithelial to mesenchymal transition (EMT) and typically exhibit a basal-like CD44^high/CD24^low and/or ALDH1^high phenotype with critical cancer stem-like features such as high self-renewal capacity and intrinsic (de novo) resistance to standard of care chemotherapy. One of the major mechanisms responsible for the intrinsic drug resistance of BTICs is their high ALDH1 activity leading to inhibition of chemotherapy-induced apoptosis. In this study, we demonstrated that aurora-A kinase (AURKA) is required to mediate TGF-β-induced expression of the SNAI1 gene, enrichment of ALDH1^high BTICs, self-renewal capacity, and chemoresistance in TNBC experimental models. Significantly, the combination of docetaxel (DTX) with dual TGF-β and AURKA pharmacologic targeting impaired tumor relapse and the emergence of distant metastasis. We also showed in unique chemoresistant TNBC cells isolated from patient-derived TNBC brain metastasis that dual TGF-β and AURKA pharmacologic targeting reversed cancer plasticity and enhanced the sensitivity of TNBC cells to DTX-based-chemotherapy. Taken together, these findings reveal for the first time the critical role of AURKA oncogenic signaling in mediating TGF-β-induced TNBC plasticity, chemoresistance, and tumor progression.

Abstract 5091: TIMP-1 in tumor-associated fibroblasts drives tumor progression in lung adenocarcinoma through CD63 interaction

Tumor associated fibroblasts (TAFs) are important regulators of tumor growth and resistance to therapies. We have recently shown that lung TAFs in vitro respond to the antifibrotic drug nintedanib in adenocarcinoma (ADC) but not squamous cell carcinoma (SCC). We also showed that the tumor-promoting effects of TAFs are driven by different mechanisms in ADC and SCC, which remain to be elucidated. Tissue inhibitor of metalloproteinases 1 (TIMP-1) has been associated with poor prognosis in lung cancer, its expression is downregulated by nintedanib, and our preliminary results reveal that its putative receptor, CD63, is overexpressed in ADC patients compared to SCC, supporting a selective crosstalk between TAFs and cancer cells in ADC through TIMP-1 and CD63. The aim of this study was to test this hypothesis using in vitro preclinical models. Primary fibroblasts were obtained with the patient informed consent, and using protocols approved by the Ethics Committee of the Hospital Clinic. ADC-TAFs and SCC-TAFs were stimulated with TGF-β1 in the presence or absence of nintedanib, and the TIMP-1 content in their conditioned medium was determined by ELISA. TIMP-1 was knocked-down in ADC-TAFs by siRNA, and the corresponding conditioned medium was used to stimulate growth and invasion of the high-CD63 ADC cell line, H1437. Likewise, CD63 expression in H1437 cells was reduced by siRNA. Our in vitro results showed that TIMP-1 secretion induced by TGF-β1 is significantly larger in ADC-TAFs compared to SCC-TAFs. Likewise, nintedanib elicited a higher downregulation of secreted TIMP-1 in ADC-TAFs compared to SCC-TAFs. Of note, TIMP-1 from ADC-TAFs was necessary to induce growth and invasion of H1437 cells. Likewise, knocking-down CD63 in H1437 ADC cells was sufficient to reduce the growth and invasion elicited by the conditioned medium of TGF-β1 activated ADC-TAFs. Collectively, our results unveil a novel stroma-carcinoma crosstalk driven by TIMP-1 and CD63 selectively in lung ADC, and support that such heterotypic crosstalk may underlie the aberrant tumor-promoting effects of ADC-TAFs that are selectively downregulated by nintedanib.

Citation Format: Paula Duch, Marta Gabasa, Rafael Ikemori, Marselina Arshakyan, Frank Hillberg, Noemí Reguart, Derek Radisky, Jordi Alcaraz. TIMP-1 in tumor-associated fibroblasts drives tumor progression in lung adenocarcinoma through CD63 interaction [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5091.

Abstract 5099: Large-cell neuroendocrine carcinoma cells of the lung induce a tumor-promoting senescent phenotype in fibroblasts through MMP1 overexpression and TGFβ1

Tumor-associated fibroblasts (TAFs) exhibit an activated/fibrotic phenotype in all subtypes of non-small cell lung cancer. In contrast, we previously reported that lung TAFs exhibit premature senescence selectively in large cell neuroendocrine carcinoma of the lung (LCNEC), which is among the most aggressive subtypes of lung cancer. Moreover, we also reported that senescent fibroblasts enhance the growth and invasion of LCNEC cells in vitro and in vivo, and that the co-culture of LCNEC cells with normal fibroblasts was sufficient to induce fibroblast senescence. Intriguingly, whole-genome transcriptional profiling identified MMP1 as highly overexpressed in a panel of LCNEC cells versus non-LCNEC cell lines. Here we examined the role of MMP1 in LCNEC paracrine induction of fibroblast senescence.

MMP-1 expression was silenced in LCNEC cancer cell lines by shRNA, and common senescent markers were analyzed after co-culture with normal fibroblasts, including β-galactosidase staining, cyclin-dependent kinase Inhibitor 2A expression (CDKN2A) and growth arrest. In addition, the tumor-promoting effects of fibroblast conditioned medium in LCNEC growth and invasion were measured.

We confirmed that the LCNEC cell lines used in this study exhibited an increased expression of 3 neuroendocrine markers (CHGA, NCAM1 and SYP) compared to non-LCNEC cells. Induction of fibroblast senescence was confirmed after coculture with shScramble LCNEC cells. Moreover, knocking-down MMP1 in LCNEC cells was sufficient to abrogate fibroblast induced senescence upon co-culture, as well as the tumor-promoting traits of fibroblast's conditioned medium. The addition of active recombinant MMP1 (rMMP1) partially rescued the fibroblast senescent phenotype in co-culture with knocked-down MMP1 LCNEC cells, yet it was not sufficient to induce senescence when added to fibroblasts cultured alone. In contrast, treating fibroblasts with rMMP1 and the potent pro-fibrotic cytokine TGFβ1 was sufficient to induce both senescence and protumorigenic properties.

Our results unveil a process of “niche construction” by LCNEC cells that is driven by their overexpression of MMP1, which induces senescence in adjacent fibroblasts that secrete factors that enhance the growth and invasion of LCNEC cells, thereby contributing to the aggressive nature of these tumors. In addition, our results reveal a new pathologic synergy between MMP1 and TGFβ1 in eliciting fibroblast senescence and enhancing its tumor-promoting traits. Moreover, our findings support that the aberrant carcinoma cell-fibroblast crosstalk mediated by MMP1 may be a suitable therapeutic target in LCNEC, which currently lacks targeted therapies.

Citation Format: Marta Gabasa, Rafael Ikemori, Marselina Arshakyan, Evette Radisky, Noemí Reguard, Derek Radisky, Jordi Alcaraz. Large-cell neuroendocrine carcinoma cells of the lung induce a tumor-promoting senescent phenotype in fibroblasts through MMP1 overexpression and TGFβ1 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5099.

Integrated strategy combining endobronchial ultrasound with positron emission tomography to diagnose peripheral pulmonary lesions

Background

Endobronchial ultrasound‐guided transbronchial lung biopsy (EBUS‐TBLB) and fluorodeoxyglucose positron emission tomography (FDG‐PET) have been widely used in the diagnosis of peripheral pulmonary lesions (PPLs). This study was conducted to determine the diagnostic value of EBUS‐TBLB combined with FDG‐PET in the assessment of PPLs.

Methods

The clinical data of 76 patients with PPLs who received both FDG‐PET and EBUS‐TBLB from January 2016 to February 2018 were retrospectively evaluated. Further subgroup analysis was performed according to lesion diameter (≤20 mm or >20 mm). Related diagnostic indices were calculated and compared between groups.

Results

When combining EBUS‐TBLB with FDG‐PET, the diagnostic accuracy rate, sensitivity, specificity, Youden's index, positive predictive value, and negative predictive value for PPLs were 86.8%, 90.2%, 73.3%, 63.5%, 93.2%, and 64.7%, respectively. In addition, the diagnostic accuracy rate of the combined approach was significantly higher than the single EBUS‐TBLB and FDG‐PET (P < 0.01 and P < 0.05, respectively), and its Youden's index was also at a higher level. When stratified by lesion diameter, the combined approach showed a significantly higher diagnostic accuracy rate (P < 0.05) and a higher Youden's index for PPLs >20 mm than PPLs ≤20 mm. In addition, we found that positive bronchus sign and probe within the probe were two important factors conducing to enhancing the diagnostic accuracy rate for EBUS‐TBLB.

Conclusions

An integrated approach combining EBUS‐TBLB with FDG‐PET is particularly useful for diagnosing PPLs, and the improved diagnostic yields were especially evident for PPLs >20 mm.

Abstract P5-08-06: NSAID use and breast cancer risk in a retrospective cohort of women with benign breast disease

Background Prior epidemiologic studies have shown an inverse relationship of aspirin and NSAID use with breast cancer (BC) risk in the general population. Women with benign breast disease (BBD) are at an increased BC risk compared with women in the general population, and we have shown that BBD biopsies contain increased numbers of immune cells compared with normal breast tissues donated for research in the Komen Tissue Bank. We hypothesized that NSAID use among women with BBD is associated with reduced risk of BC. Methods We evaluated BC risk in relation to aspirin and NSAID use in a single institution retrospective cohort of 4,498 women who received a biopsy diagnosis of BBD between 1/1/1992 and 12/31/2001. Information on usual medication use, including average number of days used per month (0, 1-7, 8-28 and &gt;28), was collected via questionnaires mailed after identification of participants. NSAIDs were categorized into three classes: 1) Aspirin, 2) Ibuprofen (plus other prostaglandin synthesis inhibitors), and 3) COX inhibitors. BC events were captured via medical record, questionnaires, and Tumor Registry records. Medication use was evaluated for associations with clinical and pathology features. Hazard ratios (HR) and 95% confidence intervals (CI) examining associations between medication use and BC risk were estimated using Cox regression analyses, with adjustment for age and BMI at biopsy, years between biopsy and questionnaire, and pathologic features related to BC risk (severity of BBD and degree of involution in background lobules). Tests for trend examining frequency of use were calculated from ordered values (lowest to highest) in Cox models with a one degree-of-freedom linear term. We assessed BC associations with any type of NSAID use, as well as the three subclasses. Results Information on NSAID use was available for 3,089 (69%) of the participants in the cohort; these women had a median age of 49 and did not differ in BC risk from women who did not provide data on NSAID use (p=0.46). Of the 3,089 respondents, 313 (10.1%) subsequently developed BC with median follow-up of 17 years. Age was significantly associated with use of all types of NSAIDs, with increasing use in older women. BMI at the time of biopsy, severity of BBD findings, and involution in background lobules were also associated with NSAID use; thus these factors and age were adjusted for in risk association analyses. Ever users of NSAIDs (any type) had a significantly lower risk of BC than never users (HR 0.76, CI 0.59-0.98, p=0.03), and increasing frequency of NSAID use was significantly associated with lower BC risk (HRs 0.81, 0.79, and 0.70 for regular use 1-7, 8-28, and &gt;28 days/month), trend p=0.02. Analyses of drug classes revealed that ever use of ibuprofen (HR 0.61, CI 0.42-0.89, p=0.01) and ever use of COX inhibitors (HR 0.59, CI 0.39-0.89, p=0.01) were associated with decreased BC risk. COX inhibitors in particular showed a strong dose response effect with increasing use (HRs 0.97, 0.52, and 0.47 for regular use 1-7, 8-28, and &gt;28 days/month), trend p&lt;0.01. Use of aspirin was not associated with BC risk (HR 0.88, CI 0.64-1.21, p=0.44). Conclusions In this exploratory analysis, we found use of ibuprofen and other NSAIDs to be associated with decreased BC risk among women who had undergone a BBD biopsy. These findings suggest that anti-inflammatory approaches may have value in chemoprevention among women with BBD.

Citation Format: Amy Degnim, Robert Vierkant, Stacey Winham, Marlene Frost, Daniel Visscher, Jodi Carter, Suneetha Kaggal, Julie Cunningham, Teresa Allers, Tanya Hoskin, Ethan Heinzen, Celine Vachon, Keith Knutson, Keith Knutson, Derek Radisky, Mark Sherman. NSAID use and breast cancer risk in a retrospective cohort of women with benign breast disease [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-08-06.

Abstract 2021: Role of MMP1-PAR-1 crosstalk in the pro-tumorigenic senescent fibroblasts in large cell carcinoma of the lung

Tumor associated fibroblasts (TAFs) are key effector cells of cancer progression. Intriguingly, senescent TAFs have been reported in a growing list of agressive cancer subtypes including large cell carcinoma (LCC) of the lung. We previously reported that LCC cells induce fibroblast senescence in indirect co-cultures with transwells, revealing that paracrine signaling must be involved. A follow-up study identified MMP1 as an important regulatory protein in fibroblast senescence, since knocking-down MMP1 in LCC cells was sufficient to abrogate the induction of fibroblast senescence in co-cultures as well as the growth and invasion enhancement elicited by the conditioned medium of fibroblasts in LCC cells. Here we examined the potential role of the protease activated protein 1 (PAR-1) in fibroblast senescence by MMP1, since PAR-1 can be activated by MMP1 and has been reported in the stroma of lung cancer patients. We found that PAR-1 expression was down-regulated in fibroblasts that become senescent upon co-culture with LCC cells. In addition, forcing a reduced PAR-1 expression in fibroblasts by siRNA increased their expression of markers of the senescence associated secretory phenotype (SASP) during co-culture with LCC cells, whereas the percentage of senescence-associated beta-galactosidase positive fibroblasts remained largely unaffected. These results suggest that fibroblast senescence elicited by MMP1 secreted by LCC cells is mediated by processes other than PAR-1 activation and/or overexpression in fibroblasts.

Citation Format: Marta Gabasa, Rafael Ikemori, Evette Radisky, Noemí Reguart, Derek Radisky, Jordi Alcaraz. Role of MMP1-PAR-1 crosstalk in the pro-tumorigenic senescent fibroblasts in large cell carcinoma of the lung [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2021.

Abstract 651: Analysis of the immune microenvironment to advance breast cancer risk prediction and prevention

Existing risk models underperform among women who have undergone a benign breast disease (BBD) biopsy (&gt; one million performed annually in the US) and with respect to estimating the risk of aggressive BCs. We've shown that molecular pathologic analysis of BBD biopsies can improve individual risk prediction, compared with standard risk models relying on self-reported factors, and provide insights into mechanisms mediating BC risk. BC risk factors such as obesity and ethanol use are proposed to increase production of cytokines and chemokines, resulting in chronic inflammation, and leading to production of DNA damaging free radicals and growth factors (e.g., VEGF, IGFs) that activate pro-carcinogenic pathways (e.g. NF-KB and JAK/STAT). The effects of most BC risk factors on immunity are poorly understood. Further, whereas experimental models implicate immunity throughout carcinogenesis, knowledge of immune markers and mechanisms related to BC development among women is limited. Therefore, we aim to define tissue immune cell content throughout BC development, and particularly at the earliest stages, to improve risk assessment and discover immune-based prevention strategies.

Our study combines novel resources and technologies to define the immune landscape in: 1) normal breast tissues in relation to BC risk factors, 2) BBD with respect to BC risk, and 3) invasive BC in relation to neoantigen expression and molecular subtype. We will perform NanoString GeoMxTM Digital Spatial Profiling (DSP) to quantitatively map expression of key immune proteins in healthy breast tissues donated to the Komen Tissue Bank (KTB) in relation to BC risk factors and in BBD biopsies from two cohorts to predict BC risk. We will re-analyze top prognostic markers in BBD biopsies using Vectra multiplex IF staining with machine learning algorithms to refine how immune cell content and organization impacts prognosis, and assess critical immune pathways related to BBD progression with the NanoString PanCancer IO 360 panel, which provides RNA expression of 770 immune genes (13 signatures). Finally, we will evaluate immune responses in BCs categorized for predicted neoantigen load and underlying mutation type with our novel bioinformatics pipeline that enables accurate prediction of MHC class I and class II missense, fusion and frameshift mutation neoantigens generated through faulty DNA repair, aberrant DNA and RNA splicing, insertions, and deletions.

Our project demonstrates a novel approach to defining the immune processes in early stages of BC development which may improve BC risk prediction and prevention. We present a plan to comprehensively analyze immunity throughout BC development and define changes that accompany transitions from normal to BBD and BBD to BC.

Citation Format: Doug Hinerfeld, Keith Knutson, Derek Radisky, E. Aubrey Thompson, Yan Asmann, Kim McCoy, Amy Degnim, Jodi Carter, Stacey Winham, Michele Cote, Jeroen van der Laak, Mark Sherman. Analysis of the immune microenvironment to advance breast cancer risk prediction and prevention [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 651.

Abstract 994: Cancer cells induce a protumorigenic senescent phenotype in fibroblasts through MMP1 but not autophagy in large cell carcinoma of the lung

Large cell carcinoma (LCC) is among the most aggressive histologic subtypes of non-small cell lung cancer, but the mechanisms underlying such aggressive nature remain unknown. We recently showed that fibroblasts from LCC patients exhibit premature senescence in vitro, and that co-culturing LCC cells (but not cancer cells from other lung cancer subtypes) with normal fibroblasts in transwells is sufficient to induce senescence in the latter in an oxidative stress-dependent manner, supporting that fibroblast senescence is induced by a secreted factor(s) from LCC cells. Remarkably, we also found that senescent fibroblasts secrete factors that stimulate the growth and invasion of LCC cells beyond the stimulation elicited by nonsenescent fibroblasts, revealing that fibroblast senescence may contribute to the aggressive nature of LCC. Whole-genome transcriptional profiling of a panel of lung cancer cell lines identified MMP1 among the genes with larger expression in LCC compared to other lung cancer subtypes. Since MMPs can induce oxidative stress, we examined whether the excessive MMP1 expression in LCC cells was involved in the induction of fibroblast senescence in co-cultures. Knocking down MMP1 in LCC cells was sufficient to abrogate fibroblast senescence in co-cultures as well as the growth and invasion enhancement elicited by the conditioned medium of fibroblasts in LCC cells. In contrast, autophagy, which has been previously associated with fibroblast senescence in breast cancer, was not upregulated in fibroblasts upon co-culture with LCC cells. These results support that the selective aberrant expression of MMP1 in LCC cells plays a major role in their ability to induce a protumorigenic senescent phenotype in adjacent fibroblasts through a mechanism that is independent of autophagy. Moreover, our observations identify MMP1 as a potential therapeutic target against the aberrant cancer cell-fibroblast crosstalk in LCC.

Citation Format: Jordi Alcaraz, Marta Gabasa, Rafael Ikemori, Noemí Reguart, Evette Radisky, Derek Radisky. Cancer cells induce a protumorigenic senescent phenotype in fibroblasts through MMP1 but not autophagy in large cell carcinoma of the lung [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 994.

Abstract 4253: Expression profiling of paired benign and breast cancer lesions in African American women

Benign breast disease, a known risk factor for subsequent breast cancer, includes a histological spectrum of lesions that can be subdivided based on the overall impression into non-proliferative lesions, proliferative lesions without atypia, and atypical hyperplasia. Yet little is known about the molecular characteristics of benign breast tissue from African American women, who suffer from disproportionately high breast cancer mortality rates. 72 breast samples from African American women were obtained. RNA was extracted from archival formalin-fixed, paraffin-embedded (FFPE) blocks. Gene expression profiling was performed on these samples using the Affymetrix HTA2.0 exon array chip. A fit linear model using generalized least squares identified probe sets with differential expression in benign-in situ and benign-invasive breast cancer paired lesions. 36 benign and 36 breast cancer paired lesions were included in the study. In the benign-in situ set (n=20), 978 probe sets were differentially expressed (threshold: fold-change, 1.50; p &lt; 0.05). Probe sets mapped to 125 annotated genes, of which 69 (55.2%) were involved in cancer. The benign-invasive set (n=52) identified 351 differentially expressed probe sets that mapped to 84 annotated genes, of which 61 (72.6%) had known cancer significance. Genes involved in cellular growth and proliferation were significantly over-expressed in both benign-in situ and benign-invasive lesions (p-values &lt; 0.0104). In the population of 36 paired samples, differentially expressed genes were found to regulate the estrogen receptor (ESR1) through distinct network associations. Many genes are differentially expressed by benign and breast cancer lesions, and in situ/invasive histology contribute to the distinct molecular characteristics and pathways of breast malignancy. Our findings highlight the first study to assess expression profiling of paired benign and breast cancer lesions among African American women.

Citation Format: Andreana Natalie Holowatyj, Julie J. Ruterbusch, Rouba Ali-Fehmi, Sudeshna Bandyopadhyay, Christine Mehner, Melody Stallings Mann, Gregory Dyson, Derek Radisky, Michele L. Cote. Expression profiling of paired benign and breast cancer lesions in African American women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4253. doi:10.1158/1538-7445.AM2017-4253

Standardized measures of lobular involution and subsequent breast cancer risk among women with benign breast disease: a nested case-control study

Lesser degrees of terminal duct-lobular unit (TDLU) involution predict higher breast cancer risk; however, standardized measures to quantitate levels of TDLU involution have only recently been developed. We assessed whether three standardized measures of TDLU involution, with high intra/inter pathologist reproducibility in normal breast tissue, predict subsequent breast cancer risk among women in the Mayo benign breast disease (BBD) cohort. We performed a masked evaluation of biopsies from 99 women with BBD who subsequently developed breast cancer (cases) after a median of 16.9 years and 145 age-matched controls. We assessed three metrics inversely related to TDLU involution: TDLU count/mm(2), median TDLU span (microns, which approximates acini content), and median category of acini counts/TDLU (0-10; 11-20; 21-30; 31-50; >50). Associations with subsequent breast cancer risk for quartiles (or categories of acini counts) of each of these measures were assessed with multivariable conditional logistic regression to estimate odds ratios (ORs) and 95 % confidence intervals (CI). In multivariable models, women in the highest quartile compared to the lowest quartiles of TDLU counts and TDLU span measures were significantly associated with subsequent breast cancer diagnoses; TDLU counts quartile4 versus quartile1, OR = 2.44, 95 %CI 0.96-6.19, p-trend = 0.02; and TDLU spans, quartile4 versus quartile1, OR = 2.83, 95 %CI = 1.13-7.06, p-trend = 0.03. Significant associations with categorical measures of acini counts/TDLU were also observed: compared to women with median category of <10 acini/TDLU, women with >25 acini counts/TDLU were at significantly higher risk, OR = 3.40, 95 %CI 1.03-11.17, p-trend = 0.032. Women with TDLU spans and TDLU count measures above the median were at further increased risk, OR = 3.75 (95 %CI 1.40-10.00, p-trend = 0.008), compared with women below the median for both of these metrics. Similar results were observed for combinatorial metrics of TDLU acini counts/TDLU, and TDLU count. Standardized quantitative measures of TDLU counts and acini counts approximated by TDLU span measures or visually assessed in categories are independently associated with breast cancer risk. Visual assessment of TDLU numbers and acini content, which are highly reproducible between pathologists, could help identify women at high risk for subsequent breast cancer among the million women diagnosed annually with BBD in the US.

Abstract LB-364: Natural history of age-related lobular involution and impact on breast cancer risk

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 LB-378: Ankyrin repeat domain 30A as a novel molecular marker of columnar alterations in benign breast disease and subsequent breast cancer in African American women

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 4682: Standardized measures of lobular involution and subsequent breast cancer risk among women with benign breast disease

Purpose: Breast biopsies with benign findings (benign breast disease [BBD]) outnumber biopsies revealing in-situ or invasive cancer 4:1, providing an opportunity to identify histopathological features that predict breast cancer risk. Greater degrees of involution of terminal duct lobular units (TDLUs), the structures within the breast that produce milk and the primary source of breast cancer precursors, have been inversely associated with breast cancer risk among women with BBD. We recently developed measures to quantitate levels of TDLU involution, which demonstrate high inter/intra pathologist reproducibility. Here we assessed whether TDLU counts/100mm2 and median TDLU span (microns), two measures inversely related to degree of TDLU involution, are associated with subsequent breast cancer risk among women with BBD.

Methods: From the Mayo BBD cohort (n = 9,376), we evaluated benign biopsies from 99 women who later developed breast cancer (cases) and 145 age-matched controls who did not develop breast cancer. Digitized images of biopsy sections were reviewed to enumerate TDLUs/mm2 and measure median TDLU span (microns) for up to ten normal TDLUs. Breast cancer risk factors were available from questionnaires or medical records. To assess associations with breast cancer risk, subjects were categorized into quartile levels of TDLU counts and median TDLU spans, based on data from controls. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated using multivariable conditional logistic regression models, adjusted for histologic type of BBD, family history of breast cancer and menopausal hormone use.

Results: Compared to controls, women who developed breast cancer had higher median number of TDLU counts/100mm2 (28 vs 20, p = 0.03) and larger TDLU spans (300 vs 267 microns, p = 0.14). In multivariable models higher TDLU counts (quartile4 vs. quartile1, OR = 2.44, 95%CI = 0.96-6.19, ptrend = 0.02) and larger TDLU span measures (quartile4 vs. quartile1, OR = 2.83, 95%CI = 1.13-7.06, ptrend = 0.03) were associated with subsequent diagnosis of breast cancer. Combinatorial metrics of TDLU counts with median TDLU span measures identified women at higher risk; specifically, women above the median for both TDLU span and TDLU counts had an OR = 3.75 (95%CI = 1.40-10.00, ptrend = 0.008), compared with women below the median for TDLU span and TDLU counts.

Conclusion: These data show that lack of TDLU involution, as measured by increased persistence of TDLU counts, larger median TDLU spans and cross-classification using these measures was associated with increased breast cancer risk among women with BBD, extending prior work in this cohort based on other TDLU involution metrics. Future studies to identify determinants of TDLU involution, its association with breast cancer risk and its potential as an intermediate endpoint in prevention studies warrant consideration.

Citation Format: Jonine D. Figueroa, Ruth Pfeiffer, Maya Palakal, Amy C. Degnim, Derek Radisky, Lynn C. Hartmann, Marlene Frost, Melody L. Stallings Mann, Louise A. Brinton, Daphne Papathomas, Daniel Visscher, Mark E. Sherman. Standardized measures of lobular involution and subsequent breast cancer risk among women with benign breast disease. [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 4682. doi:10.1158/1538-7445.AM2015-4682

Abstract 4005: Active SHP2 mutant induces lung hyperproliferative lesions and adenoma in transgenic mice

SHP2 is a protein tyrosine phosphatase encoded by the PTPN11 gene. SHP2 is normally auto-inhibited by its regulatory N-SH2 domain. It is activated by several receptor tyrosine kinases and positively regulates the RAS/ERK and other signaling pathways by mechanisms that remain incompletely defined. Furthermore, gain-of-function activating SHP2 mutants have been found in human hematologic malignancies and solid tumors, including lung, colon, and prostate cancer. Previous studies have demonstrated the oncogenic activity of gain-of-function SHP2 mutants in the hematopoietic system. To investigate the biological functions of mutant SHP2 in vivo, we generated transgenic mice harboring a tetO-SHP2E76K transgene for tetracycline-inducible expression of the constitutively active SHP2E76K mutant. This allows us to examine the roles of the cancer-associated, Glu-76 mutant SHP2 in various tissues in bitransgenic mice. tetO-SHP2E76K mice were crossed with CCSP-rtTA or SPC-rtTA mice for inducible expression of SHP2E76K in the lung type II pneumocytes. Elevated levels of active Erk1/2 and Src were detected in the lungs of bitransgenic mice induced with doxycycline. Focal hyperplasia of bronchioloalveolar epithelial cells was observed within one month of doxycycline induction in bitransgenic mice, which progressed to more extensive atypical adenomous hyperplasia and adenoma after six months. These results suggest that Shp2 is a proto-oncogene of lung carcinoma.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4005. doi:1538-7445.AM2012-4005

A novel bioinformatics pipeline for identification and characterization of fusion transcripts in breast cancer and normal cell lines

SnowShoes-FTD, developed for fusion transcript detection in paired-end mRNA-Seq data, employs multiple steps of false positive filtering to nominate fusion transcripts with near 100% confidence. Unique features include: (i) identification of multiple fusion isoforms from two gene partners; (ii) prediction of genomic rearrangements; (iii) identification of exon fusion boundaries; (iv) generation of a 5′–3′ fusion spanning sequence for PCR validation; and (v) prediction of the protein sequences, including frame shift and amino acid insertions. We applied SnowShoes-FTD to identify 50 fusion candidates in 22 breast cancer and 9 non-transformed cell lines. Five additional fusion candidates with two isoforms were confirmed. In all, 30 of 55 fusion candidates had in-frame protein products. No fusion transcripts were detected in non-transformed cells. Consideration of the possible functions of a subset of predicted fusion proteins suggests several potentially important functions in transformation, including a possible new mechanism for overexpression of ERBB2 in a HER-positive cell line. The source code of SnowShoes-FTD is provided in two formats: one configured to run on the Sun Grid Engine for parallelization, and the other formatted to run on a single LINUX node. Executables in PERL are available for download from our web site: http://mayoresearch.mayo.edu/mayo/research/biostat/stand-alone-packages.cfm.

Abstract 4774: Epimorphin inhibits mammary epithelial cell apoptosis through induction of IKBKE

Epimorphin is a stromally produced factor that plays a role in normal mammary branching morphogenesis, but deregulated expression of epimorphin can have oncogenic consequences, although the oncogenic processes activated by epimorphin have not been elucidated. We had previously found that treatment of cultured mammary epithelial cells with epimorphin blocked activation of cell death pathways by a variety of apoptotic stimuli. These results implicated a potential role for epimorphin for inhibition of cellular apoptosis, a critical stage of tumor development. To identify potential mediators by which epimorphin could be affecting cell death pathways, we used a transcriptional profiling approach comparing mammary epithelial cells treated with epimorphin versus untreated cells. We found that epimorphin treatment led to significantly increased expression of IKBKE, which inhibits apoptosis through activation of NF-kappaB and which has recently been characterized as a key breast cancer oncogene. We found that epimorphin specifically blocks induction of apoptosis and activation of caspase-3 in cells treated with tumor necrosis factor-alpha, and that this activity was linked to epimorphin-mediated activation of IKBKE. We also found that knockdown of IKBKE blocked epimorphin-mediated induction of branching morphogenesis, implicating activation of IKBKE by epimorphin as a critical function for its normal morphogenic activities as well. These studies provide insight into an additional and unexpected linkage between mammary gland developmental processes and breast cancer progression.

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 4774. doi:10.1158/1538-7445.AM2011-4774

Abstract 2318: Induction of Rac1b by MMP-3 causes lung tumors by activating EMT

During development, epithelial cells acquire mesenchymal characteristics through a process known as epithelial-mesenchymal transition (EMT). Substantial evidence now exists that EMT-related processes play a major role in tumor progression. EMT is a focus of interest in lung cancer as loss of E-cadherin expression confers increased resistance to several types of chemotherapy. In previous studies, we found that matrix metalloproteinase-3 (MMP3) induced EMT in mouse mammary epithelial cells through induction of Rac1b, an alternatively spliced isoform of Rac1. We now show that exposure to MMPs stimulates Rac1b and induction of EMT markers in human lung cancer cell lines, and that knockdown of Rac1b blocks MMP induced EMT. We also show that Rac1b expression levels in human lung tumor biopsies is predictive of patient outcome, and that Rac1b and MMP expression levels are correlated in these samples, suggesting a direct relationship. We also describe the generation of new transgenic mouse models for which MMP3 or Rac1b is inducibly expressed in lung epithelial cells; activation of kRAS in these mice reveals that expression of MMP3 or Rac1b promotes increased tumor number, size, and progression to adenocarcinoma as well as increased expression of EMT markers vimentin, sm-actin, col1a1, and Snail. We also show that expression of Rac1b in lung epithelial cells leads to spontaneous adenocarcinoma formation. These results demonstrate a direct linkage between induction of EMT and tumor progression, implicate Rac1b as a key mediator of these processes, and demonstrate that MMPs can directly stimulate all of these events.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2318.

Neuropilin-1 upholds dedifferentiation and propagation phenotypes of renal cell carcinoma cells by activating Akt and sonic hedgehog axes

Expression of neuropilin-1 (NRP-1) has been shown in many cancer cells, but its molecular effect on tumorigenesis is largely unknown. In this report, we show that in aggressive types of renal cell carcinoma (RCC), NRP-1 is expressed at a high level. We show that after knockdown of NRP-1 by short hairpin RNA, RCC cells express significantly lower levels of MDM-2 and p63 proteins but higher levels of p53, and exhibit reduced migration and invasion. When implanted in mice, RCC cells with a reduced NRP-1 level have a statistically significant smaller tumor-forming ability than control cells. Also, NRP-1 knockdown RCC cells exhibit a more differentiated phenotype, as evidenced by the expression of epithelial-specific and kidney-specific cadherins, and the inhibition of sonic hedgehog expression participated in this effect. Inhibition of sonic hedgehog expression can be reversed by DeltaNp63alpha overexpression. Our study reveals that NRP-1 helps maintain an undifferentiated phenotype in cancer cells.

Matrix metalloproteinase-induced malignancy in mammary epithelial cells

In development, epithelial-mesenchymal transition (EMT) allows interconnected sheets of epithelial cells to reorganize and to pass into and through the surrounding extracellular matrix (ECM). In cancer, EMT-associated processes facilitate invasive growth and development of metastases. Matrix metalloproteinases (MMPs) are enzymes capable of degrading the ECM and altering cell-cell and cell-ECM interactions. MMPs are upregulated in nearly all tumor types, have been shown to induce EMT in cultured cells, and are involved in the development of tumor formation, invasion, and metastasis. We have identified the induction of Rac1b, an alternatively spliced variant of Rac1, as a key event in MMP-induced EMT. Induction of the Rac1b isoform leads to increased cellular reactive oxygen species (ROS), which causes in turn upregulation of Snail, a transcription factor previously implicated in physiological and pathological EMT. MMP/Rac1b-induced ROS also causes DNA damage and induces genomic instability. These findings reveal a new pathway in which a key element of the tumor microenvironment directly stimulates the phenotypic and genotypic alterations involved in malignant transformation, and provides many opportunities for investigation of therapeutic interventions.

Epimorphin acts to induce hair follicle anagen in C57BL/6 mice

Epimorphin is a mesenchymal morphogen that has been shown to mediate epithelial-mesenchymal signaling interactions in various organs. We now show that epimorphin functions in hair follicle morphogenesis; using a novel ex vivo organ culture assay, we define a mechanism for epimorphin signaling that may provide insight into general developmental processes. We found that epimorphin was produced by follicular mesenchymal cells and bound selectively to follicular epithelial cells, and that treatment with recombinant epimorphin could stimulate procession of hair follicles from telogen (resting stage) to anagen (growing stage). Based on analyses of epimorphin proteolytic digests that suggested a smaller peptide might be able to substitute for the full-length epimorphin molecule, we determined that pep7, a 10-amino acid peptide, was capable of inducing telogen-to-anagen transition both in the culture assay and in the mouse. That pep7 showed maximal activity only when modified with specific sulfhydryl-reactive reagents suggested that a particular structural conformation of the peptide was essential for activity; molecular dynamics studies were pursued to investigate the active peptide structure. These findings define a previously unknown morphogenic process in the hair follicle that may have applications to many other organs.

A dominant allele of PDR1 alters transition metal resistance in yeast

A yeast mutant was found to have defective growth on low iron medium despite a normal high affinity iron transport system. The phenotype results from a gain of function mutation in PDR1, which encodes a transcription factor that acts as a regulator of pleiotropic drug resistance in Saccharomyces cerevisiae. The mutant allele, PDR1(R821H), was found to result in increased expression of at least 19 genes, three of which are ATP-binding cassette (ABC) transporters. Expression of at least six genes was required to show the low iron growth defect. Wild type cells transformed with the PDR1(R821H) allele or a PDR1 dominant allele (PDR1-3) showed the low iron growth defect as well as increased resistance to drugs such as cycloheximide and oligomycin. Transformation of PDR1(R821H) into Deltaccc1 cells, which were previously shown to have increased sensitivity to high iron medium because of defective vacuolar iron storage (Li, L., Chen, O. S., Ward, D. M., and Kaplan, J. (2001) J. Biol. Chem. 276, 29515-29519), conferred resistance to high iron medium. Cells expressing PDR1(R821H) also showed increased resistance to copper and manganese because of increased metal export. These results suggest that expression of PDR1-regulated genes affects both efflux and storage of transition metals.

Nitric oxide induces gelatinase A (matrix metalloproteinase 2) during rat embryo implantation

OBJECTIVE

To evaluate a reciprocal signaling interaction initiated by embryo-derived nitric oxide (NO) to facilitate implantation by increased production of gelatinase A (matrix metalloproteinase 2, MMP2) in uterine stroma.

DESIGN

Experimental animal studies.

SETTING

Reproductive-physiology research laboratory.

ANIMAL(S)

Female syngeneic Wistar rats aged 14 weeks.

INTERVENTION(S)

Vaginal smears to confirm pregnancy. Oviductal ligature to avoid the descent of blastocysts to the uterine lumen. Plasma exudation assays to locate uterine blastocyst implantation sites. Organ cultures treated with NO donors and nitric oxide synthase (NOS) inhibitors.

MAIN OUTCOME MEASURE(S)

Expression of MMP2 and NO was assessed by Western blot and zymography of tissue extracts and by immunofluorescence of tissue sections.

RESULT(S)

An increase in MMP2 activity was found in uterine extracts in early pregnant rats and was concentrated at implantation sites. Immunolocalization experiments showed that inducible NOS was expressed on the surface of the implanting blastocyst adjacent to the uterine epithelium at the sites of increased MMP2 expression. In organ culture experiments, NO donors were found to increase, whereas NOS inhibitors were found to decrease MMP2 activity in uterine tissue sections.

CONCLUSION(S)

Blastocyst-derived NO contributes to the production of uterine-derived MMP2, an essential component of implantation and initiation of placentation.

Phenotypic reversion or death of cancer cells by altering signaling pathways in three-dimensional contexts

BACKGROUND

We previously used a three-dimensional (3D) reconstituted basement membrane (rBM) assay to demonstrate that tumorigenic HMT-3522 T4-2 human breast cells can be induced to form morphologically normal structures ("reversion") by treatment with inhibitors of beta1 integrin, the epidermal growth factor receptor (EGFR), or mitogen-activated protein kinase (MAPK). We have now used this assay to identify reversion and/or death requirements of several more aggressive human breast cancer cell lines.

METHODS

Breast tumor cell lines MCF7, Hs578T, and MDA-MB-231 were cultured in 3D rBM and treated with inhibitors of beta1 integrin, MAPK, or phosphatidylinositol 3-kinase (PI3K). MDA-MB-231 cells, which lack E-cadherin, were transfected with an E-cadherin cDNA. The extent of reversion was assessed by changes in morphology and polarity, growth in 3D rBM or soft agar, level of invasiveness, and tumor formation in nude mice.

RESULTS

All three cell lines showed partial reversion (MCF7 the greatest and Hs578T the least) of tumorigenic properties treated with a single beta1 integrin, MAPK, or PI3K inhibitor. Combined inhibition of beta1 integrin and either PI3K or MAPK resulted in nearly complete phenotypic reversion (MDA-MB-231, MCF7) or in cell death (Hs578T). E-cadherin-transfected MDA-MB-231 cells showed partial reversion, but exposure of the transfectants to an inhibitor of beta1 integrin, PI3K, or MAPK led to nearly complete reversion.

CONCLUSION

The 3D rBM assay can be used to identify signaling pathways that, when manipulated in concert, can lead to the restoration of morphologically normal breast structures or to death of the tumor cells, even highly metastatic cells. This approach may be useful to design therapeutic intervention strategies for aggressive breast cancers.

Putting tumours in context

The interactions between cancer cells and their micro- and macroenvironment create a context that promotes tumour growth and protects it from immune attack. The functional association of cancer cells with their surrounding tissues forms a new 'organ' that changes as malignancy progresses. Investigation of this process might provide new insights into the mechanisms of tumorigenesis and could also lead to new therapeutic targets.

hVPS41 is expressed in multiple isoforms and can associate with vesicles through a RING-H2 finger motif

Vps41p, the protein encoded by the yeast gene VPS41, has been shown to mediate formation of AP-3 transport vesicles from the Golgi apparatus and to facilitate the docking and fusion of lysosomal vesicles. Although both of these activities involve transient association with membrane structures, the mechanisms that mediate those interactions have not been determined. Orthologues of VPS41 have been identified in humans, Drosophila, tomato, and Arabidopsis; the degree of sequence similarity among these genes suggests a highly conserved function. Here we provide evidence that hVps41, the human homologue of Vps41p, is expressed in two isoforms that differ in that one contains a C-terminal RING-H2 sequence motif. Transient expression analysis suggests that this RING-H2 domain is responsible for membrane association. This observation was further supported by the cytosolic localization of site-specific mutants. A truncated construct containing only the hVps41 RING-H2 domain was found to associate with a class of intracellular vesicles that originated from the Golgi and showed partial coincidence with the delta subunit of the adaptor protein complex-3. Together with information from the homologous yeast system, these results suggest that hVps41 may also be involved in the formation and fusion of transport vesicles from the Golgi.

Epimorphin mediates mammary luminal morphogenesis through control of C/EBPbeta

We have shown previously that epimorphin (EPM), a protein expressed on the surface of myoepithelial and fibroblast cells of the mammary gland, acts as a multifunctional morphogen of mammary epithelial cells. Here, we present the molecular mechanism by which EPM mediates luminal morphogenesis. Treatment of cells with EPM to induce lumen formation greatly increases the overall expression of transcription factor CCAAT/enhancer binding protein (C/EBP)β and alters the relative expression of its two principal isoforms, LIP and LAP. These alterations were shown to be essential for the morphogenetic activities, since constitutive expression of LIP was sufficient to produce lumen formation, whereas constitutive expression of LAP blocked EPM-mediated luminal morphogenesis. Furthermore, in a transgenic mouse model in which EPM expression was expressed in an apolar fashion on the surface of mammary epithelial cells, we found increased expression of C/EBPβ, increased relative expression of LIP to LAP, and enlarged ductal lumina. Together, our studies demonstrate a role for EPM in luminal morphogenesis through control of C/EBPβ expression.

Tumors are unique organs defined by abnormal signaling and context

Many cancer investigations have focussed on the eradication of the cancer cell itself and in doing so, overlook the inherent complexity and heterogeneity of solid tumors. Here, we argue that, in many cases, it is the altered communication within the tumor, rather than mutations per se, that is the defining characteristic of cancer. As a result, tumorigenesis can be indirectly initiated by environmental or inherited factors that affect the stromal cells. We propose that anticancer research might be more effective if aimed at eradicating the cause of abnormality rather than just treating the end result.

Trichostatin A inhibits beta-casein expression in mammary epithelial cells

Many aspects of cellular behavior are defined by the content of information provided by association of the extracellular matrix (ECM) and with cell membrane receptors. When cultured in the presence of laminin-containing ECM and prolactin (Prl), normal mammary epithelial cells express the milk protein beta-casein. We have previously found that the minimal ECM- and Prl-responsive enhancer element BCE-1 was only active when stably integrated into chromatin, and that trichostatin A (TSA), a reagent that leads to alterations in chromatin structure, was able to activate the integrated enhancer element. We now show that endogenous beta-casein gene, which is controlled by a genetic assembly that is highly similar to that of BCE-1 and which is also activated by incubation in ECM and Prl, is instead inhibited by TSA. We provide evidence that the differing response of beta-casein and BCE-1 to TSA is neither due to an unusual effect of TSA on mammary epithelial cells, nor to secondary consequences from the expression of a separate gene, nor to a particular property of the BCE-1 construct. As a component of this investigation, we also showed that ECM mediated rapid histone deacetylation in mammary epithelial cells. These results are discussed in combination with previous work showing that TSA mediates the differentiation of many types of cancer cells but inhibits differentiation of some nonmalignant cell types.

Chloride is an allosteric effector of copper assembly for the yeast multicopper oxidase Fet3p: an unexpected role for intracellular chloride channels

GEF1 is a gene in Saccharomyces cerevisiae, which encodes a putative voltage-regulated chloride channel. gef1 mutants have a defect in the high-affinity iron transport system, which relies on the cell surface multicopper oxidase Fet3p. The defect is due to an inability to transfer Cu+ to apoFet3p within the secretory apparatus. We demonstrate that the insertion of Cu into apoFet3p is dependent on the presence of Cl-. Cu-loading of apoFet3p is favored at acidic pH, but in the absence of Cl- there is very little Cu-loading at any pH. Cl- has a positive allosteric effect on Cu-loading of apoFet3p. Kinetic studies suggest that Cl- may also bind to Fet3p and that Cu+ has an allosteric effect on the binding of Cl- to the enzyme. Thus, Cl- may be required for the metal loading of proteins within the secretory apparatus. These results may have implications in mammalian physiology, as mutations in human intracellular chloride channels result in disease.