Epidemiological data have linked vitamin D deficiency to the onset and severity of various cancers, including prostate cancer, and although in vitro studies have demonstrated anticancer activities for vitamin D, clinical trials provided conflicting results. To determine the impact of vitamin D signaling on prostatic precancerous lesions, we treated genetically engineered Pten((i)pe-/-) mice harboring prostatic intraepithelial neoplasia (PIN) with Gemini-72, a vitamin D analog with reported anticancer activities. We show that this analog induces apoptosis in senescent PINs, normalizes extracellular matrix remodeling by stromal fibroblasts, and reduces the prostatic infiltration of immunosuppressive myeloid-derived suppressor cells. Moreover, single-cell RNA-sequencing analysis demonstrates that while a subset of luminal cells expressing Krt8, Krt4, and Tacstd2 (termed luminal-C cells) is lost by such a treatment, antiapoptotic pathways are induced in persistent luminal-C cells. Therefore, our findings delineate the distinct responses of PINs and the microenvironment to Gemini-72, and shed light on mechanisms that limit treatment's efficacy.

BackgroundSeveral genetically modified mouse models (GEMMs) have been generated for mechanistic and therapeutic studies of mammary tumors. Although a number of cancer GEMMs have been developed, an individual model may recapitulate only some aspects of this complex disease. Indeed, breast cancer features include at least five biologically and clinically distinct intrinsic subtypes, including luminal A, luminal B, human epidermal growth factor receptor 2 (HER2)‐enriched, basal‐like, and normal‐like, with luminal A and B subtypes representing ~ 70% of breast cancers, and thus being of major clinical interest. We have engineered a novel transgenic mouse line expressing human Ki‐Ras bearing an activating mutation (Ki‐Ras(G12V)) selectively in the mammary epithelium and characterized them.MethodsTo allow conditional Ki‐Ras(G12V) expression in mammary epithelium, we generated C‐Ki‐Ras(G12V) transgenic mice that express, after Cre‐mediated DNA recombination during lactation, Ki‐Ras(G12V) under the control of the mammary tumor virus long terminal repeat (MMTV‐LTR) promoter. Tumor development was followed in 48 females after the start of lactation. Tumor characterization was performed by histopathological analysis, immunohistochemistry and real time PCR. Two cell lines were isolated from mouse mammary tumors and their phenotypes were evaluated by immunoblotting, ‘in vitro’ cell growth assays and ‘in vivo’ tumor xenograft studies.ResultsAll mice developed homogenous invasive ductal adenocarcinomas with 100% incidence within 13–35 weeks after Ki‐Ras(G12V) expression. Immunohistochemical analysis revealed high levels of estrogen receptor (ER) α in more than 90% of epithelial cells and focal progesterone receptor (PR) staining in neoplastic epithelial cells, while no HER2 staining was observed. Mammary tumor cells exhibited less than 14% nuclei positive for the proliferation marker Ki‐67, a feature that can segregate the luminal A subtype. The cytokeratin profile, as well as quantification of transcript levels of specific markers in the tumor cells, also reflected a luminal cell phenotype. Cell lines isolated from such tumors have similar characteristics as the primary tumors, are estrogen‐responsive and transplantable. Importantly, palpable tumors were detected faster than those derived from the human luminal breast cancer MCF‐7 cells (one week versus one month).ConclusionsMG‐Ki‐Ras(G12V) mice develop within a couple of months at full penetrance mammary tumors that recapitulate the most common human breast cancer subtype, classified as ductal ER‐positive invasive adenocarcinoma. Thus, this animal model together with the derived primary cancer cell line represent valuable tools with high potential of translational relevance to investigate the biology of estrogen‐dependent mammary tumors and to test various therapeutic agents.Support or Funding InformationThis work was supported by: PRIN2015 #2015B7M39T (to SA), Fondazione Italiana per la Ricerca sul Cancro (AIRC) grants: IG no. 11595 (to SA), MFAG no. 16899 (to IB), PROGRAMMA ‘FUTURO IN RICERCA’ Anno 2012 no.RBFR12FI27 (to IB), AIRC Fellowships for abroad no. 19552 (to DR), EMBO ASTF no. 18‐2010 (to RM), European Social Fund operational programme of the Calabria region (to SP), Faculté de Médecine, Université de Strasbourg (to CE) and by the Centre Nationalpour la Recherche Scientifique (CNRS), the Institut National de la Santé et de laRecherche Médicale (INSERM), the Université de Strasbourg and French state funds through the Agence Nationale de la Recherche ANR‐10‐LABX‐0030‐INRT under the frame programme Investissements d'Avenir labelled ANR‐10‐IDEX‐0002‐02.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Abstract Lymph node metastasis is an important prognosis factor in non‐small cell lung cancer (NSCLC) patients. The aim of this study was to investigate the role of epithelial to mesenchymal transition (EMT) in lymph node progression in the early stages of NSCLC. We studied a retrospective cohort of 160 consecutive surgically treated NSCLC patients with available frozen tumor samples for expression of EMT markers (CDH1, CTNNB1, CDH2, and VIMENTIN), inducers (TGFB1, c‐MET, and CAIX), and transcription factors (EMT‐TF: SNAI1, SNAI2, ZEB1, TWIST1, and TWIST2). Partial EMT was more frequent in N1‐2 (N+) vs N0 patients (P < .01). TGFB1 (P = .02) as well as SNAI2 (P < .01) and TWIST1 (P = .04) were the most differentially expressed genes in N+ tumors. In this group, ZEB1 was correlated with all EMT inducers and other EMT‐TFs were overexpressed depending on the inducers. CAIX was an independent prognostic factor for overall survival (IC 95% HR: 1.10‐5.14, P = .03). Partial EMT is involved in lymph node progression of NSCLC patients and depends on the TGFβ pathway. EMT‐TFs are differentially expressed depending on EMT inducers. CAIX might be a relevant prognostic marker in early stage NSCLC.

Appropriate ‘in vivo’ models are crucial for studying breast cancer biology and evaluating the efficacy of therapeutic agents. Thus we engineered a novel transgenic mouse line expressing the human Ki-Ras bearing an activating mutation (Ki-Ras(G12V)) selectively in the mammary epithelium after lactation. These mice develop invasive ductal adenocarcinomas with 100% incidence within 3–9 months after Ki-Ras(G12V) induction. Immunophenotyping revealed that the mammary tumors express luminal markers, are positive for estrogen and progesterone receptors, negative for HER2 and have a low proliferation index. Moreover, cell lines derived from such tumors are estrogen-responsive and, when transplanted into nude mice, form tumors that respond to the antiestrogen ICI 182780. In conclusion, the mammary tumors of these transgenic mice and the derived cell lines exhibit key features of the major form of human breast cancer, that is, luminal A subtype and thus have a high potential for breast cancer research and treatment.