title: Invasive lobular carcinoma cell lines are characterized by unique estrogen-mediated gene expression patterns and altered tamoxifen response.
abstract: Invasive lobular carcinoma (ILC) is a histologic subtype of breast cancer that is frequently associated with favorable outcomes, as approximately 90% of ILC express the estrogen receptor (ER). However, recent retrospective analyses suggest that patients with ILC receiving adjuvant endocrine therapy may not benefit as much as patients with invasive ductal carcinoma. On the basis of these observations, we characterized ER function and endocrine response in ILC models. The ER-positive ILC cell lines MDA MB 134VI (MM134) and SUM44PE were used to examine the ER-regulated transcriptome via gene expression microarray analyses and ER ChIP-Seq, and to examine response to endocrine therapy. In parallel, estrogen response was assessed in vivo in the patient-derived ILC xenograft HCI-013. We identified 915 genes that were uniquely E2 regulated in ILC cell lines versus other breast cancer cell lines, and a subset of these genes were also E2 regulated in vivo in HCI-013. MM134 cells were de novo tamoxifen resistant and were induced to grow by 4-hydroxytamoxifen, as well as other antiestrogens, as partial agonists. Growth was accompanied by agonist activity of tamoxifen on ER-mediated gene expression. Though tamoxifen induced cell growth, MM134 cells required fibroblast growth factor receptor (FGFR)-1 signaling to maintain viability and were sensitive to combined endocrine therapy and FGFR1 inhibition. Our observation that ER drives a unique program of gene expression in ILC cells correlates with the ability of tamoxifen to induce growth in these cells. Targeting growth factors using FGFR1 inhibitors may block survival pathways required by ILC and reverse tamoxifen resistance.
authors.affiliation: Authors' Affiliations: Women's Cancer Research Center; Departments of Biomedical Informatics, Pharmacology and Chemical Biology, Biostatistics, Human Genetics, University of Pittsburgh; Department of Pathology, Magee-Womens Hospital, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; and Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Sikora
authors.forename: Kristine L
authors.initials: KL
authors.lastname: Cooper
authors.forename: Amir
authors.initials: A
authors.lastname: Bahreini
authors.forename: Soumya
authors.initials: S
authors.lastname: Luthra
authors.forename: Guoying
authors.initials: G
authors.lastname: Wang
authors.forename: Uma R
authors.initials: UR
authors.lastname: Chandran
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Davidson
authors.forename: David J
authors.initials: DJ
authors.lastname: Dabbs
authors.forename: Alana L
authors.initials: AL
authors.lastname: Welm
authors.forename: Steffi
authors.initials: S
authors.lastname: Oesterreich
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D018275:Carcinoma, Lobular / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D004967:Estrogens / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D061986:MCF-7 Cells; D008875:Middle Aged; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000235:genetics / Q000378:metabolism; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013629:Tamoxifen / Q000494:pharmacology*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D004967:Estrogens; D011960:Receptors, Estrogen; D013629:Tamoxifen; C496348:FGFR1 protein, human; D051496:Receptor, Fibroblast Growth Factor, Type 1