Metabolic Switch in Endocrine Resistant Estrogen Receptor Positive Breast Cancer.

Purpose: The development of endocrine resistance remains a significant challenge in the clinical management of estrogen receptor-positive () breast cancer. Metabolic reprogramming is a prominent component of endocrine resistance and a potential therapeutic intervention point. However, a limited understanding of which metabolic changes are conserved across the heterogeneous landscape of ER+ breast cancer or how metabolic changes factor into ER DNA binding patterns hinder our ability to target metabolic adaptation as a treatment strategy.

Maf1 Cooperates with Progesterone Receptor to Repress RNA Polymerase III Transcription of Select tRNAs.

Progesterone receptors (PR) can regulate transcription by RNA Polymerase III (Pol III), which transcribes small non-coding RNAs, including all transfer RNAs (tRNAs). We have previously demonstrated that PR is associated with the Pol III complex at tRNA genes and that progestins downregulate tRNA transcripts in breast tumor models. To further elucidate the mechanism of PR-mediated regulation of Pol III, we studied the interplay between PR, the Pol III repressor Maf1, and TFIIIB, a core transcription component.

Cytokeratins 5 and 17 Maintain an Aggressive Epithelial State in Basal-Like Breast Cancer.

Unlabelled: Basal-like breast cancers (BLBC) are the most common triple-negative subtype (hormone receptor and HER2 negative) with poor short-term disease outcome and are commonly identified by expression of basal cytokeratins (CK) 5 and 17. The goal of this study was to investigate whether CK5 and CK17 play a role in adverse behavior of BLBC cells. BLBC cell lines contain heterogeneous populations of cells expressing CK5, CK17, and the mesenchymal filament protein vimentin.

Integrative genome-wide analysis reveals EIF3A as a key downstream regulator of translational repressor protein Musashi 2 (MSI2).

Musashi 2 (MSI2) is an RNA binding protein (RBP) that regulates asymmetric cell division and cell fate decisions in normal and cancer stem cells. MSI2 appears to repress translation by binding to 3' untranslated regions (3'UTRs) of mRNA, but the identity of functional targets remains unknown. Here, we used individual nucleotide resolution cross-linking and immunoprecipitation (iCLIP) to identify direct RNA binding partners of MSI2 and integrated these data with polysome profiling to obtain insights into MSI2 function.

Estrogens and Progestins Cooperatively Shift Breast Cancer Cell Metabolism.

Metabolic reprogramming remains largely understudied in relation to hormones in estrogen receptor (ER) and progesterone receptor (PR) positive breast cancer. In this study, we investigated how estrogens, progestins, or the combination, impact metabolism in three ER and PR positive breast cancer cell lines. We measured metabolites in the treated cells using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS).

New generation breast cancer cell lines developed from patient-derived xenografts.

Background: Breast cancer is a highly heterogeneous disease characterized by multiple histologic and molecular subtypes. While a myriad of breast cancer cell lines have been developed over the past 60 years, estrogen receptor alpha (ER)+ disease and some mutations associated with this subtype remain underrepresented. Here we describe six breast cancer cell lines derived from patient-derived xenografts (PDX) and their general characteristics.

Cytokeratin 5 alters β-catenin dynamics in breast cancer cells.

Estrogen receptor (ER) positive breast cancers often contain subpopulations of cells that express the intermediate filament protein cytokeratin 5 (CK5). CK5+ cells are enriched in cancer stem cell (CSC) properties, can be induced by progestins, and predict poor prognosis in ER+ breast cancer. We established through CK5 knockout and overexpression in ER+ breast cancer cell lines that CK5 is important for tumorsphere formation, prompting us to speculate that CK5 has regulatory activity in CSCs.

Degenerate minigene library analysis enables identification of altered branch point utilization by mutant splicing factor 3B1 (SF3B1).

Cancer-associated mutations of the core splicing factor 3 B1 (SF3B1) result in selection of novel 3' splice sites (3'SS), but precise molecular mechanisms of oncogenesis remain unclear. SF3B1 stabilizes the interaction between U2 snRNP and branch point (BP) on the pre-mRNA. It has hence been speculated that a change in BP selection is the basis for novel 3'SS selection.

The Development and Use of Scalable Systems for Studying Aberrant Splicing in SF3B1-Mutant CLL.

Mutational landscape of CLL is now known to include recurrent non-synonymous mutations in SF3B1, a core splicing factor. About 5-10% of newly diagnosed CLL harbor these mutations which are typically limited to HEAT domains in the carboxyl-terminus of the protein. Importantly, the mutations are not specific to CLL but also present in several unrelated clonal disorders.