Person: Janiszewska, Michalina
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Publication Response and resistance to BET bromodomain inhibitors in triple negative breast cancer
(2015) Shu, Shaokun; Lin, Charles Y.; He, Housheng Hansen; Witwicki, Robert; Tabassum, Doris P.; Roberts, Justin M.; Janiszewska, Michalina; Huh, Sung Jin; Liang, Yi; Ryan, Jeremy; Doherty, Ernest; Mohammed, Hisham; Guo, Hao; Stover, Daniel G.; Ekram, Muhammad B.; Brown, Jonathan; D'Santos, Clive; Krop, Ian; Dillon, Deborah; McKeown, Michael; Ott, Christopher; Qi, Jun; Ni, Min; Rao, Prakash K.; Duarte, Melissa; Wu, Shwu-Yuan; Chiang, Cheng-Ming; Anders, Lars; Young, Richard A.; Winer, Eric; Letai, Antony; Barry, William T.; Carroll, Jason S.; Long, Henry; Brown, Myles; Liu, X. Shirley; Meyer, Clifford; Bradner, James E; Polyak, KorneliaTriple negative breast cancer (TNBC) is a heterogeneous and clinically aggressive disease for which there is no targeted therapy1-3. BET bromodomain inhibitors, which have shown efficacy in several models of cancer4-6, have not been evaluated in TNBC. These inhibitors displace BET bromodomain proteins such as BRD4 from chromatin by competing with their acetyllysine recognition modules, leading to inhibition of oncogenic transcriptional programs7-9. Here we report the preferential sensitivity of TNBCs to BET bromodomain inhibition in vitro and in vivo, establishing a rationale for clinical investigation and further motivation to understand mechanisms of resistance. In paired cell lines selected for acquired resistance to BET inhibition from previously sensitive TNBCs, we failed to identify gatekeeper mutations, new driver events or drug pump activation. BET-resistant TNBC cells remain dependent on wild-type BRD4, which supports transcription and cell proliferation in a bromodomain-independent manner. Proteomic studies of resistant TNBC identify strong association with MED1 and hyper-phosphorylation of BRD4 attributable to decreased activity of PP2A, identified here as a principal BRD4 serine phosphatase. Together, these studies provide a rationale for BET inhibition in TNBC and present mechanism-based combination strategies to anticipate clinical drug resistance.
Publication In situ single cell analysis identifies heterogeneity for PIK3CA mutation and HER2 amplification in HER2+ breast cancer
(2015) Janiszewska, Michalina; Liu, Lin; Almendro, Vanessa; Kuang, Yanan; Paweletz, Cloud; Sakr, Rita A.; Weigelt, Britta; Hanker, Ariella B.; Chandarlapaty, Sarat; King, Tari A.; Reis-Filho, Jorge S.; Arteaga, Carlos L.; Park, So Yeon; Michor, Franziska; Polyak, KorneliaDetection of minor genetically distinct subpopulations within tumors is a key challenge in cancer genomics. Here we report STAR-FISH (Specific-To-Allele PCR – FISH), a novel method for the combined detection of single nucleotide and copy number alterations in single cells in intact archived tissues. Using this method, we assessed the clinical impact of changes in the frequency and topology of PIK3CA mutation and HER2/ERBB2 amplification within HER2+ breast cancer during neoadjuvant therapy. We found that the two genetic events are not always present within the same cell. Chemotherapy selects for PIK3CA mutant cells, a minor subpopulation in nearly all treatment-naïve samples, and modulates genetic diversity within tumors. Treatment-associated changes in spatial distribution of cellular genetic diversity correlated with poor long-term outcome following adjuvant trastuzumab therapy. Our findings support the use of in situ single-cell based methods in cancer genomics and imply that chemotherapy before HER2-targeted therapy may promote treatment resistance.