Anne R. Bresnick, Ph.D.

Our research focuses on the molecular mechanisms that regulate cell migration, invasion, and metastasis, with a particular emphasis on the calcium-binding protein S100A4, an established regulator of metastatic progression. We have shown that S100A4 interacts directly with the nonmuscle myosin-IIA motor protein and promotes myosin filament disassembly, thereby altering cytoskeletal organization and cellular motility. Using complementary biochemical, structural, cellular, and animal-model approaches, we have defined the molecular basis and functional consequences of the S100A4–myosin-IIA interaction. These studies have demonstrated that S100A4 acts not only within tumor cells but also within stromal cells, including macrophages, where it regulates chemotaxis, extracellular-matrix degradation, and invasion.

In addition to investigating how S100A4 promotes the invasive behavior of tumor cells, we are interested in its roles in normal cellular physiology. Studies using primary macrophages isolated from S100A4-knockout mice have revealed that S100A4 regulates lysosomal exocytosis, a process that is critical for macrophage-mediated degradation of the extracellular matrix. Through proteomic analyses and cell-based studies, we have identified novel candidate proteins that may mediate S100A4-dependent regulation of lysosomal exocytosis. By defining the physiological functions of S100A4 in immune and nonimmune cells, our work will establish a foundation for understanding how normal cellular mechanisms are co-opted during tumor invasion, inflammation, and metastatic progression.

A complementary translational focus of the laboratory is the discovery and development of small-molecule inhibitors of S100A4. We have developed biochemical assays to identify compounds that disrupt the interaction between S100A4 and myosin-IIA and have demonstrated that S100A4 can be inhibited through several distinct mechanisms. This work includes the development of an S100A4 biosensor that reports on protein activation and the discovery that phenothiazines inhibit the S100A4–myosin-IIA interaction by inducing S100A4 oligomerization. Our current drug-discovery efforts are exploring covalent inhibitors as a strategy for achieving potent and sustained inhibition of S100A4. This work integrates biochemical characterization, medicinal chemistry, and cellular testing to evaluate compound selectivity and target engagement and to develop improved inhibitors capable of blocking S100A4-dependent cellular activities.

We also have a longstanding collaboration with Dr. Jonathan Backer investigating the roles of phosphoinositide 3-kinases, particularly PI3Kβ, in tumor cell biology. Our studies have shown that PI3Kβ regulates cancer-relevant processes including maturation of invadopodia, extracellular matrix degradation, cell invasion and macropinocytosis. This work has identified interactions between PI3Kβ and the small GTPase Rab5, as well as between PI3Kβ and Gβγ subunits, as critical regulators of PI3Kβ-dependent signaling in tumor cells, macrophages, and platelets. Importantly, disrupting these interactions impaired PI3Kβ-dependent cellular activities and attenuated tumor metastasis in vivo. Collectively, these studies have provided insight into the context-dependent functions of PI3K isoforms and identified protein–protein interactions that may offer more selective strategies for targeting PI3Kβ in tumor progression.

Graff RC, Haimowitz A, Aguilan JT, Levine A, Zhang J, Yuan W, Roose-Girma M, Seshagiri S, Porcelli SA, Gamble MJ, Sidoli S, Bresnick AR, Backer JM. Platelet PI3Kbeta regulates breast cancer metastasis. (2024) BioRxiv Sep 14:2024.09.10.612261.

Jakubik, CT, Weckerly, CC, Hammond, GRV, Bresnick, AR, and Backer, JM. PIP3 abundance overcomes PI3K signaling selectivity in invadopodia. FEBS Letters 2022 596:417-426

Dulyaninova NG, Ruiz PD, Gamble MJ, Backer JM, Bresnick AR (2018) S100A4 regulates macrophage invasion by distinct myosin-dependent and independent mechanisms. Mol Biol Cell 29, 632-42.

Bresnick AR, Weber DJ, Zimmer DB (2015) S100 proteins in cancer. Nat Rev Cancer 15, 96-109.

RamagopalU, Dulyaninova NG, VarneyKM, WilderPT, Nallamsetty S, BrenowitzM, Weber  DJ, Almo SC, Bresnick AR (2013) Structure of the S100A4/myosin-IIA complex. BMC Struct Biol 13, 31.

Dulyaninova NG, Bresnick AR (2013) The heavy chain has its day: regulation of myosin-II assembly. Bioarchitecture 3, 77-85.

Malashkevich V, Dulyaninova NG, Ramagopal UA, Liriano MA, Varney KM, Knight D, Brenowitz M, Weber DJ, Almo SC and Bresnick AR (2010) Phenothiazines inhibit S100A4 function by inducing protein oligomerization. PNAS 107, 8605-10.

Li Z-H, Dulyaninova NG, House RP, Almo SC and Bresnick AR (2010) S100A4 regulates macrophage chemotaxis. Mol Biol Cell 21, 2598-610.

Dulyaninova NG, House RP, Betapudi V and Bresnick AR (2007) Myosin-IIA heavy chain phosphorylation regulates the motility of MDA-MB-231 carcinoma cells. Mol Biol Cell 18, 3144-55.