Metastasis of breast cancer, especially to the brain, is the major cause of mortality. The inability of anti-cancer agents to cross the blood-brain-barrier represents a critical challenge for successful treatment. In the current study, we investigated the anti-metastatic potential of penfluridol (PF), an antipsychotic drug frequently prescribed for schizophrenia with anti-cancer activity. We show that PF induced apoptosis and reduced the survival of several metastatic triple negative breast cancer (TNBC) cell lines. Additionally, PF treatment significantly reduced the expression of integrinα6, integrin β4, Fak, Paxillin, Rac1/2/3, and ROCK1 in vitro. We further evaluated the efficacy of PF in three different in vivo tumor models. We demonstrate that PF administration to an orthotopic model of breast cancer suppressed tumor growth by 49%. On the other hand, PF treatment inhibited the growth of metastatic brain tumors introduced by intracardiac or intracranial injection of breast cancer cells by 90% and 72%, respectively. PF-treated tumors from all three models exhibited reduced integrinβ4 and increased apoptosis. Moreover, chronic administration of PF failed to elicit significant toxic or behavioral side effects in mice. Taken together, our result indicate that PF effectively reduces the growth of primary TNBC tumors and especially metastatic growth in the brain by inhibiting integrin signaling, and prompt further preclinical investigation into repurposing PF for the treatment of metastatic TNBC.

Translocations of the mixed lineage leukemia (MLL) gene occur in 60-80% of all infant acute leukemias and are markers of poor prognosis. MLL-AF9 and other MLL fusion proteins aberrantly recruit epigenetic regulatory proteins, including histone deacetylases (HDACs), histone methyltransferases, bromodomain-containing proteins, and transcription elongation factors to mediate chromatin remodeling and regulate protumorigenic gene expression programs. We conducted a small molecule inhibitor screen to test the ability of candidate pharmacologic agents targeting epigenetic and transcriptional regulatory proteins to induce apoptosis in leukemic cells derived from genetically engineered mouse models of MLL-AF9-driven AML. We found that the CDK inhibitor dinaciclib and HDAC inhibitor panobinostat were the most potent inducers of apoptosis in short term in vitro assays. Treatment of MLL-rearranged leukemic cells with dinaciclib resulted in rapidly decreased expression of the pro-survival protein Mcl-1, and accordingly, overexpression of Mcl-1 protected AML cells from dinaciclib-induced apoptosis. Administration of dinaciclib to mice bearing MLL-AF9-driven human and mouse leukemias elicited potent antitumor responses and significantly prolonged survival. Collectively, these studies highlight a new therapeutic approach to potentially overcome the resistance of MLL-rearranged AML to conventional chemotherapies, and prompt further clinical evaluation of CDK inhibitors in AML patients harboring MLL fusion proteins.

Data accumulating over the last 20 years support the notion that some transmembrane receptors are activated not only by their respective ligands but also, differentially, by the withdrawal or absence of these same ligands. In this latter setting, these receptors actively trigger apoptosis. They have been dubbed dependence receptors because their expression confers a state of ligand dependence for survival on the expressing cells. Twenty of these receptors have been identified to date, and several have been shown to inhibit tumor progression by inducing apoptosis. As a corollary, these receptors, or their transduced death signals, are frequently silenced in cancer cells as a selective mechanism to prevent cell death, allowing invasion and metastasis. Drugs aimed at inducing programmed cell death in neoplastic cells by re-engaging the proapoptotic activity induced by unliganded dependence receptors are in late-stage preclinical tests, poised for clinical evaluation. This approach may offer novel opportunities for patient treatments. In this review, we discuss the implications of dependence receptors in limiting cancer progression and address the therapeutic perspectives brought to light by this paradigm. Cancer Res; 75(24); 1–5. ©2015 AACR.

Modern cancer therapy/care involves the integration of basic, clinical, and population-based research professionals using state-of-the-art science to achieve the best possible patient outcomes. A well-integrated team of basic, clinical, and population science professionals and educators working with a fully engaged group of creative junior investigators and trainees provides a structure to achieve these common goals. To this end, the structure provided by cancer-focused educational programs can create the integrated culture of academic medicine needed to reduce the burden of cancer on society. This summary outlines fundamental principles and potential best practice strategies for the development of integrated educational programs directed at achieving a work force of professionals that broadly appreciate the principals of academic medicine spanning the breadth of knowledge necessary to advance the goal of improving the current practice of cancer care medicine. Cancer Res; 75(24); 1–4. ©2015 AACR.