Lineage of origin in rhabdomyosarcoma informs pharmacological response.

Lineage or cell of origin of cancers is often unknown and thus is not a consideration in therapeutic approaches. Alveolar rhabdomyosarcoma (aRMS) is an aggressive childhood cancer for which the cell of origin remains debated. We used conditional genetic mouse models of aRMS to activate the pathognomonic Pax3:Foxo1 fusion oncogene and inactivate p53 in several stages of prenatal and postnatal muscle development. We reveal that lineage of origin significantly influences tumor histomorphology and sensitivity to targeted therapeutics. Furthermore, we uncovered differential transcriptional regulation of the Pax3:Foxo1 locus by tumor lineage of origin, which led us to identify the histone deacetylase inhibitor entinostat as a pharmacological agent for the potential conversion of Pax3:Foxo1-positive aRMS to a state akin to fusion-negative RMS through direct transcriptional suppression of Pax3:Foxo1.

Probabilistic modeling of personalized drug combinations from integrated chemical screen and molecular data in sarcoma.

BACKGROUND: Cancer patients with advanced disease routinely exhaust available clinical regimens and lack actionable genomic medicine results, leaving a large patient population without effective treatments options when their disease inevitably progresses. To address the unmet clinical need for evidence-based therapy assignment when standard clinical approaches have failed, we have developed a probabilistic computational modeling approach which integrates molecular sequencing data with functional assay data to develop patient-specific combination cancer treatments. METHODS: Tissue taken from a murine model of alveolar rhabdomyosarcoma was used to perform single agent drug screening and DNA/RNA sequencing experiments; results integrated via our computational modeling approach identified a synergistic personalized two-drug combination. Cells derived from the primary murine tumor were allografted into mouse models and used to validate the personalized two-drug combination. Computational modeling of single agent drug screening and RNA sequencing of multiple heterogenous sites from a single patient's epithelioid sarcoma identified a personalized two-drug combination effective across all tumor regions. The heterogeneity-consensus combination was validated in a xenograft model derived from the patient's primary tumor. Cell cultures derived from human and canine undifferentiated pleomorphic sarcoma were assayed by drug screen; computational modeling identified a resistance-abrogating two-drug combination common to both cell cultures. This combination was validated in vitro via a cell regrowth assay. RESULTS: Our computational modeling approach addresses three major challenges in personalized cancer therapy: synergistic drug combination predictions (validated in vitro and in vivo in a genetically engineered murine cancer model), identification of unifying therapeutic targets to overcome intra-tumor heterogeneity (validated in vivo in a human cancer xenograft), and mitigation of cancer cell resistance and rewiring mechanisms (validated in vitro in a human and canine cancer model). CONCLUSIONS: These proof-of-concept studies support the use of an integrative functional approach to personalized combination therapy prediction for the population of high-risk cancer patients lacking viable clinical options and without actionable DNA sequencing-based therapy.

Parallel Effects of Methamphetamine on Anxiety and CCL3 in Humans and a Genetic Mouse Model of High Methamphetamine Intake.

BACKGROUND: Methamphetamine (MA) abuse causes immune dysfunction and neuropsychiatric impairment. The mechanisms underlying these deficits remain unidentified. METHODS: The effects of MA on anxiety-like behavior and immune function were investigated in mice selectively bred to voluntarily consume high amounts of MA [i.e., MA high drinking (MAHDR) mice]. MA (or saline) was administered to mice using a chronic (14-day), binge-like model. Performance in the elevated zero maze (EZM) was determined 5 days after the last MA dose to examine anxiety-like behavior. Cytokine and chemokine expressions were measured in the hippocampus using quantitative polymerase chain reaction (qPCR). Human studies were also conducted to evaluate symptoms of anxiety using the General Anxiety Disorder-7 Scale in adults with and without a history of MA dependence. Plasma samples collected from human research participants were used for confirmatory analysis of murine qPCR results using an enzyme-linked immunosorbent assay. RESULTS: During early remission from MA, MAHDR mice exhibited increased anxiety-like behavior on the EZM and reduced expression of chemokine (C-C motif) ligand 3 (ccl3) in the hippocampus relative to saline-treated mice. Human adults actively dependent on MA and those in early remission had elevated symptoms of anxiety as well as reductions in plasma levels of CCL3, relative to adults with no history of MA abuse. CONCLUSIONS: The results highlight the complex effects of MA on immune and behavioral function and suggest that alterations in CCL3 signaling may contribute to the mood impairments observed during remission from MA addiction.

A case study of personalized therapy for osteosarcoma.

BACKGROUND: Effective targeted therapies are needed in sarcomas, but the biological heterogeneity of these tumors has presented a challenge to clinical integration of small molecule inhibitors in sarcoma treatment. Here we outline a process to personalize therapy for sarcomas through a case study of a canine with spontaneous osteosarcoma. PROCEDURE: Rapid establishment of a primary tumor cell culture is described, followed by efficient functional characterization of the tumor that identified the Src inhibitor dasatinib as the most effective targeted therapy for this individual dog. RESULTS: Adjuvant dasatinib was administered for a total of 26 weeks following treatment with chemotherapy. Pharmacokinetic studies confirm that a therapeutic serum concentration was achieved at a tolerable dose of 0.75 mg/kg/day. The canine patient remains without evidence of recurrent disease 24 months following initial diagnosis. CONCLUSIONS: The approach described through this illustrative case study is broadly applicable and might be used for other solid tumors in canines as well as in humans.

Dynamic and nuclear expression of PDGFRα and IGF-1R in alveolar Rhabdomyosarcoma.

UNLABELLED: Since the advent of tyrosine kinase inhibitors as targeted therapies in cancer, several receptor tyrosine kinases (RTK) have been identified as operationally important for disease progression. Rhabdomyosarcoma (RMS) is a malignancy in need of new treatment options; therefore, better understanding of the heterogeneity of RTKs would advance this goal. Here, alveolar RMS (aRMS) tumor cells derived from a transgenic mouse model expressing two such RTKs, platelet-derived growth factor (PDGFR)α and insulin-like growth factor (IGF)-1R, were investigated by fluorescence-activated cell sorting (FACS). Sorted subpopulations that were positive or negative for PDGFRα and IGF-1R dynamically altered their cell surface RTK expression profiles as early as the first cell division. Interestingly, a difference in total PDGFRα expression and nuclear IGF-1R expression was conserved in populations. Nuclear IGF-1R expression was greater than cytoplasmic IGF-1R in cells with initially high cell surface IGF-1R, and cells with high nuclear IGF-1R established tumors more efficiently in vivo. RNA interference-mediated silencing of IGF-1R in the subpopulation of cells initially harboring higher cell surface and total IGF-1R resulted in significantly reduced anchorage-independent colony formation as compared with cells with initially lower cell surface and total IGF-1R expression. Finally, in accordance with the findings observed in murine aRMS, human aRMS also had robust expression of nuclear IGF-1R. IMPLICATIONS: RTK expression status and subcellular localization dynamics are important considerations for personalized medicine.

Rb1 loss modifies but does not initiate alveolar rhabdomyosarcoma.

BACKGROUND: Alveolar rhabdomyosarcoma (aRMS) is a myogenic childhood sarcoma frequently associated with a translocation-mediated fusion gene, Pax3:Foxo1a. METHODS: We investigated the complementary role of Rb1 loss in aRMS tumor initiation and progression using conditional mouse models. RESULTS: Rb1 loss was not a necessary and sufficient mutational event for rhabdomyosarcomagenesis, nor a strong cooperative initiating mutation. Instead, Rb1 loss was a modifier of progression and increased anaplasia and pleomorphism. Whereas Pax3:Foxo1a expression was unaltered, biomarkers of aRMS versus embryonal rhabdomyosarcoma were both increased, questioning whether these diagnostic markers are reliable in the context of Rb1 loss. Genome-wide gene expression in Pax3:Foxo1a,Rb1 tumors more closely approximated aRMS than embryonal rhabdomyosarcoma. Intrinsic loss of pRb function in aRMS was evidenced by insensitivity to a Cdk4/6 inhibitor regardless of whether Rb1 was intact or null. This loss of function could be attributed to low baseline Rb1, pRb and phospho-pRb expression in aRMS tumors for which the Rb1 locus was intact. Pax3:Foxo1a RNA interference did not increase pRb or improve Cdk inhibitor sensitivity. Human aRMS shared the feature of low and/or heterogeneous tumor cell pRb expression. CONCLUSIONS: Rb1 loss from an already low pRb baseline is a significant disease modifier, raising the possibility that some cases of pleomorphic rhabdomyosarcoma may in fact be Pax3:Foxo1a-expressing aRMS with Rb1 or pRb loss of function.