Search

Intratumoral heterogeneity poses a significant hurdle for cancer treatment, yet is under-characterized in the context of tumor invasion. Cancer cells from solid tumors can invade through two predominant modes: collective invasion, whereby cancer cells invade in multi-cellular packs or streams marked by intact cell-cell junctions; and single-cell invasion, whereby cells invade independently without intercellular adhesion. We have observed that collective and single-cell invasion co-occur within the same tumor microenvironment in triple-negative breast cancer, suggesting that invasive heterogeneity supports cooperative behavior between tumor subpopulations. To test this, we used a novel, published technique developed by the lab (SaGA) to isolate pure subpopulations of 4T1 cells that collectively invade (collectives) or single cells that invade alone (singles). 3-D spheroids of SaGA-purified collectives and singles exhibited almost exclusively collective and single-cell invasion, respectively, and these invasive phenotypes were retained over multiple passages. Integration of RNA sequencing and methylation array data obtained from RNA and DNA isolates, respectively, of collectives and singles revealed that collectives exhibit drastic overexpression and promoter hypomethylation of two laminin genes that form the laminin-332 complex, Lama3 and Lamc2. Additionally, an unbiased proteomic analysis of secreted proteins also revealed an overabundance of these laminins in collectives media. We found that singles have increased expression of integrin α6 and β4, which together have been found to specifically bind to laminin-332 to activate the Rac1 GTPase. Interestingly, our RNA sequencing data revealed a binary overexpression of a Rac1 GTPase, Prex1 in singles, suggesting that singles have enhanced Rac1 activation when compared to collectives with the potential for hyperactivation upon laminin-332 binding. Indeed, laminin-332 resulted in higher GTP-bound Rac1 in singles and subsequently increased invasion of singles in 3-D models. Additionally, laminin-332 induced cell elongation at the leading edge of singles spheroids, which was reversable by treatment with a Rac1 inhibitor. Together, our data suggests that distinct subpopulations amidst a heterogeneous tumor cooperate via laminin-332 and Rac1 to facilitate tumor invasion in metastatic triple-negative breast cancer. Citation Format: Sung Bo (Joseph) Yoon, Janna Mouw, Luxiao Chen, Hao Wu, Adam Marcus. Invasively distinct subpopulations cooperate via a laminin-332/Rac1 axis in triple-negative breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-14-01.

Liver kinase B1 (LKB1)–inactivated tumors are vulnerable to the disruption of pyrimidine metabolism, and leflunomide emerges as a therapeutic candidate because its active metabolite, A77–1726, inhibits dihydroorotate dehydrogenase, which is essential for de novo pyrimidine biosynthesis. However, it is unclear whether leflunomide inhibits LKB1-inactivated tumors in vivo, and whether its inhibitory effect on the immune system will promote tumor growth. Here, we carried out a comprehensive analysis of leflunomide treatment in various LKB1-inactivated murine xenografts, patient-derived xenografts, and genetically engineered mouse models. We also generated a mouse tumor–derived cancer cell line, WRJ388, that could metastasize to the lung within a month after subcutaneous implantation in all animals. This model was used to assess the ability of leflunomide to control distant metastasis. Leflunomide treatment shrank a HeLa xenograft and attenuated the growth of an H460 xenograft, a patient-derived xenograft, and lung adenocarcinoma in the immune-competent genetically engineered mouse models. Interestingly, leflunomide suppressed tumor growth through at least three different mechanisms. It caused apoptosis in HeLa cells, induced G1 cell-cycle arrest in H460 cells, and promoted S-phase cell-cycle arrest in WRJ388 cells. Finally, leflunomide treatment prevented lung metastasis in 78% of the animals in our novel lung cancer metastasis model. In combination, these results demonstrated that leflunomide utilizes different pathways to suppress the growth of LKB1-inactivated tumors, and it also prevents cancer metastasis at distant sites. Therefore, leflunomide should be evaluated as a therapeutic agent for tumors with LKB1 inactivation.

Supplemental Figures and Tables

Experiments have recently placed stringent constraints on the most natural incarnations of weakly interacting massive particles (WIMPs), which motivates exploring alternative dark matter (DM) candidates. One interesting possibility is that DM has mass at the MeV scale. Indirect detection of gamma rays produced in its self-annihilations is a particularly timely subject since proposed telescopes such as e-ASTROGAM are poised to revolutionize our understanding of the MeV gamma ray spectrum.This thesis presents a comprehensive analysis of how existing and future gamma ray detectors can probe three realistic simplified models of MeV DM. After employing chiral perturbation theory to write down effective Lagrangians for the DM's interactions with mesons, the relevant strongly interacting degrees of freedom at the MeV scale, the gamma-ray spectra for DM annihilation are computed in detail. The final state radiation from annihilation into leptons and charged pions is calculated exactly, and contributions to the charged pion decay spectrum are accounted for at each step of the decay chain. The electron and positron spectra are also determined in these models and used to derive accurate cosmic microwave background (CMB) constraints. A common concern is that CMB constraints rule out the possibility of detecting photons from MeV DM. This is found not to be the case over most of the parameter space of the simplified models, with e-ASTROGAM providing stronger constraints even when the DM annihilates in an s-wave. For p-wave DM, e-ASTROGAM will place bounds approaching the thermal relic cross section.

Cuboctahedral coordination cages of the general formula [Pd12L24]24+ (L = low-symmetry ligand) were analyzed theoretically and experimentally. With 350 696 potential isomers, the structural space of these assemblies is vast. Orientational self-sorting refers to the preferential formation of particular isomers within the pool of potential structures. Geometric and computational analyses predict the preferred formation of cages with a cis arrangement at the metal centers. This prediction was corroborated experimentally by synthesizing a [Pd12L24]24+ cage with a bridging 3-(4-(pyridin-4-yl)phenyl)pyridine ligand. A crystallographic analysis of this assembly showed exclusive cis coordination of the 3- and the 4-pyridyl donor groups at the Pd2+ ions.

Tetra- and hexanuclear coordination cages were obtained in reactions of [Pd(CH3CN)4](BF4)2 with low-symmetry dipyridyl ligands. In both cases, only one structurally defined complex was formed out of a vast pool of potential isomers.

Checklists and action plans are a proven mechanism for project-based collaboration. Synthesizing project-specific plans is challenging, as project managers must consider multiple sources of information, from structured surveys to semi-structured conversations with stakeholders. In a needfinding study with project managers, we identified challenges in creating action plans for teams. We built MixTAPE, a mixed-initiative system that addressed these challenges with three components: a semi-structured note-taking interface for capturing stakeholder conversations, a plan generator for automatically combining multi-source information into action plans, and classification models for assigning and prioritizing action items. We evaluated MixTAPE in an observational study of 32 website design projects. Compared to a previously unstructured process, MixTAPE generated 1.45X as many tasks that are more consistent, while reducing the plan creation time by 33.70%. Through interviews and surveys, we found that participants rate MixTAPE highly across several measures. Based on our findings, we discuss the implications and opportunities for mixed-initiative action plan creation.