Biological Landscape of Triple Negative Breast Cancers Expressing CTLA-4

Patients with triple-negative breast cancer (TNBC) have a poor prognosis, partly because of the absence of targeted therapies. Recognition of the key role of immune responses against cancer has allowed the advent of immunotherapy, focused on the inhibition of negative immune checkpoints, such as CTLA-4. CTLA-4 is also expressed in some cancer cells, but its activity in tumor cells is not completely understood. Thus, the aim of the present work was to determine the biological landscape and functions of CTLA-4 expressed in TNBC cells through preclinical and in silico analysis. Exploration of CTLA-4 by immunohistochemistry in 50 TNBC tumors revealed membrane and cytoplasmic expression at different intensities. Preclinical experiments, using TNBC cell lines, showed that stimulation of CTLA-4 with CD80 enhances activation of the ERK1/2 signaling pathway, while CTLA-4 blockade by Ipilimumab induces the activation of AKT and reduces cell proliferation in vitro. We then developed an analytic pipeline to define the effects of CTLA-4 in available public data that allowed us to identify four distinct tumor clusters associated with CTLA-4 activation, which are characterized by enrichment of distinctive pathways associated with cell adhesion, MAPK signaling, TGF-ß, VEGF, TNF-α, drug metabolism, ion and amino acid transport, and KRAS signaling, among others. In addition, blockade of CTLA-4 induced increased secretion of IL-2 by tumor cells, suggesting that the receptor regulates cellular functions that may impact the immune microenvironment. This is relevant because a deep characterization of immune infiltrate, conducted using public data to estimate the abundancies of immune-cell types, showed that CTLA-4-activated-like tumors present a conditional immune state similar to an escape phenotype exploited by cancer cells. Finally, by interrogating transcriptional predictors of immunotherapy response, we defined that CTLA-4 activation correlates with high immune scores related to good clinical predicted responses to anti-CTLA-4 therapy. This work sheds new light on the roles of activated CLTA-4 in the tumor compartment and suggests an important interplay between tumor CLTA-4-activated portraits and immune-infiltrating cell populations.

The Trichoderma atroviride photolyase-encoding gene is transcriptionally regulated by non-canonical light response elements

The BLR-1 and BLR-2 proteins of Trichoderma atroviride are the Neurospora crassa homologs of white collar-1 and -2, two transcription factors involved in the regulation of genes by blue light. BLR-1 and BLR-2 are essential for photoinduction of phr-1, a photolyase-encoding gene whose promoter exhibits sequences similar to well-characterized light regulatory elements of Neurospora, including the albino proximal element and the light response element (LRE). However, despite the fact that this gene has been extensively used as a blue light induction marker in Trichoderma, the function of these putative regulatory elements has not been proved. The described LRE core in N. crassa comprises two close but variably spaced GATA boxes to which a WC-1/-2 complex binds transiently upon application of a light stimulus. Using 5' serial deletions of the phr-1 promoter, as well as point mutations of putative LREs, we were able to delimit an ~ 50 bp long region mediating the transcriptional response to blue light. The identified light-responsive region contained five CGATB motifs, three of them displaying opposite polarity to canonical WCC binding sites. Chromatin immunoprecipitation experiments showed that the BLR-2 protein binds along the phr-1 promoter in darkness, whereas the application of a blue light pulse results in decreased BLR-2 binding to the promoter. Our results suggest that BLR-2 and probably BLR-1 are located on the phr-1 promoter in darkness ready to perform their function as transcriptional complex in response to light.

Comparative genome sequence analysis underscores mycoparasitism as the ancestral life style of Trichoderma

BACKGROUND

Mycoparasitism, a lifestyle where one fungus is parasitic on another fungus, has special relevance when the prey is a plant pathogen, providing a strategy for biological control of pests for plant protection. Probably, the most studied biocontrol agents are species of the genus Hypocrea/Trichoderma.

RESULTS

Here we report an analysis of the genome sequences of the two biocontrol species Trichoderma atroviride (teleomorph Hypocrea atroviridis) and Trichoderma virens (formerly Gliocladium virens, teleomorph Hypocrea virens), and a comparison with Trichoderma reesei (teleomorph Hypocrea jecorina). These three Trichoderma species display a remarkable conservation of gene order (78 to 96%), and a lack of active mobile elements probably due to repeat-induced point mutation. Several gene families are expanded in the two mycoparasitic species relative to T. reesei or other ascomycetes, and are overrepresented in non-syntenic genome regions. A phylogenetic analysis shows that T. reesei and T. virens are derived relative to T. atroviride. The mycoparasitism-specific genes thus arose in a common Trichoderma ancestor but were subsequently lost in T. reesei.

CONCLUSIONS

The data offer a better understanding of mycoparasitism, and thus enforce the development of improved biocontrol strains for efficient and environmentally friendly protection of plants.

CD43 signals induce Type One lineage commitment of human CD4+ T cells

Background

The activation and effector phenotype of T cells depend on the strength of the interaction of the TcR with its cognate antigen and additional signals provided by cytokines and by co-receptors. Lymphocytes sense both the presence of an antigen and also clues from antigen-presenting cells, which dictate the requisite response. CD43 is one of the most abundant molecules on the surface of T cells; it mediates its own signalling events and cooperates with those mediated by the T cell receptor in T cell priming. We have examined the role of CD43 signals on the effector phenotype of adult CD4⁺ and CD8⁺ human T cells, both alone and in the presence of signals from the TcR.

Results

CD43 signals direct the expression of IFNγ in human T cells. In freshly isolated CD4⁺ T cells, CD43 signals potentiated expression of the IFNγ gene induced by TcR activation; this was not seen in CD8⁺ T cells. In effector cells, CD43 signals alone induced the expression of the IFNγ gene in CD4⁺ T cells and to a lesser extent in CD8⁺ cells. The combined signals from CD43 and the TcR increased the transcription of the T-bet gene in CD4⁺ T cells and inhibited the transcription of the GATA-3 gene in both populations of T cells, thus predisposing CD4⁺ T cells to commitment to the T1 lineage. In support of this, CD43 signals induced a transient membrane expression of the high-affinity chains of the receptors for IL-12 and IFNγ in CD4⁺ T cells. CD43 and TcR signals also cooperated with those of IL-12 in the induction of IFNγ expression. Moreover, CD43 signals induced the co-clustering of IFNγR and the TcR and cooperated with TcR and IL-12 signals, triggering a co-capping of both receptors in CD4⁺ populations, a phenomenon that has been associated with a T1 commitment.

Conclusion

Our results suggest a key role for CD43 signals in the differentiation of human CD4⁺ T cells into a T1 pattern.