Despite the major advances in breast cancer management over the past few decades, metastatic breast cancer continues to be a major concern and the main cause of mortality associated with this disease. The Rho GTPase RAC1 has been implicated in breast cancer aggressiveness, yet the mechanisms underlying its prometastatic activity remain poorly understood. Although RAC1 overexpression is correlated with poor prognosis, our data indicate that increased abundance alone is insufficient to drive metastatic dissemination in preclinical models. While RAC1 overexpression in MMTV-ErbB2 mice accelerates primary tumor growth, it does not increase metastasis. Using complementary genetic models, we show that disrupting RAC1 SUMOylation reduces lung metastases; this uncoupling from primary tumor development is clearest in the RAC1K4R knock-in model, whereas the RAC1ΔSUMO1 transgenic mice also show partial attenuation of RAC1-driven proliferative signaling. Mechanistically, loss of SUMOylation impaired the ability of RAC1 to maintain its GTP-bound state in proinvasive contexts. To exploit this dependency, we developed a cell-permeable peptide, TAT-PRASI, that blocks RAC1 SUMOylation. TAT-PRASI decreases RAC1 activity and limits migration/invasion in vitro and metastasis in vivo while reducing the invasion of patient-derived organoids. Moreover, TAT-PRASI diminishes the RAC1-POTEE interaction, which is consistent with impaired invadopodia formation. Collectively, these findings identify SUMOylation as a specific, druggable regulator of RAC1-driven metastasis, providing a preclinical proof-of-concept for selectively targeting this posttranslational modification in metastatic breast cancer.

Within the family of protein kinases there is a subgroup of 'evolutionarily related members of the total human kinome' that are devoid (or have very limited) enzymatic activity. These proteins, so-called pseudokinases, play important functions thanks to their capacity to establish regulatory protein-protein interactions. Specifically, this opinion article focuses on a group of pseudokinases called Tribbles. Tribbles (Trbl) was originally discovered in Drosophila, followed by the subsequent identification of their orthologs in mammals (TRIB1, TRIB2, TRIB3, and STK40). Work over the last decades has shown how these proteins contribute to fine-tuning key signaling pathways involved in the regulation of proliferation, differentiation, inflammation and adaptation to nutritional changes. Accordingly, dysregulation of Tribbles proteins (TRIBs) contributes to the establishment and progression of insulin resistance, obesity, type II diabetes, atherosclerosis and cancer. Here, we will discuss some of the mechanisms by which Tribbles pseudokinases carry out their functions and the crucial importance of cell context in defining the precise role played by each of the TRIBs, with emphasis on TRIB1 and TRIB3, under different physiopathological situations.

Despite the increasing understanding of the pathogenesis of glioblastoma (GBM), treatment options for this tumor remain limited. Recently, the therapeutic potential of natural compounds has attracted great interest. Thus, dietary flavonoids quercetin (QCT) and kaempferol (KMF) were investigated as potential cytostatic agents in GBM. Moreover, the physicochemical properties of QCT and KMF, determining their bioavailability and therapeutic efficiency, were evaluated. We proved that both polyphenols significantly reduced the viability of GBM cells. We also demonstrated that both QCT and KMF evoked the cytotoxic effect in T98G cells via induction of apoptotic cell death as shown by increased activity of caspase 3/7 and caspase 9 together with an overexpression of the cleaved form of PARP. Apoptosis was additionally accompanied by the activation of stress responses in QCT- and KMF-treated cells. Both polyphenols caused oxidative stress and endoplasmic reticulum (ER) stress, as demonstrated by the increased generation of reactive oxygen species (ROS), deregulated expressions of superoxide dismutases (SOD2 and Sod1 on protein and transcriptomic levels, respectively), as well as an overexpression of ERO1α, GRP78, p-JNK, and an up-regulation of Chop, Atf4 and Atf6α genes. The antitumor effect of QCT and KMF was also confirmed in vivo, showing reduced growth of tumor xenografts in the chick chorioallantoic membrane (CAM) experiment. Moreover, electrophoretic light scattering (ELS) was used to measure the zeta potential of cell membranes upon exposition to QCT and KMF. Additionally, on the basis of existing physicochemical data, the drug-likeness score of QCT and KMF was evaluated. Analyses showed that both compounds accomplish Lipinski’s Rule of 5, and they both fit into the criteria of good central nervous system (CNS) drugs. Altogether, our data support the idea that QCT and KMF might be plausible candidates for evaluation as therapeutic agents in preclinical models of glioblastoma.

ENHANCING CRITICAL THINKING THROUGH SELF-ASSESSMENT AND PEER REVIEW IN GENETIC ENGINEERING AND SYSTEMS BIOLOGY SUBJECTS

Supplementary material and methods; Supplementary figures S1-S6; supplementary tables S1-S9

COLLABORATIVE H5P GENETIC ENGINEERING EXERCISES ON A CODEIGNITER FRAMEWORK: A GAMIFIED EXPERIENCE TO PROMOTE STUDENT INVOLVEMENT AND SELF-ASSESSMENT

Powerpoint file containing Supplementary Figures 1, 2, 3, 4, 5, 6 and 7

Supplementary Tables 1-2, Figure 1 from Cannabinoids Inhibit Glioma Cell Invasion by Down-regulating Matrix Metalloproteinase-2 Expression

The small GTPase Rac1 (Ras‐related C3 botulinum toxin substrate 1) has been implicated in cancer progression and in the poor prognosis of various types of tumors. Rac1 SUMOylation occurs during epithelial‐mesenchymal transition (EMT), and it is required for tumor cell migration and invasion. Here we identify POTEE (POTE Ankyrin domain family member E) as a novel Rac1‐SUMO1 effector involved in breast cancer malignancy that controls invadopodium formation through the activation of Rac1‐SUMO1. POTEE activates Rac1 in the invadopodium by recruiting TRIO‐GEF (triple functional domain protein), and it induces tumor cell proliferation and metastasis in vitro and in vivo. We found that the co‐localization of POTEE with Rac1 is correlated with more aggressive breast cancer subtypes. Given its role in tumor dissemination, the leading cause of cancer‐related deaths, POTEE could represent a potential therapeutic target for these types of cancer.

Supplementary Materials and Methods

Supplementary Table 1 from A Combined Preclinical Therapy of Cannabinoids and Temozolomide against Glioma

Supplementary Figures 1-11 from A Combined Preclinical Therapy of Cannabinoids and Temozolomide against Glioma

List of antibodies used in this work

H5P-PANDEMIC: COLLABORATIVE DEVELOPMENT OF INTERACTIVE AND PORTABLE EXERCISES IN A GENETIC ENGINEERING GAME

Mammalian development, adult tissue homeostasis and the avoidance of severe diseases including cancer require a properly orchestrated cell cycle, as well as error-free genome maintenance. The key cell-fate decision to replicate the genome is controlled by two major signalling pathways that act in parallel—the MYC pathway and the cyclin D–cyclin-dependent kinase (CDK)–retinoblastoma protein (RB) pathway1,2. Both MYC and the cyclin D–CDK–RB axis are commonly deregulated in cancer, and this is associated with increased genomic instability. The autophagic tumour-suppressor protein AMBRA1 has been linked to the control of cell proliferation, but the underlying molecular mechanisms remain poorly understood. Here we show that AMBRA1 is an upstream master regulator of the transition from G1 to S phase and thereby prevents replication stress. Using a combination of cell and molecular approaches and in vivo models, we reveal that AMBRA1 regulates the abundance of D-type cyclins by mediating their degradation. Furthermore, by controlling the transition from G1 to S phase, AMBRA1 helps to maintain genomic integrity during DNA replication, which counteracts developmental abnormalities and tumour growth. Finally, we identify the CHK1 kinase as a potential therapeutic target in AMBRA1-deficient tumours. These results advance our understanding of the control of replication-phase entry and genomic integrity, and identify the AMBRA1–cyclin D pathway as a crucial cell-cycle-regulatory mechanism that is deeply interconnected with genomic stability in embryonic development and tumorigenesis. AMBRA1-mediated degradation of cyclin D through CRL4–DDB1 regulates cell proliferation and prevents replication stress in neurodevelopment and cancer.

A. Saborido , M.I. de la Mata Riesco , B. Olmeda Lozano , M. Lorente Pérez , M. Arroyo Sánchez , M.J. Feito Castellano , A. Sánchez Torralba , J.M. Navarro Llorens Universidad Complutense de Madrid (SPAIN)

Information about the paper titled "A GENETIC ENGINEERING FELLOWSHIP OF THE RING: BUILDING MENTORSHIP NETWORKS FOR GENETIC ENGINEERING IN BIOCHEMISTRY AND BIOLOGY DEGREES THROUGH GAMIFICATION, INTERNATIONALIZATION AND ACCESSIBILITY" at IATED Digital Library

Background: Tribbles pseudokinase 3 (TRIB3) has been proposed to both promote and restrict cancer generation and progression. However, the precise mechanisms that determine this dual role of TRIB3 in cancer remain to be understood. In this study we aimed to investigate the role of TRIB3 in luminal breast cancer, the most frequent subtype of this malignancy. Methods: We genetically manipulated TRIB3 expression in a panel of luminal breast cancer cell lines and analyzed its impact on cell proliferation, and the phosphorylation, levels, or subcellular localization of TRIB3 and other protein regulators of key signaling pathways in luminal breast cancer. We also analyzed TRIB3 protein expression in samples from luminal breast cancer patients and performed bioinformatic analyses in public datasets. Results: TRIB3 enhanced the proliferation and AKT phosphorylation in luminal A (HER2-) but decreased them in luminal B (HER2+) breast cancer cell lines. TRIB3 negatively regulated the stability of HER2 in luminal B breast cancer cell lines. TRIB3 expression was associated with increased disease-free survival and a better response to therapy in luminal breast cancer patients. Conclusions: Our findings support the exploration of TRIB3 as a potential biomarker and therapeutic target in luminal breast cancer.

J.M. Navarro Llorens 1, M. Lorente Pérez 1, C. Blázquez Ortiz1, B. García-Fojeda García-Valdecasas 1, O. Cañadas 1, S. Castillo-Lluva 1, G. Velasco 1, F.G. Guevara Acosta 1, M. Ruiz-Ortega 2, S. Baldanta Callejo 1, L. Nogués 1, A. Sánchez Torralba 1 1Universidad Complutense de Madrid (SPAIN) 2Universidad Autónoma de Madrid (SPAIN)