Metabolic Escape Routes of Cancer Stem Cells and Therapeutic Opportunities

Although improvement in early diagnosis and treatment ameliorated life expectancy of cancer patients, metastatic disease still lacks effective therapeutic approaches. Resistance to anticancer therapies stems from the refractoriness of a subpopulation of cancer cells—termed cancer stem cells (CSCs)—which is endowed with tumor initiation and metastasis formation potential. CSCs are heterogeneous and diverge by phenotypic, functional and metabolic perspectives. Intrinsic as well as extrinsic stimuli dictated by the tumor microenvironment (TME)have critical roles in determining cell metabolic reprogramming from glycolytic toward an oxidative phenotype and vice versa, allowing cancer cells to thrive in adverse milieus. Crosstalk between cancer cells and the surrounding microenvironment occurs through the interchange of metabolites, miRNAs and exosomes that drive cancer cells metabolic adaptation. Herein, we identify the metabolic nodes of CSCs and discuss the latest advances in targeting metabolic demands of both CSCs and stromal cells with the scope of improving current therapies and preventing cancer progression

Messing Up the Cancer Stem Cell Chemoresistance Mechanisms Supported by Tumor Microenvironment

Despite the recent advances in cancer patient management and in the development of targeted therapies, systemic chemotherapy is currently used as a first-line treatment for many cancer types. After an initial partial response, patients become refractory to standard therapy fostering rapid tumor progression. Compelling evidence highlights that the resistance to chemotherapeutic regimens is a peculiarity of a subpopulation of cancer cells within tumor mass, known as cancer stem cells (CSCs). This cellular compartment is endowed with tumor-initiating and metastasis formation capabilities. CSC chemoresistance is sustained by a plethora of grow factors and cytokines released by neighboring tumor microenvironment (TME), which is mainly composed by adipocytes, cancer-associated fibroblasts (CAFs), immune and endothelial cells. TME strengthens CSC refractoriness to standard and targeted therapies by enhancing survival signaling pathways, DNA repair machinery, expression of drug efflux transporters and antiapoptotic proteins. In the last years many efforts have been made to understand CSCTME crosstalk and develop therapeutic strategy halting this interplay. Here, we report the combinatorial approaches, which perturb the interaction network between CSCs and the different component of TME

Cancer cell targeting by CAR-T cells: A matter of stemness

Chimeric antigen receptor (CAR)-T cell therapy represents one of the most innovative immunotherapy approaches. The encouraging results achieved by CAR-T cell therapy in hematological disorders paved the way for the employment of CAR engineered T cells in different types of solid tumors. This adoptive cell therapy represents a selective and efficacious approach to eradicate tumors through the recognition of tumor-associated antigens (TAAs). Binding of engineered CAR-T cells to TAAs provokes the release of several cytokines, granzyme, and perforin that ultimately lead to cancer cells elimination and patient’s immune system boosting. Within the tumor mass a subpopulation of cancer cells, known as cancer stem cells (CSCs), plays a crucial role in drug resistance, tumor progression, and metastasis. CAR-T cell therapy has indeed been exploited to target CSCs specific antigens as an effective strategy for tumor heterogeneity disruption. Nevertheless, a barrier to the efficacy of CAR-T cell-based therapy is represented by the poor persistence of CAR-T cells into the hostile milieu of the CSCs niche, the development of resistance to single targeting antigen, changes in tumor and T cell metabolism, and the onset of severe adverse effects. CSCs resistance is corroborated by the presence of an immunosuppressive tumor microenvironment (TME), which includes stromal cells, cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), and immune cells. The relationship between TME components and CSCs dampens the efficacy of CAR-T cell therapy. To overcome this challenge, the double strategy based on the use of CAR-T cell therapy in combination with chemotherapy could be crucial to evade immunosuppressive TME. Here, we summarize challenges and limitations of CAR-T cell therapy targeting CSCs, with particular emphasis on the role of TME and T cell metabolic demands

Effective targeting of breast cancer stem cells by combined inhibition of Sam68 and Rad51

: Breast cancer (BC) is the second cause of cancer-related deceases in the worldwide female population. Despite the successful treatment advances, 25% of BC develops resistance to current therapeutic regimens, thereby remaining a major hurdle for patient management. Current therapies, targeting the molecular events underpinning the adaptive resistance, still require effort to improve BC treatment. Using BC sphere cells (BCSphCs) as a model, here we showed that BC stem-like cells express high levels of Myc, which requires the presence of the multifunctional DNA/RNA binding protein Sam68 for the DNA-damage repair. Analysis of a cohort of BC patients displayed that Sam68 is an independent negative factor correlated with the progression of the disease. Genetic inhibition of Sam68 caused a defect in PARP-induced PAR chain synthesis upon DNA-damaging insults, resulting in cell death of TNBC cells. In contrast, BC stem-like cells were able to survive due to an upregulation of Rad51. Importantly, the inhibition of Rad51 showed synthetic lethal effect with the silencing of Sam68, hampering the cell viability of patient-derived BCSphCs and stabilizing the growth of tumor xenografts, including those TNBC carrying BRCA mutation. Moreover, the analysis of Myc, Sam68 and Rad51 expression demarcated a signature of a poor outcome in a large cohort of BC patients. Thus, our findings suggest the importance of targeting Sam68-PARP1 axis and Rad51 as potential therapeutic candidates to counteract the expansion of BC cells with an aggressive phenotype

EBF1, MYO6 and CALR expression levels predict therapeutic response in diffuse large B-cell lymphomas

BackgroundDiffuse large B-cell lymphoma (DLBCL) is a hematological malignancy representing one-third of non-Hodgkin’s lymphoma cases. Notwithstanding immunotherapy in combination with chemotherapy (R-CHOP) is an effective therapeutic approach for DLBCL, a subset of patients encounters treatment resistance, leading to low survival rates. Thus, there is an urgent need to identify predictive biomarkers for DLBCL including the elderly population, which represents the fastest-growing segment of the population in Western countries.MethodsGene expression profiles of n=414 DLBCL biopsies were retrieved from the public dataset GSE10846. Differentially expressed genes (DEGs) (fold change >1.4, p-value <0.05, n=387) have been clustered in responder and non-responder patient cohorts. An enrichment analysis has been performed on the top 30 up-regulated genes of responder and non-responder patients to identify the signatures involved in gene ontology (MSigDB). The more significantly up-regulated DEGs have been validated in our independent collection of formalin-fixed paraffin-embedded (FFPE) biopsy samples of elderly DLBCL patients, treated with R-CHOP as first-line therapy.ResultsFrom the analysis of two independent cohorts of DLBCL patients emerged a gene signature able to predict the response to R-CHOP therapy. In detail, expression levels of EBF1, MYO6, CALR are associated with a significant worse overall survival.ConclusionsThese results pave the way for a novel characterization of DLBCL biomarkers, aiding the stratification of responder versus non-responder patients

Synaptosomes: new vesicles for neuronal mitochondrial transplantation

Background: Mitochondrial dysfunction is a critical factor in the onset and progression of neurodegenerative diseases. Recently, mitochondrial transplantation has been advised as an innovative and attractive strategy to transfer and replace damaged mitochondria. Here we propose, for the first time, to use rat brain extracted synaptosomes, a subcellular fraction of isolated synaptic terminal that contains mitochondria, as mitochondrial delivery systems. Results: Synaptosome preparation was validated by the presence of Synaptophysin and PSD95. Synaptosomes were characterized in terms of dimension, zeta potential, polydispersity index and number of particles/ml. Nile Red or CTX-FITCH labeled synaptosomes were internalized in LAN5 recipient cells by a mechanism involving specific protein–protein interaction, as demonstrated by loss of fusion ability after trypsin treatment and using different cell lines. The loading and release ability of the synaptosomes was proved by the presence of curcumin both into synaptosomes and LAN5 cells. The vitality of mitochondria transferred by Synaptosomes was demonstrated by the presence of Opa1, Fis1 and TOM40 mitochondrial proteins and JC-1 measurements. Further, synaptosomes deliver vital mitochondria into the cytoplasm of neuronal cells as demonstrated by microscopic images, increase of TOM 40, cytochrome c, Hexokinase II mitochondrial proteins, and presence of rat mitochondrial DNA. Finally, by using synaptosomes as a vehicle, healthy mitochondria restored mitochondrial function in cells containing rotenone or CCCp damaged mitochondria. Conclusions: Taken together these results suggest that synaptosomes can be a natural vehicle for the delivery of molecules and organelles to neuronal cells. Further, the replacement of affected mitochondria with healthy ones could be a potential therapy for treating neuronal mitochondrial dysfunction-related diseases.[Figure not available: see fulltext.]

Aspidiella hartii (Cockerell 1895) (Hemiptera: Diaspididae) on yam (Dioscorea spp.) tubers: a new pest regularly entering the European part of the EPPO region

Yam is an important West African crop and is an inexpensive source of carbohydrate. Many people of Central African origin living in South Italy buy imported tubers to prepare their preferred recipes. Aspidiella hartii (Cockerell) infests yam tubers marketed in Bari (South Italy). Adult female scales on tuber bark are brownish, subcircular and about 1.2 mm wide. Ventral shields (‘flags’) from dead individuals are also abundant. The pest reproduces dur- ing storage and covers the tuber. Removal of plant sap shrivels the tubers during their trade, reducing quality, viability and marketability of the product. Severe A. hartii infestation of tubers can also inhibit their resprouting or kill the plant in the country of origin. Dipping yam in concentrated pyrethroids, or organophosphate insecticide, storage in sawdust, paddy husk or wood ash or paraffin wax coating may help to control the pest, although dipping in pyrethroids or organophosphate insecticide is not allowed in Europe. The armoured scale also infests Colocasia sp. (Taro, Araceae) and Ipomoea batatas (L.) Lam. (sweet potato, Convolvulaceae) causing similar damage. The presence of A. hartii host plants in Europe and the possible host-shift of this pest to other crops in the region pose a risk for EPPO countries

Targeting of the Peritumoral Adipose Tissue Microenvironment as an Innovative Antitumor Therapeutic Strategy

The tumor microenvironment (TME) plays a key role in promoting and sustaining cancer growth. Adipose tissue (AT), due to its anatomical distribution, is a prevalent component of TME, and contributes to cancer development and progression. Cancer-associated adipocytes (CAAs), reprogrammed by cancer stem cells (CSCs), drive cancer progression by releasing metabolites and inflammatory adipokines. In this review, we highlight the mechanisms underlying the bidirectional crosstalk among CAAs, CSCs, and stromal cells. Moreover, we focus on the recent advances in the therapeutic targeting of adipocyte-released factors as an innovative strategy to counteract cancer progression

The Concerted Action of Type 2 and Type 3 Deiodinases Regulates the Cell Cycle and Survival of Basal Cell Carcinoma Cells

Thyroid hormones (THs) mediate pleiotropic cellular processes involved in metabolism, cellular proliferation, and differentiation. The intracellular hormonal environment can be tailored by the type 1 and 2 deiodinase enzymes D2 and D3, which catalyze TH activation and inactivation respectively. In many cellular systems, THs exert well-documented stimulatory or inhibitory effects on cell proliferation; however, the molecular mechanisms by which they control rates of cell cycle progression have not yet been entirely clarified. We previously showed that D3 depletion or TH treatment influences the proliferation and survival of basal cell carcinoma (BCC) cells. Surprisingly, we also found that BCC cells express not only sustained levels of D3 but also robust levels of D2. The aim of the present study was to dissect the contribution of D2 to TH metabolism in the BCC context, and to identify the molecular changes associated with cell proliferation and survival induced by TH and mediated by D2 and D3

Dual Inhibition of Myc Transcription and PI3K Activity Effectively Targets Colorectal Cancer Stem Cells

Despite advances in the curative approach, the survival rate of advanced colorectal cancer (CRC) patients is still poor, which is likely due to the emergence of cancer cell clones resistant to the available therapeutic options. We have already shown that CD44v6-positive CRC stem cells (CR-CSCs) are refractory toward standard anti-tumor therapeutic agents due to the activation of the PI3K pathway together with high HER2 expression levels. Tumor microenvironmental cytokines confer resistance to CR-CSCs against HER2/PI3K targeting by enhancing activation of the MAPK pathway. Here, we show that the CSC compartment, spared by BRAF inhibitor-based targeted therapy, is associated with increased expression levels of CD44v6 and Myc and retains boosted clonogenic activity along with residual tumorigenic potential. Inhibition of Myc transcription, downstream of the MAPK cascade components, and PI3K pathway activity was able to overcome the protective effects of microenvironmental cytokines, affecting the survival and the clonogenic activity of CR-CSCs, regardless of their mutational background. Likewise, the double targeting induced stabilization of mouse tumor avatars. Altogether, these data outline the rationale for dual kinase targeting of CR-CSCs to prevent their adaptive response, which would lead to disease progression