The Microtubule-Associated Protein Tau is expressed in several cancers, including low-grade gliomas and glioblastomas. We have previously shown that Tau is crucial for the 2D motility of several glioblastoma cell lines, including U87-MG cells. Using an RNA interference (shRNA), we tested if Tau contributed to glioblastoma in vivo tumorigenicity and analyzed its function in a 3D model of multicellular spheroids (MCS). Tau depletion significantly increased median mouse survival in an orthotopic glioblastoma xenograft model. This was accompanied by the inhibition of MCS growth and cell evasion, as well as decreased MCS compactness, implying N-cadherin mislocalization. Intracellular Signaling Array analysis revealed a defective activation of the PI3K/AKT pathway in Tau-depleted cells. Such a defect in PI3K/AKT signaling was responsible for reduced MCS growth and cell evasion, as demonstrated by the inhibition of the pathway in control MCS using LY294002 or Perifosine, which did not significantly affect Tau-depleted MCS. Finally, analysis of the glioblastoma TCGA dataset showed a positive correlation between the amount of phosphorylated Akt-Ser473 and the expression of MAPT RNA encoding Tau, underlining the relevance of our findings in glioblastoma disease. We suggest a role for Tau in glioblastoma by controlling 3D cell organization and functions via the PI3K/AKT signaling axis.

Despite being extensively studied for several decades, the microtubule-associated protein Tau has not finished revealing its secrets. For long, Tau has been known for its ability to promote microtubule assembly. A less known feature of Tau is its capability to bind to cancer-related protein kinases, suggesting a possible role of Tau in modulating microtubule-independent cellular pathways that are associated with oncogenesis. With the intention of finding new therapeutic targets for cancer, it appears essential to examine the interaction of Tau with these kinases and their consequences. This review aims at collecting the literature data supporting the relationship between Tau and cancer with a particular focus on glioblastoma tumors in which the pathological significance of Tau remains largely unexplored. We will first treat this subject from a mechanistic point of view showing the pivotal role of Tau in oncogenic processes. Then, we will discuss the involvement of Tau in dysregulating critical pathways in glioblastoma. Finally, we will outline promising strategies to target Tau protein for the therapy of glioblastoma.

Resistance to treatments is one of the leading causes of cancer therapy failure. Oxaliplatin is a standard chemotherapy used to treat metastatic colorectal cancer. However, its efficacy is greatly reduced by the development of resistances. In a previous study, we deciphered the mechanisms leading to oxaliplatin resistance and highlighted the roles played by ROS production and the p38 MAPK pathway in this phenomenon. In this report, we studied the effects of different chemotherapy molecules on our oxaliplatin-resistant cells to identify alternative treatments. Among all the studied molecules, gemcitabine was the only one to present a major cytotoxic effect on oxaliplatin-resistant cancer cells both in vivo and in vitro. However, the combination of oxaliplatin and gemcitabine did not present any major interest. Indeed, the study of combination efficiency using Chou and Talalay’s method showed no synergy between oxaliplatin and gemcitabine. Using PamGene technology to decipher gemcitabine’s effects on oxaliplatin-resistant cells, we were able to show that gemcitabine counteracts chemoresistance by strongly inhibiting the Akt and src/p38 MAPK pathways, leading to apoptosis induction and cell death. In view of these results, gemcitabine could be an interesting alternative therapy for patients with colorectal cancer not responding to oxaliplatin-based protocols such as FOLFOX.

Background/Objectives: Obesity-associated hyperleptinemia has been linked to breast cancer (BC) progression via mechanisms that remain incompletely understood. This study explores the role of leptin and its receptor (LEPR) in facilitating BC cell proliferation, migration, epithelial–mesenchymal transition (EMT), and STAT3 signaling pathway activation. Methods: We analyzed gene expression and survival data from TCGA BRCA dataset. MCF-7 and MDA-MB-231 BC cells were exposed to leptin at 10 ng/mL (lean-associated levels) and 100 ng/mL (elevated levels linked to obesity). MTT assays, colony formation tests, wound-healing and tumor spheroid dissemination experiments evaluated cell proliferation and migration. Immunofluorescence and Western blot analysis assessed changes in EMT markers and cytoskeletal alterations, while Western blotting and qPCR assessed STAT3 and NCOA1 expression and activation levels. Results: Elevated LEPR expression was linked with unfavorable prognosis in BC patients. Higher doses of leptin (100 ng/mL) significantly enhanced cellular proliferation rates and migratory capabilities, in both cell lines, and promoted EMT characteristics marked by downregulated E-cadherin and cytoskeleton structural changes. Whereas heightened JAK2/STAT3 signaling correlated with elevated leptin dosages, STAT3 inhibition using AG490 reversed leptin-induced migration while reinstating E-cadherin levels to baseline. Furthermore, leptin upregulated NCOA1, an essential STAT3 coactivator, facilitating increased expression of Cyclin D1 and VEGF target genes. Clinical positive relationships were seen between LEP/LEPR expressions and NCOA1 levels and between NCOA1 and various gene signatures related to STAT3/P-STAT3 within BC specimens. Conclusions: Obesity-associated hyperleptinemia enhances aggressiveness in BC through a mechanism involving LEPR-mediated activation pathways encompassing NCOA1/STAT3, which drive proliferation, migration, and EMT. This assigns a potential therapeutic utility for obesity-related advancements found within BC pathology.