Background: The development of chemoresistance to paclitaxel and carboplatin represents a major therapeutic challenge in ovarian cancer, a disease frequently characterized by malignant ascites and extrapelvic metastasis. Microtentacles (McTNs) are tubulin-based projections observed in detached breast cancer cells. In this study, we investigated whether ovarian cancers exhibit McTNs and characterized McTN biology. Methods: We used an established lipid-tethering mechanism to suspend and image individual cancer cells. We queried a panel of immortalized serous (OSC) and clear cell (OCCC) cell lines as well as freshly procured ascites and human ovarian surface epithelium (HOSE). We assessed by Western blot β-tubulin isotype, α-tubulin post-translational modifications and actin regulatory proteins in attached/detached states. We studied clustering in suspended conditions. Effects of treatment with microtubule depolymerizing and stabilizing drugs were described. Results: Among cell lines, up to 30% of cells expressed McTNs. Four McTN morphologies (absent, symmetric-short, symmetric-long, tufted) were observed in immortalized cultures as well as ascites. McTN number/length varied with histology according to metastatic potential. Most OCCC overexpressed class III ß-tubulin. OCCC/OSC cell lines exhibited a trend towards more microtubule-stabilizing post-translational modifications of α-tubulin relative to HOSE. Microtubule depolymerizing drugs decreased the number/length of McTNs, confirming that McTNs are composed of tubulin. Cells that failed to form McTNs demonstrated differential expression of α-tubulin- and actin-regulating proteins relative to cells that form McTNs. Cluster formation is more susceptible to microtubule targeting agents in cells that form McTNs, suggesting a role for McTNs in aggregation. Conclusions: McTNs likely participate in key aspects of ovarian cancer metastasis. McTNs represent a new therapeutic target for this disease that could refine therapies, including intraperitoneal drug delivery.

Drug chemoresistance remains a major reason of treatment failure in cancer patients. In head and neck squamous cell carcinoma (HNSCC), the seventh most common cancer worldwide, cisplatin chemotherapy remains the gold standard for advanced tumors but often faces loss of responsiveness and the drawback of relapse. We previously showed that the metabolic and angiogenic factor angiopoietin-like 4 (ANGPTL4) is a molecular biomarker of oral dysplasia and HNSCC. We also found that through interaction with Neuropilin 1 (NRP1), ANGPTL4 activates proliferative and migratory pathways that contribute to HNSCC development. Using HNSCC xenografts, patient tumor-derived organoids, tumor spheroids, and HNSCC cell lines, CAL27, HN13, and HN4, here we provide evidence of the role of ANGPTL4 in the development of platinum-based chemoresistance in HNSCC through the promotion of DNA damage response (DDR) and homologous recombination (HR). ANGPTL4 enhanced these mechanisms by promoting phosphorylation of RAD51 recombinase in Tyr ^315/54 through an NRP1/ABL1-dependent mechanism. Pharmacologic inhibition of NRP1 or ABL1 reversed ANGPTL4-mediated DDR and HR, and increased HNSCC cell death in combination with cisplatin, in vitro and in vivo. Our results reveal a role for ANGPTL4 in RAD51-dependent DNA repair and suggest that ANGPTL4/NRP1/ABL1/RAD51 may serve as an alternative therapeutic target for HNSCC.

Natural killer T (NKT) cells bridge innate and adaptive immune responses and play a critical role in anti-tumor immunity. The goal of the study was to assess NKT cell and T cell function in lymphoma patients and to investigate whether specific cytokines correlate with outcomes and/or immune cell function. Patient diagnoses were confirmed by histology. NKT and T cell number and function were assessed by flow cytometry and stimulation with artificial antigen-presenting cells (aAPCs) followed by ELISA and quantitative RT-PCR (qPCR). Cytokine expression levels were compared using online databases, and protein levels in the plasma were assessed by ELISA. NKT cell activation, indicated by at least 1.5-fold IFN-γ induction over baseline following stimulation, was detected in 82% of healthy donors, compared to 44% of lymphoma patients. Lymphoma patients have significantly higher levels of circulating pro- and anti-inflammatory cytokines IL-10, IL-6, and Sema4D as compared to healthy donors. In addition, NKT cell function in the blood correlated with NKT cell function in the bone marrow in lymphoma patients. We found that aAPC-qPCR can be used to quickly assess immune cell function in cancer patients. Circulating NKT cell function positively correlated with bone marrow NKT cell function, suggesting that circulating NKT responses reflect systemic immune competence. Outcome-associated transcriptomic analyses showed that lower expression of TGF-β, IL-6, IL-10, and IFN-γ mRNA correlated with poorer clinical outcomes, whereas higher Sema4D expression was associated with worse prognosis, identifying Sema4D as a potential immunologic biomarker linked to disease progression and immune dysfunction in B cell lymphoma.