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Head and neck squamous cell carcinomas (HNSCCs) are heterogeneous tumors, well known for their frequent relapsing nature. To counter recurrence, biomarkers for early diagnosis, prognosis, or treatment response prediction are urgently needed. miRNAs can profoundly impact normal physiology and enhance oncogenesis. Among all of the miRNAs, the miR-30 family is frequently downregulated in HNSCC. Here, we determined how levels of the 3p passenger strands of miR-30a and miR-30e affect tumor behavior and clarified their functional role in LA-HNSCC. In a retrospective study, levels of miR-30a-3p and miR-30e-3p were determined in 110 patients and correlated to overall survival, locoregional relapse, and distant metastasis. miR-30a/e-3p were expressed in HNSCC cell lines and HNSCC patient-derived tumoroids (PDTs) to investigate their effect on tumor cells and their microenvironment. Both miRNAs were found to have a prognosis value since low miR-30a/e-3p expression correlates to adverse prognosis and reduces overall survival. Low expression of miR-30a/e-3p is associated with a shorter time until locoregional relapse and a shorter time until metastasis, respectively. miR-30a/e-3p expression downregulates both TGF-βR1 and BMPR2 and attenuates the survival and motility of HNSCC. Results were confirmed in PDTs. Finally, secretomes of miR-30a/e-3p-transfected HNSCC activate M1-type macrophages, which exert stronger phagocytic activities toward tumor cells. miR-30a/e-3p expression can discriminate subgroups of LA-HNSCC patients with different prognosis, making them good candidates as prognostic biomarkers. Furthermore, by targeting members of the TGF-β family and generating an immune-permissive microenvironment, they may emerge as an alternative to anti-TGF-β drugs to use in combination with immune checkpoint inhibitors.

(1) Background: Epiregulin (EREG) is a ligand of EGFR and ErB4 involved in the development and the progression of various cancers including head and neck squamous cell carcinoma (HNSCC). Its overexpression in HNSCC is correlated with short overall survival and progression-free survival but predictive of tumors responding to anti-EGFR therapies. Besides tumor cells, macrophages and cancer-associated fibroblasts shed EREG in the tumor microenvironment to support tumor progression and to promote therapy resistance. Although EREG seems to be an interesting therapeutic target, no study has been conducted so far on the consequences of EREG invalidation regarding the behavior and response of HNSCC to anti-EGFR therapies and, more specifically, to cetuximab (CTX); (2) Methods: EREG was silenced in various HNSCC cell lines. The resulting phenotype (growth, clonogenic survival, apoptosis, metabolism, ferroptosis) was assessed in the absence or presence of CTX. The data were confirmed in patient-derived tumoroids; (3) Results: Here, we show that EREG invalidation sensitizes cells to CTX. This is illustrated by the reduction in cell survival, the alteration of cell metabolism associated with mitochondrial dysfunction and the initiation of ferroptosis characterized by lipid peroxidation, iron accumulation and the loss of GPX4. Combining ferroptosis inducers (RSL3 and metformin) with CTX drastically reduces the survival of HNSCC cells but also HNSCC patient-derived tumoroids; (4) Conclusions: The loss of EREG might be considered in clinical settings as a predictive biomarker for patients that might undergo ferroptosis in response to CTX and that might benefit the most from the combination of ferroptosis inducers and CTX., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Nucleic-acid aptamers are of strong interest for diagnosis and therapy. Compared with antibodies, they are smaller, stable upon variations in temperature, easy to modify, and have higher tissue-penetration abilities. However, they have been little described as detection probes in histology studies of human tissue sections. In this study, we performed fluorescence imaging with two aptamers targeting cell-surface receptors EGFR and integrin α5β1, both involved in the aggressiveness of glioblastoma. The aptamers' cell-binding specificities were confirmed using confocal imaging. The affinities of aptamers for glioblastoma cells expressing these receptors were in the 100-300 nM range. The two aptamers were then used to detect EGFR and integrin α5β1 in human glioblastoma tissues and compared with antibody labeling. Our aptafluorescence assays proved to be able to very easily reveal, in a one-step process, not only inter-tumoral glioblastoma heterogeneity (differences observed at the population level) but also intra-tumoral heterogeneity (differences among cells within individual tumors) when aptamers with different specificities were used simultaneously in multiplexing labeling experiments. The discussion also addresses the strengths and limitations of nucleic-acid aptamers for biomarker detection in histology.

The nonreceptor tyrosine kinase FAK is a promising target for solid tumor treatment because it promotes invasion, tumor progression, and drug resistance when overexpressed. Investigating the role of FAK in human melanoma cells, we found that both in situ and metastatic melanoma cells strongly express FAK, where it controls tumor cells' invasiveness by regulating focal adhesion-mediated cell motility. Inhibiting FAK in human metastatic melanoma cells with either siRNA or a small inhibitor targeting the kinase domain impaired migration but led to increased invadopodia formation and extracellular matrix degradation. Using FAK mutated at Y397, we found that this unexpected increase in invadopodia activity is due to the lack of phosphorylation at this residue. To preserve FAK-Src interaction while inhibiting pro-migratory functions of FAK, we found that altering FAK-paxillin interaction, with either FAK mutation in the focal adhesion targeting (FAT) domain or a competitive inhibitor peptide mimicking paxillin LD domains drastically reduces cell migration and matrix degradation by preserving FAK activity in the cytoplasm. In conclusion, our data show that targeting FAK-paxillin interactions could be a potential therapeutic strategy to prevent metastasis formation, and molecules targeting this interface could be alternative to inhibitors of FAK kinase activity which display unexpected effects.