CD4+ CD25+ regulatory T cells (Treg), an essential subset for preventing autoimmune diseases, is implicated as a negative regulator in anti-tumor immunity. We found that metformin (Met) reduced tumor-infiltrating Treg (Ti-Treg), particularly the terminally-differentiated CD103+ KLRG1+ population, and also decreased effector molecules such as CTLA4 and IL-10. Met inhibits the differentiation of naïve CD4+ T cells into inducible Treg (iTreg) by reducing forkhead box P3 (Foxp3) protein, caused by mTORC1 activation that was determined by the elevation of phosphorylated S6 (pS6), a downstream molecule of mTORC1. Rapamycin and compound C, an inhibitor of AMP-activated protein kinase (AMPK) restored the iTreg generation, further indicating the involvement of mTORC1 and AMPK. The metabolic profile of iTreg, increased Glut1-expression, and reduced mitochondrial membrane-potential and ROS production of Ti-Treg aided in identifying enhanced glycolysis upon Met-treatment. The negative impact of Met on Ti-Treg may help generation of the sustained antitumor immunity.

CD11b + myeloid subpopulations, including myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs), play crucial roles in the suppression of T-cell-mediated anti-tumor immunity. Regulation of these cell types is a primary goal for achieving efficient cancer immunotherapy. We found that metformin (Met) induces CD11b + -cell-mediated growth inhibition of a K7M2neo osteosarcoma independent of T cells, as growth inhibition of K7M2neo was still observed in wild-type (WT) mice depleted of T cells by antibodies and in SCID; this contrasted with the effect of Met on Meth A fibrosarcoma, which was entirely T-cell-dependent. Moreover, the inhibitory effect seen in SCID was abrogated by anti-CD11b antibody injection. PMN-MDSCs were significantly reduced in both spleens and tumors following Met treatment. In TAMs, production of IL-12 and TNF-α, but not IL-10, became apparent, and elevation of MHC class II with reduction of CD206 was observed, indicating a shift from an M2- to M1-like phenotype via Met administration. Metabolically, Met treatment decreased basal respiration and the oxygen consumption rate (OCR)/extracellular acidification rate (ECAR) ratio of CD11b + cells in tumors, but not in the spleen. In addition, decreased reactive oxygen species (ROS) production and proton leakage in MDSCs and TAMs were consistently observed in tumors. Uptake of both 2-deoxy-2- d -glucose (2-NBDG) and BODIPY® decreased in MDSCs, but only BODIPY® incorporation was decreased in TAMs. Overall, our results suggest that Met redirects the metabolism of CD11b + cells to lower oxidative phosphorylation (OXPHOS) while elevating glycolysis, thereby pushing the microenvironment to a state that inhibits the growth of certain tumors.

Low-intensity pulsed ultrasound (LIPUS) has been used as an adjunct to fracture healing therapies, but the mechanisms underlying its action are not known. We reported that sonic hedgehog (SHH) signaling was activated in osteoblasts at the dynamic remodeling site of a bone fracture. Mechanical stimulation is a crucial factor in bone remodeling, and it is related to the primary cilia as a sensor of hedgehog signaling. Here we observed that LIPUS promoted callus formation in accord with Gli2-positive cells after 14 days at the mouse femur fractured site compared with a control group. An immunofluorescence analysis showed that the numbers of primary cilia and cilia/osterix double-positive osteoblasts were increased at the fracture site by LIPUS. LIPUS stimulated not only the number and the length of primary cilia, but also the levels of ciliated protein, Ift88 mRNA, and SHH, Gli1, and Gli2 in MC3T3-E1 cells. Further experiments revealed that LIPUS stimulated osteogenic differentiation in the presence of smoothened agonist (SAG) treatment. These results indicate that LIPUS stimulates osteogenic differentiation and the maturation of osteoblasts by a primary cilium-mediated activation of hedgehog signaling.

Graphical abstract

Our results suggest that peripheral sensory nerve-derived TAC3 may affect gingival oral squamous cell carcinoma cells through TACR3 in the bone matrix.

These findings suggest that OSCC-derived SHH stimulates angiogenesis at the tumor invasive front.

Platinum-based antitumor agents have been widely used to treat head and neck squamous cell carcinoma (HNSCC) and numerous other malignancies. Cisplatin is the most frequently used platinum-based antitumor agent, however drug resistance and numerous undesirable side effects limit its clinical efficacy for cancer patients. Cancer cells discharge cisplatin into the extracellular space via copper transporters such as ATPase copper transporting beta (ATP7B) in order to escape from cisplatin-induced cell death. In the present study, it was demonstrated for the first time that the copper chelator ammonium tetrathiomolybdate (TM) has several promising effects on cisplatin and HNSCC. First, TM suppressed the ATP7B expression in HNSCC cell lines in vitro, thereby enhancing the accumulation and apoptotic effect of cisplatin in the cancer cells. Next, it was revealed that TM enhanced the antitumor effect of cisplatin in HNSCC cell tumor progression in a mouse model of bone invasion, which is important since HNSCC cells frequently invade to facial bone. Finally, it was demonstrated that TM was able to overcome the cisplatin resistance of a human cancer cell line, A431, via ATP7B depression in vitro.

Lower third molar removal is the most commonly performed dental surgical procedure. Nevertheless, it is difficult to ensure that all the informed consent forms given to patients are based on the best evidence as many newer publications could change the conclusions of previous research. Therefore, the goal of this review article is to cover existing meta‐analyses, randomized control trials, and related articles in order to collect data for improved and more current informed consent.