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Objective Osteosarcoma (OS) is characterized by high levels of the tumour‐associated inflammatory microenvironment. Moreover, in approximately 60% of OS, telomere length is maintained by alternative lengthening of telomeres (ALT) pathway. Whether the ALT pathway can be exploited for OS therapeutic treatment and how the OS inflammatory microenvironment influences the anti‐cancer drug effect remains unknown. Here, we examined the biological effects of TMPyP4 and cisplatin in the inflammatory microenvironment of OS cells. Materials and methods Immunofluorescence in situ hybridization (IF‐FISH) and C‐circle experiments were used to detect the G‐quadruplex and ALT activity. The redox potential of single guanine, G‐quadruplex and G‐quadruplex/TMPyP4 was evaluated by the lowest unoccupied molecular orbital energy (LUMO), zeta potential and cyclic voltammetry. Cell viability, flow cytometry and apoptosis, Western blot, comet assay, adhesion, transwell and scratch experiments were performed to compare the anti‐tumour proliferation and migration effects of TMPyP4 and cisplatin in the inflammatory microenvironment. Results This study indicated that compared with cisplatin, TMPyP4 could induce the formation of human telomeres and FAK G‐quadruplex in vitro and in vivo, and TMPyP4‐treated OS cells showed fewer extrachromosomal C‐circles and fewer ALT‐associated promyelocytic leukaemia bodies. Consequently, the ALT activity and FAK‐related cell migration were suppressed by TMPyP4. Mechanistically, the formation of G‐quadruplex resulted in both lower redox potential than G within the genome and FAK transcription inhibition, and TMPyP4 could enhance this phenomenon, especially in the inflammatory microenvironment. Conclusions Our results reveal that TMPyP4 is more suitable for OS treatment than cisplatin.

Background Metastatic castration-resistant prostate cancer (CRPC) is the leading cause of death among men diagnosed with prostate cancer. Piperlongumine (PL) is a novel potential anticancer agent that has been demonstrated to exhibit anticancer efficacy against prostate cancer cells. However, the effects of PL on DNA damage and repair against CRPC have remained unclear. The aim of this study was to further explore the anticancer activity and mechanisms of action of PL against CRPC in terms of DNA damage and repair processes. Methods The effect of PL on CRPC was evaluated by MTT assay, long-term cell proliferation, reactive oxygen species assay, western blot assay, flow cytometry assay (annexin V/PI staining), β-gal staining assay and DAPI staining assay. The capacity of PL to inhibit the invasion and migration of CRPC cells was assessed by scratch-wound assay, cell adhesion assay, transwell assay and immunofluorescence (IF) assay. The effect of PL on DNA damage and repair was determined via IF assay and comet assay. Results The results showed that PL exhibited stronger anticancer activity against CRPC compared to that of taxol, cisplatin (DDP), doxorubicin (Dox), or 5-Fluorouracil (5-FU), with fewer side effects in normal cells. Importantly, PL treatment significantly decreased cell adhesion to the extracellular matrix and inhibited the migration of CRPC cells through affecting the expression and distribution of focal adhesion kinase (FAK), leading to concentration-dependent inhibition of CRPC cell proliferation and concomitantly increased cell death. Moreover, PL treatment triggered persistent DNA damage and provoked strong DNA damage responses in CRPC cells. Conclusion Collectively, our findings demonstrate that PL potently inhibited proliferation, migration, and invasion of CRPC cells and that these potent anticancer effects were potentially achieved via triggering persistent DNA damage in CRPC cells.

Common odontogenic cysts and ameloblastomas of the jaw are often associated with external root resorption of adjacent teeth. Principal findingsAmeloblastomas were eight times more likely to cause root resorption than odontogenic keratocysts while dentigerous cysts were three times more likely to cause root resorption than odontogenic keratocysts. We found a clear association between the type of lesion and the presence of external root resorption.

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in all cases of osteonecrosis of the jaw, provided that the systemic condition of the patient permits the surgical approach.