Rapamycin Exacerbates Staphylococcus aureus Pneumonia by Inhibiting mTOR-RPS6 in Macrophages

Purpose

This study aimed to explore the effect of Rapamycin (Rapa) in Staphylococcus aureus (S. aureus) pneumonia and clarify its possible mechanism.

Methods

We investigated the effects of Rapa on S. aureus pneumonia in mouse models and in macrophages cultured in vitro. Two possible mechanisms were investigated: the mTOR-RPS6 pathway phosphorylation and phagocytosis. Furthermore, for the mechanism verification in vivo, mice with specific Mtor knockout in myeloid cells were constructed for pneumonia models.

Results

Rapa exacerbated S. aureus pneumonia in mouse models, promoting chemokines secretion and inflammatory cells infiltration in lung. In vitro, Rapa upregulated the secretion of chemokines and cytokines in macrophages induced by S. aureus. Mechanistically, the mTOR-ribosomal protein S6 (RPS6) pathway in macrophages was phosphorylated in response to S. aureus infection, and the inhibition of RPS6 phosphorylation upregulated the inflammation level. However, Rapa did not increase the phagocytic activity. Accordingly, mice with specific Mtor knockout in myeloid cells experienced more severe S. aureus pneumonia.

Conclusion

Rapa exacerbates S. aureus pneumonia by increasing the inflammatory levels of macrophages. Inhibition of mTOR-RPS6 pathway upregulates the expression of cytokines and chemokines in macrophages, thus increases inflammatory cells infiltration and exacerbates tissue damage.

Sonosensitizer Nanoplatforms Augmented Sonodynamic Therapy-Sensitizing Shikonin-Induced Necroptosis Against Hepatocellular Carcinoma

Background

Apoptosis resistance of hepatocellular carcinoma (HCC) often leads to treatment failure. Nonetheless, overcoming the resistance of HCC to apoptosis by inducing necroptosis of tumor cells to bypass the apoptotic pathway may be a promising treatment strategy. Sonodynamic therapy (SDT) has broad prospects in disease treatment because of its noninvasive characteristic and spatiotemporal control. The combination of SDT and shikonin in the treatment of HCC is expected to be a new tumor treatment method that can overcome apoptosis resistance.

Methods

In this study, the antitumor effect was evaluated using normal liver cell line WRL68, HCC cell line HepG2 and HepG2 xenograft mouse models. Indocyanine green (ICG) was loaded on nanobubbles (NBs) to construct ICG-loaded nanobubbles (ICG-NBs). Combined sonosensitizer nanoplatforms with ultrasound (US) to achieve efficient SDT, the combination of SDT and shikonin in treating HCC can activate shikonin-induced necroptosis. As a result, tumor cells that produced apoptosis resistance were destroyed by necroptosis.

Results

The results indicated a successful preparation of ICG-NBs with a uniform particle size of 273.0 ± 118.9 nm spherical structures. ICG-NB-mediated SDT, in combination with shikonin treatment, inhibited the viability, invasion, and migration of tumor cells. SDT + shikonin treatment group caused a substantial increase in necroptotic cells. The increased degree of tumor necrosis and the upregulated expression of receptor-interacting protein 3 kinase were observed in vivo studies, which indicated that the antitumor effect was accompanied by enhanced necroptosis in the SDT + shikonin treatment group.

Conclusion

ICG-NB-mediated SDT combined with shikonin inhibits the growth of HCC by increasing the necroptosis of tumor cells. Therefore, this combination therapy is a promising treatment strategy against the specific cancer.

Comprehensive Analysis of the Expression and Prognosis for RAD51 Family in Human Breast Cancer

Purpose

The RAD51 family of genes, including RAD51 and the five RAD51-like paralogs (RAD51B, RAD51C, RAD51D, XRCC2, and XRCC3), are known to be crucially associated with DNA damage repair pathway. Increasing evidence indicated that RAD51 family members were implicated in breast cancer tumorigenesis. However, their biological roles and prognostic values in breast cancer have yet to be clarified.

Methods

In this study, by using the Oncomine and GEPIA databases, we explored the transcriptional levels of RAD51 family members in breast cancer. Besides, the associations between RAD51 family expression and clinical features were evaluated by using the UALCAN database and Kaplan-Meier (KM) Plotter. We also analyzed the mutations of the RAD51 family and differentially altered genes from the cBioPortal database.

Results

We found that RAD51 mRNA was significantly elevated in breast cancer samples than in normal tissues, while XRCC2 mRNA was downregulated. Besides, a remarkable correlation was detected between the expression of RAD51/RAD51B/XRCC2 genes and the breast cancer stage. Survival analysis utilizing the KM Plotter indicated that high RAD51 and XRCC3 mRNA was associated with a poor prognosis. Conversely, RFS data suggested that high levels of RAD51B/RAD51C/RAD51D/XRCC2 were associated with a favorable prognosis. Moreover, a high genetic variation rate of RAD51C (7%) was detected in breast cancer patients.

Conclusion

Conclusively, we implied that RAD51 and XRCC3 might be potential targets for precision therapy in breast cancer and the RAD51B/RAD51C/RAD51D/XRCC2 genes have significant values for breast cancer prognosis.