Silencing Proteasome 26S Subunit ATPase 2 (PSMC2) Protects the Osteogenic Differentiation In Vitro and Osteogenesis In Vivo

Tianhe Zhuifeng Gao reverses inflammatory response and attenuates bone/cartilage destruction in rheumatoid arthritis via PSMC2-RUNX2-COL1A1 axis based on transcriptional regulatory network analysis and experimental validation

BACKGROUND

Tianhe Zhuifeng Gao (TZG) is an authorized Chinese patent drug with satisfying clinical efficacy, especially for RA patients with cold-dampness syndrome. However, its underlying pharmacological mechanisms remain unclear.

METHOD

Anti-arthritic effects of TZG were evaluated using an adjuvant-induced arthritis (AIA) rat model. Transcriptional regulatory network analysis based on synovial tissues obtained from AIA rats, combining with our previous analysis based on whole blood samples from RA patients with cold-dampness syndrome and co-immunoprecipitation were performed to identify involved dominant pathways, which were experimentally verified using AIA-wind-cold-dampness stimulation modified (AIA-M) animal model.

RESULTS

TZG treatment dramatically attenuated joint injury and inflammatory response in AIA rats, and PSMC2-RUNX2-COL1A1 axis, which was closely associated with bone/cartilage damage, was inferred to be one of therapeutic targets of TZG against RA. Experimentally, TZG displayed obvious pharmacological effects for alleviating the joint inflammation and destruction through reinstating the body weight, reducing the arthritis score, the limbs diameters, the levels of RF and CRP, and the inflammatory cytokines, recovering the thymus and spleen indexes, diminishing bone and cartilage destruction, as well elevating the pain thresholds of AIA-M rats. In addition, TZG markedly reversed the abnormal energy metabolism in AIA-M rats through enhancing articular temperature, daily water consumption, and regulating expression levels of energy metabolism parameters and hormones. Moreover, TZG also significantly modulated the abnormal expression levels of PSMC2, RUNX2 and COL1A1 proteins in the ankle tissues of AIA-M rats.

CONCLUSION

TZG may exert the bone protective effects in RA therapy via regulating bone and cartilage damage-associated PSMC2-RUNX2-COL1A1 axis.

PSMC2 promotes the progression of gastric cancer via induction of RPS15A/mTOR pathway

As one of the most common malignant tumors, it is particularly important to further understand the development mechanism of gastric cancer and to find more effective therapeutic target genes. The results of immunohistochemical staining showed that PSMC2 was upregulated in gastric cancer. Cell function experiments indicated that PSMC2 knockdown inhibited the proliferation, clone formation and migration of gastric cancer cells, and induced apoptosis. In vivo experiments further showed that PSMC2 knockdown suppressed tumor growth. RPS15A and mTOR pathway were identified the downstream gene and pathway of PSMC2 by GeneChip and IPA. PSMC2 knockdown inhibited RPS15A expression and mTOR pathway, which was neutralized by RPS15A overexpression. Overexpression of RPS15A promoted the proliferation and migration of gastric cancer cells, which alleviated the inhibitory effect caused by PSMC2 knockdown to a certain extent. The mTOR pathway inhibitor Torin1 partially restored the promoting role of RPS15A overexpression on the gastric cancer cell proliferation. Furthermore, bioinformatics analysis and dual-luciferase reporter assays showed that PSMC2 and RPS15A competitively bound to hsa-let-7c-3p. Inhibition of hsa-let-7c-3p promoted the migration of MGC-803 cells and reduced the apoptosis level, while simultaneous inhibition PSMC2 and hsa-let-7c-3p restored the migration and apoptosis levels of gastric cancer cells. In conclusion, PSMC2 and RPS15A were highly expressed in gastric cancer. PSMC2 enhanced RPS15A levels by targeting hsa-let-7c-3p, and then activated mTOR pathway, thereby promoting the progression of gastric cancer.