METHODS: Immunoblotting, immunofluorescence, quantitative real-time PCR and flow cytometry assays investigated the expression of E-cadherin and CXCR3 isoforms. Intrasplenic inoculation of human prostate cancer (PCa) cells with spontaneous metastasis to the liver analyzed E-cadherin and CXCR3-B expression during cancer progression in vivo.
RESULTS: We found reciprocal regulation of E-cadherin and CXCR3 isoforms. E-cadherin surface expression promoted CXCR3-B presentation on the cell membrane, and to a lesser extent increased its mRNA and total protein levels. In turn, forced expression of CXCR3-A reduced E-cadherin expression level, whereas CXCR3-B increased E-cadherin in PCa. Meanwhile, a positive correlation of E-cadherin and CXCR3-B expression was found both in experimental PCa liver micro-metastases and patients' tissue.
CONCLUSIONS: CXCR3-B and E-cadherin positively correlated in vitro and in vivo in PCa cells and liver metastases, whereas CXCR3-A negatively regulated E-cadherin expression. These results suggest that CXCR3 isoforms may play important roles in cancer progression and dissemination via diametrically regulating tumor's phenotype.
METHODS: In this study, a dystrophin-deficient myoblast cell line established from the skeletal muscle of a dystrophic (mdx) mouse was used as a model. The dfd13 (dystrophin-deficient) and C2C12 (non-dystrophic) myoblasts were cultured in low mitogen conditions for 10 days to induce differentiation. The cells were subjected to total protein extraction prior to Western blotting assay technique. Protein sub-fractionation has been conducted to determine protein localization. The live-cell analysis of autophagy assay was done using a flow cytometer.
RESULTS: In our culture system, the dfd13 myoblasts did not achieve terminal differentiation. PTEN expression was profoundly increased in dfd13 myoblasts throughout the differentiation day subsequently indicates perturbation of PI3K/Akt/mTOR regulation. In addition, rictor-mTORC2 was also found inactivated in this event. This occurrence has caused FoxO3 misregulation leads to higher activation of autophagy-related genes in dfd13 myoblasts. Autophagosome formation was increased as LC3B-I/II showed accumulation upon differentiation. However, the ratio of LC3B lipidation and autophagic flux were shown decreased which exhibited dystrophic features.
CONCLUSION: Perturbation of the PTEN-PI3K/Akt pathway triggers excessive autophagosome formation and subsequently reduced autophagic flux within dystrophin-deficient myoblasts where these findings are of importance to understand Duchenne Muscular Dystrophy (DMD) patients. We believe that some manipulation within its regulatory signaling reported in this study could help restore muscle homeostasis and attenuate disease progression. Video Abstract.
METHODS: We integrated genetic knockout (KO) of golgin-97, animal models (zebrafish and xenograft mice), multi-omics analysis (next-generation sequencing and proteomics), bioinformatics analysis, and kinase inhibitor treatment to evaluate the effects of golgin-97 KO in triple-negative breast cancer cells. Gene knockdown and kinase inhibitor treatment followed by qRT‒PCR, Western blotting, cell viability, migration, and cytotoxicity assays were performed to elucidate the mechanisms of golgin-97 KO-mediated cancer invasion. A xenograft mouse model was used to investigate cancer progression and drug therapy.
RESULTS: We demonstrated that golgin-97 KO promoted breast cell metastasis in zebrafish and xenograft mouse models. Multi-omics analysis revealed that the Wnt signaling pathway, MAPK kinase cascades, and inflammatory cytokines are involved in golgin-97 KO-induced breast cancer progression. Targeting the ERK1/2 and p38 MAPK pathways effectively attenuated golgin-97-induced cancer cell migration, reduced the expression of inflammatory mediators, and enhanced the chemotherapeutic effect of paclitaxel in vitro and in vivo. Specifically, compared with the paclitaxel regimen, the combination of ERK1/2 and p38 MAPK inhibitors significantly prevented lung metastasis and lung injury. We further demonstrated that hypoxia is a physiological condition that reduces golgin-97 expression in cancer, revealing a novel and potential feedback loop between ERK/MAPK signaling and golgin-97.
CONCLUSION: Our results collectively support a novel regulatory role of golgin-97 in ERK/MAPK signaling and the tumor microenvironment, possibly providing new insights for anti-breast cancer drug development.