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Talin1 phosphorylation activates ?1 integrins: a novel mechanism to promote prostate cancer bone metastasis.

ABSTRACT: Talins are adaptor proteins that regulate focal adhesion signaling by conjugating integrins to the cytoskeleton. Talins directly bind integrins and are essential for integrin activation. We previously showed that ?1 integrins are activated in metastatic prostate cancer (PCa) cells, increasing PCa metastasis to lymph nodes and bone. However, how ?1 integrins are activated in PCa cells is unknown. In this study, we identified a novel mechanism of ?1 integrin activation. Using knockdown experiments, we first demonstrated that talin1, but not talin2, is important in ?1 integrin activation. We next showed that talin1 S425 phosphorylation, but not total talin1 expression, correlates with metastatic potential of PCa cells. Expressing a non-phosphorylatable mutant, talin1(S425A), in talin1-silenced PC3-MM2 and C4-2B4 PCa cells, decreased activation of ?1 integrins, integrin-mediated adhesion, motility and increased the sensitivity of the cells to anoikis. In contrast, reexpression of the phosphorylation-mimicking mutant talin1(S425D) led to increased ?1 integrin activation and generated biologic effects opposite to talin1(S425A) expression. In the highly metastatic PC3-MM2 cells, expression of a non-phosphorylatable mutant, talin1(S425A), in talin1-silenced PC3-MM2 cells, abolished their ability to colonize in the bone following intracardiac injection, while reexpression of phosphorylation-mimicking mutant talin1(S425D) restored their ability to metastasize to bone. Immunohistochemical staining demonstrated that talin S425 phosphorylation is significantly increased in human bone metastases when compared with normal tissues, primary tumors or lymph node metastases. We further showed that p35 expression, an activator of Cdk5, and Cdk5 activity were increased in metastatic tumor cells, and that Cdk5 kinase activity is responsible for talin1 phosphorylation and subsequent ?1 integrin activation. Together, our study reveals Cdk5-mediated phosphorylation of talin1 leading to ?1 integrin activation is a novel mechanism that increases metastatic potential of PCa cells.

SUBMITTER: Jin JK

PROVIDER: S-EPMC4221586 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Talin1 phosphorylation activates β1 integrins: a novel mechanism to promote prostate cancer bone metastasis.

Jin J-K JK Tien P-C PC Cheng C-J CJ Song J H JH Huang C C Lin S-H SH Gallick G E GE

Oncogene 20140505 14

Talins are adaptor proteins that regulate focal adhesion signaling by conjugating integrins to the cytoskeleton. Talins directly bind integrins and are essential for integrin activation. We previously showed that β1 integrins are activated in metastatic prostate cancer (PCa) cells, increasing PCa metastasis to lymph nodes and bone. However, how β1 integrins are activated in PCa cells is unknown. In this study, we identified a novel mechanism of β1 integrin activation. Using knockdown experiments ...[more]

PMID: 24793790

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Project description:BackgroundBone metastasis is the leading cause of death in patients with prostate cancer (PCa) and currently has no effective treatment. Disseminated tumor cells in bone marrow often obtain new characteristics to cause therapy resistance and tumor recurrence. Thus, understanding the status of disseminated prostate cancer cells in bone marrow is crucial for developing a new treatment.MethodsWe analyzed the transcriptome of disseminated tumor cells from a single cell RNA-sequencing data of PCa bone metastases. We built a bone metastasis model through caudal artery injection of tumor cells, and sorted the tumor hybrid cells by flow cytometry. We performed multi-omics analysis, including transcriptomic, proteomic and phosphoproteomic analysis, to compare the difference between the tumor hybrid cells and parental cells. In vivo experiments were performed to analyze the tumor growth rate, metastatic and tumorigenic potential, drug and radiation sensitivity in hybrid cells. Single cell RNA-sequencing and CyTOF were performed to analyze the impact of hybrid cells on tumor microenvironment.ResultsHere, we identified a unique cluster of cancer cells in PCa bone metastases, which expressed myeloid cell markers and showed a significant change in pathways related to immune regulation and tumor progression. We found that cell fusion between disseminated tumor cells and bone marrow cells can be source of these myeloid-like tumor cells. Multi-omics showed the pathways related to cell adhesion and proliferation, such as focal adhesion, tight junction, DNA replication, and cell cycle, were most significantly changed in these hybrid cells. In vivo experiment showed hybrid cells had a significantly increased proliferative rate, and metastatic potential. Single cell RNA-sequencing and CyTOF showed tumor-associated neutrophils/monocytes/macrophages were highly enriched in hybrid cells-induced tumor microenvironment with a higher immunosuppressive capacity. Otherwise, the hybrid cells showed an enhanced EMT phenotype with higher tumorigenicity, and were resistant to docetaxel and ferroptosis, but sensitive to radiotherapy.ConclusionTaken together, our data demonstrate that spontaneous cell fusion in bone marrow can generate myeloid-like tumor hybrid cells that promote the progression of bone metastasis, and these unique population of disseminated tumor cells can provide a potential therapeutic target for PCa bone metastasis.

Project description:Background:The expression and mechanism of microRNA-205 (miRNA-205) in prostate cancer (PCa) and its bone metastasis remain controversial. Materials and Methods:The expression and discriminating capability of miRNA-205 were assessed by drawing a forest plot and a summarized receiver operating characteristic (SROC) curve, using data available from 27 miRNA-array and miRNA-sequencing datasets. The miRNA-205 target genes were acquired from online prediction tools, differentially upregulated genes in PCa, and differentially expressed genes (DEGs) after miRNA-205 transfection into PCa cell lines. Functional enrichment analysis was conducted to explore the biological mechanism of miRNA-205 targets. Immunohistochemistry (IHC) was applied to verify the protein level of the hub gene. Results:The expression of miRNA-205 in the PCa group (1,461 samples) was significantly lower than that in the noncancer group (510 samples), and the downregulation of miRNA-205 showed excellent sensitivity and specificity in differentiating between the two groups. In bone metastatic PCa, the miRNA-205 level was further reduced than in nonbone metastatic PCa, and it showed a good capability in distinguishing between the two groups. In total, 153 miRNA-205 targets were screened through the three aforementioned methods. Based on the results of functional enrichment analysis, the targets of miRNA-205 were mainly enriched during chromosome segregation and phospholipid-translocating ATPase activity and in the spindle microtubule and the p53 signaling pathway. CDK1 had the highest connectivity in the PPI network analysis and was screened as one of the hub genes. A statistically significant negative correlation between miRNA-205 and CDK1 was observed. The expression of CDK1 in PCa samples was pronouncedly upregulated in terms of both the mRNA level and the protein level when compared with noncancer samples. Conclusion:miRNA-205 may play a vital role in PCa tumorigenesis and bone metastasis by targeting CDK1.

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Talin1 phosphorylation activates ?1 integrins: a novel mechanism to promote prostate cancer bone metastasis.

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Talin1 phosphorylation activates β1 integrins: a novel mechanism to promote prostate cancer bone metastasis.

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