Chemokine signaling regulates cell migration and tumor metastasis. CXCL12, a member of the chemokine family, and its receptor, CXCR4, a G protein coupled receptor (GPCR), are key mediators of prostate-cancer (PC) bone metastasis. In PC cells androgens activate CXCR4 gene expression and receptor signaling on lipid rafts, which induces protease expression and cancer cell invasion. To identify novel lipid-raft-associated CXCR4 regulators supporting invasion/metastasis, we performed a SILAC-based quantitative proteomic analysis of lipid-rafts derived from PC3 stable cell lines with overexpression or knockdown of CXCR4. This analysis identified the evolutionarily conserved phosphatidylinositol 4-kinase IIIα (PI4KIIIα), and SAC1 phosphatase that dephosphorylates phosphatidylinositol-4-phosphate as potential candidate CXCR4 regulators. CXCR4 interacted with PI4KIIIα membrane targeting machinery recruiting them to the plasma membrane for PI4P production. Consistent with this interaction, PI4KIIIα was found tightly linked to the CXCR4 induced PC cell invasion. Thus, ablation of PI4KIIIα in CXCR4-expressing PC3 cells reduced cellular invasion in response to a variety of chemokines. Immunofluorescence microscopy in CXCR4-expressing cells revealed localized production of PI4P on the invasive projections. Human tumor studies documented increased PI4KIIIα expression in metastatic tumors vs. the primary tumor counterparts, further supporting the PI4KIIIα role in tumor metastasis. Furthermore, we also identified an unexpected function of PI4KIIIα in GPCR signaling where CXCR4 regulates PI4KIIIα activity and mediate tumor metastasis. Altogether, our study identifies a novel cross-talk between PI4KIIIα and CXCR4 in promoting tumor metastasis and suggests that PI4KIIIα pharmacological targeting may have therapeutic benefit for advanced prostate cancer patients.

中文翻译：

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前列腺癌细胞中CXCR4与PI4KIIIα之间的新型串扰。

趋化因子信号传导调节细胞迁移和肿瘤转移。CXCL12是趋化因子家族的成员，其受体CXCR4是一种G蛋白偶联受体（GPCR），是前列腺癌（PC）骨转移的关键介质。在PC细胞中，雄激素激活脂筏上的CXCR4基因表达和受体信号传导，从而诱导蛋白酶表达和癌细胞入侵。为了鉴定支持侵袭/转移的新型脂类筏相关的CXCR4调节剂，我们对源自PC3稳定细胞系且CXCR4过表达或敲低的脂筏进行了基于SILAC的定量蛋白质组学分析。该分析确定了进化上保守的磷脂酰肌醇4-激酶IIIα（PI4KIIIα）和SAC1磷酸酶，该磷酸酯使磷脂酰肌醇-4-磷酸去磷酸化作为潜在的候选CXCR4调节剂。CXCR4与PI4KIIIα膜靶向设备相互作用，将它们募集到质膜上以生产PI4P。与此相互作用一致，发现PI4KIIIα与CXCR4诱导的PC细胞侵袭紧密相关。因此，消融表达CXCR4的PC3细胞中的PI4KIIIα可减少细胞对多种趋化因子的侵袭。在表达CXCR4的细胞中进行的免疫荧光显微镜检查显示，PI4P在侵袭性突起上局部产生。人类肿瘤研究表明，与原发性肿瘤相比，转移性肿瘤中PI4KIIIα表达增加，进一步支持了PI4KIIIα在肿瘤转移中的作用。此外，我们还确定了PI4KIIIα在GPCR信号转导中的意外功能，其中CXCR4调节PI4KIIIα活性并介导肿瘤转移。共，