calpain and Prostatic-Neoplasms--Castration-Resistant

Metastasis is the major cause of cancer-specific death in patients with prostate cancer (PCa). We previously reported that collapsing response mediator protein-4 (CRMP4) is a PCa metastasis-suppressor gene and the hypermethylation in CRMP4 promoter is responsible for the transcription repression in metastatic PCa. However, the underlying mechanisms remain unknown. In this study, we aimed to investigate the role of calpain-2 in CRMP4 promoter hypermethylation and its functional modulation in PCa metastasis.. Calpain-2 expression in PCa tissues (n = 87) and its specific mechanisms of functional modulation in CRMP4 expression via limited enzymatic cleavage was investigated. We then focused on the cooperative crosstalk of calpain-2 and NF-κB RelA/p65 in CRMP4 promoter methylation for the initiation of PCa metastasis. Statistical differences between groups were determined using a two-tailed Student's t-test. P < 0.05 indicated statistically significant.. Calpain-2 was differentially upregulated in metastatic PCa compared with localized PCa. Moreover, calpain-2 cleaved CRMP4 into the N-terminally fragment which promoted migration and invasion in PCa cells via nuclear translocation and activation of E2F1-mediated DNA methyltransferase 1 (DNMT1) expression. NF-κB RelA/p65 recruited DNMT1 to bind to and methylate CRMP4 promoter in which Serine276 phosphorylation of p65 was essential. Furthermore, CRMP4 exhibited anti-metastatic function via inhibiting the expression of VEGFC through Semaphorin3B-Neuropilin2 signaling.. Calpain-2 may contribute to the promoter methylation of CRMP4 to repress its transcription, leading to the metastasis of PCa via enhancing VEGFC expression.

Topics: Aged; Calpain; Cell Line, Tumor; CpG Islands; DNA (Cytosine-5-)-Methyltransferase 1; DNA Methylation; Gene Expression Regulation, Neoplastic; Genes, Tumor Suppressor; Humans; Male; Membrane Glycoproteins; Middle Aged; Muscle Proteins; Neoplasm Metastasis; Neuropilin-2; Phosphorylation; Promoter Regions, Genetic; Prostatic Hyperplasia; Prostatic Neoplasms; Prostatic Neoplasms, Castration-Resistant; Receptor Cross-Talk; Retrospective Studies; Semaphorins; Signal Transduction; Transcription Factor RelA; Up-Regulation; Vascular Endothelial Growth Factor C

Docetaxel-based chemotherapy has been widely used as the first-line treatment for castration-resistant prostate cancer (CRPC) patients. However, the mechanisms of docetaxel-resistance remain unclear. In the present study with the establishment of 2 in vitro models of docetaxel-resistant CRPC cell sublines, we firstly reported that activation of calpain may play a promotional role in the resistance of docetaxel in prostate cancer, meanwhile using the calpain inhibitor combined with docetaxel improved the efficiency of docetaxel in docetaxel-resistant cell sublines. Moreover, we also found that the expression of androgen-independent constitutively and transcriptionally active androgen receptor splice variant-7 (AR-V7) remained high in the docetaxel-resistant CRPC cell subline Rv1-DR, and that it may be involved in acquired docetaxel-resistance of CRPC. However, a novel importin-β inhibitor (importazole) was only capable of slightly decreasing the transcriptional activity of the AR signaling pathway via blocking nuclear import of AR-FL and various non-specific AR-Vs, instead of AR-V7. These findings suggest that calpain and AR-V7 may serve as important biomarkers in the treatment of CRPC, and targeting calpain and AR-V7 may provide a new approach in overcoming docetaxel-resistance.

Topics: Androgens; Calpain; Cell Line, Tumor; Docetaxel; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Male; Prostatic Neoplasms, Castration-Resistant; Protein Isoforms; Quinazolines; Receptors, Androgen; Signal Transduction; Taxoids

The mRNA expression of CAPN2 was upregulated in CRPC cells (DU145 and PC3) than that in non-CRPC cells. Silencing CAPN2 expression could inhibit DU145 and PC3 cells proliferation by cell cycle arrest at G1 phase. Knockdown of CPAN2 level suppressed the migration and invasion capacity of CRPC cells by reducing matrix metalloproteinase-2 (MMP-2) and MMP-9 activation, as well as repressing the phosphorylation protein expression of AKT and mTOR. In addition, we found that the expression of CAPN2 was elevated in Pca tissues than that in normal control tissues. Therefore, we showed the important roles of CAPN2 in the development and progression in CRPC cells, suggesting a new therapeutic intervention for treating castration-resistant prostate cancer patients.

Topics: Aged; Calpain; Cell Movement; Cell Proliferation; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Gene Silencing; Humans; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Middle Aged; Neoplasm Invasiveness; Prostatic Neoplasms, Castration-Resistant; Proto-Oncogene Proteins c-akt; Real-Time Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; TOR Serine-Threonine Kinases; Wound Healing

It is now clear that progression from localized prostate cancer to incurable castrate-resistant prostate cancer (CRPC) is driven by continued androgen receptor (AR), signaling independently of androgen. Thus, there remains a strong rationale to suppress AR activity as the single most important therapeutic goal in CRPC treatment. Although the expression of ligand-independent AR splice variants confers resistance to AR-targeted therapy and progression to lethal castrate-resistant cancer, the molecular regulators of AR activity in CRPC remain unclear, in particular those pathways that potentiate the function of mutant AR in CRPC. Here, we identify FHL2 as a novel coactivator of ligand-independent AR variants that are important in CRPC. We show that the nuclear localization of FHL2 and coactivation of the AR is driven by calpain cleavage of the cytoskeletal protein filamin, a pathway that shows differential activation in prostate epithelial versus prostate cancer cell lines. We further identify a novel FHL2-AR-filamin transcription complex, revealing how deregulation of this axis promotes the constitutive, ligand-independent activation of AR variants, which are present in CRPC. Critically, the calpain-cleaved filamin fragment and FHL2 are present in the nucleus only in CRPC and not benign prostate tissue or localized prostate cancer. Thus, our work provides mechanistic insight into the enhanced AR activation, most notably of the recently identified AR variants, including AR-V7 that drives CRPC progression. Furthermore, our results identify the first disease-specific mechanism for deregulation of FHL2 nuclear localization during cancer progression. These results offer general import beyond prostate cancer, given that nuclear FHL2 is characteristic of other human cancers where oncogenic transcription factors that drive disease are activated like the AR in prostate cancer.

Topics: Animals; Calpain; Cell Line, Tumor; Cell Nucleus; Chlorocebus aethiops; COS Cells; Epithelial Cells; Filamins; Humans; Ligands; LIM-Homeodomain Proteins; Male; Muscle Proteins; Prostatic Neoplasms, Castration-Resistant; Receptors, Androgen; Transcription Factors; Transcriptional Activation