LIMK2-NKX3.1 Engagement Promotes Castration-Resistant Prostate Cancer

Decoding the tumour-modulatory roles of LIMK2

LIM domains kinase 2 (LIMK2) is a 72 kDa protein that regulates actin and cytoskeleton reorganization. Once phosphorylated by its upstream activator (ROCK1), LIMK2 can phosphorylate cofilin to inactivate it. This relieves the levering stress on actin and allows polymerization to occur. Actin rearrangement is essential in regulating cell cycle progression, apoptosis, and migration. Dysregulation of the ROCK1/LIMK2/cofilin pathway has been reported to link to the development of various solid cancers such as breast, lung, and prostate cancer and liquid cancer like leukemia. This review aims to assess the findings from multiple reported in vitro, in vivo, and clinical studies on the potential tumour-regulatory role of LIMK2 in different human cancers. The findings of the selected literature unraveled that activated AKT, EGF, and TGF-β pathways can upregulate the activities of the ROCK1/LIMK2/cofilin pathway. Besides cofilin, LIMK2 can modulate the cellular levels of other proteins, such as TPPP1, to promote microtubule polymerization. The tumour suppressor protein p53 can transactivate LIMK2b, a splice variant of LIMK2, to induce cell cycle arrest and allow DNA repair to occur before the cell enters the next phase of the cell cycle. Additionally, several non-coding RNAs, such as miR-135a and miR-939-5p, could also epigenetically regulate the expression of LIMK2. Since the expression of LIMK2 is dysregulated in several human cancers, measuring the tissue expression of LIMK2 could potentially help diagnose cancer and predict patient prognosis. As LIMK2 could play tumour-promoting and tumour-inhibiting roles in cancer development, more investigation should be conducted to carefully evaluate whether introducing a LIMK2 inhibitor in cancer patients could slow cancer progression without posing clinical harms.

Molecular landscape for risk prediction and personalized therapeutics of castration-resistant prostate cancer: at a glance

Prostate cancer (PCa) is commonly occurred with high incidence in men worldwide, and many patients will be eventually suffered from the dilemma of castration-resistance with the time of disease progression. Castration-resistant PCa (CRPC) is an advanced subtype of PCa with heterogeneous carcinogenesis, resulting in poor prognosis and difficulties in therapy. Currently, disorders in androgen receptor (AR)-related signaling are widely acknowledged as the leading cause of CRPC development, and some non-AR-based strategies are also proposed for CRPC clinical analyses. The initiation of CRPC is a consequence of abnormal interaction and regulation among molecules and pathways at multi-biological levels. In this study, CRPC-associated genes, RNAs, proteins, and metabolites were manually collected and integrated by a comprehensive literature review, and they were functionally classified and compared based on the role during CRPC evolution, i.e., drivers, suppressors, and biomarkers, etc. Finally, translational perspectives for data-driven and artificial intelligence-powered CRPC systems biology analysis were discussed to highlight the significance of novel molecule-based approaches for CRPC precision medicine and holistic healthcare.

Enzalutamide combination with Arsenic trioxide suppresses the progression of castration-resistant prostate cancer

The study aimed to investigate the anti-tumor effects and underlying mechanisms of Enzalutamide (ENZ) and Arsenic trioxide (ATO) co-treatment on castration-resistant prostate cancer (CRPC). The effects on C4-2B cells were initially evaluated by colony formation assay, FACS analysis, and DNA fragmentation detection. Bioinformatics methods including mRNA-sequencing and gene enrichment analysis were used to screen the underlying target genes and pathways related to their actions. Western blot was employed to assess the expression levels of protein-related angiogenesis, apoptosis, DNA repair, and the screened genes. Finally, the effects were further verified in subcutaneous tumor models and tissue sections from the xenografts. It was found that not only could ENZ combination with ATO significantly inhibit cell proliferation and angiogenesis, but also induce cell arrest and apoptosis in C4-2B cells. In addition, interruption of the DNA damage repair-related pathways also occurred as a result of their combined effects. Western blot analysis further suggested that proteins involved in these pathways, especially P-ATR and P-CHEK1 were significantly reduced. In addition, their combination also inhibited the tumor growth of xenografts. Altogether, ENZ combination with ATO synergistically improved the therapeutic effects and suppressed CRPC progression through regulation of the ATR-CHEK1-CDC25C pathway.

Emerging proteins involved in castration‑resistant prostate cancer via the AR‑dependent and AR‑independent pathways (Review)

Despite achieving optimal initial responses to androgen deprivation therapy, most patients with prostate cancer eventually progress to a poor prognosis state known as castration‑resistant prostate cancer (CRPC). Currently, there is a notable absence of reliable early warning biomarkers and effective treatment strategies for these patients. Although androgen receptor (AR)‑independent pathways have been discovered and acknowledged in recent years, the AR signaling pathway continues to play a pivotal role in the progression of CRPC. The present review focuses on newly identified proteins within human CRPC tissues. These proteins encompass both those involved in AR‑dependent and AR‑independent pathways. Specifically, the present review provides an in‑depth summary and analysis of the emerging proteins within AR bypass pathways. Furthermore, the significance of these proteins as potential biomarkers and therapeutic targets for treating CRPC is discussed. Therefore, the present review offers valuable theoretical insights and clinical perspectives to comprehensively enhance the understanding of CRPC.

PDZ and LIM Domain-Encoding Genes: Their Role in Cancer Development

PDZ-LIM family proteins (PDLIMs) are a kind of scaffolding proteins that contain PDZ and LIM interaction domains. As protein-protein interacting molecules, PDZ and LIM domains function as scaffolds to bind to a variety of proteins. The PDLIMs are composed of evolutionarily conserved proteins found throughout different species. They can participate in cell signal transduction by mediating the interaction of signal molecules. They are involved in many important physiological processes, such as cell differentiation, proliferation, migration, and the maintenance of cellular structural integrity. Studies have shown that dysregulation of the PDLIMs leads to tumor formation and development. In this paper, we review and integrate the current knowledge on PDLIMs. The structure and function of the PDZ and LIM structural domains and the role of the PDLIMs in tumor development are described.

Enhancing Disease Risk Gene Discovery by Integrating Transcription Factor-Linked Trans-located Variants into Transcriptome-Wide Association Analyses

Transcriptome-wide association studies (TWAS) have been successful in identifying putative disease susceptibility genes by integrating gene expression predictions with genome-wide association studies (GWAS) data. However, current TWAS models only consider cis-located variants to predict gene expression. Here, we introduce transTF-TWAS, which includes transcription factor (TF)-linked trans-located variants for model building. Using data from the Genotype-Tissue Expression project, we predict alternative splicing and gene expression and applied these models to large GWAS datasets for breast, prostate, and lung cancers. Our analysis revealed 887 putative cancer susceptibility genes, including 465 in regions not yet reported by previous GWAS and 137 in known GWAS loci but not yet reported previously, at Bonferroni-corrected P < 0.05. We demonstrate that transTF-TWAS surpasses other approaches in both building gene prediction models and identifying disease-associated genes. These results have shed new light on several genetically driven key regulators and their associated regulatory networks underlying disease susceptibility.

Fibroblast-derived exosomal microRNA regulates NKX3-1 expression in androgen-sensitive, androgen receptor-dependent prostate cancer cells

Androgen deprivation therapy (ADT) targeting androgen production and androgen receptor (AR) signaling is the primary antihormonal therapy in the treatment of advanced prostate cancer (PCa). However, no clinically established molecular biomarkers have been identified to predict the effectiveness of ADT before starting ADT. The tumor microenvironment of PCa contains fibroblasts that regulate PCa progression by producing multiple soluble factors. We have previously reported that AR-activating factor-secreted fibroblasts increase the responsiveness of androgen-sensitive, AR-dependent PCa cells to ADT. Thus, we hypothesized that fibroblast-derived soluble factors may affect cancer cell differentiation by regulating cancer-related gene expression in PCa cells and that the biochemical characteristics of fibroblasts may be used to predict the effectiveness of ADT. Here, we investigated the effects of normal fibroblasts (PrSC cells) and three PCa patient-derived fibroblast lines (pcPrF-M5, -M28, and -M31 cells) on the expression of cancer-related genes in androgen-sensitive, AR-dependent human PCa cells (LNCaP cells) and three sublines showing different androgen sensitivities and AR dependencies. The mRNA expression of the tumor suppressor gene NKX3-1 in LNCaP cells and E9 cells (which show low androgen sensitivity and AR dependency) was significantly increased by treatment with conditioned media from PrSC and pcPrF-M5 cells but not from pcPrF-M28 and pcPrF-M31 cells. Notably, no upregulation of NKX3-1 was observed in F10 cells (AR-V7-expressing, AR-independent cells with low androgen sensitivity) and AIDL cells (androgen-insensitive, AR-independent cells). Among 81 common fibroblast-derived exosomal microRNAs that showed 0.5-fold lower expression in pcPrF-M28 and pcPrF-M31 cells than in PrSC and pcPrF-M5 cells, miR-449c-3p and miR-3121-3p were found to target NKX3-1. In only LNCaP cells, the NKX3-1 mRNA expression was significantly increased by transfection of an miR-3121-3p mimic but not that of the miR-449c-3p mimic. Thus, fibroblast-derived exosomal miR-3121-3p may be involved in preventing the oncogenic dedifferentiation of PCa cells by targeting NKX3-1 in androgen-sensitive, AR-dependent PCa cells.

The identification of a two-gene prognostic model based on cisplatin resistance-related ceRNA network in small cell lung cancer

BACKGROUND

Small cell lung cancer (SCLC) is a very malignant tumor with rapid growth and early metastasis. Platinum-based chemo-resistance is the major issue for SCLC treatment failure. Identifying a new prognostic model will help to make an accurate treatment decision for SCLC patients.

METHODS

Using the genomics of drug sensitivity in cancer (GDSC) database, we identified cisplatin resistance-related lncRNAs in SCLC cells. Based on the competing endogenous RNA (ceRNA) network, we identified the mRNAs correlated with the lncRNAs. Using Cox and LASSO regression analysis, a prognostic model was established. The survival prediction accuracy was evaluated by receiver operating characteristic (ROC) curve and Kaplan-Meier analysis. GSEA, GO, KEGG and CIBERSORT tools were used for functional enrichment and immune cells infiltration analysis.

RESULTS

We first screened out 10 differentially expressed lncRNAs between cisplatin resistant and sensitive SCLC cells from GDSC database. Based on ceRNA network, 31 mRNAs were identified with a correlation with the 10 lncRNAs. Furthermore, two genes (LIMK2 and PI4K2B) were identified by Cox and LASSO regression analysis to construct a prognostic model. Kaplan-Meier analysis indicated that the high-risk group had a poor overall survival compared with the low-risk group. The predicted area under the ROC curve (AUC) was 0.853 in the training set, and the AUC was 0.671 in the validation set. In the meanwhile, the low expression of LIMK2 or the high expression of PI4K2B in SCLC tumors was also significantly associated with poor overall survival in both training and validation sets. Functional enrichment analysis showed that the low-risk group was enriched in the apoptosis pathway and high immune infiltration of T cells. Finally, an apoptosis-related gene Cathepsin D (CTSD) was identified to be up-regulated in the low-risk group, and its higher expression correlated with better overall survival in SCLC.

CONCLUSION

We established a prognostic model and potential biomarkers (LIMK2, PI4K2B and CTSD), which could help to improve the risk stratification of SCLC patients.

LIMK2: A Multifaceted kinase with pleiotropic roles in human physiology and pathologies

LIMK2, a serine-specific kinase, was discovered as an actin dynamics regulating kinase. Emerging studies have shown its pivotal role in numerous human malignancies and neurodevelopmental disorder. Inducible knockdown of LIMK2 fully reverses tumorigenesis, underscoring its potential as a clinical target. However, the molecular mechanisms leading to its upregulation and its deregulated activity in various diseases largely remain unknown. Similarly, LIMK2's peptide substrate specificity has not been analyzed. This is particularly important for LIMK2, a kinase almost three decades old, as only a handful of its substrates are known to date. As a result, most of LIMK2's physiological and pathological roles have been assigned to its regulation of actin dynamics via cofilin. This review focuses on LIMK2's unique catalytic mechanism, substrate specificity and its upstream regulators at transcriptional, post-transcriptional and post-translational stages. Moreover, emerging studies have unveiled a few tumor suppressors and oncogenes as LIMK2's direct substrates, which in turn have uncovered novel molecular mechanisms by which it plays pleiotropic roles in human physiology and pathologies independent of actin dynamics.

LIM Kinases, LIMK1 and LIMK2, Are Crucial Node Actors of the Cell Fate: Molecular to Pathological Features

LIM kinase 1 (LIMK1) and LIM kinase 2 (LIMK2) are serine/threonine and tyrosine kinases and the only two members of the LIM kinase family. They play a crucial role in the regulation of cytoskeleton dynamics by controlling actin filaments and microtubule turnover, especially through the phosphorylation of cofilin, an actin depolymerising factor. Thus, they are involved in many biological processes, such as cell cycle, cell migration, and neuronal differentiation. Consequently, they are also part of numerous pathological mechanisms, especially in cancer, where their involvement has been reported for a few years and has led to the development of a wide range of inhibitors. LIMK1 and LIMK2 are known to be part of the Rho family GTPase signal transduction pathways, but many more partners have been discovered over the decades, and both LIMKs are suspected to be part of an extended and various range of regulation pathways. In this review, we propose to consider the different molecular mechanisms involving LIM kinases and their associated signalling pathways, and to offer a better understanding of their variety of actions within the physiology and physiopathology of the cell.

Biomarkers for the Detection and Risk Stratification of Aggressive Prostate Cancer

Current strategies for the clinical management of prostate cancer are inadequate for a precise risk stratification between indolent and aggressive tumors. Recently developed tissue-based molecular biomarkers have refined the risk assessment of the disease. The characterization of tissue biopsy components and subsequent identification of relevant tissue-based molecular alterations have the potential to improve the clinical decision making and patient outcomes. However, tissue biopsies are invasive and spatially restricted due to tumor heterogeneity. Therefore, there is an urgent need for complementary diagnostic and prognostic options. Liquid biopsy approaches are minimally invasive with potential utility for the early detection, risk stratification, and monitoring of tumors. In this review, we focus on tissue and liquid biopsy biomarkers for early diagnosis and risk stratification of prostate cancer, including modifications on the genomic, epigenomic, transcriptomic, and proteomic levels. High-risk molecular alterations combined with orthogonal clinical parameters can improve the identification of aggressive tumors and increase patient survival.

LIMK2 Is a Novel Prognostic Biomarker and Correlates With Tumor Immune Cell Infiltration in Lung Squamous Cell Carcinoma

Previous research found that LIM domain kinase 2 (LIMK2) expression correlated with a poor prognosis in many cancers. However, its role in lung squamous cell carcinoma (LUSC) has not yet been clarified. Our study aimed to clarify the role of LIMK2 in LUSC prognosis prediction and explore the relationship between LIMK2 and immune infiltration in LUSC. In this study, we first analyzed the expression level and prognostic value of LIMK2 across cancers. Subsequently, we explored the association of LIMK2 expression with immune infiltrating cells and immune checkpoints. our study found that LIMK2 was highly expressed and positively associated with the overall survival of LUSC. Moreover, our study further indicated that LIMK2 expression was significantly negatively correlated with immune cell infiltration and immune checkpoints in LUSC. Finally, we confirmed upstream regulatory noncoding RNAs (ncRNAs) of LIMK2, and the PVT1 and DHRS4-AS1/miR-423-5p/LIMK2 regulatory axes were successfully constructed in LUSC. Put together, LIMK2 is a novel prognostic biomarker and correlates with tumor immune cell infiltration in LUSC, and the expression of LIMK2 is regulated by the PVT1 and DHRS4-AS1/miR-423-5p axes.

Reciprocal deregulation of NKX3.1 and AURKA axis in castration-resistant prostate cancer and NEPC models

Background

NKX3.1, a prostate-specific tumor suppressor, is either genomically lost or its protein levels are severely downregulated, which are invariably associated with poor prognosis in prostate cancer (PCa). Nevertheless, a clear disconnect exists between its mRNA and protein levels, indicating that its post-translational regulation may be critical in maintaining its protein levels. Similarly, AURKA is vastly overexpressed in all stages of prostate cancer (PCa), including castration-resistant PCa (CRPC) and neuroendocrine PCa (NEPC), although its transcripts are only increased in ~ 15% of cases, hinting at additional mechanisms of deregulation. Thus, identifying the upstream regulators that control AURKA and NKX3.1’s levels and/or their downstream effectors offer an alternative route to inhibit AURKA and upregulate NKX3.1 in highly fatal CRPC and NEPC. AURKA and NKX3.1 have not linked to each other in any study to date.

Methods

A chemical genetic screen revealed NKX3.1 as a direct target of AURKA. AURKA-NKX3.1 cross-talk was analyzed using several biochemical techniques in CRPC and NEPC cells.

Results

We uncovered a reciprocal loop between AURKA and NKX3.1 in CRPC and NEPC cells. We observed that AURKA-mediated NKX3.1 downregulation is a major mechanism that drives CRPC pathogenesis and NEPC differentiation. AURKA phosphorylates NKX3.1 at three sites, which degrades it, but AURKA does not regulate NKX3.1 mRNA levels. NKX3.1 degradation drives highly aggressive oncogenic phenotypes in cells. NKX3.1 also degrades AURKA in a feedback loop. NKX3.1-AURKA loop thus upregulates AKT, ARv7 and Androgen Receptor (AR)-signaling in tandem promoting highly malignant phenotypes. Just as importantly, we observed that NKX3.1 overexpression fully abolished synaptophysin and enolase expression in NEPC cells, uncovering a strong negative relationship between NKX3.1 and neuroendocrine phenotypes, which was further confirmed be measuring neurite outgrowth. While WT-NKX3.1 inhibited neuronal differentiation, 3A-NKX3.1 expression obliterated it.

Conclusions

NKX3.1 loss could be a major mechanism causing AURKA upregulation in CRPC and NEPC and vice versa. NKX3.1 genomic loss requires gene therapy, nonetheless, targeting AURKA provides a powerful tool to maintain NKX3.1 levels. Conversely, when NKX3.1 upregulation strategy using small molecules comes to fruition, AURKA inhibition should work synergistically due to the reciprocal loop in these highly aggressive incurable diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-021-00765-z.