Effect of PI3K/Akt Signaling Pathway on the Process of Prostate Cancer Metastasis to Bone

Exploring the interplay between the TGF-βpathway and SLN-mediated transfection: implications for gene delivery efficiency in prostate cancer and non-cancer cells

Solid lipid nanoparticles (SLN) are widely recognized for their biocompatibility, scalability, and long-term stability, making them versatile formulations for drug and gene delivery. Cellular interactions, governed by complex endocytic and signaling pathways, are pivotal for successfully applying SLN as a therapeutic agent. This study aims to enhance our understanding of the intricate interplay between SLN and cells by investigating the influence of specific endocytic and cell signaling pathways, with a focus on the impact of the TGF-βpathway on SLN-mediated cell transfection in both cancerous and non-cancerous prostate cells. Here, we systematically explored the intricate mechanisms governing the interactions between solid lipid nanoparticles and cells. By pharmacologically manipulating endocytic and signaling pathways, we analyzed alterations in SLNplex internalization, intracellular traffic, and cell transfection dynamics. Our findings highlight the significant role of macropinocytosis in the internalization and transfection processes of SLNplex in both cancer and non-cancer prostate cells. Moreover, we demonstrated that the TGF-βpathway is an important factor influencing endosomal release, potentially impacting gene expression and modulating cell transfection efficiency. This study provides novel insights into the dynamic mechanisms governing the interaction between cells and SLN, emphasizing the pivotal role of TGF-βsignaling in SLN-mediated transfection, affecting internalization, intracellular transport, and release of the genetic cargo. These findings provide valuable insight for the optimization of SLN-based therapeutic strategies in prostate-related applications.

Bone sialoprotein promotes lung cancer osteolytic bone metastasis via MMP14-dependent mechanisms

Bone metastases during lung cancer are common. Bone sialoprotein (BSP), a non-collagenous bone matrix protein, plays important functions in bone mineralization processes and in integrin-mediated cell-matrix interactions. Importantly, BSP induces bone metastasis in lung cancer, but the underlying mechanisms remain unclear. This study therefore sought to determine the intracellular signaling pathways responsible for BSP-induced migration and invasion of lung cancer cells to bone. Analyses of the Kaplan-Meier, TCGA, GEPIA and GENT2 databases revealed that high levels of BSP expression in lung tissue samples were associated with significantly decreased overall survival (hazard ratio = 1.17; p=0.014) and with a more advanced clinical disease stage (F-value = 2.38, p<0.05). We also observed that BSP-induced stimulation of matrix metalloproteinase (MMP)-14 promoted lung cancer cell migration and invasion via the PI3K/AKT/AP-1 signaling pathway. Notably, BSP promoted osteoclastogenesis in RAW 264.7 cells exposed to RANKL and BSP neutralizing antibody reduced osteoclast formation in conditioned medium (CM) from lung cancer cell lines. Finally, at 8 weeks after mice were injected with A549 cells or A549 BSP shRNA cells, the findings revealed that the knockdown of BSP expression significantly reduced metastasis to bone. These findings suggest that BSP signaling promotes lung bone metastasis via its direct downstream target gene MMP14, which reveals a novel potential therapeutic target for lung cancer bone metastases.

Arctiin Inhibits Cervical Cancer Cell Migration and Invasion through Suppression of S100A4 Expression via PI3K/Akt Pathway

Arctiin, a lignan glycoside, is isolated from Arctium lappa L. The anticancer effects of arctiin have been demonstrated in several studies. However, no research has been conducted on the anti-migration effect of arctiin in cervical cancer cells. The present study examined the effects of arctiin on cervical cancer cells and investigated the possible molecular mechanism. We demonstrated that arctiin exhibited low cytotoxicity and significantly inhibited cell migration and invasion in human cervical cancer cells. The S100A4 protein expression and mRNA levels were significantly reduced in HeLa and SiHa cells with arctiin treatment. Furthermore, silencing S100A4 by using small interfering RNA reduced cell migration, while overexpression of S100A4 mitigated the migration inhibition imposed by arctiin in cervical cancer cells. Western blotting revealed that arctiin significantly reduced phosphoinositide 3-kinase (PI3K) and phosphorylation of Akt in cervical cancer cells. Moreover, selective Akt induction by an Akt activator, SC-79, reverted cervical cancer cell migration and S100A4 protein expression, which were reduced in response to arctiin. Taken together, these results suggest that arctiin inhibits cervical cancer cell migration and invasion through suppression of S100A4 and the PI3K/Akt pathway.

Advancing Treatment of Bone Metastases through Novel Translational Approaches Targeting the Bone Microenvironment

Bone metastases represent a lethal condition that frequently occurs in solid tumors such as prostate, breast, lung, and renal cell carcinomas, and increase the risk of skeletal-related events (SREs) including pain, pathologic fractures, and spinal cord compression. This unique metastatic niche consists of a multicellular complex that cancer cells co-opt to engender bone remodeling, immune suppression, and stromal-mediated therapeutic resistance. This review comprehensively discusses clinical challenges of bone metastases, novel preclinical models of the bone and bone marrow microenviroment, and crucial signaling pathways active in bone homeostasis and metastatic niche. These studies establish the context to summarize the current state of investigational agents targeting BM, and approaches to improve BM-targeting therapies. Finally, we discuss opportunities to advance research in bone and bone marrow microenvironments by increasing complexity of humanized preclinical models and fostering interdisciplinary collaborations to translational research in this challenging metastatic niche.

Targeting Bone Metastases Signaling Pathway Using Moringa oleifera Seed Nutri-miRs: A Cross Kingdom Approach

Moringa oleifera is a medicinally important plant that has various medical and nutritional uses. Plant miRNAs are a class of non-coding endogenous small RNAs that regulate human-specific mRNA but the mechanistic actions are largely unknown. Here, in this study, we aim to explore the mechanistic action and influence of M. oleifera seed miRNAs on vital human target genes using computer based approaches. The M. oleifera seed miRNAs sequence was taken from published data and identified its human gene targets using a psRNA target analysis server. We identified 94 miRNAs that are able to significantly regulate 47 human target genes, which has enormous biological and functional importance. Out of 47 human targeted genes, 23 genes were found to be associated with PI3K-AKT, RUNX, and MAPK1/MAPK3 signaling pathway which has shown to play key roles in bone metastases during cancer progression. The M. oleifera seed miRNAs hold a strong potential for future research that might uncover the possibility of miRNA-facilitated cross-kingdom regulation and therapeutic targets for bone metastases.

Exosomes derived from PC-3 cells suppress osteoclast differentiation by downregulating miR-148a and blocking the PI3K/AKT/mTOR pathway

Prostate cancer is a leading malignancy in men that can also disrupt the bone tissue balance. Among all urological cancers, prostate cancer is associated with the highest rate of bone metastases, which can greatly reduce a patient's quality of life. In recent years, cell-derived exosomes, which can contain a wide range of biologically active molecules, have been reported as a novel method of communication among individual cells. However, the specific role that exosomes serve in this disease has not been fully elucidated. The prostate cancer cell line PC-3 were applied in the present study, where its exosomes were isolated to explore their potential effects on osteoclast differentiation. Exosomes are extracellular vesicles secreted by cells. The size of exosomes is 30-150 nm. They have double membrane structure and saucer-like morphology. They contain rich contents (including nucleic acid, protein and lipid) and participate in molecular transmission between cells. The combined results of tartrate-resistant acid phosphatase staining (to identify osteoclasts obtained from human peripheral blood mononuclear cells), reverse transcription-quantitative PCR and western blotting showed that PC-3-derived exosomes attenuated osteoclast differentiation by downregulating marker genes associated with osteoclastic maturation, including V-maf musculoaponeurotic fibrosarcoma oncogene homolog B, matrix metalloproteinase 9 and integrin β3. microRNA (miR)-148a expression was also found to be downregulated in osteoclasts by PC-3-derived exosomes. In addition, the mTOR and AKT signaling pathways were blocked after exposure to these PC-3 cell-derived exosomes. Therefore, results from the present study suggest that miR-148a mimics may be a new therapeutic approach for the prevention of prostate cancer bone metastases.

miR-7/EGFR/MEGF9 axis regulates cartilage degradation in osteoarthritis via PI3K/AKT/mTOR signaling pathway

Osteoarthritis (OA) is a common degenerative disease in middle-aged and elderly people. Our previous study has proved that microRNA-7 (miR-7) exacerbated the OA process. This study was aimed to explore the downstream genes and mechanism regulated by miR-7 to affect OA. Multiple EGF-like-domains 9 (MEGF9) was the predicted target of miR-7 by databases. Luciferase report experiment results confirmed that MEGF9 could bind to miR-7. Among the 10 collected pairs of OA and healthy samples, the expression levels of miR-7 and MEGF9 were both up-regulated when compared with healthy subjects by qRT-PCR and immunohistochemistry (IHC). The increased MEGF9 levels were due to the interaction with epidermal growth factor receptor (EGFR) by co-immunoprecipitation. Evaluations found that upregulation of miR-7 or MEGF9 can increase the expression of EGFR, matrix metalloproteinase-13 (MMP-13) and a disintegrin like and metallopeptidase with thrombospondin type 1 motif 5 (ADAMTS-5), so as to aggravate cartilage degradation. In addition, this effect induced by miR-7/EGFR/MEGF9 axis was by activation of PI3K/AKT signaling. The IHC and western blot assay results on OA model mice also demonstrated that miR-7/EGFR/MEGF9 axis regulated cartilage degradation in vivo. In summary, miR-7/EGFR/MEGF9 axis may perform a crucial function in the regulation of OA, providing potential for OA treatment.

SPLICE-q: a Python tool for genome-wide quantification of splicing efficiency

BACKGROUND

Introns are generally removed from primary transcripts to form mature RNA molecules in a post-transcriptional process called splicing. An efficient splicing of primary transcripts is an essential step in gene expression and its misregulation is related to numerous human diseases. Thus, to better understand the dynamics of this process and the perturbations that might be caused by aberrant transcript processing it is important to quantify splicing efficiency.

RESULTS

Here, we introduce SPLICE-q, a fast and user-friendly Python tool for genome-wide SPLICing Efficiency quantification. It supports studies focusing on the implications of splicing efficiency in transcript processing dynamics. SPLICE-q uses aligned reads from strand-specific RNA-seq to quantify splicing efficiency for each intron individually and allows the user to select different levels of restrictiveness concerning the introns' overlap with other genomic elements such as exons of other genes. We applied SPLICE-q to globally assess the dynamics of intron excision in yeast and human nascent RNA-seq. We also show its application using total RNA-seq from a patient-matched prostate cancer sample.

CONCLUSIONS

Our analyses illustrate that SPLICE-q is suitable to detect a progressive increase of splicing efficiency throughout a time course of nascent RNA-seq and it might be useful when it comes to understanding cancer progression beyond mere gene expression levels. SPLICE-q is available at: https://github.com/vrmelo/SPLICE-q.

AKT in Bone Metastasis of Solid Tumors: A Comprehensive Review

Simple Summary

Bone metastasis is a frequent complication of solid tumors and leads to a reduced overall survival. Although much progress has been made in the field of tumor therapy in the last years, bone metastasis depicts a stage of the disease with a lack of appropriate therapeutical options. Hence, this review aims to present the role of AKT in bone metastasis of solid tumors to place the spotlight on AKT as a possible therapeutical approach for patients with bone metastases. Furthermore, we intended to discuss postulated underlying molecular mechanisms of the bone metastasis-promoting effect of AKT, especially in highly bone-metastatic breast, prostate, and lung cancer. To conclude, this review identified the AKT kinase as a potential therapeutical target in bone metastasis and revealed remaining questions, which need to be addressed in further research projects.

Abstract

Solid tumors, such as breast cancer and prostate cancer, often form bone metastases in the course of the disease. Patients with bone metastases frequently develop complications, such as pathological fractures or hypercalcemia and exhibit a reduced life expectancy. Thus, it is of vital importance to improve the treatment of bone metastases. A possible approach is to target signaling pathways, such as the PI3K/AKT pathway, which is frequently dysregulated in solid tumors. Therefore, we sought to review the role of the serine/threonine kinase AKT in bone metastasis. In general, activation of AKT signaling was shown to be associated with the formation of bone metastases from solid tumors. More precisely, AKT gets activated in tumor cells by a plethora of bone-derived growth factors and cytokines. Subsequently, AKT promotes the bone-metastatic capacities of tumor cells through distinct signaling pathways and secretion of bone cell-stimulating factors. Within the crosstalk between tumor and bone cells, also known as the vicious cycle, the stimulation of osteoblasts and osteoclasts also causes activation of AKT in these cells. As a consequence, bone metastasis is reduced after experimental inhibition of AKT. In summary, AKT signaling could be a promising therapeutical approach for patients with bone metastases of solid tumors.

Distinct roles for the RNA-binding protein Staufen1 in prostate cancer

BACKGROUND

Prostate cancer is one of the most common malignant cancers with the second highest global rate of mortality in men. During the early stages of disease progression, tumour growth is local and androgen-dependent. Despite treatment, a large percentage of patients develop androgen-independent prostate cancer, which often results in metastases, a leading cause of mortality in these patients. Our previous work on the RNA-binding protein Staufen1 demonstrated its novel role in cancer biology, and in particular rhabdomyosarcoma tumorigenesis. To build upon this work, we have focused on the role of Staufen1 in other forms of cancer and describe here the novel and differential roles of Staufen1 in prostate cancer.

METHODS

Using a cell-based approach, three independent prostate cancer cell lines with different characteristics were used to evaluate the expression of Staufen1 in human prostate cancer relative to control prostate cells. The functional impact of Staufen1 on several key oncogenic features of prostate cancer cells including proliferation, apoptosis, migration and invasion were systematically investigated.

RESULTS

We show that Staufen1 levels are increased in all human prostate cancer cells examined in comparison to normal prostate epithelial cells. Furthermore, Staufen1 differentially regulates growth, migration, and invasion in the various prostate cancer cells assessed. In LNCaP prostate cancer cells, Staufen1 regulates cell proliferation through mTOR activation. Conversely, Staufen1 regulates migration and invasion of the highly invasive, bone metastatic-derived, PC3 prostate cells via the activation of focal adhesion kinase.

CONCLUSIONS

Collectively, these results show that Staufen1 has a direct impact in prostate cancer development and further demonstrate that its functions vary amongst the prostate cancer cell types. Accordingly, Staufen1 represents a novel target for the development of much-needed therapeutic strategies for prostate cancer.

MiRNA-145-5p expression and prospective molecular mechanisms in the metastasis of prostate cancer

The clinicopathological implication and prospective molecular mechanisms of miRNA-145-5p in the metastasis of prostate cancer (PCa) stand unclear. Herein, it is found that miRNA-145-5p expression was remarkably reduced in 131 cases of metastatic PCa than 1371 cases of localised ones, as the standardised mean differences (SMD) was -1.26 and the area under the curve (AUC) was 0.86, based on miRNA-chip and miRNA-sequencing datasets. The potential targets of miRNA-145-5p in metastatic PCa (n = 414) was achieved from the intersection of miRNA-145-5p transfected metastatic PCa cell line data, differential expression of metastatic PCa upregulated genes and online prediction databases. TOP2A was screened as one of the target hub genes by PPI network analysis, which was adversely related to miRNA-145-5p expression in both metastatic PCa (r = -0.504) and primary PCa (r = -0.281). Gene-chip and RNA-sequencing datasets, as well as IHC performed on clinical PCa samples, showed consistent upregulated expression of TOP2A mRNA and protein in PCa compared with non-PCa. The expression of TOP2A mRNA was also significantly higher in metastatic than localised PCa with the SMD being 1.72 and the AUC of sROC being 0.91. In summary, miRNA-145-5p may participate in PCa metastasis by binding TOP2A and be useful as a biomarker for the detection of metastatic PCa.

Circular RNA cir-ITCH Is a Potential Therapeutic Target for the Treatment of Castration-Resistant Prostate Cancer

cir-ITCH, a well-known tumor-suppressive circular RNA, plays a critical role in different cancers. However, its expression and functional role in prostate cancer (PCa) are unclear. Herein, we explored the potential mechanism and tumor-inhibiting role of cir-ITCH in PCa. Using reverse transcriptase polymerase chain reaction assay, we analyzed the expression of cir-ITCH in PCa and paired adjacent nontumor tissue samples resected during surgical operation, as well as in two cell lines of human PCa (LNCaP and PC-3) and the immortalized normal prostate epithelial cell line (RWPE-1). Cell viability and migration of PCa cell lines were evaluated using CCK-8 and wound-healing assays. Expression of key proteins of the Wnt/β-catenin and PI3K/AKT/mTOR pathways was detected using western blotting. We found that cir-ITCH expression was typically downregulated in the tissues and cell lines of PCa compared to that in the peritumoral tissue and in RWPE-1 cells, respectively. The results showed that cir-ITCH overexpression significantly inhibits the proliferation, migration, and invasion of human PCa cells and that reciprocal inhibition of expression occurred between cir-ITCH and miR-17. Proteins in the Wnt/β-catenin and PI3K/AKT/mTOR pathways were downregulated by overexpression of cir-ITCH both in androgen receptor-positive LNCaP cells and androgen receptor-negative PC-3 cells. Taken together, these data demonstrated that cir-ITCH plays a tumor-suppressive role in human PCa cells, partly through the Wnt/β-catenin and PI3K/AKT/mTOR pathways. Thus, cir-ITCH may serve as a novel therapeutic target for the treatment of PCa, especially castration-resistant prostate cancer.

Endogenous parathyroid hormone (PTH) signals through osteoblasts via RANKL during fracture healing to affect osteoclasts

AIM

To investigate the effect of endogenous PTH deficiency on osteoclasts during fracture healing and its mechanism.

METHODS

A femoral fracture model was used to determine the role of endogenous PTH in fracture healing. Immunohistochemistry, qPCR, and Western blot were used to determine the potential functions and mechanisms of endogenous PTH.

RESULT

In this study, we found that expression of RANKL and CK was lower in PTH knockout (KO) mice than in wild type (WT) mice. In vitro culture of osteoclasts showed that under the same stimulation, there was no statistical difference in the number of osteoclasts and the area of bone resorption areas in PTH WT mice and PTH KO mice. We found that a high concentration of RANKL could promote the number and activity of osteoclasts. Upon induction of osteoblasts in vitro, those from the PTH WT group expressed higher RANKL protein and mRNA than those from the PTH KO group. Lastly, we confirmed that the PI3K/AKT/STAT5 pathway promotes RANKL increase from osteoblasts.

CONCLUSION

During fracture healing, endogenous PTH deficiency can affect osteoclast activity by reducing RANKL expression in osteoblasts.

High-pressure artificial pneumothorax promotes invasion and metastasis of oesophageal cancer cells

OBJECTIVES

This study aimed to investigate the viability, apoptosis, invasion and metastasis of oesophageal cancer cells in a simulated artificial pneumothorax model and to explore its potential mechanism of action.

METHODS

Oesophageal cancer cells were subjected to a simulated thoracoscopic CO2 pneumothorax environment with different pressures and exposure times (low-pressure group: 8 mmHg 1 h or 8 mmHg 4 h; high-pressure group: 12 mmHg 1 h). Cell viability, apoptosis, invasive capacity and mRNA expression of adhesion- and metastasis-related molecules in each group were detected. To explore in greater detail the potential reasons for the changes in biological behaviour under the high-pressure CO2 environment, we designed 3 additional experimental groups: (i) high-pressure group, (ii) hypoxia group and (iii) pH decrease group. An miRNA microarray analysis was performed by comparing 2 paired samples of cells from the high-pressure group and the control group.

RESULTS

Treatment with high-pressure CO2 pneumothorax significantly increased the cell viability (P < 0.001) and the cell invasion (P < 0.001). Significantly higher expression of adhesive- and metastasis-related molecules was also observed. Further experiments indicated that the high-pressure CO2 pneumothorax might increase cell invasion and metastasis through the high pressure and decreased pH. The miRNA microarray analysis results suggested that several potential pathways related to cancer development: the RhoA pathway, the PI3K-Akt signalling pathway and the MAPK signalling pathway.

CONCLUSIONS

The application of high-pressure CO2 pneumothorax promoted the invasion and metastasis of oesophageal cancer cells through high pressure and decreased pH. This process might be related to several signalling pathways.

The PI3K inhibitor buparlisib suppresses osteoclast formation and tumour cell growth in bone metastasis of lung cancer, as evidenced by multimodality molecular imaging

Non‑small cell lung cancer (NSCLC) metastasis commonly occurs in bone, which often results in pathological fractures. Sustained phosphoinositide‑3‑kinase (PI3K) signalling promotes the growth of PI3K‑dependent NSCLC and elevates osteoclastogenic potential. The present study investigated the effects of a PI3K inhibitor on NSCLC growth in bone and osteoclast formation, and aimed to determine whether it could control symptoms associated with bone metastasis. A bone metastasis xenograft model was established by implanting NCI‑H460‑luc2 lung cancer cells, which contain a phosphatidylinositol‑​4,5‑bisphosphate 3‑kinase catalytic subunit α mutation, into the right tibiae of mice. After 1 week, the tumours were challenged with a PI3K inhibitor (buparlisib) or blank control for 3 weeks. Tumour growth and burden were longitudinally assessed in vivo via reporter gene bioluminescence imaging (BLI), small animal positron emission tomography/computed tomography (CT) [18F‑fluorodeoxyglucose (18F‑FDG)] and single‑photon emission computed tomography/CT [99mTc‑methylene diphosphonate (99mTc‑MDP)] imaging. Tibia sections of intraosseous NCI‑H460 tumours were analysed by immunohistochemistry (IHC), western blotting and flow cytometry. Dynamic weight bearing (DWB) tests were further performed to examine the improvement of symptoms associated with bone metastasis during the entire study. Administration of buparlisib significantly inhibited the progression of bone metastasis of NSCLC, as evidenced by significantly reduced uptake of 18F‑FDG, 99mTc‑MDP and BLI signals in the treated lesions. In addition, buparlisib appeared to inhibit the expression of tartrate‑resistant acid phosphatase and receptor activator of nuclear factor‑κB ligand, as determined by IHC. Buparlisib also resulted in increased cell apoptosis, as determined by a higher percentage of Annexin V staining and increased caspase 3 expression. Furthermore, buparlisib significantly increased weight‑bearing capacity, as revealed by DWB tests. The PI3K inhibitor, buparlisib, suppressed osteoclast formation in vivo, and exhibited antitumour activity, thus leading to increased weight‑bearing ability in mice with bone metastasis of lung cancer. Therefore, targeting the PI3K pathway may be a potential therapeutic strategy that prevents the structural skeletal damage associated with bone metastasis of lung cancer.

Identification of aberrantly methylated differentially expressed genes in prostate carcinoma using integrated bioinformatics

Background

Methylation plays a key role in the aetiology and pathogenesis of prostate cancer (PCa). This study aimed to identify aberrantly methylated differentially expressed genes (DEGs) and pathways in PCa and explore the underlying mechanisms of tumourigenesis.

Methods

Expression profile (GSE29079) and methylation profile (GSE76938) datasets were obtained from the Gene Expression Omnibus (GEO). We used R 3.4.4 software to assess aberrantly methylated DEGs. The Cancer Genome Atlas (TCGA) RNA sequencing and Illumina HumanMethylation450 DNA methylation data were utilized to validate screened genes. Functional enrichment analysis of the screened genes was performed, and a protein–protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Gens (STRING). The results were visualized in Cytoscape. After confirmation using TCGA, cBioPortal was used to examine alterations in genes of interest. Then, protein localization in PCa cells was observed using immunohistochemistry.

Results

Overall, 536 hypomethylated upregulated genes were identified that were enriched in biological processes such as negative regulation of transcription, osteoblast differentiation, intracellular signal transduction, and the Wnt signalling pathway. Pathway enrichment showed significant changes in factors involved in AMPK signalling, cancer, and adherens junction pathways. The hub oncogenes were AKT1, PRDM10, and FASN. Additionally, 322 hypermethylated downregulated genes were identified that demonstrated enrichment in biological processes including positive regulation of the MAPK cascade, muscle contraction, ageing, and signal transduction. Pathway analysis indicated enrichment in arrhythmogenic right ventricular cardiomyopathy (ARVC), focal adhesion, dilated cardiomyopathy, and PI3K-AKT signalling. The hub tumour suppressor gene was FLNA. Immunohistochemistry showed that AKT1, FASN, and FLNA were mainly expressed in PCa cell cytoplasm, while PRDM10 was mainly expressed in nuclei.

Conclusions

Our results identify numerous novel genetic and epigenetic regulatory networks and offer molecular evidence crucial to understanding the pathogenesis of PCa. Aberrantly methylated hub genes, including AKT1, PRDM10, FASN, and FLNA, can be used as biomarkers for accurate PCa diagnosis and treatment. In conclusion, our study suggests that AKT1, PRDM10, and FASN may be tumour promoters and that FLNA may be a tumour suppressor in PCa. We hope these findings will draw more attention to these hub genes in future cancer studies.

Knockdown of SRPX2 inhibits the proliferation, migration, and invasion of prostate cancer cells through the PI3K/Akt/mTOR signaling pathway

Sushi repeat-containing protein X-linked 2 (SRPX2), a novel chondroitin sulfate proteoglycan, is reported to play a critical role in tumorigenesis. However, the expression and functional role of SRPX2 in prostate cancer have not been defined. Thus, the aim of this study was to investigate the expression and functional role of SRPX2 in human prostate cancer. Our results showed that the expression of SRPX2 was obviously increased in human prostate cancer tissues and cell lines. In addition, knockdown of SRPX2 inhibited the proliferation, migration, and invasion of prostate cancer cells, as well as prevented the epithelial-mesenchymal transition process in prostate cancer cells. Mechanically, knockdown of SRPX2 efficiently inhibited the activation of PI3K/Akt/mTOR pathway in prostate cancer cells. Taken together, these data demonstrated that knockdown of SRPX2 inhibits the proliferation and metastasis in human prostate cancer cells, partly through the PI3K/Akt/mTOR signaling pathway. Thus, SRPX2 may be a novel therapeutic target for the treatment of prostate cancer.

Exploring the molecular mechanism associated with breast cancer bone metastasis using bioinformatic analysis and microarray genetic interaction network

BACKGROUND

Bone metastases are common in advanced breast cancer patients and frequently leading to skeletal-related morbidity and deterioration in the quality of life. Although chemotherapy and hormone therapy are able to control the symptoms caused by bone destruction, the underlying molecular mechanisms for the affinity of breast cancer cells towards skeletal bones are still not completely understood.

METHODS

In this study, bioinformatic analysis was performed on patients' microarray gene expression data to explore the molecular mechanism associated with breast cancer bone metastasis. Microarray gene expression profile regarding patients with breast cancer and disseminated tumor cells was downloaded from Gene Expression Omnibus (GEO) database (NCBI, NIH). Raw data were normalized and differently expressed genes were identified by using Significance Analysis of Microarrays (SAM) methods. Protein interaction networks were expanded using String. Moreover, molecular functions, biological processes and signaling pathway enrichment analysis were performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG).

RESULTS

We identified 66 differentially expressed genes. After submitting the set of genes to String, genetic interaction network was expanded, which consisted of 110 nodes and 869 edges. Pathway enrichment analysis suggested that adhesion kinase, ECM-receptor interaction, calcium signaling, Wnt pathways, and PI3K/AKT signaling pathway are highly associated with breast cancer bone metastasis.

CONCLUSION

In this study, we established a microarray genetic interaction network associated with breast cancer bone metastasis. This information provides some potential molecular therapeutic targets for breast cancer initiation and progression.

ST6Gal-I overexpression facilitates prostate cancer progression via the PI3K/Akt/GSK-3β/β-catenin signaling pathway

ST6Gal-I sialyltransferase adds α2,6-linked sialic acids to the terminal ends of glycan chains of glycoproteins and glycolipids. ST6Gal-I is reportedly upregulated in many cancers, including hepatocellular carcinoma, ovarian cancer and breast cancer. However, the expression and function of ST6Gal-I in prostate cancer (PCa) and the mechanism underlying this function remain largely unknown. In this study, we observed that ST6Gal-I expression was upregulated in human PCa tissues compared to non-malignant prostate tissues. High ST6Gal-I expression was positively correlated with Gleason scores, seminal vesicle involvement and poor survival in patients with PCa. ST6Gal-I knockdown in aggressive prostate cancer PC-3 and DU145 cells significantly inhibited the proliferation, growth, migration and invasion capabilities of these cells. ST6Gal-I knockdown decreased the levels of several PI3K/Akt/GSK-3β/ β-catenin pathway components, such as p-PI3K, (Ser473)p-Akt, (Ser9)p-GSK-3β and β-catenin. Furthermore, targeting this pathway with a PI3K inhibitor or Akt RNA interference decreased p-Akt, p-GSK-3β and β-catenin expression, resulting in decreased PC-3 and DU145 proliferation, migration and invasion. Taken together, these results indicate that ST6Gal-I plays a critical role in cell proliferation and invasion via the PI3K/Akt/GSK-3β/β-catenin signaling pathway during PCa progression and that it might be a promising target for PCa prognosis determination and therapy.

Functional role and tobacco smoking effects on methylation of CYP1A1 gene in prostate cancer

Cytochrome P450 (CYP) 1A1 is a phase I enzyme that can activate various compounds into reactive forms and thus, may contribute to carcinogenesis. In this study, we investigated the expression, methylation status, and functional role of CYP1A1 on prostate cancer cells. Increased expression of CYP1A1 was observed in all cancer lines (PC-3, LNCaP, and DU145) compared to BPH-1 (P < 0.05); and was enhanced further by 5-aza-2′-deoxycytidine treatment (P < 0.01). Methylation-specific PCR (MSP) and sequencing of bisulfite-modified DNA of the xenobiotic response element (XRE) enhancer site XRE-1383 indicated promoter methylation as a regulator of CYP1A1 expression. In tissue, microarrays showed higher immunostaining of CYP1A1 in prostate cancer than normal and benign prostatic hyperplasia (BPH; P < 0.001), and methylation analyses in clinical specimens revealed significantly lower methylation levels in cancer compared to BPH at all enhancer sites analyzed (XRE-1383, XRE-983, XRE-895; P < 0.01). Interestingly, smoking affected the XRE-1383 site where the methylation level was much lower in cancer tissues from smokers than non-smokers (P < 0.05). CYP1A1 levels are thus increased in prostate cancer and to determine the functional effect of CYP1A1 on cells, we depleted the gene in LNCaP and DU145 by siRNA. We observe that CYP1A1 knockdown decreased cell proliferation (P < 0.05) and increased apoptosis (P < 0.01) in both cell lines. We analyzed genes affected by CYP1A1 silencing and found that apoptosis-related BCL2 was significantly down-regulated. This study supports an oncogenic role for CYP1A1 in prostate cancer via promoter hypomethylation that is influenced by tobacco smoking, indicating CYP1A1 to be a promising target for prostate cancer treatment.

Combination of Arsenic trioxide and Everolimus (Rad001) synergistically induces both autophagy and apoptosis in prostate cancer cells

The inhibitor of PI3K-AKT-mTOR pathway, such as Rad001, has not shown therapeutic efficacy as a single agent in prostate cancer. Arsenic trioxide induces the autophagic pathway in prostate cancer cells. We identified Arsenic trioxide can synergize with Rad001 to induce cytotoxicity of prostate cancer cells. Moreover, we identified synergistic induction of autophagy and apoptosis as the underlying mechanism. This enhanced autophagic cell death is accompanied by increased Beclin1 mRNA stability as well as upregulation of ATG5-ATG12 conjugate, Beclin1, and LC3-2. Rad001 and ATO also can synergistically inhibit tumors in prostate cancer xenograft animal model. These results identify and validate a novel mechanism to enhance and expand the existing targeted therapeutic agent to treat prostate cancer.