KLF5 downregulation desensitizes castration-resistant prostate cancer cells to docetaxel by increasing BECN1 expression and inducing cell autophagy

Down-regulation of SLC14A1 in prostate cancer activates CDK1/CCNB1 and mTOR pathways and promotes tumor progression

Prostate cancer (PCa) is the most common cancer among men in the United States and the leading cause of cancer-related death. The Solute Carrier Family 14 Member 1 (SLC14A1) is a member of urea transporters which are important for the regulation of urine concentration. However, the physiological significance of SLC14A1 in PCa still remains unclear. In the present study, via bioinformatics analysis and experiments, we found that expression of SLC14A1 is significantly decreased in PCa progression, which could be attributed to hypermethylation on SLC14A1 promoter region. Moreover, its low expression and hypermethylation on SLC14A1 promoter are closely related to the poor prognosis of PCa patients. On the other hand, overexpression of SLC14A1 inhibited cell proliferation and metastasis while its overexpression also suppressed CDK1/CCNB1 pathway and mTOR/MMP-9 signaling pathway. Additionally, SLC14A1 expression is enriched in prostate basal-type cells. In summary, our study indicates that its low expression level and promoter hypermethylation of SLC14A1 may represent novel indicators for PCa progression and prognosis, and SLC14A1 could inhibit the progression of PCa.

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.

Crosstalk between m6A modification and autophagy in cancer

Autophagy is a cellular self-degradation process that plays a crucial role in maintaining metabolic functions in cells and organisms. Dysfunctional autophagy has been linked to various diseases, including cancer. In cancer, dysregulated autophagy is closely associated with the development of cancer and drug resistance, and it can have both oncogenic and oncostatic effects. Research evidence supports the connection between m6A modification and human diseases, particularly cancer. Abnormalities in m6A modification are involved in the initiation and progression of cancer by regulating the expression of oncogenes and oncostatic genes. There is an interaction between m6A modification and autophagy, both of which play significant roles in cancer. However, the molecular mechanisms underlying this relationship are still unclear. m6A modification can either directly inhibit autophagy or promote its initiation, but the complex relationship between m6A modification, autophagy, and cancer remains poorly understood. Therefore, this paper aims to review the dual role of m6A and autophagy in cancer, explore the impact of m6A modification on autophagy regulation, and discuss the crucial role of the m6A modification-autophagy axis in cancer progression and treatment resistance.

Autophagy-related long non-coding RNAs act as prognostic biomarkers and associate with tumor microenvironment in prostate cancer

Aberrant autophagy could promote cancer cells to survive and proliferate in prostate cancer (PCa). LncRNAs play key roles in autophagy regulatory network. We established a prognostic model, which autophagy-related lncRNAs (au-lncRNAs) were used as biomarkers to predict prognosis of individuals with PCa. Depending on au-lncRNAs from the Cancer Genome Atlas and the Human Autophagy Database, a risk score model was created. To evaluate the prediction accuracy, the calibration, Kaplan-Meier, and receiver operating characteristic curves were used. To clarify the biological function, gene set enrichment analyses (GSEA) were performed. Quantitative real-time PCR (qRT-PCR) was employed to determine the au-lncRNAs expression in PCa cell lines and healthy prostate cells for further confirmation. We identified five au-lncRNAs with prognostic significance (AC068580.6, AF131215.2, LINC00996, LINC01125 and LINC01547). The development of a risk scoring model required the utilization of multivariate Cox analysis. According to the model, we categorized PCa individuals into low- and high-risk cohorts. PCa subjects in the high-risk group had a worse disease-free survival rate than those in the low-risk group. The 1-, 3-, and 5-year periods had corresponding areas under curves (AUC) of 0.788, 0.794, and 0.818. The prognosis of individuals with PCa could be predicted by the model with accuracy. Further analysis with GSEA showed that the prognostic model was associated with the tumor microenvironment, including immunotherapy, cancer-related inflammation, and metabolic reprogramming. Four lncRNAs expression in PCa cell lines was greater than that in healthy prostate cells. The au-lncRNA prognostic model has significant clinical implications in prognosis of PCa patient.

The transcriptional activator Klf5 recruits p300-mediated H3K27ac for maintaining trophoblast stem cell pluripotency

The effective proliferation and differentiation of trophoblast stem cells (TSCs) is indispensable for the development of the placenta, which is the key to maintaining normal fetal growth during pregnancy. Kruppel-like factor 5 (Klf5) is implicated in the activation of pluripotency gene expression in embryonic stem cells (ESCs), yet its function in TSCs is poorly understood. Here, we showed that Klf5 knockdown resulted in the downregulation of core TSC-specific genes, consequently causing rapid differentiation of TSCs. Consistently, Klf5-depleted embryos lost the ability to establish TSCs in vitro. At the molecular level, Klf5 preferentially occupied the proximal promoter regions and maintained an open chromatin architecture of key TSC-specific genes. Deprivation of Klf5 impaired the enrichment of p300, a major histone acetyl transferase of H3 lysine 27 acetylation (H3K27ac), and further reduced the occupancy of H3K27ac at promoter regions, leading to decreased transcriptional activity of TSC pluripotency genes. Thus, our findings highlight a novel mechanism of Klf5 in regulating the self-renewal and differentiation of TSCs and provide a reference for understanding placental development and improving pregnancy rates.

KLF5 promotes esophageal squamous cell cancer through the transcriptional activation of FGFBP1

Krüpple-like factor 5 (KLF5) is a zinc-finger-containing transcription factor implicated in several human malignancies, but its potential regulatory mechanisms implicated in esophageal squamous cell carcinoma (ESCC) remain elusive. Here, we show that KLF5 is upregulated in ESCC, where its level was significantly associated with tumor differentiation and lymph node metastasis status. Upregulated KLF5 expression promoted the proliferation, migration, and invasion of ESCC cells. Reduced KLF5 showed the opposite effects. Mechanistically, KLF5 exerts its tumor promotion effect by up-regulating fibroblast growth factor binding protein 1 (FGF-BP1) and snail family transcriptional repressor 2 (SNAIL2). KLF5 binds to the promoter regions of FGF-BP1 and transcriptionally activates its expression. Our study indicated that KLF5 could promote esophageal squamous cell cancer proliferation, migration, and invasion by upregulating FGF-BP1/SNAIL2 signaling. Our work suggests that KLF5 might be a proto-oncogene in ESCC and implicated in ESCC metastasis.

Prostate cancer genetic risk and associated aggressive disease in men of African ancestry

African ancestry is a significant risk factor for prostate cancer and advanced disease. Yet, genetic studies have largely been conducted outside the context of Sub-Saharan Africa, identifying 278 common risk variants contributing to a multiethnic polygenic risk score, with rare variants focused on a panel of roughly 20 pathogenic genes. Based on this knowledge, we are unable to determine polygenic risk or differentiate prostate cancer status interrogating whole genome data for 113 Black South African men. To further assess for potentially functional common and rare variant associations, here we interrogate 247,780 exomic variants for 798 Black South African men using a case versus control or aggressive versus non-aggressive study design. Notable genes of interest include HCP5, RFX6 and H3C1 for risk, and MKI67 and KLF5 for aggressive disease. Our study highlights the need for further inclusion across the African diaspora to establish African-relevant risk models aimed at reducing prostate cancer health disparities.

Targeting autophagy and beyond: Deconvoluting the complexity of Beclin-1 from biological function to cancer therapy

Beclin-1 is the firstly-identified mammalian protein of the autophagy machinery, which functions as a molecular scaffold for the assembly of PI3KC3 (class III phosphatidylinositol 3 kinase) complex, thus controlling autophagy induction and other cellular trafficking events. Notably, there is mounting evidence establishing the implications of Beclin-1 in diverse tumorigenesis processes, including tumor suppression and progression as well as resistance to cancer therapeutics and CSC (cancer stem-like cell) maintenance. More importantly, Beclin-1 has been confirmed as a potential target for the treatment of multiple cancers. In this review, we provide a comprehensive survey of the structure, functions, and regulations of Beclin-1, and we discuss recent advances in understanding the controversial roles of Beclin-1 in oncology. Moreover, we focus on summarizing the targeted Beclin-1-regulating strategies in cancer therapy, providing novel insights into a promising strategy for regulating Beclin-1 to improve cancer therapeutics in the future.

YAP1 inhibits RSL3-induced castration-resistant prostate cancer cell ferroptosis by driving glutamine uptake and metabolism to GSH

High levels of YAP1 and ferroptosis activation in castration-resistant prostate cancer (CRPC) can inhibit CRPC progression and improve its sensitivity toward chemotherapeutics drugs. However, whether YAP1 regulates ferroptosis in CRPC cells and the underlying mechanisms are unknown. The protein levels of YAP1, SLC1A5, and GLS1 in benign prostatic hyperplasia (BPH), prostate cancer (PCa) that did not progress to CRPC, and CRPC tissue samples were evaluated using western blotting. In PC-3 and DU-145 cells, YAP1 overexpression vector, small-interfering RNA, specific inhibitor verteporfin, ferroptosis-inducer RSL3, SLC1A5-inhibitor V-9302, and GLS1-inhibitor CB-839 were used. Immunofluorescence, flow cytometry, dual-luciferase reporter gene, and related kits were used to investigate the effect of YAP1 on the ferroptosis activity in CRPC cells and its underlying mechanisms. YAP1 promoted extracellular glutamine uptake and subsequent production of glutamate and glutathione (GSH), and increases the GPX4 activity. For the activation of ferroptosis by RSL3, YAP1 decreased the levels of reactive oxygen species, malondialdehyde, and lipid peroxidation, and the proportion of dead cells. Mechanistically, YAP1 promoted the expression of SCL1A5 and GLS1 and further increased the GSH levels and GPX4 activity. Thus, inhibiting SLC1A5 or GLS1 activity could alleviate the antagonistic effect of YAP1 on the ferroptosis of RSL3-induced CRPC cells. In CRPC, the YAP1 level is high, which enters the nucleus and promotes the expressions of SLC1A5 and GLS1, thereby promoting cellular glutamine uptake and metabolism to generate glutamate and further synthesizing GSH, increasing GPX4 activity, improving cellular antioxidant capacity, and inhibiting cell death.

High-density lipoprotein regulates angiogenesis by long non-coding RNA HDRACA

Normal high-density lipoprotein (nHDL) can induce angiogenesis in healthy individuals. However, HDL from patients with coronary artery disease undergoes various modifications, becomes dysfunctional (dHDL), and loses its ability to promote angiogenesis. Here, we identified a long non-coding RNA, HDRACA, that is involved in the regulation of angiogenesis by HDL. In this study, we showed that nHDL downregulates the expression of HDRACA in endothelial cells by activating WW domain-containing E3 ubiquitin protein ligase 2, which catalyzes the ubiquitination and subsequent degradation of its transcription factor, Kruppel-like factor 5, via sphingosine 1-phosphate (S1P) receptor 1. In contrast, dHDL with lower levels of S1P than nHDL were much less effective in decreasing the expression of HDRACA. HDRACA was able to bind to Ras-interacting protein 1 (RAIN) to hinder the interaction between RAIN and vigilin, which led to an increase in the binding between the vigilin protein and proliferating cell nuclear antigen (PCNA) mRNA, resulting in a decrease in the expression of PCNA and inhibition of angiogenesis. The expression of human HDRACA in a hindlimb ischemia mouse model inhibited the recovery of angiogenesis. Taken together, these findings suggest that HDRACA is involved in the HDL regulation of angiogenesis, which nHDL inhibits the expression of HDRACA to induce angiogenesis, and that dHDL is much less effective in inhibiting HDRACA expression, which provides an explanation for the decreased ability of dHDL to stimulate angiogenesis.

Interactions between circRNAs and miR-141 in Cancer: From Pathogenesis to Diagnosis and Therapy

The function of non-coding RNAs (ncRNAs) in the pathogenesis and development of cancer is indisputable. Molecular mechanisms underlying carcinogenesis involve the aberrant expression of ncRNAs, including circular RNAs (circRNAs), and microRNAs (miRNAs). CircRNAs are a class of single-stranded, covalently closed RNAs responsible for maintaining cellular homeostasis through their diverse functions. As a part of the competing endogenous RNA (ceRNAs) network, they play a central role in the regulation of accessibility of miRNAs to their mRNA targets. The interplay between these molecular players is based on the primary role of circRNAs that act as miRNAs sponges, and the circRNA/miRNA imbalance plays a central role in different pathologies including cancer. Herein, we present the latest state of knowledge about interactions between circRNAs and miR-141, a well-known member of the miR-200 family, in malignant transformation, with emphasis on the biological role of circRNA/miR-141/mRNA networks as a future target for novel anti-cancer therapies.

KLF6 alleviates hepatic ischemia-reperfusion injury by inhibiting autophagy

Hepatic ischemia-reperfusion (I/R) injury, a common clinical complication of liver transplantation, gravely affects patient prognosis. Krüppel-like factors (KLFs) constitute a family of C2/H2 zinc finger DNA-binding proteins. KLF6, a member of the KLF protein family, plays crucial roles in proliferation, metabolism, inflammation, and injury responses; however, its role in HIR is largely remains unknown. After I/R injury, we found that KLF6 expression in mice and hepatocytes was significantly upregulated. Mice were then subjected to I/R following injection of shKLF6- and KLF6-overexpressing adenovirus through the tail vein. KLF6 deficiency markedly exacerbated liver damage, cell apoptosis, and activation of hepatic inflammatory responses, whereas hepatic overexpression of KLF6 in mice produced the opposite results. In addition, we knocked out or overexpressed KLF6 in AML12 cells before exposing them to a hypoxia-reoxygenation challenge. KLF6 knockout decreased cell viability and increased hepatocyte inflammation, apoptosis, and ROS, whereas KLF6 overexpression had the opposite effects. Mechanistically, KLF6 inhibited the overactivation of autophagy at the initial stage, and the regulatory effect of KLF6 on I/R injury was autophagy-dependent. CHIP-qPCR and luciferase reporter gene assays confirmed that KLF6 bound to the promoter region of Beclin1 and inhibited its transcription. Additionally, KLF6 activated the mTOR/ULK1 pathway. Finally, we performed a retrospective analysis of the clinical data of liver transplantation patients and identified significant associations between KLF6 expression and liver function following liver transplantation. In conclusion, KLF6 inhibited the overactivation of autophagy via transcriptional regulation of Beclin1 and activation of the mTOR/ULK1 pathway, thereby protecting the liver from I/R injury. KLF6 is expected to serve as a biomarker for estimating the severity of I/R injury following liver transplantation.

JMJD2A participates in cytoskeletal remodeling to regulate castration-resistant prostate cancer docetaxel resistance

BACKGROUND

To investigate underlying mechanism of JMJD2A in regulating cytoskeleton remodeling in castration-resistant prostate cancer (CRPC) resistant to docetaxel.

METHODS

Tissue samples from CRPC patients were collected, and the expression of JMJD2A, miR-34a and cytoskeleton remodeling-related proteins were evaluated by qPCR, western blot and immunohistochemistry, and pathological changes were observed by H&E staining. Further, JMJD2A, STMN1 and TUBB3 were knocked down using shRNA in CRPC cell lines, and cell viability, apoptosis and western blot assays were performed. The interaction between miR-34a/STMN1/β3-Tubulin was analyzed with dual-luciferase reporter and co-immunoprecipitation assays.

RESULTS

In clinical experiment, the CRPC-resistant group showed higher expression of JMJD2A, STMN1, α-Tubulin, β-Tubulin and F-actin, and lower expression of miR-34a and β3-Tubulin compared to the sensitive group. In vitro experiments showed that JMJD2A could regulate cytoskeletal remodeling through the miR-34a/STMN1/β3-Tubulin axis. The expression of miR-34a was elevated after knocking down JMJD2A, and miR-34a targeted STMN1. The overexpression of miR-34a was associated with a decreased expression of STMN1 and elevated expression of β3-Tubulin, which led to the disruption of the microtubule network, decreased cancer cell proliferation, cell cycle arrest in the G0/G1 phase, and increased apoptosis.

CONCLUSION

JMJD2A promoted docetaxel resistance in prostate cancer cells by regulating cytoskeleton remodeling through the miR-34a/STMN1/β3-Tubulin axis.

New insights into KLFs and SOXs in cancer pathogenesis, stemness, and therapy

Despite the development of cancer therapies, the success of most treatments has been impeded by drug resistance. The crucial role of tumor cell plasticity has emerged recently in cancer progression, cancer stemness and eventually drug resistance. Cell plasticity drives tumor cells to reversibly convert their cell identity, analogous to differentiation and dedifferentiation, to adapt to drug treatment. This phenotypical switch is driven by alteration of the transcriptome. Several pluripotent factors from the KLF and SOX families are closely associated with cancer pathogenesis and have been revealed to regulate tumor cell plasticity. In this review, we particularly summarize recent studies about KLF4, KLF5 and SOX factors in cancer development and evolution, focusing on their roles in cancer initiation, invasion, tumor hierarchy and heterogeneity, and lineage plasticity. In addition, we discuss the various regulation of these transcription factors and related cutting-edge drug development approaches that could be used to drug "undruggable" transcription factors, such as PROTAC and PPI targeting, for targeted cancer therapy. Advanced knowledge could pave the way for the development of novel drugs that target transcriptional regulation and could improve the outcome of cancer therapy.

Multi-omics data reveals novel impacts of human papillomavirus integration on the epigenomic and transcriptomic signatures of cervical tumorigenesis

Integration of human papilloma virus (HPV) DNA into the human genome may progressively contribute to cervical carcinogenesis. To explore how HPV integration affects gene expression by altering DNA methylation during carcinogenesis, we analyzed a multiomics dataset for cervical cancer. We obtained multiomics data by HPV-capture sequencing, RNA sequencing, and Whole Genome Bisulfite Sequencing from 50 patients with cervical cancer. We detected 985 and 485 HPV-integration sites in matched tumor and adjacent paratumor tissues. Of these, LINC00486 (n = 19), LINC02425 (n = 11), LLPH (n = 11), PROS1 (n = 5), KLF5 (n = 4), LINC00392 (n = 3), MIR205HG (n = 3) and NRG1 (n = 3) were identified as high-frequency HPV-integrated genes, including five novel recurrent genes. Patients at clinical stage II had the highest number of HPV integrations. E6 and E7 genes of HPV16 but not HPV18 showed significantly fewer breakpoints than random distribution. HPV integrations occurring in exons were associated with altered gene expression in tumor tissues but not in paratumor tissues. A list of HPV-integrated genes regulated at transcriptomic or epigenetic level was reported. We also carefully checked the candidate genes with regulation pattern correlated in both levels. HPV fragments integrated at MIR205HG mainly came from the L1 gene of HPV16. RNA expression of PROS1 was downregulated when HPV integrated in its upstream region. RNA expression of MIR205HG was elevated when HPV integrated into its enhancer. The promoter methylation levels of PROS1 and MIR205HG were all negatively correlated with their gene expressions. Further experimental validations proved that upregulation of MIR205HG could promote the proliferative and migrative abilities of cervical cancer cells. Our data provides a new atlas for epigenetic and transcriptomic regulations regarding HPV integrations in cervical cancer genome. We demonstrate that HPV integration may affect gene expression by altering methylation levels of MIR205HG and PROS1. Our study provides novel biological and clinical insights into HPV-induced cervical cancer.

Paclitaxel and docetaxel resistance in prostate cancer: Molecular mechanisms and possible therapeutic strategies

Prostate cancer is among most malignant tumors around the world and this urological tumor can be developed as result of genomic mutations and their accumulation during progression towards advanced stage. Due to lack of specific symptoms in early stages of prostate cancer, most cancer patients are diagnosed in advanced stages that tumor cells display low response to chemotherapy. Furthermore, genomic mutations in prostate cancer enhance the aggressiveness of tumor cells. Docetaxel and paclitaxel are suggested as well-known compounds for chemotherapy of prostate tumor and they possess a similar function in cancer therapy that is based on inhibiting depolymerization of microtubules, impairing balance of microtubules and subsequent delay in cell cycle progression. The aim of current review is to highlight mechanisms of paclitaxel and docetaxel resistance in prostate cancer. When oncogenic factors such as CD133 display upregulation and PTEN as tumor-suppressor shows decrease in expression, malignancy of prostate tumor cells enhances and they can induce drug resistance. Furthermore, phytochemicals as anti-tumor compounds have been utilized in suppressing chemoresistance in prostate cancer. Naringenin and lovastatin are among the anti-tumor compounds that have been used for impairing progression of prostate tumor and enhancing drug sensitivity. Moreover, nanostructures such as polymeric micelles and nanobubbles have been utilized in delivery of anti-tumor compounds and decreasing risk of chemoresistance development. These subjects are highlighted in current review to provide new insight for reversing drug resistance in prostate cancer.

Fast Mimicking Diets and Other Innovative Nutritional Interventions to Treat Patients with Breast Cancer

The impact of nutritional patterns on the risk of breast cancer (BC) is well investigated in the oncology literature, including the type of diets and caloric intake. While obesity and elevated body mass index are well-reported critical risk factors of BC occurrence, there is an expanding area of oncology assessing the impact of caloric intake and nutritional patterns in patients with cancer. Caloric restriction and fast mimicking alimentary regimens have been consistently reported to improve survival outcomes based on preclinical models. Moreover, emerging clinical evidence has paved the way for new metabolic approaches for the treatment of BC, in addition to the established therapeutic arsenal or as alternative options. In this chapter, our aim is to discuss the principal strategies of metabolic manipulation through nutritional interventions for patients with BC as an innovative area of cancer therapy.

Kruppel-like factor 2 contributes to blood-spinal cord barrier integrity and functional recovery from spinal cord injury by augmenting autophagic flux

Background: Increasing evidence suggests that acute traumatic spinal cord injury (SCI)-induced defects in autophagy and autophagy-lysosomal pathway (ALP) may contribute to endothelial barrier disruption following injury. Recently, Kruppel-like factor 2 (KLF2) was reported as a key molecular switch on regulating autophagy. Whether KLF2 coordinates endothelial endothelial ALP in SCI is not known. Methods: Genetic manipulations of KLF2 were performed in bEnd.3 cells and SCI model. Western blot, qRT-PCR, immunofluorescence staining and Lyso-Tracker Red staining, Evans blue dye extravasation, behavioral assessment via Basso mouse scale (BMS), electrophysiology and footprint analysis were performed. Results: In SCI, autophagy flux disruption in endothelial cells contributes to TJ proteins degradation, leading to blood-spinal cord barrier (BSCB) impairment. Furthermore, the KLF2 level was decreased in SCI, overexpression of which alleviated TJ proteins loss and BSCB damage, which improve motor function recovery in SCI mice, while knockdown of KLF2 displayed the opposite effects. At the molecular level, KLF2 overexpression alleviated the TJ proteins degradation and the endothelial permeability by tuning the ALP dysfunction caused by SCI and oxygen glucose deprivation (OGD). Conclusions: Endothelial KLF2 as one of the key contributors to SCI-mediated ALP dysfunction and BSCB disruption. KLF2 could be a promising pharmacological target for the management and treatment of SCI.

Kruppel-like Factors in Skeletal Physiology and Pathologies

Kruppel-like factors (KLFs) belong to a large group of zinc finger-containing transcription factors with amino acid sequences resembling the Drosophila gap gene Krüppel. Since the first report of molecular cloning of the KLF family gene, the number of KLFs has increased rapidly. Currently, 17 murine and human KLFs are known to play crucial roles in the regulation of transcription, cell proliferation, cellular differentiation, stem cell maintenance, and tissue and organ pathogenesis. Recent evidence has shown that many KLF family molecules affect skeletal cells and regulate their differentiation and function. This review summarizes the current understanding of the unique roles of each KLF in skeletal cells during normal development and skeletal pathologies.

LINC00665 affects the malignant biological behavior of ovarian cancer via the miR-148b-3p/KLF5

This study investigated the expression and clinical significance of long intergenic noncoding RNA 00665 (LINC00665) in ovarian cancer (OC), as well as its effect on the malignant biological behavior of OC cells. The expression of LINC00665, miR-148b-3p, and Krüppel-like factor 5 (KLF5) in OC tissues and cells were determined by RT-qPCR. Western blot was used to detect the protein expression of KLF5. The expression patterns of LINC00665 in nuclear and cytoplasm fractions were undertaken using RT-qPCR. In addition, CCK-8 assay, clone formation assay, transwell, scratch test, and flow cytometry were respectively used to detect the cell activity, proliferation, invasiveness, healing of cells, and apoptosis rate of OC cells. Furthermore, the interactions between LINC00665 and miR-148b-3p and between miR-148b-3p and KLF5 were verified by the luciferase reporter assay, and the correlations among these three genes were analyzed. LINC00665 expression was upregulated both in OC cell lines and tissues. Si-LINC00665 inhibited cell proliferation, invasion, and migration and induced apoptosis to a certain extent. The subcellular fraction assay revealed LINC00665 to be located mainly in the cytoplasm. miR-148b-3p was a target of LINC00665, and KLF5 was directly targeted by miR-148b-3p. Si-LINC00665 inhibited KLF5 expression, miR-148b-3p inhibitor promoted KLF5 expression, and si-KLF5 inhibited LINC00665 expression. Interestingly, the expression of LINC00665 was reversely associated with miR-148b-3p expression but positively correlated with KLF5. Furthermore, miR-148b-3p expression was negatively correlated with KLF5. In addition, si-KLF5 inhibited the malignant biological behavior of OC cells, whereas miR-148b-3p inhibitor had the opposite effect. Most importantly, the si-LINC00665 could reverse the promotion effect of the miR-148b-3p inhibitor on the malignant biological behavior of OC cells. LINC00665 can be used as an effective prognostic indicator of OC, which has the potential to be a new therapeutic target.

AMPK's double-faced role in advanced stages of prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer deaths in men. Unfortunately, a very limited number of drugs are available for the relapsed and advanced stages of PCa, adding only a few months to survival; therefore, it is vital to develop new drugs. 5´ AMP-activated protein kinase (AMPK) is a master regulator of cell metabolism. It plays a significant role in the metabolism of PCa; hence, it can serve well as a treatment option for the advanced stages of PCa. However, whether this pathway contributes to cancer cell survival or death remains unknown. The present study reviews the possible pathways by which AMPK plays role in the advanced stages of PCa, drug resistance, and metastasis: (1) AMPK has a contradictory role in promoting glycolysis and the Warburg effect which are correlated with cancer stem cells (CSCs) survival and advanced PCa. It exerts its effect by interacting with hypoxia-induced factor 1 (HIF1) α, pyruvate kinase 2 (PKM2), glucose transporter (GLUT) 1 and pyruvate dehydrogenase complex (PDHC), which are key regulators of glycolysis; however, whether it promotes or discourage glycolysis is not conclusive. It can also exert an anti-CSC effect by negative regulation of NANOG and epithelial-mesenchymal transition (EMT) transcription factors, which are the major drivers of CSC maintenance; (2) the regulatory effect of AMPK on autophagy is also noticeable. Androgen receptors' expression increases AMPK activation through Calcium/calmodulin-dependent protein kinase 2 (CaMKK2) and induces autophagy. In addition, AMPK itself increases autophagy by downregulating the mammalian target of rapamycin complex (mTORC). However, whether increased autophagy inhibits or promotes cell death and drug resistance is contradictory. This study reveals that there are numerous pathways other than cell metabolism by which AMPK exerts its effects in the advanced stages of PCa, making it a priceless treatment target. Finally, we mention some drugs developed to treat the advanced stages of PCa by acting on AMPK.

RP1-59D14.5 triggers autophagy and represses tumorigenesis and progression of prostate cancer via activation of the Hippo signaling pathway

Prostate cancer (PCa) is one of the major malignant tumors among men worldwide. Long noncoding RNAs (lncRNAs) have been documented as important modulators in human cancers, including PCa. In our study, we investigated the role and potential mechanism of RP1-59D14.5 in PCa. RP1-59D14.5 expressed at a low level in PCa cells. Gain-of-function assays including colony formation and transwell assays displayed that RP1-59D14.5 overexpression repressed PCa cell proliferation, migration, and invasion. Besides, RP1-59D14.5 up-regulation induced autophagy in PCa cells. Mechanically, luciferase reporter assays and western blot verified that RP1-59D14.5 activated the Hippo pathway in PCa cells. Through RNA-binding protein immunoprecipitation (RIP) and RNA pull-down assays, we validated that RP1-59D14.5 functioned as a competing endogenous RNA (ceRNA) to regulate large tumor suppressor kinase 1/2 (LATS1/2) via targeting miR-147a. Moreover, RP1-59D14.5 recruited HUR to promote casein kinase 1 (CK1) expression. Collectively, RP1-59D14.5 promoted yes-associated protein (YAP) degradation to activate the Hippo pathway in PCa progression via targeting the miR-147a/LATS1/2 axis and recruiting HUR to promote the interaction of CK1 and β-transducin repeat-containing protein (βTrCP). These results implied that RP1-59D14.5 acted as a tumor suppressor in PCa, which might be a target for PCa treatment.

Long non-coding RNA PCDRlnc1 confers docetaxel resistance in prostate cancer by promoting autophagy

Docetaxel resistance seriously affects its clinical application in prostate cancer (PCa). Long noncoding RNAs (lncRNAs) influence the chemosensitivity of various cancers. However, the potential involvement of lncRNAs in docetaxel sensitivity remains largely unknown in PCa. In the present study, we used RNA sequencing to compare the expression profiles of lncRNAs in docetaxel-resistant PCa cells and their parental cells and identified a novel lncRNA, ENSG00000234147, termed as PCa docetaxel resistance-associated lncRNA1 (PCDRlnc1). Our results indicated that PCDRlnc1 is closely associated with docetaxel resistance in PCa, and PCDRlnc1 knockout markedly sensitized the resistant cells to docetaxel in vitro and in vivo. In addition, PCDRlnc1 inhibition markedly suppressed docetaxel-induced autophagy. Conversely, PCDRlnc1 overexpression promoted autophagy. Mechanistically, PCDRlnc1 interacted with UHRF1 (ubiquitin-like with plant homeodomain and ring finger domains 1) and promoted its transcription level in PCa cells, leading to the activation of autophagic Beclin-1 signaling. Together, our data demonstrate that PCDRlnc1 is a novel key regulator of PCa docetaxel resistance, suggesting that it may be used as a potential biomarker of docetaxel resistance and therapeutic target in PCa.

Targeting autophagy in prostate cancer: preclinical and clinical evidence for therapeutic response

Prostate cancer is a leading cause of death worldwide and new estimates revealed prostate cancer as the leading cause of death in men in 2021. Therefore, new strategies are pertinent in the treatment of this malignant disease. Macroautophagy/autophagy is a “self-degradation” mechanism capable of facilitating the turnover of long-lived and toxic macromolecules and organelles. Recently, attention has been drawn towards the role of autophagy in cancer and how its modulation provides effective cancer therapy. In the present review, we provide a mechanistic discussion of autophagy in prostate cancer. Autophagy can promote/inhibit proliferation and survival of prostate cancer cells. Besides, metastasis of prostate cancer cells is affected (via induction and inhibition) by autophagy. Autophagy can affect the response of prostate cancer cells to therapy such as chemotherapy and radiotherapy, given the close association between autophagy and apoptosis. Increasing evidence has demonstrated that upstream mediators such as AMPK, non-coding RNAs, KLF5, MTOR and others regulate autophagy in prostate cancer. Anti-tumor compounds, for instance phytochemicals, dually inhibit or induce autophagy in prostate cancer therapy. For improving prostate cancer therapy, nanotherapeutics such as chitosan nanoparticles have been developed. With respect to the context-dependent role of autophagy in prostate cancer, genetic tools such as siRNA and CRISPR-Cas9 can be utilized for targeting autophagic genes. Finally, these findings can be translated into preclinical and clinical studies to improve survival and prognosis of prostate cancer patients.

• Prostate cancer is among the leading causes of death in men where targeting autophagy is of importance in treatment;

• Autophagy governs proliferation and metastasis capacity of prostate cancer cells;

• Autophagy modulation is of interest in improving the therapeutic response of prostate cancer cells;

• Molecular pathways, especially involving non-coding RNAs, regulate autophagy in prostate cancer;

• Autophagy possesses both diagnostic and prognostic roles in prostate cancer, with promises for clinical application.

The circROBO1/KLF5/FUS feedback loop regulates the liver metastasis of breast cancer by inhibiting the selective autophagy of afadin

BACKGROUND

Metastasis causes the majority of cancer-related deaths worldwide. Increasing studies have revealed that circRNAs are associated with the carcinogenesis and metastasis of many cancers. Nevertheless, the biological mechanisms of circRNAs in breast cancer (BC) liver metastasis remain extremely ambiguous.

METHODS

In this study, we identified circROBO1 from three pairs of primary BC and metastatic liver sites by RNA sequencing. FISH assays and RT-qPCR were conducted to validate the existence and expression of circROBO1. The oncogenic role of circROBO1 was demonstrated both in vitro and in vivo. Western blot, ChIP, RIP, RNA pull-down, and dual-luciferase reporter assays were used to confirm the interaction of the feedback loop among circROBO1, miR-217-5p, KLF5, and FUS. Meanwhile, the regulation of selective autophagy was investigated by immunofluorescence, CoIP, and western blot.

RESULTS

In this study, upregulated expression of circROBO1 was found in BC-derived liver metastases and was correlated with poor prognosis. Knockdown of circROBO1 strikingly inhibited the proliferation, migration, and invasion of BC cells, whereas overexpression of circROBO1 showed the opposite effects. Moreover, overexpression of circROBO1 promoted tumor growth and liver metastasis in vivo. Further research revealed that circROBO1 could upregulate KLF5 by sponging miR-217-5p, allowing KLF5 to activate the transcription of FUS, which would promote the back splicing of circROBO1. Therefore, a positive feedback loop comprising circROBO1/KLF5/FUS was formed. More importantly, we found that circROBO1 inhibited selective autophagy of afadin by upregulating KLF5.

CONCLUSIONS

Our results demonstrated that circROBO1 facilitates the carcinogenesis and liver metastasis of BC through the circROBO1/KLF5/FUS feedback loop, which inhibits the selective autophagy of afadin by suppressing the transcription of BECN1. Therefore, circROBO1 could be used not only as a potential prognostic marker but also as a therapeutic target in BC.

WW Domain-Containing E3 Ubiquitin Protein Ligase 1: A Self-Disciplined Oncoprotein

WW domain-containing E3 ubiquitin protein ligase 1 (WWP1) is a member of C2-WW-HECT E3 ligase family. Although it may execute carcinostatic actions in some scenarios, WWP1 functions as an oncoprotein under most circumstances. Here, we comprehensively review reports on regulation of WWP1 and its roles in tumorigenesis. We summarize the WWP1-mediated ubiquitinations of diverse proteins and the signaling pathways they involved, as well as the mechanisms how they affect cancer formation and progression. According to our analysis of database, in combination with previous reports, we come to a conclusion that WWP1 expression is augmented in various cancers. Gene amplification, as well as expression regulation mediated by molecules such as non-coding RNAs, may account for the increased mRNA level of WWP1. Regulation of enzymatic activity is another important facet to upregulate WWP1-mediated ubiquitinations. Based on the published data, we conclude that WWP1 employs interactions between multiple domains to autoinhibit its polyubiquitination activity in a steady state. Association of some substrates can partially release certain autoinhibition-related domains and make WWP1 have a moderate activity of polyubiquitination. Some cancer-related mutations can fully disrupt the inhibitory interactions and make WWP1 hyperactive. High expression level or hyperactivation of WWP1 may abnormally enhance polyubiquitinations of some oncoproteins or tumor suppressors, such as ΔNp63α, PTEN and p27, and ultimately promote cell proliferation, survival, migration and invasion in tumorigenesis. Given the dysregulation and oncogenic functions of WWP1 in some cancer types, it is promising to explore some therapeutic inhibitors to tune down its activity.

Exosome-mediated transfer of SNHG7 enhances docetaxel resistance in lung adenocarcinoma

Long noncoding RNA (lncRNA) small nucleolar RNA host gene 7 (SNHG7) has been widely reported in various cancers, including lung adenocarcinoma (LUAD). However, it is largely unknown whether SNHG7 is involved in docetaxel resistance of LUAD. In the current study, we identified the high expression of SNHG7 in docetaxel-resistant cells. Through functional assays, we determined that silencing of SNHG7 decreased IC₅₀ value of LUAD cells to docetaxel and suppressed proliferation and autophagy in LUAD cells, and reversed M2 polarization in macrophages. Mechanistically, we uncovered that SNHG7 promoted autophagy via recruiting human antigen R (HuR) to stabilize autophagy-related genes autophagy related 5 (ATG5) and autophagy related 12 (ATG12). Moreover, exosomal SNHG7 was transmitted from docetaxel-resistant LUAD cells to parental LUAD cells and thus facilitated docetaxel resistance. Additionally, exosomal SNHG7 activated the phosphatidylinositol 3-kinase (PI3K)/AKT pathway to promote M2 polarization in macrophages via recruiting cullin 4A (CUL4A) to induce ubiquitination and degradation of phosphatase and tensin homolog (PTEN). Taken together, we concluded that exosomal SNHG7 enhances docetaxel resistance of LUAD cells through inducing autophagy and macrophage M2 polarization. All findings in the study suggested that SNHG7 may be a promising target for relieving docetaxel resistance in LUAD.

Autophagy up-regulated by MEK/ERK promotes the repair of DNA damage caused by aflatoxin B1

Aflatoxin B1 (AFB1), a kind of mycotoxin, exerts its cytotoxicity by increasing the oxidative damage of target organs, especially the liver. In vivo and in vitro experiments were carried out to elucidate the toxic mechanism of AFB1. The results of MTT, cloning-formation, flow cytometry, immunocytochemistry, Reverse transcription PCR (RT-PCR) and western blot showed that AFB1 activated NOX2 gp91 phox, inhibited proliferation and migration, and blocked cell cycle at G0/G1 period of HHL-5 cells. Autophagy promoted the repair of NOX2-dependent DNA damage. NOX2/gp91 phox mainly activates MEK/ERK pathway and then up-regulates autophagy. In vivo experiments have shown that AFB1 (0.75 mg/kg daily orally, 4 weeks) had no significant changes in the size and shape of the liver in mice. However, these treatments lead to structural abnormalities of hepatocytes and DNA damage. In summary, AFB1 caused intracellular oxidative stress and DNA damage, NOX2/gp91-phox activates the MEK/ERK pathway, and upregulated autophagy to promote the repair of DNA damage. We concluded that by increasing the level of autophagy, the ability of anti-AFB1 toxicity of liver can be increased.

The roles and regulation of the KLF5 transcription factor in cancers

Krüppel‐like factor 5 (KLF5) is a member of the KLF family. Recent studies have suggested that KLF5 regulates the expression of a large number of new target genes and participates in diverse cellular functions, such as stemness, proliferation, apoptosis, autophagy, and migration. In response to multiple signaling pathways, various transcriptional modulation and posttranslational modifications affect the expression level and activity of KLF5. Several transgenic mouse models have revealed the physiological and pathological functions of KLF5 in different cancers. Studies of KLF5 will provide prognostic biomarkers, therapeutic targets, and potential drugs for cancers.

Silenced long non-coding RNA activated by DNA damage elevates microRNA-495-3p to suppress atherosclerotic plaque formation via reducing Krüppel-like factor 5

OBJECTIVE

Atherosclerosis (AS) is an inflammatory disease and the formation of atherosclerotic plaque plays a critical role in AS progression. We aimed to investigate the effect of long non-coding RNA (lncRNA) activated by DNA damage (NORAD)/microRNA-495-3p (miR-495-3p)/Krüppel-like factor 5 (KLF5) axis on atherosclerotic plaque formation.

METHODS

The ApoE^-/- mice were fed a high-fat diet to construct AS mouse models and the modeled mice were treated with altered NORAD, miR-495-3p or KLF5. NORAD, miR-495-3p and KLF5 expression in mouse aorta tissues were evaluated, and the levels of inflammatory factors, oxidative stress factors, endothelial function indices and blood lipid in mice were all determined. The atherosclerotic plaque area, lipid deposition area, collagen fibers and CD68 expression in mouse aorta tissues were assessed. The regulatory relation between NORAD and miR-495-3p, and the target relation between miR-495-3p and KLF5 were confirmed.

RESULTS

NORAD and KLF5 were increased whereas miR-495-3p was decreased in atherosclerotic mouse aortas. Inhibited NORAD or elevated miR-495-3p suppressed inflammation, oxidative stress, endothelial dysfunction, blood lipid level, atherosclerotic plaque area, collagen fibers and CD68 expression in atherosclerotic mouse aortas. Effects of elevated miR-495-3p on atherosclerotic mice could be reversed by up-regulation of KLF5. NORAD served as a sponge of miR-495-3p and miR-495-3p directly targeted KLF5.

CONCLUSION

Silenced NORAD elevated miR-495-3p to suppress atherosclerotic plaque formation via reducing KLF5. Findings in our research may be helpful for exploring molecular mechanisms of AS.

Autophagy-induced p62 accumulation is required for curcumol to regulate KLF5-mediated angiogenesis in liver sinusoidal endothelial cells

Liver pathological angiogenesis is considered to be one of the key events in the development of liver fibrosis. Autophagy is a defense and stress regulation mechanism. However, whether autophagy regulates pathological angiogenesis in liver fibrosis is still questionable. Here, we aimed to study how curcumol regulated liver sinusoidal endothelial cells (LSECs) angiogenesis through autophagy. We found that curcumol (10, 20 and 40 μM) could inhibit the expression of angiogenesis markers in the LSECs. Importantly, we showed that curcumol might influence LSEC pathological angiogenesis by regulating autophagy level. Furthermore, we indicated that the transcription factor Krüppel-like factor 5 (KLF5) was considered as a key target for curcumol to regulate LSEC angiogenesis. Interestingly, we also suggested that autophagy was as a potential mechanism for curcumol to restrain KLF5 expression. Increased autophagy level could impair the suppression effect of curcumol on KLF5. Fascinatingly, our results indicated that curcumol inhibited autophagy and led to p62 accumulation, which might be a regulation mechanism of KLF5 degradation. Finally, in mice liver fibrosis model, we unanimously showed that curcumol (30 mg/kg) inhibited pathological angiogenesis by reducing LSEC autophagy level and suppressing KLF5 expression. Collectively, these results provided a deeper insight into the molecular mechanism of curcumol to inhibit LSEC pathological angiogenesis during liver fibrosis.

HOTAIR and androgen receptor synergistically increase GLI2 transcription to promote tumor angiogenesis and cancer stemness in renal cell carcinoma

Tumor angiogenesis is a major characteristic of renal cell carcinoma (RCC). Herein, we report a novel mechanism of how lncRNA and androgen receptor (AR) drive the Hedgehog pathway to promote tumor angiogenesis in RCC. We found that the high expression of lncRNA HOTAIR in RCC is associated with poor prognosis. Moreover, HOTAIR and AR form a feedback loop to promote the expression of each other. Interestingly, we also found that in RCC, HOTAIR is associated with the Hedgehog pathway, especially GLI2, via bioinformatics analysis. Furthermore, HOTAIR promotes GLI2 expression in the presence of AR. Mechanistically, HOTAIR interacts with AR and they cooperatively bind to GLI2 promoter and increase its transcription activity. We further confirmed how HOTAIR-AR axis regulates GLI2 expression by analyzing its function in RCC cells and found that HOTAIR and AR synergistically enhanced the expression of GLI2 downstream genes, such as VEGFA, PDGFA, and cancer stem cell transcription factors, and promoted tumor angiogenesis and cancer stemness in RCC cells both in vitro and in tumor xenografts. Overall, these findings suggest that HOTAIR and GLI2 could be novel therapeutic targets against RCC.

BAP1 antagonizes WWP1-mediated transcription factor KLF5 ubiquitination and inhibits autophagy to promote melanoma progression

Accumulating evidence revealed the abnormal expression of KLF5 in human cancers while its role in melanoma remains uncharacterized. This study aimed to explore the role of KLF5 in the proliferation and metastasis of melanoma. Bioinformatics analysis was performed to detect WWP1, BAP1 and KLF5 expression in melanoma, followed by expression determination on clinical tissues from melanoma patients and cancer cells. The cancer cells were infected with lentivirus expressing KLF5 or BAP1 while PI3K, AKT and mTOR expression was detected and autophagy was observed. Treated cells were injected to mice when tumor growth was measured and autophagy-related protein was detected. Plasmids expressing WWP1 and Ub-K48 were co-transfected into treated melanoma cells while immunoprecipitation assay was performed to determine the interaction among KLF5, WWP1, and BAP1. WWP1 was poorly expressed in melanoma cells and tissues whereas KLF5 was highly expressed and was positively correlated to poor prognosis. KLF5 promoted melanoma cell malignant phenotypes as well as inhibited autophagy. Interestingly, KLF5 contributed to activation of PI3K-AKT-mTOR signaling pathway, thereby inhibiting autophagy in melanoma cells. WWP1 mediated K48-linked ubiquitination of KLF5 to promote its degradation, and BAP1 antagonized this modification and stabilized KLF5 protein expression. Besides, BAP1 promoted KLF5-mediated growth of melanoma in vivo. Taken altogether, BAP1 antagonized WWP1-mediated ubiquitination of KLF5 to inhibit autophagy and promote melanoma development.

Mesenchymal stem cells desensitize castration-resistant prostate cancer to docetaxel chemotherapy via inducing TGF-β1-mediated cell autophagy

Background

Mesenchymal stem cells (MSCs) have been proved to drive castration resistant prostate cancer (CRPC). In this study, we aim to investigate the contribution of MSCs to the development of docetaxel resistance in CRPC cells and its potential mechanisms.

Methods

The effect of MSCs on CRPC cells resistance to docetaxel was determined using in vivo and in vitro approaches. CCK8 and PI/Annexin V-FITC assay were used to examined the cell viability and apoptosis. The concentration of transforming growth factor-β1 was measured by enzyme-linked immunosorbent assay and small interfering RNA was used for functional analyses.

Results

MSCs significantly reduced the sensitivity of CRPC cells to docetaxel-induced proliferation inhibition and apoptosis promotion in vivo and in vitro. CRPC cells cocultured with MSCs under docetaxel administration have an increased autophagy activation, while autophagy inhibitor could effectively reversed MSCs-induced resistance to docetaxel. Additionally, MSCs-induced CRPC cell autophagy increase under docetaxel administration depends on MSCs secreting TGF-β1 and inhibition of TGF-β1 secretion in MSCs could consequently increase the sensitivity of CRPC cells to docetaxel.

Conclusions

These results suggest that docetaxel administrated CRPC cells may elicit MSCs secreting TGF-β1 increase, which desensitizes CRPC to docetaxel chemotherapy accelerating chemoresistance occurrence via inducing cell autophagy.

Krupple-Like Factor 5 is a Potential Therapeutic Target and Prognostic Marker in Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy. Despite current therapeutic and surgical options, advanced EOC shows poor prognosis. Identifying novel molecular therapeutic targets is highly needed in the management of EOC. Krupple-like factor 5 (KLF5), a zinc-finger transcriptional factor, is highly expressed in a variety of cancer types. However, its role and expression in EOC is not fully illustrated. Immunohistochemical analysis was performed to assess KLF5 protein expression in 425 primary EOC samples using tissue microarray. We also addressed the function of KLF5 in EOC and its interaction with signal transducer and activator of transcription 3 (STAT3) signaling pathway. We found that KLF5 overexpressed in 53% (229/425) of EOC samples, and is associated with aggressive markers. Forced expression of KLF5 enhanced cell growth in low expressing EOC cell line, MDAH2774. Conversely, knockdown of KLF5 reduced cell growth, migration, invasion and progression of epithelial to mesenchymal transition in KLF5 expressing cell lines, OVISE and OVSAHO. Importantly, silencing of KLF5 decreased the self-renewal ability of spheroids generated from OVISE and OVSAHO cell lines. In addition, downregulation of KLF5 potentiated the effect of cisplatin to induce apoptosis in these cell lines. These data reveals the pro-tumorigenic role of KLF5 in EOC and uncover its role in activation of STAT3 signaling pathway, suggesting the importance of KLF5 as a potential therapeutic target for EOC therapy.

Mechanisms of docetaxel resistance in prostate cancer: The key role played by miRNAs

One of the main problems with the treatment of metastatic prostate cancer is that, despite an initial positive response, the majority of patients develop resistance and progress. In particular, the resistance to docetaxel, the gold standard therapy for metastatic prostate cancer since 2010, represents one of the main factors responsible for the failure of prostate cancer therapy. According to the present knowledge, different processes contribute to the appearance of docetaxel resistance and non-coding RNA seems to play a relevant role in them. In this review, a comprehensive overview of the miRNA network involved in docetaxel resistance is described, highlighting the pathway/s affected by their activity.

Hydroxychloroquine Blocks Autophagy and Promotes Apoptosis of the Prostate after Castration in Rats

Autophagy is an important pro-survival mechanism and closely related to apoptosis. The aim of this study was to investigate whether hydroxychloroquine (HCQ) blocks autophagy and promotes apoptosis of the prostate after castration.

METHODS

Thirty-six male SD rats were randomly divided into 3 groups (n = 12): control group (sham operation), castration group, and HCQ group (castrated and treated with HCQ). On day 7, all mice were executed and prostates were isolated. The morphological changes of prostates were observed by light microscope, and the ultrastructure changes were observed under scanning electron microscope (SEM). The protein expression of Beclin-l, P62, caspase-3, Bcl-2, and Bax was assessed by immunohistochemical analyses. The mRNA expression of microtubule-associated protein light chain 3 (LC3) and autophagy-related gene 5 (Atg5) was detected by RT-PCR.

RESULTS

Prostates of castration group shrank remarkably and prostates of HCQ group shrank more remarkably than castration group. Cytolysosomes were visible in the prostates of the castration group under SEM. Immunohistochemistry showed that the protein of Beclin-1 increased in the castration group compared to the control group, while decreased in the HCQ group compared to the castration group. While P62 protein moderately dyed in the control group and weakly dyed in the castration group, it strongly dyed in the HCQ group. Caspase-3 and Bax protein were weakly dyed in the control group but moderately dyed in the castration group and strongly dyed in the HCQ group. The expressions of apoptosis suppressor Bcl-2 were reduced in the castration group and further reduced in the HCQ group compared to the castration group. RT-PCR revealed that the mRNA of LC3 and Atg5 in the castration group increased compared to the control group, while decreased after treated with HCQ.

CONCLUSION

Autophagy increased after castrated in prostates, while decreased after treated with HCQ; all these indicated that HCQ blocked autophagy and then promoted prostate apoptosis of castrated mice.

circCRKL suppresses the progression of prostate cancer cells by regulating the miR-141/KLF5 axis

BACKGROUND

Prostate cancer (PCa) is a prevalent human malignancy in males. Circular RNA circCRKL (Hsa_circ_0001206) was reported to be lowly expressed in PCa tissues. However, the regulatory role of circCRKL in PCa is poorly defined.

METHODS

Levels of circCRKL, microRNA-141 (miR-141), and Kruppel-like factor (KLF5) were measured by real-time quantitative polymerase chain reaction (RT-qPCR). Cell cycle progression, apoptosis, migration, and invasion were examined by Flow cytometry, Wound healing, and transwell assays. The underlying relationship between miR-141 and circCRKL or KLF5 was predicted by starBase, and then verified by a dual-luciferase reporter, RNA Immunoprecipitation (RIP), and RNA pull-down assays. The protein level of KLF5 was assessed by western blot assay. The biological role of circCRKL was detected by a xenograft tumor model in vivo.

RESULTS

CircCRKL and KLF5 were decreased, and miR-141 was increased in PCa tissues and cells. The functional analysis discovered that the overexpression of circCRKL repressed cell cycle progression, migration, invasion, and boosted apoptosis of PCa cells. Mechanically, circCRKL could positively regulate KLF5 expression by sponging miR-141. In addition, circCRKL upregulation could hinder PCa tumor growth in vivo.

CONCLUSION

These findings revealed that circCRKL inhibited the progression of PCa through upregulating KLF5 expression by sponging miR-141, elucidating a novel regulatory pathway in PCa cells. Our research suggested an underlying circRNA-targeted therapy for PCa.

BDH2 triggers ROS-induced cell death and autophagy by promoting Nrf2 ubiquitination in gastric cancer

Background

3-Hydroxy butyrate dehydrogenase 2 (BDH2) is a short-chain dehydrogenase/reductase family member that plays a key role in the development and pathogenesis of human cancers. However, the role of BDH2 in gastric cancer (GC) remains largely unclear. Our study aimed to ascertain the regulatory mechanisms of BDH2 in GC, which could be used to develop new therapeutic strategies.

Methods

Western blotting, immunohistochemistry, and RT-PCR were used to investigate the expression of BDH2 in GC specimens and cell lines. Its correlation with the clinicopathological characteristics and prognosis of GC patients was analysed. Functional assays, such as CCK-8 and TUNEL assays, transmission electron microscopy, and an in vivo tumour growth assay, were performed to examine the proliferation, apoptosis, and autophagy of GC cells. Related molecular mechanisms were clarified by luciferase reporter, coimmunoprecipitation, and ubiquitination assays.

Results

BDH2 was markedly downregulated in GC tissues and cells, and the low expression of BDH2 was associated with poor survival of GC patients. Functionally, BDH2 overexpression significantly induced apoptosis and autophagy in vitro and in vivo. Mechanistically, BDH2 promoted Keap1 interaction with Nrf2 to increase the ubiquitination level of Nrf2. Ubiquitination/degradation of Nrf2 inhibited the activity of ARE to increase accumulation of reactive oxygen species (ROS), thereby inhibiting the phosphorylation levels of Akt^Ser473 and mTOR^Ser2448.

Conclusions

Our study indicates that BDH2 is an important tumour suppressor in GC. BDH2 regulates intracellular ROS levels to mediate the PI3K/Akt/mTOR pathway through Keap1/Nrf2/ARE signalling, thereby inhibiting the growth of GC.

TGF-β causes Docetaxel resistance in Prostate Cancer via the induction of Bcl-2 by acetylated KLF5 and Protein Stabilization

Prostate cancer is the second leading cause of cancer-related death in the United States. As a first line treatment for hormone-refractory prostate cancer, docetaxel (DTX) treatment leads to suboptimal effect since almost all patients eventually develop DTX resistance. In this study, we investigated whether and how TGF-β affects DTX resistance of prostate cancer.

Methods: Cytotoxicity of DTX in DU 145 and PC-3 cells was measured by CCK-8 and Matrigel colony formation assays. Resistance to DTX in DU 145 cells was examined in a xenograft tumorigenesis model. A luciferase reporter system was used to determine transcriptional activities. Gene expression was analyzed by RT-qPCR and Western blotting.

Results: We found that KLF5 is indispensable in TGF-β-induced DTX resistance. Moreover, KLF5 acetylation at lysine 369 mediates DTX resistance in vitro and in vivo. We showed that the TGF-β/acetylated KLF5 signaling axis activates Bcl-2 expression transcriptionally. Furthermore, DTX-induced Bcl-2 degradation depends on a proteasome pathway, and TGF-β inhibits DTX-induced Bcl-2 ubiquitination.

Conclusion: Our study demonstrated that the TGF-β-acetylated KLF5-Bcl-2 signaling axis mediates DTX resistance in prostate cancer and blockade of this pathway could provide clinical insights into chemoresistance of prostate cancer.

Downregulation of Collagen COL4A6 Is Associated with Prostate Cancer Progression and Metastasis

Aims: To determine the association between collagen type IV alpha 6 (COL4A6) expression levels and prostate cancer invasion and metastasis. Methods: We analyzed three Gene Expression Omnibus (GEO) datasets through the GEO2R online tool to obtain the set of differentially expressed genes (DEGs) between malignant and nonmalignant prostate tissues, and further analyzed the COL4A6 gene's expression in databases. Western blot assays, real-time quantitative polymerase chain reaction analysis, and immunofluorescence staining were used to detect COL4A6 gene expression. Wound healing assays and cell invasion transwell assays were performed to measure cell invasion and siRNA was used to knock down COL4A6 gene expression. Results: Through the use of bioinformatic tools we showed that the COL4A6 gene is one of the highly downregulated genes in prostate cancer; additionally, hypermethylation of the COL4A6 promoter in prostate cancer is correlated with lower expression levels. We also showed that downregulation of COL4A6, which activates the p-FAK/MMP-9 signaling pathway in prostate cancer cells, is associated with prostate cancer cell metastasis based on data retrieved from The Cancer Genome Atlas (TCGA) and GEO databases. Finally, we found that the COL4A6 protein is localized extracellularly and its expression is positively correlated with disease-free survival of prostate cancer patients. Conclusion: Our results indicate that downregulation of COL4A6 may promote prostate cancer progression and invasion. Additionally, COL4A6 and its promoter methylation status could be valuable markers for prostate cancer prognoses.

KLF5 inhibits STAT3 activity and tumor metastasis in prostate cancer by suppressing IGF1 transcription cooperatively with HDAC1

KLF5 is frequently deleted and downregulated in prostate cancer, and recently it has been reported that KLF5 loss is enriched in the aggressive branches of prostate cancer evolution. However, why KLF5 loss is associated with prostate cancer aggressiveness is still not clear. Herein, we analyzed KLF5 expression in TCGA and GEO database, as well as prostate cancer tissue microarray, and found that KLF5 expression significantly decreased in prostate cancer accompanying with tumor progression; moreover, KLF5 downregulation was associated with shorter survival of patients. Interestingly, we also found that KLF5 expression was obviously lower in prostate cancer metastases than in localized tissues, indicating that KLF5 downregulation is associated with prostate cancer invasion and metastasis. To assess this effect of KLF5, we knocked down KLF5 in prostate cancer cells and found that KLF5 knockdown promoted invasive ability of prostate cancer cells in vitro and in vivo. Moreover, we found that KLF5 downregulation enhanced the expression of IGF1 and STAT3 phosphorylation, while block of IGF1 with antibody decreased the enhancement of STAT3 activity and prostate cancer cell invasive ability by KLF5 knockdown, indicating that KLF5 inhibits prostate cancer invasion through suppressing IGF1/STAT3 pathway. Mechanistically, we found that KLF5 interacted with deacetylase HDAC1 and KLF5 is necessary for the binding of HDAC1 on IGF1 promoter to suppress IGF1 transcription. Taken together, our results indicate that KLF5 could be an important suppressor of prostate cancer invasion and metastasis, because KLF5 could suppress the transcription of IGF1, a tumor cell autocrine cytokine, and its downstream cell signaling to inhibit cell invasive ability, and reveal a novel mechanism for STAT3 activation in prostate cancer. These findings may provide evidence for the precision medicine in prostate cancer.

The beclin 1 interactome: Modification and roles in the pathology of autophagy-related disorders

Beclin 1 a yeast Atg6/VPS30 orthologue has a significant role in autophagy process (Macroautophagy) and protein sorting. The function of beclin 1 depends on the interaction with several autophagy-related genes (Atgs) and other proteins during the autophagy process. The role mediated by beclin 1 is controlled by various conditions and factors. Beclin 1 is regulated at the gene and protein levels by different factors. These regulations could subsequently alter the beclin 1 induced autophagy process. Therefore, it is important to study the components of beclin 1 interactome and factors affecting its expression. Expression of this gene is differentially regulated under different conditions in different cells or tissues. So, the regulation part is important to study as beclin 1 is one of the candidate genes involved in diseases related to autophagy dysfunction. This review focuses on the functions of beclin 1, its interacting partners, regulations at gene and protein level, and the role of beclin 1 interactome in relation to various diseases along with the recent developments in the field.

Targeting GRP78-dependent AR-V7 protein degradation overcomes castration-resistance in prostate cancer therapy

Rationale: Androgen receptor splice variant 7 (AR-V7) is a leading cause of the development of castration-resistant prostate cancer (CRPC). However, the regulation and function of AR-V7 at levels of post-translational modifications in prostate cancer therapy remain poorly understood. Here, we conducted a library screen of natural products to identify potential small molecules responsible for AR-V7 protein degradation in human prostate cancer cell lines.

Methods: A natural product library was used to screen the inhibitor of AR-V7. Co-IP and biomass spectrum assays were used to identify the AR-V7-interacting proteins, whereas western blot, confocal microscopy, RNA interfering, and gene transfection were used to validate these interactions. Cell viability, EDU staining, and colony formation assays were employed to detect cell growth and proliferation. Flowcytometry assays were used to detect the distribution of cell cycle. Mouse xenograft models were used to study the anti-CRPC effects in vivo.

Results: This screen identified rutaecarpine, one of the major components of the Chinese medicine Evodia rutaecarpa, as a novel chemical that selectively induces AR-V7 protein degradation via K48-linked ubiquitination. Mechanically, this effect relies on rutaecarpine inducing the formation of a GRP78-AR-V7 protein complex, which further recruits the E3 ligase SIAH2 to directly promote the ubiquitination of AR-V7. Consequently, the genetic and pharmacological activation of the GRP78-dependent AR-V7 protein degradation restores the sensitivity of castration-resistant prostate cancer to anti-androgen therapy in cell culture and animal models.

Conclusions: These findings not only provide a new approach for overcoming castration-resistance in prostate cancer therapy, but also increase our understanding about the interplay between molecular chaperones and ubiquitin ligase in shaping protein stability.

FOXM1 contributes to docetaxel resistance in castration-resistant prostate cancer by inducing AMPK/mTOR-mediated autophagy

Docetaxel-mediated chemotherapy is the first line therapy for metastatic castration-resistant prostate cancer (CRPC) patients, but its therapeutic benefit is limited by the development of resistance. Although Forkhead box protein M1 (FOXM1) has been implicated in prostate tumorigenesis and metastasis, its role in docetaxel resistance has not been studied. Here, we showed that FOXM1 expression was upregulated in the docetaxel resistant CRPC cell lines (PC3-DR and VCaP-DR) and knockdown of FOXM1 sensitized the cells to docetaxel both in vitro and in vivo. In addition, autophagy was found to be significantly enhanced in resistant cells. Moreover, FOXM1 overexpression cells showed increased autophagic flux and higher numbers of autophagosomes. Knockdown of ATG7, beclin-1 or cotreatment with chloroquine, partly restored sensitivity to docetaxel in the FOXM1-overexpressing cells. Mechanistically, FOXM1 targeted AMPK/mTOR to activate the autophagy pathway and altered docetaxel response in CRPC. These findings identify the role of FOXM1 as well as the mechanism underlying FOXM1 action in docetaxel sensitivity and may, therefore, aid in design of CRPC therapies.