Src Inhibition Can Synergize with Gemcitabine and Reverse Resistance in Triple Negative Breast Cancer Cells via the AKT/c-Jun Pathway

Small Molecule Therapeutics in the Pipeline Targeting for Triple-Negative Breast Cancer: Origin, Challenges, Opportunities, and Mechanisms of Action

Triple-negative breast cancer (TNBC) cells are devoid of estrogen receptors (ERs), progesterone receptor (PRs), and human epidermal growth factor receptor 2 (HER2), and it (TNBC) counts for about 10-15% of all breast cancers. TNBC is highly invasive, having a faster growth rate and a higher risk of metastasis and recurrence. Still, chemotherapy is one of the widely used options for treating TNBC. This study reviewed the histological and molecular characterization of TNBC subtypes, signaling pathways that are aberrantly expressed, and small molecules targeting these pathways, as either single agents or in combination with other therapeutic agents like chemotherapeutics, immunotherapeutics, and antibody-drug conjugates; their mechanisms of action, challenges, and future perspectives were also reviewed. A detailed analytical review was carried out using the literature collected from the SciFinder, PubMed, ScienceDirect, Google Scholar, ACS, Springer, and Wiley databases. Several small molecule inhibitors were found to be therapeutics for treating TNBC. The mechanism of action and the different signaling pathways through which the small molecules exert their effects were studied, including clinical trials, if reported. These small molecule inhibitors include buparlisib, everolimus, vandetanib, apatinib, olaparib, salidroside, etc. Some of the signaling pathways involved in TNBC, including the VEGF, PARP, STAT3, MAPK, EGFR, P13K, and SRC pathways, were discussed. Due to the absence of these biomarkers, drug development for treating TNBC is challenging, with chemotherapy being the main therapeutic agent. However, chemotherapy is associated with chemoresistance and a high toxicity to healthy cells as side effects. Hence, there is a continuous demand for small-molecule inhibitors that specifically target several signaling pathways that are abnormally expressed in TNBC. We attempted to include all the recent developments in this field. Any omission is truly unintentional.

The impact of paternal age on cumulative assisted reproductive technology outcomes

Objective

To investigate the impact of paternal age on cumulative live birth rate in ART.

Design

Retrospective single-center cohort study.

Patients

All female patients aged 18-43 years and male patients aged 18-60 years, who performed their first ART cycle between January 2018 and December 2020, were included.

Main outcome measures

The primary outcome, cumulative live birth rate (cLBR), was estimated following fresh or frozen embryo transfers issued from an ART cycle. Secondary outcomes included the cumulative pregnancy rate (cPR) and miscarriage rate. Subgroup analyzes were performed as follows: men <45 and ≥ 45; female <35, 35-38, and > 38 years.

Results

A total of 2,358 couples were included in this study. The sperm quantity of male patients within both age groups was divided in two groups: normal and abnormal, which were found to be in significantly equal proportions. There were significantly fewer current smokers in the male group ≥45. The cPR was 0.5301 in the group <45 and 0.3111 in the group ≥45, with a p-value <0.001. Analysis according to the female age revealed that, in the female group >38, the cLBR rate was 0.26 for men <45 and 0.19 for men ≥45, with a p-value of 0.061. Additionally, the cPR was 0.34 in the male group <45 and 0.21 in the group ≥45, with a p-value <0.001. In the female group between 35 and 38 years of age, the cLBR was 0.44 in the male group <45 and 0.3 in the male group ≥45, with a p-value of 0.031. The cPR was 0.49 in the male group <45 and 0.34 in the group ≥45, p = 0.036. Within the female group <35, we observed non-significant results. The miscarriage rate results were not significantly different for women ≤38.

Conclusion

According to the results from our study, male age ≥ 45 has a significant impact on cumulative ART outcomes.

Challenges and Opportunities in Developing Targeted Therapies for Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is a heterogeneous group of breast cancers characterized by their lack of estrogen receptors, progesterone receptors, and the HER2 receptor. They are more aggressive than other breast cancer subtypes, with a higher mean tumor size, higher tumor grade, the worst five-year overall survival, and the highest rates of recurrence and metastasis. Developing targeted therapies for TNBC has been a major challenge due to its heterogeneity, and its treatment still largely relies on surgery, radiation therapy, and chemotherapy. In this review article, we review the efforts in developing targeted therapies for TNBC, discuss insights gained from these efforts, and highlight potential opportunities going forward. Accumulating evidence supports TNBCs as multi-driver cancers, in which multiple oncogenic drivers promote cell proliferation and survival. In such multi-driver cancers, targeted therapies would require drug combinations that simultaneously block multiple oncogenic drivers. A strategy designed to generate mechanism-based combination targeted therapies for TNBC is discussed.

Deciphering Common Traits of Breast and Ovarian Cancer Stem Cells and Possible Therapeutic Approaches

Breast cancer (BC) and ovarian cancer (OC) are among the most common and deadly cancers affecting women worldwide. Both are complex diseases with marked heterogeneity. Despite the induction of screening programs that increase the frequency of earlier diagnosis of BC, at a stage when the cancer is more likely to respond to therapy, which does not exist for OC, more than 50% of both cancers are diagnosed at an advanced stage. Initial therapy can put the cancer into remission. However, recurrences occur frequently in both BC and OC, which are highly cancer-subtype dependent. Therapy resistance is mainly attributed to a rare subpopulation of cells, named cancer stem cells (CSC) or tumor-initiating cells, as they are capable of self-renewal, tumor initiation, and regrowth of tumor bulk. In this review, we will discuss the distinctive markers and signaling pathways that characterize CSC, their interactions with the tumor microenvironment, and the strategies they employ to evade immune surveillance. Our focus will be on identifying the common features of breast cancer stem cells (BCSC) and ovarian cancer stem cells (OCSC) and suggesting potential therapeutic approaches.

Prognostic value of fibrinogen to albumin ratios among critically ill patients with acute kidney injury

Fibrinogen to albumin ratios (FAR) have shown to be a promising prognostic factor for improving the predictive accuracy in various diseases. This study explores FAR's prognostic significance in critically ill patients with acute kidney injury (AKI). All clinical data were extracted from the Multiparameter Intelligent Monitoring in Intensive Care Database III version 1.4. All patients were divided into four groups based on FAR quartiles. The primary endpoint was in-hospital mortality. A generalized additive model was applied to explore a nonlinear association between FAR and in-hospital mortality. The Cox proportional hazards models were used to determine the association between FAR and in-hospital mortality. A total of 5001 eligible subjects were enrolled. Multivariate analysis demonstrated that higher FAR was an independent predictor of in-hospital mortality after adjusting for potential confounders (HR, 95% CI 1.23, 1.03-1.48, P = 0.025). A nonlinear relationship between FAR and in-hospital mortality was observed. FAR may serve as a potential prognostic biomarker in critically patients with AKI and higher FAR was associated with increased risk of in-hospital mortality among these patients.

Global Exploration of RNA-Binding Proteins in Exercise-Induced Adult Hippocampal Neurogenesis: A Transcriptome Meta-analysis and Computational Study

Voluntary physical exercise is a robust enhancer of adult hippocampal neurogenesis (AHN). A complete understanding of the molecular regulation of AHN is important in order to exploit the benefits of the process toward therapeutic approaches. Several factors such as epigenetic modifiers, non-coding RNAs, and transcription factors have been reported to regulate AHN. However, there is a limited understanding of the impact of RNA-binding proteins (RBPs) on exercise-mediated AHN, in spite of their well-documented significance in embryonic neurogenesis. The present study is the first global analysis to catalog the potential RBPs influencing exercise-mediated AHN. Here, a transcriptome meta-analysis was conducted to study exercise-mediated gene expression modulation in hippocampi of adult mice. Next, potential RBPs influencing transcriptome-wide expression changes via untranslated regions (UTRs) were identified. Among other RBPs, MATR3, Musashi, TIA1, and FXR2 (known critical modulators of neurogenesis) were found to potentially regulate gene expression patterns. Subsequently, binding sites of known neurogenesis-regulating RBPs were identified in the UTRs of AHN-associated genes modulated by exercise. Finally, a number of RBPs including RBFOX1, RBFOX3, and QKI (known regulators of neurogenesis) were found to be highly expressed in mouse hippocampal formation and also potentially interact with other RBPs, suggesting their combinatorial functioning in exercise-induced AHN. Thus, the present meta-analysis-based computational study identified several RBPs potentially important in exercise-induced AHN, which could form a foundation for further experiments to unravel RBP-mediated regulation of AHN.

Korean red ginseng water extract inhibits cadmium-induced lung injury via suppressing MAPK/ERK1/2/AP-1 pathway

Background

Few studies reported the therapeutic effect of Korean Red Ginseng (KRG) in lung inflammatory diseases. However, the anti-inflammatory role and underlying molecular in cadmium-induced lung injury have been poorly understood, directly linked to chronic lung diseases (CLDs): chronic obstructive pulmonary disease (COPD), cancer etc. Therefore, in this study we aim to investigate the therapeutic activities of water extract of KRG (KRG-WE) in mouse cadmium-induced lung injury model.

Method

The anti-inflammatory roles and underlying mechanisms of KRG-WE were evaluated in vitro under cadmium-stimulated lung epithelial cells (A549) and HEK293T cell line and in vivo in cadmium-induced lung injury mouse model using semi-quantitative polymerase chain reaction (RT-PCR), quantitative real-time PCR (qPCR), luciferase assay, immunoblotting, and FACS.

Results

KRG-WE strongly ameliorated the symptoms of CdSO₄-induced lung injury in mice according to total cell number in bronchoalveolar lavage fluid (BALF) and severity scores as well as cytokine levels. KRG-WE significantly suppressed the upregulation of inflammatory signaling comprising mitogen-activated protein kinases (MAPK) and their upstream enzymes. In in vitro study, KRG-WE suppressed expression of interleukin (IL)-6, matrix metalloproteinase (MMP)-2, and IL-8 while promoting recovery in CdSO₄-treated A549 cells. Similarly, KRG-WE reduced phosphorylation of MAPK and c-Jun/c-Fos in cadmium-exposed A549 cells.

Conclusion

KRG-WE was found to attenuate symptoms of cadmium-induced lung injury and reduce the expression of inflammatory genes by suppression of MAPK/AP-1-mediated pathway.

lncRNA RP11-147L13.8 suppresses metastasis and chemo-resistance by modulating the phosphorylation of c-Jun protein in GBC

Long non-coding RNAs (lncRNAs) have been identified as critical contributors in tumor progression for many types of cancer. However, their functions in gallbladder cancer (GBC) have not been systematically clarified. In this study, the clinical significance, biological function, and underlying mechanism of lncRNA RP11-147L13.8 in GBC were investigated. The quantitative real-time PCR result indicated that lncRNA RP11-147L13.8 was found to be recurrently downregulated in GBC tumor samples. Kaplan-Meier analysis revealed that decreased lncRNA RP11-147L13.8 expression level was associated with poor survival of GBC patients (p = 0.025). Then, both in vitro and in vivo experiments elucidated that the overexpression of lncRNA RP11-147L13.8 suppressed the migration and invasion abilities of GBC cells and promoted the sensitivity to gemcitabine of GBC cells. Furthermore, we found that lncRNA RP11-147L13.8 physically interacted with c-Jun protein and decreased the phosphorylation on serine-73 (c-Jun-Ser73), which might cause the enhancement of the migration, invasion, and sensitivity to gemcitabine of GBC tumor cells. In conclusion, our study identified lncRNA RP11-147L13.8 as a promising prognostic indicator for patients with GBC, providing insights into the molecular pathogenesis of GBC. lncRNA RP11-147L13.8 is a potential therapeutic combination for gemcitabine in GBC treatment.

Modified Gold Nanoparticles to Overcome the Chemoresistance to Gemcitabine in Mutant p53 Cancer Cells

Mutant p53 proteins result from missense mutations in the TP53 gene, the most mutated in human cancer, and have been described to contribute to cancer initiation and progression. Therapeutic strategies for targeting mutant p53 proteins in cancer cells are limited and have proved unsuitable for clinical application due to problems related to drug delivery and toxicity to healthy tissues. Therefore, the discovery of efficient and safe therapeutic strategies that specifically target mutant p53 remains challenging. In this study, we generated gold nanoparticles (AuNPs) chemically modified with low molecular branched polyethylenimine (bPEI) for the efficient delivery of gapmers targeting p53 mutant protein. The AuNPs formulation consists of a combination of polymeric mixed layer of polyethylene glycol (PEG) and PEI, and layer-by-layer assembly of bPEI through a sensitive linker. These nanoparticles can bind oligonucleotides through electrostatic interactions and release them in the presence of a reducing agent as glutathione. The nanostructures generated here provide a non-toxic and powerful system for the delivery of gapmers in cancer cells, which significantly downregulated mutant p53 proteins and altered molecular markers related to cell growth and apoptosis, thus overcoming chemoresistance to gemcitabine.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

Caragana rosea Turcz Methanol Extract Inhibits Lipopolysaccharide-Induced Inflammatory Responses by Suppressing the TLR4/NF-κB/IRF3 Signaling Pathways

Caragana rosea Turcz, which belongs to the Leguminosae family, is a small shrub found in Northern and Eastern China that is known to possess anti-inflammatory properties and is used to treat fever, asthma, and cough. However, the underlying molecular mechanisms of its anti-inflammatory effects are unknown. Therefore, we used lipopolysaccharide (LPS) in RAW264.7 macrophages to investigate the molecular mechanisms that underlie the anti-inflammatory activities of a methanol extract of Caragana rosea (Cr-ME). We showed that Cr-ME reduced the production of nitric oxide (NO) and mRNA levels of iNOS, TNF-α, and IL-6 in a concentration-dependent manner. We also found that Cr-ME blocked MyD88- and TBK1-induced NF-κB and IRF3 promoter activity, suggesting that it affects multiple targets. Moreover, Cr-ME reduced the phosphorylation levels of IκBα, IKKα/β and IRF3 in a time-dependent manner and regulated the upstream NF-κB proteins Syk and Src, and the IRF3 protein TBK1. Upon overexpression of Src and TBK1, Cr-ME stimulation attenuated the phosphorylation of the NF-κB subunits p50 and p65 and IRF3 signaling. Together, our results suggest that the anti-inflammatory activity of Cr-ME occurs by inhibiting the NF-κB and IRF3 signaling pathways.

Chemoresistance in breast cancer: PI3K/Akt pathway inhibitors vs the current chemotherapy

Breast cancer is the most prevalent type of cancer among women. Several types of drugs, targeting the specific proteins expressed on the breast cancer cell surface (such as receptor tyrosine kinases and immune checkpoint regulators) and proteins involved in cell cycle and motility (including cyclin-dependent kinases, DNA stabilisers, and cytoskeleton modulators) are approved for different subtypes of breast cancer. However, breast cancer also has a poor response to conventional chemotherapy due to intrinsic and acquired resistance, and an Akt fingerprint is detectable in most drug-resistant cases. Overactivation of Akt and its upstream and downstream regulators in resistant breast cancer cells is considered a major potential target for novel anti-cancer therapies, suggesting that Akt signalling acts as a cellular mechanism against chemotherapy. The present review has shown that sustained activation of Akt results in resistance to different types of chemotherapy. Akt signalling plays a cellular defence role against chemotherapy and (1) enhances multi-drug resistance, (2) increases reactive oxygen species at breast tumor microenvironment, (3) enhances anaerobic metabolism, (4) inhibits the tricarboxylic cycle, (5) promotes PD-L1 upregulation, (6) inhibits apoptosis, (7) increases glucose uptake, and more importantly (8) recruits and interconnects the plasma membrane, nucleus, endoplasmic reticulum, and mitochondria to hijack breast cancer cells and rescue these cells from chemotherapy. Therefore, Akt signalling is considered a cellular defence mechanism employed against chemotherapeutic effects. In addition, interfering roles of PI3K/Akt signalling on the current cytotoxic and molecularly targeted therapy as well as immunotherapy of breast cancer are discussed with a clinical approach. Although, alpelisib, a PIK3CA inhibitor, is the only PI3K/Akt pathway inhibitor approved for breast cancer, we also highlight well-evaluated inhibitors of PI3K/Akt signalling based on different subtypes of breast cancer, which are under clinical trials whether as monotherapy or in combination with other types of chemotherapy.

Combinatorial Strategies to Target Molecular and Signaling Pathways to Disarm Cancer Stem Cells

Cancer is an urgent public health issue with a very huge number of cases all over the world expected to increase by 2040. Despite improved diagnosis and therapeutic protocols, it remains the main leading cause of death in the world. Cancer stem cells (CSCs) constitute a tumor subpopulation defined by ability to self-renewal and to generate the heterogeneous and differentiated cell lineages that form the tumor bulk. These cells represent a major concern in cancer treatment due to resistance to conventional protocols of radiotherapy, chemotherapy and molecular targeted therapy. In fact, although partial or complete tumor regression can be achieved in patients, these responses are often followed by cancer relapse due to the expansion of CSCs population. The aberrant activation of developmental and oncogenic signaling pathways plays a relevant role in promoting CSCs therapy resistance. Although several targeted approaches relying on monotherapy have been developed to affect these pathways, they have shown limited efficacy. Therefore, an urgent need to design alternative combinatorial strategies to replace conventional regimens exists. This review summarizes the preclinical studies which provide a proof of concept of therapeutic efficacy of combinatorial approaches targeting the CSCs.

Translating GWAS-identified loci for cardiac rhythm and rate using an in vivo image- and CRISPR/Cas9-based approach

A meta-analysis of genome-wide association studies (GWAS) identified eight loci that are associated with heart rate variability (HRV), but candidate genes in these loci remain uncharacterized. We developed an image- and CRISPR/Cas9-based pipeline to systematically characterize candidate genes for HRV in live zebrafish embryos. Nine zebrafish orthologues of six human candidate genes were targeted simultaneously in eggs from fish that transgenically express GFP on smooth muscle cells (Tg[acta2:GFP]), to visualize the beating heart. An automated analysis of repeated 30 s recordings of beating atria in 381 live, intact zebrafish embryos at 2 and 5 days post-fertilization highlighted genes that influence HRV (hcn4 and si:dkey-65j6.2 [KIAA1755]); heart rate (rgs6 and hcn4); and the risk of sinoatrial pauses and arrests (hcn4). Exposure to 10 or 25 µM ivabradine—an open channel blocker of HCNs—for 24 h resulted in a dose-dependent higher HRV and lower heart rate at 5 days post-fertilization. Hence, our screen confirmed the role of established genes for heart rate and rhythm (RGS6 and HCN4); showed that ivabradine reduces heart rate and increases HRV in zebrafish embryos, as it does in humans; and highlighted a novel gene that plays a role in HRV (KIAA1755).

Structure and Characterization of a Covalent Inhibitor of Src Kinase

Unregulated Src activity promotes malignant processes in cancer, but no Src-directed targeted therapies are used clinically, possibly because early Src inhibitors produce off-target effects leading to toxicity. Improved selective Src inhibitors may enable Src-directed therapies. Previously, we reported an irreversible Src inhibitor, DGY-06-116, based on the hybridization of dasatinib and a promiscuous covalent kinase probe SM1-71. Here, we report biochemical and biophysical characterization of this compound. An x-ray co-crystal structure of DGY-06-116: Src shows a covalent interaction with the kinase p-loop and occupancy of the back hydrophobic kinase pocket, explaining its high potency, and selectivity. However, a reversible analog also shows similar potency. Kinetic analysis shows a slow inactivation rate compared to other clinically approved covalent kinase inhibitors, consistent with a need for p-loop movement prior to covalent bond formation. Overall, these results suggest that a strong reversible interaction is required to allow sufficient time for the covalent reaction to occur. Further optimization of the covalent linker may improve the kinetics of covalent bond formation.

Molecular determinants of drug response in TNBC cell lines

PURPOSE

There is a need for biomarkers of drug efficacy for targeted therapies in triple-negative breast cancer (TNBC). As a step toward this, we identify multi-omic molecular determinants of anti-TNBC efficacy in cell lines for a panel of oncology drugs.

METHODS

Using 23 TNBC cell lines, drug sensitivity scores (DSS3) were determined using a panel of investigational drugs and drugs approved for other indications. Molecular readouts were generated for each cell line using RNA sequencing, RNA targeted panels, DNA sequencing, and functional proteomics. DSS3 values were correlated with molecular readouts using a FDR-corrected significance cutoff of p* < 0.05 and yielded molecular determinant panels that predict anti-TNBC efficacy.

RESULTS

Six molecular determinant panels were obtained from 12 drugs we prioritized based on their efficacy. Determinant panels were largely devoid of DNA mutations of the targeted pathway. Molecular determinants were obtained by correlating DSS3 with molecular readouts. We found that co-inhibiting molecular correlate pathways leads to robust synergy across many cell lines.

CONCLUSIONS

These findings demonstrate an integrated method to identify biomarkers of drug efficacy in TNBC where DNA predictions correlate poorly with drug response. Our work outlines a framework for the identification of novel molecular determinants and optimal companion drugs for combination therapy based on these correlates.

miR-205-5p downregulation decreases gemcitabine sensitivity of breast cancer cells via ERp29 upregulation

Breast cancer is the most common cancer in women worldwide, and the incidence and mortality rates are increasing every year. Dysregulation of microRNAs (miRNAs or miRs) is an important step in the initiation and development of breast cancer. Previous studies demonstrated that miR-205-5p is closely associated with occurrence and development of breast cancer; however, underlying mechanisms remain unclear. In the present study, reverse transcription-quantitative polymerase chain reaction assays were used to analyze miR-195-5p and endoplasmic reticulum protein 29 (ERp29) levels in breast cancer and matched normal tissues. Western blot analysis was performed to analyze ERp29 and heat shock protein 27 (HSP27) protein expression levels. Cell viability, flow cytometry and luciferase reporter assay were used to examine cell proliferation, apoptosis and direct miRNA-mRNA binding, respectively. The results revealed that miR-205-5p expression in breast cancer tissues and cell lines was decreased compared with normal tissues and a normal cell line. Overexpression of miR-205-5p significantly augmented cytotoxicity effects of gemcitabine treatment in MDA-MB-231 and BT549 cells. It was observed that miR-205-5p negatively regulated ERp29 expression in breast cancer cells. Dual luciferase assays confirmed that ERp29 was a target of miR-205-5p in breast cancer cells. Additionally, following the established gemcitabine-resistant MDA-MB-231 cells (MDA-MB-231/GEM), ERp29 and HSP27 expression was upregulated and miR-205-5p was downregulated compared with parental cells. Overexpression of miR-205-5p reversed gemcitabine resistance in MDA-MB-231/GEM cells. In conclusion, the present study indicated that miR-205-5p may inhibit gemcitabine resistance in breast cancer cells via inhibition of ERp29 expression.

Overexpression of microRNA-620 facilitates the resistance of triple negative breast cancer cells to gemcitabine treatment by targeting DCTD

Patients with triple negative breast cancer (TNBC) have a poor survival rate following chemotherapy due to drug resistance. Notably, the molecular mechanism of drug resistance remains elusive. Between December 2011 and December 2014, 36 TNBC samples were obtained from Liaocheng People's Hospital. Three gemcitabine-resistant MDA-MB-231 cell lines (MDA-MB-231rGEM1, MDA-MB-231rGEM2 and MDA-MB-231rGEM3) were obtained by exposure of MDA-MB-231 cells to increasing concentrations of gemcitabine for >12 months. Reverse transcription-quantitative polymerase chain reaction was performed to detect the expression levels of specific genes, including microRNA (miR)-620, ATP-binding cassette sub-family B member 1 (ABCB1), ABCC10, cytidine monophosphate kinase, deoxycytidine monophosphate deaminase (DCTD), nucleoside diphosphate kinase 1 (NME1), ribonucleoside-diphosphate reductase large subunit (RRM1) and RRMB2. Western blot analysis was performed to assess the protein expression levels of DCTD. Furthermore, cell proliferation was assessed using a Cell Counting Kit-8 assay and cell apoptosis was detected using an Annexin V/Dead Cell Apoptosis kit. Interactions between miR-620 and DCTD were predicted using TargetScan and detected with the dual luciferase reporter assay. Elevation of miR-620 expression levels were detected in two of the assessed gemcitabine-resistant MDA-MB-231 cell lines compared with MDA-MB-231 cells. Gemcitabine induced significant elevation of miR-620 in MDA-MB-231 cells. An increase of DCTD at mRNA and protein expression levels in MDA-MB-231rGEM1 cells was observed compared with those in MDA-MB-231 cells. Results suggested that DCTD was directly regulated by miR-620. Inhibition of miR-620 and overexpression of DCTD reversed gemcitabine resistance in MDA-MB-231rGEM1 cells via inducing cell apoptosis and cell growth arrest. A negative correlation was identified between miR-620 and DCTD mRNA expression levels in patients with TNBC. The present results demonstrated that overexpression of miR-620 could contribute to the development of gemcitabine resistance in patients with TNBC via the direct downregulation of DCTD.

Rack1 mediates Src binding to drug transporter P-glycoprotein and modulates its activity through regulating Caveolin-1 phosphorylation in breast cancer cells

The failure of chemotherapy and the emergence of multidrug resistance (MDR) are the major obstacles for effective therapy in locally advanced and metastatic breast cancer. Overexpression of the drug transporter P-glycoprotein (P-gp) in cancer cells is one of the main causes of MDR due to its ability to efflux anticancer drugs out of cells. Although the signaling node that regulates the expression of P-gp has been intensively investigated; the regulatory mechanism underlying P-gp transport activity remains obscure. Herein, we reported that Rack1 and tyrosine kinase Src confer drug resistance through modulating the transport function of P-gp without altering its protein level. We provide evidences that Rack1 and Src regulate P-gp activity by modulating caveolin-1 (Cav1) phosphorylation. Importantly, Rack1 acts as a signaling hub and mediates Src binding to P-gp, thereby facilitating the phosphorylation of Cav1 by Src and abolishing the inhibitory effect of Cav1 on P-gp. Taken together, our results demonstrate the pivotal roles of Rack1 and Src in modulating P-gp activity in drug-resistant cells. Our findings also provide novel insights into the mechanism regulating P-gp transport activity. Rack1 may represent a new target for the development of effective therapies for reversing drug resistance.

ZIC1 acts a tumor suppressor in breast cancer by targeting survivin

In this study, we aimed to identify the tumor suppressive roles of zinc finger of the cerebellum 1 (ZIC1) in patients with malignant breast neoplasms and to examine the association between ZIC1 and survivin expression. For this purpose, 140 invasive breast cancer specimens, 1,075 RNA breast cancer samples from The Cancer Genome Atlas (TCGA), 6 human breast cancer cell lines and MCF-10A normal breast epithelial cells were selected in order to compare the expression level of ZIC1 with that of survivin via immunohistochemistry and western blot analysis. Subsequently, the MDA-MB-231 and SK-BR3 cells with a lower ZIC1 expression were transfected with rLV-Zic1-PGK-Puro lentivirus or rLV-ZsGreen-PGK-Puro lentivirus in order to observe any alterations in cell proliferation and apoptosis through MTT assay, colony formation assay, mitochondrial membrane potential assay and flow cytometric analysis, and to analyze the modulation of molecular mechanisms by western blot analysis. In addition, xenograft mouse models were constructed to explore the role of ZIC1 in the growth of implanted tumors. The results revealed that ZIC1 negatively correlated with survivin in tumors and cells, and a higher ZIC1 RNA expression indicated a better overall survival in the 1,075 TCGA RNA breast cancer samples. In vitro, the overexpression of ZIC1 inhibited cell proliferation, reduced mitochondrial membrane potential and promoted the apoptosis of the MDA-MB-231 and SK-BR3 breast cancer cells by inactivating the Akt/mTOR/P70S6K pathway, suppressing survivin expression, modulating the cell cycle, releasing cytochrome c (Cyto-c) into the cytosol and activating caspase proteins. In vivo, an elevated ZIC1 expression suppressed the growth of implanted tumors and downregulated survivin expression in tumors. On the whole, the findings of this study demonstrate that ZIC1 plays a tumor suppressive role in breast cancer, by targeting surviving, significantly downregulating its expression.

MiR-616-3p promotes angiogenesis and EMT in gastric cancer via the PTEN/AKT/mTOR pathway

Dysregulation of microRNAs has been demonstrated to be involved in a variety of biological events related to cancer, including proliferation, metastasis, angiogenesis and immune escape. MiR-616-3p is located on the chromosome region 12q13.3, however, its potential role and clinical implications in gastric cancer remain poorly understood. The current study aimed to investigate the potential role of miR-616-3p in gastric cancer. The results showed that miR-616-3p was up-regulated in cancer tissues. Higher expression of miR-616-3p in tumor tissues also predicted poor prognosis. Furthermore, loss- and gain-of-function in vitro revealed that miR-616-3p promoted angiogenesis and EMT in gastric cancer cells. Mechanistically, further analysis demonstrated that the effects of miR-616-3p on metastasis and angiogenesis occurred through the down-regulation of PTEN, a direct target of miR-616-3p. We propose that the restoration of PTEN expression may block miR-616-3p-induced EMT and angiogenesis. Collectively, our findings suggest that the miR-616-3p-PTEN signaling axis might be a potential therapeutic target for gastric cancer.

Natural compound Oblongifolin C confers gemcitabine resistance in pancreatic cancer by downregulating Src/MAPK/ERK pathways

Gemcitabine (GEM)-induced drug resistance is the major reason for the failure of chemotherapy in pancreatic cancer (PC). In this study, we found that Oblongifolin C (OC) efficiently inhibited PC cell proliferation by inducing G0/G1 arrest and apoptosis. Also, our mechanism study demonstrated that OC re-sensitized the GEM-resistant PC cells through the ubiquitin-proteasome-dependent degradation of Src, and then downregulating the MAPK pathway. Knockdown of Src plus OC resulted in a greater inhibitory effect in GEM-resistant PC cells. In contrast, Src overexpression reversed OC-mediated chemosensitization, thereby implicating Src in the action of OC. Moreover, our in vivo study showed that OC suppressed the tumor growth via the downregulation of Src, and enhanced the chemosensitivity of GEM-resistant PC to GEM. Overall, our results have revealed that OC is applicable as a promising agent for overcoming GEM-resistant PC, especially with aberrant Src expression.

BRAF and EGFR inhibitors synergize to increase cytotoxic effects and decrease stem cell capacities in BRAF(V600E)-mutant colorectal cancer cells

Mutations in the oncogene BRAF(V600E) are found in ~10% of colorectal cancers (CRCs) and are associated with poor prognosis. However, BRAF(V600E) has a limited response to the small-molecule drug, vemurafenib, a BRAF inhibitor, and BRAF inhibition is thought to cause a feedback activation of EGFR signaling that supports continued proliferation. In this study, we explored the effect of combined use of dabrafenib, a BRAF inhibitor, and cetuximab, an EGFR inhibitor, on BRAF(V600E)-mutant CRC stem cells and its possible mechanisms. Through cell viability analysis, flow cytometry, sphere forming, and western blot analysis, we found that the dabrafenib can synergize with cetuximab to reduce cell viability, induce enhanced apoptotic rates and cell cycle arrest in BRAF(V600E)-mutant HT-29 cells and inhibits stem cell capacities. Further, western blot analysis revealed that PTEN/Src/c-Myc pathway is possibly involved in the synergism between dabrafenib and cetuximab. Overall, our study shows that the combination of dabrafenib and cetuximab results in increased antitumor activity and decreased stem cell capacities in BRAF(V600E)-mutant CRC cells.

Connexin 32 affects doxorubicin resistance in hepatocellular carcinoma cells mediated by Src/FAK signaling pathway

Doxorubicin (DOX) is first-line chemotherapy for hepatocellular carcinoma (HCC), but the effect is not satisfactory. The resistance of HCC cells to DOX is the main reason leading to treatment failure. Therefore, it is necessary to study the mechanism of DOX resistance in HCC. In this study, expression of connexin (Cx)32 was significantly decreased in HCC tissues compared with corresponding paracancerous tissues, and activity of the Src/focal adhesion kinase (FAK) signaling pathway was significantly enhanced. Expression of Cx32 was closely associated with activity of the Src/FAK signaling pathway, Cx32, and the Src/FAK signaling pathway was also correlated with degree of HCC differentiation. In DOX-resistant HepG2 cells, compared with DOX-sensitive HepG2 cells, expression of Cx32 was significantly reduced and activity of the Src/FAK pathway increased. After silencing Cx32 in HepG2 cells, activity of the Src/FAK pathway increased and sensitivity to DOX decreased. In contrast, overexpression of Cx32 in HepG2/DOX cells decreased activity of the Src/FAK pathway and increased sensitivity to DOX. Dasatinib and KX2-391, inhibitors of the Src/FAK pathway, significantly increased the sensitivity of HepG2/DOX cells to DOX. The results suggest that Src/FAK is a downstream regulator of Cx32 and Cx32 regulates the sensitivity of HCC cells to DOX via the Src/FAK signaling pathway. Our study demonstrates a potential mechanism of DOX resistance in HCC cells and supports that Cx32-Src/FAK is an important target for reversing drug resistance of HCC.