Transgelin 2 Promotes Paclitaxel Resistance, Migration, and Invasion of Breast Cancer by Directly Interacting with PTEN and Activating PI3K/Akt/GSK-3β Pathway

Novel benzoylurea derivative decreases TRPM7 channel function and inhibits cancer cells migration

The transient receptor potential melastatin 7 channel (TRPM7) is a nonselective cation channel highly expressed in some human cancer tissues. TRPM7 is involved in the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of cancer cells. Modulation of TRPM7 could be a promising therapeutic strategy for treating cancer; however, efficient and selective pharmacological TRPM7 modulators are lacking. In this study we investigated N- [4- (4, 6-dimethyl- 2-pyrimidinyloxy) - 3- methylphenyl] -N' - [2 -(dimethylamino)] benzoylurea (SUD), a newly synthesized benzoylurea derivative, for its effects on cancer cell migration and EMT and on functional expression of TRPM7. Our previous studies showed that SUD induces cell cycle arrest and apoptosis of MCF-7 and BGC-823 cells (human breast cancer and gastric cancer cell lines, respectively). Here, we show that SUD significantly decreased the migration of both types of cancer cells. Moreover, SUD decreased vimentin expression and increased E-cadherin expression in both cell types, indicating that EMT is also decreased by SUD. Importantly, SUD potentially reduced the TRPM7-like current in a concentration-dependent manner and decreased TRPM7 expression through the PI3K/Akt signaling pathway. Finally, molecular docking simulations were used to investigate potential SUD binding sites on TRPM7. In summary, our research demonstrated that SUD is an effective TRPM7 inhibitor and a potential agent to suppress the metastasis of breast and gastric cancer by inhibiting TRPM7 expression and function.

Mechanoregulation and function of calponin and transgelin

It is well known that chemical energy can be converted to mechanical force in biological systems by motor proteins such as myosin ATPase. It is also broadly observed that constant/static mechanical signals potently induce cellular responses. However, the mechanisms that cells sense and convert the mechanical force into biochemical signals are not well understood. Calponin and transgelin are a family of homologous proteins that participate in the regulation of actin-activated myosin motor activity. An isoform of calponin, calponin 2, has been shown to regulate cytoskeleton-based cell motility functions under mechanical signaling. The expression of the calponin 2 gene and the turnover of calponin 2 protein are both under mechanoregulation. The regulation and function of calponin 2 has physiological and pathological significance, as shown in platelet adhesion, inflammatory arthritis, arterial atherosclerosis, calcific aortic valve disease, post-surgical fibrotic peritoneal adhesion, chronic proteinuria, ovarian insufficiency, and tumor metastasis. The levels of calponin 2 vary in different cell types, reflecting adaptations to specific tissue environments and functional states. The present review focuses on the mechanoregulation of calponin and transgelin family proteins to explore how cells sense steady tension and convert the force signal to biochemical activities. Our objective is to present a current knowledge basis for further investigations to establish the function and mechanisms of calponin and transgelin in cellular mechanoregulation.

Short Survey on the Protein Modifications in Plasma during SARS-CoV-2 Infection

Although the COVID-19 pandemic has ended, it is important to understand the pathology of severe SARS-CoV-2 infection associated with respiratory failure and high mortality. The plasma proteome, including protein modification by lipid peroxidation products in COVID-19 survivors (COVID-19; n = 10) and deceased individuals (CovDeath; n = 10) was compared in samples collected upon admission to the hospital, when there was no difference in their status, with that of healthy individuals (Ctr; n = 10). The obtained results show that COVID-19 development strongly alters the expression of proteins involved in the regulation of exocytosis and platelet degranulation (top 20 altered proteins indicated by analysis of variance; p-value (False Discovery Rate) cutoff at 5%). These changes were most pronounced in the CovDeath group. In addition, the levels of 4-hydroxynonenal (4-HNE) adducts increased 2- and 3-fold, whereas malondialdehyde (MDA) adducts increased 7- and 2.5-fold, respectively, in COVID-19 and CovDeath groups. Kinases and proinflammatory proteins were particularly affected by these modifications. Protein adducts with 15-deoxy-12,14-prostaglandin J2 (15d-PGJ2) were increased 2.5-fold in COVID-19 patients, including modifications of proteins such as p53 and STAT3, whereas CovDeath showed a decrease of approximately 60% compared with Ctr. This study for the first time demonstrates the formation of lipid metabolism products-protein adducts in plasma from survived and deceased COVID-19 patients, significantly distinguishing them, which may be a predictor of the course of SARS-CoV-2 infection.

Functional role of MicroRNA/PI3K/AKT axis in osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor that occurs in children and adolescents, and the PI3K/AKT pathway is overactivated in most OS patients. MicroRNAs (miRNAs) are highly conserved endogenous non-protein-coding RNAs that can regulate gene expression by repressing mRNA translation or degrading mRNA. MiRNAs are enriched in the PI3K/AKT pathway, and aberrant PI3K/AKT pathway activation is involved in the development of osteosarcoma. There is increasing evidence that miRNAs can regulate the biological functions of cells by regulating the PI3K/AKT pathway. MiRNA/PI3K/AKT axis can regulate the expression of osteosarcoma-related genes and then regulate cancer progression. MiRNA expression associated with PI3K/AKT pathway is also clearly associated with many clinical features. In addition, PI3K/AKT pathway-associated miRNAs are potential biomarkers for osteosarcoma diagnosis, treatment and prognostic assessment. This article reviews recent research advances on the role and clinical application of PI3K/AKT pathway and miRNA/PI3K/AKT axis in the development of osteosarcoma.

Addition of PI3K/AKT/mTOR inhibitors to fulvestrant for advanced HR+/HER2- breast cancer: a systematic review and meta-analysis

Purpose: To analyze whether adding PI3K/AKT/mTOR inhibitors to fulvestrant could restore endocrine therapy sensitivity for the treatment of postmenopausal patients with HR+, HER2- breast cancer. Methods: This meta-analysis was performed using RevMan 5.4 analysis software. Results: Nine studies that included a total of 3199 patients were analyzed. Compared with fulvestrant alone, the addition of PI3K/AKT/mTOR inhibitors significantly prolonged progression-free survival, overall survival and objective response rate of patients in both the total and PI3K-pathway-activated population. The number of grade 3-5 adverse events was also significantly higher. Conclusion: The addition of PI3K/AKT/mTOR to fulvestrant resulted in potential benefits; however, there may be a higher risk, which needs to be carefully managed.

Application of the Nicoya OpenSPR to Studies of Biomolecular Binding: A Review of the Literature from 2016 to 2022

The Nicoya OpenSPR is a benchtop surface plasmon resonance (SPR) instrument. As with other optical biosensor instruments, it is suitable for the label-free interaction analysis of a diverse set of biomolecules, including proteins, peptides, antibodies, nucleic acids, lipids, viruses, and hormones/cytokines. Supported assays include affinity/kinetics characterization, concentration analysis, yes/no assessment of binding, competition studies, and epitope mapping. OpenSPR exploits localized SPR detection in a benchtop platform and can be connected with an autosampler (XT) to perform automated analysis over an extended time period. In this review article, we provide a comprehensive survey of the 200 peer-reviewed papers published between 2016 and 2022 that use the OpenSPR platform. We highlight the range of biomolecular analytes and interactions that have been investigated using the platform, provide an overview on the most common applications for the instrument, and point out some representative research that highlights the flexibility and utility of the instrument.

TAGLN2 Promotes the Proliferation, Migration, Invasion, and EMT of Clear Cell Renal Cell Carcinoma Through the PI3K/Akt Signaling Pathway

The effect of Transgelin 2 (TAGLN2) on clear cell renal cell carcinoma (ccRCC) is unknown. This study explored the potential role and mechanism of ccRCC. The expression of TAGLN2 in Pan-cancers was analyzed using the Genotype-Tissue Expression (GTEx) and The Cancer Genome Atlas (TCGA) databases. TCGA-KIRC database was used to analyze subsequent prognostic survival, pathway enrichment, and immune infiltration. Relevant experimental methods could explain the effect of TAGLN2 expression on tumor cell proliferation, migration, invasion, and apoptosis. Apoptosis, proliferation, Epithelial-to-Mesenchymal Transition (EMT), and PI3K/AKT signaling pathway-related protein expression were determined through western blotting. In the TCGA + GTEx database, mRNA-TAGLN2 expression was clearly increased in pan-cancer tissues, and the same result was found in ccRCC patients based on KIRC analysis results. In addition, TAGLN2 was associated with poor clinical stage, pathological grade, and survival prognosis. TAGLN2 is highly expressed in ccRCC tissues and in vitro TAGLN2 silencing of cells inhibits the proliferation, migration, invasion, and EMT of ccRCC cancer cells. Furthermore, TAGLN2-related differential genes enriched in the PI3K/AKT signaling pathway were negatively regulated after TAGLN2 silencing. Moreover, TAGLN2 may promote tumor immune escape and increase the risk of distant metastasis in immune infiltration-related analyses. TAGLN2 can be used as a single indicator to explain the survival probability of patients with ccRCC. In vitro TAGLN2 silencing inhibited the malignant properties of ccRCC by blocking the PI3K/AKT signaling pathway. In addition, TAGLN2 contributes to tumor immune escape and may be a potential therapeutic target for ccRCC.

GASP1 enhances malignant phenotypes of breast cancer cells and decreases their response to paclitaxel by forming a vicious cycle with IGF1/IGF1R signaling pathway

There is a potential correlation between G-protein-coupled receptor-associated sorting protein 1 (GASP1) and breast tumorigenesis. However, its biological function and underlying molecular mechanism in breast cancer have not been clearly delineated. Here, we demonstrated that GASP1 was highly expressed in breast cancers, and patients harboring altered GASP1 showed a worse prognosis than those with wild-type GASP1. Functional studies showed that GASP1 knockout significantly suppressed malignant properties of breast cancer cells, such as inhibition of cell proliferation, colony formation, migration, invasion and xenograft tumor growth in nude mice as well as induction of G1-phase cell cycle arrest, and vice versa. Mechanistically, GASP1 inhibited proteasomal degradation of insulin-like growth factor 1 receptor (IGF1R) by competitively binding to IGF1R with ubiquitin E3 ligase MDM2, thereby activating its downstream signaling pathways such as NF-κB, PI3K/AKT, and MAPK/ERK pathways given their critical roles in breast tumorigenesis and progression. IGF1, in turn, stimulated GASP1 expression by activating the PI3K/AKT pathway, forming a vicious cycle propelling the malignant progression of breast cancer. Besides, we found that GASP1 knockout obviously improved the response of breast cancer cells to paclitaxel. Collectively, this study demonstrates that GASP1 enhances malignant behaviors of breast cancer cells and decreases their cellular response to paclitaxel by interacting with and stabilizing IGF1R, and suggests that it may serve as a valuable prognostic factor and potential therapeutic target in breast cancer.

A Review of Twenty Years of Research on the Regulation of Signaling Pathways by Natural Products in Breast Cancer

Breast cancer (BC) is the second leading cause of death among women, and it has become a global health issue due to the increasing number of cases. Different treatment options, including radiotherapy, surgery, chemotherapy and anti-estrogen therapy, aromatase inhibitors, anti-angiogenesis drugs, and anthracyclines, are available for BC treatment. However, due to its high occurrence and disease progression, effective therapeutic options for metastatic BC are still lacking. Considering this scenario, there is an urgent need for an effective therapeutic strategy to meet the current challenges of BC. Natural products have been screened as anticancer agents as they are cost-effective, possess low toxicity and fewer side effects, and are considered alternative therapeutic options for BC therapy. Natural products showed anticancer activities against BC through the inhibition of angiogenesis, cell migrations, proliferations, and tumor growth; cell cycle arrest by inducing apoptosis and cell death, the downstream regulation of signaling pathways (such as Notch, NF-κB, PI3K/Akt/mTOR, MAPK/ERK, and NFAT-MDM2), and the regulation of EMT processes. Natural products also acted synergistically to overcome the drug resistance issue, thus improving their efficacy as an emerging therapeutic option for BC therapy. This review focused on the emerging roles of novel natural products and derived bioactive compounds as therapeutic agents against BC. The present review also discussed the mechanism of action through signaling pathways and the synergistic approach of natural compounds to improve their efficacy. We discussed the recent in vivo and in vitro studies for exploring the overexpression of oncogenes in the case of BC and the current status of newly discovered natural products in clinical investigations.

MIF/SCL3A2 depletion inhibits the proliferation and metastasis of colorectal cancer cells via the AKT/GSK-3β pathway and cell iron death

This study investigated the mechanisms of migration inhibitory factor (MIF) and solute carrier family 3 member 2 (SLC3A2) in colorectal cancer progression. The levels of MIF and SLC3A2 expression in cells were measured by RT-qPCR. SW480 and SW620 cells were transfected with sh-MIF and sh-SLC3A2, respectively. MIF, SLC3A2, GPX4, E-cadherin and N-cadherin expression were detected by immunofluorescence (IF). CCK8 and Transwell assays were performed to detect cell proliferation and migration. Co-immunoprecipitation (CoIP) was used to measure the binding activity of MIF and SLC3A2. Finally, a nude mouse tumorigenicity assay was used to confirm the functions of MIF and SLC3A2 in colorectal cancer. Results showed that the levels of MIF and SLC3A2 expression were up-regulated in colorectal cancer cells. Inhibition of MIF or SLC3A2 expression prevented cell proliferation, migration, epithelial-mesenchymal transition (EMT) and invasion. In addition, knockdown of MIF and SLC3A2 promoted iron death in SW480 and SW620 cells. CoIP results showed that MIF and SLC3A2 directly interact with each other. Knockdown of both MIF and SLC3A2 inhibited tumour growth and metastasis via the AKT/GSK-3β pathway in vivo. The Akt/GSK-3β pathway was found to participate in regulating MIF and SLC3A2 both in vivo and in vitro. MIF and SLC3A2 might be potential biomarkers for monitoring the treatment of colorectal cancer.

Optimal Strategy and Benefit of Pulsed Therapy Depend On Tumor Heterogeneity and Aggressiveness at Time of Treatment Initiation

Therapeutic resistance is a fundamental obstacle in cancer treatment. Tumors that initially respond to treatment may have a preexisting resistant subclone or acquire resistance during treatment, making relapse theoretically inevitable. Here, we investigate treatment strategies that may delay relapse using mathematical modeling. We find that for a single-drug therapy, pulse treatment-short, elevated doses followed by a complete break from treatment-delays relapse compared with continuous treatment with the same total dose over a length of time. For tumors treated with more than one drug, continuous combination treatment is only sometimes better than sequential treatment, while pulsed combination treatment or simply alternating between the two therapies at defined intervals delays relapse the longest. These results are independent of the fitness cost or benefit of resistance, and are robust to noise. Machine-learning analysis of simulations shows that the initial tumor response and heterogeneity at the start of treatment suffice to determine the benefit of pulsed or alternating treatment strategies over continuous treatment. Analysis of eight tumor burden trajectories of breast cancer patients treated at Memorial Sloan Kettering Cancer Center shows the model can predict time to resistance using initial responses to treatment and estimated preexisting resistant populations. The model calculated that pulse treatment would delay relapse in all eight cases. Overall, our results support that pulsed treatments optimized by mathematical models could delay therapeutic resistance.

Tumor Suppressor Role of Wild-Type P53-Dependent Secretome and Its Proteomic Identification in PDAC

The study of the cancer secretome is gaining even more importance in cancers such as pancreatic ductal adenocarcinoma (PDAC), whose lack of recognizable symptoms and early detection assays make this type of cancer highly lethal. The wild-type p53 protein, frequently mutated in PDAC, prevents tumorigenesis by regulating a plethora of signaling pathways. The importance of the p53 tumor suppressive activity is not only primarily involved within cells to limit tumor cell proliferation but also in the extracellular space. Thus, loss of p53 has a profound impact on the secretome composition of cancer cells and marks the transition to invasiveness. Here, we demonstrate the tumor suppressive role of wild-type p53 on cancer cell secretome, showing the anti-proliferative, apoptotic and chemosensitivity effects of wild-type p53 driven conditioned medium. By using high-resolution SWATH-MS technology, we characterized the secretomes of p53-deficient and p53-expressing PDAC cells. We found a great number of secreted proteins that have known roles in cancer-related processes, 30 of which showed enhanced and 17 reduced secretion in response to p53 silencing. These results are important to advance our understanding on the link between wt-p53 and cancer microenvironment. In conclusion, this approach may detect a secreted signature specifically driven by wild-type p53 in PDAC.

HER4 Promotes Osteosarcoma Progression and Predicts Poor Prognosis through the PTEN-PI3K/AKT Pathway

Studies have reported a relationship between human epidermal growth factor receptor 4 (HER4), a ubiquitously expressed and unique member of the ErbB family, and clinicopathological features of osteosarcoma. However, further investigation is warranted. HER4 expression was analyzed by quantitative reverse transcription-polymerase chain reaction, western blotting, and immunohistochemistry. The relationship between HER4 expression and the prognosis of patients with osteosarcoma was determined by constructing a Kaplan-Meier curve. Cell viability and proliferation were investigated by MTT and colony formation assays. The mechanism underlying HER4-modulated proliferation and invasion/migration of osteosarcoma cells was determined by short hairpin RNA (shRNA) interference, colony formation, migration, invasion, and western blotting experiments. Spheroid formation assay and CD133+ cell populations were used to examine HER4-induced stem-like traits.

The present findings revealed that HER4 was overexpressed in both osteosarcoma cells and tissues. Moreover, this overexpression was associated with high Enneking stage, metastasis, and recurrence. Sh-HER4 showed obviously suppressed cell viability, colony formation, and invasion/migration. In addition, knockdown of HER4 markedly attenuated the spheroid size and proportion of CD133-positive cells, as well as the expression of stemness markers. Sh-HER4 also reduced the tumor size, downregulated the expression of phosphorylated-PI3K (p-PI3K) and p-AKT, and increased that of p-phosphatase and tensin homolog (p-PTEN) in mouse tissue. From a mechanistic perspective, HER4 knockdown activated p-PTEN and suppressed p-PI3K and p-AKT expression. HER4 promoted osteosarcoma progression through inactivation of the PTEN-PI3K/AKT pathway.

Taken together, the results indicate that HER4 represents a novel target in osteosarcoma progression and stemness modulation, and may be of value for the development of treatments against osteosarcoma.

AZD4547 targets the FGFR/Akt/SOX2 axis to overcome paclitaxel resistance in head and neck cancer

PURPOSE

Development of chemoresistance is one of the major obstacles to the treatment of head and neck squamous cell carcinoma (HNSCC). The PI3K/Akt pathway, involved in drug resistance, has been found to be overactivated in > 90% of HNSCCs. Aberrant activation of the FGF receptors (FGFRs) has been reported to cause overactivation of the PI3K/Akt pathway and to be associated with the maintenance of stem cell features, which is controlled via SOX2 expression. In this study, we aimed at investigating the potential of using AZD4547, an orally bioavailable FGFR inhibitor, to overcome taxol-resistance by targeting the FGFR/Akt/SOX2 axis in HNSCC.

METHODS

We initially evaluated FGFR2 and SOX2 expression using in silico tools. We analyzed the FGFR/Akt/SOX2 axis in normal/tumor tissue pairs and in recombinant FGF2 treated HNSCC cells. Next, we explored the effects of AZD4547 alone and in combination with taxol on the proliferation, migration and colony forming capacities of parental/taxol-resistant cells using in vitro models.

RESULTS

We found that the p-FGFR, p-AKT, p-GSK-3β and SOX2 expression levels were higher in tumor tissues than in its corresponding normal tissues, and that AZD4547 effectively suppressed the expression of FGFR and its downstream targets in recombinant FGF2 treated HNSCC cells. We also found that AZD4547 diminished the viability, migration and colony forming capacity of HNSCC cells, and that co-treatment with taxol potentiated the impact of taxol on these cells. Finally, we found that AZD4547 inhibited the overexpressed FGFR/Akt/SOX2 axis and profoundly suppressed cancer-related phenotypes in taxol-resistant HNSCC cells.

CONCLUSION

From our data we conclude that AZD4547 may increase the impact of taxol during HNSCC treatment. We suggest AZD4547 as a therapeutic agent to overcome taxol-resistance.

Discovery of TGFBR1 (ALK5) as a potential drug target of quercetin glycoside derivatives (QGDs) by reverse molecular docking and molecular dynamics simulation

Quercetin glycoside derivatives (QGDs) are a class of common compounds with a wide range of biological activities, such as antitumor activities. However, their molecular targets associated with biological activities have not been investigated. In this study, four common QGDs with mutual bioconversion were selected, and studied in the large-scale reverse docking experiments. Network pharmacology analysis showed that most of the four QGDs can bind several potential protein targets that were closely related to breast cancer disease. Among them, a druggable protein, transforming growth factor beta receptor I (TGFBR1/ALK5) was screened via high docking scores for the four QGDs. This protein has been proven to be an important target for the treatment of breast cancer by regulating the proliferation and migration of cancer cells in the past. Subsequently, the molecular dynamics (MD) simulation and MM/GBSA calculation demonstrated that all QGDs could thermodynamically bind with TGFBR1, indicating that TGFBR1 might be one of the potential protein targets of QGDs. Finally, the cytotoxicity test and wound-healing migration assay displayed that isoquercetin, which can perform best in MD experiment, might be a promising agent in the treatment of breast cancer metastasis.

LINC00511 promotes gastric cancer progression by regulating SOX4 and epigenetically repressing PTEN to activate PI3K/AKT pathway

Gastric cancer (GC) serves as a common malignancy. Long non-coding RNAs (lncRNAs) have been proven to regulate many cancers, including GC. Long intergenic non-protein-coding RNA 511 (LINC00511) has been poorly studied in GC, but its detailed regulatory mechanism has not been identified. Here, LINC00511 was detected to be highly expressed in GC cells. Functional assays were conducted and uncovered that LINC00511 boosted cell proliferation, migration, stemness and EMT process while inhibiting the apoptosis of GC cells. From a series of mechanism experiments, it was found that at the transcriptional level, LINC00511 recruited EZH2 (enhancer of zeste 2 polycomb repressive complex 2 subunit) to the promoter of PTEN (phosphatase and tensin homolog) and facilitated methylation of PTEN promoter. LINC00511 epigenetically repressed PTEN to activate the PI3K/AKT pathway. Moreover, SRY-box transcription factor 4 (SOX4) activated the transcription of LINC00511. At the post-transcriptional level, LINC00511 sponged miR-195-5p to elevate SOX4 expression in GC cells. On the whole, the present study disclosed that SOX4-induced LINC00511 activated SOX4 via competing endogenous RNA (ceRNA) pattern and epigenetically repressed PTEN to activate PI3K/AKT pathway by recruiting EZH2, thus facilitating GC cell proliferation, migration and stemness while inhibiting GC cell apoptosis.

Determining the domain-level reaction-diffusion properties of an actin-binding protein transgelin-2 within cells

Proteins in cells undergo repeated binding to other molecules, thereby reducing the apparent extent of their intracellular diffusion. While much effort has been made to analytically decouple these combined effects of pure diffusion and chemical binding, it is difficult with conventional approaches to attribute the measured quantities to the nature of specific domains of the proteins. Motivated by the common goal in cell signaling research aimed at identifying the domains responsible for particular intermolecular interactions, here we describe a framework for determining the local physicochemical properties of cellular proteins associated with immobile scaffolds. To validate this new approach, we apply it to transgelin-2, an actin-binding protein whose intracellular dynamics remains elusive. We develop a fluorescence recovery after photobleaching (FRAP)-based framework, in which comprehensive combinations of domain-deletion mutants are created, and the difference among them in FRAP response is analyzed. We demonstrate that transgelin-2 in actin stress fibers (SFs) interacts with F-actin via two separate domains, and the chemical properties are determined for the individual domains. Its pure diffusion properties independent of the association to F-actin is also obtained. Our approach will thus be useful, as presented here for transgelin-2, in addressing the signaling mechanism of cellular proteins associated with SFs.

PI3 kinase signaling pathway in hematopoietic cancers: A glance in miRNA's role

Hematopoietic cancers are among the most common malignancies worldwide, which are divided into different types depending on the origin of tumor cells. In recent years, the pivotal role of different signaling pathways in the onset and progression of these cancer types has been well established. One of these pathways, whose role in blood malignancies has been well-defined, is PI3K/mTOR/AKT axis. The signaling pathway involves in a wide variety of important biological events in cells. It is clear that dysregulation of mediators involved in PI3 kinase signaling takes a pivotal role in cancer development. Considering the undeniable role of miRNAs, as one of the well-known families of non-coding RNAs, in gene regulation, we aimed to review the role of miRNAs in regulation of PI3 kinase signaling effectors in hematopoietic cancers.

Activation of PI3K/AKT/mTOR Pathway Causes Drug Resistance in Breast Cancer

Although chemotherapy, targeted therapy and endocrine therapy decrease rate of disease recurrence in most breast cancer patients, many patients exhibit acquired resistance. Hyperactivation of the PI3K/AKT/mTOR pathway is associated with drug resistance and cancer progression. Currently, a number of drugs targeting PI3K/AKT/mTOR are being investigated in clinical trials by combining them with standard therapies to overcome acquired resistance in breast cancer. In this review, we summarize the critical role of the PI3K/AKT/mTOR pathway in drug resistance, the development of PI3K/AKT/mTOR inhibitors, and strategies to overcome acquired resistance to standard therapies in breast cancer.

Transgelins: Cytoskeletal Associated Proteins Implicated in the Metastasis of Colorectal Cancer

Transgelins, including transgelin-1 (T-1), transgelin-2 (T-2), and transgelin-3 (T-3), are a family of actin-binding proteins (ABPs) that can alter the structure and morphology of the cytoskeleton. These proteins function by regulating migration, proliferation and apoptosis in many different cancers. Several studies have shown that in various types of tumor cells, including colorectal cancer (CRC) cells, and in the tumor microenvironment, the expression and biological effects of transgelins are diverse and may transform during tumor progression. Previous researches have demonstrated that transgelin levels are positively correlated with metastasis in CRC, and down-regulating their expression can inhibit this process. In advanced disease, T-1 is a tumor activator with increasing expression, and T-2 expression increases with the progression of CRC. Finally, T-3 is only expressed in neurons and is not associated with CRC. This evidence suggests that T-1 and T-2 are potential biomarkers and therapeutic targets for CRC metastasis.

PI3K/AKT pathway as a key link modulates the multidrug resistance of cancers

Multidrug resistance (MDR) is the dominant challenge in the failure of chemotherapy in cancers. Phosphatidylinositol 3-kinase (PI3K) is a lipid kinase that spreads intracellular signal cascades and regulates a variety of cellular processes. PI3Ks are considered significant causes of chemoresistance in cancer therapy. Protein kinase B (AKT) is also a significant downstream effecter of PI3K signaling, and it modulates several pathways, including inhibition of apoptosis, stimulation of cell growth, and modulation of cellular metabolism. This review highlights the aberrant activation of PI3K/AKT as a key link that modulates MDR. We summarize the regulation of numerous major targets correlated with the PI3K/AKT pathway, which is further related to MDR, including the expression of apoptosis-related protein, ABC transport and glycogen synthase kinase-3 beta (GSK-3β), synergism with nuclear factor kappa beta (NF-κB) and mammalian target of rapamycin (mTOR), and the regulation of glycolysis.

Role of PI3K/AKT pathway in cancer: the framework of malignant behavior

Given that the PI3K/AKT pathway has manifested its compelling influence on multiple cellular process, we further review the roles of hyperactivation of PI3K/AKT pathway in various human cancers. We state the abnormalities of PI3K/AKT pathway in different cancers, which are closely related with tumorigenesis, proliferation, growth, apoptosis, invasion, metastasis, epithelial-mesenchymal transition, stem-like phenotype, immune microenvironment and drug resistance of cancer cells. In addition, we investigated the current clinical trials of inhibitors against PI3K/AKT pathway in cancers and found that the clinical efficacy of these inhibitors as monotherapy has so far been limited despite of the promising preclinical activity, which means combinations of targeted therapy may achieve better efficacies in cancers. In short, we hope to feature PI3K/AKT pathway in cancers to the clinic and bring the new promising to patients for targeted therapies.

Long noncoding RNA lncARSR confers resistance to Adriamycin and promotes osteosarcoma progression

One of the significant challenges for chemotherapy is the appearance of resistance to compounds. Although several signaling pathways have been implicated in the development of Adriamycin (ADM) resistance, mechanisms involved in ADM-resistant osteosarcoma progression remain unknown. The present study attempted to illustrate the role of long noncoding RNA ARSR (lncARSR) in the development of adapted ADM resistance. We found lncARSR overexpressed in the Adriamycin-resistant cell lines U2OS/ADM and MG63/ADM, accompanied with acquired multidrug resistance against to paclitaxel and cisplatin. Overexpression of lncARSR triggered rhodamine 123 efflux and survival, as well as the migration of Adriamycin-resistant cells. Inversely, the depletion of lncARSR promoted rhodamine 123 retention and apoptosis, while reducing the motility of ADM-resistant cells. Further investigation revealed that the upregulation of lncARSR enhanced multidrug resistance-associated protein-1 (MRP1), apoptosis inhibitor Survivin, and matrix metalloproteinase-2 (MMP2) through activating AKT. The reduction of lncARSR overcame the resistance to ADM in U2OS/ADM mouse model. The current study gained novel evidence for understanding the mechanisms underlying adaptive ADM resistance and provided rationales to improve clinical outcomes of refractory osteosarcoma.

Akt-targeted therapy as a promising strategy to overcome drug resistance in breast cancer - A comprehensive review from chemotherapy to immunotherapy

Breast cancer is the most frequently occurring cancer in women. Chemotherapy in combination with immunotherapy has been used to treat breast cancer. Atezolizumab targeting the protein programmed cell death-ligand (PD-L1) in combination with paclitaxel was recently approved by the Food and Drug Administration (FDA) for Triple-Negative Breast Cancer (TNBC), the most incurable type of breast cancer. However, the use of such drugs is restricted by genotype and is effective only for those TNBC patients expressing PD-L1. In addition, resistance to chemotherapy with drugs such as lapatinib, geftinib, and tamoxifen can develop. In this review, we address chemoresistance in breast cancer and discuss Akt as the master regulator of drug resistance and several oncogenic mechanisms in breast cancer. Akt not only directly interacts with the mitogen-activated protein (MAP) kinase signaling pathway to affect PD-L1 expression, but also has crosstalk with Notch and Wnt/β-catenin signaling pathways involved in cell migration and breast cancer stem cell integrity. In this review, we discuss the effects of tyrosine kinase inhibitors on Akt activation as well as the mechanism of Akt signaling in drug resistance. Akt also has a crucial role in mitochondrial metabolism and migrates into mitochondria to remodel breast cancer cell metabolism while also functioning in responses to hypoxic conditions. The Akt inhibitors ipatasertib, capivasertib, uprosertib, and MK-2206 not only suppress cancer cell proliferation and metastasis, but may also inhibit cytokine regulation and PD-L1 expression. Ipatasertib and uprosertib are undergoing clinical investigation to treat TNBC. Inhibition of Akt and its regulators can be used to control breast cancer progression and also immunosuppression, while discovery of additional compounds that target Akt and its modulators could provide solutions to resistance to chemotherapy and immunotherapy.