Perifosine enhances mTORC1-targeted cancer therapy by activation of GSK3β in NSCLC cells

Decoding the role of glucocorticoid-regulated kinase 1 in Alzheimer's disease: a promising path toward novel therapeutic strategies

Serum glucocorticoid-regulated kinase 1 (SGK1) is a ubiquitous serine and threonine kinase and has been implicated in many physiological processes including cell survival, proliferation, metabolism, and ion transport. The dysregulation of SGK1 has also been linked to various diseases including cardiometabolic diseases, cancer, and neurological disorders. Recent evidence indicates that SGK1 is influential in the key Alzheimer's disease (AD) pathologic mechanisms including memory and cognitive dysfunction and AD hallmarks such as amyloid beta (Aβ) plaques and neurofibrillary tangles. Overexpression of SGK1 affects the Aβ metabolism and affects the pathway and enzymes disserting Aβ. SGK1 also increases dendritic spine density through regulation of actin polymerization, which increases the ratio of synaptic contacts leading to possible enhancement of memory and cognitive function. The modulation of SGK1 dysfunction in AD pathology leads to tau hyperphosphorylation through glycogen synthase kinase-3 (GSK-3β), thereby promoting the formation of neurofibrillary tangles (NFTs). In addition, SGK1 enhances neuroinflammation through the activation of microglia as well as astrocytes into the release of pro-inflammatory cytokines and neuronal damage. Consequently, SGK1 has been implicated in pathological processes in neurodegeneration and further research is required to delineate its dual role. In this review, we focus on the role of SGK1 in neurodegenerative diseases, specifically in AD. In addition, it discusses the role of SGK1 signaling pathways and the possible SGK1 as a therapeutic target in memory formation and Aβ metabolism.

Novel therapeutic approaches for non-small cell lung cancer: an updated view

Non-small cell lung cancer (NSCLC) continues to be one of the leading causes of cancer-related mortality globally. Most patients who undergo surgical procedures may encounter distant metastasis or local recurrence, necessitating supplementary treatments such as radiation therapy, chemotherapy, or targeted therapy as adjuvant alternatives. Recent advancements in molecular biology and immunotherapy have paved the way for innovative therapeutic approaches that target specific genetic mutations and promote the immune response against tumour cells. This review explores emerging therapies, including targeted therapies such as tyrosine kinase inhibitors (TKIs) for actionable mutations (e.g., EGFR, ALK, ROS1), as well as the role of immune checkpoint inhibitors (ICIs) that employ the body's immune system to combat cancer. Additionally, we discuss the potential of exosome therapies, as well as promising nanotherapeutic options for the treatment of NSCLC. This study attempts to provide a thorough overview of the changing landscape of NSCLC treatment and its implications for enhancing patient outcomes by presenting these innovative techniques.

Recent advances in non-small cell lung cancer targeted therapy; an update review

Lung cancer continues to be the leading cause of cancer-related death worldwide. In the last decade, significant advancements in the diagnosis and treatment of lung cancer, particularly NSCLC, have been achieved with the help of molecular translational research. Among the hopeful breakthroughs in therapeutic approaches, advances in targeted therapy have brought the most successful outcomes in NSCLC treatment. In targeted therapy, antagonists target the specific genes, proteins, or the microenvironment of tumors supporting cancer growth and survival. Indeed, cancer can be managed by blocking the target genes related to tumor cell progression without causing noticeable damage to normal cells. Currently, efforts have been focused on improving the targeted therapy aspects regarding the encouraging outcomes in cancer treatment and the quality of life of patients. Treatment with targeted therapy for NSCLC is changing rapidly due to the pace of scientific research. Accordingly, this updated study aimed to discuss the tumor target antigens comprehensively and targeted therapy-related agents in NSCLC. The current study also summarized the available clinical trial studies for NSCLC patients.

Targeting BET proteins inhibited the growth of non-small cell lung carcinoma through downregulation of Met expression

Hepatocyte growth factor receptor (HGFR or Met) upregulation has been proven to play important roles in non-small cell lung carcinoma (NSCLC). Interestingly, chemoresistance against epidermal growth factor receptor (EGFR) inhibitors including erlotinib and gefitinib was also related to Met. Targeting bromodomain and extra terminal domain (BET) proteins, especially BRD4, has shown inhibitory effects on lung cancer, but the mechanism is unclear. Herein, we found that JQ1 (BET inhibitor) suppressed NSCLC cell growth, reduced the Met expression, and contributed to inactivation of PI3K/Akt and MAPK/ERK pathways. Moreover, another BET protein inhibitor I-BET151, or BRD4 depletion, also inhibited NSCLC cell growth and downregulated Met. JQ1 inhibited HGF-induced cell growth and Met/PI3K/Akt activation, also inhibited A549 tumor growth in xenograft mouse models, in parallel with Met downregulation. Moreover, JQ1 inhibited the growth of paired erlotinib-sensitive and resistant HCC827 cells in parallel with Met downregulation and PI3K/Akt signaling inactivation. JQ1 also exerted inhibitory influences on the growth of erlotinib-sensitive and resistant HCC827 tumors in xenograft mouse models. These results suggested that targeting BET proteins inhibited NSCLC via downregulating Met and inactivating PI3K/AKT pathway. Our findings reveal a novel mechanism of BET proteins implicated in NSCLC progression with Met taken into consideration.

Trichostatin A downregulates bromodomain and extra-terminal proteins to suppress osimertinib resistant non-small cell lung carcinoma

BACKGROUND

The third-generation epithelial growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have shown significant therapeutic effects on patients with non-small cell lung carcinoma (NSCLC) who carry active EGFR mutations, as well as those who have developed acquired resistance to the first-generation of EGFR-TKIs due to the T790M mutation. However, most patients develop drug resistance after 8-10 months of treatment. Currently, the mechanism has not been well clarified, and new therapeutic strategies are urgently needed.

METHODS

Osimertinib resistant cell lines were established by culturing sensitive cells in chronically increasing doses of osimertinib. The anticancer effect of reagents was examined both in vitro and in vivo using the sulforhodamine B assay and a xenograft mouse model. The molecular signals were detected by western blotting. The combination effect was analyzed using CompuSyn software.

RESULTS

We found that bromodomain and extra-terminal proteins (BETs) were upregulated in osimertinib resistant (H1975-OR) cells compared with those in the paired parental cells (H1975-P), and that knockdown of BETs significantly inhibited the growth of H1975-OR cells. The BET inhibitor JQ1 also exhibited stronger growth-inhibitory effects on H1975-OR cells and a greater expression of BETs and the downstream effector c-Myc than were observed in H1975-P cells. The histone deacetylase (HDAC) inhibitor trichostatin A (TSA) showed stronger growth suppression in H1975-OR cells than in H1975-P cells, but vorinostat, another HDAC inhibitor, showed equal inhibitory efficacy in both cell types. Consistently, downregulation of BET and c-Myc expression was greater with TSA than with vorinostat. TSA restrained the growth of H1975-OR and H1975-P xenograft tumors. The combination of TSA and JQ1 showed synergistic growth-inhibitory effects in parallel with decreased BET and c-Myc expression in both H1975-OR and H1975-P cells and in xenograft nude mouse models. BETs were not upregulated in osimertinib resistant HCC827 cells compared with parental cells, while TSA and vorinostat exhibited equal inhibitory effects on both cell types.

CONCLUSION

Upregulation of BETs contributed to the osimertinib resistance of H1975 cells. TSA downregulated BET expression and enhanced the growth inhibitory effect of JQ1 both in vitro and in vivo. Our findings provided new strategies for the treatment of osimertinib resistance.

p70S6K Promotes Acquired Resistance of Erlotinib Through Induction of Epithelial-Mesenchymal Transition in Non-Small Cell Lung Carcinoma

Background

Lung cancer is the leading cause of cancer-related deaths. EGFR tyrosine kinase inhibitors, such as erlotinib, were approved for non-small cell lung carcinoma patients with EGFR mutations. However, the acquired resistance of these inhibitors has not been fully clarified. Therefore, clarifying the mechanism and developing new rationales to overcome the drug resistance are urgently needed.

Methods

A pair of erlotinib sensitive and resistant cells was used to identify the key molecules in mediating erlotinib resistance. Loss- or gain-of-function study was used to confirm the effects of the key molecules. Xenograft mouse model and human cancer tissue sample studies were conducted for further corroboration.

Results

HCC827 cells with acquired resistance to erlotinib underwent epithelial-mesenchymal transition and exhibited enhanced p70S6K signaling compared to parental sensitive cells. Moreover, in erlotinib resistant cells, downregulation of p70S6K expression using either siRNA or shRNA reversed EMT and partially overcame erlotinib resistance. Meanwhile, in erlotinib sensitive cells, overexpression of p70S6K promoted EMT and induced erlotinib resistance. Upregulation of p70S6K signaling in erlotinib resistant cells was caused by reduced GSK3β-mediated protein degradation of mTOR and raptor. Additionally, p70S6K silencing suppressed the growth of erlotinib resistant cells in a xenograft mouse model. Finally, we found a correlation between p70S6K and E-cadherin expression in human non-small-cell lung cancer (NSCLC) tissue samples.

Conclusion

Our findings suggest that p70S6K-induced EMT plays an important role in the acquired resistance of erlotinib and provides a novel therapeutic rationale of targeting p70S6K in NSCLC therapy.

Targeting BRD4 proteins suppresses the growth of NSCLC through downregulation of eIF4E expression

Lung cancer is the leading cause of cancer-related death worldwide. Bromodomain and extraterminal domain (BET) proteins act as epigenome readers for gene transcriptional regulation. Among BET family members, BRD4 was well studied, but for its mechanism in non-small cell lung carcinoma has not been elucidated. eIF4E regulates gene translation and has been proved to play an important role in the progression of lung cancer. In this study, we first confirmed that BET inhibitors JQ1 and I-BET151 suppressed the growth of NSCLCs, in parallel with downregulated eIF4E expression. Then we found that knockdown of BRD4 expression using siRNAs inhibited the growth of NSCLCs as well as decreased eIF4E protein levels. Moreover, overexpression of eIF4E partially abrogated the growth inhibitory effect of JQ1, while knockdown of eIF4E enhanced the inhibitory effect of JQ1. Furthermore, JQ1 treatment or knockdown of BRD4 expression decreased eIF4E mRNA levels and inhibited its promoter activity by luciferase reporter assay. JQ1 treatment significantly decreased the binding of eIF4E promoter with BRD4. Finally, JQ1 inhibited the growth of H460 tumors in parallel with downregulated eIF4E mRNA and protein levels in a xenograft mouse model. These findings suggest that inhibition of BET by JQ1, I-BET151, or BRD4 silencing suppresses the growth of non-small cell lung carcinoma through decreasing eIF4E transcription and subsequent mRNA and protein expression. Considering that BET regulates gene transcription epigenetically, our findings not only reveal a new mechanism of BET-regulated eIF4E in lung cancer, but also indicate a novel strategy by co-targeting eIF4E for enhancing BET-targeted cancer therapy.

p70S6K promotes IL-6-induced epithelial-mesenchymal transition and metastasis of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the fifth most common cancer worldwide and a common cause of cancer-related death, with a 5-year survival rate of less than 60%. IL-6 has been suggested to play an important role in cancer metastasis, but its mechanism in HNSCC has not been fully clarified. p70S6K has been reported to induce epithelial-mesenchymal transition (EMT) of ovarian cancer, but its role in HNSCC remains unknown. In this study, we found that p70S6K and IL-6 were upregulated in high-metastatic HNSCC cell lines that underwent EMT when compared to paired low-metastatic cell lines. Overexpression of p70S6K promoted EMT and migration of HNSCC cells, while downregulation of p70S6K attenuated IL-6-induced EMT and cell migration. Furthermore, IL-6-induced p70S6K activation was attenuated by inhibitors of the PI3K/Akt/mTOR, MAPK/ERK, and JAK/STAT3 signaling pathways, suggesting that it located downstream of these pathways. These findings suggest that p70S6K promotes IL-6-induced EMT and metastasis of HNSCC. Targeting p70S6K for HNSCC therapy may benefit patients through the inhibition of tumor growth, as well as metastasis.

Upregulation of miR-3607 promotes lung adenocarcinoma proliferation by suppressing APC expression

Lung cancer is the leading cause of worldwide cancer-related deaths, although many drugs and new therapeutic approaches have been used, the 5-years survival rate is still low for lung cancer patients. microRNAs have been shown to regulate lung cancer initiation and development, here we studied the role of miR-3607 in lung cancer cell proliferation. We found miR-3607 was upregulated in lung cancer tissues and cells, miR-3607 overexpression promoted lung cancer cell A549 proliferation determined by MTT assay, colony formation assay, anchorage-independent growth ability assay and bromodeoxyuridine incorporation assay, while the opposite phenotypes were shown when miR-3607 was knocked down. Predicted analysis suggested a Wnt signaling pathway regulator adenomatous polyposis coli (APC) was the target of miR-3607, miR-3607 could directly bind to the 3'UTR of APC, and promoted Cyclin D1 and c-Myc expression which can be suppressed by APC. Double knockdown of miR-3607 and APC copied the phenotypes of miR-3607 overexpression, suggesting miR-3607 promoted lung cancer cell A549 proliferation by targeting APC. In conclusion, our study suggested miR-3607 contributes to lung cancer cell proliferation by inhibiting APC.

Akt targeting as a strategy to boost chemotherapy efficacy in non-small cell lung cancer through metabolism suppression

Metabolic reprogramming is a hallmark of cancer development, mediated by genetic and epigenetic alterations that may be pharmacologically targeted. Among oncogenes, the kinase Akt is commonly overexpressed in tumors and favors glycolysis, providing a rationale for using Akt inhibitors. Here, we addressed the question of whether and how inhibiting Akt activity could improve therapy of non-small cell lung cancer (NSCLC) that represents more than 80% of all lung cancer cases. First, we demonstrated that Akt inhibitors interacted synergistically with Microtubule-Targeting Agents (MTAs) and specifically in cancer cell lines, including those resistant to chemotherapy agents and anti-EGFR targeted therapies. In vivo, we further revealed that the chronic administration of low-doses of paclitaxel - i.e. metronomic scheduling - and the anti-Akt perifosine was the most efficient and the best tolerated treatment against NSCLC. Regarding drug mechanism of action, perifosine potentiated the pro-apoptotic effects of paclitaxel, independently of cell cycle arrest, and combining paclitaxel/perifosine resulted in a sustained suppression of glycolytic and mitochondrial metabolism. This study points out that targeting cancer cell bioenergetics may represent a novel therapeutic avenue in NSCLC, and provides a strong foundation for future clinical trials of metronomic MTAs combined with Akt inhibitors.

Oncogenic miR-9 is a target of erlotinib in NSCLCs

EGFR-targeted cancer therapy is a breakthrough in non-small cell carcinoma. miRNAs have been proved to play important roles in cancer. Currently, for the role of miRNAs in EGFR-targeted cancer therapy is unclear. In this study, first we found that erlotinib reduced the expression of miR-9. MiR-9 expression was increased in human lung cancer tissues compared with peripheral normal tissues, and miR-9 promoted the growth of NSCLC cells. Overexpression of miR-9 decreased the growth inhibitory effect of erlotinib. Second, miR-9 decreased FoxO1 expression by directly inhibition of its mRNA translation. Adenovirus-mediated overexpression of FoxO1 or siRNA-mediated downregulation of FoxO1 negatively regulated cell growth. And exogenous overexpression FoxO1 reduced the pro-growth effect of miR-9. Finally, we found that erlotinib upregulated FoxO1 protein expression. Moreover, overexpression of miR-9 decreased erlotinib-induced FoxO1 expression, and overexpression of FoxO1 enhanced the growth inhibitory effects of erlotinib. Additionally, we found that erlotinib downregulates miR-9 expression through suppressing the transcrption of miR-9-1 and enhanced DNA methylation maybe involved. These findings suggest that oncogenic miR-9 targeted FoxO1 to promote cell growth, and downregulation of this axis was involved in erlotinib’s growth inhibitory effects. Clarifying the regulation of miRNAs by erlotinib may indicate novel strategies for enhancing EGFR-targeted cancer therapy.

Antitumor Lipids--Structure, Functions, and Medical Applications

Cell proliferation and metastasis are considered hallmarks of tumor progression. Therefore, efforts have been made to develop novel anticancer drugs that inhibit both the proliferation and the motility of tumor cells. Synthetic antitumor lipids (ATLs), which are chemically divided into two main classes, comprise (i) alkylphospholipids (APLs) and (ii) alkylphosphocholines (APCs). They represent a new entity of drugs with distinct antiproliferative properties in tumor cells. These compounds do not interfere with the DNA or mitotic spindle apparatus of the cell, instead, they incorporate into cell membranes, where they accumulate and interfere with lipid metabolism and lipid-dependent signaling pathways. Recently, it has been shown that the most commonly studied APLs inhibit proliferation by inducing apoptosis in malignant cells while leaving normal cells unaffected and are potent sensitizers of conventional chemo- and radiotherapy, as well as of electrical field therapy. APLs resist catabolic degradation to a large extent, therefore accumulate in the cell and interfere with lipid-dependent survival signaling pathways, notably PI3K-Akt and Raf-Erk1/2, and de novo phospholipid biosynthesis. They are internalized in the cell membrane via raft domains and cause downstream reactions as inhibition of cell growth and migration, cell cycle arrest, actin stress fibers collapse, and apoptosis. This review summarizes the in vitro, in vivo, and clinical trials of most common ATLs and their mode of action at molecular and biochemical levels.

New development of inhibitors targeting the PI3K/AKT/mTOR pathway in personalized treatment of non-small-cell lung cancer

Lung cancer is the leading cause of cancer-related death worldwide. Non-small-cell lung cancer (NSCLC) is the most common pathological type of lung cancer, divided into squamous cell carcinoma and adenocarcinoma. Despite better techniques of surgery and improvement in adjuvant and neoadjuvant therapy, the median survival of advanced NSCLC is only 8-10 months. With increased understanding of molecular alternations in NSCLC, considerable efforts have focused on the development of personalized molecular-targeted therapies. The PI3K/AKT/mTOR pathway regulates tumor development, growth, and proliferation of NSCLC. Various novel inhibitors targeting this pathway have been identified in preclinical studies or clinical trials. Some genetic alternations may be considered sensitive or resistant biomarkers to these inhibitors. Sometimes, upregulation of RTK and the downstream PI3K pathway or upregulation of the ERK pathway by compensatory feedback reactivation in response to these inhibitors also lead to drug resistance. Therefore, combination therapy of these inhibitors and other targeted inhibitors such as EGFR-TKI or MEK inhibitors according to genetic status and categories of inhibitors is required to enhance the efficacy of these inhibitors. Here, we reviewed the genetic status of the PI3K/AKT/mTOR pathway in NSCLC and the novel inhibitors targeting this pathway in preclinical or clinical studies, exploring the possible genetic alternations related to different inhibitors and the means to enhance the antitumor effect in NSCLC.

Upregulation of the eIF4E signaling pathway contributes to the progression of gastric cancer, and targeting eIF4E by perifosine inhibits cell growth

The increase of eukaryotic translation initiation factor 4E (eIF4E) expression is frequently observed in several types of cancer, making eIF4E an attractive anticancer drug target. However, the role of eIF4E in gastric cancer pathogenesis remains unclear. Perifosine is a bioavailable alkylphospholipid exhibiting antitumor activity in a series of cancer types. In this study, gastric cancer cell lines were selected to explore the role of eIF4E as a potential target for treating human gastric cancer. The expression of total eIF4E (T-eIF4E)and phosphorylated eIF4E (p-eIF4E) in gastric cancer samples was detected by immunohistochemical assay. RNA interference was used to silence eIF4E expression. Sulforhodamine B assay was performed to evaluate tumor cell viability. Colony formation assay was used to examine the effects of eIF4E small interfering RNA (siRNA) or perifosine on colony formation. The mRNA levels of eIF4E were analyzed by qRT-PCR and western blot analysis was carried out to evaluate the expression of Akt and eIF4E. The results showed that increased expression levels of T-eIF4E and p-eIF4E were found in gastric cancer tissues and cells. Reduced eIF4E expression blocked the proliferation of gastric cancer cells. Perifosine downregulated the T-eIF4E and p-eIF4E levels in a dose- and time-dependent manner; it also inhibited the growth of gastric cancer cells. Moreover, this inhibitory effect was significantly enhanced by the combination of eIF4E siRNA and perifosine treatments. Our results indicate that eIF4E gene silencing can inhibit tumor cell growth, and eIF4E can be developed as a promising therapeutic target for gastric cancer.

SNS-032 inhibits mTORC1/mTORC2 activity in acute myeloid leukemia cells and has synergistic activity with perifosine against Akt

BACKGROUND

Acute myeloid leukemia (AML) is a heterogeneous disorder with aberrant regulation of a variety of signal pathways. Therefore, simultaneous targeting of two or even more deregulated signal transduction pathways is needed to overcome drug resistance. Previously, it was reported that SNS-032, a selective cyclin-dependent kinase inhibitor, is an effective agent for treatment of AML; however, the molecular mechanisms of SNS-032-induced cell death of AML cells are not yet fully understood. The aim of the study was to characterize the effects in vitro of SNS-032, used alone and in combination with an Akt inhibitor perifosine, against AML cells and to identify the mechanism involved.

RESULTS

SNS-032 significantly induced cytotoxicity in human AML cell lines and blasts from patients with newly diagnosed or relapsed AML. However, Kasumi-1 cells and some of leukemic samples (14.9%) from AML patients were resistant to SNS-032-mediated cell death. Western blot analysis showed that SNS-032 strongly inhibited the phosphorylation of mammalian target of rapamycin (mTOR) on Ser 2448 and Ser2481, and that removal of SNS-032 resulted in partial recovery of cell death and reactivation of phosphorylation of mTOR. Moreover, exogenous insulin-like growth factor-1 (IGF-1) did not reverse SNS-032-induced cell growth inhibition and downregualtion of phosphor-mTOR at Ser2448 and Ser2481 although slight suppression of IGF-1R expression was triggered by the agent. Furthermore, SNS-032 at a lower concentration (60-80 nM) enhanced AML cell cytotoxicity induced by perifosine, an Akt inhibitor. Importantly, SNS-032 treatment reduced colony formation ability of AML cells, which was significantly increased when two agents were combined. This combination therapy led to almost complete inhibition of Akt activity.

CONCLUSION

We conclude that SNS-032 might directly target mammalian target of rapamycin complex 1 (mTORC1)/mTORC2. Our results further provide a rationale for combining SNS-032 with perifosine for the treatment of AML.

Anticancer mechanisms and clinical application of alkylphospholipids

Synthetic alkylphospholipids (ALPs), such as edelfosine, miltefosine, perifosine, erucylphosphocholine and erufosine, represent a relatively new class of structurally related antitumor agents that act on cell membranes rather than on DNA. They selectively target proliferating (tumor) cells, inducing growth arrest and apoptosis, and are potent sensitizers of conventional chemo- and radiotherapy. ALPs easily insert in the outer leaflet of the plasma membrane and cross the membrane via an ATP-dependent CDC50a-containing 'flippase' complex (in carcinoma cells), or are internalized by lipid raft-dependent endocytosis (in lymphoma/leukemic cells). ALPs resist catabolic degradation, therefore accumulate in the cell and interfere with lipid-dependent survival signaling pathways, notably PI3K-Akt and Raf-Erk1/2, and de novo phospholipid biosynthesis. At the same time, stress pathways (e.g. stress-activated protein kinase/JNK) are activated to promote apoptosis. In many preclinical and clinical studies, perifosine was the most effective ALP, mainly because it inhibits Akt activity potently and consistently, also in vivo. This property is successfully exploited clinically in highly malignant tumors, such as multiple myeloma and neuroblastoma, in which a tyrosine kinase receptor/Akt pathway is amplified. In such cases, perifosine therapy is most effective in combination with conventional anticancer regimens or with rapamycin-type mTOR inhibitors, and may overcome resistance to these agents. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.