PTEN expression in non-small-cell lung cancer: evaluating its relation to tumor characteristics, allelic loss, and epigenetic alteration

An Updated Review on KRAS Mutation in Lung Cancer (NSCLC) and Its Effects on Human Health

The largest cause of cancer-related fatalities worldwide is lung cancer. In its early stages, lung cancer often exhibits no signs or symptoms. Its signs and symptoms often appear when the condition is advanced. The Kirsten rat sarcoma virus oncogene homolog is one of the most frequently mutated oncogenes found in non-small cell lung cancer. Patients who have these mutations may do worse than those who do not, in terms of survival. To understand the nuances in order to choose the best treatment options for each patient, including combination therapy and potential resistance mechanisms, given the quick development of pharmaceuticals, it is necessary to know the factors that might contribute to this disease. It has been observed that single nucleotide polymorphisms altering let-7 micro-RNA might impact cancer propensity. On the other hand, gefitinib fails to stop the oncogenic protein from directly interacting with phosphoinositide3-kinase, which may explain its resistance towards cancer cells. Additionally, Atorvastatin may be able to overpower gefitinib resistance in these cancer cells that have this mutation regardless of the presence of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha. De novo lipogenesis is also regulated by this virus. To overcome these effects, several targeted therapies have been proposed. One such therapy is to use inhibitors of focal adhesion kinases. When this is inhibited, viral oncogene mutant cancers are effectively stopped because it functions downstream of the virus. Mutant oncoproteins like epidermal growth factor receptor may depend on Heat Shock protein90 chaperones more frequently than they do on natural counterparts that make it more attractive therapeutic target for this virus. Inhibition of the phosphoinositide 3-kinase pathway is frequent in lung cancer, and fabrication of inhibitors against this pathway can also be an effective therapeutic strategy. Blocking programmed cell death ligand1 is another therapy that may help T cells to recognize and eliminate cancerous cells. This homolog is a challenging therapeutic target due to its complex structural makeup and myriad biological characteristics. Thanks to the unrelenting efforts of medical research, with the use of some inhibitors, immunotherapy, and other combination methods, this problem is currently expected to be overcome.

The potential role of circular RNAs -regulated PI3K signaling in non-small cell lung cancer: Molecular insights and clinical perspective

Non-small cell lung cancer (NSCLC), accounting for more than 80% of all cases, is the predominant form of lung cancer and the leading cause of cancer-related deaths worldwide. Significant progress has been made in diagnostic techniques, surgical interventions, chemotherapy protocols, and targeted therapies at the molecular level, leading to enhanced treatment outcomes in patients with NSCLC. Extensive evidence supports the use of circular RNAs (circRNAs), a specific category of naturally occurring non-coding small RNAs (ncRNAs), for the diagnosis, monitoring of treatment efficacy, and assessment of survival in NSCLC. CircRNAs have been identified to play significant roles in various aspects of cancer formation, either as tumor suppressors or tumor promoters, contributing to cancer development through several signaling pathways, including the phosphoinositide 3-kinases (PI3Ks) pathway. This pathway is well-established because of its regulatory role in essential cellular processes. CircRNAs regulate the PI3K/AKT pathway by targeting diverse cellular elements. This review aims to provide insight into the involvement of several circRNAs linked to the PI3K/AKT pathway in NSCLC.

PTEN regulates expression of its pseudogene in glioblastoma cells in DNA methylation-dependent manner

Glioblastoma (GBM) is the most aggressive and frequent type of primary brain cancer in adult patients. One of the key molecular features associated with GBM pathogenesis is the dysfunction of PTEN oncosuppressor. In addition to PTEN gene, humans and several primates possess processed PTEN pseudogene (PTENP1) that gives rise to long non-coding RNA lncPTENP1-S. Regulation and functions of PTEN and PTENP1 are highly interconnected, however, the exact molecular mechanism of how these two genes affect each other remains unclear. Here, we analyzed the methylation level of the CpG islands (CpGIs) in the promoter regions of PTEN and PTENP1 in patient-derived GBM neurospheres. We found that increased PTEN methylation corelates with decreased PTEN mRNA level. Unexpectedly, we showed the opposite trend for PTENP1. Using targeted methylation and demethylation of PTENP1 CpGI, we demonstrated that DNA methylation increases lncPTENP1-S expression in the presence of wild type PTEN protein but decreases lncPTENP1-S expression if PTEN protein is absent. Further experiments revealed that PTEN protein binds to PTENP1 promoter region and inhibits lncPTENP1-S expression if its CpGI is demethylated. Interestingly, we did not detect any effect of lncPTENP1-S on the level of PTEN mRNA, indicating that in GBM cells PTENP1 is a downstream target of PTEN rather than its upstream regulator. Finally, we studied the functions of lncPTENP1-S and demonstrated that it plays a pro-oncogenic role in GBM cells by upregulating the expression of cancer stem cell markers and decreasing cell adhesion.

Molecular mechanisms underlying the regulation of tumour suppressor genes in lung cancer

Tumour suppressor genes play a cardinal role in the development of a large array of human cancers, including lung cancer, which is one of the most frequently diagnosed cancers worldwide. Therefore, extensive studies have been committed to deciphering the underlying mechanisms of alterations of tumour suppressor genes in governing tumourigenesis, as well as resistance to cancer therapies. In spite of the encouraging clinical outcomes demonstrated by lung cancer patients on initial treatment, the subsequent unresponsiveness to first-line treatments manifested by virtually all the patients is inherently a contentious issue. In light of the aforementioned concerns, this review compiles the current knowledge on the molecular mechanisms of some of the tumour suppressor genes implicated in lung cancer that are either frequently mutated and/or are located on the chromosomal arms having high LOH rates (1p, 3p, 9p, 10q, 13q, and 17p). Our study identifies specific genomic loci prone to LOH, revealing a recurrent pattern in lung cancer cases. These loci, including 3p14.2 (FHIT), 9p21.3 (p16INK4a), 10q23 (PTEN), 17p13 (TP53), exhibit a higher susceptibility to LOH due to environmental factors such as exposure to DNA-damaging agents (carcinogens in cigarette smoke) and genetic factors such as chromosomal instability, genetic mutations, DNA replication errors, and genetic predisposition. Furthermore, this review summarizes the current treatment landscape and advancements for lung cancers, including the challenges and endeavours to overcome it. This review envisages inspired researchers to embark on a journey of discovery to add to the list of what was known in hopes of prompting the development of effective therapeutic strategies for lung cancer.

Coexpression of TP53, BIM, and PTEN Enhances the Therapeutic Efficacy of Non-Small-Cell Lung Cancer

For non-small-cell lung cancer (NSCLC), the ubiquitous occurrence of concurrent multiple genomic alterations poses challenges to single-gene therapy. To increase therapeutic efficacy, we used the branch-PCR method to develop a multigene nanovector, NP-TP53-BIM-PTEN, that carried three therapeutic gene expression cassettes for coexpression. NP-TP53-BIM-PTEN exhibited a uniform size of 104.8 ± 24.2 nm and high serum stability. In cell transfection tests, NP-TP53-BIM-PTEN could coexpress TP53, BIM, and PTEN in NCI-H1299 cells and induce cell apoptosis with a ratio of up to 94.9%. Furthermore, NP-TP53-BIM-PTEN also inhibited cell proliferation with a ratio of up to 42%. In a mouse model bearing an NCI-H1299 xenograft tumor, NP-TP53-BIM-PTEN exhibited a stronger inhibitory effect on the NCI-H1299 xenograft tumor than the other test vectors without any detectable side effects. These results exhibited the potential of NP-TP53-BIM-PTEN as an effective and safe multigene nanovector to enhance NSCLC therapy efficacy, which will provide a framework for genome therapy with multigene combinations.

Epigenetic regulation in lung cancer

Lung cancer is indeed a major cause of cancer-related deaths worldwide. The development of tumors involves a complex interplay of genetic, epigenetic, and environmental factors. Epigenetic mechanisms, including DNA methylation (DNAm), histone modifications, and microRNA expression, play a crucial role in this process. Changes in DNAm patterns can lead to the silencing of important genes involved in cellular functions, contributing to the development and progression of lung cancer. MicroRNAs and exosomes have also emerged as reliable biomarkers for lung cancer. They can provide valuable information about early diagnosis and treatment assessment. In particular, abnormal hypermethylation of gene promoters and its effects on tumorigenesis, as well as its roles in the Wnt signaling pathway, have been extensively studied. Epigenetic drugs have shown promise in the treatment of lung cancer. These drugs target the aberrant epigenetic modifications that are involved in the development and progression of the disease. Several factors have been identified as drug targets in non-small cell lung cancer. Recently, combination therapy has been discussed as a successful strategy for overcoming drug resistance. Overall, understanding the role of epigenetic mechanisms and their targeting through drugs is an important area of research in lung cancer treatment.

PTEN, PTENP1, microRNAs, and ceRNA Networks: Precision Targeting in Cancer Therapeutics

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a well characterised tumour suppressor, playing a critical role in the maintenance of fundamental cellular processes including cell proliferation, migration, metabolism, and survival. Subtle decreases in cellular levels of PTEN result in the development and progression of cancer, hence there is tight regulation of the expression, activity, and cellular half-life of PTEN at the transcriptional, post-transcriptional, and post-translational levels. PTENP1, the processed pseudogene of PTEN, is an important transcriptional and post-transcriptional regulator of PTEN. PTENP1 expression produces sense and antisense transcripts modulating PTEN expression, in conjunction with miRNAs. Due to the high sequence similarity between PTEN and the PTENP1 sense transcript, the transcripts possess common miRNA binding sites with the potential for PTENP1 to compete for the binding, or 'sponging', of miRNAs that would otherwise target the PTEN transcript. PTENP1 therefore acts as a competitive endogenous RNA (ceRNA), competing with PTEN for the binding of specific miRNAs to alter the abundance of PTEN. Transcription from the antisense strand produces two functionally independent isoforms (PTENP1-AS-α and PTENP1-AS-β), which can regulate PTEN transcription. In this review, we provide an overview of the post-transcriptional regulation of PTEN through interaction with its pseudogene, the cellular miRNA milieu and operation of the ceRNA network. Furthermore, its importance in maintaining cellular integrity and how disruption of this PTEN-miRNA-PTENP1 axis may lead to cancer but also provide novel therapeutic opportunities, is discussed. Precision targeting of PTENP1-miRNA mediated regulation of PTEN may present as a viable alternative therapy.

Modern Stereotactic Radiotherapy for Brain Metastases from Lung Cancer: Current Trends and Future Perspectives Based on Integrated Translational Approaches

Brain metastases (BMs) represent the most frequent metastatic event in the course of lung cancer patients, occurring in approximately 50% of patients with non-small-cell lung cancer (NSCLC) and in up to 70% in patients with small-cell lung cancer (SCLC). Thus far, many advances have been made in the diagnostic and therapeutic procedures, allowing improvements in the prognosis of these patients. The modern approach relies on the integration of several factors, such as accurate histological and molecular profiling, comprehensive assessment of clinical parameters and precise definition of the extent of intracranial and extracranial disease involvement. The combination of these factors is pivotal to guide the multidisciplinary discussion and to offer the most appropriate treatment to these patients based on a personalized approach. Focal radiotherapy (RT), in all its modalities (radiosurgery (SRS), fractionated stereotactic radiotherapy (SRT), adjuvant stereotactic radiotherapy (aSRT)), is the cornerstone of BM management, either alone or in combination with surgery and systemic therapies. We review the modern therapeutic strategies available to treat lung cancer patients with brain involvement. This includes an accurate review of the different technical solutions which can be exploited to provide a "state-of-art" focal RT and also a detailed description of the systemic agents available as effective alternatives to SRS/SRT when a targetable molecular driver is present. In addition to the validated treatment options, we also discuss the future perspective for focal RT, based on emerging clinical reports (e.g., SRS for patients with many BMs from NSCLC or SRS for BMs from SCLC), together with a presentation of innovative and promising findings in translational research and the combination of novel targeted agents with SRS/SRT.

Targeting Cell Signaling Pathways in Lung Cancer by Bioactive Phytocompounds

Lung cancer is a heterogeneous group of malignancies with high incidence worldwide. It is the most frequently occurring cancer in men and the second most common in women. Due to its frequent diagnosis and variable response to treatment, lung cancer was reported as the top cause of cancer-related deaths worldwide in 2020. Many aberrant signaling cascades are implicated in the pathogenesis of lung cancer, including those involved in apoptosis (B cell lymphoma protein, Bcl-2-associated X protein, first apoptosis signal ligand), growth inhibition (tumor suppressor protein or gene and serine/threonine kinase 11), and growth promotion (epidermal growth factor receptor/proto-oncogenes/phosphatidylinositol-3 kinase). Accordingly, these pathways and their signaling molecules have become promising targets for chemopreventive and chemotherapeutic agents. Recent research provides compelling evidence for the use of plant-based compounds, known collectively as phytochemicals, as anticancer agents. This review discusses major contributing signaling pathways involved in the pathophysiology of lung cancer, as well as currently available treatments and prospective drug candidates. The anticancer potential of naturally occurring bioactive compounds in the context of lung cancer is also discussed, with critical analysis of their mechanistic actions presented by preclinical and clinical studies.

Targeted therapy based on ubiquitin-specific proteases, signalling pathways and E3 ligases in non-small-cell lung cancer

Lung cancer is one of the most common malignant tumours worldwide, with the highest mortality rate. Approximately 1.6 million deaths owing to lung cancer are reported annually; of which, 85% of deaths occur owing to non-small-cell lung cancer (NSCLC). At present, the conventional treatment methods for NSCLC include radiotherapy, chemotherapy, targeted therapy and surgery. However, drug resistance and tumour invasion or metastasis often lead to treatment failure. The ubiquitin–proteasome pathway (UPP) plays an important role in the occurrence and development of tumours. Upregulation or inhibition of proteins or enzymes involved in UPP can promote or inhibit the occurrence and development of tumours, respectively. As regulators of UPP, ubiquitin-specific proteases (USPs) primarily inhibit the degradation of target proteins by proteasomes through deubiquitination and hence play a carcinogenic or anticancer role. This review focuses on the role of USPs in the occurrence and development of NSCLC and the potential of corresponding targeted drugs, PROTACs and small-molecule inhibitors in the treatment of NSCLC.

The potential application of branch-PCR assembled PTEN gene nanovector in lung cancer gene therapy

Gene therapy offers an alternative and promising avenue to lung cancer treatment. Here, we used dibenzocyclooctyne (DBCO)-branched primers to construct a kind of PTEN gene nanovector (NP-PTEN) through branch-PCR. NP-PTEN showed the nanoscale structure with the biocompatible size (84.7 ± 11.2 nm) and retained the improved serum stability compared to linear DNA. When transfected into NCI-H1299 cancer cells, NP-PTEN could overexpress PTEN protein to restore PTEN function through the deactivation of PI3K-AKT-mTOR signaling pathway to inhibit cell proliferation and induce cell apoptosis. The apoptosis rate of NCI-H1299 cancer cells could reach up to 54.5% ± 4.6% when the transfection concentration of NP-PTEN was 4.0 μg/mL. In mice bearing NCI-H1299 tumor xenograft intratumorally administrated with NP-PTEN, the average tumor volume and tumor weight was separately reduced by 61.7% and 63.9% compared with the PBS group on the 18 th day of administration. The anticancer efficacy of NP-PTEN in NCI-H1299 tumor xenograft suggested the promising therapeutic potential of this branch-PCR assembled PTEN gene nanovectors in lung cancer gene therapy and also provided more opportunities to introduce two or more tumor suppressor genes as the all-in-one gene nanovectors for multiple gene-based cancer gene therapy.

Treating non-small cell lung cancer by targeting the PI3K signaling pathway

ABSTRACT

The phosphosphatidylinositol-3-kinase (PI3K) signaling pathway is one of the most important intracellular signal transduction pathways affecting cell functions, such as apoptosis, translation, metabolism, and angiogenesis. Lung cancer is a malignant tumor with the highest morbidity and mortality rates in the world. It can be divided into two groups, non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). NSCLC accounts for >85% of all lung cancers. There are currently many clinical treatment options for NSCLC; however, traditional methods such as surgery, chemotherapy, and radiotherapy have not been able to provide patients with good survival benefits. The emergence of molecular target therapy has improved the survival and prognosis of patients with NSCLC. In recent years, there have been an increasing number of studies on NSCLC and PI3K signaling pathways. Inhibitors of various parts of the PI3K pathway have appeared in various phases of clinical trials with NSCLC as an indication. This article focuses on the role of the PI3K signaling pathway in the occurrence and development of NSCLC and summarizes the current clinical research progress and possible development strategies.

The Double-Edged Sword of SIRT3 in Cancer and Its Therapeutic Applications

Reprogramming of cellular energy metabolism is considered an emerging feature of cancer. Mitochondrial metabolism plays a crucial role in cancer cell proliferation, survival, and metastasis. As a major mitochondrial NAD⁺-dependent deacetylase, sirtuin3 (SIRT3) deacetylates and regulates the enzymes involved in regulating mitochondrial energy metabolism, including fatty acid oxidation, the Krebs cycle, and the respiratory chain to maintain metabolic homeostasis. In this article, we review the multiple roles of SIRT3 in various cancers, and systematically summarize the recent advances in the discovery of its activators and inhibitors. The roles of SIRT3 vary in different cancers and have cell- and tumor-type specificity. SIRT3 plays a unique function by mediating interactions between mitochondria and intracellular signaling. The critical functions of SIRT3 have renewed interest in the development of small molecule modulators that regulate its activity. Delineation of the underlying mechanism of SIRT3 as a critical regulator of cell metabolism and further characterization of the mitochondrial substrates of SIRT3 will deepen our understanding of the role of SIRT3 in tumorigenesis and progression and may provide novel therapeutic strategies for cancer targeting SIRT3.

The PI3K/Akt/mTOR pathway in lung cancer; oncogenic alterations, therapeutic opportunities, challenges, and a glance at the application of nanoparticles

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Lung cancer is the most common and deadliest human malignancies.

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The alterations of PI3K/Akt/mTOR pathway are related to lung cancer progression.

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PI3K axis regulates proliferation, apoptosis, metastasis, and EMT of lung cancer.

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Agents inhibiting components of PI3K axis diminish lung tumor growth and invasion.

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Low efficacy and off-target toxicity could be improved by nanoparticle application.

Lung cancer is the leading cause of cancer-related mortality worldwide. Although the PI3K/Akt/mTOR signaling pathway has recently been considered as one of the most altered molecular pathways in this malignancy, few articles reviewed the task. In this review, we aim to summarize the original data obtained from international research laboratories on the oncogenic alterations in each component of the PI3K/Akt/mTOR pathway in lung cancer. This review also responds to questions on how aberrant activation in this axis contributes to uncontrolled growth, drug resistance, sustained angiogenesis, as well as tissue invasion and metastatic spread. Besides, we provide a special focus on pharmacologic inhibitors of the PI3K/Akt/mTOR axis, either as monotherapy or in a combined-modal strategy, in the context of lung cancer. Despite promising outcomes achieved by using these agents, however, the presence of drug resistance as well as treatment-related adverse events is the other side of the coin. The last section allocates a general overview of the challenges associated with the inhibitors of the PI3K pathway in lung cancer patients. Finally, we comment on the future research aspects, especially in which nano-based drug delivery strategies might increase the efficacy of the therapy in this malignancy.

Regulation of the tumor suppressor PTEN in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a subtype of breast cancer (BCa) in which estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2) are not expressed. Although TNBC cases account for approximately 15% of all BCa cases, TNBC patients' prognosis is poor compared with that of other BCa subtypes. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) plays an important role in cell proliferation and migration by negatively regulating the PI3K/Akt pathway. PTEN is one of the most commonly inactivated tumor suppressors in BCa. PTEN inactivity is associated with larger tumor sizes, multiple lymph node metastases, and an aggressive triple-negative phenotype. This review primarily focuses on two key points: (1) PTEN and its function. (2) The regulation of tumor suppressor PTEN in TNBC. We provide a summary of genomic alterations of PTEN in BCa. We further discuss the transcriptional regulation of PTEN and how PTEN is regulated by posttranscription and posttranslational modification, as well as by protein interactions. Finally, we discuss the perspectives of the PTEN protein in TNBC.

The deubiquitinase USP10 restores PTEN activity and inhibits non-small cell lung cancer cell proliferation

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) protein is a key player in tumorigenesis of non–small cell lung cancer (NSCLC) and was recently found to be inactivated by tripartite motif containing 25 (TRIM25)–mediated K63-linked polyubiquitination. However, the deubiquitinase (Dub) coordinate TRIM25 in PTEN ubiquitination is still elusive. In the present study, we found that this K63-linked polyubiquitination could be ablated by the ubiquitin-specific protease 10 (USP10) in a screen against a panel of Dubs. We found using coimmununoprecipitation/immunoblotting that USP10 interacted with PTEN and reduced the K63-linked polyubiquitination of PTEN mediated by TRIM25 in NSCLC cells. Moreover, USP10, but not its inactive C424A deubiquitinating mutant or other Dubs, abolished PTEN from K63-linked polyubiquitination mediated by TRIM25. In contrast to TRIM25, USP10 restored PTEN phosphatase activity and reduced the production of the secondary messenger phosphatidylinositol-3,4,5-trisphosphate, thereby inhibiting AKT/mammalian target of rapamycin progrowth signaling transduction in NSCLC cells. Moreover, USP10 was downregulated in NSCLC cell lines and primary tissues, whereas TRIM25 was upregulated. Consistent with its molecular activity, re-expression of USP10 suppressed NSCLC cell proliferation and migration, whereas knockout of USP10 promoted NSCLC cell proliferation and migration. In conclusion, the present study demonstrates that USP10 coordinates TRIM25 to modulate PTEN activity. Specifically, USP10 activates PTEN by preventing its K63-linked polyubiquitination mediated by TRIM25 and suppresses the AKT/mammalian target of rapamycin signaling pathway, thereby inhibiting NSCLC proliferation, indicating that it may be a potential drug target for cancer treatment.

New Scope of Targeted Therapies in Lung Carcinoma

Lung cancer (LC) is the leading cause of cancer deaths worldwide. Recent research has also shown LC as a genomic disease, causing somatic mutations in patients. Tests related to mutational analysis and genome profiles have lately expanded significantly in the genetics/genomics field of LC. This review summarizes the current knowledge about different signalling pathways of LC based on the clinical impact of molecular targets. It describes the main molecular pathways and changes involved in the development, progression, and cellular breakdown of LC and the molecular changes. This review focuses on approved and targeted experimental therapies such as immunotherapy and clinical trials that examine the different targeted approaches to treating LC. We aimto clarify the differences in the extent of various genetic mutations in several areas for LC patients. Targeted molecular therapies for LC can be continued with advanced racial differences in genetic changes, which have a significant impact on the choice of drug treatment and our understanding of the profile of drug susceptibility/resistance. The most relevant genes described in this review are EGFR, KRAS, MET, BRAF, PIK3CA, STK11, ERBB3, PTEN, and RB1. Combined research efforts in this field are required to understand the genetic difference in LC outcomes in the future.

Natural killer cells and cytotoxic T lymphocytes are required to clear solid tumor in a patient-derived xenograft

Existing patient-derived xenograft (PDX) mouse models of solid tumors lack a fully tumor donor-matched, syngeneic, and functional immune system. We developed a model that overcomes these limitations by engrafting lymphopenic recipient mice with a fresh, undisrupted piece of solid tumor, whereby tumor-infiltrating lymphocytes (TILs) persisted in the recipient mice for several weeks. Successful tumor engraftment was achieved in 83% to 89% of TIL-PDX mice, and these were seen to harbor exhausted immuno-effector as well as functional immunoregulatory cells persisting for at least 6 months postengraftment. Combined treatment with interleukin-15 stimulation and immune checkpoint inhibition resulted in complete or partial tumor response in this model. Further, depletion of cytotoxic T lymphocytes and/or natural killer cells before combined immunotherapy revealed that both cell types were required for maximal tumor regression. Our TIL-PDX model provides a valuable resource for powerful mechanistic and therapeutic studies in solid tumors.

Efficacy of immunotherapy in KRAS-mutant non-small-cell lung cancer with comutations

KRAS-mutant non-small-cell lung cancer is the most common molecular driver of lung adenocarcinoma in western populations. No KRAS specific therapy has been approved by the US FDA until 2021. Despite significant heterogeneity in comutations, patients typically receive single-agent immunotherapy or chemoimmunotherapy as standard first-line therapy. It is unclear whether KRAS mutations predict outcomes with immunotherapy; however, there is emerging data suggesting improved outcomes in patients with a TP53 comutation and worse outcomes in patients with a STK11/LKB1 or KEAP1 comutation.

Integrating endobronchial ultrasound bronchoscopy with molecular testing of immunotherapy biomarkers in non-small cell lung cancer

Immunotherapy has transformed treatment of advanced non-small-cell lung cancer (NSCLC) patients leading to remarkable long-term survival benefit. However, only about 20% of advanced NSCLC patients typically respond to immune checkpoint inhibitors (ICIs) that target the PD-1/PD-L1 pathway. The only validated biomarker for ICI therapy is the PD-L1 immunohistochemistry (IHC) test, which is considered an imperfect assay due to several variables including availability and integrity of tumour tissue, variability in staining/scoring techniques and heterogeneity in PD-L1 protein expression within and across tumour biopsies. Herein, we discuss integrating minimally invasive EBUS bronchoscopy procedures with novel molecular approaches to improve accuracy and sensitivity of PD-L1 testing. EBUS guided bronchoscopy facilitates repeated sampling of tumour tissue to increase the probability of detecting PD-L1 positive tumours. Since intra-tumoural PD-L1 (CD274) copy number is reported to be less heterogeneous than PD-L1 protein detection, quantifying PD-L1 transcript levels may increase detection of PD-L1 positive tumours. PD-L1 transcript levels show excellent concordance with PD-L1 IHC scoring and multiplex digital droplet PCR (ddPCR) assays that quantify absolute PD-L1 transcript copy number have been developed. ddPCR can also be automated for high throughput detection of low abundant variants with excellent sensitivity and accuracy to improve the broader application of diagnostic cut-off values. Optimizing diagnostic workflows that integrate optimal EBUS bronchoscopy procedures with emerging molecular ICI biomarker assays may improve the selection criteria for ICI therapy benefit.

Clear Cell Renal Carcinoma: MicroRNAs With Efficacy in Preclinical In Vivo Models

In order to identify new targets and treatment modalities for clear cell renal carcinoma, we surveyed the literature with respect to microRNAs involved in this disease. In this review, we have focused on up- and down-regulated miRs which mediate efficacy in preclinical clear-cell renal carcinoma-related in vivo models. We have identified 10 up-regulated and 33 down-regulated micro-RNAs according to this criterion. As proof-of-concept, micro-RNAs interfering with VEGF (miR-205p) and mTOR (mir-99a) pathways, which are modulated by approved drugs for this disease, have been identified. miRs targeting hypoxia induced factor-2α (HIF-2α) (miR-145), E3 ubiquitinylases speckle-type POZ protein (SPOP) (miR 520/372/373) and casitas B-lineage lymphoma (CBL) (miR-200a-3p), interfere with druggable targets. Further identified miRs interfere with cell-cycle dependent kinases, such as CDK2 (miR-200c), CDK4, 6 (miR-1) and CDK4, 9 (206c). Transmembrane receptor Ral interacting protein of 76 kD (RLIP76), targeted by mir-137, has emerged as another important target for ccRCC. Additional miRs and their targets merrying further preclinical validation are discussed.

Thymoquinone Is a Multitarget Single Epidrug That Inhibits the UHRF1 Protein Complex

Silencing of tumor suppressor genes (TSGs) through epigenetic mechanisms, mainly via abnormal promoter DNA methylation, is considered a main mechanism of tumorigenesis. The abnormal DNA methylation profiles are transmitted from the cancer mother cell to the daughter cells through the involvement of a macromolecular complex in which the ubiquitin-like containing plant homeodomain (PHD), and an interesting new gene (RING) finger domains 1 (UHRF1), play the role of conductor. Indeed, UHRF1 interacts with epigenetic writers, such as DNA methyltransferase 1 (DNMT1), histone methyltransferase G9a, erasers like histone deacetylase 1 (HDAC1), and functions as a hub protein. Thus, targeting UHRF1 and/or its partners is a promising strategy for epigenetic cancer therapy. The natural compound thymoquinone (TQ) exhibits anticancer activities by targeting several cellular signaling pathways, including those involving UHRF1. In this review, we highlight TQ as a potential multitarget single epidrug that functions by targeting the UHRF1/DNMT1/HDAC1/G9a complex. We also speculate on the possibility that TQ might specifically target UHRF1, with subsequent regulatory effects on other partners.

Human Schlafen 5 Inhibits Proliferation and Promotes Apoptosis in Lung Adenocarcinoma via the PTEN/PI3K/AKT/mTOR Pathway

BACKGROUND

Human Schlafen 5 (SLFN5) is reported to inhibit or promote the proliferation of several specific types of cancer cells by our lab and other researchers. We are curious about its implications in lung adenocarcinoma (LUAC), a malignant tumor with a high incidence rate and high mortality.

METHOD

Lentiviral stable transfections of SLFN5-specific shRNA for knockdown and SLFN5 full-length coding sequence for overexpression were performed in LUAC cell for proliferation analysis in vitro and in vivo in nude mice. Clinical LUAC samples were collected for immunohistochemical analysis of SLFN5 protein levels.

RESULTS

We found that knockdown of endogenous SLFN5 upregulates cancer cell proliferation while inhibiting apoptosis. Besides, SLFN5 inhibition on proliferation was also observed in a nude mouse xenograft model. In contrast, overexpression of exogenous SLFN5 inhibited cell proliferation in vitro and in vivo and promoted apoptosis. As to the signaling pathway, we found phosphatase and tensin homolog on chromosome 10 (PTEN) was positively regulated by SLFN5, while its downstream signaling pathway AKT/mammalian target of rapamycin (mTOR) was inhibited. Moreover, compared with adjacent normal tissues, SLFN5 protein levels were markedly decreased in lung adenocarcinoma tissues. In conclusion, these suggest that human SLFN5 plays inhibitory roles in LUAC progression through the PTEN/PI3K/AKT/mTOR pathway, providing a potential target for developing drugs for lung cancer therapy in the future.

LINC01089 functions as a ceRNA for miR-152-3p to inhibit non-small lung cancer progression through regulating PTEN

Background

Long non-coding RNAs (lncRNAs) have been reported to exert crucial functions in regulating the progression of human cancers. However, the function and mechanism of long intergenic non-protein coding RNA 01089 (LINC01089) in non-small cell lung cancer (NSCLC) have not been revealed.

Methods

The expression level of LINC01089, microRNA (miRNA, miR)-152-3p and phosphatase and tensin homolog deleted onc hromosome ten (PTEN) mRNA was detected by quantitative real-time PCR (qRT-PCR). After gain-of-function and loss-of-function models were established with NSCLC cell lines, the proliferation, migration and invasion of NSCLC cells were detected by cell counting kit-8 (CCK-8) assay, scratch healing assay, Transwell assay, respectively. Dual luciferase reporter assay was employed to validate the binding relationship between miR-152-3p and LINC01089 or the 3’UTR of PTEN. Western blot was used to detect PTEN expression in NSCLC cells after LINC01089 and miR-152-3p were selectively modulated.

Results

LINC01089 was down-regulated in NSCLC tissues and cells. Functional experiments showed that knockdown of LINC01089 could promote the proliferation, migration and invasion of NSCLC cells, while over-expression of LINC01089 had the opposite effects. miR-152-3p was identified as a functional target for LIN01089, and miR-152-3p could reverse the function of LINC01089. Additionally, LINC01089 could up-regulate the expression level of PTEN via repressing miR-152-3p.

Conclusions

Down-regulation of LINC01089 promoted the progression of NSCLC through regulating miR-152-3p/PTEN axis.

Head to head evaluation of second generation ALK inhibitors brigatinib and alectinib as first-line treatment for ALK+ NSCLC using an in silico systems biology-based approach

Around 3-7% of patients with non-small cell lung cancer (NSCLC), which represent 85% of diagnosed lung cancers, have a rearrangement in the ALK gene that produces an abnormal activity of the ALK protein cell signaling pathway. The developed ALK tyrosine kinase inhibitors (TKIs), such as crizotinib, ceritinib, alectinib, brigatinib and lorlatinb present good performance treating ALK+ NSCLC, although all patients invariably develop resistance due to ALK secondary mutations or bypass mechanisms. In the present study, we compare the potential differences between brigatinib and alectinib's mechanisms of action as first-line treatment for ALK+ NSCLC in a systems biology-based in silico setting. Therapeutic performance mapping system (TPMS) technology was used to characterize the mechanisms of action of brigatinib and alectinib and the impact of potential resistances and drug interferences with concomitant treatments. The analyses indicate that brigatinib and alectinib affect cell growth, apoptosis and immune evasion through ALK inhibition. However, brigatinib seems to achieve a more diverse downstream effect due to a broader cancer-related kinase target spectrum. Brigatinib also shows a robust effect over invasiveness and central nervous system metastasis-related mechanisms, whereas alectinib seems to have a greater impact on the immune evasion mechanism. Based on this in silico head to head study, we conclude that brigatinib shows a predicted efficacy similar to alectinib and could be a good candidate in a first-line setting against ALK+ NSCLC. Future investigation involving clinical studies will be needed to confirm these findings. These in silico systems biology-based models could be applied for exploring other unanswered questions.

The Role of mTOR Signaling as a Therapeutic Target in Cancer

The aim of this review was to summarize current available information about the role of phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling in cancer as a potential target for new therapy options. The mTOR and PI3K/AKT/mTORC1 (mTOR complex 1) signaling are critical for the regulation of many fundamental cell processes including protein synthesis, cell growth, metabolism, survival, catabolism, and autophagy, and deregulated mTOR signaling is implicated in cancer, metabolic dysregulation, and the aging process. In this review, we summarize the information about the structure and function of the mTOR pathway and discuss the mechanisms of its deregulation in human cancers including genetic alterations of PI3K/AKT/mTOR pathway components. We also present recent data regarding the PI3K/AKT/mTOR inhibitors in clinical studies and the treatment of cancer, as well the attendant problems of resistance and adverse effects.

Methylation of the PTENP1 pseudogene as potential epigenetic marker of age-related changes in human endometrium

The processed pseudogene PTENP1 is involved in the regulation of the expression of the PTEN and acts as a tumor suppressor in many types of malignances. In our previous study we showed that PTENP1 methylation is present not only in tumor, but also in normal endometrium tissues of women over 45 years old. Here we used methylation-specific PCR to analyze methylation status of CpG island located near promoter region of PTENP1 in malignant and non-malignant endometrium tissues collected from 236 women of different age groups. To confirm our results, we also analyzed RNA sequencing and microarray data from 431 women with endometrial cancer from TCGA database. We demonstrated that methylation of PTENP1 is significantly increased in older patients. We also found an age-dependent increase in the level of PTENP1 expression in endometrial tissue. According to our data, PTENP1 methylation elevates the level of the pseudogene sense transcript. In turn, a high level of this transcript correlates with a more favorable prognosis in endometrial cancer. The data obtained suggested that PTENP1 methylation is associated with age-related changes in normal and hyperplastic endometrial tissues. We assumed that age-related increase in PTENP1 methylation and subsequent elevation of its expression may serve as a protective mechanism aimed to prevent malignant transformation of endometrial tissue in women during the perimenopause, menopause, and postmenopause periods.

Primary and Acquired Resistance to Immunotherapy in Lung Cancer: Unveiling the Mechanisms Underlying of Immune Checkpoint Blockade Therapy

After several decades without maintained responses or long-term survival of patients with lung cancer, novel therapies have emerged as a hopeful milestone in this research field. The appearance of immunotherapy, especially immune checkpoint inhibitors, has improved both the overall survival and quality of life of patients, many of whom are diagnosed late when classical treatments are ineffective. Despite these unprecedented results, a high percentage of patients do not respond initially to treatment or relapse after a period of response. This is due to resistance mechanisms, which require understanding in order to prevent them and develop strategies to overcome them and increase the number of patients who can benefit from immunotherapy. This review highlights the current knowledge of the mechanisms and their involvement in resistance to immunotherapy in lung cancer, such as aberrations in tumor neoantigen burden, effector T-cell infiltration in the tumor microenvironment (TME), epigenetic modulation, the transcriptional signature, signaling pathways, T-cell exhaustion, and the microbiome. Further research dissecting intratumor and host heterogeneity is necessary to provide answers regarding the immunotherapy response and develop more effective treatments for lung cancer.

Long Non-Coding RNAs as Regulators of Interactions between Cancer-Associated Fibroblasts and Cancer Cells in the Tumor Microenvironment

Long non-coding RNAs (lncRNAs) regulate diverse physiological and pathological processes via post-transcriptional, post-translational, and epigenetic mechanisms. They are also involved in tumor initiation, progression, and metastasis by functioning as key players in the tumor microenvironment. Cancer-associated fibroblasts (CAFs) promote tumor initiation, progression, metastasis, drug resistance, and immunosuppression, which can be modulated by lncRNAs. LncRNAs regulate the intrinsic properties of CAFs or cancer cells intracellularly or function extracellularly through exosomal secretion. In-depth studies on the mechanisms of lncRNA functions will enable their clinical use as diagnosis/prognosis markers and therapeutic targets in cancer treatment.

Expression and clinical significance of microRNA-21, PTEN and p27 in cancer tissues of patients with non-small cell lung cancer

Expression and clinical significance of micro-RNA-21, PTEN and p27 in cancer tissue of patients with non-small cell lung cancer (NSCLC) were investigated. In this study, cancer tissue and adjacent tissue specimens from 230 patients with NSCLC were collected from thoracic surgery department in Hubei Cancer Hospital from March 2010 to February 2016. The expression of miRNA-21, PTEN and p27 in cancer tissue and adjacent tissue of patients with NSCLC was detected by RT-PCR. Combined with clinical information, the correlation among miRNA-21, PTEN, p27 and clinical features of NSCLC was analyzed. The expression of miRNA-21, PTEN, p27 in NSCLC was significantly lower than that in adjacent tissue by RT-PCR (P<0.05). There was no significant difference in age, sex and course of disease (P>0.050), but there were differences in smoking, lymph node metastasis, TNM stage and differentiation degree classification (P<0.050). By comparing the 3-year survival rate in the group with high and low expression of miRNA-21, PTEN and p27, it was found that the 36-month survival rate of patients with high expression of miRNA-21 was 85.19% (P<0.05), and of patients with low expression of miRNA-21 it was 95.90% (P<0.05). The 36-month survival rate of patients with high expression of PTEN was 85.59% (P<0.05), of patients with low expression of PTEN it was 94.96% (P<0.05) and in patients with high expression of p27 it was 84.91% (P<0.05). The 36-month survival rate of patients with low expression of p27 was 94.35% (P<0.05). The survival rates of miRNA-21, PTEN and p27 low expression groups were significantly higher than those of high expression groups (P<0.05). In conclusion, the expression of miRNA-21, PTEN and p271 in cancer tissue of NSCLC patients was low. The three indexes have good diagnostic efficacy based on ROC curve analysis, and are expected to be excellent indexes for early clinical diagnosis and prognosis of NSCLC.

Investigation of PTEN promoter methylation in ameloblastoma

Background

Phosphatase and tensin homolog (PTEN) acts as a tumor suppressor gene. Inactivation of PTEN has been reported in various types of cancers. PTEN promoter methylation possibly underlies PTEN inactivation, which results in tumorigenesis. The aim of this study was to investigate whether PTEN promoter methylation contributes to PTEN inactivation in ameloblastoma and its associated protein expression.

Material and Methods

In total, 20 fresh-frozen ameloblastoma samples were evaluated for PTEN promoter methylation using methylation-specific polymerase chain reaction (MS-PCR). A subset of 10 paraffin-embedded ameloblastoma samples was examined for PTEN expression through immunohistochemistry. Four primary cultured ameloblastoma cells were investigated for PTEN promoter methylation and PTEN transcriptional expression via reverse transcription PCR.

Results

PTEN promoter methylation was detected in 65% (13/20) of the ameloblastoma samples. Of 10 ameloblastoma samples, 4 exhibited reduced PTEN expression. Of 5 samples with methylated PTEN, 3 (60%) were associated with loss of PTEN expression. However, PTEN expression was detected in 4 (80%) of 5 samples with unmethylated PTEN. In addition, 3 (75%) of 4 primary ameloblastoma cell cultures exhibited an inverse correlation between PTEN promoter methylation and PTEN transcription level.

Conclusions

PTEN promoter methylation is found in a number of ameloblastomas but not significantly correlated with loss of PTEN expression. Genetic or epigenetic mechanisms other than PTEN promoter methylation may contribute to PTEN inactivation in ameloblastoma tumor cells.

Key words:PTEN, promoter methylation, ameloblastoma.

The Complex Landscape of PTEN mRNA Regulation

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a key tumor suppressor in the development and progression of different tumor types. Emerging data indicate that small reductions in PTEN protein levels can promote cancer. PTEN protein levels are tightly controlled by a plethora of mechanisms beginning with epigenetic and transcriptional regulation and ending with control of protein synthesis and stability. PTEN messenger RNA (mRNA) is also subject to exquisite regulation by microRNAs, coding and long noncoding RNAs, and RNA-binding proteins. Additionally, PTEN mRNA is markedly influenced by alternative splicing and variable polyadenylation. Herein we provide a synoptic description of the current understanding of the complex regulatory landscape of PTEN mRNA regulation including several specific processes that modulate its stability and expression, in the context of PTEN loss-associated cancers.

Toward Systems Pathology for PTEN Diagnostics

Germline alterations of the tumor suppressor PTEN have been extensively characterized in patients with PTEN hamartoma tumor syndromes, encompassing subsets of Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome, Proteus and Proteus-like syndromes, as well as autism spectrum disorder. Studies have shown an increase in the risk of developing specific cancer types in the presence of a germline PTEN mutation. Furthermore, outside of the familial setting, somatic variants of PTEN occur in numerous malignancies. Here we introduce and discuss the prospect of moving toward a systems pathology approach for PTEN diagnostics, incorporating clinical and molecular pathology data with the goal of improving the clinical management of patients with a PTEN mutation. Detection of a germline PTEN mutation can inform cancer surveillance and in the case of somatic mutation, have value in predicting disease course. Given that PTEN functions in the PI3K/AKT/mTOR pathway, identification of a PTEN mutation may highlight new therapeutic opportunities and/or inform therapeutic choices.

Exosomes derived from normal human bronchial epithelial cells down-regulate proliferation and migration of hydroquinone-transformed malignant recipient cells via up-regulating PTEN expression

The gene encoding the tumor suppressor, phosphatase and tensin homolog (PTEN), located on chromosome 10, is frequently expressed at low levels in various tumors, resulting in the stimulation of cell proliferation and migration. However, the role of exosomal PTEN in cell-cell communication during the progress of benzene-induced carcinogenesis remains unclear. The goal of this study was to explore whether exosomes derived from normal human bronchial epithelial cells (16HBE) could transmit PTEN to hydroquinone-transformed malignant recipient cells (16HBE-t) and its possible effects on cell proliferation and migration. Consistent with PTEN expression being down-regulated in transformed cells, we found that its expression was significantly decreased in 16HBE-t relative to 16HBE cells and that purified exosomes secreted by 16HBE, up-regulated PTEN levels in recipient 16HBE-t cells. Thus, down-regulating their proliferation and migration. Further, when exosomes derived from 16HBE cells that had been treated with the PTEN inhibitor SF1670, were incubated with recipient 16HBE-t cells, they exhibited decreased PTEN levels, with a corresponding increase in their proliferation and migration. In conclusion, our study demonstrates that exosomes derived from 16HBE cells can down-regulate proliferation and migration of recipient 16HBE-t cells via transferring PTEN.

Targeting the PI3K/Akt/mTOR pathway in non-small cell lung cancer (NSCLC)

The traditional classification of lung cancer into small cell lung cancer and non‐small cell lung cancer (NSCLC) has been transformed with the increased understanding of the molecular alterations and genomic biomarkers that drive the development of lung cancer. Increased activation of the phosphatidylinositol 3‐kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) pathway leads to numerous hallmarks of cancer and this pathway represents an attractive target for novel anticancer therapies. In NSCLC, the PI3K/Akt/mTOR pathway has been heavily implicated in both tumorigenesis and the progression of disease. A number of specific inhibitors of PI3K, Akt and mTOR are currently under development and in various stages of preclinical investigation and in early phase clinical trials for NSCLC. Early evidence has yielded disappointing results. Clinical trials, however, have been performed on predominantly molecularly unselected populations, and patient enrichment strategies using high‐precision predictive biomarkers in future trials will increase the likelihood of success. A greater understanding of the underlying molecular biology including epigenetic alterations is also crucial to allow for the detection of appropriate biomarkers and guide combination approaches.

Targeting non-small cell lung cancer: driver mutation beyond epidermal growth factor mutation and anaplastic lymphoma kinase fusion

The identification of driver mutations in epidermal growth factor receptor, anaplastic lymphoma kinase, the BRAF and ROS1 genes and subsequent successful clinical development of kinase inhibitors not only significantly improves clinical outcomes but also facilitates the discovery of other novel driver mutations in non-small cell lung cancer. These driver mutations can be categorized into mutations in or near the kinase domain, gene amplification or fusion. In this review, BRAF V600E, EGFR and HER-2 exon 20 mutation, FGFR1-4, K-RAS, MET, neuregulin-1, NRTK, PI3K/AKT/mTOR, RET and ROS1 gene aberration and their therapeutics will be discussed.

Mechanistic Understanding of Curcumin's Therapeutic Effects in Lung Cancer

Lung cancer is among the most common cancers with a high mortality rate worldwide. Despite the significant advances in diagnostic and therapeutic approaches, lung cancer prognoses and survival rates remain poor due to late diagnosis, drug resistance, and adverse effects. Therefore, new intervention therapies, such as the use of natural compounds with decreased toxicities, have been considered in lung cancer therapy. Curcumin, a natural occurring polyphenol derived from turmeric (Curcuma longa) has been studied extensively in recent years for its therapeutic effects. It has been shown that curcumin demonstrates anti-cancer effects in lung cancer through various mechanisms, including inhibition of cell proliferation, invasion, and metastasis, induction of apoptosis, epigenetic alterations, and regulation of microRNA expression. Several in vitro and in vivo studies have shown that these mechanisms are modulated by multiple molecular targets such as STAT3, EGFR, FOXO3a, TGF-β, eIF2α, COX-2, Bcl-2, PI3KAkt/mTOR, ROS, Fas/FasL, Cdc42, E-cadherin, MMPs, and adiponectin. In addition, limitations, strategies to overcome curcumin bioavailability, and potential side effects as well as clinical trials were also reviewed.

Precise Immunodetection of PTEN Protein in Human Neoplasia

PTEN is a major tumor-suppressor protein whose expression and biological activity are frequently diminished in sporadic or inherited cancers. PTEN gene deletion or loss-of-function mutations favor tumor cell growth and are commonly found in clinical practice. In addition, diminished PTEN protein expression is also frequently observed in tumor samples from cancer patients in the absence of PTEN gene alterations. This makes PTEN protein levels a potential biomarker parameter in clinical oncology, which can guide therapeutic decisions. The specific detection of PTEN protein can be achieved by using highly defined anti-PTEN monoclonal antibodies (mAbs), characterized with precision in terms of sensitivity for the detection technique, specificity for PTEN binding, and constraints of epitope recognition. This is especially relevant taking into consideration that PTEN is highly targeted by mutations and posttranslational modifications, and different PTEN protein isoforms exist. The precise characterization of anti-PTEN mAb reactivity is an important step in the validation of these reagents as diagnostic and prognostic tools in clinical oncology, including their routine use in analytical immunohistochemistry (IHC). Here, we review the current status on the use of well-defined anti-PTEN mAbs for PTEN immunodetection in the clinical context and discuss their potential usefulness and limitations for a more precise cancer diagnosis and patient benefit.

PTEN in Colorectal Cancer: Shedding Light on Its Role as Predictor and Target

Molecular assessment of colorectal cancer (CRC) is receiving growing attention, beyond RAS and BRAF, because of its influence on prognosis and prediction in cancer treatment. PTEN (phosphatase and tensin homologue), a tumor suppressor, regulating cell division and apoptosis, has been explored, and significant evidence suggests a role in cetuximab and panitumumab resistance linked to the epidermal growth factor receptor (EGFR) signal transduction pathway. Factors influencing PTEN activity should be analyzed to develop strategies to maximize the tumor suppressor role and to improve tumor response to cancer treatment. Therefore, an in-depth knowledge of the PI3K-Akt pathway—one of the major cancer survival pathways—and the role of PTEN—a major brake of this pathway—is essential in the era of precision medicine. The purpose of this literature review is to summarize the role of PTEN as a predictive factor and possible therapeutic target in CRC, focusing on ongoing studies and the possible implications in clinical practice.

PTEN Alterations as a Potential Mechanism for Tumor Cell Escape from PD-1/PD-L1 Inhibition

The recent approval of immune checkpoint inhibitors drastically changed the standard treatments in many advanced cancer patients, but molecular changes within the tumor can prevent the activity of immunotherapy drugs. Thus, the introduction of the inhibitors of the immune checkpoint programmed death-1/programmed death ligand-1 (PD-1/PD-L1), should prompt deeper studies on resistance mechanisms, which can be caused by oncogenic mutations detected in cancer cells. PTEN, a tumor suppressor gene, dephosphorylates the lipid signaling intermediate PIP₃ with inhibition of AKT activity, one of the main effectors of the PI3K signaling axis. As a consequence of genetic or epigenetic aberrations, PTEN expression is often altered, with increased activation of PI3K axis. Interestingly, some data confirmed that loss of PTEN expression modified the pattern of cytokine secretion creating an immune-suppressive microenvironment with increase of immune cell populations that can promote tumor progression. Moreover, PTEN loss may be ascribed to reduction of tumor infiltrating lymphocytes (TILs), which can explain the absence of activity of immune checkpoint inhibitors. This review describes the role of PTEN loss as a mechanism responsible for resistance to anti PD-1/PD-L1 treatment. Moreover, combinatorial strategies between PD-1/PD-L1 inhibitors and PI3K/AKT targeting drugs are proposed as a new strategy to overcome resistance to immune checkpoint inhibition.

LINC01198 promotes proliferation and temozolomide resistance in a NEDD4-1-dependent manner, repressing PTEN expression in glioma

Background: Dysregulation of numerous lncRNAs has been recently confirmed in glioma; however, the majority of their roles and mechanisms involved in this notorious disease remain largely unclear. This study aims to explore the roles and molecular mechanisms of LINC01198 implicated in the proliferation and chemoresistance in glioma.

Results: LINC01198 was elevated in glioma, and this predicted a poorer prognosis for patients with glioma. LINC01198 knockdown inhibited, while LINC01198 overexpression promoted, glioma cell proliferation and resistance to temozolomide. Mechanistically, NEDD4-1 (neural precursor cell expressed, developmentally downregulated 4, E3 ubiquitin protein ligase) and phosphatase and tensin homolog (PTEN) were recruited by LINC01198, which functioned as a scaffold. Moreover, we showed that LINC01198 exerted its oncogenic activities by enhancing the NEDD4-1-dependent repression of PTEN.

Conclusions: Our study elucidated the role of oncogenic LINC01198 in glioma proliferation and temozolomide resistance, and this role may serve as a promising target for glioma therapy.

Methods: LINC01198 expression in glioma tissues and that in paired normal tissues were measured by qRT-PCR. The functional roles of LINC01198 in glioma were demonstrated by a series of in vitro experiments. CCK-8 assay, RNA pulldown, RNA immunoprecipitation and western blotting were used to demonstrate the potential mechanisms of LINC01198.

PTEN in Lung Cancer: Dealing with the Problem, Building on New Knowledge and Turning the Game Around

Lung cancer is the most common malignancy and cause of cancer deaths worldwide, owing to the dismal prognosis for most affected patients. Phosphatase and tensin homolog deleted in chromosome 10 (PTEN) acts as a powerful tumor suppressor gene and even partial reduction of its levels increases cancer susceptibility. While the most validated anti-oncogenic duty of PTEN is the negative regulation of the PI3K/mTOR/Akt oncogenic signaling pathway, further tumor suppressor functions, such as chromosomal integrity and DNA repair have been reported. PTEN protein loss is a frequent event in lung cancer, but genetic alterations are not equally detected. It has been demonstrated that its expression is regulated at multiple genetic and epigenetic levels and deeper delineation of these mechanisms might provide fertile ground for upgrading lung cancer therapeutics. Today, PTEN expression is usually determined by immunohistochemistry and low protein levels have been associated with decreased survival in lung cancer. Moreover, available data involve PTEN mutations and loss of activity with resistance to targeted treatments and immunotherapy. This review discusses the current knowledge about PTEN status in lung cancer, highlighting the prevalence of its alterations in the disease, the regulatory mechanisms and the implications of PTEN on available treatment options.

PTEN Tumor-Suppressor: The Dam of Stemness in Cancer

PTEN is one of the most frequently inactivated tumor suppressor genes in cancer. Loss or variation in PTEN gene/protein levels is commonly observed in a broad spectrum of human cancers, while germline PTEN mutations cause inherited syndromes that lead to increased risk of tumors. PTEN restrains tumorigenesis through different mechanisms ranging from phosphatase-dependent and independent activities, subcellular localization and protein interaction, modulating a broad array of cellular functions including growth, proliferation, survival, DNA repair, and cell motility. The main target of PTEN phosphatase activity is one of the most significant cell growth and pro-survival signaling pathway in cancer: PI3K/AKT/mTOR. Several shreds of evidence shed light on the critical role of PTEN in normal and cancer stem cells (CSCs) homeostasis, with its loss fostering the CSC compartment in both solid and hematologic malignancies. CSCs are responsible for tumor propagation, metastatic spread, resistance to therapy, and relapse. Thus, understanding how alterations of PTEN levels affect CSC hallmarks could be crucial for the development of successful therapeutic approaches. Here, we discuss the most significant findings on PTEN-mediated control of CSC state. We aim to unravel the role of PTEN in the regulation of key mechanisms specific for CSCs, such as self-renewal, quiescence/cell cycle, Epithelial-to-Mesenchymal-Transition (EMT), with a particular focus on PTEN-based therapy resistance mechanisms and their exploitation for novel therapeutic approaches in cancer treatment.

MicroRNA-4286 promotes cell proliferation, migration, and invasion via PTEN regulation of the PI3K/Akt pathway in non-small cell lung cancer

It is well-known that phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a tumor suppressor which negatively regulates PI3K/AKT signaling and is activated widely in non-small cell lung cancers (NSCLC). However, genetic alterations in PTEN genes are rare, suggesting an undefined mechanism(s) for their suppression. Notably, growing evidence indicates that PTEN can be regulated by microRNAs involved in cancer progression. In this study, we discover that the miR-4286 is overexpressed in NSCLC and negatively regulates the expression of PTEN. Furthermore, we found that miR-4286 reduces PTEN expression by directly binding to PTEN 3'-untranslated region (UTR), thereby inhibiting NSCLC cell proliferation and mobility. Moreover, mechanistic investigations revealed that miR-4286 overexpression was a result of PTEN-mediated activation of the PI3K/AKT pathway. Taken together, our findings elucidate that miR-4286 promotes the tumorigenesis of NSCLC by interacting with PTEN. This miR-4286-mediated upregulation of PTEN might lead to new therapeutic strategies for NSCLC.

PTEN Is Associated With Worse Local Control in Early Stage Supraglottic Laryngeal Cancer Treated With Radiotherapy

Objectives

The aim of this study was to establish the prognostic value of the epidermal growth factor receptor (EGFR) and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression on local control in patients with early stage supraglottic laryngeal squamous cell carcinoma (LSCC) treated with radiotherapy only.

Study design

Retrospective cohort study.

Methods

Immunohistochemical staining for EGFR and PTEN was performed on pretreatment biopsies of a selected well-defined homogeneous group of 52 patients with T1-T2 supraglottic LSCC treated with radiotherapy between 1990 and 2008. Kaplan-Meier analysis and univariate and multivariate Cox Regression analyses were performed to correlate clinical data and expression levels of EGFR and PTEN with local control.

Results

Kaplan-Meier survival analysis and Cox Regression analysis showed a significant association between PTEN expression and local control (hazard ratio [HR] = 3.26, 95% confidence interval [CI] = 1.14-9.33, P = .027) and between lymph node status and local control (HR = 3.60, 95% CI = 1.26-10.31, P = .017). Both were independent prognostic factors in a multivariate analysis (HR = 3.28, 95% CI = 1.14-9.39, P = .027 and HR = 3.62, 95% CI = 1.26-10.37, P = .017, respectively). There was no significant association between EGFR expression and local control (HR = 1.32, 95% CI = 1.17-10.14, P = .79).

Conclusion

This study showed an association between both high PTEN expression and the presence of lymph node metastasis and deteriorated local control in early stage supraglottic LSCC treated with radiotherapy.

Level of Evidence

NA.

Mechanisms of PTEN loss in cancer: It's all about diversity

PTEN is a phosphatase which metabolises PIP₃, the lipid product of PI 3-Kinase, directly opposing the activation of the oncogenic PI3K/AKT/mTOR signalling network. Accordingly, loss of function of the PTEN tumour suppressor is one of the most common events observed in many types of cancer. Although the mechanisms by which PTEN function is disrupted are diverse, the most frequently observed events are deletion of a single gene copy of PTEN and gene silencing, usually observed in tumours with little or no PTEN protein detectable by immunohistochemistry. Accordingly, with the exceptions of glioblastoma and endometrial cancer, mutations of the PTEN coding sequence are uncommon (<10%) in most types of cancer. Here we review the data relating to PTEN loss in seven common tumour types and discuss mechanisms of PTEN regulation, some of which appear to contribute to reduced PTEN protein levels in cancers.

VAOS, a novel vanadyl complexes of alginate saccharides, inducing apoptosis via activation of AKT-dependent ROS production in NSCLC

Previous studies have confirmed that protein tyrosine phosphatase 1B (PTP1B) can promote tumour progression in non-small cell lung cancer (NSCLC). Vanadyl alginate oligosaccharides (VAOS) is a new coordination compounds that possesses a good PTP1B inhibitory activity. However, the potent anticancer efficacy of VAOS in human NSCLC requires further study. In this study, VAOS exhibited effective inhibitory effects in NSCLC both in cultured cells and in a xenograft mouse model. VAOS was further identified to induce NSCLC cell apoptosis through activating protein kinase B (AKT) to elevate intracellular reactive oxygen species (ROS) levels by increasing in oxygen consumption and impairing the ROS-scavenging system. Neither silencing of PTP1B by siRNA nor transient overexpression of PTP1B had an effect on the AKT phosphorylation triggered by VAOS, indicating that PTP1B inhibition was not involved in VAOS-induced apoptosis. Through phosphorus colorimetric assay, we demonstrated that VAOS notably inhibited phosphatase and tensin homologue deleted on chromosome 10 (PTEN) dephosphorylation activity, another member of the protein tyrosine phosphatases (PTPases)-upstream factor of AKT. Interestingly, PTEN knockdown sensitized cells to VAOS, whereas ectopic expression of PTEN markedly rescued VAOS-mediated lethality. In vivo, VAOS treatment markedly reduced PTEN activity and tumour cell burden with low systemic toxicity. Thus, our data not only provided a new therapeutic drug candidate for NSCLC, but presented new understanding into the pharmacological research of VAOS.

Autophagy regulates vinorelbine sensitivity due to continued Keap1-mediated ROS generation in lung adenocarcinoma cells

Autophagy is one of the induced mechanisms in metastatic cancer to escape death due to starvation, hypoxia, metabolic stresses, chemotherapy, and radiation. Some publications have revealed that chemotherapy combined with autophagy inhibitor will overcome drug resistance. We modified AS2 cells with PTEN overexpression, mTOR knockdown, or Keap1 knockdown, and made modification of A549 cells with PTEN knockdown, Atg5 knockdown, and Keap1 overexpression. Our study was aimed toward an exploration of how autophagy modulates Keap1, ROS generation, and vinorelbine-induced apoptosis in these cell lines. We found that lung cancer PC14PE6/AS2 (AS2) had higher mTOR and Akt and also lower PTEN expression than A549 cells. Descended autophagy was demonstrated with more decreased p62 accumulation and LC3 II conversion in AS2 cells as compared to A549 cells. The A549 cells had lower Keap1/Nrf2 and more active anti-oxidant response element (ARE) activity than the AS2 cells. We modified AS2 cells with PTEN overexpression, mTOR knockdown, Keap1 knockdown, and revealed amplified p62 and LC3 expression accompanied with decreased Akt, Keap1, ROS, and vinorelbine-induced apoptosis. Declined p62, LC3 expression were accompanied with increased Akt, Keap1, ROS, and vinorelbine-induced apoptosis after modification of A549 cells with PTEN knockdown, Atg5 knockdown, and Keap1 overexpression. Keap1 overexpression lowered ARE levels in A549 cells, and ARE level exhibited up-growth in Keap1 knockdown AS2 cells. The autophagy inhibitor caused more ROS generation and vinorelbine-induced apoptosis in the A549 and CL1-5 cells. According to these findings, autophagy regulates vinorelbine sensitivity by continuing Keap1-mediated ROS generation in lung adenocarcinoma cells.

It needs more evidence to prove that chemotherapy combined with autophagy inhibitor will overcome drug resistance. The pilot study demonstrated a VNR-sensitive strategy in lung adenocarcinoma cells, by which regulators of autophagy modulated Keap1-mediated ROS generation and VNR-induced apoptosis.