A Review of mTOR Pathway Inhibitors in Gynecologic Cancer

Signaling pathways in cancer metabolism: mechanisms and therapeutic targets

A wide spectrum of metabolites (mainly, the three major nutrients and their derivatives) can be sensed by specific sensors, then trigger a series of signal transduction pathways and affect the expression levels of genes in epigenetics, which is called metabolite sensing. Life body regulates metabolism, immunity, and inflammation by metabolite sensing, coordinating the pathophysiology of the host to achieve balance with the external environment. Metabolic reprogramming in cancers cause different phenotypic characteristics of cancer cell from normal cell, including cell proliferation, migration, invasion, angiogenesis, etc. Metabolic disorders in cancer cells further create a microenvironment including many kinds of oncometabolites that are conducive to the growth of cancer, thus forming a vicious circle. At the same time, exogenous metabolites can also affect the biological behavior of tumors. Here, we discuss the metabolite sensing mechanisms of the three major nutrients and their derivatives, as well as their abnormalities in the development of various cancers, and discuss the potential therapeutic targets based on metabolite-sensing signaling pathways to prevent the progression of cancer.

Clinical analysis and literature review of a case of ovarian clear cell carcinoma with PIK3CA gene mutation: A case report

RATIONALE

Ovarian clear cell carcinoma (OCCC) is an uncommon malignant form of 5 subtypes of ovarian cancer, accounting for approximately 5% to 25% of all ovarian cancers. OCCC is usually diagnosed at a young age and an early stage. More than 50% of patients are associated with endometriosis. It shows less sensitivity to platinum-based chemotherapies, high recurrence, and poor prognosis, especially late. However, platinum-based chemotherapies remain the first-line treatment. Meanwhile, new treatment modalities have been explored, including immune checkpoint inhibitors and PI3K-AKT-mTOR pathway inhibitors.

PATIENT CONCERN

A 48-year-old Chinese woman, Gravida2 Para1, complained of irregular and painful vaginal bleeding for 4 months.

DIAGNOSIS

The patient was diagnosed with stage IC ovarian clear cell carcinoma that presented with a mutation of the phosphatidylinositol 4,5-bisphosphate 3-kinase alpha subunit (PIK3CA) gene.

INTERVENTION

We performed an early diagnosis and complete surgical resection of the tumor with platinum-based chemotherapy.

OUTCOME

This patient with mutation of the PIK3CA gene was sensitive to platinum-based chemotherapy, showed a significant downwards trend in tumor markers, and was in good health within the year of follow-up.

LESSONS

This study described an OCCC case that presented with a PIK3CA mutation and was successfully managed with careful and complete resection of the tumor. This patient with mutation of the PIK3CA gene was sensitive to platinum-based chemotherapy, showed a significant downwards trend in tumor markers, and did not have recurrence after a year of follow-up, indicating a reasonably good prognosis. Therefore, surgery plus platinum drug chemotherapy is still the best strategy for OCCC treatment. In addition, it is recommended for such patients to undergo genetic testing as much as possible to predict the clinical treatment effect.

CircCASC15-miR-100-mTOR may influence the cervical cancer radioresistance

Background

Cervical cancer has ranked the top one in gynecological malignancies for incidence. Radioresistance is now becoming a leading reason of recurrence.

Methods

Our microRNA array data indicated that the miRNA-100 level decreased significantly during radioresistance. In this study, we up-regulated miR-100 in Hela and Siha cells by using miR-100 mimics and observed proliferation and invasion.

Results

It turned out that with overexpression of miR-100, the cells had less invasiveness as well as proliferation. It may target gene mTOR, and it deed reduced EMT. To examine the role of miR-100 in radioresistance, there was no significant result showed by BSP. While the circCASC15 has been identified with sponge function according to RNA pull down and ISH.

Conclusion

The conclusions indicate miR-100 is a tumor suppressor gene and could be a therapeutic target in radio-resistant cervical cancers.

Dual mTORC1/2 inhibitor AZD2014 diminishes myeloid-derived suppressor cells accumulation in ovarian cancer and delays tumor growth

Mechanistic target of rapamycin (mTOR) forms two distinct complexes, mTOR complex 1 (mTORC1) and mTORC2. Here we investigated the antitumor effect of dual mTORC1/2 inhibitor AZD2014 on epithelial ovarian cancer (EOC) and its potential effect on immunosuppressive myeloid-derived suppressor cells (MDSCs). Immunohistochemical analysis of mTORC1 and mTORC2 was performed on a human ovarian cancer tissue microarray. High mTORC2 expression level was associated with shorter survival in EOC, whereas mTORC1 was not correlate with patients' prognosis. AZD2014 suppressed mTOR signaling pathway in ovarian cancer cells, inhibited proliferation and induced G1-phase cell cycle arrest and apoptosis. In tumor-bearing mice, AZD2014 treatment limited tumor growth, reduced peritoneal ascites, and prolonged survival. AZD2014 specifically reduced MDSCs migration and accumulation in EOC peritoneal fluid but not in the spleen. Moreover, subsequent AZD2014 treatment after cisplatin chemotherapy delayed EOC recurrence. Collectively, we observed that high mTORC2 expression level in EOC indicated a poor prognosis. Remarkably, in tumor-bearing mice, AZD2014 diminished MDSC accumulation and delayed tumor growth and recurrence.

Effective Disease Control After Combinatorial Treatment with a PD-1 Antibody and an mTOR Inhibitor for Recurrent Ovarian Clear Cell Carcinomas: A Case Report and Literature Review

Ovarian clear cell carcinoma (OCCC) is a rare type of epithelial ovarian cancer characterized by a chemoresistant phenotype and high-grade tumor. Conventional therapies for OCCC include surgery and chemotherapy. However, these OCCC treatment approaches are characterized by a high risk of relapse and drug resistance resulting in poor prognosis. Therefore, alternative therapeutic approaches are required to achieve better outcomes. In this study, a PIK3CA p.R88Q mutation and PD-L1 expression with a tumor proportion score of 10% was explored in a patient who presented with rapid recurrence after surgery and unsuccessful postoperative chemotherapy. Based on the clinical condition and the patient preference, she was administered a novel combinatorial therapy comprising mTOR inhibitor everolimus, which is a well-known and potent inhibitor of the PI3K/AKT signaling pathway, and the anti-PD-1 antibody toripalimab. Treatment with this combinatorial therapy showed good prognosis, with more than eight months of disease control, and no severe adverse events were observed. The findings of this study provide a novel and effective strategy for OCCC patients. To the best of our knowledge, this is the first study to report a new combination regimen of immunotherapy (everolimus plus toripalimab) for solid tumors. Everolimus is not only an antitumor targeted drug but also an immunosuppressant; it’s combination with immunotherapy is controversial. This is the first report to demonstrate that it has a synergistic effect.

The Molecular Landscape Influencing Prognoses of Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) is one of the major increasing lethal malignancies of the gynecological tract, mostly due to delayed diagnosis and chemoresistance, as well as its very heterogeneous genetic makeup. Application of high-throughput molecular technologies, gene expression microarrays, and powerful preclinical models has provided a deeper understanding of the molecular characteristics of EOC. Therefore, molecular markers have become a potent tool in EOC management, including prediction of aggressiveness, prognosis, and recurrence, and identification of novel therapeutic targets. In addition, biomarkers derived from genomic/epigenomic alterations (e.g., gene mutations, copy number aberrations, and DNA methylation) enable targeted treatment of affected signaling pathways in advanced EOC, thereby improving the effectiveness of traditional treatments. This review outlines the molecular landscape and discusses the impacts of biomarkers on the detection, diagnosis, surveillance, and therapeutic targets of EOC. These findings focus on the necessity to translate these potential biomarkers into clinical practice.

Cross-Interplay between Osmolytes and mTOR in Alzheimer's Disease Pathogenesis

Alzheimer's disease, categorized by the piling of amyloid-β (Aβ), hyperphosphorylated tau, PHFs, NFTs and mTOR hyperactivity, is a neurodegenerative disorder, affecting people across the globe. Osmolytes are known for osmoprotectants and play a pivotal role in protein folding, function and protein stability, thus, preventing proteins aggregation, and counteracting effects of denaturing solutes on proteins. Osmolytes (viz., sorbitol, inositol, and betaine) perform a pivotal function of maintaining homeostasis during hyperosmotic stress. The selective advantage of utilising osmolytes over inorganic ions by cells is in maintaining cell volume without compromising cell function, which is important for organs such as the brain. Osmolytes have been documented not only as neuroprotectors but they also seem to act as neurodegenerators. Betaine, sucrose and trehalose supplementation has been seen to induce autophagy thereby inhibiting the accumulation of Aβ. In contrast, sucrose has also been associated with mTOR hyperactivity, a hallmark of AD pathology. The neuroprotective action of taurine is revealed when taurine supplementation is seen to inhibit neural damage, apoptosis and oxidative damage. Inositol stereoisomers (viz., scyllo-inositol and myo-inositol) have also been seen to inhibit Aβ production and plaque formation in the brain, inhibiting AD pathogenesis. However, TMAO affects the aging process adversely by deregulating the mTOR signalling pathway and then kindling cognitive dysfunction via degradation of chemical synapses and synaptic plasticity. Thus, it can be concluded that osmolytes may act as a probable therapeutic approach for neurodevelopmental disorders. Here, we have reviewed and focussed upon the impact of osmolytes on mTOR signalling pathway and thereby its role in AD pathogenesis.

The Role of the Signaling Pathways Involved in the Effects of Hydrogen Sulfide on Endoplasmic Reticulum Stress

Endoplasmic reticulum (ER) is a kind of organelle with multiple functions including protein synthesis, modification and folding, calcium storage, and lipid synthesis. Under stress conditions, ER homeostasis is disrupted, which is defined as ER stress (ERS). The accumulation of unfolded proteins in the ER triggers a stable signaling network named unfolded protein response (UPR). Hydrogen sulfide is an important signal molecule regulating various physiological and pathological processes. Recent studies have shown that H₂S plays an important role in many diseases by affecting ERS, but its mechanism, especially the signaling pathways, is not fully understood. Therefore, in this review, we summarize the recent studies about the signaling pathways involved in the effects of H₂S on ERS in diseases to provide theoretical reference for the related in-depth researches.

Progress in the management of endometrial cancer (subtypes, immunotherapy, alterations in PIK3CA pathway): data and perspectives

PURPOSE OF REVIEW

Changes in molecular classification together with a deeper knowledge of both immune disregulation and phosphatidylinositol-3 kinase (PI3K) pathway alterations are leading to a new endometrial cancer treatment paradigm. This review will address the cutting-edge data in this field.

RECENT FINDINGS

This article will cover the updated data in endometrial cancer molecular classification and its correlation with the outcomes in randomized clinical trials (e.g., PORTEC-3). Moreover, we will review the latest data regarding checkpoint blockade molecules (CPB) in the recurrent setting and how they are changing the treatment landscape. In addition, the role of the PI3K inhibitors, their activity, and toxicity profile will be described.

SUMMARY

As result of the incorporation of molecular classification in our daily practice, the adjuvant treatment in endometrial cancer is rapidly evolving and leading to a new paradigm. The promising data observed with CPB in the recurrent setting have led to the food and drug administration approval of pembrolizumab as monotherapy and in combination with lenvatinib. Additionally, the current outcomes achieved with PI3K inhibitor agents encourage us to continue our clinical research to identify those patients who may benefit the most.

Fatostatin in Combination with Tamoxifen Induces Synergistic Inhibition in ER-Positive Breast Cancer

Background

Tamoxifen is the cornerstone of adjuvant therapy for hormone receptor-positive breast cancer. Despite its efficacy, limited drug sensitivity and endocrine resistance remain the important clinical challenges. The main objective of this study was to investigate fatostatin, which was found to sensitize breast cancer to the antitumour effect of tamoxifen both in vitro and in vivo.

Methods

Fatostatin-induced ER degradation was detected by immunoprecipitation assay. The antitumour effect of fatostatin and tamoxifen on MCF-7 and T47D cells was assessed by MTT and colony forming assays. Cell cycle arrest was detected by flow cytometric analysis. Apoptosis was detected by annexin V/propidium iodide double staining and TUNEL assay. Autophagy was detected by MDC assay and acridine orange staining. Migration and invasion assays were performed using a Transwell system, and the efficacy of the synergistic use of fatostatin and tamoxifen in vivo was evaluated using an MCF-7 xenograft model in BALB/c nu/nu female mice.

Results

The synergistic use of fatostatin and tamoxifen significantly suppressed cell viability and invasion, induced cell cycle arrest, and regulated apoptosis and autophagy in MCF-7 and T47D cell lines via PI3K-AKT-mTOR signalling. Additionally, the expression levels of Atg7/12/13, beclin and LC3B increased while p-mTOR and P62 expression levels decreased after treatment with fatostatin and tamoxifen. Tumor growth in the xenograft model was suppressed significantly with the synergistic treatment of fatostatin and tamoxifen.

Conclusion

Fatostatin could induce ER degradation by K48-linked polyubiquitination, which was the key mechanism contributing to tamoxifen inhibition of PI3K-AKT-mTOR signalling in breast cancer. Fatostatin may have a promising clinical use for ER-positive breast cancer patients.

Therapeutic effect of metformin in the treatment of endometrial cancer

The present review aims at reviewing the role of metformin in the treatment of endometrial cancer (EC). According to the literature, excessive estrogen levels and insulin resistance are established risk factors of EC. As a traditional insulin sensitizer and newly discovered anticancer agent, metformin directly and indirectly inhibits the development of EC. The direct mechanisms of metformin include inhibition of the LKB1-AMP-activated protein kinase-mTOR, PI3K-Akt and insulin-like growth factor 1-related signaling pathways, which reduces the proliferation and promotes the apoptosis of EC cells. In the indirect mechanism, metformin increases the insulin sensitivity of body tissues and decreases circulating insulin levels. Decreased levels of insulin increase the blood levels of sex hormone binding globulin, which leads to reductions in circulating estrogen and androgens. The aforementioned findings suggest that metformin serves an important role in the treatment of EC. Increased understanding of the mechanism of metformin in EC may provide novel insights into the treatment of this malignancy.

Novel mTOR Inhibitor Enhances the Sensitivity of Hepatocellular Carcinoma Cells to Molecular Targeting Agents

Background

Although molecular-targeted agents are still the first choice for advanced hepatocellular carcinoma (HCC) treatment, the therapeutic efficacy of these agents is not satisfactory. Recently, the mammalian target of rapamycin (mTOR) is considered to be a promising molecular target that can enhance the sensitivity of HCC cells to antitumor therapy. However, the reported mTOR inhibitors have some shortcomings, and novel mTOR inhibitors need to be developed to enhance the antitumor effect of molecularly targeted agents on advanced HCC.

Methods

In this study, five small-molecular compounds that could serve as potential mTOR-specific inhibitors were identified by virtual screening. The activity of tert-butyl (4-(9-(2-(1,3-dioxolan-2-yl)ethyl)-6-morpholino-9H-purin-2-yl)phenyl)carbamate (compound 4) was measured by enzyme test and Western blot, and its antitumor effect on HCC was examined in nude mice subcutaneous tumor model.

Results

The results showed that 4 is the most effective one in inhibiting the activation of mTOR kinase (mTOR IC₅₀ = 17.52±3.67 nmol/L) among the five lead compounds. Further research in this study indicated that treatment with 4 enhanced the sensitivity of HCC cells to the molecular-targeted agents, such as sorafenib, regorafenib, lenvatinib, anlotinib, and apatinib. In addition, this research indicated that mTOR was correlated with the poor prognosis in patients with advanced HCC who received sorafenib.

Conclusion

Our study identified a new type of small-molecular inhibitors of mTOR and confirmed their ability to enhance the antitumor effect of molecular-targeted agents on advanced HCC.

The expression and significance of mTORC1 in diabetic retinopathy

Background

To investigate the expression and significance of mechanistic target of rapamycin complex 1(mTORC1) in diabetic retinopathy (DR), and to find new targets and new methods for the treatment of DR.

Methods

A DR rat model was prepared by general feeding combined with intraperitoneal injection of 10% streptozotocin (60 mg/kg). The rats were randomly divided into a control group (NDM group) and a diabetes group (DM group). Three months later, the degrees of retinopathy was determined using hematoxylin and eosin staining, and the levels of p-S6, VEGF, and PEDF proteins were detected by immunohistochemistry and western blotting. Human retinal capillary endothelial cells (HRCECs) were cultured in high glucose (HG) conditions, then treated with rapamycin or transfected with siTSC1.The protein levels of p-S6 were assessed by western blotting. The 5-ethynyl-2′-deoxyuridine assay was used to detect cell proliferation, and the Transwell assay was used to detect cell migration.

Results

A DM rat model was successfully developed. The expressions of p-S6 and VEGF proteins were significantly increased in the DM group (p < 0.05), and the expression of PEDF protein was significantly decreased compared with the NDM group (p < 0.05). In vitro, the p-S6 protein, as well as cell proliferation and migration, in HG induced HRCECs were increased (p < 0.05) compared with the control (normal glucose) group (p < 0.05). After transfection with siTSC1 to activate mTORC1, the expression of p-S6, as well as cell proliferation and migration, were increased. In contrast, rapamycin decreased p-S6 expression, as well as proliferation and migration, in HG induced HRCECs compared to the control group (p < 0.05).

Conclusion

mTORC1 plays an important role in DR. After activation, mTORC1 induced expression of the p-S6 protein, regulated the expressions of VEGF and PEDF proteins, and changed the proliferation and migration of endothelial cells. The mTORC1 can therefore be used as a new target,as well as in the treatment of DR.

Elevated MYO10 Predicts Poor Prognosis and its Deletion Hampers Proliferation and Migration Potentials of Cells Through Rewiring PI3K/Akt Signaling in Cervical Cancer

MYO10, recognized as an important regulator of cytoskeleton remodeling, has been reported to be associated with tumorigenesis. However, its functional implication in cervical cancer and potential mechanism still remain to be undetermined currently. MYO10 level in cervical cancer tissues was analyzed by using data retrieved from The Cancer Genome Atlas and ONCOMINE databases. Messenger RNA and protein expression levels were determined by quantitative real-time polymerase chain reaction and Western blotting. Small-interfering RNA and overexpressing plasmid were used for MYO10 silencing and overexpression, and cell proliferation was analyzed by CCK-8. Transwell assays were performed to investigate the ability of cell migration and invasion. MYO10 was upregulated in cervical cancer tissues and cells when compared to normal controls, and survival analysis showed patients with high MYO10 expression had worse overall survival. Moreover, knockdown/overexpression of MYO10 significantly inhibited/enhanced the proliferation, invasion, and migration capabilities of cervical cells transfected with siRNAs/overexpressing plasmid. Additionally, MYO10 silencing inhibited PI3K/Akt signaling pathway by decreasing the phosphorylation status of PI3K and AKT. Data from the present study indicated that MYO10 were overexpressed in patients with cervical cancer and positively linked with poor prognosis. Experimental results suggested that MYO10 induced a significant encouraging effect in cervical cancer cell proliferation, invasion, and migration, linked with involvement of PI3K/Akt signaling. Collectively, these results emphasize a novel role for MYO10 overexpression in cervical cancer and provide a potent therapeutic strategy against cervical cancer.

circRNA MYLK Accelerates Cervical Cancer via Up-Regulation of RHEB and Activation of mTOR Signaling

Background

Growing evidence directly suggested that circular RNAs (circRNAs) are crucial contributors in the course of cervical cancer (CC) onset and progression. Nevertheless, a large number of circRNAs have not been fully addressed in their function and underlying mechanisms during CC etiology.

Purpose

Our study focused on the function of circRNA MYLK (myosin light chain kinase), one novel tumor-related circRNA, in CC cell behaviors.

Methods

Firstly, we evaluated the expression profile of circMYLK in CC cells and in normal Ect1/E6E7 cell line. Moreover, the accurate function of circMYLK in CC cells was assessed via colony formation, CCK-8, EdU, and TUNEL assay. The association among circRNAs, miRNA, and target mRNAs was predicated by bioinformatics methods and validated in mechanical assays.

Results

We disclosed that circMYLK was up-regulated in CC cell lines and acted as a sponge of miR-1301-3p. Besides, downstream miR-1301-3p was capable of reversing circMYLK-mediated CC cell growth and apoptosis. Furthermore, we validated that circMYLK bound to miR-1301-3p as a sponge to upregulate RHEB (Ras homolog, mTORC1 binding) expression. As annotated in prior works, RHEB was responsible for mTOR signaling transduction. Therefore, we investigated whether circMYLK functioned its tumor-facilitating impact in CC through a RHEB-dependent mTOR signaling activation.

Conclusion

It was unveiled that circMYLK sponged miR-1301-3p to promote RHEB expression, which resulted in mTOR signaling activation and CC cell malignant growth.

Virtual Screening and Optimization of Novel mTOR Inhibitors for Radiosensitization of Hepatocellular Carcinoma

Background

Radiotherapy has an ameliorative effect on a wide variety of tumors, but hepatocellular carcinoma (HCC) is insensitive to this treatment. Overactivated mammalian target of rapamycin (mTOR) plays an important part in the resistance of HCC to radiotherapy; thus, mTOR inhibitors have potential as novel radiosensitizers to enhance the efficacy of radiotherapy for HCC.

Methods

A lead compound was found based on pharmacophore modeling and molecular docking, and optimized according to the differences between the ATP-binding pockets of mTOR and PI3K. The radiosensitizing effect of the optimized compound (2a) was confirmed by colony formation assays and DNA double-strand break assays in vitro. The discovery and preclinical characteristics of this compound are described.

Results

The key amino acid residues in mTOR were identified, and a precise virtual screening model was constructed. Compound 2a, with a 4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine scaffold, exhibited promising potency against mTOR (mTOR IC₅₀=7.1 nmol/L (nM)) with 126-fold selectivity over PI3Kα. Moreover, 2a significantly enhanced the sensitivity of HCC to radiotherapy in vitro in a dose-dependent manner.

Conclusion

A new class of selective mTOR inhibitors was developed and their radiosensitization effects were confirmed. This study also provides a basis for developing mTOR-specific inhibitors for use as radiosensitizers for HCC radiotherapy.

Pathogenesis and Clinical Management of Uterine Serous Carcinoma

Uterine serous carcinoma (USC) is an aggressive variant of endometrial cancer that has not been well characterized. It accounts for less than 10% of all endometrial cancers and 80% of endometrial cancer–related deaths. Currently, staging surgery together with chemotherapy or radiotherapy, especially vaginal cuff brachytherapy, is the main treatment strategy for USC. Whole-exome sequencing combined with preclinical and clinical studies are verifying a series of effective and clinically accessible inhibitors targeting frequently altered genes, such as HER2 and PI3K3CA, in varying USC patient populations. Some progress has also been made in the immunotherapy field. The PD-1/PD-L1 pathway has been found to be activated in many USC patients, and clinical trials of PD-1 inhibitors in USC are underway. This review updates the progress of research regarding the molecular pathogenesis and putative clinical management of USC.

The Communication Between the PI3K/AKT/mTOR Pathway and Y-box Binding Protein-1 in Gynecological Cancer

Studies of the mechanistic (mammalian) target of rapamycin inhibitors (mTOR) represent a step towards the targeted treatment of gynecological cancers. It has been shown that women with increased levels of mTOR signaling pathway targets have worse prognosis compared to women with normal mTOR levels. Yet, targeting mTOR alone has led to unsatisfactory outcomes in gynecological cancer. The aim of our review was therefore to provide an overview of the most recent clinical results and basic findings on the interplay of mTOR signaling and cold shock proteins in gynecological malignancies. Due to their oncogenic activity, there are promising data showing that mTOR and Y-box-protein 1 (YB-1) dual targeting improves the inhibition of carcinogenic activity. Although several components differentially expressed in patients with ovarian, endometrial, and cervical cancer of the mTOR were identified, there are only a few investigated downstream actors in gynecological cancer connecting them with YB-1. Our analysis shows that YB-1 is an important player impacting AKT as well as the downstream actors interacting with mTOR such as epidermal growth factor receptor (EGFR), Snail or E-cadherin.

Evaluation of the dual mTOR/PI3K inhibitors Gedatolisib (PF-05212384) and PF-04691502 against ovarian cancer xenograft models

This study investigated the antitumour effects of two dual mTOR/PI3K inhibitors, gedatolisib (WYE-129587/PKI-587/PF-05212384) and PF-04691502 against a panel of six human patient derived ovarian cancer xenograft models. Both dual mTOR/PI3K inhibitors demonstrated antitumour activity against all xenografts tested. The compounds produced tumour stasis during the treatment period and upon cessation of treatment, tumours re-grew. In several models, there was an initial rapid reduction of tumour volume over the first week of treatment before tumour stasis. No toxicity was observed during treatment. Biomarker studies were conducted in two xenograft models; phospho-S6 (Ser235/236) expression (as a readout of mTOR activity) was reduced over the treatment period in the responding xenograft but expression increased to control (no treatment) levels on cessation of treatment. Phospho-AKT (Ser473) expression (as a readout of PI3K) was inhibited by both drugs but less markedly so than phospho-S6 expression. Initial tumour volume reduction on treatment and regrowth rate after treatment cessation was associated with phospho-S6/total S6 expression ratio. Both drugs produced apoptosis but minimally influenced markers of proliferation (Ki67, phospho-histone H3). These results indicate that mTOR/PI3K inhibition can produce broad spectrum tumour growth stasis in ovarian cancer xenograft models during continuous chronic treatment and this is associated with apoptosis.

Drug eruptions associated with tumor therapy: Great imitators

Many studies have investigated cutaneous reactions to antitumor drugs and found them to be quite numerous. We describe drug eruptions that may be associated with different therapies by class: antimetabolite chemotherapeutics, genotoxic agents, spindle inhibitors, signal transduction inhibitors, and immunotherapies. Methotrexate is most often associated with mucocutaneous reactions, alkylating antimetabolite agents with hyperpigmentation, and platinum antimetabolite agents with type I IgE-mediated hypersensitivity reactions. Anthracycline derivatives can induce the hand-foot syndrome in patients, and bleomycin is associated with a bleomycin-induced flagellate erythema. Taxane spindle inhibitors can result in acneiform eruptions, which may also be seen with use of epidermal growth factor receptor inhibitors. Imatinib and its derivatives can cause a truncal maculopapular eruption, whereas multikinase inhibitors can produce a hand-foot-skin reaction. Vemurafenib can result in squamous cell carcinomas and photosensitivity. First-generation mammalian target of rapamycin inhibitors may cause a maculopapular eruption initially involving the face and neck. Programmed death (PD)-1-ligand and receptor inhibitors are associated with bullous pemphigoid. Ipilimumab, targeting Cytotoxic -T- Lymphocyte- associated (CTLA-4) receptors, can cause a morbilliform reaction, whereas Interleukin -2 (IL-2) analogs can create the capillary leak syndrome. Chemotherapeutic drug eruptions classically can manifest in the aforementioned ways; however, it is important to understand that they are associated with myriad cutaneous adverse effects, which may be mistaken for organic skin disease. Oncologists prescribing these medications should be familiar with the cutaneous side effects of these medications, and so they may counsel patients to be on the lookout for them.

Kinase Inhibitors and Ovarian Cancer

Ovarian cancer is fifth in the rankings of cancer deaths among women, and accounts for more deaths than any other gynecological malignancy. Despite some improvement in overall-(OS) and progression-free survival (PFS) following surgery and first-line chemotherapy, there is a need for development of novel and more effective therapeutic strategies. In this mini review, we provide a summary of the current landscape of the clinical use of tyrosine kinase inhibitors (TKIs) and mechanistic target of rapamycin (mTOR) inhibitors in ovarian cancer. Emerging data from phase I and II trials reveals that a combinatorial treatment that includes TKIs and chemotherapy agents seems promising in terms of PFS despite some adverse effects recorded; whereas the use of mTOR inhibitors seems less effective. There is a need for further research into the inhibition of multiple signaling pathways in ovarian cancer and progression to phase III trials for drugs that seem most promising.

Multi-omics profiling reveals distinct microenvironment characterization of endometrial cancer

Endometrial cancer is a heterogeneous disease with distinct molecular characteristics, however, the current clinical trials in immunotherapies have reported only a 13% response rate in endometrial cancer. In this study, we aim to estimate the relative abundance of immune cells infiltrating into the tumor tissues. The samples were clustered based on the immune cell abundance. Most of cluster-specifically mutated genes were detected in clusters I and II, while the copy number alterations were specifically detected in cluster III. Overrepresentation enrichment analysis (ORA) of the genes specifically upregulated in a specific cluster revealed that the immune-related pathways were enriched by the genes in cluster I. Moreover, immune checkpoint proteins and immune co-stimulators were also observed to be highly expressed in cluster I. In addition, we also built a multivariable Cox regression model based on the immune checkpoint genes and co-stimulators. The high-risk and low-risk groups stratified by the risk scores of the Cox model exhibited significant prognostic difference in both training and validation datasets. In summary, the systematic analysis greatly improves our understanding of the immunophenotype of endometrial cancer and its association with biomarkers and prognosis.

Metformin Enhances Nomegestrol Acetate Suppressing Growth of Endometrial Cancer Cells and May Correlate to Downregulating mTOR Activity In Vitro and In Vivo

This study investigated the effect of a novel progestin and its combination with metformin on the growth of endometrial cancer (EC) cells. Inhibitory effects of four progestins, including nomegestrol acetate (NOMAC), medroxyprogesterone acetate, levonorgestrel, and cyproterone acetate, were evaluated in RL95-2, HEC-1A, and KLE cells using cell counting kit-8 assay. Flow cytometry was performed to detect cell cycle and apoptosis. The activity of Akt (protein kinase B), mTOR (mammalian target of rapamycin) and its downstream substrates 4EBP1 (4E-binding protein 1) and eIF4G (Eukaryotic translation initiation factor 4G) were assayed by Western blotting. Nude mice were used to assess antitumor effects in vivo. NOMAC inhibited the growth of RL95-2 and HEC-1A cells, accompanied by arresting the cell cycle at G0/G1 phase, inducing apoptosis, and markedly down-regulating the level of phosphorylated mTOR/4EBP1/eIF4G in both cell lines (p < 0.05). Metformin significantly increased the inhibitory effect of and apoptosis induced by NOMAC and strengthened the depressive effect of NOMAC on activity of mTOR and its downstream substrates, compared to their treatment alone (p < 0.05). In xenograft tumor tissues, metformin (100 mg/kg) enhanced the suppressive effect of NOMAC (100 mg/kg) on mTOR signaling and increased the average concentration of NOMAC by nearly 1.6 times compared to NOMAC treatment alone. Taken together, NOMAC suppressing the growth of EC cells likely correlates to down-regulating the activity of the mTOR pathway and metformin could strengthen this effect. Our findings open a new window for the selection of progestins in hormone therapy of EC.

PI3K-AKT-mTOR and NFκB Pathways in Ovarian Cancer: Implications for Targeted Therapeutics

Ovarian cancer is the most lethal gynecologic malignancy in the United States, with an estimated 22,530 new cases and 13,980 deaths in 2019. Recent studies have indicated that the phosphoinositol 3 kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR), as well as the nuclear factor-κ light chain enhancer of activated B cells (NFκB) pathways are highly mutated and/or hyper-activated in a majority of ovarian cancer patients, and are associated with advanced grade and stage disease and poor prognosis. In this review, we will investigate PI3K/AKT/mTOR and their interconnection with NFκB pathway in ovarian cancer cells.

Dietary Fat and Sugar in Promoting Cancer Development and Progression

The uncontrolled cellular growth that characterizes tumor formation requires a constant delivery of nutrients. Since the 1970s, researchers have wondered if the supply of nutrients from the diet could impact tumor development. Numerous studies have assessed the impact of dietary components, specifically sugar and fat, to increased cancer risk. For the most part, data from these trials have been inconclusive; however, this does not indicate that dietary factors do not contribute to cancer progression. Rather, the dietary contribution may be dependent on tumor, patient, and context, making it difficult to detect in the setting of large trials. In this review, we combine data from prospective cohort trials with mechanistic studies in mice to argue that fat and sugar can play a role in tumorigenesis and disease progression. We find that certain tumors may respond directly to dietary sugar (colorectal and endometrial cancers) and fat (prostate cancer) or indirectly to the obese state (breast cancer).

Endometriosis-associated ovarian cancer: What have we learned so far?

Endometriosis is defined as the presence of ectopic endometrial tissue outside of the uterine cavity, most commonly in the ovaries and peritoneum. It is a complex disease that is influenced by multiple factors. It is also a common gynecological disorder and affects approximately 10-15% of all women of reproductive age. Recent molecular and pathological studies indicate that endometriosis may serve as a precursor of ovarian cancer (endometriosis-associated ovarian cancer, EAOC), particularly endometrioid and clear cell ovarian cancers. Although histological and epidemiological studies have demonstrated that endometriosis has a malignant potential, the molecular mechanism that underlies the malignant transformation of endometriosis is still controversial, and the precise mechanism of carcinogenesis must be fully elucidated. Currently, the development and improvement of a new sequencing technology, next-generation sequencing (NGS), has been increasingly relevant in cancer genomics research. Recently, NGS has also been utilized in clinical oncology to advance the personalized treatment of cancer. In addition, the sensitivity, speed, and cost make NGS a highly attractive platform compared to other sequencing modalities. For this reason, NGS may lead to the identification of driver mutations and underlying pathways associated with EAOC. Here, we present an overview of the molecular pathways that have led to the current opinions on the relationship between endometriosis and ovarian cancer.

mTOR Signaling in Cancer and mTOR Inhibitors in Solid Tumor Targeting Therapy

The mammalian or mechanistic target of rapamycin (mTOR) pathway plays a crucial role in regulation of cell survival, metabolism, growth and protein synthesis in response to upstream signals in both normal physiological and pathological conditions, especially in cancer. Aberrant mTOR signaling resulting from genetic alterations from different levels of the signal cascade is commonly observed in various types of cancers. Upon hyperactivation, mTOR signaling promotes cell proliferation and metabolism that contribute to tumor initiation and progression. In addition, mTOR also negatively regulates autophagy via different ways. We discuss mTOR signaling and its key upstream and downstream factors, the specific genetic changes in the mTOR pathway and the inhibitors of mTOR applied as therapeutic strategies in eight solid tumors. Although monotherapy and combination therapy with mTOR inhibitors have been extensively applied in preclinical and clinical trials in various cancer types, innovative therapies with better efficacy and less drug resistance are still in great need, and new biomarkers and deep sequencing technologies will facilitate these mTOR targeting drugs benefit the cancer patients in personalized therapy.

Gene Expression Analysis Identifies Novel Targets for Cervical Cancer Therapy

Although there has been significant progress in prevention and treatment of cervical cancer, this malignancy is still a leading cause of cancer death for women. Anti-angiogenesis and immunotherapy approaches have been providing survival benefits, however, response rates and durability of response need to be improved. There is a clear need for combination therapies that increase effectiveness of these agents and further improve patient outcome. Previous studies have largely focused on gene expression and molecular pathways in untreated cervix cancer. The goal of this study was to evaluate cancer-specific molecular pathways and their correlation with tumor immune profile in recurrent cervical cancer. Tumor and adjacent normal tissues were used to identify potential combination therapy targets. We found that DNA damage repair pathway genes were significantly overexpressed in the tumor. Based on our results and other recent investigations, we suggest that combination immune checkpoint and PARP inhibitor therapy is a high priority consideration for patients with recurrent, previously treated cervical cancer. We also show that multiple epithelial-mesenchymal transition-related genes, including MAP2K4, ID2, JAK1, FGF2, PIK3R1, AKT3, FGF13, and STAT3 may be potential targets. Interestingly, high-throughput analysis of Cancer Genome Atlas data identified distinct targets, including Fatty acid synthase FASN and Matrix Metallopeptidase 1 MMP1 as novel, promising combination therapy partners.

Chemoresistance and targeting of growth factors/cytokines signalling pathways: towards the development of effective therapeutic strategy for endometrial cancer

Endometrial cancer tends to be an aggressive malignancy. Although the disease prognosis can be good at the early stages of disease, the advanced condition is not curable. Chemotherapy regimens and hormone-based therapy in combination with surgery are major approaches for the management of endometrial cancers. However, intrinsic chemoresistance reduces the success rate and increases the possibility of disease relapse. Investigation of underlying mechanisms revealed altered activation of PI3K/AKT, MAPK, fibroblast growth factor (FGF), mTOR and WNT pathways and reduced gene expression of tumor suppressor p53 in recurrent endometrial cancer. A PTEN mutation, deletion or degradation induces positive p-AKT expression, while PI3K knock-down increases the level of pro-apoptotic proteins and decreases the level of anti-apoptotic ones in cancerous cells. Additionally, RAS proteins trigger both the RAF-MEK-ERK and PI3K-PTEN-AKT signalling mechanisms, thus conferring resistance to anti-tumor agents. FGF up-regulates angiogenesis via receptor-mediated tyrosine kinase activation. Single nucleotide polymorphism, gene amplification or missense mutations of FGFR2 are associated with endometrial cancer. The mTOR complex integrates the nutrient and mitogen signals via AMPKs, S6 kinase 1 (S6K1) and eukaryotic initiation factors, causing unrestricted endometrial cellular proliferation. WNT signalling molecules, such as frizzled receptors, β-catenin, PORCN, RSPO3 and DKK1 undergo dysregulation, and drugs targeting these pathways are under clinical trials in patients with endometrial cancer. Common therapies for endometrial tumor include platinum-based anti-neoplastics, taxanes, nucleoside analogues, immune modulators, FGFR and tyrosine kinase inhibitors, small-molecule mTOR inhibitors and drugs that trigger cell cycle arrest in the G1 phase. Taken together, the current review elucidates the mechanism underlying endometrial cancer, existing therapies and chemoresistance, and points towards the need for novel therapeutics that may promote disease-free survival.

Protective effect of a mechanistic target of rapamycin inhibitor on an in vivo model ofcisplatin-induced ovarian gonadotoxicity

This study aimed to evaluate the protective effect of everolimus, a mechanistic target of rapamycin (mTOR) inhibitor, on cisplatin chemotherapy-induced ovarian toxicity. Eighty sexually mature, virgin, female, 7-week-old C57BL/6J mice were divided into four groups: control, cisplatin (Cis), everolimus (mTORi), and everolimus plus cisplatin (mTORi+Cis). Mice in the Cis and mTORi+Cis groups were intraperitoneally injected with 2 mg/kg of cisplatin for 15 d. Mice in the mTORi and mTORi+Cis groups were orally administered 2.5 mg/kg of everolimus for 29 d, from one week before the first cisplatin injection to one week after the last cisplatin injection. Histological examinations were performed 24 h after the last everolimus administration. The primordial, primary, and antral follicles were significantly depleted in the Cis group compared with that in the control group, confirming the gonadotoxicity of cisplatin. The number of primordial, secondary, and antral follicles was significantly higher in the mTORi+Cis group than in the Cis group, thereby displaying the effect of mTORi-treatment on ovarian protection. Primordial, secondary, and antral follicle counts were similar in the mTORi+Cis and the control groups. The results of this study indicate a protective effect of an mTOR inhibitor against cisplatin chemotherapy-induced gonadotoxicity in the ovarian reserve in an in vivo mouse model.

Hydrogen sulfide and autophagy: A double edged sword

Hydrogen sulfide (H₂S) has been considered the third gaseous signaling molecule that plays important roles in a wide range of physiological and pathological conditions. However, there has been some controversy on the role of H₂S in autophagy. Recent studies indicate that a number of signaling pathways are involved in the pro-autophagy effect of H₂S, such as PI3K/Akt/mTOR, AMPK/mTOR, LKB1/STRAD/MO25, and miR-30c signaling pathways. On the other hand, there are many signaling pathways that play important roles in the anti-autophagy effect of H₂S, including SR-A, PI3K/SGK1/GSK3β, PI3K/AKT/mTOR, Nrf2-ROS-AMPK, AMPK/mTOR, and JNK1 signaling pathways. Novel H₂S-releasing donors/drugs could be designed and identified in order to increase the therapeutic effects by mediating autophagy in human diseases. In this review, the H₂S metabolism in mammals is summarized and the effects of signaling pathways in H₂S-mediated autophagy are further discussed.

Discovery of 1-(3-aryl-4-chlorophenyl)-3-(p-aryl)urea derivatives against breast cancer by inhibiting PI3K/Akt/mTOR and Hedgehog signalings

PI3K/Akt/mTOR and hedgehog (Hh) signalings are two important pathways in breast cancer, which are usually connected with the drug resistance and cancer migration. Many studies indicated that PI3K/Akt/mTOR inhibitors and Hh inhibitors displayed synergistic effects, and the combination of the two signaling drugs could delay drug resistance and inhibit cancer migration in breast cancer. Therefore, the development of molecules simultaneously inhibiting these two pathways is urgent needed. Based on the structures of PI3K inhibitor buparlisib and Hh inhibitor vismodegib, a series of hybrid structures were designed and synthesized utilizing rational drug design and computer-based drug design. Several compounds displayed excellent antiproliferative activities against several breast cancer cell lines, including triple-negative breast cancer (TNBC) MDA-MB-231 cell. Further mechanistic studies demonstrated that the representative compound 9i could inhibit both PI3K/Akt/mTOR and hedgehog (Hh) signalings by inhibiting the phosphorylation of S6K and Akt as well as decreasing the SAG elevated expression of Gli1. Compound 9i could also induce apoptosis remarkably in T47D and MDA-MB-231 cells. In the transwell assay, 9i showed significant inhibition on the migration of MDA-MB-231.

Combining thioridazine and loratadine for the treatment of gastrointestinal tumor

In 2015, the American Society of Clinical Oncology announced that strategies of using combination therapies have been indicated to be effective against many types of cancer. In the present study, thioridazine (THZ) was used in a combination therapy with loratadine (LOR) to target gastrointestinal tumor, with the aim of investigating whether combined therapy was superior to monotherapy in its antitumor effects. The antiproliferative effects on CT26.WT and MFC cells were analyzed using cell-counting kit-8 assay, and synergistic effect was assessed by combination index (Fig. 1). Annexin V and propidium iodide staining indicated the combination therapy was able to induce apoptosis and that this may be mediated via caspase-3, -9 and poly (ADP-ribose) polymerase (PARP) (Fig. 2). Antitumor activity was also evaluated in CT26.WT xenografts in BALB/c mice (Fig. 3). Furthermore, as expected, combination therapy was able to successfully inhibit the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin signaling pathway (Fig. 4). These findings suggest that the combination therapy with THZ and LOR may provide a promising therapy for gastrointestinal cancer.

Platinum-containing compound platinum pyrithione suppresses ovarian tumor proliferation through proteasome inhibition

BACKGROUND

Ovarian carcinoma is one of the most aggressive gynecological malignant neoplasms and makes up 25-30% of all cancer cases of the female genital tract. Currently, resistance to traditional chemotherapy is a great challenge for patients with Epithelial ovarian cancer (EOC). Therefore, identifying novel agents for EOC treatment is essential and urgent.

METHOD

MTS assay was used to analyze the cell viability and proliferation of cancer cells. Flow cytometry was employed to analyze cell cycle distribution and cell apoptosis. Protein signaling pathways were detected by western blot and immunohistochemical staining. Nude mouse experiment was performed to test the in vivo effect of platinum pyrithione (PtPT).

RESULTS

PtPT is a chemically well-characterized synthetic complex of platinum that potently inhibits proteasome-associated deubiquitinases USP14 and UCHL5 activity and shows selective cytotoxicity to multiple cancer cells without damaging DNA. We found that PtPT significantly accumulated ubquitinated-proteins and suppressed the proliferation of multiple EOC cells. Additionally, PtPT induced G2 phase arrest and apoptosis in both A2780 and SKOV3 cells. More importantly, animal experiments showed that PtPT dramatically suppressed the growth of EOC xenografts without obvious side effects.

CONCLUSION

These results suggest that through proteasome inhibition, PtPT significantly suppressed the proliferation of EOC in vitro and in vivo and could be developed as a novel agent for EOC treatment in the future.