Autophagy promotes escape from phosphatidylinositol 3-kinase inhibition in estrogen receptor-positive breast cancer

MYC upstream region orchestrates resistance to PI3K inhibitors in cancer cells through FOXO3a-mediated autophagic adaptation

The MYC oncogene is frequently overexpressed in tumors and inhibition of its translation is considered an attractive therapeutic opportunity. Despite numerous reports proposing an internal ribosome entry site (IRES) within the MYC Upstream Region (MYC UR) to sustain MYC translation during cellular stress or chemotherapy, conflicting evidence remains regarding the validity of such a mechanism. Through comprehensive investigations in MYC-driven Colorectal Cancer (CRC) and Burkitt Lymphoma (BL) cells, we demonstrate that MYC UR does not facilitate cap-independent translation, but instead orchestrates resistance to PI3K inhibitors. Genomic deletion of MYC UR neither impacts MYC protein levels nor viability in CRC cells, either untreated or exposed to cellular stress. However, in response to PI3K inhibitors, MYC UR drives a FOXO3a-dependent transcriptional upregulation of MYC, conferring drug resistance. This resistance is mediated by enhanced autophagic flux, governed by MYC, and blockade of autophagy sensitizes CRC cells to PI3K inhibition in vitro and in vivo. Remarkably, BL cells lacking the translocation of MYC UR exhibit sensitivity to PI3K inhibitors, whereas MYC UR-translocated cells respond to these drugs only when autophagy is inhibited. These findings challenge previous notions regarding IRES-mediated translation and highlight a promising strategy to overcome resistance to PI3K inhibitors in MYC-driven malignancies, offering potential clinical implications for CRC and BL treatment.

The "Road" to Malignant Transformation from Endometriosis to Endometriosis-Associated Ovarian Cancers (EAOCs): An mTOR-Centred Review

Ovarian cancer is an umbrella term covering a number of distinct subtypes. Endometrioid and clear-cell ovarian carcinoma are endometriosis-associated ovarian cancers (EAOCs) frequently arising from ectopic endometrium in the ovary. The mechanistic target of rapamycin (mTOR) is a crucial regulator of cellular homeostasis and is dysregulated in both endometriosis and endometriosis-associated ovarian cancer, potentially favouring carcinogenesis across a spectrum from benign disease with cancer-like characteristics, through an atypical phase, to frank malignancy. In this review, we focus on mTOR dysregulation in endometriosis and EAOCs, investigating cancer driver gene mutations and their potential interaction with the mTOR pathway. Additionally, we explore the complex pathogenesis of transformation, considering environmental, hormonal, and epigenetic factors. We then discuss postmenopausal endometriosis pathogenesis and propensity for malignant transformation. Finally, we summarize the current advancements in mTOR-targeted therapeutics for endometriosis and EAOCs.

Cirsiliol induces autophagy and mitochondrial apoptosis through the AKT/FOXO1 axis and influences methotrexate resistance in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common primary malignant bone tumor in children and adolescents, with poor outcomes for patients with metastatic disease or chemotherapy resistance. Cirsiliol is a recently found flavonoid with anti-tumor effects in various tumors. However, the effects of cirsiliol in the regulation of aggressive behaviors of OS remain unknown.

METHODS

The effect of cirsiliol on the proliferation of OS cells was detected using a cell counting kit-8 (CCK-8) assay and 5-ethynyl-2'-deoxyuridine (EdU) staining, while cell apoptosis was detected using flow cytometry. Immunofluorescence was applied to visualize the expression level of the mitochondria, lysosomes and microtubule-associated protein light chain 3 (LC3). A computational molecular docking technique was used to predict the interaction between cirsiliol and the AKT protein. The impact of cirsiliol on resistance was investigated by comparing it between a methotrexate (MTX)-sensitive OS cell line, U2OS, and a MTX-resistant OS cell line, U2OS/MTX. Finally, in situ xenogeneic tumor models were used to validate the anti-tumor effect of cirsiliol in OS.

RESULTS

Cirsiliol inhibited cell proliferation and induced apoptosis in both U2OS and U2OS/MTX300 OS cells. In addition, treatment with cirsiliol resulted in G2 phase arrest in U2OS/MTX300 and U2OS cells. Cell fluorescence probe staining results showed impaired mitochondria and increased autophagy in OS cells after treatment with cirsiliol. Mechanistically, it was found that cirsiliol targeted AKT by reducing the phosphorylation of AKT, which further activated the transcriptional activity of forkhead Box O transcription factor 1 (FOXO1), ultimately affecting the function of OS cells. Moreover, in situ tumorigenesis experiments showed that cirsiliol inhibited the tumorigenesis and progression of OS in vivo.

CONCLUSIONS

Cirsiliol inhibits OS cell growth and induces cell apoptosis by reducing AKT phosphorylation and further promotes FOXO1 expression. These phenomena indicate that cirsiliol is a promising treatment option for OS.

The "Self-eating" of cancer-associated fibroblast: A potential target for cancer

Autophagy helps maintain energy homeostasis and protect cells from stress effects by selectively removing misfolded/polyubiquitylated proteins, lipids, and damaged mitochondria. Cancer-associated fibroblasts (CAFs) are cellular components of tumor microenvironment (TME). Autophagy in CAFs inhibits tumor development in the early stages; however, it has a tumor-promoting effect in advanced stages. In this review, we aimed to summarize the modulators responsible for the induction of autophagy in CAFs, such as hypoxia, nutrient deprivation, mitochondrial stress, and endoplasmic reticulum stress. In addition, we aimed to present autophagy-related signaling pathways in CAFs, and role of autophagy in CAF activation, tumor progression, tumor immune microenvironment. Autophagy in CAFs may be an emerging target for tumor therapy. In summary, autophagy in CAFs is regulated by a variety of modulators and can reshape tumor immune microenvironment, affecting tumor progression and treatment.

Autophagy modulation in breast cancer utilizing nanomaterials and nanoparticles

Autophagy regenerates cellular nutrients, recycles metabolites, and maintains hemostasis through multistep signaling pathways, in conjunction with lysosomal degradation mechanisms. In tumor cells, autophagy has been shown to play a dual role as both tumor suppressor and tumor promoter, leading to the discovery of new therapeutic strategies for cancer. Therefore, regulation of autophagy is essential during cancer progression. In this regard, the use of nanoparticles (NPs) is a promising technique in the clinic to modulate autophagy pathways. Here, we summarized the importance of breast cancer worldwide, and we discussed its classification, current treatment strategies, and the strengths and weaknesses of available treatments. We have also described the application of NPs and nanocarriers (NCs) in breast cancer treatment and their capability to modulate autophagy. Then the advantages and disadvantaged of NPs in cancer therapy along with future applications will be disscussed. The purpose of this review is to provide up-to-date information on NPs used in breast cancer treatment and their impacts on autophagy pathways for researchers.

Molecular Mechanisms of Anti-Estrogen Therapy Resistance and Novel Targeted Therapies

Breast cancer (BC) is the most commonly diagnosed cancer in women, constituting one-third of all cancers in women, and it is the second leading cause of cancer-related deaths in the United States. Anti-estrogen therapies, such as selective estrogen receptor modulators, significantly improve survival in estrogen receptor-positive (ER+) BC patients, which represents about 70% of cases. However, about 60% of patients inevitably experience intrinsic or acquired resistance to anti-estrogen therapies, representing a major clinical problem that leads to relapse, metastasis, and patient deaths. The resistance mechanisms involve mutations of the direct targets of anti-estrogen therapies, compensatory survival pathways, as well as alterations in the expression of non-coding RNAs (e.g., microRNA) that regulate the activity of survival and signaling pathways. Although cyclin-dependent kinase 4/6 and phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) inhibitors have significantly improved survival, the efficacy of these therapies alone and in combination with anti-estrogen therapy for advanced ER+ BC, are not curative in advanced and metastatic disease. Therefore, understanding the molecular mechanisms causing treatment resistance is critical for developing highly effective therapies and improving patient survival. This review focuses on the key mechanisms that contribute to anti-estrogen therapy resistance and potential new treatment strategies alone and in combination with anti-estrogen drugs to improve the survival of BC patients.

Unraveling the Roles of Protein Kinases in Autophagy: An Update on Small-Molecule Compounds for Targeted Therapy

Protein kinases, which catalyze the phosphorylation of proteins, are involved in several important cellular processes, such as autophagy. Of note, autophagy, originally described as a mechanism for intracellular waste disposal and recovery, has been becoming a crucial biological process closely related to many types of human diseases. More recently, the roles of protein kinases in autophagy have been gradually elucidated, and the design of small-molecule compounds to modulate targets to positively or negatively interfere with the cytoprotective autophagy or autophagy-associated cell death may provide a new clue on the current targeted therapy. Thus, in this Perspective, we focus on summarizing the different roles of protein kinases, including positive, negative, and bidirectional regulations of autophagy. Moreover, we discuss several small-molecule compounds targeting these protein kinases in human diseases, highlighting their pivotal roles in autophagy for targeted therapeutic purposes.

Effects of PI3K inhibition in AI-resistant breast cancer cell lines: autophagy, apoptosis, and cell cycle progression

INTRODUCTION

Breast cancer is the leading cause of cancer death in women. The aromatase inhibitors (AIs), Anastrozole (Ana), Letrozole (Let), and Exemestane (Exe) are a first-line treatment option for estrogen receptor-positive (ER⁺) breast tumors, in postmenopausal women. Nevertheless, the development of acquired resistance to this therapy is a major drawback. The involvement of PI3K in resistance, through activation of the PI3K/AKT/mTOR survival pathway or through a cytoprotective autophagic process, is widely described.

MATERIALS AND METHODS

The involvement of autophagy in response to Ana and Let treatments and the effects of the combination of BYL-719, a PI3K inhibitor, with AIs were explored in AI-resistant breast cancer cell lines (LTEDaro, AnaR, LetR, and ExeR).

RESULTS

We demonstrate that Ana and Let treatments do not promote autophagy in resistant breast cancer cells, contrary to Exe. Moreover, the combinations of BYL-719 with AIs decrease cell viability by different mechanisms by nonsteroidal vs. steroidal AIs. The combination of BYL-719 with Ana or Let induced cell cycle arrest while the combination with Exe promoted cell cycle arrest and apoptosis. In addition, BYL-719 decreased AnaR, LetR, and ExeR cell viability in a dose- and time-dependent manner, being more effective in the ExeR cell line. This decrease was further exacerbated by ICI 182,780.

CONCLUSION

These results corroborate the lack of cross-resistance between AIs verified in the clinic, excluding autophagy as a mechanism of resistance to Ana or Let and supporting the ongoing clinical trials combining BYL-719 with AIs.

Do Wortmannin and Thalidomide induce apoptosis by autophagy inhibition in 4T1 breast cancer cells in vitro and in vivo?

The aim of this study was to show the effects of autophagy inhibitor Wortmannin and antiangiogenic-proapoptotic Thalidomide on autophagy and apoptosis markers in 4T1 breast cancer cells in vitro and in vivo. The half-maximal inhibitory concentration (IC50) values of 4T1 cells for Wortmannin and Thalidomide were evaluated by Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. After cancer formation in 28 BALB/C female mice, drugs were administered for seven days. Cells and tissue sections were evaluated for anti-phosphoinositide 3-kinase (PI3K), anti- the microtubule-associated protein 1 light chain3 (MAPLC3β), anti-caspase 8, anti-caspase 9, and anti-caspase 3 immunoreactivities by immunohistochemical staining and apoptosis by Terminal Transferase dUTP Nick End Labeling (TUNEL) assay. Both PI3K and MAPLC3β immunoreactivities decreased in all treatments when compared to control group except Thalidomide treatment in primary cancer tissue. The caspase 3, 8, and 9 immunoreactivities were increased in all treatment groups and TUNEL positive cells were the highest in the Wortmannin and Thalidomide group. Our findings suggest that autophagy is an important mechanism for 4T1 cells and both Wortmannin and Thalidomide treatments inhibit autophagy and induce apoptosis. In primary cancer tissues, autophagy was not effective as in vitro. The treatment of Wortmannin and Thalidomide increased the apoptotic cells in vivo independent from autophagy inhibition. Different results may be because of microenvironment. Further studies must be done to elucidate the effect of microenvironment.

The present and future of PI3K inhibitors for cancer therapy

Phosphoinositide-3- kinase (PI3K) signaling regulates cellular proliferation, survival and metabolism, and its aberrant activation is one of the most frequent oncogenic events across human cancers. In the last few decades, research focused on the development of PI3K inhibitors, from preclinical tool compounds to the highly specific medicines approved to treat patients with cancer. Herein we discuss current paradigms for PI3K inhibitors in cancer therapy, focusing on clinical data and mechanisms of action. We also discuss current limitations in the use of PI3K inhibitors including toxicities and mechanisms of resistance, with specific emphasis on approaches aimed to improve their efficacy.

Targeting autophagy enhances atezolizumab-induced mitochondria-related apoptosis in osteosarcoma

In this study, we identified the multifaceted effects of atezolizumab, a specific monoclonal antibody against PD-L1, in tumor suppression except for restoring antitumor immunity, and investigated the promising ways to improve its efficacy. Atezolizumab could inhibit the proliferation and induce immune-independent apoptosis of osteosarcoma cells. With further exploration, we found that atezolizumab could impair mitochondria of osteosarcoma cells, resulting in increased release of reactive oxygen species and cytochrome-c, eventually leading to mitochondrial-related apoptosis via activating JNK pathway. Nevertheless, the excessive release of reactive oxygen species also activated the protective autophagy of osteosarcoma cells. Therefore, when we combined atezolizumab with autophagy inhibitors, the cytotoxic effect of atezolizumab on osteosarcoma cells was significantly enhanced in vitro. Further in vivo experiments also confirmed that atezolizumab combined with chloroquine achieved the most significant antitumor effect. Taken together, our study indicates that atezolizumab can induce mitochondrial-related apoptosis and protective autophagy independently of the immune system, and targeting autophagy is a promising combinatorial approach to amplify its cytotoxicity.

DNA damage response and breast cancer development: Possible therapeutic applications of ATR, ATM, PARP, BRCA1 inhibition

Breast cancer is the most common and significant cancers in females regarding the loss of life quality. Similar to other cancers, one of the etiologic factors in breast cancer is DNA damage. A plethora of molecules are responsible for sensing DNA damage and mediating actions which lead to DNA repair, senescence, cell cycle arrest and if damage is unbearable to apoptosis. In each of these, aberrations leading to unrepaired damage was resulted in uncontrolled proliferation and cancer. Another cellular function is autophagy defined as a process eliminating of unnecessary proteins in stress cases involved in pathogenesis of cancer. Knowing their role in cancer, scholars have tried to develop strategies in order to target DDR and autophagy. Further, the interactions of DDR and autophagy plus their regulatory role on each other have been focused simultaneously. The present review study has aimed to illustrate the importance of DDR and autophagy in breast cancer according to the related studies and uncover the relation between DDR and autophagy and its significance in breast cancer therapy.

Matrine exerts anti‑breast cancer activity by mediating apoptosis and protective autophagy via the AKT/mTOR pathway in MCF‑7 cells

Matrine, a major alkaloid isolated from the traditional Chinese herb Sophora flavescens, has been used clinically to treat breast cancer in China. However, the effects of matrine on apoptosis and autophagy in breast cancer cells remain unclear. In the present study, the anti‑breast cancer capacity of matrine was evaluated and its role in regulating apoptosis and autophagy in vitro was investigated. Matrine significantly inhibited the growth of MCF‑7 cells. In addition, Hoechst 33342 staining and Annexin V/propidium iodide staining demonstrated that incubation with matrine induced apoptosis in MCF‑7 cells. Furthermore, matrine induced autophagy in MCF‑7 cells, manifesting as an accumulation of light chain 3 II and downregulation of p62. Additionally, matrine suppressed AKT and mammalian target of rapamycin (mTOR) phosphorylation, indicating that the AKT/mTOR pathway is involved in matrine‑induced apoptosis and autophagy. Overall, the results of the present study indicated that matrine possesses anti‑breast cancer activity by providing protective autophagy via inhibition of the AKT/mTOR pathway. These findings indicated that matrine may be a promising candidate for drug development targeting breast cancer.

Cancer risk in a large inception SLE cohort: Effects of demographics, smoking, and medications

OBJECTIVE

To assess cancer risk factors in incident SLE.

METHODS

Clinical variables and cancer outcomes were assessed annually among incident SLE patients. Multivariate hazard regression models (over-all risk, and most common cancers) included demographics and time-dependent medications (corticosteroids, antimalarial drugs, immunosuppressants), smoking, and adjusted mean SLE Disease Activity Index-2K.

RESULTS

Among 1668 patients (average 9 years follow-up), 65 cancers occurred: 15 breast, 10 non-melanoma skin, seven lung, six hematological, six prostate, five melanoma, three cervical, three renal, two each gastric, head and neck, and thyroid, and one each rectal, sarcoma, thymoma, and uterine cancers. Half of cancers (including all lung cancers) occurred in past/current smokers, versus one-third of patients without cancer. Multivariate analyses indicated over-all cancer risk was related primarily to male sex and older age at SLE diagnosis. In addition, smoking was associated with lung cancer. For breast cancer risk, age was positively and anti-malarial drugs were negatively associated. Anti-malarial drugs and higher disease activity were also negatively associated with non-melanoma skin cancer (NMSC) risk, whereas age and cyclophosphamide were positively associated. Disease activity was associated positively with hematologic and negatively with NMSC risk.

CONCLUSIONS

Smoking is a key modifiable risk factor, especially for lung cancer, in SLE. Immunosuppressive medications were not clearly associated with higher risk except for cyclophosphamide and NMSC. Antimalarials were negatively associated with breast cancer and NMSC risk. SLE activity was associated positively with hematologic cancer and negatively with NMSC. Since the absolute number of cancers was small, additional follow-up will help consolidate these findings.

Targeting PARP and autophagy evoked synergistic lethality in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), one of the most lethal malignancies worldwide, has limited efficient therapeutic options. Here, we first demonstrated that simultaneously targeting poly (ADP-ribose) polymerase (PARP) and autophagy could evoke striking synergistic lethality in HCC cells. Specifically, we found that the PARP inhibitor Niraparib induced cytotoxicity accompanied by significant autophagy formation and autophagic flux in HCC cells. Further experiments showed that Niraparib induced suppression of the Akt/mTOR pathway and activation of the Erk1/2 cascade, two typical signaling pathways related to autophagy. In addition, the accumulation of reactive oxygen species was triggered, which was involved in Niraparib-induced autophagy. Blocking autophagy by chloroquine (CQ) in combination with Niraparib further enhanced cytotoxicity, induced apoptosis and inhibited colony formation in HCC cells. Synergistic inhibition was also observed in Huh7 xenografts in vivo. Mechanistically, we showed that autophagy inhibition abrogated Niraparib-induced cell-cycle arrest and checkpoint activation. Cotreatment with CQ and Niraparib promoted the formation of γ-H2AX foci while inhibiting the recruitment of the homologous recombination repair protein RAD51 to double-strand break sites. Thus, the present study developed a novel promising strategy for the management of HCC in the clinic and highlighted a potential approach to expand the application of PARP inhibitors.

Actively Targeted Nanodelivery of Echinomycin Induces Autophagy-Mediated Death in Chemoresistant Pancreatic Cancer In Vivo

Pancreatic cancer remains a recalcitrant neoplasm associated with chemoresistance and high fatality. Because it is frequently resistant to apoptosis, exploiting autophagic cell death could offer a new treatment approach. We repurpose echinomycin, an antibiotic encapsulated within a syndecan-1 actively targeted nanoparticle, for treatment of pancreatic cancer. Tumor-specific uptake, biodistribution, efficacy of nanodelivered echinomycin, and mechanism of cell death were assessed in aggressive, metastatic models of pancreatic cancer. In these autophagic-dependent pancreatic cancer models, echinomycin treatment resulted in autophagic cell death noted by high levels of LC3 among other autophagy markers, but without hallmarks of apoptosis, e.g., caspase activation and chromatin fragmentation, or necrosis, e.g., plasma membrane degradation and chromatin condensation/degrading. In vivo, biodistribution of syndecan-1-targeted nanoparticles indicated preferential S2VP10 or S2CP9 tumor uptake compared to the liver and kidney (S2VP10 p = 0.0016, p = 0.00004 and S2CP9 p = 0.0009, p = 0.0001). Actively targeted nanodelivered echinomycin resulted in significant survival increases compared to Gemzar (S2VP10 p = 0.0003, S2CP9 p = 0.0017) or echinomycin only (S2VP10 p = 0.0096, S2CP9 p = 0.0073). We demonstrate that actively targeted nanodelivery of echinomycin results in autophagic cell death in pancreatic and potentially other high-autophagy, apoptosis-resistant tumors. Collectively, these findings support syndecan-1-targeted delivery of echinomycin and dysregulation of autophagy to induce cell death in pancreatic cancer.

Targeting autophagy-related protein kinases for potential therapeutic purpose

Autophagy, defined as a scavenging process of protein aggregates and damaged organelles mediated by lysosomes, plays a significant role in the quality control of macromolecules and organelles. Since protein kinases are integral to the autophagy process, it is critically important to understand the role of kinases in autophagic regulation. At present, intervention of autophagic processes by small-molecule modulators targeting specific kinases has becoming a reasonable and prevalent strategy for treating several varieties of human disease, especially cancer. In this review, we describe the role of some autophagy-related kinase targets and kinase-mediated phosphorylation mechanisms in autophagy regulation. We also summarize the small-molecule kinase inhibitors/activators of these targets, highlighting the opportunities of these new therapeutic agents.

Molecular Mechanisms Underlying Autophagy-Mediated Treatment Resistance in Cancer

Despite advances in diagnostic tools and therapeutic options, treatment resistance remains a challenge for many cancer patients. Recent studies have found evidence that autophagy, a cellular pathway that delivers cytoplasmic components to lysosomes for degradation and recycling, contributes to treatment resistance in different cancer types. A role for autophagy in resistance to chemotherapies and targeted therapies has been described based largely on associations with various signaling pathways, including MAPK and PI3K/AKT signaling. However, our current understanding of the molecular mechanisms underlying the role of autophagy in facilitating treatment resistance remains limited. Here we provide a comprehensive summary of the evidence linking autophagy to major signaling pathways in the context of treatment resistance and tumor progression, and then highlight recently emerged molecular mechanisms underlying autophagy and the p62/KEAP1/NRF2 and FOXO3A/PUMA axes in chemoresistance.

Overexpression of iASPP is required for autophagy in response to oxidative stress in choriocarcinoma

Background

Gestational trophoblastic disease (GTD) is a heterogeneous group of diseases developed from trophoblasts. ASPP (Ankyrin-repeat, SH3-domain and proline-rich region containing protein) family proteins, ASPP1 and ASPP2, have been reported to be dysregulated in GTD. They modulate p53 activities and are responsible for multiple cellular processes. Nevertheless, the functional role of the ASPP family inhibitory member, iASPP, is not well characterized in GTD.

Methods

To study the functional role of iASPP in GTD, trophoblastic tissues from normal placentas, hydatidiform mole (HM) and choriocarcinoma were used for immunohistochemistry, whereas siRNAs were used to manipulate iASPP expression in choriocarcinoma cell lines and study the subsequent molecular changes.

Results

We demonstrated that iASPP was overexpressed in both HM and choriocarcinoma when compared to normal placenta. Progressive increase in iASPP expression from HM to choriocarcinoma suggests that iASPP may be related to the development of trophoblastic malignancy. High iASPP expression in HM was also significantly associated with a high expression of autophagy-related protein LC3. Interestingly, iASPP silencing retarded the growth of choriocarcinoma through senescence instead of induction of apoptosis. LC3 expression decreased once iASPP was knocked down, suggesting a downregulation on autophagy. This may be due to iASPP downregulation rendered decrease in Atg5 expression and concomitantly hindered autophagy in choriocarcinoma cells. Autophagy inhibition per se had no effect on the growth of choriocarcinoma cells but increased the susceptibility of choriocarcinoma cells to oxidative stress, implying a protective role of iASPP against oxidative stress through autophagy in choriocarcinoma.

Conclusions

iASPP regulates growth and the cellular responses towards oxidative stress in choriocarcinoma cells. Its overexpression is advantageous to the pathogenesis of GTD. (266 words).

Toward fully exploiting the therapeutic potential of marketed pharmaceuticals: the use of octreotide and chloroquine in oncology

Pleiotropy in biological systems and their targeting allows many pharmaceuticals to be used for multiple therapeutic purposes. Fully exploiting the therapeutic properties of drugs that are already marketed would be highly advantageous. This is especially the case in the field of oncology, where the ineffectiveness of typical anticancer agents is a common issue, while the development of novel anticancer agents is a costly and particularly time-consuming process. Octreotide and chloroquine are two pharmaceuticals that exhibit profound antitumorigenic activities. However, the current therapeutic use of octreotide is restricted primarily to the management of acromegaly and neuroendocrine tumors, both of which are rare medical conditions. Similarly, chloroquine is used mainly for the treatment of malaria, which is designated as a rare disease in Western countries. This limited exploitation contradicts the experimental findings of numerous studies outlining the possible expansion of the use of octreotide to include the treatment of common human malignancies and the repositioning of chloroquine in oncology. Herein, we review the current knowledge on the antitumor function of these two agents stemming from preclinical or clinical experimentation. In addition, we present in silico evidence on octreotide potentially binding to multiple Wnt-pathway components. This will hopefully aid in the design of new efficacious anticancer therapeutic regimens with minimal toxicity, which represents an enormous unmet demand in oncology.

Hormone-dependent breast cancer: Targeting autophagy and PI3K overcomes Exemestane-acquired resistance

The leading cause of cancer death in women around the world is breast cancer. The aromatase inhibitors (AIs) are considered - as first-line treatment for estrogen receptor-positive (ER⁺) breast tumors, in postmenopausal women. Exemestane (Exe) is a powerful steroidal AI, however, despite its therapeutic success, Exe-acquired resistance may occur leading to tumor relapse. Our group previously demonstrated that autophagy acts as a pro-survival process in Exe-induced cell death of ER⁺ sensitive breast cancer cells. In this work, the role of autophagy and its relationship with the PI3K/AKT/mTOR pathway in Exe-acquired resistance was explored. In that way, the mechanism behind the effects of the combination of Exe with pan-PI3K, or autophagic inhibitors, was studied in a long-term estrogen deprived ER⁺ breast cancer cell line (LTEDaro cells). Our results indicate that Exe induces autophagy as a cytoprotective mechanism linked to acquired resistance. Moreover, it was demonstrated that by inhibiting autophagy and/or PI3K pathway it is possible to revert Exe-resistance through apoptosis promotion, disruption of cell cycle, and inhibition of cell survival pathways. This work provides new insights into the mechanisms involved in Exe-acquired resistance, pointing autophagy as an attractive therapeutic target to surpass it. Thus, it highlights new targets that together with aromatase inhibition may improve ER⁺ breast cancer therapy, overcoming AIs-acquired resistance.

Interplay between elemental imbalance-related PI3K/Akt/mTOR-regulated apoptosis and autophagy in arsenic (III)-induced jejunum toxicity of chicken

Arsenic trioxide (As₂O₃), the most toxic form of arsenic found in foodstuffs, is considered a carcinogen for human and animal. But many of the events that occur during its passage through the gastrointestinal tract are uncharted in birds. This study assesses the toxic effect on the jejunum of chicken which subchronically exposed to diets that contain As₂O₃ (0, 0.625, 1.25, 2.5 mg/kg body weight) for 90 days. Electron microscopy, TdT-mediated dUTP nick-end labeling (TUNEL), qPCR, and Western blot were performed. The results showed that mitochondrial fusion and apoptosis inhibiting genes had degressive trends, whereas mitochondrial fission and apoptosis activating genes presented heightened expressions in the treatment group compared with the control (P < 0.05). Subsequently, significant inhibition in PI3K/AKT/mTOR signaling was observed. Moreover, the expression of autophagy markers (LC3-II/LC3-I, Beclin-1) increased time and dose-dependently. Additionally, metabolic disorders of trace elements were detected evidenced by their significant decreases (aluminum, silicon, calcium, manganese, strontium, titanium, lithium, boron, cobalt, mercury, chromium) and increases (arsenic, cadmium, selenium, lead, nickel) on 90 days using inductively coupled plasma mass spectrometer (ICP-MS). It is possible that the changes of trace elements have a hand in the come on and development of arsenism. Taken together, we conjectured that, in chicken jejunum, arsenic led to redistribution of trace elements, promoting apoptosis via regulating mitochondrial dynamics, leading to autophagy through PI3K/AKT/mTOR signal pathways.