Beclin1 inhibition enhances paclitaxel‑mediated cytotoxicity in breast cancer in vitro and in vivo

Metadherin inhibits chemosensitivity of triple-negative breast cancer to paclitaxel via activation of AKT/GSK-3β signaling pathway

Triple-negative breast cancer (TNBC) has an aggressive clinical course, and paclitaxel (PTX)-based chemotherapy remains the main therapeutic drug. Metadherin (MTDH) acts as an oncogene that regulates proliferation, invasion, metastasis, and chemoresistance. This study aimed to investigate whether TNBC chemosensitivity to PTX was related to the MTDH/AKT/glycogen synthase kinase-3beta (GSK-3β) pathway. Clinical baseline characteristics and immunohistochemistry (IHC) were used to evaluate the expression and prognosis of MTDH and AKT (protein kinase B, PKB) in TNBC patient samples. MTDH shRNA, MTDH overexpression vector, MK-2206, and PTX intervention were used in cell models and mouse tumor-bearing models. Afterwards, mRNA and protein levels were assessed using quantitative real-time polymerase chain reaction and Western blot. Evaluate the level of tumor cell apoptosis and cell cycle using flow cytometry. Cell viability was detected using Cell Count Kit 8. The in vivo imaging system is used to analyze the growth of tumors. We found that higher expression of MTDH or AKT resulted in poorer disease-free survival and a lower Miller-Payne grade. MTDH promotes cell proliferation and increases p-AKT and p-GSK-3β expression in TNBC cells. Notably, suppression of AKT terminated MTDH overexpression-induced cell proliferation and apoptosis. MTDH knockdown or the AKT inhibitor MK2206 reduced the p-AKT and p-GSK-3β ratio, reduced cell viability and proliferation, increased cell apoptosis, and increased chemosensitivity to PTX. In vivo, xenograft tumors of an MTDH knockdown+MK2206 group treated with PTX were the smallest compared to other groups. In short, MTDH inhibits TNBC chemosensitivity to PTX by activating the AKT/GSK-3β signaling pathway.

SMAC Mimetic BV6 Co-Treatment Downregulates the Factors Involved in Resistance and Relapse of Cancer: IAPs and Autophagy

Cancer is the utmost common disease-causing death worldwide, characterized by uncontrollable cell division with the potential of metastasis. Overexpression of the Inhibitors of Apoptosis proteins (IAPs) and autophagy correlates with tumorigenesis, therapeutic resistance, and reoccurrence after anticancer therapies. This study illuminates the role and efficacy of smac mimetic compound BV6 alone and in co-treatment with death ligands such as TRAIL and TNFα in the regulation of cell death mechanisms, i.e., apoptosis and autophagy. In this study, MTT assays, wound healing assays, and cellular and nuclear morphological studies were done. DAPI staining, AO/EtBr staining and AnnexinV/PI FACS was done to study the apoptosis. The expression of IAPs and autophagy biomarkers was analyzed using Real time-PCR and western blotting. Meanwhile, TEM demonstrated autophagy and cellular autophagic vacuoles in response to the BV6. The result shows a promising anti-cancer effect of BV6 alone as well as in combinational treatment with TRAIL and TNFα, compared to the lone treatment of TRAIL and TNFα in both breast cancer cell lines. The smac mimetic compound might provide an alternative combinational therapy with conventional anticancer therapies to tackle their inefficiency at the advanced stage of cancer, cancer resistance, and reoccurrence. Also, IAPs and autophagic proteins could act as potent target molecules for the development of novel anti-cancer drugs in pathogenesis and the betterment of regimens for cancer.

The role of hypoxia-inducible factor-1 alpha in multidrug-resistant breast cancer

Breast cancer is the most common cancer in women worldwide with increasing incidence. Significant therapeutics advances in the field of breast cancer have resulted in a growing number of treatment options, whereas de novo or acquired resistance is still a persistent clinical challenge. Drug resistance involves a variety of mechanisms, and hypoxia is one of the many causes. Hypoxia-inducible Factor-1 Alpha (HIF-1α) is a key transcription factor which can regulate the response of cells to hypoxia. HIF-1α can trigger anaerobic glycolysis of tumor cells, induce angiogenesis, promote the proliferation, invasion, and migration of tumor cells, and lead to multidrug resistance. This review mainly discusses the role of HIF-1α in the drug-resistant breast cancer and highlighted the potential of HIF-1α -targeted therapy.

Hsa_circ_0020850 promotes the malignant behaviors of lung adenocarcinoma by regulating miR-326/BECN1 axis

Background

Circular RNAs (circRNAs) are a novel type of endogenous RNAs and play vital roles in lung adenocarcinoma. However, the function and underlying mechanism of circ_0020850 in lung adenocarcinoma remain unknown.

Methods

The levels of circ_0020850, microRNA-326 (miR-326), and Beclin1 (BECN1) were analyzed by real-time quantitative polymerase chain reaction and western blot analyses. The migration and invasion were determined by wound healing and transwell assays, respectively. Colony formation assay was used to assess cell proliferation ability. The angiogenic ability was analyzed by Matrigel angiogenesis assay. The apoptosis rate was calculated by flow cytometry assay. Dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays were conducted to confirm the interaction relationship among circ_0020850, miR-326, and BECN1. A xenograft mice model was established to assess the role of circ_0020850 in vivo.

Results

We found that circ_0020850 was obviously overexpressed in lung adenocarcinoma tissues and cells. Knockdown of circ_0020850 inhibited migration, invasion, proliferation, and angiogenesis but induced apoptosis in lung adenocarcinoma cells in vitro, as well as curbed tumor growth in vivo. MiR-326 was a target of circ_0020850, and knockdown of miR-326 abolished the suppression effect of circ_0020850 on the malignant behaviors of lung adenocarcinoma cells. Additionally, miR-326 could negatively regulate BECN1 expression, thereby regulating lung adenocarcinoma cell phenotypes. Importantly, circ_0020850 could directly bind to miR-326 and thus relieve miR-326-mediated inhibition on BECN1.

Conclusion

Circ_0020850 promoted the malignant development of lung adenocarcinoma by regulating miR-326/BECN1 axis, indicating that circ_0020850 might serve as a promising target for the diagnosis and treatment of lung adenocarcinoma patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02480-3.

The Multifaceted Functions of Autophagy in Breast Cancer Development and Treatment

Macroautophagy (herein referred to as autophagy) is a complex catabolic process characterized by the formation of double-membrane vesicles called autophagosomes. During this process, autophagosomes engulf and deliver their intracellular content to lysosomes, where they are degraded by hydrolytic enzymes. Thereby, autophagy provides energy and building blocks to maintain cellular homeostasis and represents a dynamic recycling mechanism. Importantly, the clearance of damaged organelles and aggregated molecules by autophagy in normal cells contributes to cancer prevention. Therefore, the dysfunction of autophagy has a major impact on the cell fate and can contribute to tumorigenesis. Breast cancer is the most common cancer in women and has the highest mortality rate among all cancers in women worldwide. Breast cancer patients often have a good short-term prognosis, but long-term survivors often experience aggressive recurrence. This phenomenon might be explained by the high heterogeneity of breast cancer tumors rendering mammary tumors difficult to target. This review focuses on the mechanisms of autophagy during breast carcinogenesis and sheds light on the role of autophagy in the traits of aggressive breast cancer cells such as migration, invasion, and therapeutic resistance.

Targeting Cytoprotective Autophagy to Enhance Anticancer Therapies

Autophagy is a highly regulated multi-step process that occurs at the basal level in almost all cells. Although the deregulation of the autophagy process has been described in several pathologies, the role of autophagy in cancer as a cytoprotective mechanism is currently well established and supported by experimental and clinical evidence. Our understanding of the molecular mechanism of the autophagy process has largely contributed to defining how we can harness this process to improve the benefit of cancer therapies. While the role of autophagy in tumor resistance to chemotherapy is extensively documented, emerging data point toward autophagy as a mechanism of cancer resistance to radiotherapy, targeted therapy, and immunotherapy. Therefore, manipulating autophagy has emerged as a promising strategy to overcome tumor resistance to various anti-cancer therapies, and autophagy modulators are currently evaluated in combination therapies in several clinical trials. In this review, we will summarize our current knowledge of the impact of genetically and pharmacologically modulating autophagy genes and proteins, involved in the different steps of the autophagy process, on the therapeutic benefit of various cancer therapies. We will also briefly discuss the challenges and limitations to developing potent and selective autophagy inhibitors that could be used in ongoing clinical trials.