Targeting PP2A-dependent autophagy enhances sensitivity to ruxolitinib in JAK2V617F myeloproliferative neoplasms

Metabolic stress induces a double-positive feedback loop between AMPK and SQSTM1/p62 conferring dual activation of AMPK and NFE2L2/NRF2 to synergize antioxidant defense

Co-occurring mutations in KEAP1 in STK11/LKB1-mutant NSCLC activate NFE2L2/NRF2 to compensate for the loss of STK11-AMPK activity during metabolic adaptation. Characterizing the regulatory crosstalk between the STK11-AMPK and KEAP1-NFE2L2 pathways during metabolic stress is crucial for understanding the implications of co-occurring mutations. Here, we found that metabolic stress increased the expression and phosphorylation of SQSTM1/p62, which is essential for the activation of NFE2L2 and AMPK, synergizing antioxidant defense and tumor growth. The SQSTM1-driven dual activation of NFE2L2 and AMPK was achieved by inducing macroautophagic/autophagic degradation of KEAP1 and facilitating the AXIN-STK11-AMPK complex formation on the lysosomal membrane, respectively. In contrast, the STK11-AMPK activity was also required for metabolic stress-induced expression and phosphorylation of SQSTM1, suggesting a double-positive feedback loop between AMPK and SQSTM1. Mechanistically, SQSTM1 expression was increased by the PPP2/PP2A-dependent dephosphorylation of TFEB and TFE3, which was induced by the lysosomal deacidification caused by low glucose metabolism and AMPK-dependent proton reduction. Furthermore, SQSTM1 phosphorylation was increased by MAP3K7/TAK1, which was activated by ROS and pH-dependent secretion of lysosomal Ca2+. Importantly, phosphorylation of SQSTM1 at S24 and S226 was critical for the activation of AMPK and NFE2L2. Notably, the effects caused by metabolic stress were abrogated by the protons provided by lactic acid. Collectively, our data reveal a novel double-positive feedback loop between AMPK and SQSTM1 leading to the dual activation of AMPK and NFE2L2, potentially explaining why co-occurring mutations in STK11 and KEAP1 happen and providing promising therapeutic strategies for lung cancer.Abbreviations: AMPK: AMP-activated protein kinase; BAF1: bafilomycin A1; ConA: concanamycin A; DOX: doxycycline; IP: immunoprecipitation; KEAP1: kelch like ECH associated protein 1; LN: low nutrient; MAP3K7/TAK1: mitogen-activated protein kinase kinase kinase 7; MCOLN1/TRPML1: mucolipin TRP cation channel 1; MEFs: mouse embryonic fibroblasts; MTORC1: mechanistic target of rapamycin kinase complex 1; NAC: N-acetylcysteine; NFE2L2/NRF2: NFE2 like bZIP transcription factor 2; NSCLC: non-small cell lung cancer; PRKAA/AMPKα: protein kinase AMP-activated catalytic subunit alpha; PPP2/PP2A: protein phosphatase 2; ROS: reactive oxygen species; PPP3/calcineurin: protein phosphatase 3; RPS6KB1/p70S6K: ribosomal protein S6 kinase B1; SQSTM1/p62: sequestosome 1; STK11/LKB1: serine/threonine kinase 11; TCL: total cell lysate; TFEB: transcription factor EB; TFE3: transcription factor binding to IGHM enhancer 3; V-ATPase: vacuolar-type H+-translocating ATPase.

Pharmacology Progresses and Applications of Chloroquine in Cancer Therapy

Chloroquine is a common antimalarial drug and is listed in the World Health Organization Standard List of Essential Medicines because of its safety, low cost and ease of use. Besides its antimalarial property, chloroquine also was used in anti-inflammatory and antivirus, especially in antitumor therapy. A mount of data showed that chloroquine mainly relied on autophagy inhibition to exert its antitumor effects. However, recently, more and more researches have revealed that chloroquine acts through other mechanisms that are autophagy-independent. Nevertheless, the current reviews lacked a comprehensive summary of the antitumor mechanism and combined pharmacotherapy of chloroquine. So here we focused on the antitumor properties of chloroquine, summarized the pharmacological mechanisms of antitumor progression of chloroquine dependent or independent of autophagy inhibition. Moreover, we also discussed the side effects and possible application developments of chloroquine. This review provided a more systematic and cutting-edge knowledge involved in the anti-tumor mechanisms and combined pharmacotherapy of chloroquine in hope of carrying out more in-depth exploration of chloroquine and obtaining more clinical applications.

Emerging role of MYB transcription factors in cancer drug resistance

Decades ago, the viral myeloblastosis oncogene v-myb was identified as a gene responsible for the development of avian leukemia. However, the relevance of MYB proteins for human cancer diseases, in particular for solid tumors, remained basically unrecognized for a very long time. The human family of MYB transcription factors comprises MYB (c-MYB), MYBL2 (b-MYB), and MYBL1 (a-MYB), which are overexpressed in several cancers and are associated with cancer progression and resistance to anticancer drugs. In addition to overexpression, the presence of activated MYB-fusion proteins as tumor drivers was described in certain cancers. The identification of anticancer drug resistance mediated by MYB proteins and their underlying mechanisms are of great importance in understanding failures of current therapies and establishing new and more efficient therapy regimens. In addition, new drug candidates targeting MYB transcription factor activity and signaling have emerged as a promising class of potential anticancer therapeutics that could tackle MYB-dependent drug-resistant cancers in a more selective way. This review describes the correlation of MYB transcription factors with the formation and persistence of cancer resistance to various approved and investigational anticancer drugs.

Therapeutic effects and molecular mechanisms of quercetin in gynecological disorders

Quercetin is a representative flavonoid that is widely present in fruits, herbs, and vegetables. It is also an important active core component in traditional Chinese medicines. As an important flavonoid, quercetin has various properties and exerts antioxidant, anti-inflammatory, and cardioprotective effects. The public interest in quercetin is increasing, and quercetin has been used to prevent or treat numerous of diseases, such as polycystic ovary syndrome (PCOS), cancer, autoimmune diseases and chronic cardiovascular diseases, in clinical experiments and animal studies due to its powerful antioxidant properties and minimal side effects. Quercetin exerts marked pharmacological effects on gynecological disorders; however, there have been no reviews about the potential health benefits of quercetin in the context of gynecological disorders, including PCOS, premature ovary failure (POF), endometriosis (EM), ovarian cancer (OC), cervical cancer (CC) and endometrial carcinoma (EC). Thus, this review aimed to summarize the biological effects of quercetin on gynecological disorders and its mechanisms.

Unveiling autophagy complexity in leukemia: The molecular landscape and possible interactions with apoptosis and ferroptosis

Autophagy is a self-digestion multistep process in which causes the homeostasis through degradation of macromolecules and damaged organelles. The autophagy-mediated tumor progression regulation has been a critical point in recent years, revealing the function of this process in reduction or acceleration of carcinogenesis. Leukemia is a haematological malignancy in which abnormal expansion of hematopoietic cells occurs. The current and conventional therapies from chemotherapy to cell transplantation have failed to appropriately treat the leukemia patients. Among the mechanisms dysregulated in leukemia, autophagy is a prominent one in which can regulate the hallmarks of this tumor. The protective autophagy inhibits apoptosis and ferroptosis in leukemia, while toxic autophagy accelerates cell death. The proliferation and invasion of tumor cells are tightly regulated by the autophagy. The direction of regulation depends on the function of autophagy that is protective or lethal. The protective autophagy accelerates chemoresistance and radio-resistsance. The non-coding RNAs, histone transferases and other pathways such as PI3K/Akt/mTOR are among the regulators of autophagy in leukemia progression. The pharmacological intervention for the inhibition or induction of autophagy by the compounds including sesamine, tanshinone IIA and other synthetic compounds can chance progression of leukemia.

Altering phosphorylation in cancer through PP2A modifiers

Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase integral to the regulation of many cellular processes. Due to the deregulation of PP2A in cancer, many of these processes are turned toward promoting tumor progression. Considerable research has been undertaken to discover molecules capable of modulating PP2A activity in cancer. Because PP2A is capable of immense substrate specificity across many cellular processes, the therapeutic targeting of PP2A in cancer can be completed through either enzyme inhibitors or activators. PP2A modulators likewise tend to be effective in drug-resistant cancers and work synergistically with other known cancer therapeutics. In this review, we will discuss the patterns of PP2A deregulation in cancer, and its known downstream signaling pathways important for cancer regulation, along with many activators and inhibitors of PP2A known to inhibit cancer progression.