Autophagy Inhibition Contributes to Apoptosis of PLK4 Downregulation-induced Dormant Cells in Colorectal Cancer

NL13, a novel curcumin analogue and polo like kinase 4 inhibitor, induces cell cycle arrest and apoptosis in prostate cancer models

BACKGROUND AND PURPOSE

Prostate cancer remains a major public health burden worldwide. Polo like kinase 4 (PLK4) has emerged as a promising therapeutic target in prostate cancer due to its key roles in cell cycle regulation and tumour progression. This study aims to develop and characterize the novel curcumin analogue NL13 as a potential therapeutic agent and PLK4 inhibitor against prostate cancer.

EXPERIMENTAL APPROACH

NL13 was synthesized and its effects were evaluated in prostate cancer cells and mouse xenograft models. Kinome screening and molecular modelling identified PLK4 as the primary target. Antiproliferative and proapoptotic mechanisms were explored via cell cycle, apoptosis, gene and protein analyses.

KEY RESULTS

Compared with curcumin, NL13 exhibited much greater potency in inhibiting PC3 (IC50, 3.51 μM vs. 35.45 μM) and DU145 (IC50, 2.53 μM vs. 29.35 μM) prostate cancer cells viability and PLK4 kinase activity (2.32 μM vs. 246.88 μM). NL13 induced G2/M cell cycle arrest through CCNB1/CDK1 down-regulation and triggered apoptosis via caspase-9/caspase-3 cleavage. These effects were mediated by PLK4 inhibition, which led to the inactivation of the AKT signalling pathway. In mice, NL13 significantly inhibited tumour growth and modulated molecular markers consistent with in vitro findings, including decreased p-AKT and increased cleaved caspase-9/3.

CONCLUSION AND IMPLICATIONS

NL13, a novel PLK4-targeted curcumin analogue, exerts promising anticancer properties against prostate cancer by disrupting the PLK4-AKT-CCNB1/CDK1 and apoptosis pathways. NL13 represents a promising new agent for prostate cancer therapy.

Colorectal cancer cell dormancy: An insight into pathways

Cancer cell dormancy (CCD) in colorectal cancer (CRC) poses a significant challenge to effective treatment. In CRC, CCD contributes to tumour recurrence, drug resistance, and amplifying the disease's burden. The molecular mechanisms governing CCD and strategies for eliminating dormant cancer cells remain largely unexplored. Therefore, understanding the molecular mechanisms governing dormancy is crucial for improving patient outcomes and developing targeted therapies. This editorial highlights the complex interplay of signalling pathways and factors involved in colorectal CCD, emphasizing the roles of Hippo/YAP, pluripotent transcription factors such as NANOG, HIF-1α signalling, and Notch signalling pathways. Additionally, ERK/p38α/β/MAPK pathways, AKT signalling pathway, and Extracellular Matrix Metalloproteinase Inducer, along with some potential less explored pathways such as STAT/p53 switch and canonical and non-canonical Wnt and SMAD signalling, are also involved in promoting colorectal CCD. Highlighting their clinical significance, these findings may offer the potential for identifying key dormancy regulator pathways, improving treatment strategies, surmounting drug resistance, and advancing personalized medicine approaches. Moreover, insights into dormancy mechanisms could lead to the development of predictive biomarkers for identifying patients at risk of recurrence and the tailoring of targeted therapies based on individual dormancy profiles. It is essential to conduct further research into these pathways and their modulation to fully comprehend CRC dormancy mechanisms and enhance patient outcomes.

Autophagy regulates apoptosis of colorectal cancer cells based on signaling pathways

Colorectal cancer is a common malignant tumor of the digestive system. Its morbidity and mortality rank among the highest in the world. Cancer development is associated with aberrant signaling pathways. Autophagy is a process of cell self-digestion that maintains the intracellular environment and has a bidirectional regulatory role in cancer. Apoptosis is one of the important death programs in cancer cells and is able to inhibit cancer development. Studies have shown that a variety of substances can regulate autophagy and apoptosis in colorectal cancer cells through signaling pathways, and participate in the regulation of autophagy on apoptosis. In this paper, we focus on the relevant research on autophagy in colorectal cancer cells based on the involvement of related signaling pathways in the regulation of apoptosis in order to provide new research ideas and therapeutic directions for the treatment of colorectal cancer.

Collagen XVII promotes dormancy of colorectal cancer cells by activating mTORC2 signaling

Tumor dormancy is the underpinning for cancer relapse and chemoresistance, leading to massive cancer-related death in colorectal cancer (CRC). However, our comprehension of the mechanisms dictating tumor dormancy and strategies for eliminating dormant tumor cells remains restricted. In this study, we identified that collagen XVII (COL17A1), a hemidesmosomal transmembrane protein, can promote the dormancy of CRC cells. The upregulation of COL17A1 was observed to prolong quiescence periods and diminish drug susceptibility of CRC cells. Mechanistically, COL17A1 acts as a scaffold, enhancing the crosstalk between mTORC2 and Akt, thereby instigating the mTORC2-mediated dormant signaling. Notably, the activation of mTORC2 is contingent upon the intracellular domain of COL17A1, regardless of its ectodomain shedding. Our findings underscore a pivotal role of the COL17A1-mTORC2 axis in CRC dormancy, suggesting that mTORC2-specific inhibitors may hold therapeutic prospects for the eradication of dormant tumor cells.

Epigenetic regulation of autophagy by non-coding RNAs and exosomal non-coding RNAs in colorectal cancer: A narrative review

One of the major diseases affecting people globally is colorectal cancer (CRC), which is primarily caused by a lack of effective medical treatment and a limited understanding of its underlying mechanisms. Cellular autophagy functions to break down and eliminate superfluous proteins and substances, thereby facilitating the continual replacement of cellular elements and generating vital energy for cell processes. Non-coding RNAs and exosomal ncRNAs have a crucial impact on regulating gene expression and essential cellular functions such as autophagy, metastasis, and treatment resistance. The latest research has indicated that specific ncRNAs and exosomal ncRNA to influence the process of autophagy in CRC cells, which could have significant consequences for the advancement and treatment of this disease. It has been determined that a variety of ncRNAs have a vital function in regulating the genes essential for the formation and maturation of autophagosomes. Furthermore, it has been confirmed that ncRNAs have a considerable influence on the signaling pathways associated with autophagy, such as those involving AMPK, AKT, and mTOR. Additionally, numerous ncRNAs have the potential to affect specific genes involved in autophagy. This study delves into the control mechanisms of ncRNAs and exosomal ncRNAs and examines how they simultaneously influence autophagy in CRC.

Unveiling the role of cellular dormancy in cancer progression and recurrence

PURPOSE OF REVIEW

Cellular dormancy is a major contributor to cancer progression and recurrence. This review explores recent findings on the molecular mechanisms implicated in cancer dormancy and investigates potential strategies to improve therapeutic interventions.

RECENT FINDINGS

Research on cancer dormancy reveals a complex and multifaceted phenomenon. Providing a latent reservoir of tumor cells with reduced proliferation and enhanced drug-tolerance, dormant cancer cells emerge from a clonally diverse population after therapy or at metastatic sites. These cells exhibit distinct transcriptional and epigenetic profiles, involving the downregulation of Myc and mechanistic target of rapamycin (mTOR) pathways, and the induction of autophagy. Senescence traits, under the control of factors such as p53, also contribute significantly. The tumor microenvironment can either promote or prevent dormancy establishment, notably through the involvement of T and NK cells within the dormant tumor niche. Strategies to combat dormancy-related relapse include direct elimination of dormant tumor cells, sustaining dormancy to prolong survival, or awakening dormant cells to re-sensitize them to antiproliferative drugs.

SUMMARY

Improving our understanding of cancer dormancy at primary and secondary sites provides valuable insights into patient care and relapse prevention.

Dormant cancer cells and polyploid giant cancer cells: The roots of cancer recurrence and metastasis

Tumour cell dormancy is critical for metastasis and resistance to chemoradiotherapy. Polyploid giant cancer cells (PGCCs) with giant or multiple nuclei and high DNA content have the properties of cancer stem cell and single PGCCs can individually generate tumours in immunodeficient mice. PGCCs represent a dormant form of cancer cells that survive harsh tumour conditions and contribute to tumour recurrence. Hypoxic mimics, chemotherapeutics, radiation and cytotoxic traditional Chinese medicines can induce PGCCs formation through endoreduplication and/or cell fusion. After incubation, dormant PGCCs can recover from the treatment and produce daughter cells with strong proliferative, migratory and invasive abilities via asymmetric cell division. Additionally, PGCCs can resist hypoxia or chemical stress and have a distinct protein signature that involves chromatin remodelling and cell cycle regulation. Dormant PGCCs form the cellular basis for therapeutic resistance, metastatic cascade and disease recurrence. This review summarises regulatory mechanisms governing dormant cancer cells entry and exit of dormancy, which may be used by PGCCs, and potential therapeutic strategies for targeting PGCCs.