Inhibiting Src-mediated PARP1 tyrosine phosphorylation confers synthetic lethality to PARP1 inhibition in HCC

HBXIP induces PARP1 via WTAP-mediated m6A modification and CEBPA-activated transcription in cisplatin resistance to hepatoma

Poly (ADP-ribose) polymerase 1 (PARP1) is a DNA-binding protein that is involved in various biological functions, including DNA damage repair and transcription regulation. It plays a crucial role in cisplatin resistance. Nevertheless, the exact regulatory pathways governing PARP1 have not yet been fully elucidated. In this study, we present evidence suggesting that the hepatitis B X-interacting protein (HBXIP) may exert regulatory control over PARP1. HBXIP functions as a transcriptional coactivator and is positively associated with PARP1 expression in tissues obtained from hepatoma patients in clinical settings, and its high expression promotes cisplatin resistance in hepatoma. We discovered that the oncogene HBXIP increases the level of PARP1 m6A modification by upregulating the RNA methyltransferase WTAP, leading to the accumulation of the PARP1 protein. In this process, on the one hand, HBXIP jointly activates the transcription factor ETV5, promoting the activation of the WTAP promoter and further facilitating the promotion of the m6A modification of PARP1 by WTAP methyltransferase, enhancing the RNA stability of PARP1. On the other hand, HBXIP can also jointly activate the transcription factor CEBPA, enhance the activity of the PARP1 promoter, and promote the upregulation of PARP1 expression, ultimately leading to enhanced DNA damage repair capability and promoting cisplatin resistance in hepatoma. Notably, aspirin inhibits HBXIP, thereby reducing the expression of PARP1. Overall, our research revealed a novel mechanism for increasing PARP1 abundance, and aspirin therapy could overcome cisplatin resistance in hepatoma.

SKP2 promotes the metastasis of pancreatic ductal adenocarcinoma by suppressing TRIM21-mediated PSPC1 degradation

Despite significant advances in diagnostic techniques and treatment approaches, the prognosis of pancreatic ductal adenocarcinoma (PDAC) is still poor. Previous studies have reported that S-phase kinase-associated protein 2 (SKP2), a subunit of the SCF E3 ubiquitin ligase complex, is engaged in the malignant biological behavior of some tumor entities. However, SKP2 has not been fully investigated in PDAC. In the present study, it was observed that high expression of SKP2 significantly correlates with decreased survival time. Further experiments suggested that SKP2 promotes metastasis by interacting with the putative transcription factor paraspeckle component 1 (PSPC1). According to the results of coimmunoprecipitation and ubiquitination assays, SKP2 depletion resulted in the polyubiquitination of PSPC1, followed by its degradation. Furthermore, the SKP2-mediated ubiquitination of PSPC1 partially depended on the activity of the E3 ligase TRIM21. In addition, inhibition of the SKP2/PSPC1 axis by SMIP004, a traditional inhibitor of SKP2, impaired the migration of PDAC cells. In summary, this study provides novel insight into the mechanisms involved in PDAC malignant progression. Targeting the SKP2/PSPC1 axis is a promising strategy for the treatment of PDAC.

Polo-like kinase 4 promotes tumorigenesis and glucose metabolism in glioma by activating AKT1 signaling

Glioblastoma (GBM) is an extremely aggressive tumor associated with a poor prognosis that impacts the central nervous system. Increasing evidence suggests an inherent association between glucose metabolism dysregulation and the aggression of GBM. Polo-like kinase 4 (PLK4), a highly conserved serine/threonine protein kinase, was found to relate to glioma progression and unfavorable prognosis. As revealed by the integration of proteomics and phosphoproteomics, PLK4 was found to be involved in governing metabolic processes and the PI3K/AKT/mTOR pathway. For the first time, this study supports evidence demonstrating that PLK4 activated PI3K/AKT/mTOR signaling through direct binding to AKT1 and subsequent phosphorylating AKT1 at S124, T308, and S473 to promote tumorigenesis and glucose metabolism in glioma. In addition, PLK4-mediated phosphorylation of AKT1 S124 significantly augmented the phosphorylation of AKT1 S473. Therefore, PLK4 exerted an influence on glucose metabolism by stimulating PI3K/AKT/mTOR signaling. Additionally, the expression of PLK4 protein exhibited a positive correlation with AKT1 phosphorylation in glioma patient tissues. These findings highlight the pivotal role of PLK4-mediated phosphorylation of AKT1 in glioma tumorigenesis and dysregulation of glucose metabolism.

Phenethyl isothiocyanate and dasatinib combination synergistically reduces hepatocellular carcinoma growth via cell cycle arrest and oxeiptosis

Introduction: Hepatocellular carcinoma (HCC) is the most common type of liver cancer, which is among the most lethal tumours. Combination therapy exploits multiple drugs to target key pathways synergistically to reduce tumour growth. Isothiocyanates have been shown to possess anticancer potential and to complement the anticancer activity of other compounds. This study aimed to investigate the potential of phenethyl isothiocyanate (PEITC) to synergise with dasatinib, improving its anticancer potential in HCC. Methods: MTT, 3D spheroids and clonogenic assays were used to assess the combination anti-tumour effect in vitro, whereas a murine syngeneic model was employed to evaluate the combination efficacy in vivo. DCFDA staining was employed to evaluate the production of reactive oxygen species (ROS), while flow cytometry and Western blot assays were used to elucidate the molecular mechanism of the synergistic activiy. Results: PEITC and dasatinib combination exhibited a synergistic effect in vitro and in vivo. The combination induced DNA damage and oxidative stress through the production of ROS, which led to the formation of a premature CDK1/Cyclin B1 complex associated with induction of mitotic catastrophe. Furthermore, ROS activated oxeiptosis, a caspase-independent form of programmed cell death. Conclusion: PEITC showed to enhance dasatinib action in treating HCC with increased production of ROS that induced cell cycle arrest followed by mitotic catastrophe, and to induce oxeiptosis. These results highlight the role that ITCs may have in cancer therapy as a complement of clinically approved chemotherapeutic drugs.

Regulated cell death (RCD) in cancer: key pathways and targeted therapies

Regulated cell death (RCD), also well-known as programmed cell death (PCD), refers to the form of cell death that can be regulated by a variety of biomacromolecules, which is distinctive from accidental cell death (ACD). Accumulating evidence has revealed that RCD subroutines are the key features of tumorigenesis, which may ultimately lead to the establishment of different potential therapeutic strategies. Hitherto, targeting the subroutines of RCD with pharmacological small-molecule compounds has been emerging as a promising therapeutic avenue, which has rapidly progressed in many types of human cancers. Thus, in this review, we focus on summarizing not only the key apoptotic and autophagy-dependent cell death signaling pathways, but the crucial pathways of other RCD subroutines, including necroptosis, pyroptosis, ferroptosis, parthanatos, entosis, NETosis and lysosome-dependent cell death (LCD) in cancer. Moreover, we further discuss the current situation of several small-molecule compounds targeting the different RCD subroutines to improve cancer treatment, such as single-target, dual or multiple-target small-molecule compounds, drug combinations, and some new emerging therapeutic strategies that would together shed new light on future directions to attack cancer cell vulnerabilities with small-molecule drugs targeting RCD for therapeutic purposes.

Targeting Src-Hic-5 Signal Cascade for Preventing Migration of Cholangiocarcinoma Cell HuCCT1

Cholangiocarcinoma (CCA) is the second most common primary liver cancer with poor prognosis. The deregulation of a lot of oncogenic signaling molecules, such as receptor tyrosine kinases (RTKs), has been found to be associated with CCA progression. However, RTKs-based target therapy showed limited improvement suggesting a need to search for alternative targets for preventing CCA progression. To address this issue, we screened the oncogenic signal molecules upregulated in surgical tissues of CCAs. Interestingly, over-expression of hydrogen peroxide inducible clone-5 (Hic-5) coupled with over-activation of Src, AKT, JNK were observed in 50% of the cholangiocarcinoma with metastatic potential. To investigate whether these molecules may work together to trigger metastatic signaling, their up-and-down relationship was examined in a well-established cholangiocarcinoma cell line, HuCCT1. Src inhibitors PP1 (IC50, 13.4 μM) and dasatinib (IC50, 0.1 μM) significantly decreased both phosphorylated AKT (phosphor-AKT Thr450) and Hic-5 in HuCCT1. In addition, a knockdown of Hic-5 effectively suppressed activation of Src, JNK, and AKT. These implicated a positive cross-talk occurred between Hic-5 and Src for triggering AKT activation. Further, depletion of Hic-5 and inhibition of Src suppressed HuccT1 cell migration in a dose-dependent manner. Remarkably, prior transfection of Hic-5 siRNA for 24 h followed by treatment with PP1 or dasatinib for 24 h resulted in additive suppression of HuCCT1 migration. This suggested that a promising combinatory efficacy can be achieved by depletion of Hic-5 coupled with inhibition of Src. In the future, target therapy against CCA progression by co-targeting Hic-5 and Src may be successfully developed in vivo.