Natural compounds targeting YAP/TAZ axis in cancer: Current state of art and challenges

LPA released from dying cancer cells after chemotherapy inactivates Hippo signaling and promotes pancreatic cancer cell repopulation

PURPOSE

The Hippo pathway in the tumorigenesis and progression of PDAC, with lysophosphatidic acid (LPA) regulating the Hippo pathway to facilitate cancer progression. However, the impact of the Hippo signaling pathway on tumor repopulation in PDAC remains unreported.

METHODS

Direct and indirect co-culture models to investigate gemcitabine-induced apoptotic cells can facilitate the repopulation of residual tumor cells. Mass spectrometry analysis was conducted to assess the impact of gemcitabine treatment on the lipid metabolism of pancreatic cancer cells. ELISA assays confirmed gemcitabine promotes the release of LPA from apoptotic pancreatic cancer cells. The expression of Yes-associated protein 1 (YAP1) elucidated the underlying mechanism by which dying cells induce tumor repopulation using qRT-PCR and Western blot. We studied the biological function of pancreatic cancer cells using CCK-8, colony formation, and transwell invasion assays in vitro. Co-culture models were used to validate the impact of Hippo pathway on tumor repopulation, while flow cytometry was employed to assess the sensitivity of pancreatic cancer cells to gemcitabine in the context of Hippo pathway.

RESULTS

Gemcitabine-induced dying cells released LPA in a dose-dependent manner, which promoted the proliferation, clonal formation, and invasion of pancreatic cancer cells. Mechanistic studies showed that gemcitabine and LPA facilitated the translocation of YAP1 and induced the inactivation of the Hippo pathway. YAP1 overexpression significantly enhanced the activity of autotaxin, leading to stimulated pancreatic cancer cells to secrete LPA. This mechanism orchestrated a self-sustaining LPA-Hippo feedback loop, which drove the repopulation of residual tumor cells. Simultaneously, it was observed that suppressing LPA and YAP1 expression enhanced the sensitivity of pancreatic cancer cells to gemcitabine.

CONCLUSION

Our investigation indicated that targeting the LPA-YAP1 signaling pathway could serve as a promising strategy to augment the overall therapeutic efficacy against PDAC.

Gut microbiota and well-being: A comprehensive summary of the special issue

Gut microbes play an immense role in digesting ingested food, providing nutrients to the host, and producing several bioactive metabolites that not only help maintain health but can also elicit disease during dysbiotic conditions. The bioactive compounds derived from gut microbiota metabolites include trimethylamine-N-oxide (TMAO), uremic toxins, short chain fatty acids (SCFAs), phytoestrogens, anthocyanins, bile acids, lipopolysaccharide - to name a few. Once these compounds enter the host cells, tissues, and organs they can cause diseases such as epigenetic, metabolic, neurodegenerative, psychiatric, cardiovascular, hypertension, respiratory, gastrointestinal, kidney, bone, cancer, and others. Regulating healthy gut microbiota thus provides a potential option for the prevention, reversal, or even treatment of these diseases. Towards this end, various interventional strategies are postulated in this field of emerged and rapidly expanding health research arena that includes fecal microbiota transplantation, prebiotics, and probiotics, and to introduce the concept that correcting gut dysbiosis can ameliorate disease symptoms, thus offering a new approach towards dysbiosis-related disease mitigation and treatment. In the special issue of Pharmacological Research titled "Gut Microbiota and Well-Being," several outstanding research findings and review articles are published, covering a broad spectrum of topics related to the influence of gut microbiota on health and disease. This editorial summarizes each of these contributions, prioritizing research findings before discussing the review articles. The summaries are restructured abstracts of relevant articles focusing on major findings or thematic topics.

Leucine-rich repeat-containing 56 promotes breast cancer progression via modulation of the RhoA/ROCKs signaling axis

Breast cancer is one of the most common malignancies with a poor five-year survival rate with metastatic disease among women. It has well been documented that leucine-rich repeat-containing (LRRC) family of proteins are remarkably and aberrantly dysregulated across diverse cancer types. Notably, leucine-rich repeat-containing 56 (LRRC56) was found upregulated in metastatic breast cancer, and plays a crucial role for the movement of cilia via intraflagellar transport 88 (IFT88). However, the role for LRRC56 in breast cancer progression and regulation of IFT88 and associated pathways in metastatic progression of breast cancer has not been defined. Via in vitro functional assessments, we found that LRRC56 pivotally influences the proliferative, migratory and invasive capabilities of cancer cells. Further, via in-vivo assessments, we demonstrated that downregulation of LRRC56 effectively inhibits the growth of breast cancer xenograft tumors and their metastasis to the lungs. Mechanistically, we found that LRRC56 interacts with IFT88 to regulate yes-associated protein 1 (YAP1) expression via modulating the Ras homolog family member A (RhoA)/ Rho-associated protein kinases (ROCKs) signaling pathway. LRRC56 also regulates the expression of integrins and several other key molecules including MMP2, MMP9, FAK, as well as markers of epithelial-mesenchymal transition such as E-cadherin and N-cadherin. In summary, our results demonstrate that overexpression of LRRC56 promotes breast cancer progression via upregulating IFT88/YAP1-RhoA/ROCKs pathway, reprogramming extracellular matrix, and enhancing epithelial-mesenchymal transition. These findings highlight a critical role of LRRC56 in promoting breast cancer progression, suggesting that targeting of LRRC56 may offer a promising strategy for treating metastatic breast cancer.

Celastrol attenuates ferroptosis-mediated intestinal ischemia/reperfusion-induced acute lung injury via Hippo-YAP signaling

BACKGROUND

Acute lung injury commonly arises as a secondary complication following intestinal ischemia/reperfusion (II/R) injury. Celastrol (CEL), recognized for its therapeutic effects on inflammation-related conditions such as acute lung injury. Its protective efficacy against II/R-induced acute lung injury remains insufficiently investigated. The Hippo-YAP signaling pathway regulates ferroptosis and plays a pivotal role in II/R injury.

PURPOSE

To evaluate whether CEL can activate the Hippo-YAP signaling pathway, suppress ferroptosis, and mitigate II/R-induced acute lung injury.

METHODS

Firstly, an II/R model in mice was established, Immunofluorescence staining and Western blot were used to evaluate the effects of CEL on the Hippo signaling pathway and ferroptosis regulation. Network pharmacology predicted the relevance of the Hippo-YAP signaling pathway in CEL's improvement of acute lung injury. Molecular docking experiment indicated that CEL binds effectively to yes-associated protein (YAP), and overexpression of YAP significantly alleviated both lung injury and ferroptosis. Furthermore, the oxygen-glucose deprivation/recovery (OGD/R) model of MLE-12 cells was developed to further confirm CEL's inhibition of ferroptosis via the Hippo-YAP signaling pathway.

RESULTS

CEL ameliorated II/R-induced acute lung injury and inhibited inflammation. In vivo and in vitro studies further revealed that CEL significantly reduced ferroptosis and reactive oxygen species (ROS) accumulation in the lung epithelial cells.

CONCLUSION

CEL effectively mitigated ferroptosis and II/R-induced acute lung injury through elevating YAP protein level, reducing lipid peroxidation, and decreasing intracellular iron accumulation. This study highlights CEL's therapeutic potential for inhibiting ferroptosis, provides mechanistic insights to support CEL's broader therapeutic utility.

Transient activation of YAP/TAZ confers resistance to morusin-induced apoptosis

BACKGROUND

The Hippo signaling pathway involves a kinase cascade that controls phosphorylation of the effector proteins YAP and TAZ, leading to regulation of cell growth, tissue homeostasis, and apoptosis. Morusin, a compound extracted from Morus alba, has shown potential in cancer therapy by targeting multiple signaling pathways, including the PI3K/Akt/mTOR, JAK/STAT, MAPK/ERK, and apoptosis pathways. This study explores the effects of morusin on YAP activation and its implications for apoptosis resistance.

RESULTS

Our investigation revealed that morusin induces transient YAP activation, characterized by the dephosphorylation of YAP at S127 and nuclear localization, followed by gradual rephosphorylation in multiple cancer cells. Notably, this activation occurs independently of the canonical Hippo pathway and involves the LATS1/2, MINK1, and MAPK pathways during the YAP inactivation stage. Furthermore, morusin-induced stress granule formation was significantly impaired in YAP/TAZ-depleted cells, suggesting a role in apoptosis resistance. Additionally, the expression of constitutively active MINK1 maintained YAP activation and reduced apoptosis, indicating that prolonged YAP activation can enhance resistance to cell death.

CONCLUSIONS

These findings suggest that YAP/TAZ are crucial in resistance to morusin-induced apoptosis, and targeting YAP/TAZ could enhance the anti-cancer efficacy of morusin. Our study provides new insights into the molecular mechanisms of morusin, highlighting potential therapeutic strategies against cancer by disrupting apoptosis resistance.

YAP1 Overexpression Enhances the Aerobic Glycolysis Process via Suppression of EGLN2 in Pancreatic Ductal Adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive diseases and has remarkably high mortality rates. In recent years, altered metabolism has been shown to contribute to the maintenance of pancreatic cancer malignancies. However, the molecular mechanism underlying glucose metabolism reprogramming remains elusive. The aim of this study was to elucidate the role of Yes-associated protein (YAP1), an important effector of the Hippo pathway, in the regulation of aerobic glycolysis in pancreatic cancer. Moreover, the contributions of YAP1 and its associated glycolytic enzymes to prognosis were assessed via The Cancer Genome Atlas (TCGA) dataset.

METHODS

YAP1 expression was silenced by short hairpin RNA (shRNA), and its effects on glycolytic activity and mitochondrial respiration were analysed via Agilent Seahorse XF Analysers. The effects of YAP1 on hypoxia-inducible factor-1α (HIF-1α) and its transcriptional activity on glycolytic genes were examined via shRNA-mediated silencing of YAP1. The underlying mechanism by which YAP1 controls the HIF-1α protein level was analysed by exploring the interaction between YAP1 and egg-laying-defective nine family (EGLN) members, which are well-established regulators of the HIF-1α protein level. Finally, the effects of YAP1, EGLN and glycolytic genes on prognosis were analysed via TCGA dataset.

RESULTS

We found that silencing YAP1 expression inhibited anabolic glycolysis in pancreatic cancer cells. YAP1 was demonstrated to regulate the HIF-1α protein level, transcriptional activity and the expression of HIF-1α-targeted glycolytic genes. In-depth analysis demonstrated that EGLN2, a modulator of the HIF-1α protein level, was a direct target of YAP1. Low EGLN2 expression was associated with a poor prognosis. By analysing TCGA dataset and performing immunohistochemical staining, we demonstrated that YAP1 expression was negatively correlated with EGLN2 expression at the mRNA level and protein levels.

CONCLUSIONS

The present study demonstrated that YAP1 positively regulates aerobic glycolysis by inhibiting EGLN2 expression, which results in an increased HIF-1α protein level and transcriptional activity. YAP1 was positively regulated and significantly correlated with HIF-1α-targeted glycolytic genes, including glucose transporter type 1(GLUT1), hexokinase2 (HK2) and lactate dehydrogenase A (LDHA). Elevated YAP1 expression and concomitant downregulation of EGLN2 contributed to poor survival in patients with pancreatic cancer. Our results suggest that YAP1 may be a promising predictive marker and treatment target for human pancreatic cancer.

Synergistic enhancement: Exploring the potential of piperine in cancer therapeutics through chemosensitization and combination therapies

Despite significant advancements in chemotherapy, effective treatments for advanced cancer stages remain largely elusive due to chemoresistance. Resistance to anticancer agents in cancer cells can arise through various mechanisms, including multi-drug resistance, inhibition of apoptosis, modification of drug targets, and enhancement of DNA repair capabilities. Consequently, there is a critical need for agents that can suppress the molecular signatures responsible for drug resistance. Piperine, an active alkaloid extracted from Piper nigrum L. (black pepper), is one such agent that has been extensively studied for its potential in addressing chronic diseases, including cancer. Piperine's antineoplastic properties are mediated through the regulation of numerous key cellular signaling pathways and the modulation of various biological processes. Its capability to enhance drug bioavailability and counteract mechanisms of drug resistance, such as the inhibition of P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP-1), emphasizes its potential as an adjunct in cancer therapy. Research across various cancer types has demonstrated piperine's role in chemosensitization by targeting P-gp and MRP-1 and altering drug-metabolizing enzymes. This review provides a comprehensive analysis of piperine's pharmacological characteristics and its capacity to modulate several cellular signaling pathways involved in drug resistance. Furthermore, the review emphasizes how piperine, when used in conjunction with other chemotherapeutic agents or natural compounds, can enhance therapeutic effects, leading to improved outcomes in cancer treatment.