Kindlin-2 links mechano-environment to proline synthesis and tumor growth

The (un)known crosstalk between metabolism and mechanotransduction: Implications for metabolic syndrome (MetS)-associated neurological complications

Metabolic syndrome (MetS) has been associated with disruptions in tissue mechanical homeostasis and inflammatory and metabolic derangements. However, the direct correlation between metabolic alterations and changes in tissue stiffness, and whether they could play a role as upstream initiators of disease pathology remains to be investigated. This emerging concept has yet to be put into clinical practice as many questions concerning the interplay between extracellular matrix mechanical properties and regulation of metabolic pathways remain unsolved. This review will highlight key foundational studies examining mutual regulation of cell metabolism and mechanotransduction, and opening questions lying ahead for better understanding MetS pathophysiology.

Gastrodin Alleviates Tau Pathology by Targeting the Alzheimer's Risk Gene FERMT2, Reversing the Reduction in Brain Viscoelasticity

BACKGROUND

The pathogenesis of Alzheimer's disease (AD) remains incompletely elucidated, and there is a notable deficiency in effective and safe therapeutic interventions. The influence of brain matrix viscoelasticity on the progression of AD has frequently been underestimated. It is imperative to elucidate these overlooked pathogenic factors and to innovate novel therapeutic strategies for AD. Gastrodin, a bioactive constituent derived from the traditional Chinese medicinal herb Gastrodia elata, exhibits a range of pharmacological properties, notably in the enhancement of neural function. Nevertheless, the underlying mechanisms of its action remain insufficiently elucidated. Consequently, this study seeks to examine the therapeutic effects and underlying mechanisms of gastrodin in the context of AD, with particular emphasis on its potential influence on the viscoelastic properties of the brain matrix.

METHODS

This study employs a range of methodologies, including the Morris water maze test, Y-maze spontaneous alternation test, atomic force microscopy (AFM), immunofluorescence, transmission electron microscopy, molecular docking, and Cellular Thermal Shift Assay (CETSA), to demonstrate that gastrodin mitigates tau pathology by modulating FERMT2, thereby reversing the deterioration of mechanical viscoelasticity in the brain.

RESULTS

Gastrodin administration via gavage has been demonstrated to mitigate cognitive decline associated with AD, attenuate the hyperphosphorylation of tau protein in the hippocampus and cortex, and ameliorate synaptic damage. Additionally, gastrodin was observed to counteract the reduction in brain matrix viscoelasticity in 3xTg-AD mice, as evidenced by the upregulation of extracellular matrix components pertinent to viscoelasticity, notably collagen types I and IV. Furthermore, molecular docking and CETSA revealed a strong binding affinity between gastrodin and FERMT2. Gastrodin treatment resulted in a reduction of FERMT2 fluorescence intensity, which is selectively expressed in astrocytes. Additionally, gastrodin contributed to the restoration of the blood-brain barrier (BBB) and modulated the expression levels of inflammatory mediators interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and matrix metallopeptidase 8 (MMP8).

CONCLUSION

Gastrodin treatment has the potential to mitigate tau pathology, thereby enhancing learning and memory in AD mouse models. This effect may be mediated through the modulation of cerebral mechanical viscoelasticity via the mechanosensor FERMT2, which facilitates the restoration of synaptic structure and function. This process is potentially linked to the maintenance of BBB integrity and the modulation of inflammatory factor release.

PYCR1 Promotes Esophageal Squamous Cell Carcinoma by Interacting With EGFR to Affecting the PI3K/Akt/mTOR Signaling Pathway

BACKGROUND

The expression and functional role of pyrroline-5-carboxylate reductase 1 (PYCR1) in esophageal squamous cell carcinoma (ESCC) remain poorly understood. This study aimed to elucidate the role and underlying mechanisms of PYCR1 in ESCC.

METHODS

We utilized an ESCC tissue microarray coupled with immunohistochemical staining to assess variability in PYCR1 protein expression among ESCC patients and evaluate its clinical relevance. PYCR1 was silenced in ESCC cell lines with short hairpin RNA (shRNA), followed by functional assays (colony formation, caspase 3/7 activity, methylthiazol tetrazolium, wound healing, and migration/invasion assays) to evaluate its role in ESCC progression. In vivo, mouse tumor xenograft models were used to examine PYCR1's impact on tumor growth. To identify downstream targets and pathways, we conducted coimmunoprecipitation, mass spectrometry, immunofluorescence, and proteomic analyses, validated by western blotting and rescue experiments.

RESULTS

Our findings demonstrated a consistent upregulation of PYCR1 in ESCC tissues. Both in vitro and in vivo studies revealed that PYCR1 suppression significantly inhibited ESCC progression, impacting key processes such as proliferation, apoptosis, migration, and invasion. Mechanistically, PYCR1 was shown to interact with EGFR, promoting ESCC progression and metastasis by activating the PI3K/AKT/mTOR signaling pathways, which are integral to the aggressive behavior of the disease. Rescue experiments further confirmed that EGFR overexpression effectively reversed the inhibitory effects of PYCR1 knockdown in ESCC cells.

CONCLUSION

This study highlights the critical role of PYCR1 in driving ESCC progression and metastasis, underscoring its potential as a promising therapeutic target for managing this malignancy.

Mesenchymal stromal cells promote the formation of lung cancer organoids via Kindlin-2

BACKGROUND

Patient-derived lung cancer organoids (PD-LCOs) demonstrate exceptional potential in preclinical testing and serve as a promising model for the multimodal management of lung cancer. However, certain lung cancer cells derived from patients exhibit limited capacity to generate organoids due to inter-tumor or intra-tumor variability. To overcome this limitation, we have created an in vitro system that employs mesenchymal stromal cells (MSCs) or fibroblasts to serve as a supportive scaffold for lung cancer cells that do not form organoids.

METHODS

We successfully established an MSCs/fibroblast co-culture system to form LCOs. We analyzed the morphological and histological similarities between LCOs co-cultured with fibroblast and primary lung cancer lesions through HE and IF staining. We evaluated whether LCOs co-cultured with fibroblast retained the original genetic mutations of their source tumors based on WES. RNA sequencing was used to analyze the differences in gene expression profiles between LCOs co-cultured with fibroblast and paracancerous organoids (POs). Importantly, we have successfully validated the impact of Kindlin-2 on the regulation of MSCs in organoid formation through lentiviral vector-mediated interference or overexpression of kindlin-2.

RESULTS

Our findings demonstrate that the addition of MSCs/fibroblasts to three tumor samples, initially incapable of forming organoids by traditional methods, successfully facilitated the cultivation of tumor organoids. Importantly, these organoids co-cultured with fibroblast faithfully recapitulate the tissue morphology of original lung tumors and replicate the genetic profile observed in the parental tumors even after prolonged in vitro culture. Moreover, drug responses exhibited by these organoids co-cultured with MSCs/fibroblasts are consistent with those observed in the original tumors. Mechanistically, we have also identified kindlin-2 as a crucial regulator linking extracellular matrix (ECM) and mitochondria that influence MSC/fibroblast-mediated support for tumor organoid formation.

CONCLUSION

The results obtained from our research enhance the understanding of the mechanisms implicated in the formation of tumor organoids and aid in creating stronger patient-specific tumor organoid models. This advancement supports the refinement of personalized drug response assessments for use in clinical settings.

Migfilin promotes autophagic flux through direct interaction with SNAP29 and Vamp8

Autophagy plays a crucial role in cancer cell survival by facilitating the elimination of detrimental cellular components and the recycling of nutrients. Understanding the molecular regulation of autophagy is critical for developing interventional approaches for cancer therapy. In this study, we report that migfilin, a focal adhesion protein, plays a novel role in promoting autophagy by increasing autophagosome-lysosome fusion. We found that migfilin is associated with SNAP29 and Vamp8, thereby facilitating Stx17-SNAP29-Vamp8 SNARE complex assembly. Depletion of migfilin disrupted the formation of the SNAP29-mediated SNARE complex, which consequently blocked the autophagosome-lysosome fusion, ultimately suppressing cancer cell growth. Restoration of the SNARE complex formation rescued migfilin-deficiency-induced autophagic flux defects. Finally, we found depletion of migfilin inhibited cancer cell proliferation. SNARE complex reassembly successfully reversed migfilin-deficiency-induced inhibition of cancer cell growth. Taken together, our study uncovers a new function of migfilin as an autophagy-regulatory protein and suggests that targeting the migfilin-SNARE assembly could provide a promising therapeutic approach to alleviate cancer progression.

Integrating metabolomics and network pharmacology analysis to explore mechanism of Pueraria lobata against pulmonary fibrosis: Involvement of arginine metabolism pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Pueraria lobata (Willd.) Ohwi is a typical medicinal and edible plant with a long application history in China and Southeast Asia. As a widely used traditional medicine, P. lobata exhibits the properties of anti-inflammatory, antipyretic, antioxidant, relieving cough and asthma. Particularly, the increasing evidence indicates that the P. lobata has the therapeutic effect on fibrotic-related diseases in terms of metabolic regulation. However, the mechanisms of P. lobata on pulmonary fibrosis (PF) has not been thoroughly explored.

AIM OF THE STUDY

This study aimed to explore the effect of arginine metabolites of P. lobata against PF model by integrating metabolomics and network pharmacology analysis. It might provide a new idea for the target finding of P. lobata anti-pulmonary fibrosis.

MATERIALS AND METHODS

In this study, the Sprague Dawley (SD) rats were randomly divided into five experimental groups: saline-treated control group, bleomycin-induced fibrosis group, prednisolone acetate group, P. lobata 3.2 g/kg group and P. lobata 6.4 g/kg group. The therapeutic effect of P. lobata on bleomycin-induced PF in rats was evaluated by clinical symptoms such as lung function, body weight, hematoxylin eosin staining (HE), Masson staining and hydroxyproline assay. Next, the plasma metabolomics analysis was carried out by LC-MS to explore the pathological differences between the group of control, PF and P. lobata-treated rats. Then, the network pharmacology study coupled with experimental validation was conducted to analysis the results of metabolic research. We constructed the "component-target-disease" network of P. lobata in the treatment of PF. In addition, the molecular docking method was used to verify the interaction between potential active ingredients and core targets of P. lobata. Finally, we tested NOS2 and L-OT in arginine-related metabolic pathway in plasma of the rats by enzyme-linked immunosorbent assay (ELISA). Real-time PCR was performed to observe the level of TNF-α mRNA and MMP9 mRNA. And we tested the expression of TNF-α and MMP9 by Western blot analysis.

RESULTS

Our findings revealed that P. lobata improved lung function and ameliorated the pathological symptoms, such as pathological damage, collagen deposition, and body weight loss in PF rats. Otherwise, the plasma metabolomics were employed to screen the differential metabolites of amino acids, lipids, flavonoids, arachidonic acid metabolites, glycoside, etc. Finally, we found that the arginine metabolism signaling mainly involved in the regulating of P. lobata on the treatment of PF rats. Furtherly, the network pharmacology predicted that the arginine metabolism pathway was contained in the top 20 pathways. Next, we integrated metabolomics and network pharmacology that identified NOS2, MMP9 and TNF-α as the P. lobata regulated hub genes by molecular docking. Importantly, it indicated a strong affinity between the puerarin and the NOS2. P. lobata attenuated TNF-α, MMP-9 and NOS2 levels, suppressed TNF-α and MMP-9 protein expression, and decreased L-OT and NOS2 content in PF rats. These results indicated that the effects of P. lobata may ameliorated PF via the arginine metabolism pathway in rats. Therefore, P. lobata may be a potential therapeutic agent to ameliorated PF.

CONCLUSION

In this work, we used metabolomics and network pharmacology to explore the mechanisms of P. lobata in the treatment of PF. Finally, we confirmed that P. lobata alleviated BLM-induced PF in rats by regulating arginine metabolism pathway based on reducing the L-OT and NOS2-related signal molecular. The search for the biomarkers finding of arginine metabolism pathway revealed a new strategy for P. lobata in the treatment of PF.

The study on 4D culture system of squamous cell carcinoma of tongue

Traditional cell culture methods often fail to accurately replicate the intricate microenvironments crucial for studying specific cell growth patterns. In our study, we developed a 4D cell culture model-a precision instrument comprising an electromagnet, a force transducer, and a cantilever bracket. The experimental setup involves placing a Petri dish above the electromagnet, where gel beads encapsulating magnetic nanoparticles and tongue cancer cells are positioned. In this model, a magnetic force is generated on the magnetic nanoparticles in the culture medium to drive the gel to move and deform when the magnet is energized, thereby exerting an external force on the cells. This setup can mimic the microenvironment of tongue squamous cell carcinoma CAL-27 cells under mechanical stress induced by tongue movements. Electron microscopy and rheological analysis were performed on the hydrogels to confirm the porosity of alginate and its favorable viscoelastic properties. Additionally, Calcein-AM/PI staining was conducted to verify the biosafety of the hydrogel culture system. It mimics the microenvironment where tongue squamous cell carcinoma CAL-27 cells are stimulated by mechanical stress during tongue movement. Electron microscopy and rheological analysis experiments were conducted on hydrogels to assess the porosity of alginate and its viscoelastic properties. Calcein-AM/PI staining was performed to evaluate the biosafety of the hydrogel culture system. We confirmed that the proliferation of CAL-27 tongue squamous cells significantly increased with increased matrix stiffness after 5 d as assessed by MTT. After 15 d of incubation, the tumor spheroid diameter of the 1%-4D group was larger than that of the hydrogel-only culture. The Transwell assay demonstrated that mechanical stress stimulation and increased matrix stiffness could enhance cell aggressiveness. Flow cytometry experiments revealed a decrease in the number of cells in the resting or growth phase (G0/G1 phase), coupled with an increase in the proportion of cells in the preparation-for-division phase (G2/M phase). RT-PCR confirmed decreased expression levels of P53 and integrinβ3 RNA in the 1%-4D group after 21 d of 4D culture, alongside significant increases in the expression levels of Kindlin-2 and integrinαv. Immunofluorescence assays confirmed that 4D culture enhances tissue oxygenation and diminishes nuclear aggregation of HIF-1α. This device mimics the microenvironment of tongue cancer cells under mechanical force and increased matrix hardness during tongue movement, faithfully reproducing cell growthin vivo, and offering a solid foundation for further research on the pathogenic matrix of tongue cancer and drug treatments.

Deubiquitinase USP9x regulates the proline biosynthesis pathway in non-small cell lung cancer

Metabolic rewiring has been recognized as a hallmark of malignant transformation, supplying the biosynthetic and energetic demands for rapid cancer cell proliferation and tumor progression. A comprehensive understanding of the regulatory mechanisms governing these metabolic processes is still limited. Here, we identify the deubiquitinase ubiquitin-specific peptidase 9 X-linked (USP9x) as a positive regulator of the proline biosynthesis pathway in non-small cell lung cancer (NSCLC). Our findings demonstrate USP9x directly stabilizes pyrroline-5-carboxylate reductase 3 (PYCR3), a key enzyme in the proline cycle. Disruption of proline biosynthesis by either USP9x or PYCR3 knockdown influences the proline cycle leading to a decreased activity of the connected pentose phosphate pathway and mitochondrial respiration. We show that USP9x is elevated in human cancer tissues and its suppression impairs NSCLC growth in vitro and in vivo. Overall, our study uncovers a novel function of USP9x as a regulator of the proline biosynthesis pathway, which impacts lung cancer growth and progression, and implicates a new potential therapeutic avenue.

Mechanical regulation of mitochondrial morphodynamics in cancer cells by extracellular microenvironment

Recently, it has been recognized that physical abnormalities (e.g. elevated solid stress, elevated interstitial fluid pressure, increased stiffness) are associated with tumor progression and development. Additionally, these mechanical forces originating from tumor cell environment through mechanotransduction pathways can affect metabolism. On the other hand, mitochondria are well-known as bioenergetic, biosynthetic, and signaling organelles crucial for sensing stress and facilitating cellular adaptation to the environment and physical stimuli. Disruptions in mitochondrial dynamics and function have been found to play a role in the initiation and advancement of cancer. Consequently, it is logical to hypothesize that mitochondria dynamics subjected to physical cues may play a pivotal role in mediating tumorigenesis. Recently mitochondrial biogenesis and turnover, fission and fusion dynamics was linked to mechanotransduction in cancer. However, how cancer cell mechanics and mitochondria functions are connected, still remain poorly understood. Here, we discuss recent studies that link mechanical stimuli exerted by the tumor cell environment and mitochondria dynamics and functions. This interplay between mechanics and mitochondria functions may shed light on how mitochondria regulate tumorigenesis.

UHPLC-HRMS-based Multiomics to Explore the Potential Mechanisms and Biomarkers for Colorectal Cancer

BACKGROUND

Understanding the metabolic changes in colorectal cancer (CRC) and exploring potential diagnostic biomarkers is crucial for elucidating its pathogenesis and reducing mortality. Cancer cells are typically derived from cancer tissues and can be easily obtained and cultured. Systematic studies on CRC cells at different stages are still lacking. Additionally, there is a need to validate our previous findings from human serum.

METHODS

Ultrahigh-performance liquid chromatography tandem high-resolution mass spectrometry (UHPLC-HRMS)-based metabolomics and lipidomics were employed to comprehensively measure metabolites and lipids in CRC cells at four different stages and serum samples from normal control (NR) and CRC subjects. Univariate and multivariate statistical analyses were applied to select the differential metabolites and lipids between groups. Biomarkers with good diagnostic efficacy for CRC that existed in both cells and serum were screened by the receiver operating characteristic curve (ROC) analysis. Furthermore, potential biomarkers were validated using metabolite standards.

RESULTS

Metabolite and lipid profiles differed significantly among CRC cells at stages A, B, C, and D. Dysregulation of glycerophospholipid (GPL), fatty acid (FA), and amino acid (AA) metabolism played a crucial role in the CRC progression, particularly GPL metabolism dominated by phosphatidylcholine (PC). A total of 46 differential metabolites and 29 differential lipids common to the four stages of CRC cells were discovered. Eight metabolites showed the same trends in CRC cells and serum from CRC patients compared to the control groups. Among them, palmitoylcarnitine and sphingosine could serve as potential biomarkers with the values of area under the curve (AUC) more than 0.80 in the serum and cells. Their panel exhibited excellent performance in discriminating CRC cells at different stages from normal cells (AUC = 1.00).

CONCLUSIONS

To our knowledge, this is the first research to attempt to validate the results of metabolism studies of serum from CRC patients using cell models. The metabolic disorders of PC, FA, and AA were closely related to the tumorigenesis of CRC, with PC being the more critical factor. The panel composed of palmitoylcarnitine and sphingosine may act as a potential biomarker for the diagnosis of CRC, aiding in its prevention.

TSPAN8+ myofibroblastic cancer-associated fibroblasts promote chemoresistance in patients with breast cancer

Cancer-associated fibroblasts (CAFs) are abundant stromal cells in the tumor microenvironment that promote cancer progression and relapse. However, the heterogeneity and regulatory roles of CAFs underlying chemoresistance remain largely unclear. Here, we performed a single-cell analysis using high-dimensional flow cytometry analysis and identified a distinct senescence-like tetraspanin-8 (TSPAN8)+ myofibroblastic CAF (myCAF) subset, which is correlated with therapeutic resistance and poor survival in multiple cohorts of patients with breast cancer (BC). TSPAN8+ myCAFs potentiate the stemness of the surrounding BC cells through secretion of senescence-associated secretory phenotype (SASP)-related factors IL-6 and IL-8 to counteract chemotherapy. NAD-dependent protein deacetylase sirtuin 6 (SIRT6) reduction was responsible for the senescence-like phenotype and tumor-promoting role of TSPAN8+ myCAFs. Mechanistically, TSPAN8 promoted the phosphorylation of ubiquitin E3 ligase retinoblastoma binding protein 6 (RBBP6) at Ser772 by recruiting MAPK11, thereby inducing SIRT6 protein destruction. In turn, SIRT6 down-regulation up-regulated GLS1 and PYCR1, which caused TSPAN8+ myCAFs to secrete aspartate and proline, and therefore proved a nutritional niche to support BC outgrowth. By demonstrating that TSPAN8+SIRT6low myCAFs were tightly associated with unfavorable disease outcomes, we proposed that the combined regimen of anti-TSPAN8 antibody and SIRT6 activator MDL-800 is a promising approach to overcome chemoresistance. These findings highlight that senescence contributes to CAF heterogeneity and chemoresistance and suggest that targeting TSPAN8+ myCAFs is a promising approach to circumvent chemoresistance.

Pan-cancer analyses suggest kindlin-associated global mechanochemical alterations

Kindlins serve as mechanosensitive adapters, transducing extracellular mechanical cues to intracellular biochemical signals and thus, their perturbations potentially lead to cancer progressions. Despite the kindlin involvement in tumor development, understanding their genetic and mechanochemical characteristics across different cancers remains elusive. Here, we thoroughly examined genetic alterations in kindlins across more than 10,000 patients with 33 cancer types. Our findings reveal cancer-specific alterations, particularly prevalent in advanced tumor stage and during metastatic onset. We observed a significant co-alteration between kindlins and mechanochemical proteome in various tumors through the activation of cancer-related pathways and adverse survival outcomes. Leveraging normal mode analysis, we predicted structural consequences of cancer-specific kindlin mutations, highlighting potential impacts on stability and downstream signaling pathways. Our study unraveled alterations in epithelial-mesenchymal transition markers associated with kindlin activity. This comprehensive analysis provides a resource for guiding future mechanistic investigations and therapeutic strategies targeting the roles of kindlins in cancer treatment.

Kindlin-2 maintains liver homeostasis by regulating GSTP1-OPN-mediated oxidative stress and inflammation in mice

Hepatocyte plays a principal role in preserving integrity of the liver homeostasis. Our recent study demonstrated that Kindlin-2, a focal adhesion protein that activates integrins and regulates cell-extracellular matrix interactions, plays an important role in regulation of liver homeostasis by inhibiting inflammation pathway; however, the molecular mechanism of how Kindlin-2 KO activates inflammation is unknown. Here, we show that Kindlin-2 loss largely downregulates the antioxidant glutathione-S-transferase P1 in hepatocytes by promoting its ubiquitination and degradation via a mechanism involving protein-protein interaction. This causes overproduction of intracellular reactive oxygen species and excessive oxidative stress in hepatocytes. Kindlin-2 loss upregulates osteopontin in hepatocytes partially because of upregulation of reactive oxygen species and consequently stimulates overproduction of inflammatory cytokines and infiltration in liver. The molecular and histological deteriorations caused by Kindlin-2 deficiency are markedly reversed by systemic administration of an antioxidant N-acetylcysteine in mice. Taken together, Kindlin-2 plays a pivotal role in preserving integrity of liver function.

Proline metabolism shapes the tumor microenvironment: from collagen deposition to immune evasion

Proline is a nonessential amino acid, and its metabolism has been implicated in numerous malignancies. Together with a direct role in regulating cancer cells' proliferation and survival, proline metabolism plays active roles in shaping the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) display high rates of proline biosynthesis to support the production of collagen for the extracellular matrix (ECM). Indeed, impaired proline metabolism in CAFs results in reduced collagen deposition and compromises the growth and metastatic spread of cancer. Moreover, the rate of proline metabolism regulates intracellular reactive oxygen species (ROS) levels, which influence the production and release of cytokines from cancer cells, contributing toward an immune-permissive TME. Hence, targeting proline metabolism is a promising anticancer strategy that could improve patients' outcome and response to immunotherapy.

Pyrroline-5-carboxylate reductase 1 reprograms proline metabolism to drive breast cancer stemness under psychological stress

Cancer stem-like cells (CSCs) contribute to cancer metastasis, drug resistance and tumor relapse, yet how amino acid metabolism promotes CSC maintenance remains exclusive. Here, we identify that proline synthetase PYCR1 is critical for breast cancer stemness and tumor growth. Mechanistically, PYCR1-synthesized proline activates cGMP-PKG signaling to enhance cancer stem-like traits. Importantly, cGMP-PKG signaling mediates psychological stress-induced cancer stem-like phenotypes and tumorigenesis. Ablation of PYCR1 markedly reverses psychological stress-induced proline synthesis, cGMP-PKG signaling activation and cancer progression. Clinically, PYCR1 and cGMP-PKG signaling components are highly expressed in breast tumor specimens, conferring poor survival in breast cancer patients. Targeting proline metabolism or cGMP-PKG signaling pathway provides a potential therapeutic strategy for breast patients undergoing psychological stress. Collectively, our findings unveil that PYCR1-enhanced proline synthesis displays a critical role in maintaining breast cancer stemness.

Dynamic links between mechanical forces and metabolism shape the tumor milieu

Cell function relies on the spatiotemporal dynamics of metabolic reactions. In all physiopathological processes of tissues, mechanical forces impact the structure and function of membranes, enzymes, organelles and regulators of metabolic gene programs, thus regulating cell metabolism. In turn, metabolic pathways feedback impacts the physical properties of cell and tissues. Hence, metabolism and tissue mechanics are dynamically intertwined and continuously interact. Cancer is akin to an ecosystem, comprising tumor cells and various subpopulations of stromal cells embedded in an altered extracellular matrix. The progression of cancer, from initiation to advanced stage and metastasis, is driven by genetic mutations and crucially influenced by physical and metabolic alterations in the tumor microenvironment. These alterations also play a pivotal role in cancer cells evasion from immune surveillance and in developing resistance to treatments. Here, we highlight emerging evidence showing that mechano-metabolic circuits in cancer and stromal cells regulate multiple processes crucial for tumor progression and discuss potential approaches to improve therapeutic treatments by interfering with these circuits.

Loss of Pinch Proteins Causes Severe Degenerative Disc Disease-Like Lesions in Mice

Degenerative disc disease (DDD) is one of the most common skeletal disorders affecting aged populations. DDD is the leading cause of low back/neck pain, resulting in disability and huge socioeconomic burdens. However, the molecular mechanisms underlying DDD initiation and progression remain poorly understood. Pinch1 and Pinch2 are LIM-domain-containing proteins with crucial functions in mediating multiple fundamental biological processes, such as focal adhesion, cytoskeletal organization, cell proliferation, migration, and survival. In this study, we found that Pinch1 and Pinch2 were both highly expressed in healthy intervertebral discs (IVDs) and dramatically downregulated in degenerative IVDs in mice. Deleting Pinch1 in aggrecan-expressing cells and Pinch2 globally (AggrecanCreERT2; Pinch1fl/fl; Pinch2-/-) caused striking spontaneous DDD-like lesions in lumbar IVDs in mice. Pinch loss inhibited cell proliferation and promoted extracellular matrix (ECM) degradation and apoptosis in lumbar IVDs. Pinch loss markedly enhanced the production of pro-inflammatory cytokines, especially TNFα, in lumbar IVDs and exacerbated instability-induced DDD defects in mice. Pharmacological inhibition of TNFα signaling mitigated the DDD-like lesions caused by Pinch loss. In human degenerative NP samples, reduced expression of Pinch proteins was correlated with severe DDD progression and a markedly upregulated expression of TNFα. Collectively, we demonstrate the crucial role of Pinch proteins in maintaining IVD homeostasis and define a potential therapeutic target for DDD.

Mechanical stiffness promotes skin fibrosis through Piezo1-mediated arginine and proline metabolism

The increased mechanics of fibrotic skin tissue continuously regulate fibroblast functions such as survival and differentiation. Although all these processes consume metabolites, it is unclear whether and how cells adapt their metabolic activity to increased matrix stiffness. Here, we show that transferring mouse dermal fibroblasts from soft to stiff substrates causes an up-regulation of arginine and proline metabolism. Increased matrix stiffness stimulates the expression and activity of key metabolic enzymes, leading to the synthesis of L-proline, a major source of collagen. In addition, the novel mechanosensitive channel Piezo1 was identified as a key regulator of arginine and proline metabolism in fibroblasts under increased stiffness. Consistently, targeting Piezo1 to dermal fibroblasts in vivo effectively reduces fibrosis and arginine-proline metabolism in mouse skin. Therefore, mechanical stiffness is a critical environmental cue for fibroblast metabolism and skin fibrosis progression.

Effects of PYCR1 on prognosis and immunotherapy plus tyrosine kinase inhibition responsiveness in metastatic renal cell carcinoma patients

BACKGROUND

Immunotherapy plus tyrosine kinase inhibitor (IO-TKI) has become the first-line management for metastatic renal cell carcinoma (RCC), despite the absence of biomarkers. Recently, pyrroline-5-carboxylate reductase 1 (PYCR1) and proline metabolism have been reported regulatory roles in the anti-tumor response.

METHODS

There were three cohorts enrolled: two from our institution (ZS-MRCC and ZS-HRRCC) and one from a clinical trial (JAVELIN-101). The PYCR1expression in each sample was evaluated by RNA sequencing. Flow cytometry and immunohistochemistry were performed to assess immune infiltration. Single-cell RNA-seq (scRNA-seq) data was used for cluster analysis of T cells and macrophages. Primary endpoints were set as response and progression-free survival (PFS).

RESULTS

Patients in the low-PYCR1 group had greater objective response rate (52.2% vs 18.2%) and longer PFS in both cohorts (ZS-MRCC cohort, P=0.01, HR=2.80; JAVELIN-101 cohort, P<0.001, HR=1.85). In responders, PYCR1 expression was decreased (P<0.05). In the high PYCR1 group, CD8+ T cells exhibited an exhausted phenotype with decreased GZMB (Spearman's ρ=-0.36, P=0.02). scRNA-seq revealed tissue-resident memory T (Trm) (P<0.05) and tissue-resident macrophage (P<0.01) were decreased in samples with high PYCR1 expression. A machine learning score was further built by random forest, involving PYCR1 and Trm markers. Only in the subgroup with the lower RFscore did IO+TKI show a favorable outcome, compared to TKI monotherapy.

CONCLUSIONS

Immunosuppression and IO+TKI resistance were correlated with high PYCR1 expression. T cell exhaustion and dysfunction were also related with the expression of PYCR1. PYCR1 has the potential to be employed as a biomarker to discriminate between IO+TKI and TKI monotherapy as the optimal patient treatment strategy.

Proline is increased in allergic asthma and promotes airway remodeling

Proline and its synthesis enzyme pyrroline-5-carboxylate reductase 1 (PYCR1) are implicated in epithelial-mesenchymal transition (EMT), yet how proline and PYCR1 function in allergic asthmatic airway remodeling via EMT has not yet been addressed to our knowledge. In the present study, increased levels of plasma proline and PYCR1 were observed in patients with asthma. Similarly, proline and PYCR1 in lung tissues were high in a murine allergic asthma model induced by house dust mites (HDMs). Pycr1 knockout decreased proline in lung tissues, with reduced airway remodeling and EMT. Mechanistically, loss of Pycr1 restrained HDM-induced EMT by modulating mitochondrial fission, metabolic reprogramming, and the AKT/mTORC1 and WNT3a/β-catenin signaling pathways in airway epithelial cells. Therapeutic inhibition of PYCR1 in wild-type mice disrupted HDM-induced airway inflammation and remodeling. Deprivation of exogenous proline relieved HDM-induced airway remodeling to some extent. Collectively, this study illuminates that proline and PYCR1 involved with airway remodeling in allergic asthma could be viable targets for asthma treatment.

Kindlin-2 enhances c-Myc translation through association with DDX3X to promote pancreatic ductal adenocarcinoma progression

Rationale: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive solid tumor, with extremely low survival rates. Identifying key signaling pathways driving PDAC progression is crucial for the development of therapies to improve patient response rates. Kindlin-2, a multi-functional protein, is involved in numerous biological processes including cell proliferation, apoptosis and migration. However, little is known about the functions of Kindlin-2 in pancreatic cancer progression in vivo. Methods: In this study, we employ an in vivo PDAC mouse model to directly investigate the role of Kindlin-2 in PDAC progression. Then, we utilized RNA-sequencing, the molecular and cellular assays to determine the molecular mechanisms by which Kindlin-2 promotes PDAC progression. Results: We show that loss of Kindlin-2 markedly inhibits KrasG12D-driven pancreatic cancer progression in vivo as well as in vitro. Furthermore, we provide new mechanistic insight into how Kindlin-2 functions in this process, A fraction of Kindlin-2 was localized to the endoplasmic reticulum and associated with the RNA helicase DDX3X, a key regulator of mRNA translation. Loss of Kindlin-2 blocked DDX3X from binding to the 5'-untranslated region of c-Myc and inhibited DDX3X-mediated c-Myc translation, leading to reduced c-Myc-mediated glucose metabolism and tumor growth. Importantly, restoration of the expression of either the full-length Kindlin-2 or c-Myc, but not that of a DDX3X-binding-defective mutant of Kindlin-2, in Kindlin-2 deficient PDAC cells, reversed the inhibition of glycolysis and pancreatic cancer progression induced by the loss of Kindlin-2. Conclusion: Our studies reveal a novel Kindlin-2-DDX3X-c-Myc signaling axis in PDAC progression and suggest that inhibition of this signaling axis may provide a promising therapeutic approach to alleviate PDAC progression.

Kindlin-2 controls angiogenesis through modulating Notch1 signaling

Kindlin-2 is critical for development and homeostasis of key organs, including skeleton, liver, islet, etc., yet its role in modulating angiogenesis is unknown. Here, we report that sufficient KINDLIN-2 is extremely important for NOTCH-mediated physiological angiogenesis. The expression of KINDLIN-2 in HUVECs is significantly modulated by angiogenic factors such as vascular endothelial growth factor A or tumor necrosis factor α. A strong co-localization of CD31 and Kindlin-2 in tissue sections is demonstrated by immunofluorescence staining. Endothelial-cell-specific Kindlin-2 deletion embryos die on E10.5 due to hemorrhage caused by the impaired physiological angiogenesis. Experiments in vitro show that vascular endothelial growth factor A-induced multiple functions of endothelial cells, including migration, matrix proteolysis, morphogenesis and sprouting, are all strengthened by KINDLIN-2 overexpression and severely impaired in the absence of KINDLIN-2. Mechanistically, we demonstrate that KINDLIN-2 inhibits the release of Notch intracellular domain through binding to and maintaining the integrity of NOTCH1. The impaired angiogenesis and avascular retinas caused by KINDLIN-2 deficiency can be rescued by DAPT, an inhibitor of γ-secretase which releases the intracellular domain from NOTCH1. Moreover, we demonstrate that high glucose stimulated hyperactive angiogenesis by increasing KINDLIN-2 expression could be prevented by KINDLIN-2 knockdown, indicating Kindlin-2 as a potential therapeutic target in treatment of diabetic retinopathy. Our study for the first time demonstrates the significance of Kindlin-2 in determining Notch-mediated angiogenesis during development and highlights Kindlin-2 as the potential therapeutic target in angiogenic diseases, such as diabetic retinopathy.

Whole-genome DNA methylation and DNA methylation-based biomarkers in lung squamous cell carcinoma

Exploring early detection methods through comprehensive evaluation of DNA methylation for lung squamous cell carcinoma (LUSC) patients is of great significance. By using different machine learning algorithms for feature selection and model construction based on The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, five methylation biomarkers in LUSC (along with mapped genes) were identified including cg14823851 (TBX4), cg02772121 (TRIM15), cg10424681 (C6orf201), cg12910906 (ARHGEF4), and cg20181079 (OR4D11), achieving extremely high sensitivity and specificity in distinguishing LUSC from normal samples in independent cohorts. Pyrosequencing assay verified DNA methylation levels, meanwhile qRT-PCR and immunohistochemistry results presented their accordant methylation-related gene expression statuses in paired LUSC and normal lung tissues. The five methylation-based biomarkers proposed in this study have great potential for the diagnosis of LUSC and could guide studies in methylation-regulated tumor development and progression.

Amino acid metabolism in tumor: New shine in the fog?

Alterations in amino acid metabolism is closely related to the occurrence of clinical diseases. The mechanism of tumorigenesis is complex, involving the complicated relationship between tumor cells and immune cells in local tumor microenvironment. A series of recent studies have shown that metabolic remodeling is intimately related to tumorigenesis. And amino acid metabolic reprogramming is one of the important characteristics of tumor metabolic remodeling, which participates in tumor cells growth, survival as well as the immune cell activation and function in the local tumor microenvironment, thereby affecting tumor immune escape. Recent studies have further shown that controlling the intake of specific amino acids can significantly improve the effect of clinical intervention in tumors, suggesting that amino acid metabolism is gradually becoming one of the new promising targets of clinical intervention in tumors. Therefore, developing new intervention strategies based on amino acid metabolism has broad prospects. In this article, we review the abnormal changes in the metabolism of some typical amino acids, including glutamine, serine, glycine, asparagine and so on in tumor cells and summarize the relationship among amino acid metabolism, tumor microenvironment and the function of T cells. In particular, we discuss the current issues that need to be addressed in the related fields of tumor amino acid metabolism, aiming to provide a theoretical basis for the development of new strategies for clinical interventions in tumors based on amino acid metabolism reprogramming.

ALKBH5-PYCR2 Positive Feedback Loop Promotes Proneural-Mesenchymal Transition Via Proline Synthesis In GBM

AlkB homolog 5, RNA demethylase (ALKBH5) is abnormally highly expressed in glioblastoma multiforme (GBM) and is negatively correlated with overall survival in GBM patients. In this study, we found a new mechanism that ALKBH5 and pyrroline-5-carboxylate reductase 2 (PYCR2) formed a positive feedback loop involved in proline synthesis in GBM. ALKBH5 promoted PYCR2 expression and PYCR2-mediated proline synthesis; while PYCR2 promoted ALKBH5 expression through the AMPK/mTOR pathway in GBM cells. In addition, ALKBH5 and PYCR2 promoted GBM cell proliferation, migration, and invasion, as well as proneural-mesenchymal transition (PMT). Furthermore, proline rescued AMPK/mTOR activation and PMT after silencing PYCR2 expression. Our findings reveal an ALKBH5-PYCR2 axis linked to proline metabolism, which plays an important role in promoting PMT in GBM cells and may be a promising therapeutic pathway for GBM.

P4HA1 activates HMGCS1 to promote nasopharyngeal carcinoma ferroptosis resistance and progression

Ferroptosis is a novel type of iron-dependent regulatory cell death. To date, the regulatory mechanism of ferroptosis in nasopharyngeal carcinoma (NPC) remains poorly understood. In this study, we found that the prolyl 4-hydroxylase (P4H) subunit P4HA1 protects NPC cells from erastin-induced ferroptosis by activating HMGCS1, a key enzyme in the mevalonate pathway. We also found that the P4HA1/HMGCS1 axis promoted NPC cell proliferation in vitro. In vivo, downregulation of the P4HA1/HMGCS1 axis inhibited the growth of NPC cell xenografts and enhanced the inhibitory effect of erastin on tumor growth. Extracellular matrix (ECM) detachment is an important trigger for ferroptosis. We found that the P4HA1/HMGCS1 axis promoted the ferroptosis resistance and survival of ECM-detached NPC cells. In vivo, downregulation of the P4HA1/HMGCS1 axis inhibited the lung colonization of NPC cells and enhanced the inhibitory effect of erastin on NPC lung metastasis. Moreover, the high expression of P4HA1 predicted a poor prognosis and served as a potential independent prognostic factor in patients with NPC. In conclusion, P4HA1 is a novel molecular marker of NPC ferroptosis resistance and a poor prognosis, and the P4HA1/HMGCS1 axis provides a new target for the treatment of NPC progression.

Extracellular-matrix mechanics regulate cellular metabolism: A ninja warrior behind mechano-chemo signaling crosstalk

Mechanical forces are the indispensable constituent of environmental cues, such as gravity, barometric pressure, vibration, and contact with bodies, which are involved in pattern and organogenesis, providing mechanical input to tissues and determining the ultimate fate of cells. Extracellular matrix (ECM) stiffness, the slow elastic force, carries the external physical force load onto the cell or outputs the internal force exerted by the cell and its neighbors into the environment. Accumulating evidence illustrates the pivotal role of ECM stiffness in the regulation of organogenesis, maintenance of tissue homeostasis, and the development of multiple diseases, which is largely fulfilled through its systematical impact on cellular metabolism. This review summarizes the establishment and regulation of ECM stiffness, the mechanisms underlying how ECM stiffness is sensed by cells and signals to modulate diverse cell metabolic pathways, and the physiological and pathological significance of the ECM stiffness-cell metabolism axis.

The Matrix Reloaded-The Role of the Extracellular Matrix in Cancer

As the core component of all organs, the extracellular matrix (ECM) is an interlocking macromolecular meshwork of proteins, glycoproteins, and proteoglycans that provides mechanical support to cells and tissues. In cancer, the ECM can be remodelled in response to environmental cues, and it controls a plethora of cellular functions, including metabolism, cell polarity, migration, and proliferation, to sustain and support oncogenesis. The biophysical and biochemical properties of the ECM, such as its structural arrangement and being a reservoir for bioactive molecules, control several intra- and intercellular signalling pathways and induce cytoskeletal changes that alter cell shapes, behaviour, and viability. Desmoplasia is a major component of solid tumours. The abnormal deposition and composition of the tumour matrix lead to biochemical and biomechanical alterations that determine disease development and resistance to treatment. This review summarises the complex roles of ECM in cancer and highlights the possible therapeutic targets and how to potentially remodel the dysregulated ECM in the future. Furthering our understanding of the ECM in cancer is important as the modification of the ECM will probably become an important tool in the characterisation of individual tumours and personalised treatment options.

Targeting PYCR2 inhibits intraperitoneal metastatic tumors of mouse colorectal cancer in a proline-independent approach

Whether proline deficiency is a metabolic vulnerability in colorectal tumors is unknown. The aim of this study was to investigate the effects of proline metabolism-related genes and exogenous proline on the progression of colorectal cancer (CRC). We aimed to further clarify the role of pyrroline-5-carboxylate reductase (PYCR) 2, a key enzyme of proline synthesis, in the regulation of colorectal intraperitoneal metastatic tumors. This study was carried out based on The Cancer Genome Atlas (TCGA) data, database analysis, single-cell functional analysis, tissue microarray, cell experiments, and animal models. We found that, PYCR2 mRNA and protein levels were upregulated in CRC. The mRNA level of PYCR2 was closely related to the prognosis and tumor metastasis of CRC patients. The upregulated PYCR2 expression was at least partly due to low promoter methylation levels. The nomogram constructed based on PYCR2 expression and clinical characteristics of CRC showed good accuracy in predicting lymph node metastasis. Pycr2 knockdown inhibited epithelial-mesenchymal transition (EMT) of mouse CRC cells. Proline supplementation did not rescue the inhibition of mouse CRC cell proliferation and migration by Pycr2 knockdown. Proline supplementation also did not rescue the suppression of subcutaneous tumors and intraperitoneal metastatic tumors in mice by Pycr2 knockdown. PYCR2 co-expressed genes in TCGA-CRC were enriched in epigenetic modification-related biological processes and molecular functions. Four small molecules with the lowest binding energy to the PYCR2 protein were identified. Collectively, Pycr2 knockdown inhibited mouse CRC progression in a proline-independent approach. PYCR2 may be a promising tumor metastasis predictor and therapeutic target in CRC.

Functional Impact of a Cancer-Related Variant in Human Δ1-Pyrroline-5-Carboxylate Reductase 1

Pyrroline-5-carboxylate reductase (PYCR) is a proline biosynthetic enzyme that catalyzes the NAD(P)H-dependent reduction of Δ¹-pyrroline-5-carboxylate (P5C) to proline. Humans have three PYCR isoforms, with PYCR1 often upregulated in different types of cancers. Here, we studied the biochemical and structural properties of the Thr171Met variant of PYCR1, which is found in patients with malignant melanoma and lung adenocarcinoma. Although PYCR1 is strongly associated with cancer progression, characterization of a PYCR1 variant in cancer patients has not yet been reported. Thr171 is conserved in all three PYCR isozymes and is located near the P5C substrate binding site. We found that the amino acid replacement does not affect thermostability but has a profound effect on PYCR1 catalytic activity. The k _cat of the PYCR1 variant T171M is 100- to 200-fold lower than wild-type PYCR1 when P5C is the variable substrate, and 10- to 25-fold lower when NAD(P)H is varied. A 1.84 Å resolution X-ray crystal structure of T171M reveals that the Met side chain invades the P5C substrate binding site, suggesting that the catalytic defect is due to steric clash preventing P5C from achieving the optimal pose for hydride transfer from NAD(P)H. These results suggest that any impact on PYCR1 function associated with T171M in cancer does not derive from increased catalytic activity.

Metabolomic and transcriptomic studies of improvements in myocardial infarction due to Pycr1 deletion

Myocardial infarction (MI) remains a major challenge to cardiovascular health worldwide, with poor healing leaving a direct impact on patients' quality of life and survival. Metabolic abnormalities after MI are receiving increasing attention. Our previous studies showed that enhancing proline catabolism ameliorates hypoxic damage to myocardial cells; therefore, we sought to determine whether reducing the synthesis of endogenous proline also affects MI. We analysed GEO datasets associated with MI and western blot of mouse heart tissue in an MI model to demonstrate pyrroline-5-carboxylate reductase 1 (Pycr1) expression level after MI. We constructed Pycr1 KO mice by CRISPR/Cas9 technology to explore the effect of Pycr1 gene KO after MI using transcriptomic and metabolomic techniques. In this study, we found reduced mRNA and protein expression levels of Pycr1 in the hearts of mice after MI. We observed that Pycr1 gene KO has a protective effect against MI, reducing the area of MI and improving heart function. Using transcriptomics approaches, we found 215 upregulated genes and 247 downregulated genes after KO of the Pycr1 gene, indicating that unsaturated fatty acid metabolism was affected at the transcriptional level. Metabolomics results revealed elevated content for 141 metabolites and decreased content for 90 metabolites, among which the levels of fatty acids, glycerol phospholipids, bile acids, and other metabolites increased significantly. The changes in these metabolites may be related to the protective effect of Pycr1 KO on the heart after MI. Pycr1 gene KO has a protective effect against MI and our research will lay a solid foundation for the development of future Pycr1-related drug targets.

Mechanobiology of solid tumors

Mechanical features of cancer cells emerge as a distinct trait during development and progression of solid tumors. Herein, we discuss recent key findings regarding the impact of various types of mechanical stresses on cancer cell properties. Data suggest that different mechanical forces, alterations of matrix rigidity and tumor microenvironment facilitate cancer hallmarks, especially invasion and metastasis. Moreover, a subset of mechanosensory proteins are responsible for mediating mechanically induced oncogenic signaling and response to chemotherapy. Delineating cancer dynamics and decoding of respective signal transduction mechanisms will provide new therapeutic strategies against solid tumors in the future.

Integration of stool microbiota, proteome and amino acid profiles to discriminate patients with adenomas and colorectal cancer

BACKGROUND

Screening for colorectal cancer (CRC) reduces its mortality but has limited sensitivity and specificity. Aims We aimed to explore potential biomarker panels for CRC and adenoma detection and to gain insight into the interaction between gut microbiota and human metabolism in the presence of these lesions.

METHODS

This multicenter case-control cohort was performed between February 2016 and November 2019. Consecutive patients ≥18 years with a scheduled colonoscopy were asked to participate and divided into three age, gender, body-mass index and smoking status-matched subgroups: CRC (n = 12), adenomas (n = 21) and controls (n = 20). Participants collected fecal samples prior to bowel preparation on which proteome (LC-MS/MS), microbiota (16S rRNA profiling) and amino acid (HPLC) composition were assessed. Best predictive markers were combined to create diagnostic biomarker panels. Pearson correlation-based analysis on selected markers was performed to create networks of all platforms.

RESULTS

Combining omics platforms provided new panels which outperformed hemoglobin in this cohort, currently used for screening (AUC 0.98, 0.95 and 0.87 for CRC vs controls, adenoma vs controls and CRC vs adenoma, respectively). Integration of data sets revealed markers associated with increased blood excretion, stress- and inflammatory responses and pointed toward downregulation of epithelial integrity.

CONCLUSIONS

Integrating fecal microbiota, proteome and amino acids platforms provides for new biomarker panels that may improve noninvasive screening for adenomas and CRC, and may subsequently lead to lower incidence and mortality of colon cancer.

Metabolomics-based classification reveals subtypes of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death, and the prognosis varies due to its high heterogeneity, systematic evaluation of HCC is mainly based on genomic and transcriptomic features, metabolomics-based classification has yet to be reported. Here we performed RNA-seq on 50 paired samples and metabolomics analysis on 72 paired samples of both normal and tumor tissues from HCC patients. Through unsupervised hierarchical cluster analysis with train and test data sets, metabolic and gene expression signatures were identified. We found that most fluxes related to glutamate are attenuated, except for the glutamate-proline pathway. Three subgroups were identified with distinct survival, clinical observations, and metabolic/gene signatures. S1 is characterized by a relatively poor prognosis, a low concentration of the degradation products of phosphatidylcholine and phosphatidylethanolamine, an enrichment of specific genes related to focal adhesion, and an upregulation of genes on chromosome 6q27. Beyond commonly downregulated metabolites, S2 tumors are largely characterized by few alterations in metabolites and genes, as well as low incidence of mutations/loss of heterozygosity, the metabolite signature of this group consists of hexoses and their phosphates, and the prognosis is the best, with a 5-year survival rate of greater than 80%. S3 is characterized by the worst survival (an approximately 20% 5-year survival rate), unsaturated fatty acid metabolites, an upregulation of specific genes involved in metastasis, and an upregulation of genes on chromosome 1q21. The metabolite-based classifications are more stable and reproducible, with each subgroup characterized by a distinct molecular signature and disease prognosis.

Mitochondrial fragmentation in liver cancer: Emerging player and promising therapeutic opportunities

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related death worldwide. Enhanced mitochondrial fragmentation (MF) is associated with poor prognosis in HCC patients. However, its molecular mechanism in HCC remains elusive. Although enhanced MF activates effector T cells and dendritic cells, it induces immunoescape by decreasing the number and cytotoxicity of natural killer cells in the HCC immune microenvironment. Therefore, the influence of MF on the activity of different immune cells is a great challenge. Enhanced MF contributes to maintaining stemness by promoting the asymmetric division of liver cancer stem cells (LCSCs), suggesting that MF may become a potential target for HCC recurrence, metastasis, and chemotherapy resistance. Moreover, mechanistic studies suggest that MF may promote tumour progression through autophagy, oxidative stress, and metabolic reprogramming. Human-induced hepatocyte organoids are a recently developed system that can be genetically manipulated to mimic cancer initiation and identify potential preventive treatments. We can use it to screen MF-related candidate inhibitors of HCC progression and further explore the role of MF in hepatocarcinogenesis. We herein describe the mechanisms by which MF contributes to HCC development, discuss potential therapeutic approaches, and highlight the possibility that MF modulation has a synergistic effect with immunotherapy.

Kindlin-2 loss in condylar chondrocytes causes spontaneous osteoarthritic lesions in the temporomandibular joint in mice

The progressive destruction of condylar cartilage is a hallmark of the temporomandibular joint (TMJ) osteoarthritis (OA); however, its mechanism is incompletely understood. Here, we show that Kindlin-2, a key focal adhesion protein, is strongly detected in cells of mandibular condylar cartilage in mice. We find that genetic ablation of Kindlin-2 in aggrecan-expressing condylar chondrocytes induces multiple spontaneous osteoarthritic lesions, including progressive cartilage loss and deformation, surface fissures, and ectopic cartilage and bone formation in TMJ. Kindlin-2 loss significantly downregulates the expression of aggrecan, Col2a1 and Proteoglycan 4 (Prg4), all anabolic extracellular matrix proteins, and promotes catabolic metabolism in TMJ cartilage by inducing expression of Runx2 and Mmp13 in condylar chondrocytes. Kindlin-2 loss decreases TMJ chondrocyte proliferation in condylar cartilages. Furthermore, Kindlin-2 loss promotes the release of cytochrome c as well as caspase 3 activation, and accelerates chondrocyte apoptosis in vitro and TMJ. Collectively, these findings reveal a crucial role of Kindlin-2 in condylar chondrocytes to maintain TMJ homeostasis.

Extracellular Matrix Stiffness in Lung Health and Disease

The extracellular matrix (ECM) provides structural support and imparts a wide variety of environmental cues to cells. In the past decade, a growing body of work revealed that the mechanical properties of the ECM, commonly known as matrix stiffness, regulate the fundamental cellular processes of the lung. There is growing appreciation that mechanical interplays between cells and associated ECM are essential to maintain lung homeostasis. Dysregulation of ECM-derived mechanical signaling via altered mechanosensing and mechanotransduction pathways is associated with many common lung diseases. Matrix stiffening is a hallmark of lung fibrosis. The stiffened ECM is not merely a sequelae of lung fibrosis but can actively drive the progression of fibrotic lung disease. In this article, we provide a comprehensive view on the role of matrix stiffness in lung health and disease. We begin by summarizing the effects of matrix stiffness on the function and behavior of various lung cell types and on regulation of biomolecule activity and key physiological processes, including host immune response and cellular metabolism. We discuss the potential mechanisms by which cells probe matrix stiffness and convert mechanical signals to regulate gene expression. We highlight the factors that govern matrix stiffness and outline the role of matrix stiffness in lung development and the pathogenesis of pulmonary fibrosis, pulmonary hypertension, asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. We envision targeting of deleterious matrix mechanical cues for treatment of fibrotic lung disease. Advances in technologies for matrix stiffness measurements and design of stiffness-tunable matrix substrates are also explored. © 2022 American Physiological Society. Compr Physiol 12:3523-3558, 2022.

Circ_0000705 facilitates proline metabolism of esophageal squamous cell carcinoma cells by targeting miR-621/PYCR1 axis

CircRNAs have been found to play crucial roles in the metabolism and progression of cancers, but their roles and mechanisms in esophageal squamous cell carcinoma (ESCC) have not been fully elucidated. This work is aimed to explore the role and mechanism of hsa_circ_0000705 (circ_0000705) in ESCC. Circ_0000705 expression was up-regulated in ESCC tissues and cell lines, and high circ_0000705 expression was correlated with poor survival. Circ_0000705 facilitated cell proliferation, invasion, migration and proline metabolism of ESCC cells. The inhibitory effects of circ_0000705 knockdown on cell invasion, migration and proline metabolism were partly rescued by miR-621 inhibition or PYCR1 over-expression. Furthermore, circ_0000705 expression is negatively correlated with miR-621 expression, and positively correlated with PYCR1 in ESCC tissues. Mechanistically, circ_0000705 acted as a ceRNA by sponging miR-621, thereby facilitating PYCR1 expression in ESCC cells. In conclusion, circ_0000705 promoted proline metabolism and malignant progression of ESCC by regulating the miR‑621/PYCR1 axis.

Plasma Metabolomic Signature of Early Abuse in Middle-Aged Women

OBJECTIVE

Metabolomic profiling may provide insights into biological mechanisms underlying the strong epidemiologic links observed between early abuse and cardiometabolic disorders in later life.

METHODS

We examined the associations between early abuse and midlife plasma metabolites in two nonoverlapping subsamples from the Nurses' Health Study II, comprising 803 (mean age = 40 years) and 211 women (mean age = 61 years). Liquid chromatography-tandem mass spectrometry assays were used to measure metabolomic profiles, with 283 metabolites consistently measured in both subsamples. Physical and sexual abuse before age 18 years was retrospectively assessed by validated questions integrating type/frequency of abuse. Analyses were conducted in each sample and pooled using meta-analysis, with multiple testing adjustment using the q value approach for controlling the positive false discovery rate.

RESULTS

After adjusting for age, race, menopausal status, body size at age 5 years, and childhood socioeconomic indicators, more severe early abuse was consistently associated with five metabolites at midlife (q value < 0.20 in both samples), including lower levels of serotonin and C38:3 phosphatidylethanolamine plasmalogen and higher levels of alanine, proline, and C40:6 phosphatidylethanolamine. Other metabolites potentially associated with early abuse (q value < 0.05 in the meta-analysis) included triglycerides, phosphatidylcholine plasmalogens, bile acids, tyrosine, glutamate, and cotinine. The association between early abuse and midlife metabolomic profiles was partly mediated by adulthood body mass index (32% mediated) and psychosocial distress (13%-26% mediated), but not by other life-style factors.

CONCLUSIONS

Early abuse was associated with distinct metabolomic profiles of multiple amino acids and lipids in middle-aged women. Body mass index and psychosocial factors in adulthood may be important intermediates for the observed association.

Cancer-associated fibroblasts require proline synthesis by PYCR1 for the deposition of pro-tumorigenic extracellular matrix

Elevated production of collagen-rich extracellular matrix is a hallmark of cancer-associated fibroblasts (CAFs) and a central driver of cancer aggressiveness. Here we find that proline, a highly abundant amino acid in collagen proteins, is newly synthesized from glutamine in CAFs to make tumour collagen in breast cancer xenografts. PYCR1 is a key enzyme for proline synthesis and highly expressed in the stroma of breast cancer patients and in CAFs. Reducing PYCR1 levels in CAFs is sufficient to reduce tumour collagen production, tumour growth and metastatic spread in vivo and cancer cell proliferation in vitro. Both collagen and glutamine-derived proline synthesis in CAFs are epigenetically upregulated by increased pyruvate dehydrogenase-derived acetyl-CoA levels. PYCR1 is a cancer cell vulnerability and potential target for therapy; therefore, our work provides evidence that targeting PYCR1 may have the additional benefit of halting the production of a pro-tumorigenic extracellular matrix. Our work unveils new roles for CAF metabolism to support pro-tumorigenic collagen production.

Kindlin-2 promotes Src-mediated tyrosine phosphorylation of androgen receptor and contributes to breast cancer progression

Androgen receptor (AR) signaling plays important roles in breast cancer progression. We show here that Kindlin-2, a focal adhesion protein, is critically involved in the promotion of AR signaling and breast cancer progression. Kindlin-2 physically associates with AR and Src through its two neighboring domains, namely F1 and F0 domains, resulting in formation of a Kindlin-2-AR-Src supramolecular complex and consequently facilitating Src-mediated AR Tyr-534 phosphorylation and signaling. Depletion of Kindlin-2 was sufficient to suppress Src-mediated AR Tyr-534 phosphorylation and signaling, resulting in diminished breast cancer cell proliferation and migration. Re-expression of wild-type Kindlin-2, but not AR-binding-defective or Src-binding-defective mutant forms of Kindlin-2, in Kindlin-2-deficient cells restored AR Tyr-534 phosphorylation, signaling, breast cancer cell proliferation and migration. Furthermore, re-introduction of phosphor-mimic mutant AR-Y534D, but not wild-type AR reversed Kindlin-2 deficiency-induced inhibition of AR signaling and breast cancer progression. Finally, using a genetic knockout strategy, we show that ablation of Kindlin-2 from mammary tumors in mouse significantly reduced AR Tyr-534 phosphorylation, breast tumor progression and metastasis in vivo. Our results suggest a critical role of Kindlin-2 in promoting breast cancer progression and shed light on the molecular mechanism through which it functions in this process.

The potential of fecal microbiota and amino acids to detect and monitor patients with adenoma

The risk of recurrent dysplastic colonic lesions is increased following polypectomy. Yield of endoscopic surveillance after adenoma removal is low, while interval colorectal cancers occur. To longitudinally assess the dynamics of fecal microbiota and amino acids in the presence of adenomatous lesions and after their endoscopic removal. In this longitudinal case-control study, patients collected fecal samples prior to bowel preparation before scheduled colonoscopy and 3 months after this intervention. Based on colonoscopy outcomes, patients with advanced adenomas and nonadvanced adenomas (0.5-1.0 cm) who underwent polypectomy during endoscopy (n = 19) were strictly matched on age, body-mass index, and smoking habits to controls without endoscopic abnormalities (n = 19). Microbial taxa were measured by 16S RNA sequencing, and amino acids (AA) were measured by high-performance liquid chromatography (HPLC). Adenoma patients were discriminated from controls based on AA and microbial composition. Levels of proline (p = .001), ornithine (p = .02) and serine (p = .02) were increased in adenoma patients compared to controls but decreased to resemble those of controls after adenoma removal. These AAs were combined as a potential adenoma-specific panel (AUC 0.79(0.64-0.94)). For bacterial taxa, differences between patients with adenomas and controls were found (Bifidobacterium spp.↓, Anaerostipes spp.↓, Butyricimonas spp.↑, Faecalitalea spp.↑ and Catenibacterium spp.↑), but no alterations in relative abundance were observed after polypectomy. Furthermore, Faecalitalea spp. and Butyricimonas spp. were significantly correlated with adenoma-specific amino acids. We selected an amino acid panel specifically increased in the presence of adenomas and a microbial signature present in adenoma patients, irrespective of polypectomy. Upon validation, these panels may improve the effectiveness of the surveillance program by detection of high-risk individuals and determination of surveillance endoscopy timing, leading to less unnecessary endoscopies and less interval cancer.

Kindlin-2 protects pancreatic β cells through inhibiting NLRP3 inflammasome activation in diabetic mice

Diabetes mellitus has been a major public health problem worldwide, characterized by insulin resistance and dysfunction of β-cells. A previous study showed that Kindlin-2 loss in β-cells dramatically reduces insulin secretion and decreases β-cell mass, resulting in severe diabetes-like phenotypes. It suggests that Kindlin-2 in β-cells play an important role in regulating glucose homeostasis. However, the effect of Kindlin-2 on the function of β-cells under chronic hyperglycemia in diabetes has not been explored. Here we report that Kindlin-2 overexpression ameliorates diabetes and improves insulin secretion in mice induced by streptozocin. In contrast, Kindlin-2 insufficiency exacerbates diabetes and promotes β-cells dysfunction and inflammation in β-cells induced by a high-fat diet (HFD). In vitro, Kindlin-2 overexpression prevented high-glucose (HG)-induced dysfunction in β-cells. Kindlin-2 overexpression also decreased the expression of pro-inflammatory cytokines and NLRP3 inflammasome expression in β-cells exposed to HG. Furthermore, the loss of Kindlin-2 aggravates the expression of inflammatory cytokines and NLRP3 induced by HG in β-cells. Collectively, we demonstrate that Kindlin-2 protects against diabetes by inhibiting NLRP3 inflammasome activation.

Kindlin-2 preserves integrity of the articular cartilage to protect against osteoarthritis

Osteoarthritis (OA) is an aging-related degenerative joint disease with a poorly defined mechanism. Here we report that kindlin-2 is highly expressed in articular chondrocytes and downregulated in the degenerated cartilage of aged mice and patients with OA. Kindlin-2 deletion in articular chondrocytes leads to spontaneous OA and exacerbates instability-induced OA lesions in adult mice. Kindlin-2 deficiency promotes mitochondrial oxidative stress and activates Stat3, leading to Runx2-mediated chondrocyte catabolism. Pharmacological inhibition of Stat3 activation or genetic ablation of Stat3 in chondrocytes reverses aberrant accumulation of Runx2 and extracellular-matrix-degrading enzymes and limits OA deteriorations caused by kindlin-2 deficiency. Deleting Runx2 in chondrocytes reverses structural changes and OA lesions caused by kindlin-2 deletion without downregulating p-Stat3. Intra-articular injection of AAV5-kindlin-2 decelerates progression of aging- and instability-induced knee joint OA in mice. Collectively, we identify a pathway consisting of kindlin-2, Stat3 and Runx2 in articular chondrocytes that is responsible for maintaining articular cartilage integrity and define a potential therapeutic target for OA.

Current Advances in 3D Bioprinting for Cancer Modeling and Personalized Medicine

Tumor cells evolve in a complex and heterogeneous environment composed of different cell types and an extracellular matrix. Current 2D culture methods are very limited in their ability to mimic the cancer cell environment. In recent years, various 3D models of cancer cells have been developed, notably in the form of spheroids/organoids, using scaffold or cancer-on-chip devices. However, these models have the disadvantage of not being able to precisely control the organization of multiple cell types in complex architecture and are sometimes not very reproducible in their production, and this is especially true for spheroids. Three-dimensional bioprinting can produce complex, multi-cellular, and reproducible constructs in which the matrix composition and rigidity can be adapted locally or globally to the tumor model studied. For these reasons, 3D bioprinting seems to be the technique of choice to mimic the tumor microenvironment in vivo as closely as possible. In this review, we discuss different 3D-bioprinting technologies, including bioinks and crosslinkers that can be used for in vitro cancer models and the techniques used to study cells grown in hydrogels; finally, we provide some applications of bioprinted cancer models.

The Interplay between Cell-Extracellular Matrix Interaction and Mitochondria Dynamics in Cancer

The tumor microenvironment, in particular the extracellular matrix (ECM), plays a pivotal role in controlling tumor initiation and progression. In particular, the interaction between cancer cells and the ECM promotes cancer cell growth and invasion, leading to the formation of distant metastasis. Alterations in cancer cell metabolism is a key hallmark of cancer, which is often associated with alterations in mitochondrial dynamics. Recent research highlighted that, changes in mitochondrial dynamics are associated with cancer migration and metastasis-these has been extensively reviewed elsewhere. However, less is known about the interplay between the extracellular matrix and mitochondria functions. In this review, we will highlight how ECM remodeling associated with tumorigenesis contribute to the regulation of mitochondrial function, ultimately promoting cancer cell metabolic plasticity, able to fuel cancer invasion and metastasis.

Kindlin-2 Mediates Lipopolysaccharide-Induced Acute Lung Injury Partially via Pyroptosis in Mice

Acute lung injury (ALI) is characteristic of the wholesale destruction of the lung endothelial barrier, which results in protein-rich lung edema, influx of pro-inflammatory leukocytes, and intractable hypoxemia, contributing to high mortality. Kindlin-2 is involved in the process of tumor- and wound healing-associated inflammation. However, the effects of kindlin-2 on lipopolysaccharide (LPS)-induced ALI and its mechanisms remain unknown. In this study, we found that the concentration of kindlin-2 was elevated in the lungs of ALI mice. The specific deletion of kindlin-2 by kindlin-2 siRNA attenuated the severity of lung injury, which was demonstrated by the reduced number of pro-inflammatory cells in bronchoalveolar lavage fluid and lung wet/dry weight ratio, and ameliorated pathologic changes in the lungs of ALI mice. Furthermore, kindlin-2 siRNA decreased the mRNA levels of pro-inflammatory factors (IL-1β, IL-6, and TNF-α) and the protein levels of pyroptosis-related proteins. In vitro studies confirmed that LPS + ATP promoted the expressions of pro-inflammatory factors and pyroptosis-related proteins, which was prevented by kindlin-2 siRNA pretreatment in endothelial cells (ECs). In conclusion, inhibition of kindlin-2 developes protective effects against LPS-induced ALI and the cytotoxicity of ECs, which may depend on blocking pyroptosis.

Increased mitochondrial proline metabolism sustains proliferation and survival of colorectal cancer cells

Research into the metabolism of the non-essential amino acid (NEAA) proline in cancer has gained traction in recent years. The last step in the proline biosynthesis pathway is catalyzed by pyrroline-5-carboxylate reductase (PYCR) enzymes. There are three PYCR enzymes: mitochondrial PYCR1 and 2 and cytosolic PYCR3 encoded by separate genes. The expression of the PYCR1 gene is increased in numerous malignancies and correlates with poor prognosis. PYCR1 expression sustains cancer cells' proliferation and survival and several mechanisms have been implicated to explain its oncogenic role. It has been suggested that the biosynthesis of proline is key to sustain protein synthesis, support mitochondrial function and nucleotide biosynthesis. However, the links between proline metabolism and cancer remain ill-defined and are likely to be tissue specific. Here we use a combination of human dataset, human tissue and mouse models to show that the expression levels of the proline biosynthesis enzymes are significantly increased during colorectal tumorigenesis. Functionally, the expression of mitochondrial PYCRs is necessary for cancer cells' survival and proliferation. However, the phenotypic consequences of PYCRs depletion could not be rescued by external supplementation with either proline or nucleotides. Overall, our data suggest that, despite the mechanisms underlying the role of proline metabolism in colorectal tumorigenesis remain elusive, targeting the proline biosynthesis pathway is a suitable approach for the development of novel anti-cancer therapies.