AMBRA1 levels predict resistance to MAPK inhibitors in melanoma.

Intrinsic and acquired resistance to mitogen-activated protein kinase inhibitors (MAPKi) in melanoma remains a major therapeutic challenge. Here, we show that the clinical development of resistance to MAPKi is associated with reduced tumor expression of the melanoma suppressor Autophagy and Beclin 1 Regulator 1 (AMBRA1) and that lower expression levels of AMBRA1 predict a poor response to MAPKi treatment. Functional analyses show that loss of AMBRA1 induces phenotype switching and orchestrates an extracellular signal-regulated kinase (ERK)-independent resistance mechanism by activating focal adhesion kinase 1 (FAK1). In both in vitro and in vivo settings, melanomas with low AMBRA1 expression exhibit intrinsic resistance to MAPKi therapy but higher sensitivity to FAK1 inhibition. Finally, we show that the rapid development of resistance in initially MAPKi-sensitive melanomas can be attributed to preexisting subclones characterized by low AMBRA1 expression and that cotreatment with MAPKi and FAK1 inhibitors (FAKi) effectively prevents the development of resistance in these tumors. In summary, our findings underscore the value of AMBRA1 expression for predicting melanoma response to MAPKi and supporting the therapeutic efficacy of FAKi to overcome MAPKi-induced resistance.

HMMR triggers immune evasion of hepatocellular carcinoma by inactivation of phagocyte killing.

Hepatocellular carcinoma (HCC) acquires an immunosuppressive microenvironment, leading to unbeneficial therapeutic outcomes. Hyaluronan-mediated motility receptor (HMMR) plays a crucial role in tumor progression. Here, we found that aberrant expression of HMMR could be a predictive biomarker for the immune suppressive microenvironment of HCC, but the mechanism remains unclear. We established an HMMR-/- liver cancer mouse model to elucidate the HMMR-mediated mechanism of the dysregulated "don't eat me" signal. HMMR knockout inhibited liver cancer growth and induced phagocytosis. HMMRhigh liver cancer cells escaped from phagocytosis via sustaining CD47 signaling. Patients with HMMRhighCD47high expression showed a worse prognosis than those with HMMRlowCD47low expression. HMMR formed a complex with FAK/SRC in the cytoplasm to activate NF-κB signaling, which could be independent of membrane interaction with CD44. Notably, targeting HMMR could enhance anti-PD-1 treatment efficiency by recruiting CD8+ T cells. Overall, our data revealed a regulatory mechanism of the "don't eat me" signal and knockdown of HMMR for enhancing anti-PD-1 treatment.

Cancer-associated fibroblast-derived periostin promotes papillary thyroid tumor growth through integrin-FAK-STAT3 signaling.

Background: Periostin (POSTN) is a critical extracellular matrix protein in various tumor microenvironments. However, the function of POSTN in thyroid cancer progression remains largely unknown. Methods: Postn and Rag1 knock-out mice and orthotopic mouse models were used to determine the role of POSTN on papillary thyroid tumor progression. Immunofluorescence, cell co-culture, fluorescence in situ hybridization, chromatin immunoprecipitation assay, recombinant protein and inhibitor treatment were performed to explore the underlying mechanisms of POSTN-promoted papillary thyroid tumor growth. Results: POSTN is up-regulated in papillary thyroid tumors and negatively correlates with the overall survival of patients with thyroid cancer. Cancer-associated fibroblast (CAF)-derived POSTN promotes papillary thyroid tumor growth in vivo and in vitro. POSTN deficiency in CAFs significantly impairs CAF-promoted papillary thyroid tumor growth. POSTN promotes papillary thyroid tumor cell proliferation and IL-4 expression through integrin-FAK-STAT3 signaling. In turn, tumor cell-derived IL-4 induces the activation of CAFs and stimulates POSTN expression by activating STAT6. We reveal the crucial role of CAF-derived POSTN and tumor cell-derived IL-4 in driving the development of papillary thyroid tumors through the POSTN-integrin-FAK-STAT3-IL-4 pathway in tumor cells and IL-4-STAT6-POSTN signaling in CAFs. Conclusion: Our findings underscore the significance of POSTN and IL-4 as critical molecular mediators in the dynamic interplay between CAFs and tumor cells, ultimately supporting the growth of papillary thyroid tumors.

CD276 enhances sunitinib resistance in clear cell renal cell carcinoma by promoting DNA damage repair and activation of FAK-MAPK signaling pathway.

OBJECTIVE: This study aimed to explore the effect of CD276 expression on the sunitinib sensitivity of clear cell renal cell carcinoma (ccRCC) cell and animal models and the potential mechanisms involved. METHODS: CD276 expression levels of ccRCC and normal samples were analyzed via online databases and real-time quantitative PCR (RT-qPCR). CD276 was knocked down in ccRCC cell models (sunitinib-resistant 786-O/R cells and sunitinib-sensitive 786-O cells) using shRNA transfection, and the cells were exposed to a sunitinib (2 µM) environment. Cells proliferation was then analyzed using MTT assay and colony formation experiment. Alkaline comet assay, immunofluorescent staining, and western blot experiments were conducted to assess the DNA damage repair ability of the cells. Western blot was also used to observe the activation of FAK-MAPK pathway within the cells. Finally, a nude mouse xenograft model was established and the nude mice were orally administered sunitinib (40 mg/kg/d) to evaluate the in vivo effects of CD276 knockdown on the therapeutic efficacy of sunitinib against ccRCC. RESULTS: CD276 was significantly upregulated in both ccRCC clinical tissue samples and cell models. In vitro experiments showed that knocking down CD276 reduced the survival rate, IC50 value, and colony-forming ability of ccRCC cells. Knocking down CD276 increased the comet tail moment (TM) values and γH2AX foci number, and reduced BRCA1 and RAD51 protein levels. Knocking down CD276 also decreased the levels of p-FAK, p-MEK, and p-ERK proteins. CONCLUSION: Knocking down CD276 effectively improved the sensitivity of ccRCC cell and animal models to sunitinib treatment.

Elucidating the Role of Let-7d-5p and OLR1 in the Progression and Prognosis of Oral Squamous Cell Carcinoma via FAK/P53 Signaling Axis.

BACKGROUND/AIM: Despite advances in oral squamous cell carcinoma (OSCC) diagnosis and treatment, the five-year survival rate remains low, underscoring the need for improved biomarkers and therapeutic strategies. This study investigated the role of let-7d-5p microRNA (miRNA) and its target gene OLR1 in OSCC, focusing on their implications in tumor progression, metastasis and potential as therapeutic targets. MATERIALS AND METHODS: Employing next-generation sequencing and bioinformatic tools, we profiled differentially expressed miRNAs in metastatic OSCC cell lines, identifying let-7d-5p as a key down-regulated miRNA and OLR1 as a novel target of let-7d-5p. We validated this interaction using luciferase reporter assays and studied the biological effects of modulating let-7d-5p and OLR1 expression on OSCC cell proliferation, migration, invasion, and stemness. Additionally, we analyzed clinical data to establish the relevance of OLR1 expression in OSCC prognosis. RESULTS: Our findings revealed let-7d-5p as a potent suppressor of OSCC metastasis, primarily by targeting and down-regulating OLR1. OLR1-silencing reduced OSCC cell invasiveness, migration, and stemness, indicating its prominent role in tumor progression. Mechanistically, let-7d-5p modulates a signaling cascade involving FAK, SRC, PAXILLIN, and p53, influencing cellular apoptosis and chemoresistance. Clinically, elevated OLR1 expression significantly correlates with advanced OSCC stages and poorer survival rates, highlighting its potential as a prognostic marker and therapeutic target. CONCLUSION: Our study uncovers the significance of the let-7d-5p-OLR1 axis in OSCC pathogenesis, offering novel insights for future therapeutic interventions.

FOXS1 acts as an oncogene and induces EMT through FAK/PI3K/AKT pathway by upregulating HILPDA in prostate cancer.

Prostate cancer (PCa) is a widespread global health concern characterized by elevated rates of occurrence, and there is a need for novel therapeutic targets to enhance patient outcomes. FOXS1 is closely linked to different cancers, but its function in PCa is still unknown. The expression of FOXS1, its prognostic role, clinical significance in PCa, and the potential mechanism by which FOXS1 affects PCa progression were investigated through bioinformatics analysis utilizing public data. The levels of FOXS1 and HILPDA were evaluated in clinical PCa samples using various methods, such as western blotting, immunohistochemistry, and qRT-PCR. To examine the function and molecular mechanisms of FOXS1 in PCa, a combination of experimental techniques including CCK-8 assay, flow cytometry, wound-healing assay, Transwell assay, and Co-IP assay were employed. The FOXS1 expression levels were significantly raised in PCa, correlating strongly with tumor aggressiveness and an unfavorable prognosis. Regulating FOXS1 expression, whether upregulating or downregulating it, correspondingly enhanced or inhibited the growth, migration, and invasion capabilities of PCa cells. Mechanistically, we detected a direct interaction between FOXS1 and HILPDA, resulting in the pathway activation of FAK/PI3K/AKT and facilitation EMT in PCa cells. FOXS1 collaborates with HILPDA to initiate EMT, thereby facilitating the PCa progression through the FAK/PI3K/AKT pathway activation.

Tumor microenvironment-induced FOXM1 regulates ovarian cancer stemness.

In ovarian tumors, the omental microenvironment profoundly influences the behavior of cancer cells and sustains the acquisition of stem-like traits, with major impacts on tumor aggressiveness and relapse. Here, we leverage a patient-derived platform of organotypic cultures to study the crosstalk between the tumor microenvironment and ovarian cancer stem cells. We discovered that the pro-tumorigenic transcription factor FOXM1 is specifically induced by the microenvironment in ovarian cancer stem cells, through activation of FAK/YAP signaling. The microenvironment-induced FOXM1 sustains stemness, and its inactivation reduces cancer stem cells survival in the omental niche and enhances their response to the PARP inhibitor Olaparib. By unveiling the novel role of FOXM1 in ovarian cancer stemness, our findings highlight patient-derived organotypic co-cultures as a powerful tool to capture clinically relevant mechanisms of the microenvironment/cancer stem cells crosstalk, contributing to the identification of tumor vulnerabilities.

Muscone restores anoikis sensitivity in TMZ-resistant glioblastoma cells by suppressing TOP2A via the EGFR/Integrin ß1/FAK signaling pathway.

BACKGROUND: Temozolomide (TMZ) resistance is the main obstacle faced by glioblastoma multiforme (GBM) treatment. Muscone, one of the primary active pharmacological ingredients of Shexiang (Moschus), can cross the blood-brain barrier (BBB) and is being investigated as an antineoplastic medication. However, muscone treatment for GBM has received little research, and its possible mechanisms are still unclear. PURPOSE: This study aims to evaluate the effect and the potential molecular mechanism of muscone on TMZ-resistant GBM cells. METHODS: The differentially expressed genes (DEGs) between TMZ-resistant GBM cells and TMZ-sensitive GBM cells were screened using GEO2R. By progressively raising the TMZ concentration, a relatively stable TMZ-resistant human GBM cell line was established. The drug-resistance traits of U251-TR cells were assessed via the CCK-8 assay and Western Blot analysis of MGMT and TOP2A expression. Cell viability, cell proliferation, cell migration ability, and drug synergism were detected by the CCK-8 assay, colony formation assay, wound healing assay, and drug interaction relationship test, respectively. Anoikis was quantified by Calcein-AM/EthD-1 staining, MTT assay, and flow cytometry. Measurements of cell cycle arrest, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were performed using cell cycle staining, Annexin V-FITC/PI labeling, JC-1 assay, and ROS assay, respectively. DNA damage was measured by TUNEL assay, alkaline comet assay, and γ-H2AX foci assay. GEPIA was used to investigate the link between the anoikis marker (FAK)/drug resistance gene and critical proteins in the EGFR/Integrin ß1 signaling pathway. Molecular docking was used to anticipate the probable targets of muscone. The intracellular co-localization and expression of EGFR and FAK were shown using immunofluorescence. The U251-TR cell line stably overexpressing EGFR was constructed using lentiviral transduction to assess the involvement of EGFR-related signaling in anoikis resistance. Western Blot was employed to detect the expression of migration-related proteins, cyclins, anoikis-related proteins, DNA damage/repair-related proteins, and associated pathway proteins. RESULTS: DEGs analysis identified 97 deregulated chemotherapy-resistant genes and 3779 upregulated genes in TMZ-resistant GBM cells. Subsequent experiments verified TMZ resistance and the hyper-expression of DNA repair-related genes (TOP2A and MGMT) in continuously low-dose TMZ-induced U251-TR cells. Muscone exhibited dose-dependent inhibition of U251-TR cell migration and proliferation, and its co-administration with TMZ showed the potential for enhanced therapeutic efficacy. By downregulating FAK, muscone reduced anoikis resistance in anchorage-independent U251-TR cells. It also caused cell cycle arrest in the G2/M phase by upregulating p21 and downregulating CDK1, CDK2, and Cyclin E1. Muscone-induced anoikis was accompanied by mitochondrial membrane potential collapse, ROS production, an increase in the BAX/Bcl-2 ratio, as well as elevated levels of Cytochrome c (Cyt c), cleaved caspase-9, and cleaved caspase-3. These findings indicated that muscone might trigger mitochondrial-dependent anoikis via ROS generation. Moreover, significant DNA damage, DNA double-strand breaks (DSBs), the formation of γ-H2AX foci, and a reduction in TOP2A expression are also associated with muscone-induced anoikis. Overexpression of EGFR in U251-TR cells boosted the expression of Integrin ß1, FAK, ß-Catenin, and TOP2A, whereas muscone suppressed the expression levels of EGFR, Integrin ß1, ß-Catenin, FAK, and TOP2A. Muscone may influence the expression of the key DNA repair enzyme, TOP2A, by suppressing the EGFR/Integrin ß1/FAK pathway. CONCLUSION: We first demonstrated that muscone suppressed TOP2A expression through the EGFR/Integrin ß1/FAK pathway, hence restoring anoikis sensitivity in TMZ-resistant GBM cells. These data suggest that muscone may be a promising co-therapeutic agent for enhancing GBM treatment, particularly in cases of TMZ-resistant GBM with elevated TOP2A expression.

Low concentrations of saracatinib promote definitive endoderm differentiation through inhibition of FAK-YAP signaling axis.

Optimizing the efficiency of definitive endoderm (DE) differentiation is necessary for the generation of diverse organ-like structures. In this study, we used the small molecule inhibitor saracatinib (SAR) to enhance DE differentiation of human embryonic stem cells and induced pluripotent stem cells. SAR significantly improved DE differentiation efficiency at low concentrations. The interaction between SAR and Focal Adhesion Kinase (FAK) was explored through RNA-seq and molecular docking simulations, which further supported the inhibition of DE differentiation by p-FAK overexpression in SAR-treated cells. In addition, we found that SAR inhibited the nuclear translocation of Yes-associated protein (YAP), a downstream effector of FAK, which promoted DE differentiation. Moreover, the addition of SAR enabled a significant reduction in activin A (AA) from 50 to 10 ng/mL without compromising DE differentiation efficiency. For induction of the pancreatic lineage, 10 ng/ml AA combined with SAR at the DE differentiation stage yielded a comparative number of PDX1+/NKX6.1+ pancreatic progenitor cells to those obtained by 50 ng/ml AA treatment. Our study highlights SAR as a potential modulator that facilitates the cost-effective generation of DE cells and provides insight into the orchestration of cell fate determination.

Focal adhesion kinase-YAP signaling axis drives drug-tolerant persister cells and residual disease in lung cancer.

Targeted therapy is effective in many tumor types including lung cancer, the leading cause of cancer mortality. Paradigm defining examples are targeted therapies directed against non-small cell lung cancer (NSCLC) subtypes with oncogenic alterations in EGFR, ALK and KRAS. The success of targeted therapy is limited by drug-tolerant persister cells (DTPs) which withstand and adapt to treatment and comprise the residual disease state that is typical during treatment with clinical targeted therapies. Here, we integrate studies in patient-derived and immunocompetent lung cancer models and clinical specimens obtained from patients on targeted therapy to uncover a focal adhesion kinase (FAK)-YAP signaling axis that promotes residual disease during oncogenic EGFR-, ALK-, and KRAS-targeted therapies. FAK-YAP signaling inhibition combined with the primary targeted therapy suppressed residual drug-tolerant cells and enhanced tumor responses. This study unveils a FAK-YAP signaling module that promotes residual disease in lung cancer and mechanism-based therapeutic strategies to improve tumor response.

The dysadherin/FAK axis promotes individual cell migration in colon cancer.

Dysregulation of cancer cell motility is a key driver of invasion and metastasis. High dysadherin expression in cancer cells is correlated with invasion and metastasis. Here, we found the molecular mechanism by which dysadherin regulates the migration and invasion of colon cancer (CC). Comprehensive analysis using single-cell RNA sequencing data from CC patients revealed that high dysadherin expression in cells is linked to cell migration-related gene signatures. We confirmed that the deletion of dysadherin in tumor cells hindered local invasion and distant migration using in vivo tumor models. In this context, by performing cell morphological analysis, we found that aberrant cell migration resulted from impaired actin dynamics, focal adhesion turnover and protrusive structure formation upon dysadherin expression. Mechanistically, the activation of focal adhesion kinase (FAK) was observed in dysadherin-enriched cells. The dysadherin/FAK axis enhanced cell migration and invasion by activating the FAK downstream cascade, which includes the Rho family of small GTPases. Overall, this study illuminates the role of dysadherin in modulating cancer cell migration by forcing actin dynamics and protrusive structure formation via FAK signaling, indicating that targeting dysadherin may be a potential therapeutic strategy for CC patients.

Biological evaluation of sulfonate and sulfate analogues of lithocholic acid: A bioisosterism-guided approach towards the discovery of potential sialyltransferase inhibitors for antimetastatic study.

The naturally occurring bile acid lithocholic acid (LCA) has been a crucial core structure for many non-sugar-containing sialyltranferase (ST) inhibitors documented in literature. With the aim of elucidating the impact of the terminal carboxyl acid substituent of LCA on its ST inhibition, in this present study, we report the (bio)isosteric replacement-based design and synthesis of sulfonate and sulfate analogues of LCA. Among these compounds, the sulfate analogue SPP-002 was found to selectively inhibit N-glycan sialylation by at least an order of magnitude, indicating a substantial improvement in both potency and selectivity when compared to the unmodified parent bile acid. Molecular docking analysis supported the stronger binding of the synthetic analogue in the enzyme active site. Treatment with SPP-002 also hampered the migration, adhesion, and invasion of MDA-MB-231 cells in vitro by suppressing the expression of signaling proteins involved in the cancer metastasis-associated integrin/FAK/paxillin pathway. In totality, these findings offer not only a novel structural scaffold but also valuable insights for the future development of more potent and selective ST inhibitors with potential therapeutic effects against tumor cancer metastasis.

Effect of Focal Adhesion Kinase and Vinculin Expression on Migration Parameters of Normal and Tumor Epitheliocytes.

Focal adhesions (FAs) are mechanosensory structures that transform physical stimuli into chemical signals guiding cell migration. Comprehensive studies postulate correlation between the FA parameters and cell motility metrics for individual migrating cells. However, which properties of the FAs are critical for epithelial cell motility in a monolayer remains poorly elucidated. We used high-throughput microscopy to describe relationship between the FA parameters and cell migration in immortalized epithelial keratinocytes (HaCaT) and lung carcinoma cells (A549) with depleted or inhibited vinculin and focal adhesion kinase (FAK) FA proteins. To evaluate relationship between the FA morphology and cell migration, we used substrates with varying stiffness in the model of wound healing. Cells cultivated on fibronectin had the highest FA area values, migration rate, and upregulated expression of FAK and vinculin mRNAs, while the smallest FA area and slower migration rate to the wound were specific to cells cultivated on glass. Suppression of vinculin expression in both normal and tumor cells caused decrease of the FA size and fluorescence intensity but did not affect cell migration into the wound. In contrast, downregulation or inactivation of FAK did not affect the FA size but significantly slowed down the wound closure rate by both HaCaT and A549 cell lines. We also showed that the FAK knockdown results in the FA lifetime decrease for the cells cultivated both on glass and fibronectin. Our data indicate that the FA lifetime is the most important parameter defining migration of epithelial cells in a monolayer. The observed change in the cell migration rate in a monolayer caused by changes in expression/activation of FAK kinase makes FAK a promising target for anticancer therapy of lung carcinoma.

The c-Abl-RACK1-FAK signaling axis promotes renal fibrosis in mice through regulating fibroblast-myofibroblast transition.

BACKGROUND: Renal fibrosis is a prevalent manifestation of chronic kidney disease (CKD), and effective treatments for this disease are currently lacking. Myofibroblasts, which originate from interstitial fibroblasts, aggregate in the renal interstitium, leading to significant accumulation of extracellular matrix and impairment of renal function. The nonreceptor tyrosine kinase c-Abl (encoded by the Abl1 gene) has been implicated in the development of renal fibrosis. However, the precise role of c-Abl in this process and its involvement in fibroblast-myofibroblast transition (FMT) remain poorly understood. METHODS: To investigate the effect of c-Abl in FMT during renal fibrosis, we investigated the expression of c-Abl in fibrotic renal tissues of patients with CKD and mouse models. We studied the phenotypic changes in fibroblast or myofibroblast-specific c-Abl conditional knockout mice. We explored the potential targets of c-Abl in NRK-49F fibroblasts. RESULTS: In this study, fibrotic mouse and cell models demonstrated that c-Abl deficiency in fibroblasts mitigated fibrosis by suppressing fibroblast activation, fibroblast-myofibroblast transition, and extracellular matrix deposition. Mechanistically, c-Abl maintains the stability of the RACK1 protein, which serves as a scaffold for proteins such as c-Abl and focal adhesion kinase at focal adhesions, driving fibroblast activation and differentiation during renal fibrosis. Moreover, specifically targeting c-Abl deletion in renal myofibroblasts could prove beneficial in established kidney fibrosis by reducing RACK1 expression and diminishing the extent of fibrosis. CONCLUSIONS: Our findings suggest that c-Abl plays a pathogenic role in interstitial fibrosis through the regulation of RACK1 protein stabilization and myofibroblast differentiation, suggesting a promising strategy for the treatment of CKD.

LAMC1 attenuates neuronal apoptosis via FAK/PI3K/AKT signaling pathway after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: The poor prognosis in patients with subarachnoid hemorrhage (SAH) is often attributed to neuronal apoptosis. Recent evidence suggests that Laminin subunit gamma 1 (LAMC1) is essential for cell survival and proliferation. However, the effects of LAMC1 on early brain injury after SAH and the underlying mechanisms are unknown. The current study aimed to reveal the anti-neuronal apoptotic effect and the potential mechanism of LAMC1 in the rat and in the in vitro SAH models. METHODS: The SAH model of Sprague-Dawley rats was established by endovascular perforation. Recombinant LAMC1 (rLAMC1) was administered intranasally 30 min after modeling. LAMC1 small interfering RNA (LAMC1 siRNA), focal adhesion kinase (FAK)-specific inhibitor Y15 and PI3K-specific inhibitor LY294002 were administered before SAH modeling to explore the neuroprotection mechanism of rLAMC1. HT22 cells were cultured and stimulated by oxyhemoglobin to establish an in vitro model of SAH. Subsequently, SAH grades, neurobehavioral tests, brain water content, blood-brain barrier permeability, western blotting, immunofluorescence, TUNEL, and Fluoro-Jade C staining were performed. RESULTS: The expression of endogenous LAMC1 was markedly decreased after SAH, both in vitro and in vivo. rLAMC1 significantly reduced the brain water content and blood-brain barrier permeability, improved short- and long-term neurobehavior, and decreased neuronal apoptosis. Furthermore, rLAMC1 treatment significantly increased the expression of p-FAK, p-PI3K, p-AKT, Bcl-XL, and Bcl-2 and decreased the expression of Bax and cleaved caspase -3. Conversely, knockdown of endogenous LAMC1 aggravated the neurological impairment, suppressed the expression of Bcl-XL and Bcl-2, and upregulated the expression of Bax and cleaved caspase-3. Additionally, the administration of Y15 and LY294002 abolished the protective roles of rLAMC1. In vitro, rLAMC1 significantly reduced neuronal apoptosis, and the protective effects were also abolished by Y15 and LY294002. CONCLUSION: Exogenous LAMC1 treatment improved neurological deficits after SAH in rats, and attenuated neuronal apoptosis in both in vitro and in vivo SAH models, at least partially through the FAK/PI3K/AKT pathway.

Direct contact between tumor cells and platelets initiates a FAK-dependent F3/TGF-ß positive feedback loop that promotes tumor progression and EMT in osteosarcoma.

Platelets have received growing attention for their roles in hematogenous tumor metastasis. However, the tumor-platelet interaction in osteosarcoma (OS) remains poorly understood. Here, using platelet-specific focal adhesion kinase (FAK)-deficient mice, we uncover a FAK-dependent F3/TGF-ß positive feedback loop in OS. Disruption of the feedback loop by inhibition of F3, TGF-ß, or FAK significantly suppresses OS progression. We demonstrate that OS F3 initiated the feedback loop by increasing platelet TGF-ß secretion, and platelet-derived TGF-ß promoted OS F3 expression in turn and modulated OS EMT process. Immunofluorescence results indicate platelet infiltration in OS niche and we verified it was mediated by platelet FAK. In addition, platelet FAK was proved to mediate platelet adhesion to OS cells, which was vital for the initiation of F3/TGF-ß feedback loop. Collectively, these findings provide a rationale for novel therapeutic strategies targeting tumor-platelet interplay in metastatic OS.

FAK-LINC01089 negative regulatory loop controls chemoresistance and progression of small cell lung cancer.

The focal adhesion kinase (FAK) tyrosine kinase is activated and upregulated in multiple cancer types including small cell lung cancer (SCLC). However, FAK inhibitors have shown limited efficacy in clinical trials for cancer treatment. With the aim of identifying potential therapeutic strategies to inhibit FAK for cancer treatment, we investigated long non-coding RNAs (lncRNAs) that potentially regulate FAK in SCLC. In this study, we identified a long non-coding RNA LINC01089 that binds and inhibits FAK phosphorylation (activation). Expression analysis revealed that LINC01089 was downregulated in SCLC tissues and negatively correlated with chemoresistance and survival in SCLC patients. Functionally, LINC01089 inhibited chemoresistance and progression of SCLC in vitro and in vivo. Mechanistically, LINC01089 inhibits FAK activation by blocking binding with Src and talin kinases, while FAK negatively regulates LINC01089 transcription by activating the ERK signaling pathway to recruit the REST transcription factor. Furthermore, LINC01089-FAK axis mediates the expression of drug resist-related genes by modulating YBX1 phosphorylation, leading to drug resistance in SCLC. Intriguingly, the FAK-LINC01089 interaction depends on the co-occurrence of the novel FAK variant and the non-conserved region of LINC01089 in primates. In Conclusion, our results indicated that LINC01089 may serve as a novel high-efficiency FAK inhibitor and the FAK-LINC01089 axis represents a valuable prognostic biomarker and potential therapeutic target in SCLC.

A new invertebrate NPY-like polypeptide, ZoaNPY, from the Zoanthus sociatus, as a novel ligand of human NPY Y2 receptor rescues vascular insufficiency via PLC/PKC and Src- FAK-dependent signaling pathways.

Our recent multi-omics studies have revealed rich sources of novel bioactive proteins and polypeptides from marine organisms including cnidarians. In the present study, we initially conducted a transcriptomic analysis to review the composition profile of polypeptides from Zoanthus sociatus. Then, a newly discovered NPY-like polypeptide-ZoaNPY was selected for further in silico structural, binding and virtually pharmacological studies. To evaluate the pro-angiogenic effects of ZoaNPY, we employed an in vitro HUVECs model and an in vivo zebrafish model. Our results indicate that ZoaNPY, at 1-100 pmol, enhances cell survival, migration and tube formation in the endothelial cells. Besides, treatment with ZoaNPY could restore a chemically-induced vascular insufficiency in zebrafish embryos. Western blot results demonstrated the application of ZoaNPY could increase the phosphorylation of proteins related to angiogenesis signaling including PKC, PLC, FAK, Src, Akt, mTOR, MEK, and ERK1/2. Furthermore, through molecular docking and surface plasmon resonance (SPR) verification, ZoaNPY was shown to directly and physically interact with NPY Y2 receptor. In view of this, all evidence showed that the pro-angiogenic effects of ZoaNPY involve the activation of NPY Y2 receptor, thereby activating the Akt/mTOR, PLC/PKC, ERK/MEK and Src- FAK-dependent signaling pathways. Furthermore, in an excision wound model, the treatment with ZoaNPY was shown to accelerate the wound healing process in mice. Our findings provide new insights into the discovery and development of novel pro-angiogenic drugs derived from NPY-like polypeptides in the future.

Stromal Rigidity Stress Accelerates Pancreatic Intraepithelial Neoplasia Progression and Chromosomal Instability via Nuclear Protein Tyrosine Kinase 2 Localization.

Because the mechanotransduction by stromal stiffness stimulates the rupture and repair of the nuclear envelope in pancreatic progenitor cells, accumulated genomic aberrations are under selection in the tumor microenvironment. Analysis of cell growth, micronuclei, and phosphorylated Ser-139 residue of the histone variant H2AX (γH2AX) foci linked to mechanotransduction pressure in vivo during serial orthotopic passages of mouse KrasLSL-G12D/+;Trp53flox/flox;Pdx1-Cre (KPC) cancer cells in the tumor and in migrating through the size-restricted 3-µm micropores. To search for pancreatic cancer cell-of-origin, analysis of single-cell data sets revealed that the extracellular matrix shaped an alternate route of acinar-ductal transdifferentiation of acinar cells into topoisomerase II α (TOP2A)-overexpressing cancer cells and derived subclusters with copy number amplifications in MYC-PTK2 (protein tyrosine kinase 2) locus and PIK3CA. High-PTK2 expression is associated with 171 differentially methylated CpG loci, 319 differentially expressed genes, and poor overall survival in The Cancer Genome Atlas-Pancreatic Adenocarcinoma cohort. Abolished RGD-integrin signaling by disintegrin KG blocked the PTK2 phosphorylation, increased cancer apoptosis, decreased vav guanine nucleotide exchange factor 1 (VAV1) expression, and prolonged overall survival in the KPC mice. Reduction of α-smooth muscle actin deposition in the CD248 knockout KPC mice remodeled the tissue stroma and down-regulated TOP2A expression in the epithelium. In summary, stromal stiffness induced the onset of cancer cells-of-origin by ectopic TOP2A expression, and the genomic amplification of MYC-PTK2 locus via alternative transdifferentiation of pancreatic progenitor cells is the vulnerability useful for disintegrin KG treatment.

FAK mediates hypoxia-induced pulmonary artery smooth muscle cell proliferation by modulating mitochondrial transcription termination factor 1/cyclin D1.

This study aimed to investigate the mechanism of FAK-dependent hypoxia-induced proliferation on human pulmonary artery smooth muscle cells (HPASMCs). Primary HPASMCs were isolated and cultured in vitro under normal and hypoxia conditions to assess cell proliferation with cell counting kit-8. FAK and mitochondrial transcription termination factor 1 (mTERF1) were silenced with siRNA, mRNA, and protein levels of FAK, mTERF1, and cyclin D1 were determined. HPASMC proliferation increased under hypoxia compared to normal conditions. Knocking down FAK or mTERF1 with siRNA led to decreased cell proliferation under both normal and hypoxia conditions. FAK knockdown led to the reduction of both mTERF1 and cyclin D1 expressions under the hypoxia conditions, whereas mTERF1 knockdown led to the downregulation of cyclin D1 expression but not FAK expression under the same condition. However, under normal conditions, knocking down either FAK or mTERF1 had no impact on cyclin D1 expression. These results suggested that FAK may regulate the mTERF1/cyclin D1 signaling pathway to modulate cell proliferation in hypoxia.