Src Activation Research Articles

Src-FAK Signaling Mediates Interleukin 6-Induced HCT116 Colorectal Cancer Epithelial–Mesenchymal Transition

Colorectal cancer is one of the most prevalent and lethal malignancies, affecting approximately 900,000 individuals each year worldwide. Patients with colorectal cancer are found with elevated serum interleukin-6 (IL-6), which is associated with advanced tumor grades and is related to their poor survival outcomes. Although IL-6 is recognized as a potent inducer of colorectal cancer progression, the detail mechanisms underlying IL-6-induced colorectal cancer epithelial-mesenchymal transition (EMT), one of the major process of tumor metastasis, remain unclear. In the present study, we investigated the regulatory role of IL-6 signaling in colorectal cancer EMT using HCT116 human colorectal cancer cells. We noted that the expression of epithelial marker E-cadherin was reduced in HCT116 cells exposed to IL-6, along with the increase in a set of mesenchymal cell markers including vimentin and α-smooth muscle actin (α-SMA), as well as EMT transcription regulators-twist, snail and slug. The changes of EMT phenotype were related to the activation of Src, FAK, ERK1/2, p38 mitogen-activated protein kinase (p38MAPK), as well as transcription factors STAT3, κB and C/EBPβ. IL-6 treatment has promoted the recruitment of STAT3, κB and C/EBPβ toward the Twist promoter region. Furthermore, the Src-FAK signaling blockade resulted in the decline of IL-6 induced activation of ERK1/2, p38MAPK, κB, C/EBPβ and STAT3, as well as the decreasing mesenchymal state of HCT116 cells. These results suggested that IL-6 activates the Src-FAK-ERK/p38MAPK signaling cascade to cause the EMT of colorectal cancer cells. Pharmacological approaches targeting Src-FAK signaling may provide potential therapeutic strategies for rescuing colorectal cancer progression.

Morphine-induced mechanical hypersensitivity in mice requires δ receptors, β-arrestin2, and c-Src activity.

Morphine diminishes pain, but its long-term use is compromised by tolerance and hyperalgesia. Studies implicate δ receptors, β-arrestin2 and Src kinase in tolerance. We examined whether these proteins are also involved in morphine-induced hypersensitivity (MIH). A common pathway for tolerance and hypersensitivity may provide a single target to guide improved analgesic approaches. We examined mechanical sensitivity using automated von Frey in wild-type (WT) and transgenic male and female C57Bl/6mice before and after hind paw inflammation by complete Freund's adjuvant (CFA). CFA-evoked hypersensitivity ceased on day 7 in WT but persisted for the 15-day testing period in μ-/- . Recovery was delayed until day 13 in δ-/- . We explored the expression of opioid genes in the spinal cord using quantitative RT-PCR. Restoration to basal sensitivity in WT occurred with increased δ expression. By contrast, κ expression was reduced, while μ remained unchanged. Daily morphine reduced hypersensitivity in WT on day 3 compared to controls; however, hypersensitivity recurred on day 9 and beyond. By contrast, WT had no recurrence of hypersensitivity in the absence of daily morphine. We used β-arrestin2-/- , δ-/- and Src inhibition by dasatinib in WT to establish whether these approaches, which diminish tolerance, also attenuate MIH. While none of these approaches affected CFA-evoked inflammation or acute hypersensitivity, all caused sustained morphine anti-hypersensitivity, abolishing MIH. Like morphine tolerance, MIH in this model requires δ receptors, β-arrestin2 and Src activity. Our findings suggest that MIH is caused by a tolerance-induced reduction in endogenous opioid signalling. KEY POINTS: Morphine is effective for treating severe acute pain, but tolerance and hypersensitivity often develop during its use in treating chronic pain. It is unclear whether these detrimental effects share similar mechanisms; if so, it might be possible to develop a single approach to minimise both phenomena. Mice deficient in μ receptors, δ receptors or β-arrestin2 and wild type mice treated with the Src inhibitor dasatinib exhibit negligible morphine tolerance. We show that these same approaches also prevent the development of morphine-induced hypersensitivity during persistent inflammation. This knowledge identifies strategies, such as the use of Src inhibitors, which may mitigate tolerance and morphine induced hyperalgesia.

A6 PROTEASE-ACTIVATED RECEPTOR (PAR)-2 ACTIVATION ENHANCES EPITHELIAL WOUND HEALING MIGRATION THROUGH SRC AND RAC1 PATHWAYS

Abstract Background Protease-activated receptors (PARs) and their activating enzymes have been postulated to play a role in inflammatory bowel disease (IBD) pathogenesis, but the specific roles of PAR2 in disease initiation and progression remain unclear. PAR2 activation has both pro-proliferative and pro-migratory effects and could be involved with the restoration of the epithelial barrier following injury. We previously showed that PAR2 activation increases epithelial wound healing through ERK, PI3K, and JNK pathways. However, the role of Src kinase and RhoGTPases, which PAR2 also activates, is not known. Purpose We hypothesized that PAR-2 activation induces wound healing in intestinal epithelial cells through Src and Rac1 activity. Method Circular wounds were made in T84 colonic epithelial cell monolayers. Wounded monolayers were treated with the PAR2 activating peptide, 2-furoyl-LIGRLO (2fLI, 5 μM), or the inactive control reverse-sequence peptide, 2-furoyl-OLRGIL (2fO, 5 μM), and live-cell imaging was used to record wound healing over a 24-hr period. Proliferation and apoptosis were measured using EdU and TUNEL assays, respectively. The mechanism of action was evaluated using inhibitors of Src (PP2), EGFR (PD153035), MLCK (ML-7), ROCK (Y-27632), Rac1 (NSC 23766), and Cdc42 (ML141), and western blot (WB) was used to confirm the protein levels of p-Src (Y416), p-ERK1/2, p-JNK, and p-PI3K. For immunofluorescence, images of E-cadherin and F-actin were taken to capture the entire wound border and surrounding cells. Result(s) PAR2 activation by 2fLI promoted wound healing compared to 2fO or vehicle control at the 24-hr time point (p<0.05). PAR2 activation had no effect on proliferation at the wound edge and did not affect apoptosis but did enhance lamellipodia/filopodia formation (p<0.001). These findings indicate that PAR2 reprograms the cells toward a migratory rather than a proliferative phenotype. When we investigated the mechanisms of action, the Src tyrosine kinase inhibitor, PP2, blocked PAR2-induced wound healing (p<0.0001). PAR2 activation increased Src phosphorylation (Y416, p<0.05) and the immunofluorescence showed a rise in actin cable formation at the wound edge and a reduction in lamellipodia/filopodia formation in the group treated with PP2 when compared to 2fLI (p<0.001). Although PAR2 activation increases the phosphorylation of ERK1/2 and JNK, this did not happen through Src. Furthermore, PAR2 did not increase the phosphorylation of PI3K as confirmed by WB analysis. Inhibition of EGFR (PD153035), MLCK (ML-7), ROCK (Y-27632), and Cdc42 (ML-141) did not alter PAR2-induced wound healing (p>0.05). In contrast, Rac1 inhibition by NSC23766 completely abrogated the PAR2-induced wound healing (p<0.05). Conclusion(s) PAR2 activation drives wound healing via Src tyrosine kinase and Rac1 activities. These findings provide a further mechanism whereby PAR2 can participate in the resolution of intestinal wounds in gastrointestinal inflammatory diseases. Disclosure of Interest None Declared

CU06-1004 alleviates vascular hyperpermeability in a murine model of hereditary angioedema by protecting the endothelium.

Over-release of the vasoactive peptide bradykinin (BK) due to mutation in the SERPING1 gene is the leading cause of hereditary angioedema (HAE). BK directly activates endothelial cells and increases vascular permeability by disrupting the endothelial barrier, leading to angioedema affecting face, lips, extremities, gastrointestinal tract, and larynx. Although various pharmacological treatment options for HAE became available during the last decade, they are presently limited and pose a major economic burden on patients. To identify additional therapeutic options for HAE, we evaluated the effect of CU06-1004, an endothelial dysfunction blocker, on BK-induced vascular hyperpermeability and the HAE murine model. To investigate the effect of CU06-1004 on BK-induced vascular hyperpermeability in vivo, we pre-administrated WT mice with the drug and then induced vascular leakage through intravenous injection of BK and observed vascular alternation. Then, SERPING1 deficient mice were used for a HAE murine model. For an in vitro model, the HUVEC monolayer was pre-treated with CU06-1004 and then stimulated with BK. Bradykinin disrupted the endothelial barrier and formed interendothelial cell gaps, leading to hyperpermeability in vivo and in vitro. However, CU06-1004 treatment protected the endothelial barrier by suppressing Src and myosin light chain activation via BK and alleviated hyperpermeability. Our study shows that CU06-1004 oral administration significantly reduced vascular hyperpermeability in the HAE murine model by protecting the endothelial barrier function against BK stimulation. Therefore, protecting endothelium against BK with CU06-1004 could serve as a potential prophylactic/therapeutic approach for HAE patients.

Chemokine (C-C motif) Ligand 2 Is Regulated Through the EGFR/Src Pathway in HER2-positive Breast Cancer Cells.

Chemokine (C-C motif) ligand 2 (CCL2) influences growth and metastasis and is associated with poor prognosis in various cancers. However, the regulatory mechanism of CCL2 induction by human epidermal growth factor receptor 2 (HER2) is not fully understood in breast cancer. Thus, we investigated how CCL2 expression is regulated in HER2-positive (HER2+) breast cancer. A human cytokine array was performed to investigate the differential expression of cytokines by HER2 overexpression. Quantitative reverse transcription PCR, enzyme-linked immunosorbent assay and western blot were performed to detect the levels of mRNA and protein expression. Cell cycle and proliferation were analyzed by flow cytometry. Cell invasion was analyzed by Boyden chamber assay. Our results showed that HER2 overexpression augmented CCL2 expression. Epidermal growth factor receptor (EGFR) and Src activities were increased in the HER2-overexpressed breast cancer cells. Interestingly, HER2-induced CCL2 expression could not be down-regulated by trastuzumab, while neratinib or saracatinib led to a decrease in the expression of CCL2 in HER2+ breast cancer cells. CCL2 expression is regulated through the EGFR/Src-dependent signaling in HER2+ breast cancer.

Glucose-mediated N-glycosylation of RPTPα affects its subcellular localization and Src activation.

Receptor-type protein tyrosine phosphatase α (RPTPα) is one of the typical PTPs that play indispensable roles in many cellular processes associated with cancers. It has been considered as the most powerful regulatory oncogene for Src activation, however it is unclear how its biological function is regulated by post-translational modifications. Here, we show that the extracellular segment of RPTPα is highly N-glycosylated precisely at N21, N36, N68, N80, N86, N104 and N124 sites. Such N-glycosylation modifications mediated by glucose concentration alter the subcellular localization of RPTPα from Golgi apparatus to plasma membrane, enhance the interaction of RPTPα with Src, which in turn enhances the activation of Src and ultimately promotes tumor development. Our results identified the N-glycosylation modifications of RPTPα, and linked it to glucose starvation and Src activation for promoting tumor development, which provides new evidence for the potential antitumor therapy.

Anti–Na+/K+-ATPase DR antibody attenuates UUO-induced renal fibrosis through inhibition of Na+/K+-ATPase α1–dependent HMGB1 release

Reduced Na+/K+-ATPase (NKA) activity and NKAα1 expression are engaged in the pathologies of renal diseases. NKA-mediated Src activation is not the only reason for NKA-related renal fibrosis. In this study, we found that genetic reduction of NKAα1 exhibited exacerbated tubulointerstitial lesions and fibrosis in the UUO mice model. Activation of NKAα1 with an antibody against the extracellular DR region of the NKAα1 subunit (DRm217) prevented UUO-induced tubulointerstitial lesions, preserved kidney function, and decrease renal fibrosis. Further studies revealed that NKAα1 deficiency mice exhibited high inflammation factors expression when they suffered UUO surgery, compared with NKAα1+/+ (WT) mice. DRm217 alleviated inflammatory cell infiltration, suppress NF-κB phosphorylation, and decreased inflammatory factors expression in the UUO mice model. Released HMGB1 can trigger the inflammatory response and contribute to renal fibrosis. Knockdown of NKA in renal tubular cells or in NKAα1+/- mice was associated with more susceptibility to HMGB1 release in the UUO mice model. DRm217 exerted its antifibrotic effect via inhibiting HMGB1 release. Furthermore, AMPK activation participates in the effect of DRm217 on inhibiting HMGB1 release. Our findings suggest that NKAα1 is a regulator of renal fibrosis and its DR-region is a novel target on it.

Src heterodimerically activates Lyn or Fyn to serve as targets for the diagnosis and treatment of esophageal squamous cell carcinoma.

Although Src is one of the oldest and most investigated oncoproteins, its function in tumor malignancy remains to be defined further. In this study, we demonstrated that the inhibition of Src activity by ponatinib effectively suppressed several malignant phenotypes of esophageal squamous cell carcinoma (ESCC) both in vitro and in vivo, whereas it did not produce growth-inhibitory effects on normal esophageal epithelial cells (NEECs). Importantly, we combined phosphoproteomics and several cellular and molecular biologic strategies to identify that Src interacted with the members of Src-family kinases (SFKs), such as Fyn or Lyn, to form heterodimers. Src interactions with Fyn and Lyn phosphorylated the tyrosine sites in SH2 (Fyn Tyr185 or Lyn Tyr183) and kinase domains (Fyn Tyr420 or Lyn Tyr397), which critically contributed to ESCC development. By contrast, Src could not form heterodimers with Fyn or Lyn in NEECs. We used RNA sequencing to comprehensively demonstrate that the inhibition of Src activity effectively blocked several critical tumor-promoting pathways, such as JAK/STAT, mTOR, stemness-related, and metabolism-related pathways. Results of the real-time polymerase chain reaction (RT-PCR) assay confirmed that Lyn and Fyn were critical effectors for the Src-mediated expression of tumor growth or metastasis-related molecules. Furthermore, results of the clinical ESCC samples showed that the hyperactivation of pSrc Tyr419, Fyn Tyr185 or Tyr420, and Lyn Tyr183 or Tyr397 could be biomarkers of ESCC prognosis. This study illustrates that Src/Fyn and Src/Lyn heterodimers serve as targets for the treatment of ESCC.

Dipeptidylpeptidase 4 promotes survival and stemness of acute myeloid leukemia stem cells.

Leukemic-stem-cell-specific targeting may improve the survival of patients with acute myeloid leukemia (AML) by avoiding the ablative effects of standard regimens on normal hematopoiesis. Herein, we perform an unbiased screening of compounds targeting cell surface proteins and identify clinically used DPP4 inhibitors as strong suppressors of AML development in both murine AML models and primary human AML cells xenograft model. We find in retrovirus-induced AML mouse models that DPP4-deficient AML cell-transplanted mice exhibit delay and reversal of AML development, whereas deletion of DPP4 has no significant effect on normal hematopoiesis. DPP4 activates and sustains survival of AML stem cells that are critical for AML development in both human and animal models via binding with Src kinase and activation of nuclear factor κB (NF-κB) signaling. Thus, inhibition of DPP4 is a potential therapeutic strategy against AML development through suppression of survival and stemness of AML cells.

Phillygenin Attenuated Colon Inflammation and Improved Intestinal Mucosal Barrier in DSS-induced Colitis Mice via TLR4/Src Mediated MAPK and NF-κB Signaling Pathways.

Ulcerative colitis (UC) is a chronic, relapsing, and nonspecific inflammatory bowel disease (IBD). Phillygenin (PHI), a natural bioactive ingredient, isolated from Forsythiae Fructus, exhibits anti-inflammatory, anti-oxidative, and hepatoprotective activities. However, few reports provide direct evidence on the efficacy of PHI in improving colitis mice. The present study elucidated that the symptoms of DSS-induced colitis mice were alleviated after PHI administration, including body weight loss, the disease activity index, colon length shortening, colonic pathological damage, splenomegaly, and hepatomegaly. PHI treatment improved the intestinal mucosal barrier by protecting goblet cells, promoting gene expressions of Clca1, Slc26a3, and Aqp8, increasing tight junction proteins (TJs), and reducing epithelial cell apoptosis. In addition, the levels of oxidative stress (MPO, SOD, and MDA) and inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-10) were reversed by PHI in colitis mice. According to transcriptome and network pharmacology analysis, inflammatory pathway might be an important mechanism for PHI to improve colitis. Western blotting displayed that the PHI inhibited the activation of tyrosine kinase Src mediated by TLR4, and then reduced the phosphorylation of downstream proteins p38, JNK, and NF-κB in colitis mice. In summary, our results suggested that PHI might be an appropriate and effective drug candidate to protect colitis.

Tyrosine kinase SRC-induced YAP1-KLF5 module regulates cancer stemness and metastasis in triple-negative breast cancer

SRC is the first identified oncogene, and its aberrant activation has been implicated as a driving event in tumor initiation and progression. However, its role in cancer stemness regulation and the underlying regulatory mechanism are still elusive. Here, we identified a YAP1 tyrosine phosphorylation-dependent YAP1-KLF5 oncogenic module, as the key downstream mediator of SRC kinase regulating cancer stemness and metastasis in triple-negative breast cancer (TNBC). SRC was overexpressed in TNBC patient tissues and its expression level was highly correlated with the tumor malignancy. SRC activation induced, while inhibition of SRC kinase reduced the cancer stemness, tumor cell growth and metastasis in vitro and in vivo. Transcriptomic and proteomic analysis revealed that SRC-mediated YAP1 tyrosine phosphorylation induced its interaction with Kruppel-like factor 5 (KLF5) to form a YAP1/TEAD-KLF5 complex in TNBC cells. YAP1-KLF5 association further promoted TEAD-mediated transcriptional program independently of canonical Hippo kinases, which eventually gave rise to the enhanced cancer stemness and metastasis. Disruption of YAP1-KLF5 module in TNBC cells dramatically attenuated the SRC-induced cancer stemness and metastasis in vitro and in vivo. Accordingly, co-upregulations of SRC and YAP1-KLF5 module in TNBC tissues were significantly positively correlated with the tumor malignance. Altogether, our work presents a novel tyrosine phosphorylation-dependent YAP1-KLF5 oncogenic module governing SRC-induced cancer stemness and metastasis in TNBC. Therefore, targeting YAP1/KLF5-mediated transcription may provide a promising strategy for TNBC treatment with SRC aberrantly activation.

Sesamin Attenuates VEGFA-Induced Angiogenesis via Inhibition of Src and FAK Signaling in Chick Chorioallantoic Membrane Model and Human Endothelial EA.hy926 Cells.

Sesamin, a major phytochemical in sesame seeds and oil, has been reported to have effects on physiological and pathological angiogenesis in several studies. Nevertheless, the underlying mechanisms of sesamin's effect on angiogenesis are not understood well enough. This study aimed to investigate its effect on both physiological and pathological angiogenesis using the in vivo chick chorioallantoic membrane (CAM) model and the in vitro human endothelial cell line, EA.hy926, model. Sesamin inhibited the VEGFA-induced pathological angiogenesis significantly, although no effect was seen on angiogenesis without induction. It reduced the formation of vascular branches in the VEGFA-treated CAMs and also the proliferation and migration of EA.hy926 endothelial cells induced by VEGFA. Sesamin impeded the VEGF-mediated activation of Src and FAK signaling proteins, which may be responsible for sesamin-mediated reduction of pathological angiogenesis. Moreover, the effect of sesamin on the expressions of angiogenesis-related genes was then investigated and it was found that both mRNA and protein expressions of Notch1, the key pathway in vascular development, induced by VEGFA, were significantly reduced by sesamin. Our results altogether suggested that sesamin, by inhibiting pathological angiogenesis, has the potential to be employed in the prevention or treatment of diseases with over-angiogenesis, such as cancers.

A Case of Dasatinib-Induced Keratosis Pilaris

Dasatinib is a second-generation tyrosine kinase inhibitor (TKI) indicated for treatment of chronic myeloid leukemia (CML). Dasatinib targets several proteins specific to cancer pathogenesis such as Bcr-Abl, Src, c-kit and PDGFRb. Cutaneous reactions are a well-documented side effect of many TKIs, however, there are limited reports and characterization of dasatinib induced rash. We report a case of keratosis pilaris and follicular epithelial thinning in a 19-year-old patient one month after beginning dasatinib for treatment of CML. This report suggests a possible role of dasatinib in the induction of epithelial follicular instability via reduced Src activity and subsequent down regulation of EGFR.

Inhibition of Oncogenic Src Ameliorates Silica-Induced Pulmonary Fibrosis via PI3K/AKT Pathway

Silicosis is a refractory disease. Previous studies indicate that damaged alveolar epithelial cells act as a driver in pulmonary fibrosis. Our results show that epithelial cells that acquire the mesenchymal phenotype are associated with the pathogenesis of silicosis. c-Src kinase, a non-receptor tyrosine kinase, has been shown to be a positive regulator of organ fibrosis, but specific mechanisms remain unclear and rarely researched in silicosis. The activated Phosphatidylinositol-3 kinases/AKT(PI3K/AKT) pathway promotes fibrosis. We aimed to determine whether c-Src regulates fibrosis via the PI3K/AKT signaling pathway in the development of silicosis. C57/BL mice were intratracheally perfused with 10 mg silica suspension to establish a model of silicosis. In vivo, silica particles induced lung fibrosis. The profibrotic cytokine transforming growth factor-β1 (TGF-β1) exhibited a high expression in pulmonary fibrosis. The phosphorylated c-Src protein was increased and the PI3K/AKT pathway was activated in model lung tissue. In vitro, silica increased the expression of TGF-β1- and TGF-β1-induced mesenchymal phenotype and fibrosis in a mouse epithelial cells line. siRNA-Src inhibited the c-Src, the phosphorylation of the PI3K/AKT pathway, and the mesenchymal phenotype induced by TGF-β1. LY294002, a specific inhibitor of PI3K, suppressed the phosphorylation of PI3K/AKT but did not affect Src activation. SU6656, a selective Src inhibitor, attenuated fibrosis in silicosis model. In summary, c-Src promotes fibrosis via the PI3K/AKT pathway in silica-induced lung fibrosis, and Src kinase inhibitors are potentially effective for silicosis treatment.

Endogenously Synthesized n-3 fatty Acids in fat-1 Transgenic Mice Suppresses B Cell Activation

n-3 Polyunsaturated fatty acids (PUFAs) have been suggested as a preventive or therapeutic strategy for autoimmune or inflammatory diseases via the modulation of the activation, differentiation, and effector functions of various immune cells, especially T cells and macrophages. Despite the importance of B cells in the pathogenesis of autoimmune diseases, few studies have demonstrated their effect on B cells. In this study, we investigated the possible effects of n-3 PUFAs on B cell activation, differentiation, and isotype switching in fat-1 transgenic mice, which can convert n-6 PUFAs to n-3 PUFAs via n-3 desaturase derived from Caenorhabditis elegans. Fat-1 mice were fed a corn oil-rich diet for at least 4 weeks to increase the probability of converting n-6 PUFAs to n-3 PUFAs. Splenic B cells were then isolated, followed by stimulation with Toll-like receptor 4 or B cell receptor (BCR). Our results showed that increased n-3 PUFA levels in B cells by fat-1 overexpression inhibited B cell proliferation, cytokine secretion, such as interleukin (IL)-6, IL-10, tumor necrosis factor-α, plasma cell differentiation, and Ig isotype switching/secretion. These effects are possibly due to the suppression of Syk, Src, and AKT activation in B cells from fat-1 mice, as well as NF-κB. Collectively, our results suggest that fat-1 expression attenuates B cell responses, and n-3 PUFA supplementation can be a possible strategy to treat pathological conditions in which B cells play a key role.

Identification of biological pathways and processes regulated by NEK5 in breast epithelial cells via an integrated proteomic approach

Specific members of the Nima-Related Kinase (NEK) family have been linked to cancer development and progression, and a role for NEK5, one of the least studied members, in breast cancer has recently been proposed. However, while NEK5 is known to regulate centrosome separation and mitotic spindle assembly, NEK5 signalling mechanisms and function in this malignancy require further characterization. To this end, we established a model system featuring overexpression of NEK5 in the immortalized breast epithelial cell line MCF-10A. MCF-10A cells overexpressing NEK5 exhibited an increase in clonogenicity under monolayer conditions and enhanced acinar size and abnormal morphology in 3D Matrigel culture. Interestingly, they also exhibited a marked reduction in Src activation and downstream signalling. To interrogate NEK5 signalling and function in an unbiased manner, we applied a variety of MS-based proteomic approaches. Determination of the NEK5 interactome by Bio-ID identified a variety of protein classes including the kinesins KIF2C and KIF22, the mitochondrial proteins TFAM, TFB2M and MFN2, RhoH effectors and the negative regulator of Src, CSK. Characterization of proteins and phosphosites modulated upon NEK5 overexpression by global MS-based (phospho)proteomic profiling revealed impact on the cell cycle, DNA synthesis and repair, Rho GTPase signalling, the microtubule cytoskeleton and hemidesmosome assembly. Overall, the study indicates that NEK5 impacts diverse pathways and processes in breast epithelial cells, and likely plays a multifaceted role in breast cancer development and progression.3vPKP8VT_3CNKdhee9few9Video

Hispolon Methyl Ether, a Hispolon Analog, Suppresses the SRC/STAT3/Survivin Signaling Axis to Induce Cytotoxicity in Human Urinary Bladder Transitional Carcinoma Cell Lines.

Bladder cancer is a leading human malignancy worldwide. Signal transducer and activator of transcription (STAT) 3 is an oncogenic transcription factor commonly hyperactivated in most human cancers, including bladder cancer. Notably, preclinical evidence has validated STAT3 blockade as a promising therapeutic strategy for bladder cancer. Hispolon Methyl Ether (HME) is a structural analog of hispolon, an anticancer component of the medicinal mushroom Phellinus linteus. Thus far, HME's anticancer activity and mechanisms remain largely unknown. We herein report HME was cytotoxic, more potent than cisplatin, and proapoptotic to various human bladder transitional carcinoma cell lines. Of note, HME blocked STAT3 activation, evidenced by HME-elicited reduction in tyrosine 705-phosphorylated STAT3 levels constitutively expressed or induced by interleukin-6. Significantly, HME-induced cytotoxicity was abrogated in cells expressing a dominant-active STAT3 mutant (STAT3-C), confirming STAT3 blockage as a pivotal mechanism of HME's cytotoxic action. We further revealed that survivin was downregulated by HME, while its levels were rescued in STAT3-C-expressing cells. Moreover, survivin overexpression abolished HME-induced cytotoxicity, illustrating survivin as a central downstream mediator of STAT3 targeted by HME. Lastly, HME was shown to lower tyrosine 416-phosphorylated SRC levels, suggesting that HME inhibits STAT3 by repressing the activation of SRC, a STAT3 upstream kinase. In conclusion, we present the first evidence of HME's anti-bladder cancer effect, likely proceeding by evoking apoptosis through suppression of the antiapoptotic SRC/STAT3/survivin signaling axis.

Src inhibitor dasatinib sensitized gastric cancer cells to cisplatin.

Gastric cancer (GC) is characterized by high incidence and mortality, and lacks effective treatment. Surgery, combined with chemo- and radiation therapy, represents the cornerstones of GC treatment. Although platinum is commonly used, severe side effects and drug resistance limited its application. Cisplatin-induced cell death mainly relies on the increment of reactive oxygen species (ROS), while the effect of dasatinib on ROS is inconclusive. In this article, dasatiniband cisplatin showed various anti-cancer properties on GC cells, which might be related to the changes of ROS levels. However, NAC enhanced cell death induced by dasatinib, although it elevated ROS levels in GES1 and AGS cells, suggesting that the elevation of ROS levels was not the responsible mechanism. Notably, dasatinib markedly synergized cells against cisplatin. Dasatinib decreased pSer473 Akt levels, and increased p53 expression, which was confirmed by LY294002 or Nutlin-3a co-treatment. Furthermore, transcriptome sequencing also confirmed that the PI3K/AKT pathway was involved in the anti-cancer effect of dasatinib or combined with cisplatin. Additionally, GC cells with higher Src activity (AGS) elicited more sensitive to dasatinib than lower cells (SGC7901 and MGC803), suggesting that the Src levels could be applied to pre-select patients who would benefit from dasatinib and/or combined with platinum compounds.

Suppressing of Src-Hic-5-JNK-AKT Signaling Reduced GAPDH Expression for Preventing the Progression of HuCCT1 Cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a malignant neoplasm of the bile ducts, being the second most common type of cancer in the liver, and most patients are diagnosed at a late stage with poor prognosis. Targeted therapy aiming at receptors tyrosine kinases (RTKs) such as c-Met or EGFR have been developed but with unsatisfactory outcomes. In our recent report, we found several oncogenic molecules downstream of RTKs, including hydrogen peroxide clone-5 (Hic-5), Src, AKT and JNK, were elevated in tissues of a significant portion of metastatic CCAs. By inhibitor studies and a knockdown approach, these molecules were found to be within the same signal cascade responsible for the migration of HuCCT1 cells, a conventionally used CCA cell line. Herein, we also found Src inhibitor dasatinib and Hic-5 siRNA corporately suppressed HuCCT1 cell invasion. Moreover, dasatinib inhibited the progression of the HuCCT1 tumor on SCID mice skin coupled with decreasing the expression of Hic-5 and EGFR and the activities of Src, AKT and JNK. In addition, we found a glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and several cytoskeletal molecules such as tubulin and cofilin were dramatically decreased after a long-term treatment of the HuCCT1 tumor with a high dose of dasatinib. Specifically, GAPDH was shown to be a downstream effector of the Hic-5/Src/AKT cascade involved in HuCCT1 cell migration. On the other hand, TFK1, another CCA cell line without Hic-5 expression, exhibited very low motility, whereas an ectopic Hic-5 expression enhanced the activation of Src and AKT and marginally increased TFK1 migration. In the future, it is tempting to investigate whether cotargeting Src, Hic-5 and/or GAPDH is efficient for preventing CCA progression in future clinical trials.

Caspase-8 as a novel mediator linking Src kinase signaling to enhanced glioblastoma malignancy.

Caspase-8 is a cysteine protease that plays an essential role in apoptosis. Consistently with its canonical proapoptotic function, cancer cells may genetically or epigenetically downregulate its expression. Unexpectedly, Caspase-8 is often retained in cancer, suggesting the presence of alternative mechanisms that may be exploited by cancer cells to their own benefit. In this regard, we reported that Src tyrosine kinase, which is aberrantly activated in many tumors, promotes Caspase-8 phosphorylation on Tyrosine 380 (Y380) preventing its full activation. Here, we investigated the significance of Caspase-8 expression and of its phosphorylation on Y380 in glioblastoma, a brain tumor where both Caspase-8 expression and Src activity are often aberrantly upregulated. Transcriptomic analyses identified inflammatory response as a major target of Caspase-8, and in particular, NFκB signaling as one of the most affected pathways. More importantly, we could show that Src-dependent phosphorylation of Caspase-8 on Y380 drives the assembly of a multiprotein complex that triggers NFκB activation, thereby inducing the expression of inflammatory and pro-angiogenic factors. Remarkably, phosphorylation on Y380 sustains neoangiogenesis and resistance to radiotherapy. In summary, our work identifies a novel interplay between Src kinase and Caspase-8 that allows cancer cells to hijack Caspase-8 to sustain tumor growth.