AKT2^(S128)/CCTα^(S315/319/323)-positive cancer-associated fibroblasts (CAFs) mediate focal adhesion kinase (FAK) inhibitors resistance via secreting phosphatidylcholines (PCs)

Abnormal metabolism is regarded as an oncogenic hallmark related to tumor progression and therapeutic resistance.Present study employed multi-omics,including phosphoproteomics,untargeted metabolomics and lipidomics,to demonstrate that the pAKT2 Ser128 and pCCTαSer315/319/323-positive cancer-associated fibroblasts(CAFs)substantially release phosphatidylcholines(PCs),contributing to the resistance of focal adhesion kinase(FAK)inhibitors in esophageal squamous cell carcinoma(ESCC)treatment.Additionally,we observed extremely low levels of FAK Tyr397 expression in CAFs,potentially offering no available target for FAK inhibitors playing their anti-growth role in CAFs.Consequently,FAK inhibitor increased the intracellular concentration of Ca2+in CAFs,promoting the formation of AKT2/CCTαcomplex,leading to phosphorylation of CCTαSer315/319/323 sites and eventually enhancing stromal PC production.This activation could stimulate the intratumoral Janus kinase 2(JAK2)/Signal transducer and activator of transcription 3(STAT3)pathway,triggering resistance to FAK inhibition.Analysis of clinical samples demonstrated that stromal pAKT2 Ser128 and pCCTαSer315/319/323 are related to the tumor malignancy and reduced patient survival.Pseudo-targeted lipidomics and further validation cohort quantitatively showed that plasma PCs enable to distinguish the malignant extent of ESCC patients.In conclusion,inhibition of stroma-derived PCs and related pathway could be possible therapeutic strategies for tumor therapy.

PAFR/Stat3 axis maintains the symbiotic ecosystem between tumor and stroma to facilitate tumor malignancy

Stroma surrounding the tumor cells plays crucial roles for tumor progression.However,little is known about the factors that maintain the symbiosis between stroma and tumor cells.In this study,we found that the transcriptional regulator-signal transducer and activator of transcription 3(Stat3)was frequently activated in cancer-associated fibroblasts(CAFs),which was a potent facilitator of tumor malignancy,and formed forward feedback loop with platelet-activating factor receptor(PAFR)both in CAFs and tumor cells.Importantly,PAFR/Stat3 axis connected intercellular signaling crosstalk between CAFs and cancer cells and drove mutual transcriptional programming of these two types of cells.Two central Stat3-related cytokine signaling molecules-interleukin 6(IL-6)and IL-11 played the critical role in the process of PAFR/Stat3 axis-mediated communication between tumor and CAFs.Pharmacological inhibition of PAFR and Stat3 activities effectively reduced tumor progression using CAFs/tumor co-culture xenograft model.Our study reveals that PAFR/Stat3 axis enhances the interaction between tumor and its associated stroma and suggests that targeting this axis can be an effective therapeutic strategy against tumor malignancy.

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 growthinhibitory 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 Tyr^(185)or Lyn Tyr^(183))and kinase domains(Fyn Tyr^(420) or Lyn Tyr^(397)),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 Tyr^(419),Fyn Tyr^(185) or Tyr^(420),and Lyn Tyr^(183)or Tyr^(397)could be biomarkers of ESCC prognosis.This study illustrates that Src/Fyn and Src/Lyn heterodimers serve as targets for the treatment of ESCC.

Tumor-associated macrophage(TAM)-derived CCL22 induces FAK addiction in esophageal squamous cell carcinoma(ESCC)

Tumor cell dependence on activated oncogenes is considered a therapeutic target,but protumorigenic microenvironment-mediated cellular addiction to specific oncogenic signaling molecules remains to be further defined.Here,we showed that tumor-associated macrophages(TAMs)produced an abundance of C-C motif chemokine 22(CCL22),whose expression in the tumor stroma was positively associated with the level of intratumoral phospho-focal adhesion kinase(pFAK Tyr^(397)),tumor metastasis and reduced patient survival.Functionally,CCL22-stimulated hyperactivation of FAK was correlated with increased malignant progression of cancer cells.CCL22-induced addiction to FAK was demonstrated by the persistent suppression of tumor progression upon FAK-specific inhibition.Mechanistically,we identified that diacylglycerol kinaseα(DGKα)acted as a signaling adaptor to link the CCL22 receptor C-C motif chemokine receptor 4(CCR4)and FAK and promoted CCL22-induced activation of the FAK/AKT pathway.CCL22/CCR4 signaling activated the intracellular Ca^(2+)/phospholipase C-γ1(PLC-γ1)axis to stimulate the phosphorylation of DGKαat a tyrosine residue(Tyr^(335))and promoted the translocation of DGKαto the plasma membrane to assemble the DGKα/FAK signalosome,which critically contributed to regulating sensitivity to FAK inhibitors in cancer cells.The identification of TAM-driven intratumoral FAK addiction provides opportunities for utilizing the tumor-promoting microenvironment to achieve striking anticancer effects.