The tumor microenvironment (TME) is considered to be one of the vital mediators of tumor progression. Extracellular matrix (ECM), infiltrating immune cells, and stromal cells collectively constitute the complex ecosystem with varied biochemical and biophysical properties. The development of liver cancer is strongly tied with fibrosis and cirrhosis that alters the microenvironmental landscape, especially ECM composition. Enhanced deposition and cross-linking of type I collagen are frequently detected in patients with liver cancer and have been shown to facilitate tumor growth and metastasis by epithelial-to-mesenchymal transition. However, information on the effect of collagen enrichment on drug resistance is lacking. Thus, the present study has comprehensively illustrated phenotypical and mechanistic changes in an in vitro mimicry of collagen-enriched TME and revealed that collagen enrichment could induce 5-fluorouracil (5FU) and sorafenib resistance in liver cancer cells through hypoxia-induced up-regulation of lysyl oxidase-like 2 (LOXL2). LOXL2, an enzyme that facilitates collagen cross-linking, enhances cell adhesion-mediated drug resistance by activating the integrin alpha 5 (ITGA5)/focal adhesion kinase (FAK)/phosphoinositide 3-kinase (PI3K)/rho-associated kinase 1 (ROCK1) signaling axis. Conclusion: We demonstrated that inhibition of LOXL2 in a collagen-enriched microenvironment synergistically promotes the efficacy of sorafenib and 5FU through deterioration of focal adhesion signaling. These findings have clinical implications for developing LOXL2-targeted strategies in patients with chemoresistant liver cancer and especially for those patients with advanced fibrosis and cirrhosis.
Recent advances in single-cell sequencing technology have revolutionized our ability to acquire whole transcriptome data. However, uncovering the underlying transcriptional drivers and nonequilibrium driving forces of cell function directly from these data remains challenging. We address this by learning cell state vector fields from discrete single-cell RNA velocity to quantify the single-cell global nonequilibrium driving forces as landscape and flux. From single-cell data, we quantified the Waddington landscape, showing that optimal paths for differentiation and reprogramming deviate from the naively expected landscape gradient paths and may not pass through landscape saddles at finite fluctuations, challenging conventional transition state estimation of kinetic rate for cell fate decisions due to the presence of the flux. A key insight from our study is that stem/progenitor cells necessitate greater energy dissipation for rapid cell cycles and self-renewal, maintaining pluripotency. We predict optimal developmental pathways and elucidate the nucleation mechanism of cell fate decisions, with transition states as nucleation sites and pioneer genes as nucleation seeds. The concept of loop flux quantifies the contributions of each cycle flux to cell state transitions, facilitating the understanding of cell dynamics and thermodynamic cost, and providing insights into optimizing biological functions. We also infer cell–cell interactions and cell-type-specific gene regulatory networks, encompassing feedback mechanisms and interaction intensities, predicting genetic perturbation effects on cell fate decisions from single-cell omics data. Essentially, our methodology validates the landscape and flux theory, along with its associated quantifications, offering a framework for exploring the physical principles underlying cellular differentiation and reprogramming and broader biological processes through high-throughput single-cell sequencing experiments.
Cancer-associated fibroblasts (CAFs) play vital roles in establishing a suitable tumor microenvironment. In this study, RNA sequencing data revealed that CAFs could promote cell proliferation, angiogenesis, and ECM reconstitution by binding to integrin families and activating PI3K/AKT pathways in esophageal squamous cell carcinoma (ESCC). The secretions of CAFs play an important role in regulating these biological activities. Among these secretions, we found that MFGE8 is specifically secreted by CAFs in ESCC. Additionally, the secreted MFGE8 protein is essential in CAF-regulated vascularization, tumor proliferation, drug resistance, and metastasis. By binding to Integrin αVβ3/αVβ5 receptors, MFGE8 promotes tumor progression by activating both the PI3K/AKT and ERK/AKT pathways. Interestingly, the biological function of MFGE8 secreted by CAFs fully demonstrated the major role of CAFs in ESCC and its mode of mechanism, showing that MFGE8 could be a driver factor of CAFs in remodeling the tumor environment. In vivo treatment targeting CAFs-secreting MFGE8 or its receptor produced significant inhibitory effects on ESCC growth and metastasis, which provides an approach for the treatment of ESCC.
Abstract The invasion and metastasis affect the survival and prognosis of patients with esophageal carcinoma (ESCC). Through single-cell sequencing analysis of para-cancerous tissue, tumor tissue, normal lymph node tissue and lymph node metastasis tissue in 4 untreated ESCC patients, we found that APOC1 was specifically up-regulated in lymph node metastasis tissue and tumor tissue. In vitro and in vivo experiments revealed that APOC1 overexpression significantly promoted the migration and anti-ferroptosis function in ESCC. Also, APOC1 upregulation promotes M2 macrophage differentiation, Treg aggregation, and CD8 T cell immune inactivation in lymph node metastasis tissue. Mechanistically, APOC1 competes with NRF2 to bind Keap1, promoting nuclear translocation of NRF2 thus upregulating activation of the NRF2 pathway in tumor cells. For the lymph node metastasis tumor microenvironment, secreted APOC1 could upregulate the oxLDL which induced M2 macrophage polarization via CD36/JAK2/STAT3 axis. Overall, in this study, we explored the role and molecular mechanism of APOC1 in ESCC metastasis process which could provide a new molecular therapeutic approach to ESCC patients. Citation Format: Beilei Liu, Baifeng Zhang, Hongyu Zhou, Licheng Tan, Xiaona Fang, Lanqi Gong, Jie Luo, Jinlin Huang, Jiao Huang, Yuma Yang, Xinyuan Guan. Characterization of the molecular mechanism of APOC1 in anti-ferroptosis and lymph node microenvironment remodeling in ESCC metastasis process [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 629.
Abstract Hepatocellular carcinoma (HCC) ranks as the fifth most common cancer and the second leading cause of cancer-related mortality worldwide. The overall prognosis of HCC patients is very poor because it is susceptible to recurrence and metastasis. According to the cancer stem cell (CSC) model, there is a small subset of cancer cells within the tumor bulk that is responsible for tumor relapse and metastasis. CSCs represent cells that can self-renew, initiate tumors, and keep resistant to anti-cancer treatment. However, the fate and signatures of CSCs in HCC remain elusive. Our previous in vitro hepatocyte differentiation model successfully mimicked the liver developmental process from the stage of embryonic stem cells, endoderm, liver progenitor cells, and premature hepatocytes, together with one pair of nontumor and tumor tissue from an HCC patient. We found that the expression of keratin 17 (KRT17) reached its peak at the liver progenitor stage and was down-regulated along with liver development, which shared the same expression pattern with keratin 19 (CK19), a well-known HCC stemness-associated gene. Single-cell RNA sequencing in 9 HCC clinical samples from the GEO dataset revealed that KRT17 was expressed in less than 1% of tumor cells. Moreover, KRT17 shared similar expression patterns among hepatocytes, non-stem like HCC and stem like HCC subpopulations with a panel of hepatic stem cell markers and showed reverse trends with a list of hepatic markers. Clinically, KRT17 was highly expressed in cancer tissues compared to normal counterparts and positively correlated with poor overall survival. Functional assays indicated that KRT17 could considerably facilitate the self-renewal, growth, and metastasis properties of HCC both in vitro and in vivo. Also, KRT17 endowed HCC cells with enhanced resistance to sorafenib treatment. Moreover, the expressions of the CSC marker (CD133) and oncofetal drivers (NANOG and KLF4) were significantly upregulated upon KRT17 overexpression. Bioinformatic analysis using gene expression profiles of patients from the TCGA database revealed that development- and differentiation-related biological processes were dramatically enriched in KRT17-high patients. The underlying molecular mechanism of how KRT17 augments HCC stemness still needs further study. Overall, our study uncovered a new connection between KRT17 and HCC stemness and progression. KRT17 might be a novel marker of CSC and a prognostic biomarker for the treatment of HCC patients. Citation Format: Xiaona Fang, Shan Liu, Liuxian Ban, Jiao Huang, Jie Luo, Lanqi Gong, Baifeng Zhang, Beilei Liu, Jinlin Huang, Yuma Yang, Ching Ngar Wong, Qian Yan, Xin-Yuan Guan. Identification and characterization of the role of KRT17 in the stemness regulation of hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2441.
Overexpressing of ATP-binding cassette (ABC) transporters is the essential cause of multidrug resistance (MDR), which is a significant hurdle to the success of chemotherapy in many cancers. Therefore, inhibiting the activity of ABC transporters may be a logical approach to circumvent MDR. Olmutinib is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), which has been approved in South Korea for advanced EGFR T790M-positive non-small cell lung cancer (NSCLC). Here, we found that olmutinib significantly increased the sensitivity of chemotherapy drug in ABCG2-overexpressing cells. Furthermore, olmutinib could also increase the retention of doxorubicin (DOX) and rhodamine 123 (Rho 123) in ABC transporter subfamily G member 2 (ABCG2)-overexpressing cells. In addition, olmutinib was found to stimulate ATPase activity and inhibit photolabeling of ABCG2 with [125I]-iodoarylazidoprazosin (IAAP). However, olmutinib neither altered ABCG2 expression at protein and mRNA levels nor blocked EGFR, Her-2 downstream signaling of AKT and ERK. Importantly, olmutinib enhanced the efficacy of topotecan on the inhibition of S1-MI-80 cell xenograft growth. All the results suggest that olmutinib reverses ABCG2-mediated MDR by binding to ATP bind site of ABCG2 and increasing intracellular chemotherapeutic drug accumulation. Our findings encouraged to further clinical investigation on combination therapy of olmutinib with conventional chemotherapeutic drugs in ABCG2-overexpressing cancer patients.
'/%3e%3cuse xlink:href='%23a' transform='rotate(144 450 300)'/%3e%3cuse xlink:href='%23a' transform='rotate(216 450 300)'/%3e%3cuse xlink:href='%23a' transform='rotate(288 450 300)'/%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)