Cancer-Associated Fibroblasts Provide a Stromal Niche for Liver Cancer Organoids That Confers Trophic Effects and Therapy Resistance.

Cancer-associated fibroblasts (CAFs) play a key role in the cancer process, but the research progress is hampered by the paucity of preclinical models that are essential for mechanistic dissection of cancer cell-CAF interactions. Here, we aimed to establish 3-dimensional (3D) organotypic co-cultures of primary liver tumor-derived organoids with CAFs, and to understand their interactions and the response to treatment. Liver tumor organoids and CAFs were cultured from murine and human primary liver tumors. 3D co-culture models of tumor organoids with CAFs and Transwell culture systems were established in vitro. A xenograft model was used to investigate the cell-cell interactions in vivo. Gene expression analysis of CAF markers in our hepatocellular carcinoma cohort and an online liver cancer database indicated the clinical relevance of CAFs. To functionally investigate the interactions of liver cancer cells with CAFs, we successfully established murine and human 3D co-culture models of liver tumor organoids with CAFs. CAFs promoted tumor organoid growth in co-culture with direct cell-cell contact and in a Transwell system via paracrine signaling. Vice versa, cancer cells secrete paracrine factors regulating CAF physiology. Co-transplantation of CAFs with liver tumor organoids of mouse or human origin promoted tumor growth in xenograft models. Moreover, tumor organoids conferred resistance to clinically used anticancer drugs including sorafenib, regorafenib, and 5-fluorouracil in the presence of CAFs, or the conditioned medium of CAFs. We successfully established murine and human 3D co-culture models and have shown robust effects of CAFs in liver cancer nurturing and treatment resistance.

Liu J ，Li P ，Wang L ，Li M ，Ge Z ，Noordam L ，Lieshout R ，Verstegen MMA ，Ma B ，Su J ，Yang Q ，Zhang R ，Zhou G ，Carrascosa LC ，Sprengers D ，IJzermans JNM ，Smits R ，Kwekkeboom J ，van der Laan LJW ，Peppelenbosch MP ，Pan Q ，Cao W ... -  《Cellular and Molecular Gastroenterology and Hepatology》

Cancer-associated fibroblasts nurture LGR5 marked liver tumor-initiating cells and promote their tumor formation, growth, and metastasis.

Zhang M ，Fang Y ，Fu X ，Liu J ，Liu Y ，Zhu Z ，Ni Y ，Yao M ，Pan Q ，Cao W ，Li Z ，Dong C ... -  《Cancer Medicine》

Resolvin D1 prevents epithelial-mesenchymal transition and reduces the stemness features of hepatocellular carcinoma by inhibiting paracrine of cancer-associated fibroblast-derived COMP.

Sun L ，Wang Y ，Wang L ，Yao B ，Chen T ，Li Q ，Liu Z ，Liu R ，Niu Y ，Song T ，Liu Q ，Tu K ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

The BAFF/NFκB axis is crucial to interactions between sorafenib-resistant HCC cells and cancer-associated fibroblasts.

The tumor microenvironment affects malignancy in hepatocellular carcinoma (HCC) cells, and cancer-associated fibroblasts (CAFs) play an important role in the microenvironment. As recent studies indicated a difference between CAFs isolated from chemoresistant and non-resistant cancer tissues, therefore we investigated the intracellular mechanism in resistant HCC co-cultured CAFs and interactions between these CAFs with cancer cells. We established a sorafenib-resistant (SR) Huh7 (human HCC) cell line, and characterized it with cytokine assays, then developed CAFs by co-culturing human hepatic stellate cells with resistant or parental Huh7 cells. The 2 types of CAFs were co-cultured with parental Huh7 cells, thereafter the cell viability of these Huh7 cells was checked under sorafenib treatment. The SR Huh7 (Huh7SR ) cells expressed increased B-cell activating factor (BAFF), which promoted high expression of CAF-specific markers in Huh7SR -co-cultured CAFs, showed activated BAFF, BAFF-R, and downstream of the NFκB-Nrf2 pathway, and aggravated invasion, migration, and drug resistance in co-cultured Huh7 cells. When we knocked down BAFF expression in Huh7SR cells, the previously increased malignancy and BAFF/NFκB axis in Huh7SR -co-cultured CAFs reversed, and enhanced chemoresistance in co-cultured Huh7 cells returned as well. In conclusion, the BAFF/NFκB pathway was activated in CAFs co-cultured with cell-culture medium from resistant Huh7, which promoted chemoresistance, and increased the malignancy in co-cultured non-resistant Huh7 cells. This suggests that the BAFF/NFκB axis in CAFs might be a potential therapeutic target in chemoresistance of HCC.

Gao L ，Morine Y ，Yamada S ，Saito Y ，Ikemoto T ，Tokuda K ，Miyazaki K ，Okikawa S ，Takasu C ，Shimada M ... -  《-》

Vascular mimicry formation is promoted by paracrine TGF-β and SDF1 of cancer-associated fibroblasts and inhibited by miR-101 in hepatocellular carcinoma.

Vascular mimicry (VM) describes the phenomenon that tumor cells but not endothelial cells form vascular-like channels, which provide blood perfusion for tumor tissues. VM is associated with tumor growth, metastasis and worse survival of different cancers. The mechanisms of VM formation remain largely unknown. We showed that the conditioned medium of cancer-associated fibroblast (CM-CAF) promoted tumor cells to form capillary-like structure in vitro. Consistently, co-implantation of CAFs with tumor cells significantly enhanced VM formation in mouse xenografts, and higher amount of CAFs was found in VM+ human HCC tissues compared to VM- ones. However, the CM-CAF-promoted VM formation was attenuated when TGF-β or SDF1 signaling was abrogated. Similar to CM-CAF, recombinant TGF-β1 and SDF1 induced VM formation. We further disclosed that the CAF-secreted TGF-β and SDF1 enhanced the expression of VE-cadherin, MMP2 and laminin5γ2 via TGF-βR1 and CXCR4 in tumor cells, thereby promoted VM formation. Moreover, tumor cells with high activity of self-sustaining TGF-β signaling displayed strong capability of VM formation. Subsequent investigations showed that miR-101, which was down-regulated in both tumor cells and CAFs, suppressed the CAF-promoted VM formation in vitro and in vivo. Gain- and loss-of-function analyses revealed that miR-101 attenuated TGF-β signaling transduction by targeting TGF-βR1 and Smad2 in tumor cells, and simultaneously abrogated SDF1 signaling by suppressing SDF1 expression in CAFs and inhibiting VE-cadherin expression in tumor cells. Our findings suggest that the miR-101-TGF-β/SDF1-VE-cadherin/MMP2/LAMC2 networks regulate VM formation and represent the potential targets for cancer therapy.

Yang J ，Lu Y ，Lin YY ，Zheng ZY ，Fang JH ，He S ，Zhuang SM ... -  《-》