IFNγ inhibits fibroblast-leading tumor cell invasion through downregulating N-cadherin

Stromal cells in the tumor microenvironment: accomplices of tumor progression?

The tumor microenvironment (TME) is made up of cells and extracellular matrix (non-cellular component), and cellular components include cancer cells and non-malignant cells such as immune cells and stromal cells. These three types of cells establish complex signals in the body and further influence tumor genesis, development, metastasis and participate in resistance to anti-tumor therapy. It has attracted scholars to study immune cells in TME due to the significant efficacy of immune checkpoint inhibitors (ICI) and chimeric antigen receptor T (CAR-T) in solid tumors and hematologic tumors. After more than 10 years of efforts, the role of immune cells in TME and the strategy of treating tumors based on immune cells have developed rapidly. Moreover, ICI have been recommended by guidelines as first- or second-line treatment strategies in a variety of tumors. At the same time, stromal cells is another major class of cellular components in TME, which also play a very important role in tumor metabolism, growth, metastasis, immune evasion and treatment resistance. Stromal cells can be recruited from neighboring non-cancerous host stromal cells and can also be formed by transdifferentiation from stromal cells to stromal cells or from tumor cells to stromal cells. Moreover, they participate in tumor genesis, development and drug resistance by secreting various factors and exosomes, participating in tumor angiogenesis and tumor metabolism, regulating the immune response in TME and extracellular matrix. However, with the deepening understanding of stromal cells, people found that stromal cells not only have the effect of promoting tumor but also can inhibit tumor in some cases. In this review, we will introduce the origin of stromal cells in TME as well as the role and specific mechanism of stromal cells in tumorigenesis and tumor development and strategies for treatment of tumors based on stromal cells. We will focus on tumor-associated fibroblasts (CAFs), mesenchymal stem cells (MSCs), tumor-associated adipocytes (CAAs), tumor endothelial cells (TECs) and pericytes (PCs) in stromal cells.

ZIP1+ fibroblasts protect lung cancer against chemotherapy via connexin-43 mediated intercellular Zn2+ transfer

Tumour-stroma cell interactions impact cancer progression and therapy responses. Intercellular communication between fibroblasts and cancer cells using various soluble mediators has often been reported. In this study, we find that a zinc-transporter (ZIP1) positive tumour-associated fibroblast subset is enriched after chemotherapy and directly interconnects lung cancer cells with gap junctions. Using single-cell RNA sequencing, we identify several fibroblast subpopulations, among which Zip1+ fibroblasts are highly enriched in mouse lung tumours after doxorubicin treatment. ZIP1 expression on fibroblasts enhances gap junction formation in cancer cells by upregulating connexin-43. Acting as a Zn2+ reservoir, ZIP1+ fibroblasts absorb and transfer Zn2+ to cancer cells, leading to ABCB1-mediated chemoresistance. Clinically, ZIP1high stromal fibroblasts are also associated with chemoresistance in human lung cancers. Taken together, our results reveal a mechanism by which fibroblasts interact directly with tumour cells via gap junctions and contribute to chemoresistance in lung cancer.

Role of interferon-gamma (IFN-γ) and IFN-γ receptor 1/2 (IFNγR1/2) in regulation of immunity, infection, and cancer development: IFN-γ-dependent or independent pathway

IFN-γ, a soluble cytokine being produced by T lymphocytes, macrophages, mucosal epithelial cells, or natural killer cells, is able to bind to the IFN-γ receptor (IFNγR) and in turn activate the Janus kinase (JAK)-signal transducer and transcription protein (STAT) pathway and induce expression of IFN-γ-stimulated genes. IFN-γ is critical for innate and adaptive immunity and aberrant IFN-γ expression and functions have been associated with different human diseases. However, the IFN-γ/IFNγR signaling could be a double-edged sword in cancer development because the tissue microenvironments could determine its anti- or pro-tumorigenic activities. The IFNγR protein consists of two IFNγR1 and IFNγR2 chains, subunits of which play different roles under certain conditions. This review assessed IFNγR polymorphisms, expression and functions in development and progression of various human diseases in an IFN-γ-dependent or independent manner. This review also discussed tumor microenvironment, microbial infection, and vital molecules in the IFN-γ upstream signaling that might regulate IFNγR expression, drug resistance, and druggable strategy, to provide evidence for further application of IFNγR.

Exosomes produced by melanoma cells significantly influence the biological properties of normal and cancer-associated fibroblasts

The incidence of cutaneous malignant melanoma is increasing worldwide. While the treatment of initial stages of the disease is simple, the advanced disease frequently remains fatal despite novel therapeutic options . This requires identification of novel therapeutic targets in melanoma. Similarly to other types of tumours, the cancer microenvironment plays a prominent role and determines the biological properties of melanoma. Importantly, melanoma cell-produced exosomes represent an important tool of intercellular communication within this cancer ecosystem. We have focused on potential differences in the activity of exosomes produced by melanoma cells towards melanoma-associated fibroblasts and normal dermal fibroblasts. Cancer-associated fibroblasts were activated by the melanoma cell-produced exosomes significantly more than their normal counterparts, as assessed by increased transcription of genes for inflammation-supporting cytokines and chemokines, namely IL-6 or IL-8. We have observed that the response is dependent on the duration of the stimulus via exosomes and also on the quantity of exosomes. Our study demonstrates that melanoma-produced exosomes significantly stimulate the tumour-promoting proinflammatory activity of cancer-associated fibroblasts. This may represent a potential new target of oncologic therapy .

HIF-1α is necessary for activation and tumour-promotion effect of cancer-associated fibroblasts in lung cancer

Cancer‐associated fibroblasts (CAFs) activation is crucial for the establishment of a tumour promoting microenvironment, but our understanding of CAFs activation is still limited. In this study, we found that hypoxia‐inducible factor‐1α (HIF‐1α) was highly expressed in CAFs of human lung cancer tissues and mouse spontaneous lung tumour. Accordingly, enhancing the expression of HIF‐1α in fibroblasts via hypoxia induced the conversion of normal fibroblasts into CAFs. HIF‐1α‐specific inhibitor or HIF‐1α knockout (KO) significantly attenuated CAFs activation, which was manifested by the decreased expression of COL1A2 and α‐SMA. In vivo, during tumour formation, the expression of Ki‐67 and proliferating cell nuclear antigen (PCNA) in the tumour tissue with HIF‐1α KO fibroblasts was significantly lower than that of normal fibroblasts. Moreover, HIF‐1α in fibroblasts could activate the NF‐κB signalling pathway and enhance a subsequent secretion of CCL5, thus promoting the tumour growth. In conclusion, our results suggest that HIF‐1α is essential for the activation and tumour‐promotion function of CAFs in lung cancer (LC). And targeting HIF‐1α expression on CAFs may be a promising strategy for LC therapy.

Low SCRIB expression in fibroblasts promotes invasion of lung cancer cells

AIMS

Cancer associated fibroblasts (CAFs) play a crucial role in lung tumor development, but the underlying mechanism is still not fully understood.

MAIN METHODS

SCRIB expression in the CAFs of human lung cancer tissues was examined by immunohistochemistry (IHC). A coculture of mouse Lewis lung cancer cells (LLC) and fibroblasts was used to investigate SCRIB expression in cocultured fibroblasts. Proliferation, scratch wound, and transwell assays were used to examine the proliferation, migration and invasion ability of SCRIB knockdown fibroblasts and their effects on LLC. A 3D-coculture system and co-injection xenograft model were used to examine LLC invasion. RNA sequencing and transwell experiments were used to explore the molecules that may participate in LLC invasion.

KEY FINDINGS

Herein, we found that the low expression of SCRIB in CAFs is correlated with advanced tumor stages and poor survival for human lung squamous cell carcinoma. SCRIB expression in fibroblasts is drastically downregulated by LLC cells. SCRIB knockdown fibroblasts not only enhance invasion but also facilitate LLC invasion in a 3D-coculture system and in an in vivo subcutaneous transplantation model. The upregulation of asporin in SCRIB knockdown fibroblasts is involved in LLC invasion in vitro.

SIGNIFICANCE

Collectively, the results indicate that fibroblasts with low SCRIB expression promote lung cancer cell invasion, which suggests that the downregulated expression of SCRIB may represent one of the important characteristics of tumor-promoting CAFs in lung squamous cell cancer.