Leukemia inhibitory factor produced by fibroblasts within tumor stroma participates in invasion of oral squamous cell carcinoma

Super-Enhancer Driven LIF/LIFR-STAT3-SOX2 Regulatory Feedback Loop Promotes Cancer Stemness in Head and Neck Squamous Cell Carcinoma

Super-enhancers (SEs) have been recognized as key epigenetic regulators underlying cancer stemness and malignant traits by aberrant transcriptional control and promising therapeutic targets against human cancers. However, the SE landscape and their roles during head and neck squamous cell carcinoma (HNSCC) development especially in cancer stem cells (CSCs) maintenance remain underexplored yet. Here, we identify leukemia inhibitory factor (LIF)-SE as a representative oncogenic SE to activate LIF transcription in HNSCC. LIF secreted from cancer cells and cancer-associated fibroblasts promotes cancer stemness by driving SOX2 transcription in an autocrine/paracrine manner, respectively. Mechanistically, enhancer elements E1, 2, 4 within LIF-SE recruit SOX2/SMAD3/BRD4/EP300 to facilitate LIF transcription; LIF activates downstream LIFR-STAT3 signaling to drive SOX2 transcription, thus forming a previously unknown regulatory feedback loop (LIF-SE-LIF/LIFR-STAT3-SOX2) to maintain LIF overexpression and CSCs stemness. Clinically, increased LIF abundance in clinical samples correlate with malignant clinicopathological features and patient prognosis; higher LIF concentrations in presurgical plasma dramatically diminish following cancer eradication. Therapeutically, pharmacological targeting LIF-SE-LIF/LIFR-STAT3 significantly impairs tumor growth and reduces CSC subpopulations in xenograft and PDX models. Our findings reveal a hitherto uncharacterized LIF-SE-mediated auto-regulatory loop in regulating HNSCC stemness and highlight LIF as a novel noninvasive biomarker and potential therapeutic target for HNSCC.

The role of endoplasmic reticulum stress in the pathogenesis of oral diseases

The endoplasmic reticulum (ER) is crucial for protein synthesis, transport, and folding, as well as calcium storage, lipid and steroid synthesis, and carbohydrate metabolism. Endoplasmic reticulum stress (ERS) occurs when misfolded or unfolded proteins accumulate in the ER lumen due to increased protein secretion or impaired folding. While the role of ERS in disease pathogenesis has been widely studied, most research has focused on extraoral diseases, leaving the role of ERS in intraoral diseases unclear. This review examines the role of ERS in oral diseases and oral fibrosis pathogenesis. A systematic search of literature through July 2023 was conducted in the MEDLINE database (via PubMed) using specific terms related to ERS, oral diseases, and fibrosis. The findings were summarized in both table and narrative form. Emerging evidence indicates that ERS significantly contributes to the pathogenesis of oral diseases and fibrosis. ERS-induced dysregulation of protein folding and the unfolded protein response can lead to cellular dysfunction and inflammation in oral tissues. Understanding the relationship between ERS and oral disease pathogenesis could offer new therapeutic targets for managing oral health and fibrosis-related complications.

Leukemia inhibitory factor, a double-edged sword with therapeutic implications in human diseases

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine of the interleukin-6 (IL-6) superfamily. LIF was initially discovered as a factor to induce the differentiation of myeloid leukemia cells and thus inhibit their proliferation. Subsequent studies have highlighted the multi-functions of LIF under a wide variety of physiological and pathological conditions in a highly cell-, tissue-, and context-dependent manner. Emerging evidence has demonstrated that LIF plays an essential role in the stem cell niche, where it maintains the homeostasis and regeneration of multiple somatic tissues, including intestine, neuron, and muscle. Further, LIF exerts a crucial regulatory role in immunity and functions as a protective factor against many immunopathological diseases, such as infection, inflammatory bowel disease (IBD), and graft-verse-host disease (GVHD). It is worth noting that while LIF displays a tumor-suppressive function in leukemia, recent studies have highlighted the oncogenic role of LIF in many types of solid tumors, further demonstrating the complexities and context-dependent effects of LIF. In this review, we summarize the recent insights into the roles and mechanisms of LIF in stem cell homeostasis and regeneration, immunity, and cancer, and discuss the potential therapeutic options for human diseases by modulating LIF levels and functions.

The Pleiotropic role, functions and targeted therapies of LIF/LIFR axis in cancer: Old spectacles with new insights

The dysregulation of leukemia inhibitory factor (LIF) and its cognate receptor (LIFR) has been associated with multiple cancer initiation, progression, and metastasis. LIF plays a significant tumor-promoting role in cancer, while LIFR functions as a tumor promoter and suppressor. Epithelial and stromal cells secrete LIF via autocrine and paracrine signaling mechanism(s) that bind with LIFR and subsequently with co-receptor glycoprotein 130 (gp130) to activate JAK/STAT1/3, PI3K/AKT, mTORC1/p70s6K, Hippo/YAP, and MAPK signaling pathways. Clinically, activating the LIF/LIFR axis is associated with poor survival and anti-cancer therapy resistance. This review article provides an overview of the structure and ligands of LIFR, LIF/LIFR signaling in developmental biology, stem cells, cancer stem cells, genetics and epigenetics of LIFR, LIFR regulation by long non-coding RNAs and miRNAs, and LIF/LIFR signaling in cancers. Finally, neutralizing antibodies and small molecule inhibitors preferentially blocking LIF interaction with LIFR and antagonists against LIFR under pre-clinical and early-phase pre-clinical trials were discussed.

Leukemia Inhibitory Factor: An Important Cytokine in Pathologies and Cancer

Leukemia Inhibitory Factor (LIF) is a member of the IL-6 cytokine family and is expressed in almost every tissue type within the body. Although LIF was named for its ability to induce differentiation of myeloid leukemia cells, studies of LIF in additional diseases and solid tumor types have shown that it has the potential to contribute to many other pathologies. Exploring the roles of LIF in normal physiology and non-cancer pathologies can give important insights into how it may be dysregulated within cancers, and the possible effects of this dysregulation. Within various cancer types, LIF expression has been linked to hallmarks of cancer, such as proliferation, metastasis, and chemoresistance, as well as overall patient survival. The mechanisms behind these effects of LIF are not well understood and can differ between different tissue types. In fact, research has shown that while LIF may promote malignancy progression in some solid tumors, it can have anti-neoplastic effects in others. This review will summarize current knowledge of how LIF expression impacts cellular function and dysfunction to help reveal new adjuvant treatment options for cancer patients, while also revealing potential adverse effects of treatments targeting LIF signaling.

Cancer-Associated Fibroblasts Regulate the Plasticity of Breast Cancer Stemness through the Production of Leukemia Inhibitory Factor

Leukemia inhibitory factor (LIF), as a member of the interleukin-6 cytokine family, plays a complex role in solid tumors. However, the effect of LIF as a tumor microenvironment factor on plasticity control in breast cancer remains largely unknown. In this study, an in vitro investigation is conducted to determine the crosstalk between breast cancer cells and fibroblasts. Based on the results, cancer-associated fibroblasts are producers of LIF in the cocultivation system with breast cancer cells. Treatment with the CAF-CM and human LIF protein significantly promoted stemness through the dedifferentiation process and regaining of stem-cell-like properties. In addition, the results indicate that activation of LIFR signaling in breast cancer cells in the existence of CAF-secreted LIF can induce Nanog and Oct4 expression and increase breast cancer stem cell markers CD24-/CD44+. In contrast, suppression of the LIF receptor by human LIF receptor inhibition antibody decreased the cancer stem cell markers. We found that LIF was frequently overexpressed by CAFs and that LIF expression is necessary for dedifferentiation of breast cancer cell phenotype and regaining of cancer stem cell properties. Our results suggest that targeting LIF/LIFR signaling might be a potent therapeutic strategy for breast cancer and the prevention of tumor recurrence.

Biological implications of the immune factors in the tumour microenvironment of oral cancer

OBJECTIVE

The objective of this review is to decipher the biological implications of the immune factors in the tumour microenvironment in oral cancer. The restoration of balance between tumour tolerance and tumour eradication by the host immune cells is critical to provide effective therapeutic strategies.

DESIGN

The specific role of the stromal and the immune components in oral cancer was reviewed with a tailored search strategy using relevant keywords. The articles were retrieved from bibliometric databases indexed in PubMed, Scopus, and Embase. An in silico analysis was performed to identify potential drug candidates for immunotherapy, by accessing the Drug-Gene Interactions Database (DGIdb) using the rDGIdb package.

RESULTS

There is compelling evidence for the role of the cellular and extracellular components of the tumour microenvironment in inducing immunosuppression and progression of oral cancer. The druggable candidates specifically targeting the immune system are a viable option in the treatment of oral cancer as they can regulate the tumour microenvironment.

CONCLUSION

A complex interaction between the tumour and the immunological microenvironment influences the disease outcome in oral cancer. Targeting specific components of the immune system might be relevant, as immunotherapy may become the new standard of care for oral cancer.

Emerging Perspectives on Leukemia Inhibitory Factor and its Receptor in Cancer

Tumorigenesis and metastasis have deep connections to inflammation and inflammatory cytokines, but the mechanisms underlying these relationships are poorly understood. Leukemia Inhibitory Factor (LIF) and its receptor (LIFR), part of the interleukin-6 (IL-6) cytokine family, make up one such ill-defined piece of the puzzle connecting inflammation to cancer. Although other members of the IL-6 family have been shown to be involved in the metastasis of multiple types of cancer, the role of LIF and LIFR has been challenging to determine. Described by others in the past as enigmatic and paradoxical, LIF and LIFR are expressed in a diverse array of cells in the body, and the narrative surrounding them in cancer-related processes has been vague, and at times even contradictory. Despite this, recent insights into their functional roles in cancer have highlighted interesting patterns that may allude to a broader understanding of LIF and LIFR within tumor growth and metastasis. This review will discuss in depth the signaling pathways activated by LIF and LIFR specifically in the context of cancer-the purpose being to summarize recent literature concerning the downstream effects of LIF/LIFR signaling in a variety of cancer-related circumstances in an effort to begin teasing out the intricate web of contradictions that have made this pair so challenging to define.

The emerging role of leukemia inhibitory factor in cancer and therapy

Leukemia inhibitory factor (LIF) is a multi-functional cytokine of the interleukin-6 (IL-6) superfamily. Initially identified as a factor that inhibits the proliferation of murine myeloid leukemia cells, LIF displays a wide variety of important functions in a cell-, tissue- and context-dependent manner in many physiological and pathological processes, including regulating cell proliferation, pluripotent stem cell self-renewal, tissue/organ development and regeneration, neurogenesis and neural regeneration, maternal reproduction, inflammation, infection, immune response, and metabolism. Emerging evidence has shown that LIF plays an important but complex role in human cancers; while LIF displays a tumor suppressive function in some types of cancers, including leukemia, LIF is overexpressed and exerts an oncogenic function in many more types of cancers. Further, targeting LIF has been actively investigated as a novel strategy for cancer therapy. This review summarizes the recent advances in the studies on LIF in human cancers and its potential application in cancer therapy. A better understanding of the role of LIF in different types of cancers and its underlying mechanisms will help to develop more effective strategies for cancer therapy.

Metastasis-associated fibroblasts promote angiogenesis in metastasized pancreatic cancer via the CXCL8 and the CCL2 axes

The characteristic desmoplastic stroma of pancreatic ductal adenocarcinoma (PDAC) is a key contributor to its lethality. This stromal microenvironment is populated by cancer-associated fibroblasts (CAFs) that interact with cancer cells to drive progression and chemo-resistance. Research has focused on CAFs in the primary tumour but not in metastases, calling into question the role of analogous metastasis-associated fibroblasts (MAFs). We infer a role of MAFs in murine hepatic metastases following untargeted treatment with the anti-angiogenic drug sunitinib in vivo. Treated metastases were smaller and had fewer stromal cells, but were able to maintain angiogenesis and metastasis formation in the liver. Furthermore, sunitinib was ineffective at reducing MAFs alongside other stromal cells. We speculate that cancer cells interact with MAFs to maintain angiogenesis and tumour progression. Thus, we tested interactions between metastatic pancreatic cancer cells and fibroblasts using in vitro co-culture systems. Co-cultures enhanced fibroblast proliferation and induced angiogenesis. We identify carcinoma-educated fibroblasts as the source of angiogenesis via secretions of CXCL8 (aka IL-8) and CCL2 (aka MCP-1). Overall, we demonstrate that metastasis-associated fibroblasts have potential as a therapeutic target and highlight the CXCL8 and CCL2 axes for further investigation.

Role and Mechanism of LIF in Oral Squamous Cell Carcinoma Progression

Background: Metastasis is a severe problem in patients with oral squamous cell carcinoma (OSCC), which is the fifth most common cancer worldwide. Leukemia inhibitory factor (LIF) has been studied in different cancers, while the role of LIF in OSCC remains unclear. Methods: LIF expression was detected in 100 OSCC samples by immunohistochemistry. Effects of LIF on cell motility were evaluated in OSCC cell lines. High-throughput microarray analysis was also conducted. The correlation between LIF and the downstream effector was analyzed by real-time quantitative reverse transcription PCR. Results: Patients with OSCC who had lymph node metastasis or advanced cancer stages showed high LIF expression. OSCC patients with higher LIF expression, advanced stage, large tumor size, or lymph node metastasis had significantly shorter overall survival. LIF regulated cancer cell motilities through outside-in signaling. The inhibin beta A subunit (INHBA) gene was identified as a crucial downstream effector of LIF-promoted OSCC progression and restored migration and invasion abilities in LIF knockdown transfectants. Conclusion: LIF enhances regional lymphatic spread, thus leading to an advanced cancer stage. Regulation of LIF downstream molecules such as INHBA inhibits the invasion or migration ability of cancer cells. Thus, LIF can be a potential target in preventing cancer metastasis and spread.

Prognostic value of leukemia inhibitory factor and its receptor in pancreatic adenocarcinoma

Currently, the prognostic effects of leukemia inhibitory factor (LIF) and LIF receptor (LIFR) in pancreatic adenocarcinoma (PAAD) are not clear. In the present study, we utilized the large datasets from four public databases to investigate the expression of LIF and LIFR and their clinical significance in PAAD. Eight cohorts containing 1278 cases with PAAD were identified and the analysis results suggested that LIF was highly expressed while LIFR was lowly expressed in PAAD tissues compared with adjacent or normal tissues. Kaplan-Meier plot curves and univariate and multivariate Cox proportional hazards regression analyses indicated high LIF expression was associated with shorter overall survival (adjusted hazard ratio = 1.641, 95% CI: 1.399-1.925, p < 0.001) whereas high LIFR expression was associated with longer overall survival (adjusted hazard ratio = 0.653, 95% CI: 0.517-0.826, p < 0.001).

A Novel, Tumor-Induced Osteoclastogenesis Pathway Insensitive to Denosumab but Interfered by Cannabidiol

Bone metabolism is strictly regulated, and impaired regulation caused by hormonal imbalances induces systemic bone loss. Local bone loss caused by tumor invasion into bone is suggested to be induced by the generation of cytokines, which affect bone metabolism, by tumor cells. The major cause of systemic and local bone losses is excess bone resorption by osteoclasts, which differentiate from macrophages by receptor activator of nuclear factor kappa-B ligand (RANKL) or tumor necrosis factor-alpha (TNF-α). We previously found a novel pathway for tumor-induced osteoclastogenesis targeting osteoclast precursor cells (OPCs). Tumor-induced osteoclastogenesis was resistant to RANKL and TNF-α inhibitors. In the present study, we confirmed that exosomes derived from oral squamous cell carcinoma (OSCC) cells induced osteoclasts from OPCs. We also showed that the depletion of exosomes from culture supernatants of OSCC cells partially interfered with osteoclastogenesis, and cannabidiol, an innoxious cannabinoid without psychotropic effects, almost completely suppressed tumor-induced osteoclastogenesis. Osteoclastogenesis and its interference by cannabidiol were independent of the expression of nuclear factor of T cell c1 (NFATc1). These results show that osteoclastogenesis induced by OSCC cells targeting OPCs is a novel osteoclastogenic pathway independent of NFATc1 expression that is partially caused by tumor-derived exosomes and suppressed by cannabidiol.

Cancer‑associated fibroblast‑derived exosomal miR‑382‑5p promotes the migration and invasion of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC), with high potential for metastasis, is the most common malignant tumor of the head and neck. Cancer‑associated fibroblasts (CAFs) are the main stromal cells in the microenvironment and aggravate tumor progression. However, whether CAFs are associated with the progression of OSCC remains unknown and the underlying mechanism remains unclear. In the present study, the role of CAFs in mediating OSCC cell migration and invasion was investigated, and the participation of exosomal miR‑382‑5p in this process was elucidated. In this study, according to the α‑SMA staining with immunohistochemistry, 47 OSCC patients were divided into CAFs‑rich and CAFs poor groups, and association of CAF density and clinicopathologic features of the OSCC patients were analyzed with Pearson χ2 test. Transwell assay was used for evaluating cell migration and invasion ability of OSCC cells after being co‑cultured with NFs or CAFs, or after added exosomes. qPCR was used to detect the expression of miR‑382‑5p. Western blot analysis was used to measure the expression of migration and invasion‑associated proteins. In the present study, the CAF density in tumor tissues was found to be relevant to OSCC lymph node metastasis and TNM stage. Furthermore, we revealed that miR‑382‑5p was overexpressed in CAFs compared with that in fibroblasts of adjacent normal tissue and miR‑382‑5p overexpression was responsible for OSCC cell migration and invasion. Finally, we demonstrated that CAF‑derived exosomes transported miR‑382‑5p to OSCC cells. The present study confirmed a new mechanism of CAF‑facilitated OSCC progression and may be beneficial for identifying new cancer therapeutic targets.

A new osteoclastogenesis pathway induced by cancer cells targeting osteoclast precursor cells

The precise mechanism of osteolysis induced by tumors infiltrating into the bone remains unclear. The main hypothesis is that tumor cells generate receptor activator of nuclear factor kappa-B ligand (RANKL), tumor necrosis factor-alpha (TNF-α), or other molecules that activate the expression of RANKL in osteoblasts, osteocytes, or bone marrow stromal cells. Administration of bisphosphonates or anti-RANKL antibody drugs, which suppress systemic bone resorption, prevents osteolysis induced by tumors infiltrating into the bone. However, these therapeutic agents may cause medication-related osteonecrosis of the jaw. In this study, we found a novel tumor-associated osteoclastogenesis pathway in osteoclast precursor cells. Co-culture with human oral squamous cell carcinoma cells, 3A or NEM, or culture with each of their conditioned medium induced many osteoclasts from osteoclast precursor cells, which were generated by a 24-h pretreatment of RANKL or TNF-α. Osteoprotegerin, a decoy RANKL receptor, denosumab, an anti-RANKL antibody drug, and infliximab, an anti-TNF-α antibody drug, did not prevent this tumor-associated osteoclastogenesis. Quantitative RT-PCR analysis showed that the expression of NFATc1 was decreased in this tumor-associated osteoclastogenesis, which was suggested to be independent of NFATc1. These results revealed a novel pathway for tumor-associated osteoclastogenesis, which may be a new therapeutic target for osteolysis induced by tumors infiltrating into the bone without affecting systemic bone metabolism.

RNA Sequencing of Carboplatin- and Paclitaxel-Resistant Endometrial Cancer Cells Reveals New Stratification Markers and Molecular Targets for Cancer Treatment

Despite advances in surgical technique and adjuvant treatment, endometrial cancer has recently seen an increase in incidence and mortality in the USA. The majority of endometrial cancers can be cured by surgery alone or in combination with adjuvant chemo- or radiotherapy; however, a subset of patients experience recurrence for reasons that remain unclear. Recurrence is associated with chemoresistance to carboplatin and paclitaxel and consequentially, high mortality. Understanding the pathways involved in endometrial cancer chemoresistance is paramount for the identification of biomarkers and novel molecular targets for this disease. Here, we generated the first matched pairs of carboplatin-sensitive/carboplatin-resistant and paclitaxel-sensitive/paclitaxel-resistant endometrial cancer cells and subjected them to bulk RNA sequencing analysis. We found that 45 genes are commonly upregulated in carboplatin- and paclitaxel-resistant cells as compared to controls. Of these, the leukemia inhibitory factor, (LIF), the protein tyrosine phosphatase type IVA, member 3 (PTP4A3), and the transforming growth factor beta 1 (TGFB1) showed a highly significant correlation between expression level and endometrial cancer overall survival (OS) and can stratify the 545 endometrial cancer patients in the TCGA cohort into a high-risk and low-risk-cohorts. Additionally, four genes within the 45 upregulated chemoresistance-associated genes are ADAMTS5, MICAL2, STAT5A, and PTP4A3 codes for proteins for which small-molecule inhibitors already exist. We identified these proteins as molecular targets for chemoresistant endometrial cancer and showed that treatment with their correspondent inhibitors effectively killed otherwise chemoresistant cells. Collectively, these findings underline the utility of matched pair of chemosensitive and chemoresistant cancer cells to identify markers for endometrial cancer risk stratification and to serve as a pharmacogenomics model for identification of alternative chemotherapy approaches for treatment of patients with recurrent disease.