Cutaneous leukemia inhibitory factor and its potential role in the development of skin tumors

Integrative analysis of RNA-sequencing and microarray for the identification of adverse effects of UVB exposure on human skin

Background

Ultraviolet B (UVB) from sunlight represents a major environmental factor that causes toxic effects resulting in structural and functional cutaneous abnormalities in most living organisms. Although numerous studies have indicated the biological mechanisms linking UVB exposure and cutaneous manifestations, they have typically originated from a single study performed under limited conditions.

Methods

We accessed all publicly accessible expression data of various skin cell types exposed to UVB, including skin biopsies, keratinocytes, and fibroblasts. We performed biological network analysis to identify the molecular mechanisms and identify genetic biomarkers.

Results

We interpreted the inflammatory response and carcinogenesis as major UVB-induced signaling alternations and identified three candidate biomarkers (IL1B, CCL2, and LIF). Moreover, we confirmed that these three biomarkers contribute to the survival probability of patients with cutaneous melanoma, the most aggressive and lethal form of skin cancer.

Conclusion

Our findings will aid the understanding of UVB-induced cutaneous toxicity and the accompanying molecular mechanisms. In addition, the three candidate biomarkers that change molecular signals due to UVB exposure of skin might be related to the survival rate of patients with cutaneous melanoma.

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.

Leukemia inhibitory factor regulates marmoset induced pluripotent stem cell proliferation via a PI3K/‌Akt‑dependent Tbx‑3 activation pathway

Leukemia inhibitory factor (LIF) is the most pleiotropic cytokine of the interleukin-6 family, and is widely used to establish and maintain pluripotent stem cells, particularly mouse pluripotent stem cells. However, no reports have fully elucidated the application of LIF in marmoset induced pluripotent stem cell (iPSC) culture, particularly the underlying mechanisms. To demonstrate the feasibility of the application of LIF to marmoset iPSCs, the present study assessed these cells in the presence of LIF. Cell proliferation was measured using MTT assay, cell apoptosis was determined by flow cytometric analysis of fluorescein isothiocyanate Annexin V staining and the differentially expressed genes were analysed using Digital Gene Expression (DGE) analysis. The altered expression of pluripotency-associated genes was confirmed by reverse transcription-quantitative polymerase chain reaction and western blot analysis. Furthermore, following treatment with LY294002, cell proliferation was measured by MTT assay and protein levels were confirmed by western blot analysis. The results showed that LIF significantly promoted the number of proliferating cells, but had no effect on apoptosis. Digital Gene Expression analysis was used to examine the differentially expressed genes of marmoset iPSCs in the presence of LIF. The results showed that the pluripotency-associated transcription factor-encoding gene T-box 3 (Tbx-3) was activated by LIF. Notably, LIF increased the levels of phosphorylated (p-)AKT and Tbx-3 in the marmoset iPSCs. Furthermore, pretreatment with LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), significantly impaired the LIF-induced upregulation of p-AKT and Tbx-3 in the marmoset iPSCs, suggesting that the PI3K/Akt signaling pathway is involved in this regulation. Taken together, the results suggested that LIF is effective in maintaining marmoset iPSCs in cultures, which is associated with the activation of Tbx-3 through regulation of the PI3K/Akt signaling pathway.

Leukemia inhibitory factor protects cholangiocarcinoma cells from drug-induced apoptosis via a PI3K/AKT-dependent Mcl-1 activation

Cholangiocarcinoma is an aggressive, strongly chemoresistant liver malignancy. Leukemia inhibitory factor (LIF), an IL-6 family cytokine, promotes progression of various carcinomas. To investigate the role of LIF in cholangiocarcinoma, we evaluated the expression of LIF and its receptor (LIFR) in human samples. LIF secretion and LIFR expression were assessed in established and primary human cholangiocarcinoma cell lines. In cholangiocarcinoma cells, we tested LIF effects on proliferation, invasion, stem cell-like phenotype, chemotherapy-induced apoptosis (gemcitabine+cisplatin), expression levels of pro-apoptotic (Bax) and anti-apoptotic (Mcl-1) proteins, with/without PI3K inhibition, and of pSTAT3, pERK1/2, pAKT. LIF effect on chemotherapy-induced apoptosis was evaluated after LIFR silencing and Mcl-1 inactivation.

Results show that LIF and LIFR expression were higher in neoplastic than in control cholangiocytes; LIF was also expressed by tumor stromal cells. LIF had no effects on cholangiocarcinoma cell proliferation, invasion, and stemness signatures, whilst it counteracted drug-induced apoptosis. Upon LIF stimulation, decreased apoptosis was associated with Mcl-1 and pAKT up-regulation and abolished by PI3K inhibition. LIFR silencing and Mcl-1 blockade restored drug-induced apoptosis.

In conclusion, autocrine and paracrine LIF signaling promote chemoresistance in cholangiocarcinoma by up-regulating Mcl-1 via a novel STAT3- and MAPK-independent, PI3K/AKT-dependent pathway. Targeting LIF signaling may increase CCA responsiveness to chemotherapy.

HIF-2α mediates hypoxia-induced LIF expression in human colorectal cancer cells

Leukemia inhibitory factor (LIF), a multi-functional cytokine, has a complex role in cancer. While LIF induces the differentiation of several myeloid leukemia cells and inhibits their growth, it also promotes tumor progression, metastasis and chemoresistance in many solid tumors. LIF is frequently overexpressed in a variety of human tumors and its overexpression is often associated with poor prognosis of patients. Currently, the mechanism for LIF overexpression in tumor cells is not well-understood. Here, we report that hypoxia, a hallmark of solid tumors, induced LIF mRNA expression in human colorectal cancer cells. Analysis of LIF promoter revealed several hypoxia-responsive elements (HREs) that can specifically interact with and be transactivated by HIF-2α but not HIF-1α. Consistently, ectopic expression of HIF-2α but not HIF-1α transcriptionally induced LIF expression levels in cells. Knockdown of endogenous HIF-2α but not HIF-1α by siRNA largely abolished the induction of LIF by hypoxia in cells. Furthermore, there is a strong association of HIF-2α overexpression with LIF overexpression in human colorectal cancer specimens. In summary, results from this study demonstrate that hypoxia induces LIF expression in human cancer cells mainly through HIF-2α, which could be an important underlying mechanism for LIF overexpression in human cancers.

The leukemia inhibitory factor (LIF) and p21 mediate the TGFβ tumor suppressive effects in human cutaneous melanoma

BACKGROUND

Cutaneous melanoma is the most lethal skin cancer and its incidence in developed countries has dramatically increased over the past decades. Localized tumors are easily treated by surgery, but advanced melanomas lack efficient treatment and are associated with very poor outcomes. Thus, understanding the processes underlying melanoma development and progression is critical. The Transforming Growth Factor beta (TGFβ) acts as a potent tumor suppressor in human melanoma, by inhibiting cell growth and preventing cellular migration and invasion.

METHODS

In this study, we aimed at elucidating the molecular mechanisms underlying TGFβ-mediated tumor suppression. Human cutaneous melanoma cell lines, derived from different patients, were used to assess for cell cycle analysis, apoptosis/caspase activity and cell migration. Techniques involved immunoblotting, immunohistochemistry, real time PCR and luciferase reporter assays.

RESULTS

We found the leukemia inhibitory factor (LIF) to be strongly up-regulated by TGFβ in melanoma cells, defining LIF as a novel TGFβ downstream target gene in cutaneous melanoma. Interestingly, we also showed that TGFβ-mediated LIF expression is required for TGFβ-induced cell cycle arrest and caspase-mediated apoptosis, as well as for TGFβ-mediated inhibition of cell migration. Moreover, we found that TGFβ-mediated LIF expression leads to activation of transcription of the cell cycle inhibitor p21 in a STAT3-dependent manner, and further showed that p21 is required for TGFβ/LIF-mediated cell cycle arrest and TGFβ-induced gene activation of several pro-apoptotic genes.

CONCLUSIONS

Together, our results define the LIF/p21 signaling cascade as a novel tumor suppressive-like pathway in melanoma, acting downstream of TGFβ to regulate cell cycle arrest and cell death, further highlight new potential therapeutic strategies for the treatment of cutaneous melanoma.

LIF promotes tumorigenesis and metastasis of breast cancer through the AKT-mTOR pathway

Leukemia inhibitory factor (LIF) is a multi-functional cytokine protein. The role of LIF in tumorigenesis is not well-understood. Here, we found that LIF promotes tumorigenesis and metastasis of breast cancer. LIF promotes cell proliferation and anchorage-independent growth of breast cancer cells in vitro, and the growth of xenograft breast tumors in vivo. LIF also promotes invasion and migration of breast cancer cells in vitro and metastasis of breast cancer in vivo. We found that LIF activates the AKT-mTOR signaling pathway to promote tumorigenesis and metastasis of breast cancer. Inhibiting the AKT activity can largely block the activation of the mTOR pathway by LIF, suggesting that LIF activates the mTOR pathway through AKT. Inhibiting the AKT activity as well as inhibiting the mTOR activity largely block the promoting effect of LIF on tumorigenesis and metastasis. Furthermore, overexpression of LIF is significantly associated with a poorer relapse free survival in breast cancer patients. Taken together, our data strongly suggest that LIF plays an important role in the tumorigenesis and metastasis of breast cancer, and could be an important prognostic marker for breast cancer.

LIF-dependent signaling: new pieces in the Lego

LIF, a member of the IL6 family of cytokine, displays pleiotropic effects on various cell types and organs. Its critical role in stem cell models (e.g.: murine ES, human mesenchymal cells) and its essential non redundant function during the implantation process of embryos, in eutherian mammals, put this cytokine at the core of many studies aiming to understand its mechanisms of action, which could benefit to medical applications. In addition, its conservation upon evolution raised the challenging question concerning the function of LIF in species in which there is no implantation. We present the recent knowledge about the established and potential functions of LIF in different stem cell models, (embryonic, hematopoietic, mesenchymal, muscle, neural stem cells and iPSC). We will also discuss EVO-DEVO aspects of this multifaceted cytokine.

Associations between promoter polymorphism -106A/G of interleukin-11 receptor alpha and papillary thyroid cancer in Korean population

BACKGROUND

The interleukin11 (IL11) and IL11 receptor alpha (IL11RA) are involved in cellular growth, differentiation, invasiveness, and tumor progression in several tumors. We investigated whether coding single nucleotide polymorphisms (cSNPs) of IL11 and promoter SNP IL11RA would contribute to the development of papillary thyroid cancer (PTC). We also assessed the relationships between IL11 and IL11RA SNPs and the clinicopathologic characteristics of PTC.

METHODS

One coding SNP, designated as rs1126757, Ala82Ala, in IL11 and one promoter SNP, designated as rs1061758, -106A/G, in IL11RA were genotyped using direct sequencing in 94 patents with PTC and 213 patients without PTC (controls). Genetic data were analyzed using commercially available software. The patients with PTC were dichotomized and compared with respect to clinicopathologic characteristics of PTC.

RESULTS

We found an association between PTC and the coding SNP(rs1061758) in IL11RA (codominant model 1 [G/G vs. A/G], odds ratio [OR] = 2.91, 95% confidence interval [CI], 1.44-5.89; P = .003; codominant model 2 [G/G vs. A/A], OR = 2.95, 95% CI, 1.30-6.72; P = .01; and dominant model, OR = 2.92, 95% CI, 1.47-5.80; P = .002). Moreover, SNP rs1061758 in IL11RA was associated with the multifocality of PTC (codominant model 2 [A/A vs. G/G], OR = 9.56, 95% CI, 1.77-51.69; P = .009; and recessive model, OR = 7.22, 95% CI, 1.72-30.3; P = .007). Genotype and allele analyses of SNP variant rs1126757 in IL11 revealed no statistically significant differences between patients with PTC and controls.

CONCLUSION

Our results suggest that an IL11RA promoter polymorphism--rs1061758--may be associated with the risk of PTC in the Korean population. In addition, rs1061758 might be related to the multifocality of PTC.

A comparative study of leukaemia inhibitory factor and interleukin-1alpha intracellular content in a human keratinocyte cell line after exposure to cosmetic fragrances and sodium dodecyl sulphate

According to European laws animal testing in cosmetic industry will be prohibited in a few years and it will be replaced by alternative methods based on cell and tissue culture. Many ingredients of cosmetic formulations are potentially causes of skin inflammation and sensibilization. Since cytotoxicity is known, among other factors, to trigger irritation, in an alternative model for evaluation of skin irritation, it can be considered also the precocious release of inflammatory mediators, i.e. cytokines, originating mainly from keratinocytes. In this in vitro study we have analysed some parameters directly or indirectly related to irritation/inflammation, in NCTC 2544 human keratinocytes during short-time exposure to some potential irritants cosmetic fragrances, included in the European Laws 2003/15/EEC. IIC50 was extrapolated by MTT and NRU viability indexes after exposure of cell ultures to Geraniol Limonene and Benzylic Alcohol for 1, 3 and 6h. NCTC cells were then exposed to sub-toxic doses of selected compounds and interleukin-1alpha (IL-1alpha) and leukaemia inhibitory factor (LIF) expressions were analysed as early proinflammatory cytokines. To our knowledge our findings demonstrated for the first time that NCTC cells synthesize and modulate LIF after exposure to selected irritating stimuli. Moreover, our results give evidence on LIF role as in vitro precocious endpoint for the assessment of the risk in cosmetic field, because its response under irritation stimuli is very quick and comparable to IL-1alpha.

Tenascin-X and leukemia inhibitory factor receptor are down-regulated in leiomyoma compared with normal myometrium

OBJECTIVE

Uterine leiomyomas are the most common tumor of the uterus. But the molecular causes of uterine leiomyoma remain unclear. We conducted the current investigation in order to elucidate the molecular mechanisms in the development of uterine leiomyoma.

METHODS

We employed a new and accurate reverse transcription-polymerase chain reaction (RT-PCR) method that involved annealing control primers (ACPs) to identify the genes that are differently expressed in uterine leiomyoma.

RESULTS

Using 120 ACPs, we identified and sequenced 14 differently expressed genes (DEGs) in uterine leiomyoma compared with normal myometrium. Basic Local Alignment Search Tool (BLAST) searches were performed to examine the known functions of these genes associated with uterine leiomyoma. We confirmed differently expressed patterns in more cases using the RT-PCR method. We also detected two novel genes, Tenascin-X and Leukemia Inhibitory Factor Receptor (LIFR), which had not yet been reported to have any functions associated with uterine leiomyoma. RT-PCR confirmation shows that both of these two genes are down-regulated in uterine leiomyoma.

CONCLUSION

Our results suggest that Tenascin-X and LIFR may play a role in the development of uterine leiomyoma. Although further studies are required to establish the precise mechanisms with which these genes are involved in the genesis of uterine leiomyoma, the present research is significant in that it is the first study which detects down-regulated novel genes in uterine leiomyoma using the ACP system.

Expression of Interleukin-11 and Interleukin-11 receptor α in human colorectal adenocarcinoma; Immunohistochemical analyses and correlation with clinicopathological factors

AIM: There is strong evidence that interleukin-11 (IL-11) is involved in the regulation of tumor progression, cellular growth and differentiation. Recently, interleukin-11 receptor (IL-11R) has been detected on some cancer cells. In this study, we investigated the expression of IL-11 and IL-11R in colorectal adenocarcinoma.

METHODS: To elucidate the involvement of IL-11 and IL-11Rα in human intestinal adenocarcinomas, we examined 115 cases of surgically resected human colonic adenocarcinoma and 11 cases of adenoma by immunohistochemistry and Western blotting.

RESULTS: Among 115 cases of adenocarcinoma, 100 cases (87.0%) showed positive staining in the cytoplasm of carcinoma cells for the IL-11, and 87 cases (75.6%) were positive for the IL-11Rα. Six cases (54.5%) and four cases (36.4%) of 11 adenomas were positive for IL-11 and IL-11Rα, respectively. The expression of IL-11Rα correlated with the histological differentiation (P = 0.033503), the depth of tumor invasion (P = 0.006395), Dukes’ classification (P = 0.015648) and lymphatic invasion (P = 0.003865). However, the expression of IL-11Rα was not correlated with the venous invasion and the presence of lymph node metastasis. The expression of IL-11 was not correlated with any clinicopathological factors. In Western blot analysis, two human colorectal carcinoma cell lines and four tissues of surgically resected human carcinoma expressed both IL-11 and IL-11Rα proteins.

CONCLUSION: IL-11 and IL-11Rα are highly expressed in human colorectal adenocarcinoma and the IL-11Rα expression is correlated with clinicopathological factors. These findings suggest that the expression of IL-11Rα is an important factor for the invasion of human colorectal adenocarcinoma.