High Expression of Krüppel-like Factor 7 Indicates Unfavorable Clinical Outcomes in Patients with Lung Adenocarcinoma

Interactomic exploration of LRRC8A in volume-regulated anion channels

Ion channels are critical in enabling ion movement into and within cells and are important targets for pharmacological interventions in different human diseases. In addition to their ion transport abilities, ion channels interact with signalling and scaffolding proteins, which affects their function, cellular positioning, and links to intracellular signalling pathways. The study of "channelosomes" within cells has the potential to uncover their involvement in human diseases, although this field of research is still emerging. LRRC8A is the gene that encodes a crucial protein involved in the formation of volume-regulated anion channels (VRACs). Some studies suggest that LRRC8A could be a valuable prognostic tool in different types of cancer, serving as a biomarker for predicting patients' outcomes. LRRC8A expression levels might be linked to tumour progression, metastasis, and treatment response, although its implications in different cancer types can be varied. Here, publicly accessible databases of cancer patients were systematically analysed to determine if a correlation between VRAC channel expression and survival rate exists across distinct cancer types. Moreover, we re-evaluated the impact of LRRC8A on cellular proliferation and migration in colon cancer via HCT116 LRRC8A-KO cells, which is a current topic of debate in the literature. In addition, to investigate the role of LRRC8A in cellular signalling, we conducted biotin proximity-dependent identification (BioID) analysis, revealing a correlation between VRAC channels and cell-cell junctions, mechanisms that govern cellular calcium homeostasis, kinases, and GTPase signalling. Overall, this dataset improves our understanding of LRRC8A/VRAC and explores new research avenues while identifying promising therapeutic targets and promoting inventive methods for disease treatment.

Abnormal expression of Krüppel-like transcription factors and their potential values in lung cancer

Lung cancer still is one of the most common malignancy tumors in the world. However, the mechanisms of its occurrence and development have not been fully elucidated. Zinc finger protein family (ZNFs) is the largest transcription factor family in human genome. Recently, the more and more basic and clinical evidences have confirmed that ZNFs/Krüppel-like factors (KLFs) refer to a group of conserved zinc finger-containing transcription factors that are involved in lung cancer progression, with the functions of promotion, inhibition, dual roles and unknown classifications. Based on the recent literature, some of the oncogenic KLFs are promising molecular biomarkers for diagnosis, prognosis or therapeutic targets of lung cancer. Interestingly, a novel computational approach has been proposed by using machine learning on features calculated from primary sequences, the XGBoost-based model with accuracy of 96.4 % is efficient in identifying KLF proteins. This paper reviews the recent some progresses of the oncogenic KLFs with their potential values for diagnosis, prognosis and molecular target in lung cancer.

The role of KLF transcription factor in the regulation of cancer progression

Kruppel-like factors (KLFs) are a family of zinc finger transcription factors that have been found to play an essential role in the development of various human tissues, including epithelial, teeth, and nerves. In addition to regulating normal physiological processes, KLFs have been implicated in promoting the onset of several cancers, such as gastric cancer, lung cancer, breast cancer, liver cancer, and colon cancer. To inhibit cancer progression, various existing medicines have been used to modulate the expression of KLFs, and anti-microRNA treatments have also emerged as a potential strategy for many cancers. Investigating the possibility of targeting KLFs in cancer therapy is urgently needed, as the roles of KLFs in cancer have not received enough attention in recent years. This review summarizes the factors that regulate KLF expression and function at both the transcriptional and posttranscriptional levels, which could aid in understanding the mechanisms of KLFs in cancer progression. We hope that this review will contribute to the development of more effective anti-cancer medicines targeting KLFs in the future.

Stress-inducible IL-6 is regulated by KLF7 in brown adipocytes

Stress-inducible interleukin 6 (IL-6) is generated in brown adipocytes via beta-3 adrenergic receptor (ADRB3) signaling, which is necessary in stress hyperglycemia, the kind of metabolic adaptation enabling "fight or flight" response by means of liver gluconeogenesis. Nevertheless, the mechanism of ADRB3 signaling mediates IL-6 in brown adipocytes remains unclear. As a result, it is critical to understand how brown adipocytes produce IL-6 via ADRB3 signaling. We found that the ADRB3 agonist and cold stimulation promoted the expression of KLF7 and IL-6 in brown adipocytes of mice. In parallel to these results in vivo, treatment with ADRB3 agonist promoted the expression of KLF7 and the release of IL-6 in primary brown adipocytes of mice. Notably, we discovered that KLF7 positively controls the expression of IL-6 and downregulated KLF7 largely blunted ADRB3 agonist induced IL-6 expressions in brown adipocytes. Our findings suggest that KLF7 is required for the generation of IL-6 when ADRB3 signaling is activated in brown adipocytes.

Krüppel-like factors in tumors: Key regulators and therapeutic avenues

Krüppel-like factors (KLFs) are a group of DNA-binding transcriptional regulators with multiple essential functions in various cellular processes, including proliferation, migration, inflammation, and angiogenesis. The aberrant expression of KLFs is often found in tumor tissues and is essential for tumor development. At the molecular level, KLFs regulate multiple signaling pathways and mediate crosstalk among them. Some KLFs may also be molecular switches for specific biological signals, driving their transition from tumor suppressors to promoters. At the histological level, the abnormal expression of KLFs is closely associated with tumor cell stemness, proliferation, apoptosis, and alterations in the tumor microenvironment. Notably, the role of each KLF in tumors varies according to tumor type and different stages of tumor development rather than being invariant. In this review, we focus on the advances in the molecular biology of KLFs, particularly the regulations of several classical signaling pathways by these factors, and the critical role of KLFs in tumor development. We also highlight their strong potential as molecular targets in tumor therapy and suggest potential directions for clinical translational research.

Expression and Clinical Significance of Serum Krüppel-Like Factor 7 (KLF7) in NSCLC Patients

Nonsmall cell lung cancer (NSCLC) is a serious threat to the life and health of patients with high incidence rate and mortality. The present research was to assess the relationship between the serum Krüppel-like factor 7 (KLF7) level and the recurrence and metastasis of NSCLC patients. 150 patients with NSCLC treated by thoracoscopic radical resection of lung cancer in our hospital from January 2016 to February 2017 were selected. As the control group, 148 healthy people who went to the hospital for physical examination in the same period were screened. The expression levels of serum KLF7 in the observation group and the control group were compared and analyzed. According to the level of KLF7 expression, the patients in the observation group were divided into KLF7 high expression group (≥258.6 ng/L, n =75) and KLF7 low expression group (<258.6 ng/L, n =75). The 3-year recurrence and metastasis rate of patients in each group was compared and analyzed. It was found the concentration of serum KLF7 in peripheral blood of NSCLC (2.25 ± 0.65) ng/ml was significantly higher than that in healthy population (1.42 ± 0.38) ng/ml (P < 0.05). The expression level of serum KLF7 was not related to gender, age, smoking history, and tumor diameter of NSCLC patients (P > 0.05), but related to the degree of differentiation and TNM stage of NSCLC patients (P < 0.05). Univariate analysis showed that the degree of differentiation, TNM stage, and KLF7 were significantly correlated with 3-year recurrence and metastasis of NSCLC patients (P < 0.05). Cox regression analysis showed that low degree of differentiation, TNM stage IIIa, and KLF7 were independent risk factors for recurrence and metastasis in NSCLC patients in 3 years (P < 0.05). Taken together, the expression level of serum KLF7 in patients with NSCLC is significantly increased, which is an independent risk factor for recurrence and metastasis in 3 years, and is worthy of clinical application.

Expression and Prognosis Value of the KLF Family Members in Colorectal Cancer

Krüppel-like factors (KLFs) are some kind of transcriptional regulator that regulates a broad range of cellular functions and has been linked to the development of certain malignancies. KLF expression patterns and prognostic values in colorectal cancer (CRC) have, however, been investigated rarely. To investigate the differential expression, predictive value, and gene mutations of KLFs in CRC patients, we used various online analytic tools, including ONCOMINE, TCGA, cBioPortal, and the TIMER database. KLF2-6, KLF8-10, KLF12-15, and KLF17 mRNA expression levels were dramatically downregulated in CRC tissues, but KLF1, KLF7, and KLF16 mRNA expression levels were significantly elevated in CRC tissues. According to the findings of Cox regression analysis, upregulation of KLF3, KLF5, and KLF6 and downregulation of KLF15 were linked with a better prognosis in CRC. For functional enrichment, our findings revealed that KLF members are involved in a variety of cancer-related biological processes. In colon cancer and rectal cancer, KLFs were also shown to be associated with a variety of immune cells. The findings of this research reveal that KLF family members' mRNA expression levels are possible prognostic indicators for patients with CRC.

Genome-Wide Enhancer Analysis Reveals the Role of AP-1 Transcription Factor in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers in the world, but its epigenomic features have not been determined. Here, we studied the chromatin landscape of active enhancers of HNSCC head tumor tissues by performing H3K27ac and H3K4me1 ChIP-Seq with a Tgfbr1/Pten double conditional knockout HNSCC mouse model. We identified 1,248 gain variant enhancer loci (VELs) and 2,188 lost VELs, as well as 153 gain variant super enhancer loci (VSELs) and 234 lost VSELs. Potentially involved transcription factors were predicted with motif analysis, and we identified AP-1 as one of the critical oncogenic transcription factors in HNSCC and many other types of cancer. Combining transcriptomic and epigenomic data, our analysis also showed that AP-1 and histone modifications coordinately regulate target gene expression in HNSCC. In conclusion, our study provides important epigenomic information for enhancer studies in HNSCC and reveals new mechanism for AP-1 regulating HNSCC.

GNA14 stimulation of KLF7 promotes malignant growth of endometrial cancer through upregulation of HAS2

BACKGROUND

Endometrial cancer (UCEC) is one of the most common gynecological malignancies. We previously found that overexpression of G protein α subunit 14 (GNA14) promoted UCEC growth. Krüppel-like factor 7 (KLF7) acts as an oncogene in various cancer types, whereas the connection between GNA14 and KLF7 in UCEC is unclear. We herein explored the involvement of GNA14/KLF7 in UCEC development.

METHODS

Clinical relevance of GNA14, KLF7 and HAS2 in UCEC was analyzed from TCGA and by immunohistochemical staining. Knockdown and overexpression of indicated genes were conducted by transfecting the cells with siRNAs and lentivirus, respectively. mRNA and protein expression was detected by qRT-PCR and Western blot. CCK8, colony formation, cell cycle, apoptosis, transwell and wound healing were performed to check cell biology function in vitro. Tumor growth in nude mice was conducted to check in vivo function. RNA sequencing was used to determine dys-regulated genes.

RESULTS

We demonstrated that GNA14 stimulated the expression of KLF7 in UCEC cells. There was a positive correlation between GNA14 and KLF7 in normal and UCEC tissues. In vitro, KLF7 promoted cell proliferation, colony formation, cell cycle progression, and migration of UCEC cells. Apoptosis was inhibited by KLF7. Xenografted tumorigenesis of UCEC cells was suppressed by KLF7 knockdown. Furthermore, RNA sequencing results showed that KLF7 regulated the expression of a large amount of genes, among which hyaluronan synthase 2 (HAS2) was downregulated in KLF7 knockdown cells. Based on TCGA database and immunoblotting assays, KLF7 positively regulated HAS2 in UCEC cells and tissues. Lastly, knockdown of HAS2 reversed the oncogenic role of KLF7 on UCEC cell proliferation, migration, and xenografted tumor development.

CONCLUSION

Taken together, we reveal that GNA14/KLF7/HAS2 signaling cascade exerts tumor promoting function during UCEC development.

Transcriptional control of chicken KLF7 promoter in preadipocytes

Krüppel-like factor 7 (KLF7) has been reported to inhibit adipogenesis and regulate the development of the nervous system. However, transcription regulation of KLF7 remains poorly understood. In the current study, a 2196-bp-long 5'-flanking sequence of chicken KLF7 (-2286 bp to -91 bp, upstream of the translation start site) was studied for promoter activity, and there was a remarkable promoter activity in this sequence (P<0.05). The 5'-truncated mutation analysis showed that a minimal promoter was on the sequence from -241 bp to -91 bp. In addition, GATA2 overexpression facilitated the promoter activity of pGL3-KLF7(-2286/-91), pGL3-KLF7(-1215/-91), pGL3-KLF7(-521/-91), and pGL3-KLF7(-241/-91), and GATA3 overexpression inhibited the promoter activity of pGL3-KLF7(-1845/-91), pGL3-KLF7(-1215/-91), pGL3-KLF7(-521/-91), and pGL3-KLF7(-241/-91) in chicken preadipocytes (P<0.05). Knockdown of GATA2 expression inhibited the promoter activity of pGL3-KLF7(-1215/-91) and pGL3-KLF7(-241/-91), and knockdown of GATA3 expression facilitated the promoter activity of pGL3-KLF7(-521/-91) and pGL3-KLF7(-241/-91) (P<0.05). Additionally, overexpression and knockdown analyses showed that GATA3 inhibited KLF7 mRNA expression (P<0.05), and both overexpression and knockdown of GATA2 resulted in the downregulation of KLF7 mRNA expression in chicken preadipocytes (P<0.05). Western blot analysis in chicken preadipocytes showed that GATA2 facilitated KLF7 expression and GATA3 inhibited KLF7 expression. Mutation analysis showed that the motif of 'GGATCTATCA' (-107 bp/-98 bp) might be a cis-regulation element, which is involved in the KLF7 expression regulation by GATA3 in chicken preadipocytes. These results provided some details of KLF7 transcription regulation in chicken adipose tissue.

KLF7: a new candidate biomarker and therapeutic target for high-grade serous ovarian cancer

BACKGROUND

In spite of great progress in the surgical and clinical management, until now no significant improvement in overall survival of High-Grade Serous Ovarian Cancer (HGSOC) patients has been achieved. Important aspects for disease control remain unresolved, including unclear pathogenesis, high heterogeneity and relapse resistance after chemotherapy. Therefore, further research on molecular mechanisms involved in cancer progression are needed to find new targets for disease management. The Krüppel-like factors (KLFs) are a family of transcriptional regulators controlling several basic cellular processes, including proliferation, differentiation and migration. They have been shown to play a role in various cancer-relevant processes, in a context-dependent way.

METHODS

To investigate a possible role of KLF family members as prognostic biomarkers, we carried out a bioinformatic meta-analysis of ovarian transcriptome datasets in different cohorts of late-stage HGSOC patients. In vitro cellular models of HGSOC were used for functional studies exploring the role of KLF7 in disease development and progression. Finally, molecular modelling and virtual screening were performed to identify putative KLF7 inhibitors.

RESULTS

Bioinformatic analysis highlighted KLF7 as the most significant prognostic gene, among the 17 family members. Univariate and multivariate analyses identified KLF7 as an unfavourable prognostic marker for overall survival in late-stage TCGA-OV and GSE26712 HGSOC cohorts. Functional in vitro studies demonstrated that KLF7 can play a role as oncogene, driving tumour growth and dissemination. Mechanistic targets of KLF7 included genes involved in epithelial to mesenchymal transition, and in maintaining pluripotency and self-renewal characteristics of cancer stem cells. Finally, in silico analysis provided reliable information for drug-target interaction prediction.

CONCLUSIONS

Results from the present study provide the first evidence for an oncogenic role of KLF7 in HGSOC, suggesting it as a promising prognostic marker and therapeutic target.

DNA methylation of CpG sites in the chicken KLF7 promoter and Exon 2 in association with mRNA expression in abdominal adipose tissue and blood metabolic indicators

BACKGROUND

Our previous study found that chicken KLF7 was an important regulator in formation of adipose tissue. In the present study, we analyzed the association for DNA methylation in chicken KLF7 with its transcripts of abdominal adipose tissue and blood metabolic indicators.

RESULTS

The KLF7 transcripts of the adipose tissue of Chinese yellow broilers were associated with age (F = 6.67, P = 0.0035). In addition, the KLF7 transcripts were negatively correlated with blood glucose levels (r = - 0.61841, P = 0.0140). The DNA methylation levels of 26 CpG loci in the chicken KLF7 promoter and Exon 2 were studied by Sequenom MassArray. A total of 22 valid datasets were obtained. None of them was significantly different in relation to age (P > 0.05). However, the DNA methylation levels in the promoter were lower than those in Exon 2 (T = 40.74, P < 0.01). Correlation analysis showed that the DNA methylation levels of PCpG6 and E2CpG9 were significantly correlated with KLF7 transcripts and blood high-density lipoprotein levels, respectively, and many CpG loci were correlated with each other (P < 0.05). The methylation data were subjected to principal component analysis and factor analysis. The six principal components (z1-z6) were extracted and named Factors 1-6, respectively. Factor analysis showed that Factor 1 had a higher load on the loci in the promoter, and Factors 2-6 loaded highly on quite different loci in Exon 2. Correlation analysis showed that only z1 was significantly correlated to KLF7 transcripts (P < 0.05). In addition, an established regression equation between z1 and KLF7 transcripts was built, and the contribution of z1 to the variation on KLF7 transcripts was 34.29%.

CONCLUSIONS

In conclusion, the KLF7 transcripts of chicken abdominal adipose tissue might be inhibited by DNA methylation in the promoter, and it might be related to the DNA methylation level of PCpG6.

The Importance of Breast Adipose Tissue in Breast Cancer

Adipose tissue is a complex endocrine organ, with a role in obesity and cancer. Adipose tissue is generally linked to excessive body fat, and it is well known that the female breast is rich in adipose tissue. Hence, one can wonder: what is the role of adipose tissue in the breast and why is it required? Adipose tissue as an organ consists of adipocytes, an extracellular matrix (ECM) and immune cells, with a significant role in the dynamics of breast changes throughout the life span of a female breast from puberty, pregnancy, lactation and involution. In this review, we will discuss the importance of breast adipose tissue in breast development and its involvement in breast changes happening during pregnancy, lactation and involution. We will focus on understanding the biology of breast adipose tissue, with an overview on its involvement in the various steps of breast cancer development and progression. The interaction between the breast adipose tissue surrounding cancer cells and vice-versa modifies the tumor microenvironment in favor of cancer. Understanding this mutual interaction and the role of breast adipose tissue in the tumor microenvironment could potentially raise the possibility of overcoming breast adipose tissue mediated resistance to therapies and finding novel candidates to target breast cancer.

Elevated KLF7 levels may serve as a prognostic signature and might contribute to progression of squamous carcinoma

Global efforts have been undertaken to define the genome-wide distribution of epigenetic markers in cancerous tissues, which provide an invaluable opportunity to understand cancer biology and identify predictive signatures. Several studies have focused on the gene expression patterns of squamous carcinoma to identify tumor subtypes and find prognostic and therapeutic targets because squamous carcinoma genomes showed high instability. However, the number of reliable reports referring prognostic significance of genes and their role in squamous carcinoma is still quite limited. Krüppel-like factor 7 (KLF7) is a transcription factor that is widely expressed in numerous human tissues at low levels. Members of the KLF family have established roles in tumor cell fate, stress response, cell survival and the tumor-initiating properties of cancer stem-like cells. Hence to investigate whether KFL7 expression from cancer tissue holds promise as a prognostic and/or therapeutic target, we analyzed gene expression profiles from squamous carcinoma and surgical margin tissues in The Cancer Genome Atlas. We identified significant up-regulation of KLF7 in squamous carcinoma, which was confirmed by immunohistochemical staining. Elevated KLF7 expression was associated with poor squamous carcinoma prognosis before and after correcting for confounding factors by multivariate Cox regression analysis. Several pathways, such as Neurotrophin and GnRH pathways, were activated in KLF7-up-regulated squamous carcinoma samples through Gene Set Enrichment Analysis. In conclusion, we consolidate the potential role(s) of KLF7 in squamous carcinoma carcinogenesis from The Cancer Genome Atlas surgical margin tissue, offering insights into expression signatures that are potentially useful for prognosis modalities.

MicroRNA‑103 modulates tumor progression by targeting KLF7 in non‑small cell lung cancer

Numerous studies have identified that microRNAs (miRs) play a crucial role in the tumorigenesis of non-small cell lung cancer (NSCLC). However, to the best of our knowledge, the physiological function of miR-103 in NSCLC is not fully understood. Experiments in the present study revealed that miR-103 expression was increased in NSCLC cell lines. In addition, a series of methods, including MTT, colony formation, 5-ethynyl-2′-deoxyuridine, Transwell, wound healing, flow cytometric, reverse transcription-quantitative PCR and western blot assays, were performed, which revealed that overexpression of miR-103 enhanced cell growth, migration, invasion and epithelial-mesenchymal transition (EMT), and suppressed apoptosis of A549 and H1299 cells. Additionally, a dual-luciferase reporter assay indicated that miR-103 directly targets the 3′-untranslated region of Kruppel-like factor 7 (KLF7), and KLF7 expression was negatively regulated by miR-103 expression. Furthermore, the present findings demonstrated that miR-103 promoted EMT via regulating the Wnt/β-catenin signaling pathway in NSCLC. Collectively, the current results demonstrated that miR-103 serves a tumorigenesis role in NSCLC development by targeting KLF7, at least partly via the Wnt/β-catenin signaling pathway. Consequently, these findings indicated that miR-103/KLF7/Wnt/β-catenin may provide a novel insight into underlying biomarkers for improving the diagnosis and treatment of NSCLC.