Long non‐coding RNA LINC00673 silencing inhibits proliferation and drug resistance of prostate cancer cells via decreasing KLF4 promoter methylation

Abstract

| INTRODUC TI ONAs a non-skin tumour accompanied by variable natural history, prostate cancer is a highly prevalent malignancy and represents one of the leading causes of cancer-related deaths in the male populace. 1,2 Risk factors responsible for prostate cancer comprise smoking, alcohol consumption and levels of male androgens. 3 Paclitaxel is widely regarded as an essential important drug for prostate cancer treatment; however, paclitaxel resistance ensues in many prostate cancer patients, which highlights the significance of developing strategies AbstractProstate cancer is one of the major causes of cancer-related mortality in men across the world. Recently, long non-coding RNAs (lncRNAs) and Kruppel-like factor 4 (KLF4) have been reported to participate in the biology of multiple cancers including prostate cancer. Here, this study aimed to explore the possible role of LINC00673 in prostate cancer via KLF4 gene promoter methylation. Microarray-based gene expression profiling of prostate cancer was employed to identify differentially expressed lncRNAs and genes, after which the expression of LINC00673 and KLF4 in prostate cancer tissues was determined using RT-qPCR. Next, the relationship between LINC00673 and KLF4 was evaluated using in silico analysis. Further, the effect of LINC00673 and KLF4 on cell proliferation and drug resistance of transfected cells was examined with gain-and loss-of-function experimentation. It was found that LINC00673 was highly expressed, while KLF4 was poorly expressed in prostate cancer tissues. Additionally, LINC00673 could bind to KLF4 gene promoter region and recruit methyltransferase to the KLF4 gene promoter region. Moreover, LINC00673silencing was demonstrated to reduce methylation of the KLF4 gene promoter to elevate the expression of KLF4, thus suppressing the proliferation and drug resistance of prostate cancer cells. In summary, LINC00673 silencing could drive demethylation of the KLF4 gene promoter and thus inhibit the proliferation and drug resistance of prostate cancer cells, suggesting that silencing of LINC00673 and elevation of KLF4 could serve as tumour suppressors in prostate cancer.

Prediction of Prognosis in Patients with Prostate Cancer by DNA Methylation Classification

“…As a new tumor suppressor gene, KLF4 has a hypermethylated promoter sequence, and its gene expression is downregulated in prostate cancer, which promotes tumor proliferation and drug resistance. Downregulation of KLF4 or hypermethylation of KLF4 gene promoters can be considered markers for predicting the early recurrence of cancer [22,23]. GSTP1 is functionally inactivated by promoter methylation, which increases the sensitivity to oxidative stress and increases the risk of prostate cancer progression [24].…”

lncRNA and Mechanisms of Drug Resistance in Cancers of the Genitourinary System

“…In cancer, KLF4 function is frequently lost due to hypermethylation of CpG islands in the promotor region [159]. Suppression of LINC00673 led to improved chemosensitivity through increased KLF4 activity in both in vitro and in vivo experimental models and additionally reduced proliferation in PCa cell lines [38]. This is in line with results in gastric cancer, where epigenetic suppression of KLF4 through LINC00673 was associated with poor OS (HR = 2.989, 95%CI 1.126-5.178, p = 0.001) [160].…”

Recent Discoveries on the Involvement of Krüppel-Like Factor 4 in the Most Common Cancer Types

“…Some reports indicate that KLF4 promotes prostate cancer growth [ 94 , 95 ] while other reports claim the opposite [ 96 , 97 , 98 ]. Some research teams discovered that KLF4 is upregulated in prostate tumor samples [ 95 ] while other reports claim that the levels of KLF4 are in fact reduced in prostate cancer [ 96 , 97 , 98 ]. In one study, KLF4 was detected primarily in the cytoplasm of non-tumor prostate tissues, and it was suggested that subcellular localization of KLF4 may be an important factor in prostate cancer [ 98 ].…”

“…In prostate cancer this feedback loop is dysregulated due to the disrupted miR-7 processing, which leads to the overexpression of KLF4, maintaining stemness of prostate cancer stem cells to promote tumor growth [ 94 ]. The expression of KLF4 is negatively regulated by lncRNA LINC00673 [ 96 ]. LINC00673 binds to the KLF4 promoter and recruits DNMT1, DNMT3a and DNMT3b.…”

“…LINC00673 binds to the KLF4 promoter and recruits DNMT1, DNMT3a and DNMT3b. This results in increased methylation status of the KLF4 promoter and reduced KLF4 expression [ 96 ]. Lysine (K)-specific methyltransferase 2D (KMT2D) is yet another epigenetic modifier that negatively regulates the expression of KLF4 in prostate cancer [ 103 ].…”