circRNA/miRNA Networks Regulate KLF4 in Tumor Development.

Background/Objectives: Krüppel-like factor 4 (KLF4) emerged as an epigenetically regulated gene in a variety of settings, including cell reprogramming and malignant cell proliferation. The aim of the present manuscript is to explore the relationship described in recent years between circular RNAs, miRNAs, and KLF4. These have been shown to be involved in cancers having diverse histological origins, including some of the most prevalent and deadly tumors for the human population. Expression and protein levels of this transcription factor correlate with invasiveness and prognosis in a context- and tissue-specific fashion. Methods: The literature was obtained through two main PubMed queries. The first is "miRNA and KLF4 and cancer" and is limited to the last 5 years. The second is "circRNA and KLF4", which yielded publications between 2013 and 2024. The oncological publications were selected. Results: A number of circRNA/miRNA axes that regulate the downstream transcription factor KLF4 emerged in the last few years. circRNAs act as sponges for miRNAs and synergize with KLF4, which can function as either a tumor promoter or suppressor in different tumors. Conclusions: The axes represented by circRNA/miRNA/KLF4 emerged as a new layer of epigenetic regulation. These RNA-based modulators explain the complex regulation of this transcription factor and open the way to new therapeutic targeting possibilities.