Piwi interacting RNAs (piRNAs) constitute novel small non-coding RNA molecules of approximately 24–31 nucleotides in length that often bind to members of the piwi protein family to play regulatory roles. Recently, emerging evidence suggests that in addition to the mammalian germline, piRNAs are also expressed in a tissue-specific manner in a variety of human tissues and modulate key signaling pathways at the transcriptional or post-transcriptional level. In addition, a growing number of studies have shown that piRNA and PIWI proteins, which are abnormally expressed in various cancers, may serve as novel biomarkers and therapeutic targets for tumor diagnostics and treatment. However, the functions of piRNAs in cancer and their underlying mechanisms remain incompletely understood. In this review, we discuss current findings regarding piRNA biogenetic processes, functions, and emerging roles in cancer, providing new insights regarding the potential applications of piRNAs and piwi proteins in cancer diagnosis and clinical treatment.

As a novel class of endogenous RNAs, circRNAs, have a covalently closed continuous loop, with neither a 5’to 3’polarity, nor a polyadenylated tail. Numerous circRNAs have been characterized by abundance, stabilization, conservation, and exhibit tissue/developmental stage-specific expression. Furthermore, circRNAs play vital roles in tumorigenesis and metastasis, such as functioning as a ceRNA or miRNA sponge, interacting with protein and encoding protein. Increasing evidence has revealed that it potentially serves as a required novel biomarker for cancer diagnosis. This review summarized the latest research on circRNAs, including its classification and biogenesis, mechanism and functions, as well as circRNAs in different cancers, as a potential biomarker.

Purpose: Nanoparticle (NP)-mediated targeted delivery of therapeutic genes or siRNAs to tumors has potential advantages. In this study, hyaluronic acid (HA)-modified chitosan nanoparticles (CS NPs-HA) loaded with cyanine 3 (Cy3)-labeled siRNA (sCS NPs-HA) were prepared and characterized. Methods: Human non-small cell lung cancer (NSCLC) A549 cells expressing receptor CD44 and tumor-bearing mice were used to evaluate the cytotoxic and antitumor effects of sCS NPs-HA in vitro and in vivo. Results: The results showed that noncytotoxic CS NPs-HA of small size (100–200 nm) effectively delivered the Cy3-labeled siRNA to A549 cells via receptor CD44 and inhibited cell proliferation by downregulating the target gene BCL2. In vivo experiment results revealed that sCS NPs-HA directly delivered greater amounts of Cy3-labeled siRNA to the tumor sites, resulting in the inhibition of tumor growth by downregulating BCL2, as compared to unmodified NPs loaded with siRNA (sCS NPs) and to naked Cy3-labeled siRNA. Conclusion: The HA-modified NPs based on chitosan could serve as a promising carrier for siRNA delivery and targeted therapy for NSCLC expressing CD44.

There is currently no optimal scaffold for the transplantation of limbal stem cells (LSCs) to induce corneal reconstruction after corneal alkali burns. This study attempts to fabricate a novel in situ Alginate‐Chitosan hydrogel (ACH) for LSCs transplantation. Sodium alginate dialdehyde (SAD), a biological crosslinker, was prepared by periodate‐mediated sodium alginate oxidization. Carboxymethyl chitosan was rapidly crosslinked with SAD via Schiff's base formation between the available aldehyde and amino groups. The ACH is rapidly formed on the wound surface by self‐crosslinking without adding any chemical crosslinking component. Gelation time, transmittance, microscopic structure, equilibrium swelling, cytotoxicity, histocompatibility and degradability of the hydrogel were all examined. Rabbit primary LSCs were encapsulated in the hydrogel and transplanted to alkali burn wounds in vivo. Cornea reconstruction was evaluated by visual observation, slit lamp, histological analysis, and immunofluorescence staining. Results showed that the in situ hydrogel was highly transparent, gelated quickly, biocompatible, and had low cytotoxicity. LSCs cultured in vitro expressed the stem marker p63 but lacked the differentiated epithelial markers cytokeratin 3 and 12. Furthermore, the hydrogel encapsulating LSCs could be formed quickly on the alkali burn wound of the cornea and was shown to significantly improve epithelial reconstruction. Taken together, treatment with this novel in situ hydrogel‐mediated LSC transplantation system may serve as a rapid and effective method for corneal wound healing. © 2018 The Authors. Journal of Biomedical Materials Research Part A published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 742–754, 2019.

Identifying high specificity and sensitivity biomarkers has always been the focus of research in the field of non-invasive cancer diagnosis. Exosomes are extracellular vesicles with a lipid bilayer membrane that can be released by all types of cells, which contain a variety of proteins, lipids, and a variety of non-coding RNAs. Increasing research has shown that the lipid bilayer can effectively protect the nucleic acid in exosomes. In cancers, tumor cell-derived exosomal circRNAs can act on target cells or organs through the transport of exosomes, and then participate in the regulation of tumor development and metastasis. Since exosomes exist in various body fluids and circRNAs in exosomes exhibit high stability, exosomal circRNAs have the potential as biomarkers for early and minimally invasive cancer diagnosis and prognosis judgment. In this review, we summarized circRNAs and their biological roles in cancers, with the emerging value biomarkers in cancer diagnosis, disease judgment, and prognosis observation. In addition, we briefly compared the advantages of exosomal circRNAs as biomarkers and the current obstacles in the exosome isolation technology, shed light to the future development of this technology.