  Citation: Matboli, M.; Hassan, M.K.; Ali, M.A.; Mansour, M.T.; Elsayed, W.; Atteya, R.; Aly, H.S.; Meteini, M.E.; Elghazaly, H.; El-Khamisy, S.; et al. Impact of circ-0000221 in the Pathogenesis of Hepatocellular via Modulation of miR-661–PTPN11 mRNA Axis. Pharmaceutics 2022, 14, 138. https://doi.org/10.3390/ pharmaceutics14010138 Academic Editors: Dan Peer, Philippe Barthélémy and Tina Kauss Received: 24 November 2021 Accepted: 5 January 2022 Published: 6 January 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). pharmaceutics Article Impact of circ-0000221 in the Pathogenesis of Hepatocellular via Modulation of miR-661–PTPN11 mRNA Axis Marwa Matboli 1, * ,† , Mohmed Kamal Hassan 2,3,† , Mahmoud A. Ali 4 , Mohamed Tarek Mansour 4 , Waheba Elsayed 2 , Reham Atteya 2 , Hebatallah Said Aly 1 , Mahmoud El Meteini 5 , Hesham Elghazaly 6 , Sherif El-Khamisy 7,8,† and Sara H. A. Agwa 9, * 1 Medical Biochemistry and Molecular Biology Department, Faculty of Medicine, Ain Shams University, Abbassia, Cairo 11381, Egypt; hebatallahsaid@med.asu.edu.eg 2 Center for Genomics, Helmy Institute for Medical Sciences, Zewail City for Science and Technology, Giza 12578, Egypt; mfarah@zewailcity.edu.eg (M.K.H.); p-walsayed@zewailcity.edu.eg (W.E.); p-rattaeya@zewailcity.edu.eg (R.A.) 3 Biotechnology Program, Biology Division, Zoology Department, Faculty of Science, Port Said University, Port Said 42526, Egypt 4 Department of Biomedical Research, Armed Forces College of Medicine (AFCM), Cairo 11774, Egypt; mahmoudali@gmail.com (M.A.A.); habibaabdelnaser70@gmail.com or mohammadtarek459@gmail.com (M.T.M.) 5 Department of General Surgery, The School of Medicine, University of Ain Shams, Abbassia, Cairo 11382, Egypt; mahmoud_elmeteini@med.asu.edu.eg 6 Oncology Department, Faculty of Medicine, Medical Ain Shams Research Institute (MASRI), Ain Shams University, Cairo 11382, Egypt; heshamelghazaly@med.asu.edu.eg 7 The Healthy Lifespan Institute, The Institute of Neuroscience, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK; s.el-khamisy@sheffield.ac.uk 8 The Institute of Cancer Therapeutics, West Yorkshire BD7 1DP, UK 9 Clinical pathology and Molecular Genomics Unit, Faculty of Medicine, Medical Ain Shams Research Institute (MASRI), Ain Shams University, Cairo 11382, Egypt * Correspondence: DrMarwa_Matboly@med.asu.edu.eg (M.M.); sara.h.agwa@med.asu.edu.eg (S.H.A.A.) † These authors contributed equally to this work. Abstract: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death in Egypt. A deep understanding of the molecular events occurring in HCC can facilitate the development of novel diagnostic and/or therapeutic approaches. In the present study, we describe a novel axis of hsa-circ-0000221–miR-661–PTPN11 mRNA proposed by in silico and in vitro analysis and its role in HCC pathogenesis. We observe a reduction in the expression levels of hsa-circ-0000221 and PTPN11 mRNA in HCC patients’ sera tested compared with control subjects. The reduction occurs with a concomitant increase in the expression of miR-661. Furthermore, the introduction of exogenous hsa-circ-0000221 into Hep-G2 or SNU449 cell lines results in detectable decrease in cellular viability and an increase in apoptotic manifestations that is associated with G1 accumulation and CCDN1 overexpression. Altogether, these findings indicate the tumor-suppressive role of hsa-circ-0000221 in HCC, which acts through miR-661 inhibition, along with a subsequent PTPN11 mRNA increase, where PTPN11 is known to inhibit cell proliferation in many forms of cancer. Our study encourages further investigation of the role of circRNAs in cancer and their potential use as molecular biomarkers. Keywords: hepatocellular carcinoma; hsa-circ-0000221; miR-661; PTPN11 1. Introduction Hepatocellular carcinoma (HCC) is the most common type of liver cancer and one of the major causes of cancer-related death worldwide [1]). Early diagnosis of HCC is possible, and radical surgeries are a common treatment modality with mostly favorable prognostic outcomes [2]. However, many patients with HCC are missed with the current diagnostic standards and, therefore, lose the operation opportunity. To improve the therapeutic Pharmaceutics 2022, 14, 138. https://doi.org/10.3390/pharmaceutics14010138 https://www.mdpi.com/journal/pharmaceutics