biomolecules Review Biomedical Relevance of Novel Anticancer Peptides in the Sensitive Treatment of Cancer Olalekan Olanrewaju Bakare 1, * , Arun Gokul 2 , Ruomou Wu 1 , Lee-Ann Niekerk 1 , Ashwil Klein 3 and Marshall Keyster 1, *   Citation: Bakare, O.O.; Gokul, A.; Wu, R.; Niekerk, L.-A.; Klein, A.; Keyster, M. Biomedical Relevance of Novel Anticancer Peptides in the Sensitive Treatment of Cancer. Biomolecules 2021, 11, 1120. https:// doi.org/10.3390/biom11081120 Academic Editors: Melanie R. Power Coombs and David W. Hoskin Received: 26 June 2021 Accepted: 24 July 2021 Published: 29 July 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 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/). 1 Environmental Biotechnology Laboratory, Department of Biotechnology, University of the Western Cape, Bellville 7535, South Africa; 3056605@myuwc.ac.za (R.W.); 3255882@myuwc.ac.za (L.-A.N.) 2 Department of Plant Sciences, Qwaqwa Campus, University of the Free State, Phuthaditjhaba 9866, South Africa; Gokula@ufs.ac.za 3 Plant Omics Laboratory, Department of Biotechnology, University of the Western Cape, Bellville 7535, South Africa; aklein@uwc.ac.za * Correspondence: lekanbakare77@gmail.com (O.O.B.); mKeyster@uwc.ac.za (M.K.); Tel.: +27-603112776 (O.O.B.); +27-9592214 (M.K.) Abstract: The global increase in cancer mortality and economic losses necessitates the cautious quest for therapeutic agents with compensatory advantages over conventional therapies. Anticancer peptides (ACPs) are a subset of host defense peptides, also known as antimicrobial peptides, which have emerged as therapeutic and diagnostic candidates due to several compensatory advantages over the non-specificity of the current treatment regimens. This review aimed to highlight the ravaging incidence of cancer, the use of ACPs in cancer treatment with their mechanisms, ACP discovery and delivery methods, and the limitations for their use. This would create awareness for identifying more ACPs with better specificity, accuracy and sensitivity towards the disease. It would also promote their efficacious utilization in biotechnology, medical sciences and molecular biology to ease the severity of the disease and enable the patients living with these conditions to develop an accommodating lifestyle. Keywords: anticancer peptides; apoptosis; cancer; cytolysis; host-defense peptides; peptide delivery 1. Introduction Cancer is used synonymously to mean either malignant tumors or neoplasms and refers to a group of diseases that affect any part of the human body [1]. According to the World Health Organization (WHO), it is the leading cause of global mortality, accounting for about 20 million deaths in 2020, in which the most common causes of death include lung (1.80 million), colon and rectum (935,000), liver (830,000), stomach (769,000) and breast (685,000) [2]. It occurs through the rapid formation of abnormal cells that develop uncontrollably to invade the surrounding body parts and organs through the process of metastasis, the primary cause of death from cancer [3]. Cancer affects all age groups, but the incidence of cancer rises with age due to the build-up risk of specific cancers that increases with age, coupled with the fact that the capacity for cellular amelioration mechanisms becomes less effective with age [4]. The causes of cancer have been linked to a series of interactions between an indi- vidual’s genetic factors and the three categories of external agents [5]. These external agents include biological carcinogens through infections from some parasites, viruses and bacteria [6]; physical carcinogens through the interaction with ultraviolet and ionizing radiation [7]; and chemical carcinogens through exposure to asbestos, tobacco smoke, water contaminants, such as arsenic, and food contaminants such as aflatoxins [8]. Approximately thirteen percent of cancers diagnosed in 2018, for instance, were caused by carcinogenic infections such as hepatitis B virus, hepatitis C virus, Epstein Barr virus, human papil- lomavirus (HPV) and Helicobacter pylori [9]. Particularly, the risk of liver and cervical Biomolecules 2021, 11, 1120. https://doi.org/10.3390/biom11081120 https://www.mdpi.com/journal/biomolecules