Peptide SA12 inhibits proliferation of breast cancer cell lines MCF-7 and MDA-MB-231 through G0/G1 phase cell cycle arrest

Anticancer peptides mechanisms, simple and complex

Peptide therapy has started since 1920s with the advent of insulin application, and now it has emerged as a new approach in treatment of diseases including cancer. Using anti-cancer peptides (ACPs) is a promising way of cancer therapy as ACPs are continuing to be approved and arrived at major pharmaceutical markets. Traditional cancer treatments face different problems like intensive adverse effects to patient's body, cell resistance to conventional chemical drugs and in some worse cases the occurrence of cell multidrug resistance (MDR) of cancerous tissues against chemotherapy. On the other hand, there are some benefits conceived for peptides usage in treatment of diseases specifically cancer, as these compounds present favorable characteristics such as smaller size, high activity, low immunogenicity, good biocompatibility in vivo, convenient and rapid way of synthesis, amenable to sequence modification and revision and there is no limitation for the type of cargo they carry. It is possible to achieve an optimum molecular and functional structure of peptides based on previous experience and bank of peptide motif data which may result in novel peptide design. Bioactive peptides are able to form pores in cell membrane and induce necrosis or apoptosis of abnormal cells. Moreover, recent researches have focused on the tumor recognizing peptide motifs with the ability to permeate to cancerous cells with the aim of cancer treatment at earlier stages. In this strategy the most important factors for addressing cancer are choosing peptides with easy accessibility to tumor cell without cytotoxicity effect towards normal cells. The peptides must also meet acceptable pharmacokinetic requirements. In this review, the characteristics of peptides and cancer cells are discussed. The various mechanisms of peptides' action proposed against cancer cells make the next part of discussion. It will be followed by giving information on peptides application, various methods of peptide designing along with introducing various databases. Future aspects of peptides for employing in area of cancer treatment come as conclusion at the end.

Anti-tumor peptide SA12 inhibits metastasis of MDA-MB-231 and MCF-7 breast cancer cells via increasing expression of the tumor metastasis suppressor genes, CDH1, nm23-H1 and BRMS1

In recent years, there has been progress in the treatment of breast cancer; however, the prognosis is still poor due to recurrence and metastasis following conventional treatment. The anti-tumor peptide SA12 has been demonstrated to inhibit proliferation and arrest the cell cycle in MDA-MB-231 and MCF-7 breast cancer cells. In the present study, whether SA12 was able to inhibit the metastasis of breast cancer cells was investigated. Wound healing and Transwell assays were used to investigate the inhibition of SA12 on cell migration while, reverse transcription-quantitative PCR and western blot assays were used to identify the mechanism of action behind the effects of SA12 on cell migration. Results from the wound healing and Transwell assays revealed that SA12 significantly inhibited the migration of MDA-MB-231 and MCF-7 breast cancer cells following treatment with 100 µM SA12. Compared with that in the controls, the mRNA expression levels of cadherin 1 (CDH1), non-metastasis 23-H1 (nm23-H1) and breast cancer metastasis suppressor 1 (BRMS1) were increased in MDA-MB-231 and MCF-7 cells following treatment with 100 µM SA12. Furthermore, the protein expression levels of E-cadherin, NM23A and BRMS1 were also increased in MDA-MB-231 cells and MCF-7 cells following treatment with 100 µM SA12. In conclusion, SA12 inhibited the migration of MDA-MB-231 and MCF-7 breast cancer cells and enhanced the expression of the tumor metastasis suppressor genes, CDH1, nm23-H1 and BRMS1, which may be responsible for the SA12-induced inhibition of breast cancer cell metastasis.

Furanoflavones pongapin and lanceolatin B blocks the cell cycle and induce senescence in CYP1A1-overexpressing breast cancer cells

Expression of cytochrome P450-1A1 (CYP1A1) is suppressed under physiologic conditions but is induced (a) by polycyclic aromatic hydrocarbons (PAHs) which can be metabolized by CYP1A1 to carcinogens, and (b) in majority of breast cancers. Hence, phytochemicals or dietary flavonoids, if identified as CYP1A1 inhibitors, may help in preventing PAH-mediated carcinogenesis and breast cancer. Herein, we have investigated the cancer chemopreventive potential of a flavonoid-rich Indian medicinal plant, Pongamia pinnata (L.) Pierre. Methanolic extract of its seeds inhibits CYP1A1 in CYP1A1-overexpressing normal human HEK293 cells, with IC₅₀ of 0.6 µg/mL. Its secondary metabolites, the furanoflavonoids pongapin/lanceolatin B, inhibit CYP1A1 with IC₅₀ of 20 nM. Although the furanochalcone pongamol inhibits CYP1A1 with IC₅₀ of only 4.4 µM, a semisynthetic pyrazole-derivative P5b, has ∼10-fold improved potency (IC₅₀, 0.49 μM). Pongapin/lanceolatin B and the methanolic extract of P. pinnata seeds protect CYP1A1-overexpressing HEK293 cells from B[a]P-mediated toxicity. Remarkably, they also block the cell cycle of CYP1A1-overexpressing MCF-7 breast cancer cells, at the G₀-G₁ phase, repress cyclin D1 levels and induce cellular-senescence. Molecular modeling studies demonstrate the interaction pattern of pongapin/lanceolatin B with CYP1A1. The results strongly indicate the potential of methanolic seed-extract and pongapin/lanceolatin B for further development as cancer chemopreventive agents.

Future in the Past: Azorella glabra Wedd. as a Source of New Natural Compounds with Antiproliferative and Cytotoxic Activity on Multiple Myeloma Cells

Multiple myeloma (MM) is the second most common hematologic malignancy and, although the development of novel agents has improved survival of patients, to date, it remains incurable. Thus, newer and more effective therapeutic strategies against this malignancy are necessary. Plant extracts play an important role in anti-tumor drug discovery. For this reason, in the investigation of novel natural anti-MM agents, we evaluated the phytochemical profiles, in vitro antioxidant activity, and effects on MM cells of Azorella glabra (AG) Wedd. Total polyphenols (TPC), flavonoids (TFC), and terpenoids (TTeC) contents were different among samples and the richest fractions in polyphenols demonstrated a higher antioxidant activity in in vitro assays. Some fractions showed a dose and time dependent anti-proliferative activity on MM cells. The chloroform fraction (CHCl₃) showed major effects in terms of reduction of cell viability, induction of apoptosis, and cell cycle arrest on MM cells. The apoptosis induction was also confirmed by the activation of caspase-3. Importantly, the CHCl₃ fraction exhibited a negligible effect on the viability of healthy cells. These results encourage further investigations on AG extracts to identify specific bioactive compounds and to define their potential applications in MM.

Downregulation of microRNA‑21 expression inhibits proliferation, and induces G1 arrest and apoptosis via the PTEN/AKT pathway in SKM‑1 cells

Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis and may progress to acute myeloid leukemia (AML). MicroRNAs (miRNA/miRs) as oncogenes or tumor suppressors regulate a number of biological processes including cell proliferation, cell cycle and apoptosis in different types of cancer cells. Recently, it has been reported that miR-21 as an oncogene is overexpressed and directly targets SMAD-7 in MDS. However, little is known about the mechanism of miR-21 in the progression of MDS. In the present study, the role of miR-21 in the proliferation and apoptosis of SKM-1 cells, an acute myeloid leukemia cell line established in the AML/MDS leukemic phase was investigated. The present results demonstrated that downregulation of miR-21 inhibited proliferation, induced apoptosis and caused G1 phase cell cycle arrest of SKM-1 cells. In addition, the expression levels of apoptosis regulator Bcl-2 (bcl2), cyclinD1 and phosphorylated-protein kinase B (AKT) were significantly decreased in SKM-1 cells transfected with the miR-21 inhibitor, whilst the expression levels of phosphatase and tensin homolog (PTEN), bcl-associated protein X (bax) and cleaved caspase 3 were significantly elevated. Furthermore, knockdown of Akt by small interfering (si)RNA significantly increased the expression of bax, cleaved caspase 3 and reduced the expression of bcl2 and cyclinD1 in SKM-1 cells. Taken together, these data indicate that miR-21 targets the PTEN/AKT pathway in the pathogenesis of MDS and could be a potential target for MDS therapy.