The HPV16E7 Affibody as a Novel Potential Therapeutic Agent for Treating Cervical Cancer Is Likely Internalized through Dynamin and Caveolin-1 Dependent Endocytosis

Abstract

Affibodies targeting intracellular proteins have a great potential to function as ideal therapeutic agents. However, little is known about how the affibodies enter target cells to interact with intracellular target proteins. We have previously developed the HPV16E7 affibody (ZHPV16E7384) for HPV16 positive cervical cancer treatment. Here, we explored the underlying mechanisms of ZHPV16E7384 and found that ZHPV16E7384 significantly inhibited the proliferation of target cells and induced a G1/S phase cell cycle arrest. Furthermore, ZHPV16E7384 treatment resulted in the upregulation of retinoblastoma protein (Rb) and downregulation of phosphorylated Rb (pRb), E2F1, cyclin D1, and CDK4 in the target cells. Moreover, treatment with dynamin or the caveolin-1 inhibitor not only significantly suppressed the internalization of ZHPV16E7384 into target cells but also reversed the regulation of cell cycle factors by ZHPV16E7384. Overall, these results indicate that ZHPV16E7384 was likely internalized specifically into target cells through dynamin- and caveolin-1 mediated endocytosis. ZHPV16E7384 induced the cell cycle arrest in the G1/S phase at least partially by interrupting HPV16E7 binding to and degrading Rb, subsequently leading to the downregulation of E2F1, cyclin D1, CDK4, and pRb, which ultimately inhibited target cell proliferation. These findings provide a rationale of using ZHPV16E7384 to conduct a clinical trial for target therapy in cervical cancer.

Effects and mechanism of APPL1 on proliferation of gastric cancer cells

“…CyclinD1 is one of the key proteins in the regulation of cell proliferation, which regulates cell proliferation mainly by regulating the G1/S conversion rate of the cell cycle [15] . In cell mitosis, Cyclin D1 is able to phosphorylate Rb by binding to a cyclin-dependent kinase, which in turn regulates cells from G1 phase to S phase [16][17] . Both p16 and p27 can block the formation of a complex with Cyclin D1 by binding to cyclin-dependent kinase 4, thus arresting cell division and proliferation [18][19] .…”

The Inhibitory Effect of an HPV16E7-Specific Affibody Conjugated to Granzyme B (GrB) on Cervical Cancer Cells by Bifunctional Activity

“…Currently, genetically engineered antibodies, such as chimeric Abs, mini-molecular Abs, and bispecific Abs, have made antibody drugs more extensively applicable. A novel "artificial antibody" with high affinity and specificity for target proteins, named an affibody, has more significant advantages than antibodies for targeted therapy [9] , for example, better entry into cells [10] . Because affibodies can also recognize and bind antigen as antibodies but without the other functional regions in antibodies that may cause immunological side effects, affibodies do not have the application limitations of antibodies.…”