mRNAs biomarker related to the control of proliferation and cell death in HepG2/C3A spheroid and monolayer cultures treated with piperlongumine

Background: Cell culture (spheroid and 2D monolayer cultures) is an essential tool in drug discovery. Piperlongumine (PLN), a naturally occurring alkaloid present in the long pepper (Piper longum), has been implicated in the regulation of GSTP1 activity. In vitro treatment of cancer cells with PLN increases ROS (reactive oxygen species) levels and induces cell death, but its molecular mode of action has not been entirely elucidated. Methods: In this study, we correlated the antiproliferative effects (2D and 3D cultures) of PLN (CAS 20069­09-4, Sigma-Aldrich) with morphological and molecular analyses in HepG2/C3A cell line. We performed assays for cytotoxicity (MTT), comet assays for genotoxicity, induction of apoptosis, analysis of the cell cycle phase, and analysis of the membrane integrity by flow cytometry. Relative expression of mRNA of genes related to proliferation, apoptosis, cell cycle control, metabolism of xenobiotics, and reticulum endoplasmic stress. Results: PLN reduced the cell proliferation by the cell cycle arrest in G2/M. Changes in the mRNA expression for CDKN1A (4.9x) and CCNA2 (0.5x) of cell cycle control genes were observed. Cell death occurred due to apoptosis, which may have been induced by increased expression of proapoptotic mRNAs (BAK1, 3.1x; BBC3, 2.4x), and by an increase in 9 and 3/7 active caspases. PLN induced cellular injury by ROS generation and DNA damage. DNA damage induced MDM2 signaling (3.0x) associated with the appearance of the monastral spindle in mitosis. Genes associated with ROS degradation also showed increased mRNA expression (GSR, 2.0x; SOD1, 2.1x). PLN induce endoplasmic reticulum stress with the increase in the mRNA expression of ERN1 (4.5x) and HSPA14 (2.2x). The xenobiotic metabolism showed increased mRNA expression for CYP1A2 (2.2x) and CYP3A4 (3.4x). In addition to 2D culture, PLN treatment also inhibited the growth of 3D culture (spheroids). Conclusion: Thus, the findings of our study show that several gene expression biomarkers (mRNAs) and monastral spindle formation indicated the many pathways of damage induced by PLN treatment that contributes to its antiproliferative effects

A spheroid-based 3-D culture model for pancreatic cancer drug testing, using the acid phosphatase assay

Current therapy for pancreatic cancer is multimodal, involving surgery and chemotherapy. However, development of pancreatic cancer therapies requires a thorough evaluation of drug efficacy in vitro before animal testing and subsequent clinical trials. Compared to two-dimensional culture of cell monolayer, three-dimensional (3-D) models more closely mimic native tissues, since the tumor microenvironment established in 3-D models often plays a significant role in cancer progression and cellular responses to the drugs. Accumulating evidence has highlighted the benefits of 3-D in vitro models of various cancers. In the present study, we have developed a spheroid-based, 3-D culture of pancreatic cancer cell lines MIAPaCa-2 and PANC-1 for pancreatic drug testing, using the acid phosphatase assay. Drug efficacy testing showed that spheroids had much higher drug resistance than monolayers. This model, which is characteristically reproducible and easy and offers rapid handling, is the preferred choice for filling the gap between monolayer cell cultures and in vivo models in the process of drug development and testing for pancreatic cancer.