Oxidative Stress Resistance in Metastatic Prostate Cancer: Renewal by Self-Eating

PLoS One. 2015 Dec 15;10(12):e0145016. doi: 10.1371/journal.pone.0145016. eCollection 2015.

Abstract

Resistant cancer phenotype is a key obstacle in the successful therapy of prostate cancer. The primary aim of our study was to explore resistance mechanisms in the advanced type of prostate cancer cells (PC-3) and to clarify the role of autophagy in these processes. We performed time-lapse experiment (48 hours) with ROS generating plumbagin by using multimodal holographic microscope. Furthermore, we also performed the flow-cytometric analysis and the qRT-PCR gene expression analysis at 12 selected time points. TEM and confocal microscopy were used to verify the results. We found out that autophagy (namely mitophagy) is an important resistance mechanism. The major ROS producing mitochondria were coated by an autophagic membrane derived from endoplasmic reticulum and degraded. According to our results, increasing ROS resistance may be also accompanied by increased average cell size and polyploidization, which seems to be key resistance mechanism when connected with an escape from senescence. Many different types of cell-cell interactions were recorded including entosis, vesicular transfer, eating of dead or dying cells, and engulfment and cannibalism of living cells. Entosis was disclosed as a possible mechanism of polyploidization and enabled the long-term survival of cancer cells. Significantly reduced cell motility was found after the plumbagin treatment. We also found an extensive induction of pluripotency genes expression (NANOG, SOX2, and POU5F1) at the time-point of 20 hours. We suppose, that overexpression of pluripotency genes in the portion of prostate tumour cell population exposed to ROS leads to higher developmental plasticity and capability to faster respond to changes in the extracellular environment that could ultimately lead to an alteration of cell fate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagy / drug effects
  • Cell Communication / drug effects
  • Cell Line, Tumor
  • Cell Self Renewal* / drug effects
  • Cell Size / drug effects
  • Cell Survival / drug effects
  • Endoplasmic Reticulum / drug effects
  • Endoplasmic Reticulum / metabolism
  • Entosis / drug effects
  • Flow Cytometry
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Inhibitory Concentration 50
  • Male
  • Mitophagy / drug effects
  • Naphthoquinones / pharmacology
  • Neoplasm Metastasis
  • Oxidative Stress* / drug effects
  • Principal Component Analysis
  • Prostatic Neoplasms / genetics
  • Prostatic Neoplasms / pathology*
  • Reactive Oxygen Species / metabolism
  • Time-Lapse Imaging

Substances

  • Naphthoquinones
  • Reactive Oxygen Species
  • plumbagin

Grants and funding

This work was supported by funds from the Faculty of Medicine, Masaryk University to junior researcher (Michal Masarik) and by the project MUNI/A/1549/2014 and MUNI/A/1326/2014 with the support of the Specific University Research Grant, as provided by the Ministry of Education, Youth and Sports of the Czech Republic in the year 2015. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The commercial company (TESCAN) provided support in the form of salary for author Aneta Krizova, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific role of this author is articulated in the ‘author contributions’ section.