Implications of pleiotrophin in human PC3 prostate cancer cell growth in vivo

Abstract

Pleiotrophin (PTN) is a heparin‐binding growth factor with diverse functions related to tumor growth, angiogenesis, and metastasis. Pleiotrophin seems to have a significant role in prostate cancer cell growth and to mediate the stimulatory actions of other factors that affect prostate cancer cell functions. However, all studies carried out up to date are in vitro, using different types of human prostate cancer cell lines. The aim of the present work was to study the role of endogenous PTN in human prostate cancer growth in vivo. For this purpose, human prostate cancer PC3 cells were stably transfected with a plasmid vector, bearing the antisense PTN sequence, in order to inhibit PTN expression (AS‐PC3). Migration, apoptosis, and adhesion on osteoblastic cells were measured in vitro. In vivo, PC3 cells were s.c. injected into male NOD/SCID mice, and tumor growth, survival rates, angiogenesis, apoptosis, and the number of metastasis were estimated. Pleiotrophin depletion resulted in a decreased migration capability of AS‐PC3 cells compared with the corresponding mock‐transfected or the non‐transfected PC3 cells, as well as increased apoptosis and decreased adhesiveness to osteoblastic cells in vitro. In prostate cancer NOD/SCID mouse xenografts, PTN depletion significantly suppressed tumor growth and angiogenesis and induced apoptosis of cancer cells. In addition, PTN depletion decreased the number of metastases, providing a survival benefit for the animals bearing AS‐PC3 xenografts. Our data suggest that PTN is implicated in human prostate cancer growth in vivo and could be considered a potential target for the development of new therapeutic approaches for prostate cancer.

Pleiotrophin-induced endothelial cell migration is regulated by xanthine oxidase-mediated generation of reactive oxygen species

“…In the present study we show that XO mediates the stimulatory effect of PTN on cell migration and could be hypothesized that XO might also mediate the anti-apoptotic effect of PTN. This notion is in line with our data that human prostate cancer cells that express low PTN levels have increased rates of apoptosis (Tsirmoula et al, 2012), decreased migration Tsirmoula et al, 2012) and decreased growth and metastases in vivo (Tsirmoula et al, 2012), and based on the present study, these same cells have lower levels of ROS compared with the corresponding cells expressing normal PTN levels. These data are also in line with data showing that XO levels are elevated in patients with prostate cancer (Samra et al, 2011), as well as several other types of cancer, such as breast, lung and bladder cancer, non-Hodgkin lymphoma and acute lymphoblastic lymphoma (Samra et al, 2011;Güleç et al, 2003).…”

“…Similarly, higher PTN expression correlates with higher endogenous ROS levels (this study) and increased migration Tsirmoula et al, 2012) in human prostate cancer cells. The role of XO in PTN-induced endothelial cell migration is supported by the data showing that allopurinol and febuxostat, similarly to ROS scavenging and down-regulation Results are expressed as mean ± s.e.m.…”

“…We have previously shown that down-regulation of endogenous PTN in human prostate cancer LNCaP or PC3 (Tsirmoula et al, 2012) cells results in decreased ability of the cells to migrate and form colonies in soft agar in vitro, increased apoptosis and decreased growth in immunocompromised rats in vivo. In the present study, we used the same cells stably expressing antisense PTN and investigated whether endogenous PTN levels correlated with intracellular carboxy-DCF fluorescence.…”

“…Human umbilical vein endothelial cells (HUVEC), human glioma M059K cells, Chinese hamster ovary (CHO) cells deficient in endogenous β 3 and human prostate cancer epithelial cell lines LNCaP and PC3 were cultured as previously described Koutsioumpa et al, 2013;Tsirmoula et al, 2012). Stable CHO clones expressing wild-type β 3 or mutant β 3 Y773F/Y785F were generated as previously described .…”

The role of pleiotrophin in bone repair

“…Ribozyme targeting of PTN in a human melanoma cell line decreases vessel formation in the primary tumour, as well as metastases [2]. Antisense PTN expression in human prostate LNCaP cells decreases prostate cancer cell-induced angiogenesis in vitro and in vivo [71,72]. On the other hand, antisense PTN expression in rat glioma C6 cells decreases glioma cell-induced angiogenesis in vitro and in vivo [73] and PTN seems to act as an angiostatic factor in an in vivo neuroblastoma model that is resistant to irinotecan [74].…”