PMID- 11522628
OWN - NLM
STAT- MEDLINE
DCOM- 20010913
LR  - 20220331
IS  - 0008-5472 (Print)
IS  - 0008-5472 (Linking)
VI  - 61
IP  - 17
DP  - 2001 Sep 1
TI  - Therapeutic implications of enhanced G(0)/G(1) checkpoint control induced by 
      coculture of prostate cancer cells with osteoblasts.
PG  - 6372-6
AB  - Osteoblastic metastases are common in lethal prostate cancer. Effective therapy 
      for bone metastases is lacking. Thus, developing an appropriate in vitro 
      screening system is critical to prioritize which of the newly developed agents 
      should undergo additional expensive and time-consuming in vivo evaluation in bone 
      metastases animal models. In the past, such in vitro screening evaluated the 
      response of prostate cancer cells to chemotherapeutic agents in monoculture 
      without the presence of osteoblasts. In such monoculture, prostate cancer cells 
      have a high (i.e., >90%) proliferative growth fraction. In contrast, the growth 
      fraction (i.e., mean: 7.1 +/- 0.8%; median: 3.1%) in 117 metastatic sites of 
      prostate cancer obtained from 11 androgen ablation failing patients at "warm" 
      autopsy was found to be >10-fold lower. To better mimic the lower growth fraction 
      observed clinically, LNCaP human prostate cancer cells were cocultured with 
      membrane-separated hFOB human osteoblasts. Such coculturing significantly lowered 
      the growth fraction of the LNCaP cells (i.e., from >90 to <30%) without enhancing 
      their low rate (i.e., <5%) of apoptosis. This lowering of the growth fraction was 
      documented using flow cytometry, Ki-67 immunohistochemistry, and 
      5-bromo-2-deoxyuridine incorporation. Using RNase protection assays, it was 
      documented that coculture with osteoblasts causes enhanced p53, p27, and p21 
      expression leading to a decrease in the number of LNCaP cells entering the cell 
      cycle (i.e., enhanced number of LNCaP cells in G(0)-G(1) and a decrease in S and 
      G(2)-M and thus the growth fraction). This osteoblast-induced enhanced G(0)-G(1) 
      checkpoint control affected the chemosensitivity of LNCaP cells. This was 
      documented by coculturing LNCaP cells with hFOB cells to condition the medium for 
      3 days to lower the growth fraction to <30% before exposing the LNCaP cells for 
      48 h to various concentrations of Taxol, doxorubicin, or thapsigargin (TG). In 
      standard high (i.e., >90%) growth fraction cultures (i.e., cultures in the 
      absence of osteoblast-conditioned medium), there was a dose-dependent and 
      significant (P < 0.05) increase in apoptosis of LNCaP cells exposed to Taxol or 
      doxorubicin. In contrast, even the highest dose of Taxol (1 microM) did not 
      enhance apoptosis of lower growth fraction LNCaP cells cultured in 
      osteoblast-conditioned medium. Similarly, only the highest concentration of 
      doxorubicin (1 microM) enhanced apoptosis in lower growth fraction cells. In 
      contrast, 100 nM TG induced high levels of apoptosis in both lower and 
      high-growth fraction LNCaP cultures. These results demonstrate that the 
      osteoblast/LNCaP coculture system is a better in vitro screen than monoculture to 
      identify proliferation-independent agents for the treatment of prostate cancer 
      bone metastases, and TG is such an agent.
FAU - Pinski, J
AU  - Pinski J
AD  - Johns Hopkins Oncology Center, Johns Hopkins School of Medicine, Baltimore, 
      Maryland 21231, USA.
FAU - Parikh, A
AU  - Parikh A
FAU - Bova, G S
AU  - Bova GS
FAU - Isaacs, J T
AU  - Isaacs JT
LA  - eng
GR  - CA58236/CA/NCI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Cancer Res
JT  - Cancer research
JID - 2984705R
RN  - 0 (Antineoplastic Agents)
RN  - 0 (Culture Media, Conditioned)
RN  - 67526-95-8 (Thapsigargin)
RN  - 80168379AG (Doxorubicin)
RN  - P88XT4IS4D (Paclitaxel)
SB  - IM
MH  - Antineoplastic Agents/pharmacology
MH  - Apoptosis/drug effects/physiology
MH  - Cell Communication/*physiology
MH  - Cell Cycle/drug effects/physiology
MH  - Cell Division/drug effects/physiology
MH  - Coculture Techniques
MH  - Culture Media, Conditioned
MH  - Doxorubicin/pharmacology
MH  - G1 Phase/drug effects/*physiology
MH  - Humans
MH  - Male
MH  - Neoplasms, Hormone-Dependent/drug therapy/pathology
MH  - Osteoblasts/*cytology
MH  - Paclitaxel/pharmacology
MH  - Prostatic Neoplasms/*drug therapy/*pathology
MH  - Resting Phase, Cell Cycle/drug effects/*physiology
MH  - Thapsigargin/pharmacology
MH  - Tumor Cells, Cultured
EDAT- 2001/08/28 10:00
MHDA- 2001/09/14 10:01
CRDT- 2001/08/28 10:00
PHST- 2001/08/28 10:00 [pubmed]
PHST- 2001/09/14 10:01 [medline]
PHST- 2001/08/28 10:00 [entrez]
PST - ppublish
SO  - Cancer Res. 2001 Sep 1;61(17):6372-6.