Download Activation of macrophages after platinum coordination

Activation of macrophages after platinum coordination complexes ,
S. K. Aggarwal, D. Telgenhoff and H. Muenchen
Department of Zoology, Michigan State University, East Lansing, Michigan, U.S.A. 48824-l 115
Cisplatin (ck-di amminedichloroplatinum II; CDDP) is a broad spectrum anti-cancer
agent which acts through the inhibition of DNA transcription and its replication. If the DNA has already
been replicated it still inhibits cytokinesis through the depolymerization of actin like microfilaments [ 11.
More recently it has been demonstrated to enhance the immune system through the activation of
marophages (peritoneal and Kupffer cells) both in vivo and in vitro [2]. Although cisplatin is effective
in the treatment of various cancers but suffers from severe toxic side effects. Newer compounds with
various ligand substitutions are being made and tested to increase the effkacy and lower the toxicity due
normal tissues. Of these second generation analogs of CDDP,
Poly-[(trans- 1,2diaminocyclohexane)platinum]-carboxylase (“poly-plat”) is one such compound that is water soluble
and is stable in solution. In equimolar concentrations poly-plat has l/5 platinum compared to CDDP
and has a prolonged in vivo half life. It has been shown to be much more effective in the activation of
various macrophages [2]. In in vivo renal cancer model resistant to other agents it has been shown to
be very effective[3].
Swiss Webster mice were treated, with CDDP and “poly-plat” (10 mgkg)(Andrulis
Pharmaceuticals, Beltsville, MD) for 2 and 12 days at the end of which animals were hilled and Liver
tissue was fixed in 4% buffered formaldehyde and processed for routine electron microscopy studies.
The peritoneal macrophages from both the normal and drug treated animals were isolated and cultured
for 24 h. Structural morphologies and supernatant analysis were made for lysosomal and cytolytic
factors including interleukin-lalpha, TNF-alpha and nitric oxide using electron microscopy and
immunocytochernistry [4].
CDDP and “poly-plat” treatments induce an activation of the peritoneal macrophages
and the
Kupffer cells through cell growth and development of cytoplasmic extensions, enhanced number of
Iysosomes and the activity of various cytolytic factors. In the normal liver Kupffer cells appear rounded
with large nucleus and few cytoplasmic extensions (Figs. l-2). After CDDP treatment, however, the
Kupffer cells show an increase in their cell size and enormous cytoplasmic extensions (Figs. 3-4).
These results show that the Kupffer cells in vivo have similar mechanisms of activation as in vitro. In
vitro experiments drug- treated peritoneal macrophages when exposed to the tumor cells show
cytoplasmic contacts and transfer of lysosomes resulting in tumor cell lysis. Using platinum-pyrimidine
complexes as stains for electron microscopy it has been proposed that CDDP and its analogs probably
enhance the antigenicity of the tumor cells (Fig. 5) by binding to the surface associated DNA [S]. Coculturing with normal cells the macrophages do not show any activity.
“Poly-plat” treatment of the macrophages induced a 500 fold increase in the number of
lysosomes where as CDDP treatment only shows a 50 fold increase. Transfer of such macrophagic
lysosomes into the tumor cells was observed within 2 h of co-incubation with tumor cells resulting in
their lysis within 24 h. Analysis of tissue culture medium from “poly-plat” treatments demonstrated a
50 fold increase in the interleukin-1 alpha which was twice that observed after CDDP. It seems that
“poly-plat” is able to enhance the immune system more effkiently with lesser atoms of platinum per
molecule than CDDP but its toxicities still need be explored.
1. Aggarwal, S. K., J Histochem Cytochem, 4 1 (1993) 1053.
2. Muenchen, H. J. et al ., Anti-Cancer Drugs, 8 (1997) 323.
3. Fiebig, H.H. et al., Proc. Am. Ass Cancer Res., 37 (1996) 297.
4. Muenchen, H. J. and Aggarwal, S. K., Anti-Cancer Drugs, 9 (1998) 93.
5. Aggarwal, S. K. et al., Proc. Natl. Acad. Sci. USA, 72 (1975) 928.
FIGS.
1-2.
Micrographs showing the normal macrophages
at the light or the electron microscope level.
FIGS.
3-4. “Poly-plat”-treated
FIG.
5.
with no cytoplasmic
macrophages showing extensive cytoplasmic
increased number of lysosomes (arrows).
extensions
extensions and
Micrograph showing the surface associated binding of platinum thymine blue in
Sarcoma 180 cell.