title: Synthesis and biologic properties of hydrophilic sapphyrins, a new class of tumor-selective inhibitors of gene expression.
abstract: BACKGROUND
  Sapphyrin analogues and related porphyrin-like species have attracted attention as anticancer agents due to their selective localization in various cancers, including hematologic malignancies, relative to surrounding tissues. Sapphyrins are electron affinic compounds that generate high yields of singlet oxygen formation. Although initially explored in the context of photodynamic therapy, sapphyrins have intrinsic anticancer activity that is independent of their photosensitizing properties. However, the mechanisms for their anticancer activity have not been fully elucidated.
  
  
  RESULTS
  We have prepared a series of hydrophilic sapphyrins and evaluated their effect on proliferation, uptake, and cell death in adherent human lung (A549) and prostate (PC3) cancer cell lines and in an A549 xenograft tumor model. PCI-2050, the sapphyrin derivative with the highest in vitro growth inhibitory activity, significantly lowered 5-bromo-2'-deoxyuridine incorporation in S-phase A549 cells by 60% within eight hours and increased levels of reactive oxygen species within four hours. The growth inhibition pattern of PCI-2050 in the National Cancer Institute 60 cell line screen correlated most closely using the COMPARE algorithm with known transcriptional or translational inhibitors. Gene expression analyses conducted on A549 plateau phase cultures treated with PCI-2050 uncovered wide-spread decreases in mRNA levels, which especially affected short-lived transcripts. Intriguingly, PCI-2050 increased the levels of transcripts involved in RNA processing and trafficking, transcriptional regulation, and chromatin remodeling. We propose that these changes reflect the activation of cellular processes aimed at countering the observed wide-spread reductions in transcript levels. In our A549 xenograft model, the two lead compounds, PCI-2050 and PCI-2022, showed similar tumor distributions despite differences in plasma and kidney level profiles. This provides a possible explanation for the better tolerance of PCI-2022 relative to PCI-2050.
  
  
  CONCLUSIONS
  Hydrophilic sapphyrins were found to display promise as novel agents that localize to tumors, generate oxidative stress, and inhibit gene expression.
authors.affiliation: Pharmacyclics, Inc., Sunnyvale, California, USA. zwang@pcyc.com
authors.forename: Zhong
authors.initials: Z
authors.lastname: Wang
authors.forename: Philip S
authors.initials: PS
authors.lastname: Lecane
authors.forename: Patricia
authors.initials: P
authors.lastname: Thiemann
authors.forename: Qing
authors.initials: Q
authors.lastname: Fan
authors.forename: Cecilia
authors.initials: C
authors.lastname: Cortez
authors.forename: Xuan
authors.initials: X
authors.lastname: Ma
authors.forename: Danielle
authors.initials: D
authors.lastname: Tonev
authors.forename: Dale
authors.initials: D
authors.lastname: Miles
authors.forename: Louie
authors.initials: L
authors.lastname: Naumovski
authors.forename: Richard A
authors.initials: RA
authors.lastname: Miller
authors.forename: Darren
authors.initials: D
authors.lastname: Magda
authors.forename: Dong-Gyu
authors.initials: DG
authors.lastname: Cho
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Sessler
authors.forename: Brian L
authors.initials: BL
authors.lastname: Pike
authors.forename: Samantha M
authors.initials: SM
authors.lastname: Yeligar
authors.forename: Mazen W
authors.initials: MW
authors.lastname: Karaman
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Hacia
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D015394:Molecular Structure; D020411:Oligonucleotide Array Sequence Analysis; D011166:Porphyrins / Q000493:pharmacokinetics* / Q000633:toxicity*; D017382:Reactive Oxygen Species / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D011166:Porphyrins; D017382:Reactive Oxygen Species; C440448:sapphyrin