David L. Boucher

CWR22 has been a valuable xenograft model for the study of prostate cancer progression from an androgen-dependent tumor to one that grows in castrated animals. Herein, we report the identification and characterization of a novel androgen receptor (AR) mutation occurring in a relapsed tumor (CWR22R-2152) and in the CWR22Rv1 cell line established from it. The mutation was not detected in the original, hormone-dependent CWR22 xenograft, indicating that this change occurred during the progression to androgen independence. It is characterized by an in-frame tandem duplication of exon 3 that encodes the second zinc finger of the AR DNA-binding domain. Accordingly, immunoblot analyses demonstrated the expression of an AR species having an approximately 5-kDa increase in size relative to the LNCaP AR. This was accompanied by a COOH-terminally truncated AR species migrating with a relative mass of 75-80 kDa, referred to as ARDeltaLBD because it lacks the ligand-binding domain. By recreating the exon 3 duplication mutation in a wild-type AR expression construct, the generation of ARDeltaLBD could be recapitulated. Whereas ARDeltaLBD exhibited constitutive nuclear localization and DNA binding, these functions in the full-length AR remained androgen dependent. The CWR22Rv1 AR repertoire displayed dose-dependent, androgen-responsive transcriptional transactivation in reporter assays, albeit to a lesser extent in comparison with LNCaP. This cell line also expressed low levels of prostate-specific antigen mRNA and did not express or secrete detectable levels of prostate-specific antigen protein in androgen-depleted medium or in response to physiological androgenic stimulation. In summary, the CWR22Rv1 cell line displays both androgen-responsive and androgen-insensitive features due, at least in part, to a novel insertional mutation of the AR.

Cerenkov radiation is a phenomenon where optical photons are emitted when a charged particle moves faster than the speed of light for the medium in which it travels. Recently, we and others have discovered that measurable visible light due to the Cerenkov effect is produced in vivo following the administration of β-emitting radionuclides to small animals. Furthermore, the amounts of injected activity required to produce a detectable signal are consistent with small-animal molecular imaging applications. This surprising observation has led to the development of a new hybrid molecular imaging modality known as Cerenkov luminescence imaging (CLI), which allows the spatial distribution of biomolecules labelled with β-emitting radionuclides to be imaged in vivo using sensitive charge-coupled device cameras. We review the physics of Cerenkov radiation as it relates to molecular imaging, present simulation results for light intensity and spatial distribution, and show an example of CLI in a mouse cancer model. CLI allows many common radiotracers to be imaged in widely available in vivo optical imaging systems, and, more importantly, provides a pathway for directly imaging β(-)-emitting radionuclides that are being developed for therapeutic applications in cancer and that are not readily imaged by existing methods.

The artificial photosynthesis of ammonia , that is, the fixation of N 2 and conversion to NH 3 , is a fascinating research goal about which there are repeated reports of success in the literature. This communication now shows amongst other results why the obvious methods, in particular the heterogeneous catalysis of the reaction of N 2 and H 2 O on the surface of oxidic compounds, are destined to failure.

Androgen receptor (AR) is a ligand-induced transcriptional factor, which plays an important role in the normal development of prostate as well as in the progression of prostate cancer. Numerous coactivators, which associate with AR and function to remodel chromatin and recruit RNA polymerase II to enhance the transcriptional potential of AR, have been identified. Among these coactivators, few are protein kinases. In this study, we describe the characterization of a novel protein kinase, male germ cell-associated kinase (MAK), which serves as a coactivator of AR. We present evidence, which indicates that (a) MAK physically associates with AR (MAK and AR are found to be coprecipitated from cell extracts, colocalized in nucleus, and corecruited to prostate-specific antigen promoter in LNCaP as well as in transfected cells); (b) MAK is able to enhance AR transactivation potential in an androgen- and kinase-dependent manner in several prostate cancer cells and synergize with ACTR/steroid receptor coactivator-3 coactivator; (c) small hairpin RNA (shRNA) knocks down MAK expression resulting in the reduction of AR transactivation ability; (d) MAK-shRNA or kinase-dead mutant, when introduced into LNCaP cells, reduces the growth of the cells; and (e) microarray analysis of LNCaP cells carrying kinase-dead MAK mutant showed a significant impediment of AR signaling, indicating that endogenous MAK plays a general role in AR function in prostate cancer cells and likely to be a general coactivator of AR in prostate tissues. The highly restricted expression of this kinase makes it a potentially useful target for intervention of androgen independence.