The use of light as a means of therapy for bladder cancer (BC) has a long history but has been hampered by a lack of tumor specificity and therefore, damage to the normal bladder mucosa. Here, we describe a targeted form of photo-therapy called photoimmunotherapy (PIT) which targets EGFR-expressing BC. Anti-EGFR antibody panitumumab (pan) was labeled with the photo-absorber (PA), IRDye 700Dx (IR700), to create a pan IR700 antibody-PA conjugate which is activated by near-infrared radiation (NIR). BC tissue microarray (TMA) and BC cell lines were analyzed for expression of EGFR. Mechanism of PIT induced cell death was studied using proliferation assays, transmission electron microscopy (TEM), and production of reactive oxygen species. Finally, the in vivo effect was studied in xenografts. EGFR staining of TMAs showed that while most BCs have expression of EGFR to a varying degree, squamous cell carcinomas (SCC) have the highest expression of EGFR. Pan IR700 activated by NIR light rapidly killed UMUC-5 cells, a bladder SCC line. Pan alone, pan IR700 without NIR, or NIR alone had no effect on cells. TEM demonstrated that cell death is due to necrosis. Singlet oxygen species contributed towards cell death. NIR-PIT with pan IR700 reduced growth compared to only pan IR700 treated UMUC-5 xenograft tumors. PIT is a new targeted treatment for bladder cancer. Pan IR700-induced PIT selectively kills EGFR-expressing BC cells in vitro and in vivo and therefore warrants further therapeutic studies in orthotopic xenografts of BC and ultimately in patients.

The ability of sterols other than cholesterol (CHOL) to support membrane functions in membranes that normally contain CHOL as the primary, if not sole, sterol may be due, in part, to how well such sterols can mimic CHOL's behavior and physical properties in membranes. We compared the mixing properties of CHOL, 7-dehydrocholesterol (7DHC), and desmosterol (DES) in egg phosphatidylcholine-sterol monolayer films containing 10, 20, and 30 mol percent sterol, measuring pressure-area isotherms on a Langmuir-Blodgett trough with the aqueous, buffered subphase maintained at 37 degrees C. Under the conditions employed, the pressure-area isotherms for all three sterols were similar, with 7DHC exhibiting slightly larger molecular areas on the water surface at all compositions. These results are discussed in the context of the ability of sterols such as 7DHC and DES to substitute structurally and functionally for CHOL in biological membranes.

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