5-ALA Fluorescence in Native Pituitary Adenoma Cell Lines: Resection Control and Basis for Photodynamic Therapy (PDT)?

Abstract

Objective: Pituitary adenomas (PA), especially invasive ones, are often not completely resectable. Usage of 5-aminolevulinic acid (5-ALA) for fluorescence guided surgery could improve the rate of total resection and, additionally, open the doors for photodynamic therapy (PDT) in case of unresectable or partially resected PAs. The aim of this study was to investigate the uptake of 5-ALA and the effect of 5-ALA based PDT in cell lines. Methods: GH3 and AtT-20 cell lines were incubated with different concentrations of 5-ALA, protoporphyrin IX (PPIX) fluorescence was measured by flow cytometry and fluorescencespectrometry. WST-1 assays were performed to determine the surviving fraction of cells after PDT. PPIX fluorescence intensities and PDT effect of the pituitary adenoma cells were compared to U373MG, a well-known glioblastoma cell line. Results: Both cell lines showed a 5-ALA dependent intracellular PPIX fluorescence. Significant differences after 24hrs of incubation were observed in AtT-20 cells in comparison to GH3. Regardless of the incubation or metabolism time, there was a proliferation inhibiting effect after PDT, with no statistical significance. Conclusion: Since GH3 cells showed a heterogenous uptake of 5-ALA in the flow cytometry profile, but not constantly high concentrations they might have a 5-ALA efflux mechanism, which still needs to be determined. In the case of AtT-20, the cells might need a longer time for the uptake due to their size or slow metabolism. We showed that the different cell lines have different uptake and metabolism mechanisms, which needs to be further investigated. The general uptake of 5-ALA allows the possibility of resection control and PDT for pituitary adenomas. But, the role of PDT for unresectable pituitary adenomas deserves further investigations.

How to Increase Brightness of Near-Infrared Fluorescent Proteins in Mammalian Cells

“…After 24 h of incubation with 5-ALA, the cells exhibited up to 21-fold higher NIR autofluorescence. This indicated that HeLa cells actively metabolized 5-ALA and likely accumulated the produced fluorescent PPIX (Figure 1), as observed in cancer cell lines (Krieg et al, 2002; Nemes et al, 2016). After normalization of NIR FP fluorescence to the increased autofluorescence we found that the real effective brightness of all NIR FPs has not changed and remained the same as without 5-ALA (Figure 3b).…”

Characterization of Perturbing Actions by Verteporfin, a Benzoporphyrin Photosensitizer, on Membrane Ionic Currents

“…Notably, it has been also demonstrated that BK Ca channels are functionally expressed in either retinal pigment epithelial cells, vascular endothelial cells, or amniotic fluid-derived stem cells (Li et al, 2000; Schmidt-Erfurth and Hasan, 2000; Sheu et al, 2005; Hua et al, 2014; Hu et al, 2015; Liu et al, 2015, 2018, 2019a,b). Taking this into account, to what extent VP-induced changes in BK Ca -channel activity existing in these cells are intimately connected with its actions on sensory retina or pituitary adenoma during photodynamic therapy (Marks et al, 2000; Rahimipour et al, 2003; Rosenblatt et al, 2005; Hu et al, 2015; Nemes et al, 2016; Liu et al, 2018; Min et al, 2018; Iacono et al, 2019) remains to be imperatively investigated.…”

“…Upon cell exposure to VP particularly along with long-term light exposure, the reactive oxygen species would be excessively produced, and resultant byproducts of oxidative metabolism can then interact with membrane phospholipids and proteins that constitute ion transport pathways such as BK Ca channels. Lastly, It will be worthy of being investigated regarding to what extent VP-mediated modifications on membrane ion channels reported herein is closely linked to the inhibition of VAP-TEAD complex followed by changes in proliferation or differentiation of different types of neoplastic or stem cells, given that the fact that such photosensitizers as sensitized photochemical modification in an array of tumors, including pituitary tumors and gliomas, have been widely utilized (Marks et al, 2000; Brown et al, 2004; Solban et al, 2006; Triesscheijn et al, 2006; Cole et al, 2008; Brodowska et al, 2014; Valero et al, 2015; Morishita et al, 2016; Nemes et al, 2016; Chen and Hu, 2017; Baskaran et al, 2018; Liao et al, 2018; Mulder et al, 2018; Chen et al, 2019; Li et al, 2019; Pellosi et al, 2019; Qin et al, 2019; Zhang et al, 2019). Alternatively, the efficacy of VP in inhibiting YAP/TEAD interaction was currently noted to remain debated (Lui et al, 2019).…”

“…The photodynamic therapy with different photosensitizers such as hypericin or VP has been previously demonstrated to be effective in the treatment of different types of hyper- or neoplastic tissues, including the residual small tumor in pituitary gland (Faustino et al, 1997; Marks et al, 2000; Valenzeno and Tarr, 2001; DeRosa and Crutchley, 2002; Rahimipour et al, 2003; Brown et al, 2004; Renno et al, 2004; Solban et al, 2006; Triesscheijn et al, 2006; Zhou et al, 2006; Cole et al, 2008; Tekrony et al, 2011; Nemes et al, 2016; Deng et al, 2018). Previous work indeed reported the capability of photosensitizers (e.g., rose bengal) to modify membrane ionic current in pituitary tumor (GH 3 ) cells or heart cells (Tarr et al, 1994; Valenzeno and Tarr, 1998, 2001).…”

Nkx3-1 and Fech Genes Might be Switch Genes Involved in Pituitary Non-Functioning Adenoma Invasiveness

“…A signi cant down-regulation of Fech expression was found in several malignancies [25][26][27][28], resulting in PpIX accumulation in such tumor cells. Indeed, accumulated PpIX in tumor cells leads to photodynamic therapy as effective adjuvant therapy for treating various cancers through visualizing the extent and margins of tumors, including PA [29].…”