New In Vitro Cellular Model for Molecular Studies of Retinitis Pigmentosa.

Retinitis pigmentosa (RP) is an inherited form of retinal degeneration characterized by primary rod photoreceptor cell death followed by cone loss. Mutations in several genes linked to the disease cause increased levels of cyclic guanosine monophosphate (cGMP) and calcium ion influxes. The purpose of this project was to develop a new in vitro photoreceptor degeneration model for molecular studies of RP. 661W cells were genetically modified to stably express the neural retina leucine zipper (NRL) transcription factor. One clone (661W-A11) was selected based on the expression of Nrl target genes. 661W-A11 showed a significant increase in expression of rod-specific genes but not of cone-specific genes, compared with 661W cells. Zaprinast was used to inhibit phosphodiesterase 6 (PDE6) activity to mimic photoreceptor degeneration in vitro. The activation of cell death pathways resulting from PDE6 inhibition was confirmed by detection of decreased viability and increased intracellular cGMP and calcium, as well as activation of protein kinase G (PKG) and calpains. In this new in vitro system, we validated the effects of previously published neuroprotective drugs. The 661W-A11 cells may serve as a new model for molecular studies of RP and for high-throughput drug screening.

Novel 2'-alkoxymethyl substituted klavuzon derivatives as inhibitors of Topo I and CRM1.

In this work, 2'-alkoxymethyl substituted klavuzon derivatives were prepared starting from 2-methyl-1-naphthoic acid in eight steps. Anticancer potencies of the synthesized compounds were evaluated by performing MTT cell viability test over cancerous and healthy pancreatic cell lines, along with CRM1 inhibitory properties in HeLa cells by immunostaining and Topo I inhibition properties by supercoiled DNA relaxation assay. Their cytotoxic activities were also presented in hepatocellular carcinoma cells (HuH-7) derived 3D spheroids. Among the tested klavuzon derivatives, isobutoxymethyl substituted klavuzon showed the highest selectivity of cytotoxic activity against pancreatic cancer cell line. They showed potent Topo I inhibition while their CRM1 inhibitory properties somehow diminished compared to 4'-alkylsubstituted klavuzons. The most cytotoxic 2'-methoxymethyl derivative inhibited the growth of the spheroids derived from HuH-7 cell lines and PI staining exhibited time and concentration dependent cell death in 3D spheroids.

CRM1 inhibitory and antiproliferative activities of novel 4'-alkyl substituted klavuzon derivatives.

Klavuzons are 6-(naphthalen-1-yl) substituted 5,6-dihydro-2H-pyran-2-one derivatives showing promising antiproliferative activities in variety of cancer cell lines. In this work, racemic syntheses of nine novel 4'-alkyl substituted klavuzon derivatives were completed in eight steps and anticancer properties of these compounds were evaluated. It is found that size of the substituent has dramatic effect over the potency and selectivity of the cytotoxic activity in cancerous and healthy pancreatic cell lines. The size of the substituent can also effect the CRM1 inhibitory properties of klavuzon derivatives. Strong cytotoxic activity and CRM1 inhibition can be observed only when a small substituent present at 4'-position of naphthalen-1-yl group. However, these substituents makes the molecule more cytotoxic in healthy pancreatic cells rather than cancerous pancreatic cells. Among the tested compounds 1,2,3,4-tetrahydrophenanthren-9-yl substituted lactone was the most cytotoxic compound and its antiproliferative activity was also tested in 3D spheroids generated from HuH-7 cell lines.

Targeting molecular pathways for the treatment of inherited retinal degeneration.

Inherited retinal degeneration is a major cause of incurable blindness characterized by loss of retinal photoreceptor cells. Inherited retinal degeneration is characterized by high genetic and phenotypic heterogeneity with several genes mutated in patients affected by these genetic diseases. The high genetic heterogeneity of these diseases hampers the development of effective therapeutic interventions for the cure of a large cohort of patients. Common cell demise mechanisms can be envisioned as targets to treat patients regardless the specific mutation. One of these targets is the increase of intracellular calcium ions, that has been detected in several murine models of inherited retinal degeneration. Recently, neurotrophic factors that favor the efflux of calcium ions to concentrations below toxic levels have been identified as promising molecules that should be evaluated as new treatments for retinal degeneration. Here, we discuss therapeutic options for inherited retinal degeneration and we will focus on neuroprotective approaches, such as the neuroprotective activity of the Pigment epithelium-derived factor. The characterization of specific targets for neuroprotection opens new perspectives together with many questions that require deep analyses to take advantage of this knowledge and develop new therapeutic approaches. We believe that minimizing cell demise by neuroprotection may represent a promising treatment strategy for retinal degeneration.