Selection of internalizing RNA aptamers into human breast cancer cells derived from primary sites.

Breast cancer is the most common cancer in women. Although chemotherapy is still broadly used in its treatment, adverse effects remain a challenge. In this scenario, aptamers emerge as a promising alternative for theranostic applications. Studies using breast cancer cell lines provide useful information in laboratory and preclinical investigations, most of which use cell lines established from metastatic sites. However, these cell lines correspond to cell populations of the late stage of tumor progression. On the other hand, studies using breast cancer cells established from primary sites make it possible to search for new theranostic approaches in the early stages of the disease. Therefore, this work aimed to select RNA aptamers internalized by MGSO-3 cells, a human breast cancer cell line, derived from a primary site previously established in our laboratory. Using the Cell-Internalization SELEX method, we have selected two candidate aptamers (ApBC1 and ApBC2). We evaluated their internalization efficiencies, specificities, cellular localization by Reverse Transcription-qPCR (RT-qPCR) and confocal microscopy assays. The results suggest that both aptamers were efficiently internalized by human breast cancer cells, MACL-1, MDA-MB-231, and especially by MGSO-3 cells. Furthermore, both aptamers could effectively distinguish human breast cancer cells derived from normal human mammary cell (MCF 10A) and prostate cancer cell (PC3) lines. Therefore, ApBC1 and ApBC2 could be promising candidate molecules for theranostic applications, even in the early stages of tumor progression.

New developments of RNAi in Paracoccidioides brasiliensis: prospects for high-throughput, genome-wide, functional genomics.

BACKGROUND: The Fungal Genome Initiative of the Broad Institute, in partnership with the Paracoccidioides research community, has recently sequenced the genome of representative isolates of this human-pathogen dimorphic fungus: Pb18 (S1), Pb03 (PS2) and Pb01. The accomplishment of future high-throughput, genome-wide, functional genomics will rely upon appropriate molecular tools and straightforward techniques to streamline the generation of stable loss-of-function phenotypes. In the past decades, RNAi has emerged as the most robust genetic technique to modulate or to suppress gene expression in diverse eukaryotes, including fungi. These molecular tools and techniques, adapted for RNAi, were up until now unavailable for P. brasiliensis. METHODOLOGY/PRINCIPAL FINDINGS: In this paper, we report Agrobacterium tumefaciens mediated transformation of yeast cells for high-throughput applications with which higher transformation frequencies of 150±24 yeast cell transformants per 1×106 viable yeast cells were obtained. Our approach is based on a bifunctional selective marker fusion protein consisted of the Streptoalloteichus hindustanus bleomycin-resistance gene (Shble) and the intrinsically fluorescent monomeric protein mCherry which was codon-optimized for heterologous expression in P. brasiliensis. We also report successful GP43 gene knock-down through the expression of intron-containing hairpin RNA (ihpRNA) from a Gateway-adapted cassette (cALf) which was purpose-built for gene silencing in a high-throughput manner. Gp43 transcript levels were reduced by 73.1±22.9% with this approach. CONCLUSIONS/SIGNIFICANCE: We have a firm conviction that the genetic transformation technique and the molecular tools herein described will have a relevant contribution in future Paracoccidioides spp. functional genomics research.

The type III inositol 1,4,5-trisphosphate receptor preferentially transmits apoptotic Ca2+ signals into mitochondria.

There are three isoforms of the inositol 1,4,5- trisphosphate receptor (InsP(3)R), each of which has a distinct effect on Ca(2+) signaling. However, it is not known whether each isoform similarly plays a distinct role in the activation of Ca(2+)-mediated events. To investigate this question, we examined the effects of each InsP(3)R isoform on transmission of Ca(2+) signals to mitochondria and induction of apoptosis. Each isoform was selectively silenced using isoform-specific small interfering RNA in Chinese hamster ovary cells, which express all three InsP(3)R isoforms. ATP-induced cytosolic Ca(2+) signaling patterns were altered, regardless of which isoform was silenced, but in a different fashion depending on the isoform. ATP also induced Ca(2+) signals in mitochondria, which were inhibited more effectively by silencing the type III InsP(3)R than by silencing either the type I or type II isoform. The type III isoform also co-localized most strongly with mitochondria. When apoptosis was induced by activation of either the extrinsic or intrinsic apoptotic pathway, induction was reduced most effectively by silencing the type III InsP(3)R. These findings provide evidence that the type III isoform of the InsP(3)R plays a special role in induction of apoptosis by preferentially transmitting Ca(2+) signals into mitochondria.

GM-CSF and TNF-alpha synergize to increase in vitro granuloma size of PBMC from humans induced by Schistosoma mansoni recombinant 28-kDa GST.

The 28-kDa Glutathione S-transferase of Schistosoma mansoni (Sm28 GST) was described as a protective antigen capable of reducing female fecundity and the number of eggs in mice hepatic tissues. The role of GM-CSF and TNF-alpha in the in vitro granuloma reaction of peripheral blood mononuclear cells (PBMC) from chronic intestinal schistosomiasis patients before and after chemotherapy treatment to S. mansoni recombinant Sm28 GST was evaluated. Treatment of PBMC with recombinant Sm28 GST caused a significant increase in granuloma formation when compared to SEA or SWAP. Contrary to SEA or SWAP, Sm28 GST was not capable of inducing significant cellular proliferation. Moreover, recombinant Sm28 GST promoted a significant elevation in GM-CSF and TNF-alpha levels. However, we did not detect any significant IL-10 production. When Sm28 GST was applied in the presence of anti-GM-CSF or anti-TNF-alpha antibodies in cultures, we observed a significant decrease in granuloma size. Indeed, our results demonstrated that Sm28 GST was capable of promoting high in vitro granuloma index, and this event was associated with the balance of GM-CSF and TNF-alpha. These evidences suggest a role for GM-CSF as a major mediator in increasing granuloma reaction in human schistosomiasis. This event may contribute to exacerbate the pathology resulting from egg deposition in host tissues.