BRCA1 regulates insulin-like growth factor 1 receptor levels in ovarian cancer

Sensitization of Carboplatinum- and Taxol-Resistant High-Grade Serous Ovarian Cancer Cells Carrying p53, BRCA1/2 Mutations by Emblica officinalis (Amla) via Multiple Targets

Background: Ovarian cancer (OC), the most lethal gynecologic malignancy, is highly resistant to current treatment strategies. High-grade serous epithelial ovarian cancer (HGSOC) cells with increased somatic mutations and genomic instability and the resulting heterogeneous mutant phenotypes are highly resistant to therapy. Plant-derived natural products, including Amla (Emblica officinalis) extract (AE), have demonstrated potent anti-neoplastic properties. Recently we demonstrated that AE inhibits cell growth and the expression of angiogenic factors in OVCAR3 and SKOV3 OC cells in vitro as well as in xenografts in vivo. The goal of this study was to determine the anti-proliferative, anti-angiogenic and anti-metastatic effects of AE on carboplatinum- and taxol-resistant HGSOC cells carrying p53, BRCA1/2 mutations.

Methods: Anti-proliferative and anti-metastatic effects of AE on recently characterized carboplatinum- and taxol-resistant HGSOC cells (TOV3041G, OV866(2), OV4453 and, OV4485) was determined using the MTT, migration, invasion and spheroid assays in vitro. To understand the mechanism of AE-induced changes in angiogenesis-related hypoxia-inducible factor 1α (HIF-1α) and insulin growth factor receptor 1 (IGF1R), and EMT-associated SNAIL1 and E-cadherin proteins were studied using immunostaining and Western blotting. In vivo effects of AE were determined using mouse xenograft tumor model of OC developed by subcutaneous injection of OV4485 cells that carry mutant p53 and BRCA1, most aggressive and resistant among HGSOC cell lines used in this study. Tumor growth was measured using morphometry. Immunostaining and Western blotting were used to determine changes in Ki67 (proliferation marker), CD31 (angiogenesis marker) as well as changes in HIF-1α, IGF1R, SNAIL1 and E-cadherin proteins.

Results: AE significantly attenuated migration and invasiveness properties of all tested HGSOC cell phenotypes (P≤0.001), significantly reduced the expression of HIF-1α, IGF1R, and SNAIL1 and increased the expression of E-cadherin in all tested HGSOC cell lines (P=<0.05). Oral administration of AE for 4 weeks caused a significant regression of mouse xenograft tumor (>60%) that derived from OV4855 cells and decreased the expression of endothelial cell antigen-CD31, HIF-1α, IGF1R and SNAIL1 and increased the expression of E-cadherin in tumor tissues.

Conclusions: AE sensitizes platinum- and taxol-resistant heterogenous HGSOC cells carrying mutations in p53, BRCA1/2 genes, and attenuates their malignant characteristics through targeting key signaling mechanisms of angiogenesis and metastasis. AE is a potential adjunct therapeutic agent for treating resistant, mutant, heterogenous OC.

Elucidating the novel BRCA1 function as a non-genomic metabolic restraint in ER-positive breast cancer cell lines

Within populations carrying the same genetic predisposition, the penetrance of BRCA1 mutations has increased over time. Although linked to changes in lifestyle factors associated with energy metabolism, these observations cannot be explained by the established role of BRCA1 in DNA repair alone. We manipulated BRCA1 expression using tetracycline in the UBR60-bcl2 cell line (which has an inducible, tetracycline-regulated BRCA1 expression) and siRNA in oestrogen receptor(ER)-positive MCF7 and T47D breast cancer cells. Cellular responses to BRCA1 silencing and IGF-I actions were investigated using western blotting, 3-H Thymidine incorporation assay, cell fractionation and co-immunoprecipitation. We demonstrated that the loss of BRCA1 resulted in downregulation of a phosphorylated and inactive form of acetyl CoA Carboxylase-α (ACCA), with a concomitant increase in fatty acid synthase (FASN) abundance. BRCA1 was predominantly cytoplasmic in ER-positive breast cancer cells, compatible with the observation that BRCA1 physically associates with phosphorylated ACCA, which is a cytoplasmic protein. We also found that IGF-I induced de-phosphorylation of ACCA by reducing the interaction between BRCA1 and phosphorylated ACCA. BRCA1 deficiency enhanced the non-genomic effects of IGF-I, as well as the proliferative responses of cells to IGF-I. We characterized a novel, non-genomic role for BRCA1 in restraining metabolic activity and IGF-I anabolic actions.

RNA-Seq Analysis of Microglia Reveals Time-Dependent Activation of Specific Genetic Programs following Spinal Cord Injury

Neurons have inherent competence to regrow following injury, although not spontaneously. Spinal cord injury (SCI) induces a pronounced neuroinflammation driven by resident microglia and infiltrating peripheral macrophages. Microglia are the first reactive glial population after SCI and participate in recruitment of monocyte-derived macrophages to the lesion site. Both positive and negative influence of microglia and macrophages on axonal regeneration had been reported after SCI, raising the issue whether their response depends on time post-lesion or different lesion severity. We analyzed molecular alterations in microglia at several time-points after different SCI severities using RNA-sequencing. We demonstrate that activation of microglia is time-dependent post-injury but is independent of lesion severity. Early transcriptomic response of microglia after SCI involves proliferation and neuroprotection, which is then switched to neuroinflammation at later stages. Moreover, SCI induces an autologous microglial expression of astrocytic markers with over 6% of microglia expressing glial fibrillary acidic protein and vimentin from as early as 72 h post-lesion and up to 6 weeks after injury. We also identified the potential involvement of DNA damage and in particular tumor suppressor gene breast cancer susceptibility gene 1 (Brca1) in microglia after SCI. Finally, we established that BRCA1 protein is specifically expressed in non-human primate spinal microglia and is upregulated after SCI. Our data provide the first transcriptomic analysis of microglia at multiple stages after different SCI severities. Injury-induced microglia expression of astrocytic markers at RNA and protein levels demonstrates novel insights into microglia plasticity. Finally, increased microglia expression of BRCA1 in rodents and non-human primate model of SCI, suggests the involvement of oncogenic proteins after CNS lesion.

Insulin-like growth factor-1 signaling in renal cell carcinoma

Renal cell carcinoma (RCC) incidence is highest in highly developed countries and it is the seventh most common neoplasm diagnosed. RCC management include nephrectomy and targeted therapies. Type 1 insulin-like growth factor (IGF-1) pathway plays an important role in cell proliferation and apoptosis resistance. IGF-1 and insulin share overlapping downstream signaling pathways in normal and cancer cells. IGF-1 receptor (IGF1R) stimulation may promote malignant transformation promoting cell proliferation, dedifferentiation and inhibiting apoptosis. Clear cell renal cell carcinoma (ccRCC) patients with IGF1R overexpression have 70 % increased risk of death compared to patients who had tumors without IGF1R expression. IGF1R signaling deregulation may results in p53, WT, BRCA1, VHL loss of function. RCC cells with high expression of IGF1R are more resistant to chemotherapy than cells with low expression. Silencing of IGF1R increase the chemosensitivity of ccRCC cells and the effect is greater in VHL mutated cells. Understanding the role of IGF-1 signaling pathway in RCC may result in development of new targeted therapeutic interventions. First preclinical attempts with anti-IGF-1R monoclonal antibodies or fragment antigen-binding (Fab) fragments alone or in combination with an mTOR inhibitor were shown to inhibit in vitro growth and reduced the number of colonies formed by of RCC cells.

Brca1 is expressed in human microglia and is dysregulated in human and animal model of ALS

Background

There is growing evidence that microglia are key players in the pathological process of amyotrophic lateral sclerosis (ALS). It is suggested that microglia have a dual role in motoneurone degeneration through the release of both neuroprotective and neurotoxic factors.

Results

To identify candidate genes that may be involved in ALS pathology we have analysed at early symptomatic age (P90), the molecular signature of microglia from the lumbar region of the spinal cord of hSOD1^G93A mice, the most widely used animal model of ALS. We first identified unique hSOD1^G93A microglia transcriptomic profile that, in addition to more classical processes such as chemotaxis and immune response, pointed toward the potential involvement of the tumour suppressor gene breast cancer susceptibility gene 1 (Brca1). Secondly, comparison with our previous data on hSOD1^G93A motoneurone gene profile substantiated the putative contribution of Brca1 in ALS. Finally, we established that Brca1 protein is specifically expressed in human spinal microglia and is up-regulated in ALS patients.

Conclusions

Overall, our data provide new insights into the pathogenic concept of a non-cell-autonomous disease and the involvement of microglia in ALS. Importantly, the identification of Brca1 as a novel microglial marker and as possible contributor in both human and animal model of ALS may represent a valid therapeutic target. Moreover, our data points toward novel research strategies such as investigating the role of oncogenic proteins in neurodegenerative diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13024-015-0023-x) contains supplementary material, which is available to authorized users.