PPAR-gamma in overcoming kinase resistance in chronic myeloid leukemia

Peroxisome proliferator-activated receptor gamma (PPARγ) plays key roles in regulating cellular differentiation, proliferation and apoptosis pathways. As such, they are considered promising targets for anticancer drug development, especially for breast cancer, multiple myeloma and hematologic malignancies. Chronic myeloid leukemia (CML) is a myeloproliferative disorder arising from an oncogenic Bcr-Abl tyrosine kinase. Inhibitors of this oncogene by small molecules such as imatinib are effective only in 75% of the patient's population. One of the potential strategies to overcome this resistance is to devise combination therapy protocols with other therapeutic agents including PPAR ligands. Since PPAR ligands are potentially interesting in different hematologic malignancies, this article will review the potential of PPAR ligands for use in CML treatment.

Molecular profiling of prostate cancer derived exosomes may reveal a predictive signature for response to docetaxel

Docetaxel is a cornerstone treatment for metastatic, castration resistant prostate cancer (CRPC) which remains a leading cause of cancer-related deaths, worldwide. The clinical usage of docetaxel has resulted in modest gains in survival, primarily due to the development of resistance. There are currently no clinical biomarkers available that predict whether a CRPC patient will respond or acquire resistance to this therapy. Comparative proteomics analysis of exosomes secreted from DU145 prostate cancer cells that are sensitive (DU145 Tax-Sen) or have acquired resistance (DU145 Tax-Res) to docetaxel, demonstrated significant differences in the amount of exosomes secreted and in their molecular composition. A panel of proteins was identified by proteomics to be differentially enriched in DU145 Tax-Res compared to DU145 Tax-Sen exosomes and was validated by western blotting. Importantly, we identified MDR-1, MDR-3, Endophilin-A2 and PABP4 that were enriched only in DU145 Tax-Res exosomes. We validated the presence of these proteins in the serum of a small cohort of patients. DU145 cells that have uptaken DU145 Tax-Res exosomes show properties of increased matrix degradation. In summary, exosomes derived from DU145 Tax-Res cells may be a valuable source of biomarkers for response to therapy.

The Effect of Prednisolone on miR 15a and miR16-1 Expression Levels and Apoptosis in Acute Lymphoblastic Leukemia Cell Line: CCRF-CEM

BACKGROUND

Glucocorticoids are probably the most important drugs in the treatment of childhood acute lymphoblastic leukemia (ALL). Prednisolone exerts its effect by induce apoptosis in lymphoid lineage cells. Micro RNAs are 18-24 nucleotides RNA implicated in the control of essential biological functions, including apoptosis. In the following study, the effect of prednisolone on the expression of miR 15a & miR16-1 and apoptosis in the CCRF-CEM cell line is investigated.

METHODS

The cell line of CCRF-CEM was cultured in standard conditions. The changes in the miR 15a and miR 16-1 expression levels were determined by Real Time-PCR technique. Also, the apoptosis is evaluated by flow cytometry using Annexin V and PI staining.

RESULTS

This study revealed that, the prednisolone induced apoptosis in a time dependent manner. Prednisolone in concentration of 700 µM was significantly increased the expression of miR 16-1 and miR 15a after 24 h and 48 h treatment (p<0.05).

CONCLUSION

prednisolone-induced apoptosis might be mediated by up-regulation of these 2 miRNAs in CCRF-CEM cells.

Abstract B28: PTENpg1 antisense RNA mediates PTEN suppression in vemurafenib resistance and predicts clinical outcome in melanoma patients

Approximately 50% of cutaneous melanomas carry activating mutations in the serine/threonine protein kinase BRAF. Vemurafenib is a highly potent inhibitor of BRAFV600E and prolongs survival in ~80% of melanoma patients carrying the mutation. Unfortunately, almost all patients develop resistance within 6-8 months of starting treatment. The molecular mechanism explaining this scenario is largely unclear, but loss of PTEN expression, has been suggested.

In this study we reveal a role for the PTEN pseudogene encoded antisense RNA (PTENpg1 asRNA) in epigenetic suppression of PTEN in melanoma cell lines resistant to vemurafenib. Resistant cell lines showed increased PTENpg1 asRNA expression while PTEN expression was suppressed. ChIP analysis showed enrichment of the histone modification enzyme EZH2 and subsequent enrichment of H3K27me3 at the PTEN promoter in the resistant cell line. Total cellular levels of EZH2, DNMT3a and H3k27me3 were, however, unaffected thus indicating specific recruitment of these factors to the PTEN promoter in the resistant cells by a mechanism that is dictated by the increased expression of PTENpg1 asRNA. In addition, we show that PTEN is reactivated by the depletion of EZH2 and DNMT3a and that this reactivation of PTEN re-sensitizes the cells to vemurafenib treatment.

Finally, we show that PTENpg1 asRNA could be a promising prognostic marker of clinical outcome of melanoma patients. PTENpg1 asRNA expression levels were measured in samples from patients that had not received any oncological treatment and were classified with stage III melanomas. We found that high PTENpg1 asRNA expression correlates with short-term survival in melanoma patients.

In conclusions, the PTENpg1 asRNA appears to be an important player in vemurafenib resistance and could be an attractive therapeutic target. In addition, PTENpg1 asRNA is potentially a promising prognostic marker for clinical outcome for melanoma patients.

Citation Format: Linda Vidarsdottir, Alireza Azimi, Jason Serviss, Christian Ingvar, Göran Jönsson, Håkan Olsson, Marianne Frostvik Stolt, Johan Hansson, Suzanne Egyházi Brage, Dan Grandér, Per Johnsson. PTENpg1 antisense RNA mediates PTEN suppression in vemurafenib resistance and predicts clinical outcome in melanoma patients. [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer: Mechanisms to Medicines ; 2015 Dec 4-7; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2016;76(6 Suppl):Abstract nr B28.

Proteomics analysis of melanoma metastases: association between S100A13 expression and chemotherapy resistance

BACKGROUND

Disseminated cutaneous malignant melanoma (CMM) is commonly unresponsive to standard chemotherapies, and there are as yet no predictive markers of therapy response.

METHODS

In the present study we collected fresh-frozen pretreatment lymph-node metastasis samples (n=14) from melanoma patients with differential response to dacarbazine (DTIC) or temozolomide (TMZ) chemotherapy, to identify proteins with an impact on treatment response. We performed quantitative protein profiling using tandem mass spectrometry and compared the proteome differences between responders (R) and non-responders (NR), matched for age, gender and histopathological type of CMM.

RESULTS

Biological pathway analyses showed several signalling pathways differing between R vs NR, including Rho signalling. Gene expression profiling data was available for a subset of the samples, and the results were compared with the proteomics data. Four proteins with differential expression between R and NR were selected for technical validation by immunoblotting (ISYNA1, F13A1, CSTB and S100A13), and CSTB and S100A13 were further validated on a larger sample set by immunohistochemistry (n=48). The calcium binding protein S100A13 was found to be significantly overexpressed in NR compared with R in all analyses performed.

CONCLUSIONS

Our results suggest that S100A13 is involved in CMM resistance to DTIC/TMZ.

Differentiation of human endometrial stem cells into urothelial cells on a three-dimensional nanofibrous silk-collagen scaffold: an autologous cell resource for reconstruction of the urinary bladder wall

Reconstruction of the bladder wall via in vitro differentiated stem cells on an appropriate scaffold could be used in such conditions as cancer and neurogenic urinary bladder. This study aimed to examine the potential of human endometrial stem cells (EnSCs) to form urinary bladder epithelial cells (urothelium) on nanofibrous silk-collagen scaffolds, for construction of the urinary bladder wall. After passage 4, EnSCs were induced by keratinocyte growth factor (KGF) and epidermal growth factor (EGF) and seeded on electrospun collagen-V, silk and silk-collagen nanofibres. Later we tested urothelium-specific genes and proteins (uroplakin-Ia, uroplakin-Ib, uroplakin-II, uroplakin-III and cytokeratin 20) by immunocytochemistry, RT-PCR and western blot analyses. Scanning electron microscopy (SEM) and histology were used to detect cell-matrix interactions. DMEM/F12 supplemented by KGF and EGF induced EnSCs to express urothelial cell-specific genes and proteins. Either collagen, silk or silk-collagen scaffolds promoted cell proliferation. The nanofibrous silk-collagen scaffolds provided a three-dimensional (3D) structure to maximize cell-matrix penetration and increase differentiation of the EnSCs. Human EnSCs seeded on 3D nanofibrous silk-collagen scaffolds and differentiated to urothelial cells provide a suitable source for potential use in bladder wall reconstruction in women.

Sex-dependent hepatic transcripts and metabolites in the development of glucose intolerance and insulin resistance in Zucker diabetic fatty rats

Male Zucker diabetic fatty (mZDF) rats spontaneously develop type 2 diabetes, whereas females only become diabetic when fed a diabetogenic high-fat diet (high-fat-fed female ZDF rat, HF-fZDF). The aim of this study was to investigate if differences in liver functions could provide clues to this sex difference. Non-diabetic obese fZDF rats were compared with either mZDF or HF-fZDF regarding hepatic molecular profiles, to single out those components that might be protective in the females. High-fat feeding in fZDF led to enhanced weight gain, increased blood glucose and insulin levels, reduced insulin sensitivity and a trend towards reduced glucose tolerance, indicative of a prediabetic state. mZDF rats were diabetic, with low levels of insulin, high levels of glucose, reduced insulin sensitivity and impaired glucose tolerance. Transcript profiling and capillary electrophoresis time-of-flight mass spectrometry were used to indentify hepatic transcripts and metabolites that might be related to this. Many diet-induced alterations in transcript and metabolite levels in female rats were towards a 'male-like' phenotype, including reduced lipogenesis, increased fatty acid (FA) oxidation and increased oxidative stress responses. Alterations detected at the level of hepatic metabolites, indicated lower capacity for glutathione (GSH) production in male rats, and higher GSH turnover in females. Taken together, this could be interpreted as if anabolic pathways involving lipogenesis and lipid output might limit the degree of FA oxidation and oxidative stress in female rats. Together with a greater capacity to produce GSH, these hepatic sex differences might contribute to the sex-different development of diabetes in ZDF rats.

Abstract 3495: Targeted therapies in melanoma – in vitro effects of single and combined drug treatment

Malignant melanoma is one of the most rapidly increasing malignancies in Caucasian populations. So far, curative treatment is achieved only by surgical resection at an early stage, while the prognosis in cases with disseminated melanoma is poor, and we lack predictive tools to identify the few patients who respond to existing chemotherapy. Promising clinical trials of targeted therapies are ongoing, however, it is already clear that drug resistance will be a clinical reality also for these new therapies. Thus, novel predictive markers are urgently needed to identify responders to different types of therapy in melanoma.

The aim of the study is to unravel molecular mechanisms and pathways underlying resistance to new therapies in melanoma.

We are studying the effects of a set of MAPK and PI3K pathways inhibitors in melanoma cell lines that are wildtype or have different mutations/deletions in genes affecting these pathways (BRAF, NRAS, PTEN etc.). Cells are exposed to single drugs as well as combinations of inhibitors and/or chemotherapeutic agents.

Our results have shown that there is a wide range of sensitivity to the BRAF inhibitor PLX4720 among BRAF mutated cell lines, with IC50 values varying from 0.3 µM to 30 µM. We are investigating the underlying mechanisms causing this variation in sensitivity to the drug. Using gene expression profiling of a clinical material, we have identified several candidate genes that may predict response to DNA alkylating agents dacarbazine and temozolomide. The expression of some of these genes can be affected by PLX4720, and their potential relevance for response to different treatments is currently tested in vitro.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3495. doi:10.1158/1538-7445.AM2011-3495

Simultaneous pattern visual evoked potential and pattern electroretinogram in strabismic and anisometropic amblyopia

BACKGROUND

Amblyopia is a relatively common condition in which visual acuity through an eye is subnormal despite no overt pathology. Pattern visual evoked potential (PVEP) can detect any defect from optic nerve to occipital cortex and pattern electroretinogram (PERG) can detect retinal defects specially the ganglion layers. This study was performed to evaluate the cortical and retinal activity in strabismic and anisometropic amblyopia.

METHODS

PVEP and PERG were recorded simultaneously in 40 amblyopes (20 strabismics and 20 anisometropics) and 20 normal control subjects. Normal subjects were age and sex matched with patients.

RESULTS

The P(100) latency in PVEP was increased in both groups of patients but the P(100) amplitude was reduced only in anisometropic group. In PERG, the amplitude of P(50) was reduced in all patients with no significant change in latency.

CONCLUSION

Beside reduced PVEP responses in strabismic and anisometropic amblyopia, the activity of retina reduced too. It is likely that retinal impulses can affect the development of visual system.