Hsp27 (HSPB1): a possible surrogate molecular marker for loss of heterozygosity (LOH) of chromosome 1p in oligodendrogliomas but not in astrocytomas

FoxD2-AS1 promotes glioma progression by regulating miR-185-5P/HMGA2 axis and PI3K/AKT signaling pathway

BACKGROUND/AIMS

The present study was aimed at exploring the role of long noncoding RNA (lncRNA) FOXD2-AS1 in the development and progression of glioma and the underlying mechanism of FOXD2-AS1/miR-185-5p/HMGA2 network in glioma via regulation of PI3K/Akt signaling pathway.

METHODS

Microarray analysis was used for preliminary screening for candidate lncRNAs and mRNAs in glioma tissues. qRT-PCR and Western blot were used to determine the expression of FOXD2-AS1. The potential effects of FOXD2-AS1 on the viability, mobility and apoptosis of glioma cells were evaluated using MTT assay, Transwell assays and flow cytometry. The xenograft tumor model was performed to examine the influence of the lncRNA FOXD2-AS1/miR-185-5p/HMGA2 network on the biological functions of glioma cells. Luciferase assay and immunoprecipitation assay were examined to dissect molecular mechanisms.

RESULTS

LncRNA FOXD2-AS1 was overexpressed in human glioma, and upregulated FOXD2-AS11 expression indicated higher WHO grade (p < 0.05). MiR-185-5p was downregulated, whereas HMGA2 was upregulated in glioma tissues in comparison with para-carcinoma tissues. FOXD2-AS1 could regulate the expression of HMGA2 via miR-185-5p. Knockdown of FOXD2-AS1 significantly inhibited proliferation and metastatic potential of glioma cells, whereas endogenous expression FOXD2-AS1 inhibited the glioma cell activity through targeting HMGA2.

CONCLUSIONS

lncRNA FOXD2-AS1 acted as a sponge of miR-185-5p and influenced the PI3K/Akt signaling pathway through regulating HMGA2. LncRNA FOXD2-AS1 modulated HMGA2 and PI3K/Akt downstream signaling through sponging miR-185-5p, thereby promoting tumorigenesis and progression of glioma.

Targeting Heat Shock Proteins in Cancer: A Promising Therapeutic Approach

Heat shock proteins (HSPs) are a large family of chaperones that are involved in protein folding and maturation of a variety of "client" proteins protecting them from degradation, oxidative stress, hypoxia, and thermal stress. Hence, they are significant regulators of cellular proliferation, differentiation and strongly implicated in the molecular orchestration of cancer development and progression as many of their clients are well established oncoproteins in multiple tumor types. Interestingly, tumor cells are more HSP chaperonage-dependent than normal cells for proliferation and survival because the oncoproteins in cancer cells are often misfolded and require augmented chaperonage activity for correction. This led to the development of several inhibitors of HSP90 and other HSPs that have shown promise both preclinically and clinically in the treatment of cancer. In this article, we comprehensively review the roles of some of the important HSPs in cancer, and how targeting them could be efficacious, especially when traditional cancer therapies fail.

Heat Shock Proteins and Cancer

Heat shock proteins (HSPs) constitute a large family of proteins involved in protein folding and maturation whose expression is induced by heat shock or other stressors. The major groups are classified based on their molecular weights and include HSP27, HSP40, HSP60, HSP70, HSP90, and large HSPs. HSPs play a significant role in cellular proliferation, differentiation, and carcinogenesis. In this article we comprehensively review the roles of major HSPs in cancer biology and pharmacology. HSPs are thought to play significant roles in the molecular mechanisms leading to cancer development and metastasis. HSPs may also have potential clinical uses as biomarkers for cancer diagnosis, for assessing disease progression, or as therapeutic targets for cancer therapy.

Effects of temozolomide (TMZ) on the expression and interaction of heat shock proteins (HSPs) and DNA repair proteins in human malignant glioma cells

We previously reported the association of HSPA1A and HSPB1 with high-grade astrocytomas, suggesting that these proteins might be involved in disease outcome and response to treatment. With the aim to better understand the resistance/susceptibility processes associated to temozolomide (TMZ) treatment, the current study was performed in three human malignant glioma cell lines by focusing on several levels: (a) apoptotic index and senescence, (b) DNA damage, and (c) interaction of HSPB1 with players of the DNA damage response. Three human glioma cell lines, Gli36, U87, and DBTRG, were treated with TMZ evaluating cell viability and survival, apoptosis, senescence, and comets (comet assay). The expression of HSPA (HSPA1A and HSPA8), HSPB1, O6-methylguanine-DNA methyltransferase (MGMT), MLH1, and MSH2 was determined by immunocytochemistry, immunofluorescence, and Western blot. Immunoprecipitation was used to analyze protein interaction. The cell lines exhibited differences in viability, apoptosis, and senescence after TMZ administration. We then focused on Gli36 cells (relatively unstudied) which showed very low recovery capacity following TMZ treatment, and this was related to high DNA damage levels; however, the cells maintained their viability. In these cells, MGMT, MSH2, HSPA, and HSPB1 levels increased significantly after TMZ administration. In addition, MSH2 and HSPB1 proteins appeared co-localized by confocal microscopy. This co-localization increased after TMZ treatment, and in immunoprecipitation analysis, MSH2 and HSPB1 appeared interacting. In contrast, HSPB1 did not interact with MGMT. We show in glioma cells the biological effects of TMZ and how this drug affects the expression levels of heat shock proteins (HSPs), MGMT, MSH2, and MLH1. In Gli36 cells, the results suggest that interactions between HSPB1 and MSH2, including co-nuclear localization, may be important in determining cell sensitivity to TMZ.

HspB1, HspB5 and HspB4 in Human Cancers: Potent Oncogenic Role of Some of Their Client Proteins

Human small heat shock proteins are molecular chaperones that regulate fundamental cellular processes in normal unstressed cells as well as in many cancer cells where they are over-expressed. These proteins are characterized by cell physiology dependent changes in their oligomerization and phosphorylation status. These structural changes allow them to interact with many different client proteins that subsequently display modified activity and/or half-life. Nowdays, the protein interactomes of small Hsps are under intense investigations and will represent, when completed, key parameters to elaborate therapeutic strategies aimed at modulating the functions of these chaperones. Here, we have analyzed the potential pro-cancerous roles of several client proteins that have been described so far to interact with HspB1 (Hsp27) and its close members HspB5 (αB-crystallin) and HspB4 (αA-crystallin).