Transcriptome Analysis Reveals Vimentin-Induced Disruption of Cell-Cell Associations Augments Breast Cancer Cell Migration

Preparation and Use of shRNA for Knocking Down Specific Genes

Short hairpin RNA (shRNA) is a technique used to silence gene expression stably in various cells. There are however several reported problems. First, the cloning of oligos can lead to ligation of multiple copies; second, premature termination of sequencing reaction during confirmation of hairpin template; third, microdeletions/substitutions in hairpin during cloning; and fourth, off target effects. In this chapter, we have described a retrovirus transduction-based protocol that can be used on cells in culture without encountering any of the reported issues. We have used this protocol to clone shRNA templates for at least 10 different genes and confirmed them by dideoxy sequencing. The knockdown of 75-90% for two mRNA expressing genes, CDH5 and keratin KRT80, and a long non-coding RNA, XIST, is presented here.

Site-Directed Mutagenesis to Mutate Multiple Residues in a Single Reaction

Site-directed mutagenesis (SDM) is a technique that allows mutation of specific nucleotide(s) in a codon to study its functional implications in a protein. Commercial kits are available, which require high-performance liquid chromatography purified oligos for this purpose. These kits are expensive, and they are not very efficient, so one has to sequence several clones to get a desired one. We present here a simple method that requires only crude oligos, commercially available high-fidelity enzymes, and the success rate is close to 100%. In addition, up to 6 different mutations can be introduced in one reaction without causing any fortuitous change in the vector backbone. Using this strategy, we have introduced 32 S/T➔A substitutions in the N-terminus head and 13 changes in the C-terminus tail domain of vimentin.

Decoding LINC00052 role in breast cancer by bioinformatic and experimental analyses

LncRNA is a group of transcripts with a length exceeding 200 nucleotides that contribute to tumour development. Our research group found that LINC00052 expression was repressed during the formation of breast cancer (BC) multicellular spheroids. Intriguingly, LINC00052 precise role in BC remains uncertain. We explored LINC00052 expression in BC patients` RNA samples (TCGA) in silico, as well as in an in-house patient cohort, and inferred its cellular and molecular mechanisms. In vitro studies evaluated LINC00052 relevance in BC cells viability, cell cycle and DNA damage. Results. Bioinformatic RNAseq analysis of BC patients showed that LINC00052 is overexpressed in samples from all BC molecular subtypes. A similar LINC00052 expression pattern was observed in an in-house patient cohort. In addition, higher LINC00052 levels are related to better BC patient´s overall survival. Remarkably, MCF-7 and ZR-75-1 cells treated with estradiol showed increased LINC00052 expression compared to control, while these changes were not observed in MDA-MB-231 cells. In parallel, bioinformatic analyses indicated that LINC00052 influences DNA damage and cell cycle. MCF-7 cells with low LINC00052 levels exhibited increased cellular protection against DNA damage and diminished growth capacity. Furthermore, in cisplatin-resistant MCF-7 cells, LINC00052 expression was downregulated. Conclusion. This work shows that LINC00052 expression is associated with better BC patient survival. Remarkably, LINC00052 expression can be regulated by Estradiol. Additionally, assays suggest that LINC00052 could modulate MCF-7 cells growth and DNA damage repair. Overall, this study highlights the need for further research to unravel LINC00052 molecular mechanisms and potential clinical applications in BC.

Vimentin promotes glioma progression and maintains glioma cell resistance to oxidative phosphorylation inhibition

PURPOSE

Glioma has been demonstrated as one of the most malignant intracranial tumors and currently there is no effective treatment. Based on our previous RNA-sequencing data for oxidative phosphorylation (OXPHOS)-inhibition resistant and OXPHOS-inhibition sensitive cancer cells, we found that vimentin (VIM) is highly expressed in the OXPHOS-inhibition resistant cancer cells, especially in glioma cancer cells. Further study of VIM in the literature indicates that it plays important roles in cancer progression, immunotherapy suppression, cancer stemness and drug resistance. However, its role in glioma remains elusive. This study aims to decipher the role of VIM in glioma, especially its role in OXPHOS-inhibition sensitivity, which may provide a promising therapeutic target for glioma treatment.

METHODS

The expression of VIM in glioma and the normal tissue has been obtained from The Cancer Genome Atlas (TCGA) database, and further validated in Human Protein Atlas (HPA) and Chinese Glioma Genome Atlas (CGGA). And the single-cell sequencing data was obtained from TISCH2. The immune infiltration was calculated via Tumor Immune Estimation Resource (TIMER), Estimation of Stromal and Immune Cells in Malignant Tumors using Expression Data (ESTIMATE) and ssGSEA, and the Immunophenoscore (IPS) was calculated via R package. The differentiated expressed genes were analyzed including GO/KEGG and Gene Set Enrichment Analysis (GSEA) between the VIM-high and -low groups. The methylation of VIM was checked at the EWAS and Methsurv. The correlation between VIM expression and cancer stemness was obtained from SangerBox. We also employed DepMap data and verified the role of VIM by knocking down it in VIM-high glioma cell and over-expressing it in VIM-low glioma cells to check the cell viability.

RESULTS

Vim is highly expressed in the glioma patients compared to normal samples and its high expression negatively correlates with patients' survival. The DNA methylation in VIM promoters in glioma patients is lower than that in the normal samples. High VIM expression positively correlates with the immune infiltration and tumor progression. Furthermore, Vim is expressed high in the OXPHOS-inhibition glioma cancer cells and low in the OXPHOS-inhibition sensitive ones and its expression maintains the OXPHOS-inhibition resistance.

CONCLUSIONS

In conclusion, we comprehensively deciphered the role of VIM in the progression of glioma and its clinical outcomes. Thus provide new insights into targeting VIM in glioma cancer immunotherapy in combination with the current treatment.