Computational Identification of microRNA-17-3p in Breast Cancer Cells

c-Myc inhibits LAPTM5 expression in B-cell lymphomas

Myc is a pivotal protooncogenic transcription factor that contributes to the development of almost all Burkitt's lymphomas and about one-third of diffuse large B-cell lymphomas. How B-cells sustain their uncontrolled proliferation due to high Myc is not yet well defined. Here, we found that Myc trans-represses the expression of murine LAPTM5, a gene coding a lysosome-associated protein, by binding to two E-boxes in the LAPTM5 promoter. While the product of intact mRNA (CDS+3'UTR) of LAPTM5 failed to suppress the growth of B-lymphomas, either the protein coded by coding sequence (CDS) itself or the non-coding 3'-untranslated region (3'UTR) mRNA was able to inhibit the growth of B-lymphomas. Moreover, Myc trans-activated miR-17-3p, which promoted tumor growth. Strikingly, LAPTM5 3'UTR contains 11 miR-17-3p-binding sites through which the LAPTM5 protein synthesis was inhibited. The functional interplay between low LAPTM5 mRNA and high miR-17-3p due to high Myc in B-lymphomas leads to further dampening of tumor-suppressive LAPTM5 protein, which promotes tumor progression. Our results indicate that Myc inhibits LAPTM5 expression in B-lymphoma cells by transcriptional and post-transcriptional modifications.

Long Non-Coding RNA NLIPMT as a Tumor Suppressor and Inhibitor of Cell Proliferation and Metastasis in Papillary Thyroid Carcinoma

Introduction

Gene expression association studies of tumor samples have uncovered several long non-coding RNAs (lncRNAs) closely related to various types of cancer. Several lncRNAs have been reported to play essential roles in the progression of papillary thyroid carcinoma (PTC). Novel lncRNA inhibiting proliferation and metastasis (lnc-NLIPMT) is a known regulator of mammary cell proliferation and motility, but its involvement in PTC is unclear.

Materials and Methods

We investigated the role of lnc-NLIPMT in PTC by quantitative real-time polymerase chain reaction (qRT-PCR) on various PTC tissue samples and cell lines. We assessed the effects of overexpression or knockdown of lnc-NLIPMT on the proliferation, migration, and invasion of PTC cells using CCK-8, cell clone formation, and transwell assays. Changes in the expression of N-cadherin and vimentin were detected by immunoblotting.

Results

Our results revealed a downregulation of the expression of lnc-NLIPMT in PTC and a negative correlation between lnc-NLIPMT expression and tumor size (P=0.006). Overexpression of lnc-NLIPMT in TPC-1 and B-CPAP cells significantly suppressed cell proliferation, migration, and invasion, while lnc-NLIPMT knockdown had the opposite effect. In addition, lnc-NLIPMT played an important role in the regulation of the expression of N-cadherin and vimentin.

Conclusion

lnc-NLIPMT inhibits cell proliferation and metastasis of PTC cells and is a potential diagnostic and prognostic biomarker in PTC.