Verification and characterization of an alternative low density lipoprotein receptor-related protein 1 splice variant

PLoS One. 2017 Jun 29;12(6):e0180354. doi: 10.1371/journal.pone.0180354. eCollection 2017.


Background: Low density lipoprotein (LDL) receptor-related protein 1 (LRP1) is a ubiquitously expressed multi-ligand endocytosis receptor implicated in a wide range of signalling, among others in tumour biology. Tumour-associated genomic mutations of the LRP1 gene are described, but nothing is known about cancer-associated expression of LRP1 splice variants Therefore, the focus of this study was on an annotated truncated LRP1 splice variant (BC072015.1; NCBI GenBank), referred to as smLRP1, which was initially identified in prostate and lung carcinoma.

Methods: Using PCR and quantitative PCR, the expression of LRP1 and smLRP1 in different human tissues and tumour cell lines was screened and compared on tumour biopsies of head and neck squamous cell carcinoma (HNSCC). Using a recently developed anti-smLRP1 antibody, the expression of the putative LRP1 protein isoform in tumour cell lines in Western blot and immunofluorescence staining was further investigated.

Results: The alternative transcript smLRP1 is ubiquitously expressed in 12 human cell lines of different origin and 22 tissues which is similar to LRP1. A shift in expression of smLRP1 relative to LRP1 towards smLRP1 was observed in most tumour cell lines compared to healthy tissue. The expression of LRP1 as well as smLRP1 is decreased in HNSCC cell lines in comparison to healthy mucosa. In vitro results were checked using primary HNSCC. Furthermore, the expression of the protein isoform smLRP1 (32 kDa) was confirmed in human tumour cell lines.

Conclusions: Similar to LRP1, the truncated splice variant smLRP1 is ubiquitously expressed in healthy human tissues, but altered in tumours pointing to a potential role of smLRP1 in cancer. Comparative results suggest a shift in expression in favour of smLRP1 in tumour cells that warrant further evaluation. The protein isoform is suggested to be secreted.

MeSH terms

  • Alternative Splicing*
  • Amino Acid Sequence
  • Carcinoma, Squamous Cell / pathology
  • Cell Line, Tumor
  • Head and Neck Neoplasms / pathology
  • Humans
  • Low Density Lipoprotein Receptor-Related Protein-1 / chemistry
  • Low Density Lipoprotein Receptor-Related Protein-1 / genetics*
  • Sequence Homology, Amino Acid


  • Low Density Lipoprotein Receptor-Related Protein-1

Grants and funding

This work was supported by the European Social Fund (URL; grant number 100098250. Funding was granted to GB. We also acknowledge support from the German Research Foundation (DFG) and University of Leipzig within the program of Open Access Publishing. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.