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Anomalous dystroglycan in carcinoma cell lines
C Losasso1, F Di Tommaso, A Sgambato
1Centro Chimica dei Recettori (CNR), Istituto di Chimica e Chimica Clinica, Università Cattolica del Sacro Cuore, Rome, Italy.
Abstract:
Dystroglycan is a receptor responsible for crucial interactions between extracellular matrix and cytoplasmic space. We provide the first evidence that dystroglycan is truncated. In HC11 normal murine and the 184B5 non-tumorigenic mammary human cell lines, the expected beta-dystroglycan 43 kDa band was found but human breast T47D, BT549, MCF7, colon HT29, HCT116, SW620, prostate DU145 and cervical HeLa cancer cells expressed an anomalous approximately 31 kDa beta-dystroglycan band. alpha-Dystroglycan was udetectable in most of the cell lines in which beta-dystroglycan was found as a approximately 31 kDa species. An anomalous approximately 31 kDa beta-dystroglycan band was also observed in N-methyl-N-nitrosurea-induced primary rat mammary tumours. Reverse transcriptase polymerase chain reaction experiments confirmed the absence of alternative splicing events and/or expression of eventual dystroglycan isoforms. Using protein extraction procedures at low- and high-ionic strength, we demonstrated that both the 43 kDa and approximately 31 kDa beta-dystroglycan bands harbour their transmembrane segment.
Insights
Dystroglycan, a key cell receptor, is found to be truncated in various cancer cells. This truncation results in an abnormal beta-dystroglycan protein, impacting cell interactions.
Area of Science:
- Cell Biology
- Biochemistry
- Cancer Research
Background:
- Dystroglycan is a vital receptor mediating cell adhesion and communication.
- It links the extracellular matrix to the intracellular cytoskeleton.
- Dysfunctional dystroglycan is implicated in various diseases.
Purpose of the Study:
- To investigate the integrity of dystroglycan in different cell types, particularly in cancer.
- To identify potential alterations in dystroglycan structure and expression in malignant cells.
Main Methods:
- Western blotting to detect beta-dystroglycan protein.
- Analysis of protein extracts from normal and cancerous cell lines (human and murine).
- Reverse transcriptase polymerase chain reaction (RT-PCR) to assess gene expression and splicing.
Main Results:
- Normal cells exhibited a 43 kDa beta-dystroglycan band, while cancer cells showed an anomalous ~31 kDa band.
- Alpha-dystroglycan was undetectable in most cell lines with the truncated beta-dystroglycan.
- Truncated beta-dystroglycan was also observed in chemically induced rat mammary tumors.
- RT-PCR confirmed no alternative splicing or novel isoforms were responsible for the truncated form.
- Both 43 kDa and ~31 kDa beta-dystroglycan forms contain their transmembrane segment.
Conclusions:
- Dystroglycan undergoes truncation in various human cancer cell lines and in induced rat mammary tumors.
- This truncation affects both alpha- and beta-dystroglycan subunits.
- The findings suggest a novel mechanism of dystroglycan dysfunction in cancer development.