Differential expression of IGF-1 mRNA isoforms in colorectal carcinoma and normal colon tissue

  • Authors:
    • Aldona Kasprzak
    • Witold Szaflarski
    • Jacek Szmeja
    • Małgorzata  Andrzejewska
    • Wiesława Przybyszewska
    • Elżbieta Kaczmarek
    • Maria Koczorowska
    • Tomasz Kościński
    • Maciej Zabel
    • Michał Drews
  • View Affiliations

  • Published online on: November 19, 2012     https://doi.org/10.3892/ijo.2012.1706
  • Pages: 305-316
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Abstract

The insulin-like growth factor (IGF)-1 gene consists of 6 exons resulting in the expression of 6 variant forms of mRNA (IA, IB, IC, IIA, IIB and IIC) due to an alternative splicing. The mechanisms of IGF-1 gene splicing and the role of local expression manifested by IGF-1 mRNA variants in colorectal carcinoma (CRC) have not been extensively investigated. Therefore, the aim of our study was to analyse the expression of IGF-1 mRNA isoforms [A, B, C, P1 (class I) and P2 (class II)], as well as the protein expression in CRC and control samples isolated from 28 patients. The expression of Ki-67 was also analysed and clinical data were obtained. For this purpose, we used quantitative real-time PCR (qPCR) and immunocytochemistry. The expression of mRNAs coding for all splicing isoforms of IGF-1 was observed in every tissue sample studied, with a significantly lower expression noted in the CRC as compared to the control samples. The cytoplasmic expression of IGF-1 protein was found in 50% of the CRC and in ~40% of the non-tumor tissues; however, no significant quantitative inter-group differences were observed. The expression of the IGF-1 gene in the 2 groups of tissues was controlled by the P1 and P2 promoters in a similar manner. No significant differences were detected in the expression of the IGF-1 A and B isoforms; however, their expression was significantly higher compared to that of isoform C. No significant differences were observed between the expression of Ki-67 mRNA in the CRC and control tissue even though the expression of the Ki-67 protein was higher in the CRC compared to the control samples. Ki-67 protein expression was associated with the macroscopic and microscopic aspects of CRC. A significant positive correlation was found between the local production of total mRNA and isoform A and the expression of Ki-67 mRNA, although only in the non-tumor tissues. In CRC samples, the local expression of the total IGF-1 mRNA and all splicing isoforms of IGF-1 mRNA decreased as compared to the normal colon tissues, although however, with conservation of both gene promoter activities and with the continued principal splicing IGF-1 mRNA isoforms.

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January 2013
Volume 42 Issue 1

Print ISSN: 1019-6439
Online ISSN:1791-2423

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Spandidos Publications style
Kasprzak A, Szaflarski W, Szmeja J, Andrzejewska M, Przybyszewska W, Kaczmarek E, Koczorowska M, Kościński T, Zabel M, Drews M, Drews M, et al: Differential expression of IGF-1 mRNA isoforms in colorectal carcinoma and normal colon tissue. Int J Oncol 42: 305-316, 2013.
APA
Kasprzak, A., Szaflarski, W., Szmeja, J., Andrzejewska, M., Przybyszewska, W., Kaczmarek, E. ... Drews, M. (2013). Differential expression of IGF-1 mRNA isoforms in colorectal carcinoma and normal colon tissue. International Journal of Oncology, 42, 305-316. https://doi.org/10.3892/ijo.2012.1706
MLA
Kasprzak, A., Szaflarski, W., Szmeja, J., Andrzejewska, M., Przybyszewska, W., Kaczmarek, E., Koczorowska, M., Kościński, T., Zabel, M., Drews, M."Differential expression of IGF-1 mRNA isoforms in colorectal carcinoma and normal colon tissue". International Journal of Oncology 42.1 (2013): 305-316.
Chicago
Kasprzak, A., Szaflarski, W., Szmeja, J., Andrzejewska, M., Przybyszewska, W., Kaczmarek, E., Koczorowska, M., Kościński, T., Zabel, M., Drews, M."Differential expression of IGF-1 mRNA isoforms in colorectal carcinoma and normal colon tissue". International Journal of Oncology 42, no. 1 (2013): 305-316. https://doi.org/10.3892/ijo.2012.1706