Figure 4
Alternative splicing of SCN8A exon 18 in the neoplasia-carcinoma sequence of human cervical tissue. (A) Alternative splicing of SCN8A Exon 18. Expanded genomic structure of exons 17 to 19. Exon 18 N contains an in frame stop codon. Splice variants generated by alternative splicing of Exon 18 are indicated with the PCR product length expected by using primers located in Exons 17 and 19 (see Methods). (B–E) End-point PCR electrophoresis results for SCN8A exon 18 variants expressed in non-cancerous cervix, cervical intraepithelial neoplasia, invasive cervical cancer, and cervical cancer cell lines, respectively. HEK-Nav1.6 cells was used as positive control for the adult splice form of SCN8A (18A; far-right line). A 100-bp molecular weight marker was used as reference (far-left line). The SCN8A variants generated for alternative splicing of exon 18: 18A, 18N and Δ18, were identified in the indicated group of samples. Identity of the SCN8A splice forms was confirmed by automated sequencing. The SCN8A splice forms were relatively more abundant in human cervical cancer samples, more clearly for the Δ18 variant; whereas the adult (18A) variant was practically absent in CeCa cell lines. From the two samples (266 and 275) that were present in all western blots experiments, only mRNA from sample 266 was available for performing these PCR analysis.
