Genetic determinants of methotrexate responsiveness and resistance in colon cancer cells

• Published in: Oncogene Vol. 24; no. 45; pp. 6842 - 6847
• Main Authors: MORALES, Cristina, RIBAS, Maria, AIZA, Gemma, PEINADO, Miguel A
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 13.10.2005; Nature Publishing Group
• Subjects: Antimetabolites, Antineoplastic - pharmacology; Biological and medical sciences; Cancer therapies; Carcinogenesis; Cell growth; Cell Line, Tumor; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Chemoresistance; Chemotherapy; Chromosomes; Chromosomes, Human, Pair 5; Colon cancer; Colonic Neoplasms - genetics; Colonic Neoplasms - pathology; Colorectal cancer; Dihydrofolate reductase; Diploids; DNA biosynthesis; Drug resistance; Drug Resistance, Neoplasm; Enzymes; Epigenetics; Fundamental and applied biological sciences. Psychology; Gastroenterology. Liver. Pancreas. Abdomen; Gene amplification; Genes; Humans; In Situ Hybridization, Fluorescence; Karyotyping; Medical sciences; Metastases; Methotrexate; Methotrexate - pharmacology; Microsatellite instability; Molecular and cellular biology; Stomach. Duodenum. Small intestine. Colon. Rectum. Anus; Tumor cell lines; Tumors; Vitamin B; Antineoplastic agent; genetic instability; Treatment resistance; Rectal disease; Colorectal cancer; Malignant tumor; Carcinogenesis; Colonic disease; Colon cancer; tumor classification; Classification; Digestive diseases; Intestinal disease; Genetics; Instability; drug resistance; Methotrexate
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1208834

Alternative genetic pathways characterized by specific genetic profiles and exhibiting distinctive biological and clinical features have been proposed in colorectal carcinogenesis. Methotrexate (MTX) is a potent inhibitor of the dihydrofolate reductase (DHFR) enzyme, which is essential for DNA synthesis and cell growth. We have evaluated the association between different genetic features and the capacity to develop MTX resistance in colon cancer cell lines representative of alternative genetic pathways. Three aneuploid cell lines (HT-29, SW480, and SK-CO-1) showed pre-existing amplifications, but only one (HT-29) developed MTX resistance, showing amplification of the DHFR gene at 5q12-14 (>20-fold amplification and presence of extrachromosomal double minutes). Failure to develop resistance was attributed to the absence of two complete chromosomes 5 in SW480 and SK-CO-1 cells. Four near-diploid cell lines (LoVo, HCT116, DLD-1 and KM12C) and two aneuploid KM12C-derived metastases (KM12SM and KM12L4A) developed MTX resistance but none exhibited DHFR amplification. All resistant cells without DHFR gene amplification showed microsatellite instability. We conclude that chemoresistance capacity and the mechanism of chemoresistance are related with the genetic pathway and the karyotypic features of colon cancer cells.