Circulating tumor cells isolated from colorectal cancer patients can form spheroids spontaneously: a small study in Ciptomangunkusumo Hospital, Indonesia

Background: : Circulating Tumor Cells (CTC) are tumor cells that have been separated from the primary site and enter the blood or lymphatic circulation of cancer patients. CTCs are  known to have tumorigenic properties and are  thought to have a relationship with metastasis. One of the tests that can be used to assess tumorigenesis is the spheroid formation test. This study was conducted to determine CTCs’ ability to form spheroids. Methods: : A 1 ml sample of blood was taken from two patients with metastatic colorectal cancer and placed in separate heparin tubes. The CTCs were then isolated using the DirectCTC enrichment kit according to the manufacturer's procedure. A total of 10,000 cells were grown in nuncsphera u plates in Dulbecco’s Modified Eagle Medium (DMEM) for three days under standard culture conditions. Spheroid or aggregation was then evaluated using an inverted microscope. Results: : We identified a CTC culture derived from each of the patients with metastatic colorectal cancer, namely CTC ID001 and CTC 002 respectively. CTC ID001 formed spheroids spontaneously while CTC ID002 did not. CTC ID001 appears to aggregate spontaneously and resembles primary tumor cells in their ability to form spheroids. Conclusions: : We observed that CTCs can mimic primary tumors to form spheroids spontaneously, though some CTCs are not able to form spheroids. We suspected that this was related to the tumorigenic nature of CTC in these patients.