Thyroid cancer is the most common of the endocrine cancers, with papillary thyroid carcinomas (PTCs) being the most common form. Thyroid cancer has excellent diagnostic tools, yet there are still some cases that progress post treatment and a few that are not caught at all. A group from Jeju, South Korea decided to investigate SPARC-related modular calcium-binding protein-2, or SMOC2, as a potential tool for further diagnostic tests to catch recurrence early on.
SMOC2, usually a regulator of a cell’s interaction with the surrounding environment during development or disease, has been implicated in several processes related to the progression of cancer. Using this information, the group began to measure the levels of SMOC2 expression in normal thyroid tissue versus PTC thyroid tissues.
The group began by using reverse transcription PCR to measure the mRNA encoding SMOC2 in normal thyroid tissue against several forms of thyroid cancer. They found that SMOC2 expression was lower in almost every cancer sample compared to normal thyroid samples. Next, they took a large sample size of 338 PTC samples and directly stained for SMOC2. The results, showing a significantly lower level of SMOC2 in PTC samples compared to regular thyroid samples, which concurred with the previous mRNA measurements.
Unfortunately, not every result was as clear cut. The thyroid cancer nodular hyperplasia did not follow the same trend rest of the thyroid cancers, retaining normal levels of SMOC2 expression. Follicular adenomas also failed to produce statistically significant data in SMOC2 expression testing. The group tried to investigate why SMOC2 would be down regulated in PTCs, looking at epigenetic methylation of SMOC2's DNA. The sample sized proved to be to small however, and again could not produce much statistically significant data.
The group concludes “Our findings of SMOC2 expression down-regulation in PTC and its association with improved clinical outcomes clearly suggest that SMOC2 likely acts as a tumor suppressor in thyroid cancers.”. Even though some of the results proved inconclusive, the work done here showed productive insights for the possible use of SMOC2 as a secondary biomarker in tests against thyroid cancer.
Sources: Nature, OncLive
