Microsatellite Instability-High, Malignant Insulinoma With Brain Metastasis

PMS2 amplification contributes brain metastasis from lung cancer

BACKGROUND

Lung adenocarcinoma metastasizing to the brain results in a notable increase in patient mortality. The high incidence and its impact on survival presents a critical unmet need to develop an improved understanding of its mechanisms.

METHODS

To identify genes that drive brain metastasis of tumor cells, we collected cerebrospinal fluid samples and paired plasma samples from 114 lung adenocarcinoma patients with brain metastasis and performed 168 panel-targeted gene sequencing. We examined the biological behavior of PMS2 (PMS1 Homolog 2)-amplified lung cancer cell lines through wound healing assays and migration assays. In vivo imaging techniques are used to detect fluorescent signals that colonize the mouse brain. RNA sequencing was used to compare differentially expressed genes between PMS2 amplification and wild-type lung cancer cell lines.

RESULTS

We discovered that PMS2 amplification was a plausible candidate driver of brain metastasis. Via in vivo and in vitro assays, we validated that PMS2 amplified PC-9 and LLC lung cancer cells had strong migration and invasion capabilities. The functional pathway of PMS2 amplification of lung cancer cells is mainly enriched in thiamine, butanoate, glutathione metabolism.

CONCLUSION

Tumor cells elevated expression of PMS2 possess the capacity to augment the metastatic potential of lung cancer and establish colonies within the brain through metabolism pathways.

Malignant insulinoma: Can we predict the long-term outcomes?

Insulinomas are the most frequent type of functional pancreatic neuroendocrine tumors with a variety of neuroglycopenic and autonomic symptoms and well-defined diagnostic criteria; however, prediction of their clinical behavior and early differentiation between benign and malignant lesions remain a challenge. The comparative studies between benign and malignant cases are limited, suggesting that short clinical history, early hypoglycemia during fasting, high proinsulin, insulin, and C-peptide concentrations raise suspicion of malignancy. Indeed, malignant tumors are larger with higher mitotic count and Ki-67 proliferative activity, but there are no accurate histological criteria to distinguish benign from malignant forms. Several signaling pathways have been suggested to affect the pathophysiology and behavior of insulinomas; however, our knowledge is limited, urging a further understanding of molecular genetics. Therefore, there is a need for the identification of reliable markers of metastatic disease that could also serve as therapeutic targets in patients with malignant insulinoma. This opinion review reflects on current gaps in diagnostic and clinical aspects related to the malignant behavior of insulinoma.