MCT1 Transporter Inhibition of IMR90 Cells Expressing Inducible Merkel Cell Carcinoma Small T Antigen
Mentor: James A DeCaprio, MD (Dana-Farber Cancer Institute)
Polyomaviruses are a non-enveloped double stranded DNA based virus that exists in nearly the entire population in various forms. Generally, the polyomavirus genome encodes for two transcriptional proteins, small T and large T in the early region, which are formed from alternative splicing of the region, as well as structural capsid proteins. Merkel cell polyomavirus was discovered using pyrosequencing in Merkel cell carcinoma. It was discovered that this viral genome was integrated into the genome of the cancer. Furthermore, mutations and deletions in the viral genome that inhibit viral DNA replication were discovered. It has been known that cancerous cells require an influx of nutrients and biosynthetic activity in order to duplicate all the cellular components in a rapid rate. Thus metabolic rates of cancerous cells are fundamentally higher than those in normal cells. Tumor cells are also shown to exhibit a phenotype known as the Warburg effect, where the energy necessary for replication is mostly produced by a high rate of glycolysis and lactic acid fermentation in the cytoplasm rather than the oxidation of pyruvate. However, excessive use of glycolysis produces excessive amounts of lactate, which in turn reduces the pH of the surrounding environment. Recently, it has been shown that certain cells are able to uptake the lactate and use it to fuel respiration through high prevalence of the MCT1 transporter. It has also been shown that inhibiting the MCT1 transporter in cells that are suspected to intake lactate environment has been shown to exhibit apoptosis rather than glucose fueled respiration. High levels of internal lactate have been characteristically observed in Merkel cell carcinoma lines. It is suspected that one of the T antigens of the virus is able to modulate the metabolic process of a normal Merkel cell in order to induce transformation. This hypothesis will be tested in IMR90 cells that inducibly express the small T antigen in order to observe whether there is a difference in lactate concentration inside and outside the cell. The effect of α-cyano-4-hydroxycinnamate (CHC,) an MCT1 transporter inhibitor, will also be investigated. There is great promise in the medicinal properties of MCT1 transporter inhibition. It is necessary to examine its inhibition in order to explore the possibilities of alternative cancer treatment therapies.
Immunofluorescent image of ST antigen expression (green) overlaid on the nucleus (blue) of IMR90 cells. Source: DFCI Source: