Glycans (carbohydrates) can substantially influence and modulate protein structure and function in multiple ways such as protein folding, conformation, stability, activity etc. which directly impact key processes supporting tumor progression and metastasis, including cell adhesion, motility, invasion, signaling activation, cell-matrix interactions, immune evasion. We are specifically interested to study that what are the precise mechanisms by which biochemical and structural changes in glycans of a glycoprotein, regulate tumor progression and metastasis and resistance to various therapies.
1. Glycosylation as a regulator of tropism of melanoma metastasis: Malignant melanoma is one of the most aggressive cancers and can disseminate from a relatively small primary tumor and metastasize to multiple sites, including the lung, liver, brain, bone, and lymph nodes. Recently, we identified that a fucosyltransferase FUT8 is a driver of melanoma metastasis (Agrawal et al., 2017). Further, we postulated that adaptation of tumor cells to distinct secondary sites requires specific changes in cell surface glycosylation. To explore this idea and identifying glycan epitopes and glycogenes involved in site specific organ tropism of melanoma, we utilize multiple approaches such as glycomics and glycogenomics of in vivo melanoma metastasis models and clinical patient samples of melanoma. We aim to identify target glycoproteins and their mechanism of action which contributes in site-specificity of melanoma metastasis.
2. Investigation the biological role of L1CAM glycosylation in melanoma brain metastasis: Metastases to the brain are among the most clinically significant, because even a single one is likely to cause serious disability. In our previous study of melanoma, we showed that in vitro L1CAM cleavage is dependent on core fucosylation and a glycosylation site is adjacent to L1CAM cleavage site. L1CAM is known to express by metastatic cells for spreading along brain capillaries and for metastatic outgrowth. Currently, we are testing if modulation of glycosylation site/s affects L1CAM cleavage, protein-protein interactions, and brain metastasis capability using various biochemical approaches and in vivo brain metastasis models.
3. The role of glycosylation alteration in resistance to targeted therapy of Prostate cancer: In the past years, many therapeutic advances have been achieved in castration-resistant prostate cancer (CRPC), with the approval of several new drugs such as AR inhibitors abiraterone and enzalutamide which have shown an improvement in overall survival (OS) however sooner or later acquired drug resistance appears. As glycans are active players throughout cancer development and progression, we are identifying specific changes in glycosylation required for resistance to therapy of PCa. We utilize a multi-step systems biology approach including lectin microarray (Agrawal et al., 2014) and glycan mass spectrometry based glycomics, glycogene data mining of PCa clinical datasets, in vivo high-throughput functional screen with a barcoded glycogene shRNA/sgRNA library and identification of glycoprotein targets using lectin-affinity pulldown and mass spectrometry. These glycoproteins will be further analyzed for role of their glycosylation status and mechanism of action in PCa targeted therapy.