Browsing by Subject "LLT1"
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Item Expression and Function of Immune Receptors in Pediatric Acute Lymphoblastic Leukemia(2016-12-01) Powers, Sheila B.; Stephen O. Mathew; Porunelloor A. Mathew; W. Paul BowmanAcute lymphoblastic leukemia (ALL) is a cancer that mainly affects children around the age of five. Due to current treatments, 80-90% of children achieve long-term remission. However, because of the current treatments, which include chemotherapy and CNS-directed radiation, these children may experience late effects which impact growth and development. Even though survival rate is high, quality of life can be greatly reduced for some of the survivors. Natural Killer (NK) cells are cells of the innate immune system that are important in fighting cancer and virally-infected cells. They have been a subject of interest in ALL because ALL of the B cell lineage is particularly resistant to NK cell killing. NK cells get activated by their surface receptors and their ligands on target cells. In B cell ALL, the NK cells do not appear to get the proper activating signals and this has been determined to be one reason this cancer is able to thrive. Our lab has cloned three immune receptors, 2B4 (CD244), CS1 (CRACC, CD319) and LLT1 (CLEC2D), that are expressed on NK cells as well as other immune cells. These receptors have been shown to play an important role in NK cell activation. Two other receptors, NKp30 and NKp46, are well-known activating receptors that have also been implicated in ALL. In this project I compared the mRNA and surface protein receptor expression of immune receptors between healthy subjects and ALL subjects. Altered expression of immune receptors was observed in ALL subjects. In particular, a significant decrease in mRNA expression of 2B4, LLT1 and NKp30 was observed in ALL subjects at diagnosis compared to healthy subjects. mRNA expression of CS1 was increased significantly after chemotherapy treatment. In contrast, NKp46 mRNA expression was significantly increased in ALL subjects as compared to healthy subjects. Cell surface protein expression of CS1 was significantly upregulated on T cells and monocytes and LLT1 on NK cells of ALL subjects at diagnosis. Interestingly, NKp30 was overexpressed on B cells, T cells, monocytes and NKp46 was overexpressed on T cells and monocytes but not on NK cells of ALL subjects at diagnosis. I also detected a significant increase of soluble CS1and BAT-3 in ALL subjects at diagnosis between the ages of 1-11 yrs. Also, soluble CD48 was significantly increased in ALL subjects after chemotherapy treatments. Future mechanistic studies may shed more light in the immune dysfunction in ALL ultimately contributing to better treatment options for patients with pediatric ALL.Item Expression and Function of Ligands for Natural Killer Cell Receptors on Triple-negative Breast Cancer Cells(2018-08) Marrufo, Armando M.; Mathew, Porunelloor A.; Mathew, Stephen O.; Jones, Harlan P.; Phillips, Nicole R.Triple-negative breast cancer (TNBC) accounts for 20 percent of all breast cancer cases and is known to be the most invasive form of breast cancer. TNBC's absence of estrogen, progesterone, and human epidermal growth factor-2 receptors makes utilizing hormonal treatments ineffective in suppressing tumor growth. TNBC is associated with poorer prognosis and higher incidences of relapse. Therefore, natural killer cell-mediated immunotherapy shows potential as a treatment option for TNBC. Natural killer cells (NK) are innate lymphoid cells that serves its role in the immune system to eradicate infected and tumor cells. NK cell function is regulated through its receptors interacting with activating and inhibitory ligands on target cells. Lectin-like Transcript-1 (LLT1, CLEC2D) is a ligand that interacts with NKRP1A (CD161) and inhibits NK cell activation. Proliferating Cell Nuclear Antigen (PCNA) is a ligand that interacts with NKp44 and inhibits NK cell activation. We have identified the expression and function of LLT1 and PCNA on TNBC cell lines by flow cytometry, western blot, immunofluorescent microscopy, and chromium-release assay. Our results have demonstrated a higher expression of LLT1 and PCNA on TNBCs than non-tumorigenic breast cell line MCF10A. We have shown that blocking LLT1 interaction with NKRP1A with antibodies and gene knockdown of LLT1, respectively, on TNBCs have increased lysis of TNBCs by primary NK cells. We have also shown that blocking PCNA interaction with NKp44 with antibodies have enhanced killing of TNBCs by NK cells. LLT1 and PCNA expressed on TNBCs sends an inhibitory signal to the NK cell thus serving its role for TNBCs to evade immunosurveillance. Blocking LLT1-NKRP1A or PCNA-NKp44 with antibodies enhances lysis by NK cells and may open a novel immunotherapeutic strategy for patients diagnosed with TNBC.Item The Role of LLT1 (CLEC2D, OCIL) in Ewing Sarcoma(2021-12) Buller, Casey W.; Mathew, Stephen O.; Mathew, Porunelloor A.; Jones, Harlan P.; Basha, Riyaz; Tovar-Vidales, TaraEwing Sarcoma (EWS) is a pediatric bone cancer that is characterized by a chromosomal translocation giving rise to a neomorphic gene fusion. Although treatment of EWS has a 5-year incident free survival rate of 66%, treatment has plateaued since the 1980's. Natural killer (NK) cells are an important innate immune cell due to their ability to recognize and lyse virally infected and cancerous cells. Unfortunately, cancerous cells often employ strategies such as the downregulation of major histocompatibility complex (MHC) I, or upregulation of inhibitory ligands enabling the escape of T-cells and NK cell mediated killing. LLT1 is an inhibitory ligand our lab had previously shown that it is expressed on TNBC and prostate cancer cell lines. The expression of LLT1 and its function in Ewing Sarcoma (EWS) cell lines has yet to be performed. Our hypothesis is that LLT1 is increased in EWS cell lines TC-32 and CHLA-258 when treated with chemotherapeutic drugs vincristine and etoposide. Our results show that LLT1 is expressed on EWS cell lines and inhibition of LLT1 increases NK cell cytotoxicity. These results indicate that LLT1 is a potential immunotherapy target that needs to be further evaluated in an in vivo model.