Impact of Oncogenic Changes in p53 and KRAS on Macropinocytosis and Ferroptosis in Colon Cancer Cells and Anticancer Efficacy of Niclosamide with Differential Effects on These Two Processes.

Mutations in p53 and KRAS are seen in most cases of colon cancer. The impact of these mutations on signaling pathways related to cancer growth has been studied in depth, but relatively less is known on their effects on amino acid transporters in cancer cells. This represents a significant knowledge gap because amino acid nutrition in cancer cells profoundly influences macropinocytosis and ferroptosis, two processes with opposing effects on tumor growth. Here, we used isogenic colon cancer cell lines to investigate the effects of p53 deletion and KRAS activation on two amino acid transporters relevant to macropinocytosis (SLC38A5) and ferroptosis (SLC7A11). Our studies show that the predominant effect of p53 deletion is to induce SLC7A11 with the resultant potentiation of antioxidant machinery and protection of cancer cells from ferroptosis, whereas KRAS activation induces not only SLC7A11 but also SLC38A5, thus offering protection from ferroptosis as well as improving amino acid nutrition in cancer cells via accelerated macropinocytosis. Niclosamide, an FDA-approved anti-helminthic, blocks the functions of SLC7A11 and SLC38A5, thus inducing ferroptosis and suppressing macropinocytosis, with the resultant effective reversal of tumor-promoting actions of oncogenic changes in p53 and KRAS. These findings underscore the potential of this drug in colon cancer treatment.

p53 mutation and deletion contribute to tumor immune evasion.

TP53 (or p53) is widely accepted to be a tumor suppressor. Upon various cellular stresses, p53 mediates cell cycle arrest and apoptosis to maintain genomic stability. p53 is also discovered to suppress tumor growth through regulating metabolism and ferroptosis. However, p53 is always lost or mutated in human and the loss or mutation of p53 is related to a high risk of tumors. Although the link between p53 and cancer has been well established, how the different p53 status of tumor cells help themselves evade immune response remains largely elusive. Understanding the molecular mechanisms of different status of p53 and tumor immune evasion can help optimize the currently used therapies. In this context, we discussed the how the antigen presentation and tumor antigen expression mode altered and described how the tumor cells shape a suppressive tumor immune microenvironment to facilitate its proliferation and metastasis.

Novel Murine Pancreatic Tumor Model Demonstrates Immunotherapeutic Control of Tumor Progression by a Toxoplasma gondii Protein.

Pancreatic ductal adenocarcinoma is the fourth leading cause of cancer-related death in the United States, with few effective treatments available and only 10% of those diagnosed surviving 5 years. Although immunotherapeutics is a growing field of study in cancer biology, there has been little progress in its use for the treatment of pancreatic cancer. Pancreatic cancer is considered a nonimmunogenic tumor because the tumor microenvironment does not easily allow for the immune system, even when stimulated, to attack the cancer. Infection with the protozoan parasite Toxoplasma gondii has been shown to enhance the immune response to clear cancer tumors. A subset of T. gondii proteins called soluble Toxoplasma antigen (STAg) contains an immunodominant protein called profilin. Both STAg and profilin have been shown to stimulate an immune response that reduces viral, bacterial, and parasitic burdens. Here, we use STAg and profilin to treat pancreatic cancer in a KPC mouse-derived allograft murine model. These mice exhibit pancreatic cancer with both Kras and P53 mutations as subcutaneous tumors. Pancreatic cancer tumors in C57BL/6J mice with a wild-type background showed a significant response to treatment with either profilin or STAg, exhibiting a decrease in tumor volume accompanied by an influx of CD4+ and CD8+ T cells into the tumors. Both IFN-γ-/- mice and Batf3-/- mice, which lack conventional dendritic cells, failed to show significant decreases in tumor volumes when treated. These results indicate that gamma interferon (IFN-γ) and dendritic cells may play critical roles in the immune response necessary to treat pancreatic cancer.

p53 Deletion promotes myeloma cells invasion by upregulating miR19a/CXCR5.

P53 deletion has been identified as one of the few factors that defined high risk and poor prognosis in MM. It has been reported p53 deletion is associated with resistance to chemotherapy and organ infiltrations of MM. However, p53 deletion in the migration and dissemination of MM cells has not been totally elucidated. In this research, first, we investigated whether p53 is associated with migration of MM cells. We found that p53 regulates the migration of NCI-H929 cells with wild-type p53 but not U266 cells with mutated-type p53. Next, we investigated the related mechanism by which p53 regulates the migration. We found that down-regulation of p53 reduced adhesion of NCI-H929 cells to the BM stroma via decreased expression of E-cadherin and increased EMT-regulating proteins. Further study have identified the miR-19a/CXCR5 pathway as a candidate p53-induced migration mechanism. In conclusion, we have demonstrated for the first time the critical value of p53 deletion in MM cell migration and dissemination, as well as the acquisition of an EMT-like phenotype. Our research provides new insights into the function of p53 in migration of MM and suggests p53/miRNA19a/CXCR5 may provide potentially therapeutic targets for the treatment of myeloma with p53 deletion.

FXR1 regulates transcription and is required for growth of human cancer cells with TP53/FXR2 homozygous deletion.

Tumor suppressor p53 prevents cell transformation by inducing apoptosis and other responses. Homozygous TP53 deletion occurs in various types of human cancers for which no therapeutic strategies have yet been reported. TCGA database analysis shows that the TP53 homozygous deletion locus mostly exhibits co-deletion of the neighboring gene FXR2, which belongs to the Fragile X gene family. Here, we demonstrate that inhibition of the remaining family member FXR1 selectively blocks cell proliferation in human cancer cells containing homozygous deletion of both TP53 and FXR2 in a collateral lethality manner. Mechanistically, in addition to its RNA-binding function, FXR1 recruits transcription factor STAT1 or STAT3 to gene promoters at the chromatin interface and regulates transcription thus, at least partially, mediating cell proliferation. Our study anticipates that inhibition of FXR1 is a potential therapeutic approach to targeting human cancers harboring TP53 homozygous deletion.

Biallelic ATM alterations detected at diagnosis identify a subset of treatment-naïve chronic lymphocytic leukemia patients with reduced overall survival similar to patients with p53 deletion.

The prognostic impact of biallelic ATM abnormalities (ATM mutation and concurrent 11q deletion) remains unknown. We studied ATM, BIRC3, SF3B1, and NOTCH1 genes in 118 treatment-naïve CLL patients at diagnosis. Patients with biallelic ATM alteration had a similar time to first treatment (TTFT) and shorter overall survival (OS) compared with patients with isolated 11q deletion and shorter TTFT and OS when compared to patients with wild-type ATM. Furthermore, biallelic ATM alteration (HR: 6.4; p ≤ 0.007) was significantly associated with an increased risk of death similar to p53 deletion (HR: 6.1; p ≤ 0.004), superior to 11q deletion alone (HR: 2.8; p ≤ 0.022) and independent of other significant parameters such as age, advanced clinical stage, and complex karyotype. Our results suggest the identification of ATM mutations in CLL patients with 11q deletion at diagnosis is clinically relevant and predicts disease progression, poor response to the treatment, and reduced OS independent of other molecular prognostic factors.

Features of extramedullary disease of multiple myeloma: high frequency of p53 deletion and poor survival: a retrospective single-center study of 834 cases.

BACKGROUND: Multiple myeloma (MM) is a heterogeneous disease in which most patients have myeloma restricted to the bone marrow, and some patients develop extramedullary disease (EMD) at the time of diagnosis or during follow-up, and show different clinical characteristics and a dismal prognosis. PATIENTS AND METHODS: We studied 834 consecutive MM patients in a single center in China and compared clinical features of patients with and without EMD. RESULTS: In general, the prevalence of EMD was 4.8% at the time of diagnosis and 3.4% during follow-up, with a significant increase in recent years. MM patients with EMD at the time of diagnosis had remarkably greater prevalence of P53 deletion determined using fluorescence in situ hybridization (FISH) analysis (34.5% vs. 11.9%; P = .037) and higher level of lactate dehydrogenase (LDH) (P = .003) compared with patients without EMD. EMD relapse/progression during follow-up was correlated with EMD presentation at diagnosis, immunoglobulin (Ig)D subtype and P53 deletion in FISH analysis, but not previous treatment (thalidomide, bortizomib, or transplantation). With respect to prognosis, multivariate analysis showed that EMD was an independent adverse prognostic factor. The overall survival of patients with and without EMD at diagnosis were 16.5 and 40 months, respectively (P < .001), and the time to disease progression of the 2 groups was 11.5 and 25 months, respectively (P < .001). CONCLUSION: MM patients with EMD at the time of diagnosis showed remarkably greater prevalence of P53 deletion in FISH analysis and higher LDH levels. EMD relapse/progression was correlated with EMD presentation at diagnosis, IgD subtype, and P53 deletion in FISH analysis, but not previous exposure to new drugs or transplantation. The presence of EMD involvement negatively affected survival.