Molecular Cancer Therapeutics最新文献

The B-cell lymphoma 6 (BCL6) transcription factor plays a key role in establishment of germinal center (GC) formation. Diffuse large B cell lymphoma (DLBCL) originates from the GC reaction due to dysregulation of BCL6. Disrupting BCL6 and its corepressors interaction has become the foundation for rationally designing lymphoma therapies. However, BCL6 inhibitors with good activities in vitro and in vivo are rare and there are no clinically approved BCL6 inhibitors. Here, we discovered and developed a novel range of [1,2,4] triazolo[1,5-a] pyrimidine derivatives targeting BCL6/SMRT interaction. The analogue WK692 directly bound BCL6BTB, disrupted BCL6BTB/SMRT interaction and activated the expression of BCL6 downstream genes inside cells, inhibited DLBCL growth and induced apoptosis in vitro, inhibited GC formation, decreased proportion of follicular helper T (Tfh) cells and impaired immunoglobulin affinity maturation. Further studies showed that WK692 inhibited the DLBCL growth without toxic effects in vivo and synergizes with the EZH2 and PRMT5 inhibitors. Our results demonstrated that WK692 as a BCL6 inhibitor may be developed as a novel potential anticancer agent against DLBCL.

While heightened intratumoral levels of reactive oxygen species (ROS) are typically associated with a suppressive tumor microenvironment, under certain conditions ROS contribute to tumor elimination. Treatment approaches, including some chemotherapy and radiation protocols, increase cancer cell ROS levels that influence their mechanism of cell death and subsequent recognition by the immune system. Furthermore, activated myeloid cells rapidly generate ROS upon encounter with pathogens or infected cells to eliminate disease, and recently, this effector function has been noted in cancer contexts as well. Collectively, ROS-induced cancer cell death may help initiate adaptive anti-tumor immune responses that could synergize with current approved immunotherapies, for improved control of solid tumors. In this work, we explore the use of glucose oxidase, an enzyme which produces hydrogen peroxide, a type of ROS, to therapeutically mimic the endogenous oxidative burst from myeloid cells to promote antigen generation within the tumor microenvironment. We engineer the enzyme to target pan-tumor expressed integrins both as a tumor-agnostic therapeutic approach, but also as a strategy to prolong local enzyme activity following intratumoral administration. We found the targeted enzyme potently induced cancer cell death and enhanced cross-presentation by dendritic cells in vitro, and further combined with interferon alpha for long-term tumor control in murine MC38 tumors in vivo. Optimizing the single-dose administration of this enzyme overcomes limitations with immunogenicity noted for other pro-oxidant enzyme approaches. Overall, our results suggest ROS-induced cell death can be harnessed for tumor control, and highlight the potential use of designed enzyme therapies alongside immunotherapy against cancer.

Acute myeloid leukemia (AML) is a hematological malignancy with limited treatment options and a high likelihood of recurrence after chemotherapy. We studied N-myristoylation, the myristate modification of proteins linked to survival signaling and metabolism, as a potential therapeutic target for AML. N-myristoylation is catalyzed by two N-myristoyltransferases (NMTs), NMT1 and NMT2, with varying expressions in AML cell lines and patient samples. We identified NMT2 expression as a marker for AML patient survival, and low NMT2 expression was associated with poor outcomes. We used the first-in-class pan-NMT inhibitor, zelenirstat, to investigate the role of N-myristoylation in AML. Zelenirstat effectively inhibits myristoylation in AML cell lines and patient samples, leading to degradation of Src family kinases (SFKs), induction of endoplasmic reticulum (ER) stress, apoptosis, and cell death. Zelenirstat was well tolerated in vivo and reduced the leukemic burden in an ectopic AML cell line and in multiple orthotopic AML patient-derived xenograft models. The leukemia stem cell (LSC)-enriched fractions of the hierarchical OCI-AML22 model were highly sensitive to myristoylation inhibition. Zelenirstat also impairs mitochondrial complex I and oxidative phosphorylation, which are critical for LSC survival. These findings suggest that targeting N-myristoylation with zelenirstat represents a novel therapeutic approach for AML, with promise in patients with currently poor outcomes.

Identifying an optimal antigen for targeted cancer therapy is challenging as the antigen landscape on cancerous tissues mimics that of healthy tissues, with few unique tumor-specific antigens identified in individual patients. pH low insertion peptides (pHLIPs) act as a unique delivery platform that can specifically target the acidic microenvironment of tumors, sparing healthy tissue in the process. We developed a pHLIP-peptide conjugate to deliver the SIINFEKL peptide, an immunogenic fragment of ovalbumin, to tumor cells in vivo. When processed intracellularly, SIINFEKL is presented for immune recognition through the major histocompatibility complex (MHC) class I pathway. We observed selective delivery of pHLIP-SIINFEKL both in vitro and in vivo using fluorescently labeled constructs. In vitro, treatment of melanoma tumor cells with pHLIP-SIINFEKL resulted in recognition by SIINFEKL-specific T cells (OT1), leading to T cell activation and effector function. Mechanistically, we show that this recognition by OT1 cells was abrogated by siRNA/shRNA knockdown of multiple components within the MHC class I pathway in the target tumor cells, indicating that an intact antigen processing pathway in the cancer cells is necessary to mediate the effect of pHLIP-directed SIINFEKL delivery. In vivo, pHLIP-SIINFEKL treatment of tumor-bearing mice resulted in recruitment of OT1 T cells and suppression of tumor growth in two syngeneic tumor models in immunocompetent mice, with no effect when mutating either the pHLIP or SIINFEKL components of the conjugate. These results suggest that pHLIP-mediated peptide delivery can be used to deliver novel artificial antigens that can be targeted by cell-based therapies.

Colorectal cancer is the second leading cause of cancer mortality in the US. Although immune checkpoint blockade therapies including anti-PD-1/PD-L1 have been successful in treating a subset of colorectal cancer patients, response rates remain low. We have found that riluzole, a well-tolerated FDA-approved oral medicine for treating amyotrophic lateral sclerosis, increased intratumoral CD8+ T cells and suppressed tumor growth of colon cancer cells in syngeneic immune competent mice. Riluzole-mediated tumor suppression was dependent on the presence of CD8+ T cells. Riluzole activates the cytosolic DNA sensing cGAS/STING pathway in colon cancer cells, resulting in increased expression of interferon β (IFNβ) and IFNβ-regulated genes including CXCL10. Inhibition of ATM, but not ATR, resulted in a synergistic increase in IFNβ expression, suggesting that riluzole induces ATM-mediated damage response that contribute to cGAS/STING activation. Depletion of cGAS or STING significantly attenuated riluzole-induced expression of IFNβ and CXCL10 as well as increase of intratumoral CD8+ T cells and suppression of tumor growth. These results indicate that riluzole-mediated tumor infiltration of CD8+ T cells and attenuation of tumor growth is dependent on tumor cell intrinsic STING activation. To determine whether riluzole treatment primes the tumor microenvironment for immune checkpoint modulation, riluzole was combined with anti-PD-1 treatment. This combination showed greater efficacy than either single agent, and strongly suppressed tumor growth in vivo. Taken together, our studies indicate that riluzole activates cGAS/STING-mediated innate immune responses, which might be exploited to sensitize colorectal tumors to anti-PD-1/PD-L1 therapies. .

Over the past two decades, the "hallmarks of cancer" have revolutionized cancer research and highlighted the crucial roles of inflammation and immunity. Pro-tumorigenic inflammation promotes cancer development along with inhibition of anti-tumor immunity, shaping the tumor microenvironment (TME) towards a tumor-permissive state and further enhancing the malignant potential of cancer cells. This immunosuppressive TME allows tumors to evade immunosurveillance. Thus, understanding the complex interplay between tumors and the immune system within the TME has become pivotal, especially with the advent of immunotherapy. Although immunotherapy has achieved notable success in many malignancies, primary liver cancer, particularly hepatocellular carcinoma (HCC), presents unique challenges. The hepatic immunosuppressive environment poses obstacles to the effectiveness of immunotherapy, along with high mortality rates and limited treatment options for patients with liver cancer. In this review, we discuss current understanding of the complex immune-mediated mechanisms underlying liver neoplasms, focusing on HCC and liver metastases. We describe the molecular and cellular heterogeneity within the TME, highlighting how this presents unique challenges and opportunities for immunotherapy in liver cancers. By unraveling the immune landscape of liver neoplasms, this review aims to contribute to the development of more effective therapeutic interventions, ultimately improving clinical outcomes for patients with liver cancer.

The liver is an immune tolerant organ, allowing for organ transplantation with less immune suppression compared to other organs. It also provides fertile soil for tumor metastases, which tend to be more resistant to checkpoint blockade immunotherapy than metastases in other organs. This resistance may result from the sum of incremental evolutionary adaptions in various cell types to prevent overaction to antigens absorbed from the gut into the portal circulation or it might involve a central mechanism. Here we propose that metabolism of vitamin A, which is highly concentrated in the liver, is a root source of tolerance and resistance of hepatic metastases to checkpoint blockade. Suppression of retinoic acid synthesis from vitamin A with disulfiram may mitigate tolerance and produce enhanced immunotherapy treatment results for patients with liver metastases.

Endocrine therapies (ET) with cyclin-dependent kinase 4/6 (CDK4/6) inhibition are the standard treatment for estrogen receptor-α-positive (ER+) breast cancer, however drug resistance is common. In this study, proteogenomic analyses of patient-derived xenografts (PDXs) from patients with 22 ER+ breast cancer demonstrated that protein kinase, membrane-associated tyrosine/threonine one (PKMYT1), a WEE1 homolog, is estradiol (E2) regulated in E2-dependent PDXs and constitutively expressed when growth is E2-independent. In clinical samples, high PKMYT1 mRNA levels associated with resistance to both ET and CDK4/6 inhibition. The PKMYT1 inhibitor lunresertib (RP-6306) with gemcitabine selectively and synergistically reduced the viability of ET and palbociclib-resistant ER+ breast cancer cells without functional p53. In vitro the combination increased DNA damage and apoptosis. In palbociclib-resistant, TP53 mutant PDX-derived organoids and PDXs, RP-6306 with low-dose gemcitabine induced greater tumor volume reduction compared to treatment with either single agent. Our study demonstrates the clinical potential of RP-6306 in combination with gemcitabine for ET and CDK4/6 inhibitor resistant TP53 mutant ER+ breast cancer.

M2-like macrophages exhibit immunosuppressive activity and promote pancreatic cancer progression. Reactive oxygen species (ROS) affect macrophage polarization; however, the mechanism remains unclear. This study aimed to elucidate the underlying molecular basis and design a gene therapy to inhibit M2-like polarization. Microarray analysis and immunofluorescence staining were performed in M1-like and M2-like macrophages to ascertain the expression of CYBB, a major intracellular ROS source. Coculture assay and syngeneic orthotopic pancreatic cancer mice models were used to study the mechanism of M2-like skewing. Decoy oligodeoxynucleotides (ODNs) were designed to manipulate CYBB transcription to inhibit M2-like polarization and control tumor growth. Lipopolysaccharide treatment polarized U937 cells to M1-like macrophages in which CYBB expression was increased. In contrast, coculture with PANC-1 cells induced M2-like polarization in U937 cells with CYBB downregulation. High CD204 M2-like expression in combination with low CYBB expression was associated with the worst prognosis in patients with pancreatic cancer. STAT6 and HDAC2 in U937 cells were activated by cancer cell-derived IL4 after coculture and then bound to the CYBB promoter to repress CYBB expression, resulting in M2-like polarization. Diphenyleneiodonium, 8λ³-iodatricyclo[7.4.0.02,⁷]trideca-1(13),2,4,6,9,11-hexaen-8-ylium chloride that inhibits ROS production could block this action. Knockdown of STAT6 and HDAC2 also inhibited M2-like polarization and maintained the M1-like phenotype of U937 cells after coculture. Decoy ODNs interrupting the binding of STAT6 to the CYBB promoter counteracted M2-like polarization and tumor growth and triggered antitumor immunity in vivo. Gene therapy using STAT6-CYBB decoy ODNs can inhibit M2-like polarization, representing a potential therapeutic tool for pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is associated with significant morbidity and mortality and is projected to be the second leading cause of cancer-related deaths by 2030. Mutations in KRAS are found in the vast majority of PDAC cases and plays an important role in the development of the disease. KRAS drives tumor cell proliferation and survival through activating the MAPK pathway to drive cell cycle progression and to lead to MYC-driven cellular programs. Moreover, activated KRAS promotes a protumorigenic microenvironment through forming a desmoplastic stroma and by impairing antitumor immunity. Secretion of granulocyte-macrophage colony-stimulating factor and recruitment of myeloid-derived suppressor cells and protumorigenic macrophages results in an immunosuppressive environment while secretion of secrete sonic hedgehog and TGFβ drive fibroblastic features characteristic of PDAC. Recent development of several small molecules to directly target KRAS marks an important milestone in precision medicine. Many molecules show promise in preclinical models of PDAC and in early phase clinical trials. In this review, we discuss the underlying cell intrinsic and extrinsic roles of KRAS in PDAC tumorigenesis, the pharmacologic development of KRAS inhibition, and therapeutic strategies to target KRAS in PDAC.