Molecular Cancer Therapeutics最新文献

Solute carrier family 16 member 2 (SLC16A2), also known as monocarboxylate transporter 8 (MCT8), is a member of the SLC16 family that exerts essential functions in the transport of elemental cell nutrients. This study explores the function of SLC16A2 in hepatocellular carcinoma (HCC) progression, particularly its impact on T-cell function. We established Slc16a2 gene knockout (Slc16a2ko) C57BL/6 mice and injected H22 cells subcutaneously to analyze tumor growth and T-cell activity in vivo. Additionally, Slc16a2fl/fl mice were crossed with Cd8aCre mice to obtain Slc16a2-Cd8a-ko mice, in which Slc16a2 was specifically knocked out in CD8+ T cells. In addition to subcutaneous models, luciferase-labeled H22 cells were injected into the liver lobe of mice for orthotopic models. SLC16A2 alteration did not affect the proliferation or migration of mouse Hepa1-6 and H22 cells in vitro though the tumorigenic activity of H22 cells was substantially reduced in Slc16a2ko and Slc16a2-Cd8a-ko C57BL/6 mice. Slc6a2 was highly expressed in exhausted T (Tex) cells, and its expression in Tex cells, as well as the population of Tex cells in tumors, was increased by lactate or other chronic stimuli. An MCT8 monoclonal antibody (mAb) reduced lactate uptake by Tex cells, thus enhancing CD8+ T-cell activity and reducing tumor growth in mice. The MCT8 mAb treatment also enhanced the efficacy of anti-PD-L1 in mice bearing tumors. This study supports that SLC16A2 contributes to Tex cell accumulation in association with increased lactate uptake and hampers immune activity in HCC, supporting SLC16A2 as a promising target to enhance immune activity in HCC management.

We previously used a myoblast model of fusion-positive rhabdomyosarcoma (FP-RMS) to show that FGF8, a PAX3-FOXO1 (P3F) transcriptional target, is required for P3F-driven tumorigenicity and, when aberrantly expressed, can maintain tumorigenicity in P3F-independent recurrent tumors. We report in this study that FGF8, FGFR1, and FGFR4 are often highly expressed in FP-RMS tumors. High FGF8 expression in FP-RMS cells is associated with high sensitivity to an FGFR4 inhibitor and a pan-FGFR inhibitor. Although downregulating FGF8 resulted in loss of sensitivity to these inhibitors, FGF8 upregulation in myoblasts decreased FGFR4 expression and sensitized the cells to an FGFR1 inhibitor and a pan-FGFR inhibitor. FGF8 downregulation of FGFR4 expression was reverted by inhibitors of FGFR1, MEK, or ERK, thus defining a signaling pathway by which FGF8 mediates this regulatory effect. Finally, high FGF8 expression in P3F-independent recurrent tumors was attributable to a rearrangement of viral long terminal repeat (LTR) sequences into the FGF8 3' untranslated region, resulting in increased FGF8 mRNA stability. These findings indicate that FGF8 exerts oncogenic effects in FP-RMS via FGFR4 and may exert oncogenic effects in P3F-independent relapses via FGFR1. Our study reveals the functional significance of FGF8 in FP-RMS and provides a rationale for preclinical studies of FGFR inhibitors in FP-RMS.

Endocrine therapy has proven to be beneficial for patients with estrogen receptor (ER) positive, HER2 negative (ER+/HER2-) breast cancer; however, de novo or acquired resistance remains a major clinical challenge. Upon progression, many of the cancers continue to be ER dependent, highlighting the opportunities for novel ER targeting therapies. Fulvestrant, a selective estrogen receptor degrader (SERD) that antagonizes and degrades ER simultaneously, has demonstrated activity in ER+/HER2- breast cancers the ability to overcome endocrine resistance. Fulvestrant has limitations including challenging administration by intramuscular injection and poor bioavailability, resulting in sub-optimal drug exposure, hence several next generation oral SERDs with improved drug properties have been developed and are currently being evaluated in the clinic for their therapeutic benefit. Here, we describe the discovery of ZN-c5, an orally bioavailable SERD with favorable pharmacokinetic properties and potent activities against both wild-type and mutant ER. In vivo studies showed that ZN-c5 treatment resulted in significant tumor growth inhibition in a variety of breast cancer models and patient-derived xenograft models that harbor ESR1 mutations. Combination with CDK4/6 inhibitors or PI3K pathway inhibition enhanced anti-tumor effects compared with single agent alone. ZN-c5 also demonstrated bone protective effect as observed in a mouse osteoporosis model. These data support the clinical utility of ZN-c5 as monotherapy and as a combination therapy for patients with ER+/HER2- breast cancers. While encouraging plasma exposure and tolerability have been observed for ZN-c5 in patients, further studies are needed to optimize its therapeutic efficacy.

The Methyl CpG Binding Protein 2 (MECP2) gene has copy number gain in a number of human cancers and functions as an oncogene through an unusual epigenetic mechanism. We explored the possibility that MECP2 might be a therapeutic target, and whether its epigenetic mode of action is amenable to specific therapy. Constitutively expressed or inducible lentiviral short hairpin RNA (shRNA) directed at MECP2 in human triple negative breast cancer (TNBC) cell lines with high or low level of MECP2 protein were grown as xenografts to assess oncogene addiction. We next evaluated the effect of DNA methylation inhibitors or histone deacetylase inhibitors on monolayer or soft agar growth of isogenic human mammary epithelial cells with or without MECP2 overexpression, and xenograft growth of MECP2-dependent or MECP2-independent human TNBC or lung cancer cell lines. We then investigated the mechanism of MECP2-induced activation of MAPK pathway and assessed the effect of drug treatment. Human cancer cell lines with MECP2 overexpression show MECP2 dependence, and epigenetic drugs are effective in these models. Activated RAS and other activators of the MAPK pathway caused resistance to these therapies, giving insight into their novel mode of action and demonstrating specificity. The kinase PAK3 is important for MECP2-mediated induction of MAPK pathway, is modulated by epigenetic drugs affecting MECP2 action as expected and may itself be a therapeutic target for MECP2-driven cancers. These preclinical studies show that tumors overexpressing MECP2 might benefit from epigenetic therapy targeting MECP2 function and demonstrate a novel mechanism of action for these drugs.

Investigating the mechanisms of acquired resistance to antiandrogens remains a critical clinical need as patients with prostate cancer inevitably develop resistance to androgen receptor (AR)-targeted therapies. Previously, we demonstrated that neuregulin 1 (NRG1) derived from cancer-associated fibroblasts (CAFs) promotes antiandrogen resistance through HER3-AKT signaling. Here, we sought to further dissect the molecular context in which NRG1-induced PI3K signaling activation plays a dominant role in driving resistance and evaluate whether targeting HER2/3 dimerization can influence sensitivity to AR inhibition. Immunohistochemical analysis of radical prostatectomy specimens from prostate cancer patients treated with or without neoadjuvant hormonal therapy shows that NRG1 was significantly upregulated following AR inhibition independent of PTEN status. However, we found that stimulation with recombinant NRG1 or CAF-conditioned media induced resistance to AR inhibition only in PTEN wild-type prostate cancer cells, and not in PTEN-deficient cells. Selective inhibition of NRG1 using the clinical-grade bispecific humanized immunoglobulin G1, zenocutuzumab (Zeno, MCLA-128), restored sensitivity to AR-targeted therapies in PTEN wild-type tumors, demonstrating its efficacy as a potential therapeutic agent to block the effects of NRG1. In the context of PTEN loss and AR inhibitor resistance, zenocutuzumab did not restore sensitivity. These findings highlight the critical molecular context in which tumor microenvironment (TME)-derived NRG1 impacts responsiveness to AR inhibition and suggest that targeting NRG1 is a promising strategy for overcoming resistance to androgen blockade in PTEN-wildtype prostate cancers.

AXL is an important negative regulator of type I IFN responses during viral infections. In the context of tumors, AXL is associated with driving tumor progression, spread, immune evasion, and therapy resistance. AXL regulation of tumor cell-intrinsic IFN responses remains unexplored. We show that AXL suppresses tumor cell-intrinsic IFN responses by inhibiting the cytosolic DNA sensor cGAS via an AKT-dependent pathway. AXL inhibition in combination with chemoimmunotherapy demonstrated potent antitumor effects in poorly immunogenic tumors that are refractory to immunotherapy. The inhibition of AXL correlated with increased cGAMP levels, activation of IFN, and enhanced infiltration of T cells and NK cells into the tumor microenvironment. These findings reveal a novel role for AXL in suppressing IFN within tumors and support AXL targeting as a promising strategy in conjunction with chemoimmunotherapy for treating therapy-resistant tumors.

Enzalutamide resistance remains a significant challenge in the treatment of advanced prostate cancer. Identifying molecular drivers of enzalutamide resistance is crucial for developing effective therapeutic strategies. In this study, we identify insulin-like growth factor binding protein 3 (IGFBP3) as a key driver of enzalutamide resistance in castration-resistant prostate cancer (CRPC). We demonstrate that IGFBP3 expression is significantly upregulated in enzalutamide-resistant C4-2B MDVR cells compared to parental C4-2B cells. This upregulation was consistently observed across multiple enzalutamide-resistant CRPC models, including LNCaP-derived 42D and 42F cells, as well as long-term enzalutamide-resistant cell lines derived from LNCaP, VCaP, LAPC-4, and CWR-R1 cells. Additionally, Enzalutamide treatment directly induced IGFBP3 expression in sensitive cells. Elevated IGFBP3 expression was also observed in CRPC patient samples post-enzalutamide treatment and was associated with higher Gleason scores and reduced disease-free survival. Mechanistically, IGFBP3 activates the sphingosine kinase 1 (SphK1)/sphingosine-1-phosphate (S1P) signaling pathway, which promotes cell survival and resistance to enzalutamide. IGFBP3 knockdown decreased SphK1 expression, reduced S1P secretion, and enhanced enzalutamide sensitivity, whereas IGFBP3 overexpression induced SphK1 expression and S1P production, conferring enzalutamide resistance. Inhibition of IGFBP3 via siRNA reduced cell viability, induced apoptosis, and re-sensitized resistant models to enzalutamide. Similarly, targeting SphK1 with the inhibitor SKI-II suppressed SphK1 activity, reduced S1P production, enhanced enzalutamide sensitivity, and significantly inhibited resistant tumor growth while enhancing enzalutamide sensitivity. Collectively, these findings highlight IGFBP3-mediated SphK1 signaling as a critical mediator of enzalutamide resistance and suggest that targeting the IGFBP3/SphK1/S1P axis represents a promising therapeutic strategy to overcome resistance in advanced prostate cancer.

Directly targeting RAS is a promising approach for the treatment of RAS-altered malignancies. Recently, several groups have developed mutation-specific agents such as sotorasib and adagrasib, which directly target KRAS by covalently modifying KRAS(G12C). KRAS is commonly altered in adult malignancies, such as lung, pancreatic, and colorectal adenocarcinomas, but is less commonly altered in pediatric cancers. However, rare pediatric solid tumors harboring K-, H-, or NRAS(G12C) have been observed, including rhabdomyosarcoma and neuroblastoma tumors as well as leukemias. The efficacy of KRAS(G12C) inhibitors in pediatric malignancies is currently unknown, and the ability of these drugs to modify H- and NRAS(G12C) has not been completely characterized. Here, we show that sotorasib, adagrasib, and the RAS-ON inhibitor RMC-6291 are effective in a neuroblastoma cell line altered by KRAS(G12C). We further demonstrated that sotorasib and adagrasib inhibited SOS-mediated guanine nucleotide exchange on H- and NRAS(G12C). Sotorasib and RMC-6291 decreased ERK phosphorylation in cells expressing H-, K-, or NRAS(G12C). Importantly, sotorasib also decreased ERK phosphorylation in a NRAS(G12C)-altered cell line xenograft model; however, this treatment did not prolong survival as a single agent. These results suggest that combinations of targeted agents that include sotorasib may be required for clinical benefit in pediatric patients with H- or NRAS(G12C)-altered malignancies in addition to those with KRAS(G12C)-altered malignancies.

Pancreatic ductal adenocarcinoma (PDAC) is the deadliest major cancer and has a profoundly immunosuppressive tumor microenvironment (TME). Previous studies have shown that inhibition of the E1 enzyme, which catalyzes the small ubiquitin-like modifiers (SUMO), with the small molecule TAK-981, can reprogram the TME to enhance immune activation and suppress tumor growth. We found that the CD-155/TIGIT pathway, a key regulator of immune evasion in PDAC, is influenced by SUMOylation. We hypothesized that the combination of SUMO E1 and TIGIT inhibition would synergistically induce anti-tumor immune effects. We used a clinically relevant orthotopic mouse model that consistently develops liver metastases to study this combination therapy alone and in the perioperative setting with surgical resection. The combination of SUMO E1 and TIGIT inhibition significantly prolonged survival. Complete responders exhibited protective immunity and enhanced T cell reactivity to model-specific alloantigens. Complementary immune analyses of resected tumors demonstrated that combination therapy more significantly reduces the abundance of regulatory FoxP3+CD4+ T cells than either monotherapy alone. Mechanistic studies suggest that SUMO E1 inhibition enhances antibody-mediated elimination of Tregs through innate immune cells, potentially by activation of type I interferon responses. Our results highlight a mechanism to enhance the efficacy of anti-TIGIT therapy.

In chordoma, epidermal growth factor receptor (EGFR) blockade shows significant but incomplete anti-tumor activity, suggesting that inhibition of other tumor growth promoting pathways is required for enhanced efficacy. Here, we detected high expression of cyclin-dependent kinase (CDK) 7 and 9 in both sacral and clival chordomas, and subsequently explored the efficacy of the CDKs inhibitors THZ1 and TG02, both as single agents and in combination with EGFR inhibitor afatinib in preclinical chordoma models. Monotherapy with THZ1, TG02, and afatinib led to decreased cell viability, proliferative capacity, colony formation and induced cell apoptosis across multiple chordoma cell lines, and enhanced activity was observed with THZ1/afatinib and TG02/afatinib co-treatments. Mechanistically, THZ1 and TG02 attenuated phosphorylation of POL II, leading to transcriptional inhibition of the chordoma driver gene brachyury, which was enhanced when combined with afatinib. Both CDK inhibitors also reduced expression of MCL1 which was further suppressed with combination therapy. Importantly, co-treatments exhibited greater inhibition of tumor growth than single treatments in cell line- and patient-derived xenograft models. Taken together, our data revealed that THZ1 or TG02 enhanced in vitro and in vivo efficacy of afatinib, suggesting a potential novel combination therapeutic strategy for patients with chordoma.