Molecular Oncology最新文献

Rearranged during transfection (RET) fusions drive subsets of non-small cell lung cancer (NSCLC) and papillary thyroid carcinoma (PTC). Despite new selective RET tyrosine kinase inhibitors (TKIs), resistance usually occurs and is often driven by RET-independent bypass mechanisms. Previous studies have implied crosstalk between RET and proto-oncogene tyrosine-protein kinase SRC, but the anticancer effects of targeting SRC combined with selective RET TKIs, and the underlying molecular mechanisms involved, are not fully understood. Our results show that the multitargeted SRC TKI dasatinib significantly enhanced the efficacy of RET TKIs in RET fusion-positive (RET⁺) NSCLC and PTC cells. Genetic rescue experiments validated that the combination effects between RET TKIs and dasatinib were indeed SRC-dependent. Phosphoproteomics analysis and validation using selective inhibitors and small interfering RNAs (siRNAs) determined that synergy was primarily mediated by suppression of downstream serine/threonine-protein kinase PAK signaling, with contributions from AKT and ribosomal protein S6. Importantly, synergy was also observed with eCF506 (NXP900), a next-generation clinical SRC inhibitor. Finally, both SRC TKIs restored sensitivity in selpercatinib-resistant RET⁺ PTC cells. These results elucidate RET and SRC signaling crosstalk in RET⁺ NSCLC and PTC, suggesting that co-inhibiting SRC has clinical potential in TKI-naïve and -resistant RET⁺ cancers.

Metastatic colorectal cancer (mCRC), particularly microsatellite stable (MSS) cases, often exhibits limited responsiveness to immunotherapy, leaving chemotherapy as the primary treatment option. While chemotherapy effectively targets tumor cells, its impact on the broader mutational landscape, including passenger mutations in large genes such as Titin (TTN), remains poorly understood. Passenger mutations, traditionally deemed biologically inert, may reflect tumor mutational burden (TMB) and influence treatment outcomes. In our study involving whole exome sequencing of paired primary and metastatic tumor samples from 22 mCRC patients, recurrent driver mutations in APC, KRAS, and TP53 were consistently observed. However, passenger mutations in large genes, particularly TTN, were notably enriched in chemonaïve specimens and associated with higher TMB. Chemotherapy-treated samples exhibited a significant reduction in these mutations, suggesting selective depletion of hypermutated subclones. Our findings demonstrate that chemotherapy may selectively reduce passenger mutations in mCRC, potentially influencing the persistence of hypermutated subclones. This highlights the potential role of passenger mutation patterns and TMB as biomarkers for treatment response and raises the hypothesis that they could help guide immunotherapy considerations for patients with MSS mCRC.

Cancer stem cells (CSCs) drive tumor initiation, metastasis, and therapy resistance. The role of cytoplasmic cyclin-dependent kinase inhibitor 1A (CDKN1A, p21) in CSC biology remains unclear. Since cytoplasmic p21 correlated with advanced stage and metastasis in colorectal cancer (CRC) patients, we investigated its causal role in CSC features in vitro and in vivo. Cytoplasmic p21 increased spheroid formation and CD133 expression in a mechanism partly dependent on AKT activation. Phosphomimetic p21 (p21^T145D) enhanced spheroid growth, CD133, and stemness factors (Oct3/4, Nanog, Sox2), whereas nuclear p21 (p21^T145A) reduced them. Immunoprecipitation, proximity ligation assays, and in silico modeling demonstrated that cytoplasmic p21 interacts with the NFκB-IκB complex, promoting NFκB release and activation. Consequently, NFκB targets BCL-xL and COX2 were upregulated in p21^T145D- and AKT^T308D,S473D CRC cells in vitro and in a chorioallantoic membrane (CAM) model, supporting their role as downstream effectors of cytoplasmic p21. Our findings uncover a new function of cytoplasmic p21 in regulating CSC properties through NFκB modulation. Screening p21 subcellular localization may stratify CRC patients with high metastatic risk providing a basis for CSC-targeted therapeutic strategies.

Despite the promising results of non-thermal plasma (NTP) devices for cancer therapy, the potential adverse effects of NTP irradiation have remained unexplored, including the effects on epithelial-mesenchymal transition (EMT) and subsequent cancer metastasis. In this study, we investigate NTP-induced EMT initiation and progression. A microsecond-pulsed dielectric barrier discharge plasma device was used for NTP treatment, and chicken chorioallantoic membrane (CAM) and spheroids were used as 3D tumor models. NTP treatment reduced tumor volume in the CAM model, but a shift towards a mesenchymal-like phenotype was also measured in melanoma tumors via analysis of the six EMT biomarkers, though changes in cancer cell migration to other organs were not significant. In the spheroid model, molecular analysis also indicated an EMT response following NTP treatment, and enhanced cell migration was measured in one cell line. EMT induction with NTP was dose-dependent and transient; high NTP treatments caused significant EMT response and enhanced migration, but low NTP doses did not. Our findings highlight the important role of NTP parameters for cancer treatment and consequential EMT responses. The insights obtained here further build the foundation for clinical optimization, harnessing the cancer-killing potential of NTP while safeguarding against undesirable EMT-related outcomes.

Identifying innovative therapeutic strategies is crucial to improve clinical management of ovarian cancer. Previously, we showed that ovarian cancer cell apoptosis can be triggered by inhibiting the anti-apoptotic proteins Bcl-x_L and Mcl-1 and/or by inducing their pro-apoptotic partners Bim, Puma, and Noxa. The expression of these pro-apoptotic proteins can be hindered by excessive histone deacetylation, resulting from HDAC overexpression. This study aimed to evaluate whether belinostat, an FDA-approved pan-HDAC inhibitor, could increase Bim, Puma, and/or Noxa expression and induce ovarian cancer cell death, either alone or in combination with strategies targeting Bcl-x_L or Mcl-1. Belinostat exerted a cytostatic effect and, at higher concentrations, an apoptotic effect in SKOV3 and IGROV1-R10 ovarian cancer cells. It induced a concentration-dependent increase in Bim, Puma, and Noxa protein expression, while partially repressing that of Bcl-x_L. Inhibition of Bcl-x_L sensitized both cell lines to belinostat, as did inhibition of Mcl-1 in IGROV1-R10 cells. Interestingly, belinostat's anticancer activity was also enhanced by inhibitors of Bcl-x_L or Mcl-1 in patient-derived tumor organoids. This study therefore positions belinostat-based strategies as promising therapies for ovarian cancer.

Genetic alterations in key oncogenes have been frequently identified in lung adenocarcinoma (LUAD), including genes encoding epidermal growth factor receptor (EGFR), Kirsten rat sarcoma viral oncogene homolog (KRAS), and anaplastic lymphoma kinase (ALK). In this pilot study, we aimed to characterize the differences in enriched biological pathways and phosphorylation events between LUAD tumors harboring EGFR, KRAS, or echinoderm microtubule-associated protein-like 4 (EML4)-ALK oncogenic alterations and triple wild-type LUAD tumors (WT, without EML4-ALK, KRAS, or EGFR alterations) by mass spectrometry (MS)-based quantitative proteomics and phosphoproteomics. We analyzed tumor regions of 82 formalin-fixed paraffin-embedded (FFPE) tissue sections with 6, 23, 31, and 22 samples from the EML4-ALK, EGFR, KRAS, and WT sample groups, respectively. A total of 1377 to 2189 proteins and 73 to 1781 phosphosites were quantified in these analyses. Based on the results, the samples clustered according to their genetic alteration type, and EGFR-mutated samples showed unique protein expression patterns. Membrane organization, vesicle organization, and vesicle-mediated transport Gene Ontology Biological Process (GOBP) terms were significantly downregulated in EGFR-mutated samples compared to the other sample groups. Changes in 36 proteins and 52 phosphosites were also identified as potentially specific to a given genetic alteration. Many of these proteins have previously been linked to EGFR or KRAS mutations [e.g., cathepsin L, stimulator of interferon genes protein (STING)], whereas several phosphoproteins are associated with RNA splicing [e.g., serine/arginine-rich splicing factor 1 (SRSF1), SRSF2, and SRSF7 proteins]. Kinase-substrate enrichment analysis indicated altered activities of 10 kinases, including mitogen-activated protein kinases (MAPKs) and cyclin-dependent kinases (CDKs). For example, CDK2 activity was elevated in EML4-ALK samples compared to the other sample groups. Our results could provide significant insights into further studies that could contribute to developing improved diagnostic and therapeutic strategies for LUAD.

Leukemia stem cells (LSCs) are critical for leukemia initiation, and the stemness properties of LSCs are related to disease relapse. Stemness properties, including quiescence, self-renewal, and chemoresistance, are maintained through an interplay between leukemia cells and the bone marrow (BM) niche. Here, we demonstrated that DNA damage-inducible transcript 4 (DDIT4) can be induced in a hypoxic BM niche and is required for the quiescence and self-renewal of AML1-ETO9a (AE9a)-transformed leukemia cells in vitro. More importantly, analysis of publicly available transcriptional data from adult acute myeloid leukemia (AML) patients revealed that elevated DDIT4 expression correlates with poor prognosis. Furthermore, DDIT4 knockout markedly suppressed leukemia initiation, quiescence, chemoresistance, and self-renewal of AE9a-transformed leukemia cells in vivo. Mechanistically, DDIT4 upregulates the expression of HOXA gene cluster, and re-expression of HOXA6 in DDIT4 knockout AE9a cells can rescue the impaired leukemia initiation. Our findings demonstrate the critical role of DDIT4 in the stemness of AE9a leukemia cells and elucidate its underlying mechanism, suggesting that targeting DDIT4 may represent a promising therapeutic strategy for eliminating LSCs in AML1-ETO leukemia.

RAS oncoproteins have been considered undruggable for decades. However, recent advances have led to the development of a large variety of RAS inhibitors. While a multitude of drugs is currently under clinical evaluation, some of them have already been approved in specific contexts, leading to a continuous improvement of available therapeutic options for patients with RAS-mutant cancers. In this Viewpoint, we discuss different classes of RAS inhibitors, with emphasis on those that are currently tested in the clinic including allele-specific KRAS, panKRAS, and panRAS inhibitors. We also address determinants of response to RAS inhibition such as the tumor context or potential resistance mechanisms. Finally, we provide an outlook on the future of RAS targeting, which is likely to involve combination therapies. The rapid approval of several RAS inhibitors reflects the urgency to develop novel therapeutic strategies to treat RAS-mutant cancers.

Excised signal circles (ESC) are circular DNA molecules generated during T- and B-cell maturation. Previously considered biologically inert, recent work by Gao et al. now show that ESCs can replicate and accumulate in healthy lymphocytes. Moreover, the authors link higher levels of ESCs to an increased risk of relapse in B-cell leukemia patients and propose that this phenomenon is due to the unique ability of ESCs to induce genome instability.

Erb-b2 receptor tyrosine kinase 2 (ERBB2; also known as HER2) expression is observed in 25-40% of head and neck squamous cell carcinomas (HNSCC), yet there are no anti-HER2 therapies under evaluation for HNSCC, as conventional cytostatic anti-HER2 antibodies have had limited effectiveness and levels of HER2 overexpression are lower in HNSCC tumors compared to breast cancer. Trastuzumab-deruxtecan (T-DXd; Enhertu) is a HER2-targeting antibody-drug conjugate (ADC) comprising an anti-HER2 monoclonal antibody, a cleavable linker, and a potent topoisomerase I inhibitor payload, and has shown promising results in very low HER2-expressing tumors. We compare the efficacy of T-DXd, trastuzumab-emtansine (ADC comprising an anti-HER2 antibody and microtubule inhibitor, T-DM1; Kadcyla) and trastuzumab (Herceptin) therapy in HNSCC with low and absent HER2 expression in vitro and in vivo. In vitro treatment of a low HER2-expressing human HNSCC cell line (FaDu) with T-DXd resulted in dose-dependent cell death (IC50 values of 9856 ng·mL^-1). T-DXd treatment of FaDu and UMSCC-47 (low HER2-expressing cell line) mouse xenografts displayed antitumor activity (P = 0.0001 and 0.015 respectively). When comparing T-DXd to other approved anti-HER2 therapies, only FaDu mice treated with T-DXd showed a reduction in tumor growth (P = 0.0012). In UMSCC-1 cells (absent HER2 expression), the drug failed to accumulate in tumors and showed no measurable antitumor effect, in contrast to FaDu xenografts, where drug accumulation in the tumor correlated with a therapeutic response. T-DXd treatment yielded antitumor activity in FaDu and UMSCC-47 tumors, highlighting the potential for T-DXd efficacy in low HER2-expressing tumors.