Carcinogenesis最新文献

Pancreatic ductal adenocarcinoma (PDA) is a lethal disease for which remarkable therapeutic resistance is the norm. Conventional immunotherapies, like immune checkpoint inhibitors, show limited efficacy in PDA due to a remarkably immunosuppressive tumor microenvironment (TME) and systemic inflammation. This review discusses the potential of both exogenous and in situ vaccination strategies to overcome these barriers and enhance anti-tumor immunity in PDA. Exogenous vaccines, including whole-cell, dendritic cell, peptide, and nucleic acid-based vaccines, have shown varying degrees of promise but face challenges related to antigen selection, production complexities, and patient-specific factors. In contrast, in situ vaccination strategies leverage conventional cytotoxic therapies, such as chemotherapy and radiation therapy, to induce immunogenic cell death and modulate the TME with the aim to stimulate anti-tumor immunity. While preclinical studies support the use of in situ vaccination, balancing the stimulatory and inhibitory effects is likely fundamental to eliciting productive anti-tumor responses in patients. Ongoing research seeks to identify new innovative strategies that can harness the endogenous immune response and trigger in situ vaccination. Overall, while both vaccination approaches offer significant potential, further research and clinical trials will be needed to optimize these strategies for improving patient outcomes in PDA.

Precision oncology and tumor-agnostic drug development provide hope for enhancing outcomes among patients with pancreatic cancer. Tumor-agnostic therapies have emerged across various tumor types, driven by insights into shared biomarkers. In the case of pancreatic cancer, the prevalence of the KRAS gene mutation is noteworthy. However, there exist other actionable alterations, such as BRCA1/2 mutations and fusion genes (BRAF, FGFR2, RET, NTRK, NRG1, and ALK), which present potential targets for therapy. Notably, tumor-agnostic drugs have demonstrated efficacy in specific subsets of pancreatic cancer patients who harbor these genetic alterations. Despite the rarity of NTRK fusions in pancreatic cancer, larotrectinib and entrectinib have exhibited effectiveness in NTRK fusion-positive pancreatic cancers. Additionally, repotrectinib, a next-generation NTRK inhibitor, has shown promising activity in NTRK positive pancreatic cancer patients who have developed acquired resistance to previous NTRK inhibitors. Immune checkpoint inhibitors, such as pembrolizumab and dostarlimab, have proven to be effective in dMMR/MSI-H pancreatic cancers. Moreover, targeted therapies for BRAF V600, RET fusions, and HER2/neu overexpression have displayed promising results in specific subsets of pancreatic cancer patients. Emerging targets like NRG fusions, FGFR2 fusions, TP53 mutations, and KRAS G12C mutations present potential avenues for targeted therapy. Tumor-agnostic therapies have the potential to revolutionize pancreatic cancer treatment by focusing on specific genetic alterations. It is crucial to continue implementing comprehensive screening strategies that encompass the ability to detect all these tumor-agnostic biomarkers. This will be essential in identifying pancreatic cancer patients who may benefit from these therapies.

We investigated the interplay among oxidative DNA damage and repair, expression of genes encoding major base excision repair (BER) enzymes and bypass DNA polymerases, and mutagenesis in mammalian cells. Primary mouse embryonic fibroblasts were challenged with oxidative stress induced by methylene blue plus visible light, and formation and repair of DNA damage, changes in gene expression, and mutagenesis were determined at increasing intervals posttreatment (0-192 hours). Significant formation of oxidative DNA damage together with upregulation of Ogg1, Polβ, and Polκ, and no changes in Mutyh and Nudt1 expression were found in treated cells. There was a distinct interconnection between Ogg1 and Polβ expression and DNA damage formation and repair whereby changes in expression of these two genes were proportionate to the levels of oxidative DNA damage, once a 3-plus hour lag time passed (P < .05). Equally notable was the matching pattern of Polκ expression and kinetics of oxidative DNA damage and repair (P < .05). The DNA damage and gene expression data were remarkably consistent with mutagenicity data in the treated cells; the induced mutation spectrum is indicative of erroneous bypass of oxidized DNA bases and incorporation of oxidized deoxynucleoside triphosphates during replication of the genomic DNA. Our findings support follow-up functional studies to elucidate how oxidation of DNA bases and the nucleotide pool, overexpression of Polκ, delayed upregulation of Ogg1 and Polβ, and inadequate expression of Nudt1 and Mutyh collectively affect mutagenesis consequent to oxidative stress.

Pancreatic ductal adenocarcinoma (PDAC) manifests diverse molecular subtypes, including the classical/progenitor and basal-like/squamous subtypes, with the latter known for its aggressiveness. We employed integrative transcriptome and metabolome analyses to identify potential genes contributing to the molecular subtype differentiation and its metabolic features. Our comprehensive analysis revealed that adrenoceptor alpha 2A (ADRA2A) was downregulated in the basal-like/squamous subtype, suggesting its potential role as a candidate suppressor of this subtype. Reduced ADRA2A expression was significantly associated with a high frequency of lymph node metastasis, higher pathological grade, advanced disease stage, and decreased survival among PDAC patients. In vitro experiments demonstrated that ADRA2A transgene expression and ADRA2A agonist inhibited PDAC cell invasion. Additionally, ADRA2A-high condition downregulated the basal-like/squamous gene expression signature, while upregulating the classical/progenitor gene expression signature in our PDAC patient cohort and PDAC cell lines. Metabolome analysis conducted on the PDAC cohort and cell lines revealed that elevated ADRA2A levels were associated with suppressed amino acid and carnitine/acylcarnitine metabolism, which are characteristic metabolic profiles of the classical/progenitor subtype. Collectively, our findings suggest that heightened ADRA2A expression induces transcriptome and metabolome characteristics indicative of classical/progenitor subtype with decreased disease aggressiveness in PDAC patients. These observations introduce ADRA2A as a candidate for diagnostic and therapeutic targeting in PDAC.

Multiple primary lung tumor is garnering attention from clinicians, with adenocarcinoma emerging as the predominant histological type. Because of the heterogeneity and diffuse distribution of lesions in the same patient, the treatment of multiple primary lung adenocarcinoma (MPLA) is a significant challenge. As a kind of variation unaffected by tumor heterogeneity, germline alterations may play a key role in the development of MPLA. Here, whole-exome sequencing (WES) of peripheral blood was employed to obtain germline alteration data. Intergroup comparative analyses on rare and deleterious alterations of MPLA, solitary lung adenocarcinoma, and healthy individuals in a MPLA family were performed to clarify the candidate alterations. WES and targeted Sanger sequencing were performed in 27 disseminated MPLA patients to detect the mutation site that had been screened. A rare and deleterious germline alteration, EPHB4R91H, was found in all of the patients of an MPLA family and a patient with disseminated MPLA. It was revealed that EPHB4R91H was able to enhance the proliferation, migration, and invasion ability of A549 cells through increased binding affinity to ephrinB2, which in turn activated the EPHB4/ERK/JNK/MAPK pathway. Our findings corroborate that germline alterations are involved in the development of MPLA. And it was found for the first time that the EPHB4R91H mutation promotes the development of MPLA by enhancing its affinity for ephrinB2 and thereby active EPHB4/ERK/JNK/MAPK pathway.

A noticeable characteristic of pancreatic ductal adenocarcinoma (PDAC) tumors is a dense tumor microenvironment with abundant and dense, desmoplastic stroma woven tightly with both cellular and matrix components. The high stromal density is associated with higher intratumor pressures which, until the last decade, was largely assumed to be tumor protective, confirmed by early studies demonstrating that altering the stroma was effective in genetically engineered models of PDAC. However, clinical trials using these approaches have been disappointing. There is increasing recognition that stroma heterogeneity is much greater than initially thought with an explosion of investigation into cancer-associated fibroblast (CAF) subpopulations led by experimental and single-cell transcriptomic studies. This review summarizes and attempts to harmonize the current transcriptomic data of CAF subpopulations. Understanding the heterogeneity of CAFs, the matrix, and other tumor microenvironment features will be critical to developing effective therapeutic approaches. Identifying model systems that best recapitulate the clinical behavior and treatment response of human PDAC will be important. Examining subpopulations as defined by clinical outcome will remain a critical step in defining clinically impactful CAF subtypes in larger clinical cohorts. The future of precision oncology in PDAC will depend on the integration of precision tumor epithelial and precision stroma approaches.

BRAF V600E, one of the most frequent mutations in the MAPK pathway, confers poor prognosis to colorectal cancers (CRCs), partly because of chemotherapeutic resistance. Oncogene-induced DNA damage responses (DDRs) that primarily activate p53 are important mechanistic barriers to the malignant transformation of cells; however, the mechanism underlying this impairment in cancer remains unknown. Here, we evaluated the responses of BRAFV600E-induced DDRs in two CRC cell lines, SW48 and LIM1215, both of which harbor wild-type TP53, KRAS, and BRAF. BRAFV600E transduction exhibited distinct phenotypes in these cells: SW48 cell proliferation markedly decreased, whereas that of LIM1215 increased. BRAFV600E expression induced the activation of oncogene-induced DDR signaling in SW48 cells, but not in LIM1215 cells, whereas chemotherapeutic agents similarly activated DDRs in both cell lines. Knockdown experiments revealed that these responses in SW48 cells were mediated by p53-p21 pathway activation. Comet assay (both alkaline and neutral) revealed that BRAFV600E increased single-strand breaks to the same extent in both cell lines; however, in the case of LIM1215 cells, it only facilitated double-strand breaks. Furthermore, the proliferation of LIM1215 cells, wherein no oncogene-induced DDRs occurred, was synergistically inhibited upon MDM2 inhibitor-mediated p53 activation combined with MEK inhibition. Taken together, these distinct DDR signaling responses highlight the novel characteristics of BRAFV600E-mutated CRC cells and define the therapeutic potential of p53 activation combined with MAPK inhibition against TP53 wild-type CRC harboring a BRAFV600E mutation.