Cetuximab resistance induced by hepatocyte growth factor is overcome by MET inhibition in KRAS, NRAS, and BRAF wild-type colorectal cancers

Inhibition of autocrine HGF maturation overcomes cetuximab resistance in colorectal cancer

Although amplifications and mutations in receptor tyrosine kinases (RTKs) act as bona fide oncogenes, in most cancers, RTKs maintain moderate expression and remain wild-type. Consequently, cognate ligands control many facets of tumorigenesis, including resistance to anti-RTK therapies. Herein, we show that the ligands for the RTKs MET and RON, HGF and HGFL, respectively, are synthesized as inactive precursors that are activated by cellular proteases. Our newly generated HGF/HGFL protease inhibitors could overcome both de novo and acquired cetuximab resistance in colorectal cancer (CRC). Conversely, HGF overexpression was necessary and sufficient to induce cetuximab resistance and loss of polarity. Moreover, HGF-induced cetuximab resistance could be overcome by the downstream MET inhibitor, crizotinib, and upstream protease inhibitors. Additionally, HAI-1, an endogenous inhibitor of HGF proteases, (i) was downregulated in CRC, (ii) exhibited increased genomic methylation that correlated with poor prognosis, (iii) HAI-1 expression correlated with cetuximab response in a panel of cancer cell lines, and (iv) exogenous addition of recombinant HAI-1 overcame cetuximab resistance in CC-HGF cells. Thus, we describe a targetable, autocrine HAI-1/Protease/HGF/MET axis in cetuximab resistance in CRC.

Deciphering treatment resistance in metastatic colorectal cancer: roles of drug transports, EGFR mutations, and HGF/c-MET signaling

In 2023, colorectal cancer (CRC) is the third most diagnosed malignancy and the third leading cause of cancer death worldwide. At the time of the initial visit, 20% of patients diagnosed with CRC have metastatic CRC (mCRC), and another 25% who present with localized disease will later develop metastases. Despite the improvement in response rates with various modulation strategies such as chemotherapy combined with targeted therapy, radiotherapy, and immunotherapy, the prognosis of mCRC is poor, with a 5-year survival rate of 14%, and the primary reason for treatment failure is believed to be the development of resistance to therapies. Herein, we provide an overview of the main mechanisms of resistance in mCRC and specifically highlight the role of drug transports, EGFR, and HGF/c-MET signaling pathway in mediating mCRC resistance, as well as discuss recent therapeutic approaches to reverse resistance caused by drug transports and resistance to anti-EGFR blockade caused by mutations in EGFR and alteration in HGF/c-MET signaling pathway.

Exosomes derived from MDR cells induce cetuximab resistance in CRC via PI3K/AKT signaling‑mediated Sox2 and PD‑L1 expression

The anti-EGFR antibody cetuximab is used as a first-line targeted therapeutic drug in colorectal cancer. It has previously been reported that the efficacy of the EGFR antibody cetuximab is limited by the emergence of acquired drug resistance. In our previous study the transmissibility effect of exosomes from drug resistant tumor cells to sensitive tumor cells was identified. It can therefore be hypothesized that drug resistant cells might affect neighboring and distant cells via regulation of exosome composition and behavior. However, the mechanism of exosomes in KRAS-wild-type colorectal cancer (CRC) remains unknown. In the present study, functional analysis of overall survival post-diagnosis in patients with KRAS wild-type and those with mutant CRC was performed using human CRC specimens. Furthermore, it was demonstrated that multidrug resistance (MDR) cancer cell-derived exosomes were potentially a key factor, which promoted cetuximab-resistance in CRC cells and reduced the inhibitory effect of cetuximab in CRC xenograft models. The Cell Counting Kit-8 and colony formation assays were performed to assess the effects of exosomes derived from CRC/MDR cells on cetuximab resistance. Sphere formation assay results demonstrated that exosomes derived from CRC/MDR cells altered the self-renewal and multipotential ability of stem-cell-associated markers and facilitated resistance to cetuximab in cetuximab-sensitive cells. Furthermore, exosomes derived from CRC/MDR cells decreased sensitivity to cetuximab via the activation of PI3K/AKT signaling, which promoted Sox2 and programmed death-ligand 1 (PD-L1) mRNA and protein expression according to reverse transcription-quantitative PCR, western blotting and immunohistochemistry analyses, as well as apoptosis resistance both in vitro and in vivo according to a TUNEL assay. In conclusion, the results of the present study demonstrated that exosomes derived from CRC/MDR cells may promote cetuximab resistance in KRAS wild-type cells via activation of the PI3K/AKT signaling pathway-mediated expression of Sox2 and PD-L1, which will be useful for investigating a potential clinical target in predicting cetuximab resistance.

ACY1 Downregulation Enhances the Radiosensitivity of Cetuximab-Resistant Colorectal Cancer by Inactivating the Wnt/β-Catenin Signaling Pathway

Treatment of cetuximab-resistant colorectal cancer (CRC) is a global healthcare problem. This study aimed to assess the effects of radiotherapy on cetuximab-resistant CRC and explore the underlying mechanism. We established a cetuximab-resistant HCT116 cell line (HCT116-R) by extracorporeal shock. Differentially expressed mRNAs were screened from cells treated with different radiation doses using second-generation high-throughput sequencing. Sequence data showed that ACY1 was significantly downregulated in HCT116-R cells after irradiation. Analysis of the GEO and TCGA datasets revealed that high ACY1 expression was associated with lymph node metastasis and a poor prognosis in CRC patients. In addition, immunohistochemistry results from CRC patients revealed that ACY1 protein expression was related to cetuximab resistance and lymph node metastasis. These findings suggested that ACY1 may function as an oncogene to promote CRC progression and regulate the radiosensitivity of cetuximab-resistant CRC. As expected, ACY1 silencing weakened the proliferation, migration, and invasion abilities of HCT116-R cells after radiotherapy. Mechanistically, TCGA data demonstrated that ACY1 expression was closely related to the Wnt/β-catenin pathway in CRC. We validated that radiotherapy first reduced β-catenin levels, followed by decreased expression of the metastasis-related protein E-cadherin. Silencing ACY1 dramatically enhanced these changes in β-catenin and E-cadherin after radiotherapy. In conclusion, ACY1 downregulation could enhance the radiosensitivity of cetuximab-resistant CRC by inactivating Wnt/β-catenin signaling, implying that ACY1 may serve as a radiotherapy target for cetuximab-resistant CRC.

The Expression Quantitative Trait Loci in Immune Response Genes Impact the Characteristics and Survival of Colorectal Cancer

The impact of germline variants on the regulation of the expression of tumor microenvironment (TME)-based immune response genes remains unclear. Expression quantitative trait loci (eQTL) provide insight into the effect of downstream target genes (eGenes) regulated by germline-associated variants (eVariants). Through eQTL analyses, we illustrated the relationships between germline eVariants, TME-based immune response eGenes, and clinical outcomes. In this study, both RNA sequencing data from primary tumor and germline whole-genome sequencing data were collected from patients with stage III colorectal cancer (CRC). Ninety-nine high-risk subjects were subjected to immune response gene expression analyses. Seventy-seven subjects remained for further analysis after quality control, of which twenty-two patients (28.5%) experienced tumor recurrence. We found that 65 eQTL, including 60 germline eVariants and 22 TME-based eGenes, impacted the survival of cancer patients. For the recurrence prediction model, 41 differentially expressed genes (DEGs) achieved the best area under the receiver operating characteristic curve of 0.93. In total, 19 survival-associated eGenes were identified among the DEGs. Most of these genes were related to the regulation of lymphocytes and cytokines. A high expression of HGF, CCR5, IL18, FCER1G, TDO2, IFITM2, and LAPTM5 was significantly associated with a poor prognosis. In addition, the FCER1G eGene was associated with tumor invasion, tumor nodal stage, and tumor site. The eVariants that regulate the TME-based expression of FCER1G, including rs2118867 and rs12124509, were determined to influence survival and chromatin binding preferences. We also demonstrated that FCER1G and co-expressed genes in TME were related to the aggregation of leukocytes via pathway analysis. By analyzing the eQTL from the cancer genome using germline variants and TME-based RNA sequencing, we identified the eQTL in immune response genes that impact colorectal cancer characteristics and survival.