Cetuximab enhances the efficiency of irinotecan through simultaneously inhibiting the MAPK signaling and ABCG2 in colorectal cancer cells

Histopathological tumour microenvironment score independently predicts outcome in primary operable colorectal cancer

Colorectal cancer (CRC) is a heterogenous malignancy and research is focused on identifying novel ways to subtype patients. In this study, a novel classification system, tumour microenvironment score (TMS), was devised based on Klintrup-Mäkinen grade (KMG), tumour stroma percentage (TSP), and tumour budding. TMS was performed using a haematoxylin and eosin (H&E)-stained section from retrospective CRC discovery and validation cohorts (n = 1,030, n = 787). TMS0 patients had high KMG, TMS1 were low for KMG, TSP, and budding, TMS2 were high for budding, or TSP and TMS3 were high for TSP and budding. Scores were assessed for association with survival and clinicopathological characteristics. Mutational landscaping and Templated Oligo-Sequencing (TempO-Seq) profiling were performed to establish differences in the underlying biology of TMS. TMS was independently prognostic in both cohorts (p < 0.001, p < 0.001), with TMS3 predictive of the shortest survival times. TMS3 was associated with adverse clinical features including sidedness, local and distant recurrence, higher T stage, higher N stage, and presence of margin involvement. Gene set enrichment analysis of TempO-Seq data showed higher expression of genes associated with hallmarks of cancer pathways including epithelial to mesenchymal transition (p < 0.001), IL2 STAT5 signalling (p = 0.007), and angiogenesis (p = 0.017) in TMS3. Additionally, enrichment of immunosuppressive immune signatures was associated with TMS3 classification. In conclusion, TMS represents a novel and clinically relevant method for subtyping CRC patients from a single H&E-stained tumour section.

Human Blood Serum Can Diminish EGFR-Targeted Inhibition of Squamous Carcinoma Cell Growth through Reactivation of MAPK and EGFR Pathways

Regardless of the presence or absence of specific diagnostic mutations, many cancer patients fail to respond to EGFR-targeted therapeutics, and a personalized approach is needed to identify putative (non)responders. We found previously that human peripheral blood and EGF can modulate the activities of EGFR-specific drugs on inhibiting clonogenity in model EGFR-positive A431 squamous carcinoma cells. Here, we report that human serum can dramatically abolish the cell growth rate inhibition by EGFR-specific drugs cetuximab and erlotinib. We show that this phenomenon is linked with derepression of drug-induced G1S cell cycle transition arrest. Furthermore, A431 cell growth inhibition by cetuximab, erlotinib, and EGF correlates with a decreased activity of ERK1/2 proteins. In turn, the EGF- and human serum-mediated rescue of drug-treated A431 cells restores ERK1/2 activity in functional tests. RNA sequencing revealed 1271 and 1566 differentially expressed genes (DEGs) in the presence of cetuximab and erlotinib, respectively. Erlotinib- and cetuximab-specific DEGs significantly overlapped. Interestingly, the expression of 100% and 75% of these DEGs restores to the no-drug level when EGF or a mixed human serum sample, respectively, is added along with cetuximab. In the case of erlotinib, EGF and human serum restore the expression of 39% and 83% of DEGs, respectively. We further assessed differential molecular pathway activation levels and propose that EGF/human serum-mediated A431 resistance to EGFR drugs can be largely explained by reactivation of the MAPK signaling cascade.

ABCG2 Gene and ABCG2 Protein Expression in Colorectal Cancer-In Silico and Wet Analysis

ABCG2 (ATP-binding cassette superfamily G member 2) is a cell membrane pump encoded by the ABCG2 gene. ABCG2 can protect cells against compounds initiating and/or intensifying neoplasia and is considered a marker of stem cells responsible for cancer growth, drug resistance and recurrence. Expression of the ABCG2 gene or its protein has been shown to be a negative prognostic factor in various malignancies. However, its prognostic significance in colorectal cancer remains unclear. Using publicly available data, ABCG2 was shown to be underexpressed in colon and rectum adenocarcinomas, with lower expression compared to both the adjacent nonmalignant lung tissues and non-tumour lung tissues of healthy individuals. This downregulation could result from the methylation level of some sites of the ABCG2 gene. This was connected with microsatellite instability, weight and age among patients with colon adenocarcinoma, and with tumour localization, population type and age of patients for rectum adenocarcinoma. No association was found between ABCG2 expression level and survival of colorectal cancer patients. In wet analysis of colorectal cancer samples, neither ABCG2 gene expression, analysed by RT-PCR, nor ABCG2 protein level, assessed by immunohistochemistry, was associated with any clinicopathological factors or overall survival. An ABCG2-centered protein-protein interaction network build by STRING showed proteins were found to be involved in leukotriene, organic anion and xenobiotic transport, endodermal cell fate specification, and histone methylation and ubiquitination. Hence, ABCG2 underexpression could be an indicator of the activity of certain signalling pathways or protein interactors essential for colorectal carcinogenesis.

EGFR-targeted hybrid lipid nanoparticles for chemo-photothermal therapy against colorectal cancer cells

Antibody-functionalized targeted nanocarriers have shown great-potential for minimizing the chemoresistance and systemic toxicity of cancer chemotherapies. The combination of chemotherapy and photothermal therapy has great potential in improving therapeutic effect. However, cetuximab-modified nanoparticles based lipids for chemo-phototherapy of EGFR overexpressing colorectal carcinoma (CRC) have seldom been investigated. Hence, this study aimed to fabricate cetuximab-conjugated and near infrared (NIR) light-responsive hybrid lipid-polymer nanoparticles (abbreviated as Cet-CINPs) for targeted delivery of irinotecan. Cet-CINPs were prepared with copolymer PLGA and various lipids DSPE-PEG, DSPE-PEG-Mal, lecithin as carriers. Cetuximab was conjugated on the surface of nanoparticles to achieve targeting anti-tumor efficacy. Cet-CINPs were characterized in terms of morphology (spherical), size (119 nm), charge (-27.2 mV), drug entrapment efficiency (43.27 %), and antibody conjugation efficiency (70.87 %). Cet-CINPs showed preferable photothermal response, pH/NIR-triggered drug release behavior, enhanced cellular uptake and ROS level compared with free ICG and CINPs. Meanwhile, in vitro cytotoxicity assay showed that Cet-CINPs with NIR irradiation had a higher cytotoxicity against Lovo cells than non-targeted or non-NIR activated nanoparticles. The IC₅₀ values of Cet-CINPs with NIR irradiation was 22.84 ± 1.11 μM for 24 h and 5.01 ± 1.06 μM for 48 h, respectively. These investigations demonstrate that Cet-CINPs with good tumor-targeting ability and enhanced antitumor activity, are a promising multifunctional nanoplatform for CRC therapy.

Identification of AKT1/β-catenin mutations conferring cetuximab and chemotherapeutic drug resistance in colorectal cancer treatment

In anticancer therapy, the effectiveness of therapeutics is limited by mutations causing drug resistance. KRAS mutations are the only determinant for cetuximab resistance in patients with colorectal cancer (CRC). However, cetuximab treatment has not been fully successful in the majority of patients with wild-type (WT) KRAS. Therefore, it is important to determine new predictive mutations in CRC treatment. In the present study, the association between AKT1/β-catenin (CTNNB1) mutations with the drug resistance to cetuximab and other chemotherapeutics used in the CRC treatment was investigated by using site-directed mutagenesis, transfection, western blotting and cell proliferation inhibition assay. Cetuximab resistance was higher in the presence of AKT1 E17K, E49K and L52R mutations, as well as CTNNB1 T41A, S45F and S33P mutations compared with that of respective WT proteins. AKT1/CTNNB1 mutations were also associated with oxaliplatin, irinotecan, SN-38 and 5-fluorouracil resistance. Furthermore, mutant cell viability in oxaliplatin treatment was more effectively inhibited compared with that of the other chemotherapeutic drugs. In conclusion, AKT1/CTNNB1 mutations may be used as an important predictive biomarker in CRC treatment.