Targeting EGFR in metastatic colorectal cancer beyond the limitations of KRAS status: alternative biomarkers and therapeutic strategies

Effect of Secretion Efficiency of Mutant KRAS Neoantigen by Lactococcus lactis on the Immune Response of a Mucosal Vaccine Delivery Vehicle Targeting Colorectal Cancer

Colorectal cancer (CRC) is often caused by mutations in the KRAS oncogene, making KRAS neoantigens a promising vaccine candidate for immunotherapy. Secreting KRAS antigens using live Generally Recognized as Safe (GRAS) vaccine delivery hosts such as Lactococcus lactis is deemed to be an effective strategy in inducing specific desired responses. Recently, through the engineering of a novel signal peptide SPK1 from Pediococcus pentosaceus, an optimized secretion system was developed in the L. lactis NZ9000 host. In this study, the potential of the L. lactis NZ9000 as a vaccine delivery host for the production of two KRAS oncopeptides (mutant 68V-DT and wild-type KRAS) through the use of the signal peptide SPK1 and its mutated derivative (SPKM19) was investigated. The expression and secretion efficiency analyses of KRAS peptides from L. lactis were performed in vitro and in vivo in BALB/c mice. Contradictory to our previous study using the reporter staphylococcal nuclease (NUC), the yield of secreted KRAS antigens mediated by the target mutant signal peptide SPKM19 was significantly lower (by ~1.3-folds) compared to the wild-type SPK1. Consistently, a superior elevation of IgA response against KRAS aided by SPK1 rather than mutant SPKM19 was observed. Despite the lower specific IgA response for SPKM19, a positive IgA immune response from mice intestinal washes was successfully triggered following immunization. Size and secondary conformation of the mature proteins are suggested to be the contributing factors for these discrepancies. This study proves the potential of L. lactis NZ9000 as a host for oral vaccine delivery due to its ability to evoke the desired mucosal immune response in the gastrointestinal tract of mice.

CAR T-cells for colorectal cancer immunotherapy: Ready to go?

Chimeric antigen receptor (CAR) T-cells represent a new genetically engineered cell-based immunotherapy tool against cancer. The use of CAR T-cells has revolutionized the therapeutic approach for hematological malignancies. Unfortunately, there is a long way to go before this treatment can be developed for solid tumors, including colorectal cancer. CAR T-cell therapy for colorectal cancer is still in its early stages, and clinical data are scarce. Major limitations of this therapy include high toxicity, relapses, and an impermeable tumor microenvironment for CAR T-cell therapy in colorectal cancer. In this review, we summarize current knowledge, highlight challenges, and discuss perspectives regarding CAR T-cell therapy in colorectal cancer.

Deciphering the Role and Signaling Pathways of PKCα in Luminal A Breast Cancer Cells

Protein kinase C (PKC) comprises a family of highly related serine/threonine protein kinases involved in multiple signaling pathways, which control cell proliferation, survival, and differentiation. The role of PKCα in cancer has been studied for many years. However, it has been impossible to establish whether PKCα acts as an oncogene or a tumor suppressor. Here, we analyzed the importance of PKCα in cellular processes such as proliferation, migration, or apoptosis by inhibiting its gene expression in a luminal A breast cancer cell line (MCF-7). Differential expression analysis and phospho-kinase arrays of PKCα-KD vs. PKCα-WT MCF-7 cells identified an essential set of proteins and oncogenic kinases of the JAK/STAT and PI3K/AKT pathways that were down-regulated, whereas IGF1R, ERK1/2, and p53 were up-regulated. In addition, unexpected genes related to the interferon pathway appeared down-regulated, while PLC, ERBB4, or PDGFA displayed up-regulated. The integration of this information clearly showed us the usefulness of inhibiting a multifunctional kinase-like PKCα in the first step to control the tumor phenotype. Then allowing us to design a possible selection of specific inhibitors for the unexpected up-regulated pathways to further provide a second step of treatment to inhibit the proliferation and migration of MCF-7 cells. The results of this study suggest that PKCα plays an oncogenic role in this type of breast cancer model. In addition, it reveals the signaling mode of PKCα at both gene expression and kinase activation. In this way, a wide range of proteins can implement a new strategy to fine-tune the control of crucial functions in these cells and pave the way for designing targeted cancer therapies.

Efficacy and Safety of rCCK96-104PE38 Targeted Drug in the General Surgical Treatment of Colon Cancer

To evaluate the clinical efficacy and safety of the rCCK96-104PE38 targeted drug in patients with colon cancer in general surgery, data of 80 patients with colon cancer who were admitted to the hospital from April 2019 to July 2021 were selected and randomly divided into the treatment group and the control group, with 40 cases in each group. Patients in the treatment group were treated with the rCCK96-104PE38 targeted drug, and those in the control group were treated with oxaliplatin. The treatment efficiency and incidence of adverse reactions were compared between the two groups. The inverse cholecystokinin (CCK96-104) was fused with pseudomonas aeruginosa exotoxin (PE38 toxin) through the gene amplification technique to construct a prokaryotic expression vector. Then, the rCCK96-104PE38 was purified by Ni-nitrilotriacetate (Ni-NTA) affinity chromatography, and the antitumor activity of rCCK96-104PE38 was verified. The results showed that the amplified rCCK96-104PE38 sequence was correct and the pET-28a prokaryotic expression system was adopted to successfully achieve active expression. The purified recombinant protein could induce the apoptosis of colon cancer cells in vitro and inhibit tumor growth in vivo. The total effective rate in the treatment group (80%, 32/40) was higher than that in the control group (60%, 24/40) (P < 0.05). To sum up, the recombinant toxin rCCK96-104PE38 could not only specifically adsorb the colon cancer cells with high expression of CCK2R but also effectively inhibit tumor tissue growth and proliferation. Besides, the rCCK96-104PE38 protein had a good anticancer effect that helped effectively reduce the incidence of adverse reactions in patients, which was worthy of promoting.

Impact of fixation artifacts and threshold selection on high resolution melting analysis for KRAS mutation screening

INTRODUCTION

Treatment in metastatic colorectal cancer (mCRC) has expanded with monoclonal antibodies targeting epidermal growth factor receptor, but is restricted to patients with a wild-type (WT) KRAS mutational status. The most sensitive assays for KRAS mutation detection in formalin-fixed paraffin embedded (FFPE) tissues are based on real-time PCR. Among them, high resolution melting analysis (HRMA), is a simple, fast, highly sensitive, specific and cost-effective method, proposed as adjunct for KRAS mutation detection. However the method to categorize WT vs mutant sequences in HRMA is not clearly specified in available studies, besides the impact of FFPE artifacts on HRMA performance hasn't been addressed either.

METHODS

Avowedly adequate samples from 104 consecutive mCRC patients were tested for KRAS mutations by Therascreen™ (FDA Validated test), HRMA, and HRMA with UDG pre-treatment to reverse FFPE fixation artifacts. Comparisons of KRAS status allocation among the three methods were done. Focusing on HRMA as screening test, ROC curve analyses were performed for HRMA and HMRA-UDG against Therascreen™, in order to evaluate their discriminative power and to determine the threshold of profile concordance between WT control and sample for KRAS status determination.

RESULTS

Comparing HRMA and HRMA-UDG against Therascreen™ as surrogate gold standard, sensitivity was 1 for both HRMA and HRMA-UDG; and specificity and positive predictive values were respectively 0.838 and 0.939; and 0.777 and 0.913. As evaluated by the McNemar test, HRMA-UDG allocated samples to a WT/mutated genotype in a significatively different way from HRMA (p > 0.001). On the other hand HRMA-UDG did not differ from Therascreen™ (p = 0.125). ROC-curve analysis showed a significant discriminative power for both HRMA and HRMA-UDG against Therascreen™ (respectively, AUC of 0.978, p > 0.0001, CI 95% 0.957-0.999; and AUC of 0.98, p > 0.0001, CI 95% 0.000-1.0). For HRMA as a screening tool, the best threshold (degree of concordance between sample curves and WT control) was attained at 92.14% for HRMA (specificity of 0.887), and at 92.55% for HRMA-UDG (specificity of 0.952).

CONCLUSIONS

HRMA is a highly sensitive method for KRAS mutation detection, with apparently adequate and statistically significant discriminative power. FFPE sample fixation artifacts have an impact on HRMA results, so for HRMA on FFPE samples pre-treatment with UDG should be strongly suggested. The choice of the threshold for melting curve concordance has also great impact on HRMA performance. A threshold of 93% or greater might be adequate if using HRMA as a screening tool. Further validation of this threshold is required.

High expression of EGFR predicts poor survival in patients with resected T3 stage gastric adenocarcinoma and promotes cancer cell survival

Epidermal growth factor receptor (EGFR) is an essential regulator and biomarker of several types of cancer. However, the association between its expression and prognosis in patients with resected T3 stage gastric adenocarcinoma (RT3-GA) remains to be determined. In total, 683 patients with resectable T3-GA who underwent surgery were retrospectively included in the present study, and their immunohistochemical data for EGFR expression were collected. The associations between the patients' clinicopathologic characteristics and EGFR immunohistochemistry data were analyzed by multiple statistical methods. Annexin V apoptosis and MTT cell viability assays were performed to explore the effect of EGFR on AGS gastric adenocarcinoma cell survival. EGFR expression levels were categorized into two groups: low (406 cases) and high (277 cases). High EGFR was demonstrated to be significantly associated with distant metastasis (P=0.043) and severely decreased median overall survival time (MOST) and recurrence-free survival time (MRFST). MOST and MRFST in the low EGFR group were 39 and 37 months, respectively; whereas in the high EGFR group these values were only 18 and 13 months (P=3.10×10^-9 and P=6.74×10^-8, respectively). Multivariate analysis confirmed that high EGFR expression levels were associated with poor survival, which was associated with significantly increased recurrence risk and ~2-fold elevation in mortality risk [hazard ratio (HR), 1.73; 95% confidence interval (CI), 1.43-2.10; P=2.37×10^-8 and HR, 1.80; 95% CI, 1.50-2.17; P=3.80×10^-10]. Inhibiting EGFR with AG1478 suppressed its effect on promoting AGS cell survival. These results suggest that high EGFR expression indicates poor survival in patients with RT3-GA, which may be correlated with EGFR promoting GA cell survival.

Targeting non-canonical autophagy overcomes erlotinib resistance in tongue cancer

Acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) frequently occurs in many human cancers and hampers their therapeutic use. A large body of evidence has demonstrated the pro-survival role of autophagy in many human cancers. However, whether autophagy is involved in the induction of erlotinib resistance in tongue squamous cell carcinoma (TSCC) remains unknown. In this report, we found that autophagy prior to or induced by erlotinib treatment plays an important role in erlotinib resistance in tongue cancer cells. Using LC3 transfection, we observed that autophagy is upregulated and further induced when treated with erlotinib. Moreover, we found that autophagy plays a cytoprotective role by MTT analysis of the cell viability in TSCCs when treated with rapamycin or hydroxychloroquine (HCQ) in combination with erlotinib. However, 3-methyladenine (3-MA) did not influence the autophagy. Then, through siRNA technology and WB, we found that erlotinib-induced autophagy is mediated by ATG5 but not Beclin1. Also, knockdown of ATG5 significantly decreased the erlotinib resistance and knockdown of Beclin1 did not affect the sensitivity to erlotinib in TSCCs. Taken together, this indicates the critical role of non-canonical autophagy in erlotinib resistance in TSCCs.

From Molecular Biology to Clinical Trials: Toward Personalized Colorectal Cancer Therapy

During the past years, molecular studies through high-throughput technologies have led to the confirmation of critical alterations in colorectal cancer (CRC) and the discovery of some new ones, including mutations, DNA methylations, and structural chromosomal changes. These genomic alterations might act in concert to dysregulate specific signaling pathways that normally exert their functions on critical cell phenotypes, including the regulation of cellular metabolism, proliferation, differentiation, and survival. Targeted therapy against key components of altered signaling pathways has allowed an improvement in CRC treatment. However, a significant percentage of patients with CRC and metastatic CRC will not benefit from these targeted therapies and will be restricted to systemic chemotherapy. Mechanisms of resistance have been associated with specific gene alterations. To fully understand the nature and significance of the genetic and epigenetic defects in CRC that might favor a tumor evading a given therapy, much work remains. Therefore, a dynamic link between basic molecular research and preclinical studies, which ultimately constitute the prelude to standardized therapies, is very important to provide better and more effective treatments against CRC. We present an updated revision of the main molecular features of CRC and their associated therapies currently under study in clinical trials. Moreover, we performed an unsupervised classification of CRC clinical trials with the aim of obtaining an overview of the future perspectives of preclinical studies.

Targeting ADAM-17 with an inhibitory monoclonal antibody has antitumour effects in triple-negative breast cancer cells

Background:

Identification and validation of a targeted therapy for triple-negative breast cancer (TNBC), that is, breast cancers negative for oestrogen receptors, progesterone receptors and HER2 amplification, is currently one of the most urgent problems in breast cancer treatment. EGFR is one of the best-validated driver genes for TNBC. EGFR is normally activated following the release of ligands such as TGFα, mediated by the two MMP-like proteases ADAM (a disintegrin and metalloproteinase)-10 and ADAM-17. The aim of this study was to investigate the antitumour effects of a monoclonal antibody against ADAM-17 on an in vitro model of TNBC.

Methods:

We investigated an inhibitory cross-domain humanised monoclonal antibody targeting both the catalytic domain and the cysteine-rich domain of ADAM17-D1(A12) in the HCC1937 and HCC1143 cell lines.

Results:

D1(A12) was found to significantly inhibit the release of TGFα, and to decrease downstream EGFR-dependent cell signalling. D1(A12) treatment reduced proliferation in two-dimensional clonogenic assays, as well as growth in three-dimensional culture. Furthermore, D1(A12) reduced invasion of HCC1937 cells and decreased migration of HCC1143 cells. Finally, D1(A12) enhanced cell death in HCC1143 cells.

Conclusion:

Our in vitro findings suggest that targeting ADAM-17 with D1(A12) may have anticancer activity in TNBC cells.