Expression profile of NF-κB regulated genes in sporadic colorectal cancer patients

Gut commensal bacteria influence colorectal cancer development by modulating immune response in AOM/DSS-treated mice

The gut microbiota has been closely associated with the pathogenesis of colorectal cancer (CRC). However, precise identification of particular microorganisms promoting CRC carcinogenesis, and more importantly those blocking tumor development, has been challenging based on human gut microbiota profiling studies. With a well-established azoxymethane/dextran sodium sulfate induction murine CRC model, we found a subset of mice consistently failed to develop CRC. This genetically homogeneous but cancer-refractory population gave us a unique opportunity to reveal that the microbial compositions between mice with and without CRC formation are indeed distinct, indicating key different gut microbiota between those groups are responsible for the differential susceptibility of the animals to CRC development. Our analysis revealed that Ruminococcus flavefaciens (R.f) and Fibrobacter succinogenes (F.s) were significantly enriched in CRC-free mice, while the presence of Eubacterium dolichum (E.d) was dramatically reduced. The correlative evidence was further substantiated as important causal factors, with subsequent bacteria intragastric administration experiments demonstrating independent, protective roles of R.f and F.s and a correspondingly detrimental role of E.d in inflammation-induced CRC initiation. Notably, E.d strongly activates NF-κB and promotes the local accumulation of myeloid-derived suppressor cells and macrophages. Significant disturbance of gut immune homeostasis, therefore, might be a critical trigger leading to subsequent CRC development. These findings indicate a clear direction for precise and rational gut microbiota-mediated CRC prevention.IMPORTANCEThere is a complex ecosystem of different microbes residing within the gut, which is highly relevant to health and diseases. The causal linkage between specific gut microbes and the development of colorectal cancer has been established with a mouse model, pinpointing specific bacteria species either promoting or preventing colorectal cancer development. A key aspect of these gut residual bacteria in colorectal cancer development is through exaggerating or easing gut inflammation. Therefore, by taking probiotics composed of corresponding cancer-preventing bacteria from human microbiota, it can be an effective and economic way to reduce human colorectal cancer risks.

The Clinicopathological Correlation of KRAS Mutation and PTEN Expression Status in Primary and Metastatic Colorectal Carcinoma

BACKGROUND

Colorectal cancer (CRC) research has identified a consistent loss of PTEN expression in both primary tumors and metastasis, highlighting its potential role in this disease. However, the impact of PTEN on downstream proteins of KRAS mutation, namely p-AKT, p-ERK, and p65 (NFkB), remains unknown. This study aims to explore the inhibitory effect of PTEN on KRAS downstream proteins and its correlation with pathological features in CRC patients.

METHODS

From January 1, 2015, to December 31, 2021, 86 CRC cases were collected from governmental and private laboratories in the Duhok province. Formalin-fixed, paraffin-embedded tissue blocks were obtained, and the study involved histopathological analysis, immunohistochemistry of PTEN, AKT, ERK, and P65 markers, and molecular analysis of the KRAS gene.

RESULTS

Among the 86 cases, there were 46 males (53.5%) and 40 females (46.5%), with an equal distribution between right colon and left colon/rectum. Tumors larger than 5cm were observed in 47 cases, predominantly displaying a polypoid or ulcerated growth pattern. Most cases were moderately differentiated adenocarcinomas, with stages II and III being the most prevalent 31 cases (36%) and 34 cases (39.5%) respectively. Significant associations were found between PTEN, ERK expressions, and tumor location in the right colon (P=0.031 and P=0.009 respectively). Tumor size correlated with P65 expression (P=0.042). KRAS mutation showed a positive relationship with the type of tumor growth (P=0.035). Tumor grade increased with KRAS mutations (P=0.043). PTEN expression correlated significantly with ERK and AKT markers (P=0.018 and 0.035 respectively). P65 exhibited an association with KRAS mutation (P=0.034).

CONCLUSION

The study revealed PTEN expression in association with the inhibition of AKT and ERK, and the absence of KRAS gene mutation. Conversely, PTEN is not expressed with the positively reactive P65 and the presence of KRAS mutation. This study contributes valuable insights into the complex interplay between PTEN expression, KRAS mutation, and downstream signaling pathways in CRC. It suggests potential avenues for further research and therapeutic strategies in the context of CRC treatment.

IL-1β enhances cell viability and decreases 5-FU sensitivity in novel colon cancer cell lines derived from African American patients

Background

In the U.S., African Americans (AAs) present with the highest incidence and mortality rates for Colorectal Cancer (CRC). When compared to Caucasian American (CA) patients, AAs also have reduced response to the first line standard of care chemotherapeutic agent 5-Fluorouracil (5-FU). Previously, we observed differential gene expression between the two populations, suggesting that colon tumors from AA patients display a decreased antitumor immune response and an increased expression of genes encoding proteins involved in inflammatory processes, such as Interleukin-1β (IL-1β). Here, we investigate the role of IL-1β in modifying chemotherapeutic response and altering expression of proteins in novel AA and well-established CA colon cancer cell lines.

Methods

RNA sequencing analysis was performed to detect expression of genes involved in inflammation in AA and CA colon cancer cells. The effects of IL-1β on 5-FU response was evaluated by assessing cell viability (MTS assay) and apoptosis (flow cytometry analysis) following treatment with 5-FU alone or in combination with the cytokine. Further, we used an IL-1 receptor antagonist (IL-1Ra) to inhibit IL-1β-induced effects on 5-FU sensitivity and NF-kB pathway activation.

Results

AA colon cancer cell lines present significant increase in expression of genes IL1R2 (373-fold change (FC), IRAK1 (3.24 FC), IKBKB, (5.33 FC) NF-KB IA (5.95 FC), MYD88, (3.72 FC), IRAK3 (161 FC), TRAF5 (4.1 FC). A significant decrease in the response to 5-FU treatment, as well as a significant increase in phosphorylation of IκBα and secretion of IL-8, was seen following IL-1β treatment, in both AA and CA cell lines. Finally, treatment with IL-1Ra was able to reverse the effects induced by IL-1β, by increasing the cells sensitivity to 5-FU. IL-1Ra also inhibited phosphorylation of IκBα and IL-8 secretion.

Conclusions

Our results suggest a differential expression of inflammatory genes and proteins that might regulate the different response to IL-1β between AA and CA colon cancer cell lines. Our data also demonstrates that IL-1β is involved in modulating 5-FU response in both AA and CA colon cancer cell lines. Further investigation of these mechanisms might help elucidate the differences seen in incidence, mortality and response to therapy in AA colon cancer patients.

Localized Photothermal Ablation Therapy of Obstructive Rectal Cancer Using a Nanofunctionalized Stent in a Mouse Model

The self-expanding metal stent (SEMS) is a versatile, palliative treatment method for unresectable, malignant, non-vascular strictures. Colorectal cancer (CRC) is one of the candidates for the application of the SEMS, in combination with the photothermal ablation (PTA) technique that enhances its therapeutic efficacy. The objective of this study was to investigate the efficacy of stent-mediated PTA therapy in an endoscopy-guided, orthotopic rectal cancer model. A total of 30 of 40 mice with the tumor size of grade 4 were included and were divided into three groups of 10 mice each. Group A underwent a gold nanoparticle (AuNP)-coated SEMS but no near-infrared (NIR) irradiation, group B received an uncoated control SEMS with NIR irradiation, and group C received a AuNP-coated SEMS and NIR irradiation together. Colonoscopy and in vivo imaging, immunohistochemical analysis, and quantitative reverse-transcription polymerase chain reaction of major tumor markers were performed. Stent placement and PTA were technically successful using colonoscopy. The tumor grade reduction after PTA is significant in group C, compared with groups A or B (p < 0.001). Molecular analysis validated this observation with a significantly reduced Mapk1 proliferation marker or increased Jnk expression. Histological analysis confirmed the localized PTA therapy using AuNP-coated SEMS profoundly ablated tumor outgrowth through the stent. Our results indicate that this novel strategy of localized PTA therapy could be a promising option for palliative treatment of CRC and to support prolonged stent patency with a decreased tumor volume.

IRF1 regulates the progression of colorectal cancer via interferon‑induced proteins

Radiation is one of the main methods for the treatment of colorectal cancer (CRC) before or after surgery. However, radiotherapy tolerance of patients with CRC is often a major concern. Interferon regulatory factor 1 (IRF1) is a member of the IRF family and is involved in the development of multiple diseases, including tumors. The present study investigated the role of IRF1 in the development and radiation sensitivity of CRC. Immunohistochemistry was performed to examine the expression levels of IRF1 in tissue samples from patients with CRC, as well as in nude mice. MTT, 5‑ethynyl‑20‑deoxyuridine, colony formation, cell cycle alteration and apoptosis assays were performed in CRC cell lines. Western blotting and immunofluorescence were used to detect the expression levels of a series of proteins. RNA sequencing was applied to identify genes whose expression was upregulated by IRF1 overexpression. Xenograft nude mouse models and hematoxylin and eosin staining were used to validate the present findings in vivo. It was revealed that the expression levels of IRF1 were significantly lower in CRC tissues than in adjacent tissues. IRF1 upregulation inhibited cell proliferation and colony formation, caused G1 cell arrest, promoted cell apoptosis, and enhanced the sensitivity of CRC cells to X‑ray irradiation. The role of IRF1 in promoting the radiosensitivity of CRC was further demonstrated in nude mice with CRC xenografts. In addition, RNA sequencing revealed that overexpression of IRF1 in CRC cells significantly increased the expression levels of interferon‑induced protein family members interferon α inducible protein 6, interferon induced transmembrane protein 1 and interferon induced protein 35 (fold change >2.0). In summary, the present study demonstrated that the upregulation of IRF1 inhibited the progression and promoted the radiosensitivity of CRC, likely by regulating interferon‑induced proteins.

Interplay between the Gut Microbiota and Inflammatory Mediators in the Development of Colorectal Cancer

Inflammatory mediators modulate inflammatory pathways during the development of colorectal cancer. Inflammatory mediators secreted by both immune and tumor cells can influence carcinogenesis, progression, and tumor metastasis. The gut microbiota, which colonize the entire intestinal tract, especially the colon, are closely linked to colorectal cancer through an association with inflammatory mediators such as tumor necrosis factor, nuclear factor kappa B, interleukins, and interferons. This association may be a potential therapeutic target, since therapeutic interventions targeting the gut microbiota have been actively investigated in both the laboratory and in clinics and include fecal microbiota transplantation and probiotics.