Cellular senescence is associated with the spatial evolution toward a higher metastatic phenotype in colorectal cancer.

In this study, we explore the dynamic process of colorectal cancer progression, emphasizing the evolution toward a more metastatic phenotype. The term "evolution" as used in this study specifically denotes the phenotypic transition toward a higher metastatic potency from well-formed glandular structures to collective invasion, ultimately resulting in the development of cancer cell buddings at the invasive front. Our findings highlight the spatial correlation of this evolution with tumor cell senescence, revealing distinct types of senescent tumor cells (types I and II) that play different roles in the overall cancer progression. Type I senescent tumor cells (p16INK4A+/CXCL12+/LAMC2-/MMP7-) are identified in the collective invasion region, whereas type II senescent tumor cells (p16INK4A+/CXCL12+/LAMC2+/MMP7+), representing the final evolved form, are prominently located in the partial-EMT region. Importantly, type II senescent tumor cells associate with local invasion and lymph node metastasis in colorectal cancer, potentially affecting patient prognosis.

Senescent tumor cells in colorectal cancer are characterized by elevated enzymatic activity of complexes 1 and 2 in oxidative phosphorylation.

BACKGROUND: Cellular senescence is defined as an irreversible cell cycle arrest caused by various internal and external insults. While the metabolic dysfunction of senescent cells in normal tissue is relatively well-established, there is a lack of information regarding the metabolic features of senescent tumor cells. METHODS: Publicly available single-cell RNA-sequencing data from the GSE166555 and GSE178341 datasets were utilized to investigate the metabolic features of senescent tumor cells. To validate the single-cell RNA-sequencing data, we performed senescence-associated ß-galactosidase (SA-ß-Gal) staining to identify senescent tumor cells in fresh frozen colorectal cancer tissue. We also evaluated nicotinamide adenine dinucleotide dehydrogenase-tetrazolium reductase (NADH-TR) and succinate dehydrogenase (SDH) activity using enzyme histochemical methods and compared the staining with SA-ß-Gal staining. MTT assay was performed to reveal the complex 1 activity of the respiratory chain in in-vitro senescence model. RESULTS: Single-cell RNA-sequencing data revealed an upregulation in the activity of complexes 1 and 2 in oxidative phosphorylation, despite overall mitochondrial dysfunction in senescent tumor cells. Both SA-ß-Gal and enzyme histochemical staining using fresh frozen colorectal cancer tissues indicated a high correlation between SA-ß-Gal positivity and NADH-TR/SDH staining positivity. MTT assay showed that senescent colorectal cancer cells exhibit higher absorbance in 600 nm wavelength. CONCLUSIONS: Senescent tumor cells exhibit distinct metabolic features, characterized by upregulation of complexes 1 and 2 in the oxidative phosphorylation pathway. NADH-TR and SDH staining represent efficient methods for detecting senescent tumor cells in colorectal cancer.

p15INK4B is an alternative marker of senescent tumor cells in colorectal cancer.

Senescent tumor cells are nonproliferating tumor cells which are closely related to cancer progression by secreting senescence-related molecules, called senescence-associated secreting phenotypes. Therefore, the presence of senescent tumor cells is considered a prognostic factor in various cancer types. Although senescence-associated ß-galactosidase staining is considered the best marker for detection of senescent tumor cells, it can only be performed in fresh-frozen tissues. p16INK4A, a cyclin-dependent inhibitor, has been used as an alternative marker to detect senescent tumor cells in formalin-fixed paraffin-embedded tissues. However, other reliable markers to detect senescent tumor cells is still lacking. In the present study, using public single-cell RNA-sequencing data, we found that p15INK4B, a cyclin-dependent kinase inhibitor, is a novel marker for detection of senescent tumor cells. Moreover, p15INK4B expression was positively correlated with that of p16INK4A in colorectal cancer tissues. In in vitro studies, mRNA expression of p15INK4B was increased together with that of p16INK4A in H2O2- and therapy-induced cancer senescence models. However, the mRNA level of p15INK4B did not increase in the oncogene-induced senescence model in primary colonic epithelial cells. In conclusion, p15INK4B is a potential alternative marker for detection of senescent tumor cells together with conventional markers in advanced stages of colorectal cancer.

Prognostic Reappraisal of Postoperative Carcinoembryonic Antigen in T1-2N0 Colorectal Cancer.

BACKGROUND/AIM: The purpose of this study was to compare the prognostic value of preoperative carcinoembryonic antigen (CEA), preoperative CEA/tumor size and postoperative CEA in stage I colorectal cancer. PATIENTS AND METHODS: We analyzed a total of 305 consecutive stage I colorectal cancer patients who underwent a radical surgery at our Department. The patients were divided into low and high preoperative CEA groups, low and high preoperative CEA/tumor size groups, and low and high postoperative CEA groups according to the optimal cut-off values. RESULTS: Multivariate analysis showed that postoperative CEA was independently associated with OS and DFS. However, the preoperative CEA and preoperative CEA/tumor size were not. CONCLUSION: The prognostic value of postoperative CEA is better than preoperative CEA and preoperative CEA/tumor size in patients with stage I colorectal cancer. Moreover, the common 5 ng/ml cut-off was not optimal for risk stratification in stage I colorectal cancer.

Prognostic value of changes in serum carcinoembryonic antigen levels for preoperative chemoradiotherapy response in locally advanced rectal cancer.

BACKGROUND: Preoperative chemoradiotherapy (CRT) is a standard treatment modality for locally advanced rectal cancer. However, CRT alone cannot improve overall survival. Approximately 20% of patients with CRT-resistant tumors show disease progression. Therefore, predictive factors for treatment response are needed to identify patients who will benefit from CRT. We theorized that the prognosis may vary if patients are classified according to pre- to post-CRT changes in carcinoembryonic antigen (CEA) levels. AIM: To identify patients with locally advanced rectal cancer for preoperative chemoradiotherapy based on carcinoembryonic antigen levels. METHODS: We retrospectively included locally advanced rectal cancer patients who underwent preoperative CRT and curative resection between 2011 and 2017. Patients were assigned to groups A, B, and C based on pre- and post-CRT serum CEA levels: Both > 5; pre > 5 and post ≤ 5; and both ≤ 5 ng/mL, respectively. We compared the response to CRT based on changes in serum CEA levels. Receiver operating characteristic curve analysis was performed to determine optimal cutoff for neutrophil-lymphocyte ratio and platelet-lymphocyte ratio. Multivariate logistic regression analysis was used to evaluate the prognostic factors for pathologic complete response (pCR)/good response. RESULTS: The cohort comprised 145 patients; of them, 27, 43, and 65 belonged to groups A, B, and C, respectively, according to changes in serum CEA levels before and after CRT. Pre- (P < 0.001) and post-CRT (P < 0.001) CEA levels and the ratio of down-staging (P = 0.013) were higher in Groups B and C than in Group A. The ratio of pathologic tumor regression grade 0/1 significantly differed among the groups (P = 0.003). Group C had the highest number of patients showing pCR (P < 0.001). Most patients with pCR showed pre- and post-CRT CEA levels < 5 ng/mL (P < 0.001, P = 0.008). Pre- and post-CRT CEA levels were important risk factors for pCR (OR = 18.71; 95%CI: 4.62-129.51, P < 0.001) and good response (OR = 5.07; 95%CI: 1.92-14.83, P = 0.002), respectively. Pre-CRT neutrophil-lymphocyte ratio and post-CRT T ≥ 3 stage were also prognostic factors for pCR or good response. CONCLUSION: Pre- and post-CRT CEA levels, as well as change in CEA levels, were prognostic markers for treatment response to CRT and may facilitate treatment individualization for rectal cancer.

Colorectal Cancer in Octogenarian and Nonagenarian Patients: Clinicopathological Features and Survivals.

PURPOSE: Elderly population will comprise a substantial proportion of colorectal cancer (CRC) patients. We examined patients older than 80 years according to their clinical and pathological characteristics to fully understand the elderly patients. METHODS: CRC patients, 60 years or older at diagnosis, admitted between 2009 and 2014 at our hospital were enrolled. The patients were divided into 2 groups: elderly (aged > 80 years, n = 133), and controls (aged 60 to 79 years, n = 596). Patient's demographics, risk factors for prognosis of CRC, Clinicopathological parameters, treatment, and survival rates were compared. RESULTS: The mean ages were 83.9 and 64.8 years, respectively. Male-to-female ratio and tumor sidedness were comparable in both groups. Prognostic factors found in univariate analysis; differentiation, stage, lymphovascular invasion, and carcinoembryonic antigen showed no statistical difference. The microsatellite instability status and number of retrieved lymph nodes were also similar (17.2 vs 21.6, P = 0.505). A significant difference was found in the treatment approach for chemotherapy as the elderly patients with stage III and IV tend to have omitted adjuvant (43.6% vs. 92.8%, P < 0.001) or palliative (35.8% vs. 89.4%, P = 0.016) chemotherapy. Except in stage I, elderly patients showed significantly lower overall survival rates. CONCLUSION: Current study shows far-elderly patients with CRC were less likely to receive standard treatments, which might have resulted in an inferior outcome. As the number of elderly patients with CRC increase, our results provide a basis for further clinical and molecular investigations of elderly CRC patients.

Preoperative neutrophil to lymphocyte ratio predicts survival in patients with T1-2N0 colorectal cancer.

PURPOSE: Neutrophil to lymphocyte ratio (NLR) is reported to be associated with prognosis of colorectal cancer. The aim of this study is to determine whether the NLR is a predictor of oncological outcomes in patients with stage I colorectal cancer who underwent curative surgery. METHODS: Two hundred sixty-nine patients with stage I colorectal cancer who underwent surgical resection between December 2003 and December 2011 were retrospectively reviewed. The cutoff for NLR was defined as three by maximizing log-rank test statistics. We compared patients with a low NLR and those with a high NLR in terms of survival. RESULTS: The 5-year disease-free survival (DFS) and cancer-specific survival (CSS) rates were lower in patients with a high NLR compared to those with a low NLR in stage I colorectal cancer (89.5% vs. 97.4%, P = 0.006; 94.0% vs. 98.9%, P = 0.022). Cox multivariate analysis demonstrated that preoperative NLR was independently associated with DFS (HR, 5.216; 95%CI, 1.400-19.431; P = 0.014) and CSS (HR, 6.190; 95%CI, 1.034-37.047; P = 0.046) in patients with stage I colorectal cancer. CONCLUSION: The preoperative NLR is a prognostic factor predicting DFS and CSS in patients with stage I colorectal cancer who underwent curative surgery.