BRAF V600E-induced distinct DNA damage response defines the therapeutic potential of p53 activation for TP53 wild-type colorectal cancer.

BRAF V600E, one of the most frequent mutations in the MAPK pathway, confers poor prognosis to colorectal cancers (CRCs), partly because of chemotherapeutic resistance. Oncogene-induced DNA damage responses (DDRs) that primarily activate p53 are important mechanistic barriers to the malignant transformation of cells; however, the mechanism underlying this impairment in cancer remains unknown. Here, we evaluated the responses of BRAFV600E-induced DDRs in two CRC cell lines, SW48 and LIM1215, both of which harbor wild-type TP53, KRAS, and BRAF. BRAFV600E transduction exhibited distinct phenotypes in these cells: SW48 cell proliferation markedly decreased, whereas that of LIM1215 increased. BRAFV600E expression induced the activation of oncogene-induced DDR signaling in SW48 cells, but not in LIM1215 cells, whereas chemotherapeutic agents similarly activated DDRs in both cell lines. Knockdown experiments revealed that these responses in SW48 cells were mediated by p53-p21 pathway activation. Comet assay (both alkaline and neutral) revealed that BRAFV600E increased single-strand breaks to the same extent in both cell lines; however, in case of LIM1215 cells, it only facilitated double-strand breaks. Furthermore, the proliferation of LIM1215 cells, wherein no oncogene-induced DDRs occurred, was synergistically inhibited upon MDM2 inhibitor-mediated p53 activation combined with MEK inhibition. Taken together, these distinct DDR signaling responses highlight the novel characteristics of BRAFV600E-mutated CRC cells and define the therapeutic potential of p53 activation combined with MAPK inhibition against TP53 wild-type CRC harboring a BRAFV600E mutation.

Postoperative venous thromboembolism after surgery for locally recurrent rectal cancer.

BACKGROUND: Local recurrence is common after curative resections of rectal cancer. Surgical resection is considered a primary curative treatment option for patients with locally recurrent rectal cancer (LRRC). LRRC often requires a combined resection of other organs, especially in the case of posterior recurrence, which requires a combined resection of the sacrum, making the surgery highly invasive. Venous thromboembolism (VTE) is one of the lethal complications in the postoperative period, particularly in the field of pelvic surgery. We found no reports regarding the risks of postoperative VTE in surgery for LRRC, a typical highly invasive procedure in the field of colorectal surgery. This study aims to evaluate the risk of postoperative VTE in surgery for LRRC patients. METHODS: From April 2010 to March 2022, a total of 166 patients underwent surgery for LRRC in the pelvic region at our institutions. Clinicopathological background and VTE incidence were compared retrospectively. RESULTS: Among the 166 patients included in the study, 55 patients (33.1%) needed sacral resection. Pharmacological prophylaxis for prevention of VTE was performed in 121 patients (73.3%), and the incidence of VTE was 9.09% (5/55 patients) among those who underwent surgery for LRRC with sacral resection, while it was 1.8% (2/111 patients) in those without sacral resection. In univariate analysis, the combination with sacral resection was identified as a risk factor for VTE in surgery for LRRC (p = 0.047). CONCLUSIONS: This study demonstrates that surgery for LRRC combined with sacral resection could be a significant risk factor for VTE.

Assessing risk factors for elevated creatine kinase levels as an indicator of compartment syndrome following laparoscopic or robot-assisted colorectal cancer surgery in the lithotomy-trendelenburg position.

BACKGROUND: Well-leg compartment syndrome (WLCS) can occur due to compression and lower limb circulation disturbances caused by the surgical position during the procedure. Although rare, with an incidence of 1 in 3500 surgeries performed in the lithotomy position, it can lead to serious complications. Therefore, prevention and early diagnosis are critical. Symptoms of WLCS, such as leg pain, swelling, paresthesia, and serum creatine kinase (CK) levels are useful for diagnosis. This study aimed to investigate the risk factors for postoperative CK elevation in laparoscopic or robot-assisted colorectal cancer surgery performed in the lithotomy-Trendelenburg position. METHODS: Postoperative CK levels were measured in 178 patients who underwent laparoscopic or robot-assisted colorectal cancer surgery between February 2022 and March 2023. We compared patient backgrounds, short-term outcomes, and thigh/calf circumferences between patients with CK levels ≥ 250 (n = 62) and those with CK levels < 250 (n = 116). We investigated risk factors for elevated CK levels using both univariate and multivariate analyses. RESULTS: Four patients with CK levels of 22405 U/L, 4685 U/L, 4050 U/L, and 3824 U/L reported symptoms, which improved with conservative treatment. The following independent prognostic factors were identified by multivariate analysis: male sex (odds ratio [OR], 4.403; 95% CI, 1.960 to 9.892), rectal surgery (OR, 2.779; 95% CI, 1.249 to 6.184), continuous head-down position duration ≥ 180 min (OR, 3.523; 95% CI, 1.552 to 7.997), and preoperative calf circumference ≥ 33 cm (OR, 2.482; 95% CI, 1.154 to 5.339). CONCLUSIONS: Risk factors for CK elevation after colorectal cancer surgery in the lithotomy position include male sex, rectal surgery, an extended continuous head-down position without position changes, and a larger preoperative calf circumference. This study highlights the potential importance of intraoperative position changes every 3 h for preventing elevated CK levels, although the preventive effect was not specifically examined.

Cancer-specific tissue-resident memory T-cells express ZNF683 in colorectal cancer.

BACKGROUND: Tissue-resident memory T (Trm) cells are associated with cytotoxicity not only in viral infection and autoimmune disease pathologies but also in many cancers. Tumour-infiltrating CD103+ Trm cells predominantly comprise CD8 T cells that express cytotoxic activation and immune checkpoint molecules called exhausted markers. This study aimed to investigate the role of Trm in colorectal cancer (CRC) and characterise the cancer-specific Trm. METHODS: Immunochemical staining with anti-CD8 and anti-CD103 antibodies for resected CRC tissues was used to identify the tumour-infiltrating Trm cells. The Kaplan-Meier estimator was used to evaluate the prognostic significance. Cells immune to CRC were targeted for single-cell RNA-seq analysis to characterise cancer-specific Trm cells in CRC. RESULTS: The number of CD103+/CD8+ tumour-infiltrating lymphocytes (TILs) was a favourable prognostic and predictive factor of the overall survival and recurrence-free survival in patients with CRC. Single-cell RNA-seq analysis of 17,257 CRC-infiltrating immune cells revealed a more increased zinc finger protein 683 (ZNF683) expression in cancer Trm cells than in noncancer Trm cells and in high-infiltrating Trm cells than low-infiltrating Trm in cancer, with an upregulated T-cell receptor (TCR)- and interferon-γ (IFN-γ) signalling-related gene expression in ZNF683+ Trm cells. CONCLUSIONS: The number of CD103+/CD8+ TILs is a prognostic predictive factor in CRC. In addition, we identified the ZNF683 expression as one of the candidate markers of cancer-specific Trm cells. IFN-γ and TCR signalling and ZNF683 expression are involved in Trm cell activation in tumours and are promising targets for cancer immunity regulation.

Cancer Stem Cells Persist Despite Cellular Damage, Emergence of the Refractory Cell Population.

PURPOSE: Cancer stem cells (CSCs) are responsible for chemotherapy resistance and have unique properties that protect them from chemotherapy. Investigating CSCs may help to identify the population that is more resistant to treatments, leading to recurrence. We evaluated persisting CSCs, emerging after chemotherapy that cause tumor recurrence. METHODS: Using human colorectal cancer organoids prepared from surgical specimens, we looked at changes in CSCs, the emergence and changes in the original population, which single-cell analysis identified. RESULTS: With regards to changes in cancer stem cell markers, CD44 showed low levels after 5-fluorouracil administration. Once the CD44-ve population was sorted and cultured, the CD44+ve population gradually emerged, and the CD44-ve population decreased. Compared with the CD44-ve population of an organoid parent, the CD44-ve population proliferated after chemotherapeutic agent stimulation. The CD44-ve population was derived from the CD44+ve population before chemotherapeutic agents. In addition, when the CD44 variants were evaluated, the CD44v9 population remained. In single-cell analysis, we found that POU5F1 was highly expressed in the CD44low population. Velocity analysis showed that the CD44-ve population was induced after chemotherapy and expressed POU5F1. POU5F1-EGFP-Casp9 transfected organoids resulted in the appearance of a CD44-ve population after administration of a chemotherapeutic reagent. Both in vivo and in vitro, the dimerizer administration inhibited tumor growth significantly. CONCLUSIONS: POU5F1 is involved in chemotherapy resistance in relation to stemness. For the treatment against refractory tumors, such as the recurrence after chemotherapy, the treatment should target the emerging specific population such as CD44 (or CD44v9) and proliferative cancer cells.

Clinical Significance of Preoperative and Postoperative Serum CEA and Carbohydrate Antigen 19-9 Levels in Patients Undergoing Curative Resection of Locally Recurrent Rectal Cancer.

BACKGROUND: Local recurrence is common after curative resection for rectal cancer. Although one expects radical resection of locally recurrent rectal cancer to be curative, the postoperative re-recurrence rate is relatively high. Therefore, identifying risk factors for recurrence may improve the prognosis of locally recurrent rectal cancer with early therapeutic intervention. OBJECTIVE: This study aimed to evaluate the relationship between perioperative serum CEA/carbohydrate antigen 19-9 levels and prognosis in locally recurrent rectal cancer to validate their usefulness for postoperative surveillance in locally recurrent rectal cancer. DESIGN: This was a single-center retrospective cohort study. SETTING: The study is based on data obtained from procedures at the Osaka University Hospital. PATIENTS: Ninety patients underwent radical resection for locally recurrent rectal cancer between January 2000 and January 2015. MAIN OUTCOME MEASURES: We evaluated the correlation between perioperative serum CEA/carbohydrate antigen 19-9 levels and prognosis after complete resection of locally recurrent rectal cancer and the serum CEA and carbohydrate antigen 19-9 levels at the diagnosis of postoperative re-recurrence. RESULTS: The median preoperative serum CEA level was 4 ng/mL and carbohydrate antigen 19-9 level was 12 U/mL. Of the 90 patients, 43.3% had serum CEA ≥5 ng/mL, and 15.6% had serum carbohydrate antigen 19-9 ≥37 U/mL. Preoperatively, this serum carbohydrate antigen 19-9 level strongly correlated with poorer prognoses regarding cancer-specific survival. Postoperatively, serum CEA ≥5 ng/mL significantly correlated with a worse prognosis. At the time of diagnosis of re-recurrence after resection of locally recurrent rectal cancer, 53.2% of patients had serum CEA ≥5 ng/mL, and 23.4% of patients had serum carbohydrate antigen 19-9 ≥37 U/mL. LIMITATIONS: The study was limited by its single-center retrospective design, an insufficient sample size, and a relatively long study period. CONCLUSIONS: High serum levels of carbohydrate antigen 19-9 preoperatively and CEA postoperatively are associated with poor prognosis after locally recurrent rectal cancer. Furthermore, we found a high rate of serum CEA elevation in the diagnosis of postoperative re-recurrence. See Video Abstract at http://links.lww.com/DCR/C106 . IMPORTANCIA CLNICA DE LOS NIVELES SRICOS PREOPERATORIOS Y POSOPERATORIOS DE CEA Y CA EN PACIENTES SOMETIDOS A RESECCIN CURATIVA DE CNCER DE RECTO LOCALMENTE RECURRENTE: ANTECEDENTES:La recurrencia local es común después de la resección curativa del cáncer de recto. Aunque se espera que la resección radical del cáncer rectal localmente recurrente sea curativa, la tasa de recurrencia posoperatoria es relativamente alta. Por lo tanto, la identificación de los factores de riesgo de recurrencia puede mejorar el pronóstico del cáncer de recto localmente recurrente con una intervención terapéutica temprana.OBJETIVO:Evaluamos la relación entre los niveles séricos perioperatorios de CEA/CA19-9 y el pronóstico en el cáncer de recto localmente recurrente para validar su utilidad para la vigilancia posoperatoria en el cáncer de recto localmente recurrente.DISEÑO:Este fue un estudio de cohorte retrospectivo de un solo centro.AJUSTE:El estudio se basa en datos obtenidos de procedimientos en el Hospital Universitario de Osaka.PACIENTES:Noventa pacientes fueron sometidos a resección radical por cáncer de recto localmente recurrente entre Enero de 2000 y Enero de 2015.PRINCIPALES MEDIDAS DE RESULTADOS:Evaluamos la correlación entre los niveles séricos perioperatorios de CEA/CA19-9 y el pronóstico después de la resección completa del cáncer de recto localmente recurrente y los niveles séricos de CEA y CA19-9 en el diagnóstico de recurrencia posoperatoria.RESULTADOS:La mediana de los niveles séricos preoperatorios de CEA y CA19-9 fueron de 4 ng/mL y 12 U/mL, respectivamente. De los 90 pacientes, el 43,3 % tenía CEA sérico ≥5 ng/mL y el 15,6 % tenía CA19-9 sérico ≥37 U/mL. Antes de la operación, este nivel sérico de CA19-9 se correlacionó fuertemente con peores pronósticos con respecto a la supervivencia específica del cáncer. Después de la operación, el CEA sérico ≥5 ng/mL se correlacionó significativamente con un peor pronóstico. En el momento del diagnóstico de recurrencia después de la resección del cáncer de recto localmente recurrente, el 53,2 % de los pacientes tenían CEA sérico ≥5 ng/mL y el 23,4 % de los pacientes tenían CA19-9 sérico ≥37 U/mL.LIMITACIONES:El estudio estuvo limitado por su diseño retrospectivo de un solo centro, un tamaño de muestra insuficiente y un período de estudio relativamente largo.CONCLUSIONES:Los niveles séricos altos de CA19-9 antes de la operación y de CEA después de la operación están asociados con un mal pronóstico después del cáncer de recto localmente recurrente. Además, encontramos una alta tasa de elevación del CEA sérico en el diagnóstico de recurrencia posoperatoria. Consulte el Video Resumen en http://links.lww.com/DCR/C106 . (Traducción-Dr. Yesenia Rojas-Khalil ).

Simple Detection and Culture of Circulating Tumor Cells from Colorectal Cancer Patients Using Poly(2-Methoxyethyl Acrylate)-Coated Plates.

Here we aimed to establish a simple detection method for detecting circulating tumor cells (CTCs) in the blood sample of colorectal cancer (CRC) patients using poly(2-methoxyethyl acrylate) (PMEA)-coated plates. Adhesion test and spike test using CRC cell lines assured efficacy of PMEA coating. A total of 41 patients with pathological stage II-IV CRC were enrolled between January 2018 and September 2022. Blood samples were concentrated by centrifugation by the OncoQuick tube, and then incubated overnight on PMEA-coated chamber slides. The next day, cell culture and immunocytochemistry with anti-EpCAM antibody were performed. Adhesion tests revealed good attachment of CRCs to PMEA-coated plates. Spike tests indicated that ~75% of CRCs from a 10-mL blood sample were recovered on the slides. By cytological examination, CTCs were identified in 18/41 CRC cases (43.9%). In cell cultures, spheroid-like structures or tumor-cell clusters were found in 18/33 tested cases (54.5%). Overall, CTCs and/or growing circulating tumor cells were found in 23/41 CRC cases (56.0%). History of chemotherapy or radiation was significantly negatively correlated with CTC detection (p = 0.02). In summary, we successfully captured CTCs from CRC patients using the unique biomaterial PMEA. Cultured tumor cells will provide important and timely information regarding the molecular basis of CTCs.

[A Case of Squamous Cell Carcinoma of the Lower Rectum].

A 61-year-old man presented with dyschezia, and further examination revealed squamous cell carcinoma of the lower rectum invading the bladder and seminal vesicles. The clinical diagnosis was squamous cell carcinoma of the lower rectum, cT4b(bladder and seminal vesicle)N0M0, cStage Ⅱc. Neoadjuvant chemoradiotherapy was administered with external irradiation of the entire pelvis(50.4 Gy/28 Fr)and chemotherapy with 5-fluorouracil, Leucovorin, and oxaliplatin(FOLFOX). Once tumor shrinkage was observed 3 months after chemoradiotherapy, laparoscopic total pelvic exenteration with TaTME approach was performed. The patient was discharged on the 26th postoperative day without any postoperative complications. Histopathological examination showed only squamous cell carcinoma component with Grade 1a histological treatment effect. The pathological diagnosis was ypT4b(bladder, seminal vesicle)ypN0cM0, ypStage Ⅱc. The patient was alive without any recurrence 6 months after surgery.

Low G9a expression is a tumor progression factor of colorectal cancer via IL-8 promotion.

The histone methyltransferase G9a is expressed in various types of cancer cells, including colorectal cancer (CRC) cells. Interleukin 8 (IL)-8, also known as C-X-C motif chemokine ligand 8 (CXCL8), is a chemokine that plays a pleiotropic function in the regulation of inflammatory responses and cancer development. Here, we examined the relationship between G9a and IL-8 and the clinical relevance of this association. We immunohistochemically analyzed 235 resected CRC samples to correlate clinical features. Samples with high G9a expression had better overall survival and relapse-free survival than those with low G9a expression. Univariate and multivariate analyses demonstrated that low G9a expression remained a significant independent prognostic factor for increased disease recurrence and decreased survival (P < 0.05). G9a was expressed at high levels in commercially available CRC cell lines HCT116 and HT29. Knockdown of G9a by siRNA, shRNA or the G9a-specific inhibitor BIX01294 upregulated IL-8 expression. The number of spheroids was significantly increased in HCT116 cells with stably suppressed G9a expression, and the number of spheroids was significantly decreased in HCT116 cells with stably suppressed IL-8 expression. Thus, the suppression of IL-8 by G9a may result in a better prognosis in CRC cases with high G9a expression. Furthermore, G9a may suppress cancer stemness and increase chemosensitivity by controlling IL-8. Therefore, G9a is a potential novel marker for predicting CRC prognosis, and therapeutic targeting of G9a in CRC should be controversial.

A stem cell marker KLF5 regulates CCAT1 via three-dimensional genome structure in colorectal cancer cells.

BACKGROUND: KLF5 plays a crucial role in stem cells of colorectum in cooperation with Lgr5 gene. In this study, we aimed to explicate a regulatory mechanism of the KLF5 gene product from a view of three-dimensional genome structure in colorectal cancer (CRC). METHODS: In vitro engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP)-seq method was used to identify the regions that bind to the KLF5 promoter. RESULTS: We revealed that the KLF5 promoter region interacted with the KLF5 enhancer region as well as the transcription start site (TSS) region of the Colon Cancer Associated Transcript 1 (CCAT1) gene. Notably, the heterodeletion mutants of KLF5 enhancer impaired the cancer stem-like properties of CRC cells. The KLF5 protein participated in the core-regulatory circuitry together with co-factors (BRD4, MED1, and RAD21), which constructs the three-dimensional genome structures consisting of KLF5 promoter, enhancer and CCAT1 TSS region. In vitro analysis indicated that KLF5 regulated CCAT1 expression and we found that CCAT1 expression was highly correlated with KLF5 expression in CRC clinical samples. CONCLUSIONS: Our data propose the mechanistic insight that the KLF5 protein constructs the core-regulatory circuitry with co-factors in the three-dimensional genome structure and coordinately regulates KLF5 and CCAT1 expression in CRC.

PLXND1/SEMA3E Promotes Epithelial-Mesenchymal Transition Partly via the PI3K/AKT-Signaling Pathway and Induces Heterogenity in Colorectal Cancer.

Colorectal cancer (CRC) is a major cause of cancer-related deaths. Metastasis is enhanced through epithelial-mesenchymal transition (EMT), a process primarily induced by the transforming growth factor beta (TGF-ß)-mediated canonical Smad pathway. This study focused on plexin D1 (PLXND1), a chemoreceptor for the ligand SEMA3E to mechanosensory, showing that PLXND1 induces EMT via activation of the PI3K/AKT pathway in CRC cells. The findings showed that PLXND1-knockdown decreases cell migration and invasion significantly, and that the binding of p61-SEMA3E to the PLXND1 enhances the invasiveness and migration through EMT. Furin inhibitor suppresses EMT, decreasing cell migration and invasion. Furin cleaves full-length SEMA3E and converts it to p61-SEMA3E, suggesting that furin inhibitors block PLXND1 and p61-SEMA3E binding. Furin is a potential therapeutic target for the purpose of suppressing EMT by inhibiting the binding of p61-SEMA3E to PLXND1. In vivo experiments have shown that PLXND1-knockdown suppresses EMT. Mesenchymal cells labeled with ZEB1 showed heterogeneity depending on PLXND1 expression status. The high-expression group of PLXND1 in 182 CRC samples was significantly associated with poor overall survival compared with the low-expression group (P = 0.0352, median follow-up period of 60.7 months) using quantitative real-time polymerase chain reaction analysis. Further research is needed to determine whether cell fractions with a different expression of PLXND1 have different functions.

Development and evaluation of a Japanese prediction model for low anterior resection syndrome after rectal cancer surgery.

BACKGROUND: Low anterior resection syndrome (LARS) is the most common complication after rectal cancer resection. We aimed to identify LARS' predictive factors and construct and evaluate a predictive model for LARS. METHODS: This retrospective study included patients with rectal cancer more than 1 year after laparoscopic or robotic-assisted surgery. We administered a questionnaire to evaluate the degree of LARS. In addition, we examined clinical characteristics with univariate and multivariate analysis to identify predictive factors for major LARS. Finally, we divided the obtained data into a learning set and a validation set. We constructed a predictive model for major LARS using the learning set and assessed the predictive accuracy of the validation set. RESULTS: We reviewed 160 patients with rectal cancer and divided them into a learning set (n = 115) and a validation set (n = 45). Univariate and multivariate analyses in the learning set showed that male (odds ratio [OR]: 2.88, 95% confidence interval [95%CI] 1.11-8.09, p = 0.03), age < 75 years (OR: 5.87, 95%CI 1.14-47.25, p = 0.03) and tumors located < 8.5 cm from the AV (OR: 7.20, 95%CI 2.86-19.49, p < 0.01) were significantly related to major LARS. A prediction model based on the patients in the learning set was well-calibrated. CONCLUSIONS: We found that sex, age, and tumor location were independent predictors of major LARS in Japanese patients that underwent rectal cancer surgery. Our predictive model for major LARS could aid medical staff in educating and treating patients with rectal cancer before and after surgery.

Fecal Stream Diversion Changes Intestinal Environment, Modulates Mucosal Barrier, and Attenuates Inflammatory Cells in Crohn's Disease.

BACKGROUND: The intestinal environment plays important roles in mucosal barrier homeostasis and intestinal inflammation, as clarified in studies using experimental animals but not in humans. AIMS: We investigated whether environmental changes in the fecal stream cause phenotypic changes in the human mucosal barrier. METHODS: We obtained human ileal samples after fecal stream diversions in patients with rectal cancer or Crohn's disease. We investigated the bacterial load and diversity in the human defunctioned ileum, defined as the anal side of the ileum relative to the ileostomy. We also examined the epithelium and lamina propria cell phenotypes in the defunctioned ileum. RESULTS: After fecal stream diversion, bacterial loads decreased significantly in the defunctioned ileum. Based on the Chao1, Shannon, and observed species indices, the diversity of mucosa-associated microbiota was lower in the defunctioned ileum than in the functional ileum. Moreover, the healthy defunctioned ileum showed reductions in villous height, goblet cell numbers, and Ki-67+ cell numbers. Additionally, interferon-γ+, interleukin-17+, and immunoglobulin A+ cell abundance in the lamina propria decreased. After the intestinal environment was restored with an ileostomy closure, the impaired ileal homeostasis recovered. The defunctioned ileum samples from patients with Crohn's disease also showed reductions in interferon-γ+ and interleukin-17+ cell numbers. CONCLUSIONS: Fecal stream diversion reduced the abundance and diversity of intestinal bacteria. It also altered the intestinal mucosal barrier, similar to the alterations observed in germ-free animals. In patients with Crohn's disease, Th1 and Th17 cell numbers were attenuated, which suggests that the host-microbiome interaction is important in disease pathogenesis.

Locally advanced rectal cancer receiving total neoadjuvant therapy combined with nivolumab: a case report and literature review.

BACKGROUND: The standard treatment for locally advanced rectal cancer (LARC) is preoperative chemoradiotherapy (CRT) followed by surgery and adjuvant chemotherapy. However, it has been suggested that intensification of neoadjuvant treatment with polychemotherapy in addition to CRT instead of as an adjuvant chemotherapy is better tolerated and associated with a higher pathological complete response (pCR) rate. This concept is known as total neoadjuvant therapy (TNT). Recently, the addition of immunotherapy to preoperative CRT has been reported to be useful in LARC patients with mismatch-repair-deficiency and high levels of microsatellite instability (MSI-H), but there are no reports showing the therapeutic effect of nivolumab in combination with TNT. CASE PRESENTATION: A 23-year-old man had frequent diarrhea. Preoperative examination revealed two adenocarcinomas in the rectum. His maternal grandmother had a rectal cancer patient who developed the disease at age 70s. The larger tumor was located at the peritoneal reflection, and its anterior border close to the prostate (<1 mm); there were eight enlarged pararectal lymph nodes. Considering the size and depth of the tumor, it was judged that radical resection with sufficient margins would be difficult. Therefore, it was decided that TNT would be performed. At first, CAPOX (capecitabine and L-OHP) was administered, followed by preoperative CRT (RT:50.4 Gy and capecitabine). During this period, genetic testing diagnosed this patient as MSI-H, so additional nivolumab was administered after CRT. Colonoscopy revealed that the larger tumor was no longer detectable, so robot-assisted intersphincteric resection and bilateral lateral lymph node dissection was performed. The diagnosis of pCR was made for the larger tumor and partial response was achieved for the smaller tumor, and no lymph node metastasis was found. Major complications were not observed and the patient was discharged on the 14th day after surgery. He was followed up without adjuvant chemotherapy and is alive and recurrence-free after 9 months. CONCLUSION: A case of LARC with MSI-H was treated with TNT with nivolumab, resulting in pCR and complete radical resection. This result suggests that nivolumab in addition to TNT can be an option as a preoperative strategy for LARC with MSI-H.

The prediction of postoperative anorectal dysfunction after low anterior resection for lower rectal cancer by measuring the volume of defecation-related muscles.

PURPOSE: Approximately 90% of patients are thought to develop bowel dysfunction after low anterior resection (LAR). Although some prognostic factors have been reported, the volumes of defecation-related muscles have not been examined. This retrospective study investigated the association between the preoperative volume of defecation-related muscles and major LARS. METHODS: Forty-six patients who underwent LAR for rectal cancer between 2013 and 2020 in our institution were analyzed. They had no local residual tumor or local recurrence at the time of the study and no problems with their defecation function pre-operatively. Defecation-related muscle volume measurements were made before surgery, and the patients answered a low anterior resection syndrome (LARS) score questionnaire after surgery. The muscle volume was adjusted by the patient's height squared. RESULTS: Twenty-seven patients (58.7%) developed major LARS. In the univariate analysis, sex, lateral lymph node dissection, and diverting ileostomy as well as muscle volume of the external anal sphincter, pubococcygeal + iliococcygeus muscle, and puborectal muscle were associated with major LARS. In a multivariate analysis, pubococcygeal + iliococcygeus muscle (< 5.96 ml/m2) was the only factor (p = 0.02). CONCLUSIONS: Measuring the volume of the defecation-related muscles may aid in predicting major LARS.

Risk factors for postoperative proximal deep vein thrombosis and pulmonary embolism after laparoscopic colorectal cancer surgery: analysis of a multicenter randomized controlled trial.

PURPOSE: Postoperative venous thromboembolism (VTE) is a major and potentially fatal postoperative complication of colorectal cancer surgery. However, there is uncertainty about the necessity for anticoagulant prophylaxis to prevent VTE after laparoscopic colorectal cancer surgery because of its associated relatively lower incidence. Currently, anticoagulant therapy is considered mainly for patients at high risk of the development of VTE. Focusing on proximal deep vein thrombosis (DVT)/ pulmonary embolism (PE), we aimed to identify those cases at high risk of the development of fatal VTE. METHODS: We performed an exploratory retrospective analysis to identify the risk factors for postoperative proximal DVT and PE after laparoscopic colorectal cancer surgery in patients included in our prospective trial. RESULTS: A logistic regression analysis revealed factors that could predict the onset of proximal DVT/PE in patients with colorectal cancer. Blood loss and tumor location were identified as the predictors of proximal DVT/PE. CONCLUSIONS: Patients with rectal cancer and those with excessive blood loss during colon cancer surgery must be monitored carefully for signs of VTE and especially proximal DVT/PE, after laparoscopic surgery.

Postoperative pain management after concomitant sacrectomy for locally recurrent rectal cancer.

PURPOSE: To assess pain management in patients post-sacrectomy, focusing on opioid use, and to identify the factors associated with postoperative pain. METHODS: Patients who underwent resection of locally recurrent rectal cancer (LRRC) with concomitant sacrectomy at one of two hospitals between 2007 and 2020 were reviewed retrospectively. We examined the use of opioids preoperatively and postoperatively. Patients were classified into high and low sacrectomy groups based on the sacral bone resection level passing through the S3 vertebra. RESULTS: Sixty-four patients were enrolled. Opioid use was significantly higher in the high sacrectomy group than in the low sacrectomy group at all times assessed: on postoperative days 7, 14, 30, 90, 180, and 365. Opioid use 3 months after locally recurrent rectal cancer surgery was significantly higher in patients with local re-recurrence of the tumor than in those without re-recurrence (p < 0.05), and the median morphine-equivalent opioid use 3 months postoperatively was significantly higher in the high sacrectomy group (30 vs. 0 mg/day; p < 0.05). CONCLUSIONS: Opioid use after concomitant sacrectomy for LRRC was higher in the high sacrectomy group. Prolonged postoperative pain or increasing pain was associated with local recurrence.

[Perineal Wound Complications after Abdominoperineal Resection for Anorectal Lesions].

BACKGROUND: Perineal wound complications(PWCs)are common after abdominoperineal resection(APR). We examined the incidence of PWCs after APR for anorectal lesions and their risk factors. METHODS: Patients who underwent APR for anorectal lesions at our hospital from January 2011 to December 2021 were included. Complications of Clavien-Dindo Grade Ⅱ or higher were considered as PWCs. RESULTS: Eighty-one patients were included; PWCs were observed in 24 patients (29.6%), and associated with a history of Crohn's disease(p=0.018), longer operation time(p=0.040), higher blood loss (p=0.011), extensive perineal resection(p=0.003), and closure with a skin flap(p=0.003). Forty-one patients underwent APR for initial rectal cancer without extended perineal resection, and PWCs were observed in 9 patients(22.0%). Prognostic nutritional index(PNI)<45(p=0.049), smoking(p=0.034), and alcohol consumption(p=0.021)were associated with PWCs. CONCLUSION: We examined the incidence of PWCs after APR for anorectal lesions and their risk factors. Appropriate intervention in nutrition, smoking, and alcohol consumption may prevent PWCs.

Specific activation of glycolytic enzyme enolase 2 in BRAF V600E-mutated colorectal cancer.

The BRAF V600E mutation occurs in approximately 10% of patients with metastatic colorectal cancer (CRC) and constitutes a distinct subtype of the disease with extremely poor prognosis. To address this refractory disease, we investigated the unique metabolic gene profile of BRAF V600E-mutated tumors via in silico analysis using a large-scale clinical database. We found that BRAF V600E-mutated tumors exhibited a specific metabolic gene expression signature, including some genes that are associated with poor prognosis in CRC. We discovered that BRAF V600E-mutated tumors expressed high levels of glycolytic enzyme enolase 2 (ENO2), which is mainly expressed in neuronal tissues under physiological conditions. In vitro experiments using CRC cells demonstrated that BRAF V600E-mutated cells exhibited enhanced dependency on ENO2 compared to BRAF wild-type cancer cells and that knockdown of ENO2 led to the inhibition of proliferation and migration of BRAF V600E-mutated cancer cells. Moreover, inhibition of ENO2 resulted in enhanced sensitivity to vemurafenib, a selective inhibitor of BRAF V600E. We identified AP-1 transcription factor subunit (FOSL1) as being involved in the transcription of ENO2 in CRC cells. In addition, both MAPK and PI3K/Akt signaling were suppressed upon inhibition of ENO2, implying an additional oncogenic role of ENO2. These results suggest the crucial role of ENO2 in the progression of BRAF V600E-mutated CRC and indicate the therapeutic implications of targeting this gene.

SIRT3-Mediated SOD2 and PGC-1α Contribute to Chemoresistance in Colorectal Cancer Cells.

BACKGROUND: Anticancer drugs generate excessive reactive oxygen species (ROS), which can cause cell death. Cancer cells can resist this oxidative stress, but the mechanism of resistance and associations with chemoresistance are unclear. Here, we focused on Sirtuin 3 (SIRT3), a deacetylating mitochondrial enzyme, in oxidative stress resistance in colorectal cancer (CRC). METHODS: To evaluate SIRT3-related changes in mitochondrial function, ROS (mtROS) induction, and apoptosis, we used the human CRC cell lines HT29 and HCT116 transfected with short-hairpin RNA targeting SIRT3 and small interfering RNAs targeting superoxide dismutase 2 mitochondrial (SOD2) and peroxisome proliferator-activated receptor γ coactivator-1 (PGC-1α). In 142 clinical specimens from patients with CRC, we also assessed the association of SIRT3 protein levels (high/low) and prognosis. RESULTS: SIRT3 expression correlated with mtROS generation and apoptosis induction in cells treated with anticancer agents. Suppressing SIRT3 increased mtROS levels and cell sensitivity to anticancer agents. SIRT3 knockdown decreased SOD2 expression and activity, and suppressing SOD2 also improved sensitivity to anticancer drugs. In addition, SIRT3 was recruited with PGC-1α under oxidative stress, and suppressing SIRT3 decreased PGC-1α expression and mitochondrial function. PGC-1α knockdown decreased mitochondrial activity and increased apoptosis in cells treated with anticancer drugs. In resected CRC specimens, high vs low SIRT3 protein levels were associated with significantly reduced cancer-specific survival. CONCLUSIONS: SIRT3 expression affected CRC cell chemoresistance through SOD2 and PGC-1α regulation and was an independent prognostic factor in CRC. SIRT3 may be a novel target for CRC therapies and a predictive marker of sensitivity to chemotherapy.