A novel protein encoded by circINSIG1 reprograms cholesterol metabolism by promoting the ubiquitin-dependent degradation of INSIG1 in colorectal cancer.

BACKGROUND: Hypoxia is a hallmark of solid tumors and leads to the metabolic reprogramming of cancer cells. The role of epigenetic regulation between hypoxia and aberrant cholesterol metabolism in colorectal cancer (CRC) remains elusive. METHODS: Hypoxia-responsive circular RNAs (circRNAs) were identified by high throughput RNA sequencing between CRC cells cultured under normoxia or hypoxia. The protein-coding potential of circINSIG1 was identified by polysome profiling and LC-MS. The function of circINSIG1 was validated in vitro and in vivo by gain or loss of function assays. Mechanistic results were concluded by immunoprecipitation analyses. RESULTS: A novel hypoxia-responsive circRNA named circINSIG1 was identified, which was upregulated in CRC tissues and correlated with advanced clinical stages and poor survival. Mechanistically, circINSIG1 encoded a 121 amino acid protein circINSIG1-121 to promote K48-linked ubiquitination of the critical cholesterol metabolism regulator INSIG1 at lysine 156 and 158 by recruiting CUL5-ASB6 complex, a ubiquitin E3 ligase complex, thereby inducing cholesterol biosynthesis to promote CRC proliferation and metastasis. The orthotopic xenograft tumor models and patient-derived xenograft models further identified the role of circINSIG1 in CRC progression and potential therapeutic target of CRC. CONCLUSIONS: circINSIG1 presents an epigenetic mechanism which provides insights into the crosstalk between hypoxia and cholesterol metabolism, and provides a promising therapeutic target for the treatment of CRC.

Improvement of low anterior resection syndrome beyond 2 years after total mesorectal excision.

AIM: Bowel dysfunction after sphincter-preserving proctectomy, also known as low anterior resection syndrome (LARS), has significant impact on survivors of rectal cancer. This study aimed to assess the temporal change of LARS beyond 2 years after proctectomy, which has not been fully studied. METHODS: We longitudinally enrolled consecutive patients who had received total mesorectal excision in a tertiary academic medical center, with preoperative neoadjuvant therapy if indicated. LARS score was longitudinally assessed by two serial follow-ups, with a fixed interval of 18 months. RESULTS: Overall, 107 patients responded for the first follow-up after a median of q20 months, 96 of whom responded for the second follow-up after a median of 38 months. At the first follow-up, 48 patients (44.9%) reported major LARS, compared with 23 (24.0%) at the second follow-up (p < 0.001). Mean LARS score improved from 27.3 to 18.6, mostly from "urgency" (12.2 vs. 6.2, p < 0.001) and "clustering of stools" (9.7 vs. 7.7, p = 0.001). Anastomosis less than 3 cm from the anal verge was independently associated with LARS improvement. CONCLUSION: Bowel dysfunction continues to improve 2 years after total mesorectal excision, with most symptom relief in urgency and stool clustering, especially in patients with lower anastomosis.

Survival after curative resection for stage I colorectal mucinous adenocarcinoma.

PURPOSE: The prognostic value of the mucinous adenocarcinoma histotype on the early stages especially for stage I colorectal cancer (CRC) is still unclear. This study determined the clinicopathologic characteristics and long-term outcome of stage I colorectal mucinous adenocarcinomas (MAC). METHODS: Among the total of 530 patients with stage I CRC (58 having MAC and 472 having non-MAC) who underwent radical resection, the correlation between clinicopathological factors and MAC was analyzed. Multivariate analysis was performed to determine whether mucinous histotype itself was an independent prognostic impact in stage I patients. RESULTS: MACs were observed more frequently located in the colon than rectum (p = 0.049), more frequently displayed the deficient mismatch repair (dMMR) phenotype (p = 0.001) and had a greater frequency of T2 stage (p = 0.002). The rate of recurrence was 15.3% and the mortality was 9.2% among all stage I CRC patients. There was no difference in disease-free survival and overall survival between MACs and non-MACs. On multivariate analysis, older age (p = 0.009, hazard ratio: 2.22), rectal cancer (p = 0.008, hazard ratio: 3.21), lymphovascular invasion (LVI) (p < 0.001, hazard ratio: 6.28), and deficient mismatch repair (dMMR) phenotypes (p = 0.044, hazard ratio: 2.62) were independently associated to poor survival of stage I CRC. A high carcinoembryonic antigen level (p = 0.034, hazard ratio: 1.86), rectal cancer (p = 0.035, hazard ratio: 1.81), LVI (p = 0.002, hazard ratio: 3.59) and dMMR phenotypes (p = 0.009, hazard ratio: 2.85) were independently related to short disease-free survival of stage I CRC. CONCLUSIONS: Compared with non-MAC, MAC patients had more T2 patients and more dMMR phenotypes in stage I CRC at presentation, but the mucinous histology is not a significant predictor of recurrence and prognosis in stage I CRC.

The clinical relevance of adjuvant chemotherapy in locally advanced rectal cancer patients achieving near pathological complete response following neoadjuvant chemoradiotherapy: Insights from ypT stage.

BACKGROUND: Near-pathological complete response (Near-pCR) patients constitute a distinct subgroup with limited research attention. The clinical relevance of adjuvant chemotherapy (ACT) in this patient cohort remains uncertain. METHODS: We conducted a retrospective analysis of 245 patients with locally advanced rectal cancer (LARC) who achieved near-pCR following neoadjuvant chemoradiotherapy (NCRT) between 2011 and 2018. Based on their receipt of ACT or not (non-ACT), patients were divided into two groups. We examined their characteristics, treatment modalities, and survival outcomes, particularly focusing on 5-year disease-free survival (DFS) and 5-year overall survival (OS). RESULTS: Among the 245 near-pCR patients, 191 (77.96%) received ACT, and 42 (17.14%) experienced disease recurrence. All 54 (22.04%) Patients in the non-ACT group exhibited a lower 5-year DFS rate (72.2% vs. 85.9%, P = 0.014) and a similar 5-year OS rate (87.0% vs. 91.1%, P = 0.351). Interestingly, those with ypT3-T4 stage tumors demonstrated a worse DFS (76.8% vs. 89.9%, P = 0.010) and OS (87.5% vs. 97.0%, P = 0.004) compared to their counterparts with ypT1-T2 stage tumors. Patients with Non-Downstage tumors showed inferior DFS (76.9% vs. 88.3%, P = 0.025) and OS (87.2% vs. 93.0%, P = 0.166) in comparison to patients with Downstage tumors. The ACT subgroup in patients with Downstage demonstrated statistically better 5-year DFS (93.0% vs. 71.4%, P = 0.001) but analogous survival rates for 5-year OS (OS: 94.0% vs. 89.3%, P = 0.402). Pathological T stage 3-4, perineural invasion (PNI) (positive) and ACT were independent factors influencing 5-year DFS in multivariate analysis. Both univariate and multivariate analysis demonstrated a link between serum carcinoembryonic antigen (CEA) before treatment ≥5 ng/ml and shorter 5-year OS. Notably, near-pCR patients with positive lymph nodes experienced notably diminished 5-year DFS in the absence of ACT post-surgery (61.1% vs. 93.2%, P < 0.001). CONCLUSIONS: ACT demonstrated a significant positive impact on the prognosis of select near-pCR patients, particularly those with ypT1-T2 stage tumors and positive lymph nodes. ypT staging may emerge as a valuable criterion for precise post-surgical ACT guidance in near-pCR patients.

Effects of tumour budding on adjuvant chemotherapy in colorectal cancer.

BACKGROUND: High tumour budding has been indicated as a risk factor of poor survival in colorectal cancer. This study aimed to investigate the impact of tumour budding grades and the use of adjuvant chemotherapy on prognosis in patients with colorectal cancer. METHODS: This study included consecutive colorectal cancer patients who underwent radical surgery for primary colorectal adenocarcinoma at The Sixth Hospital of Sun Yat-sen University between 2009 and 2019. Tumour budding was assessed based on the recommendations of the International Tumor Budding Consensus Conference using haematoxylin and eosin (H&E)-stained slides with tumour samples. The primary outcome of interest was to correlate tumour budding with disease-free survival and overall survival; the secondary outcome was investigation of the impact of adjuvant therapy on different tumour budding grades. In addition, a subgroup analysis was performed for the effects of lymphocytic infiltration on adjuvant chemotherapy in patients with Bd3. RESULTS: Of 709 eligible patients, 412 with colorectal cancer were included. According to the International Tumor Budding Consensus Conference, 210 (50.9 per cent), 127 (30.8 per cent) and 75 (18.2 per cent) were classified as low budding (Bd1), intermediate budding (Bd2) and high budding (Bd3) respectively. Patients with Bd1, Bd2 and Bd3 had 5-year disease-free survival rates of 82.9 per cent, 70.1 per cent and 49.3 per cent respectively, and 5-year overall survival rates of 90 per cent, 79.5 per cent and 62.7 per cent respectively (P <0.001). Adjuvant chemotherapy yielded a significant survival benefit in patients with Bd3 (5-year disease-free survival, 65 per cent versus 31.4 per cent, P <0.001; 5-year overall survival, 84.4 per cent versus 63.1 per cent, P <0.001), but not in those with Bd1 or Bd2. In patients with Bd3, the benefit of adjuvant chemotherapy was maintained in those with low, but not high lymphocytic infiltration. CONCLUSION: High grade of tumour budding was strongly correlated with poorer survival outcomes in colorectal cancer. Patients with Bd3 benefited from adjuvant chemotherapy, with the exclusion of patients with high lymphocytic infiltration.

Mutant KRAS-activated circATXN7 fosters tumor immunoescape by sensitizing tumor-specific T cells to activation-induced cell death.

Mutant KRAS (KRASMUT) is often exploited by cancers to shape tumor immunity, but the underlying mechanisms are not fully understood. Here we report that tumor-specific cytotoxic T lymphocytes (CTLs) from KRASMUT cancers are sensitive to activation-induced cell death (AICD). circATXN7, an NF-κB-interacting circular RNA, governs T cell sensitivity to AICD by inactivating NF-κB. Mechanistically, histone lactylation derived from KRASMUT tumor cell-produced lactic acid directly activates transcription of circATXN7, which binds to NF-κB p65 subunit and masks the p65 nuclear localization signal motif, thereby sequestering it in the cytoplasm. Clinically, circATXN7 upregulation in tumor-specific CTLs correlates with adverse clinical outcomes and immunotherapeutic resistance. Genetic ablation of circAtxn7 in CD8+ T cells leads to mutant-selective tumor inhibition, while also increases anti-PD1 efficacy in multiple tumor models in female mice. Furthermore, targeting circATXN7 in adoptively transferred tumor-reactive CTLs improves their antitumor activities. These findings provide insight into how lymphocyte-expressed circRNAs contribute to T-cell fate decisions and anticancer immunotherapies.

Clinical significance of neoadjuvant chemotherapy for locally advanced colorectal cancer patients with deficient mismatch repair: possibly residual value in the era of immunotherapy.

Background: Deficient mismatch repair (dMMR) or microsatellite instability is one of the well-established molecular biomarkers in colorectal cancer (CRC). The efficiency of neoadjuvant chemotherapy (NAC) in locally advanced colorectal cancer (LACC) patients with dMMR is unclear. Objectives: We assessed the tumor response and clinical outcome in LACC patients with dMMR received NAC. Design: Retrospective, single-center analysis. Methods: From 2013 to 2018, a total of 577 LACC patients with dMMR who underwent radical surgery were identified. Among them, 109 patients who received adjuvant chemotherapy were further screened out for analysis. According to whether receiving NAC or not, 109 patients were divided into two groups with the purpose of retrospectively analyzing their characteristics, treatment, and survival results, especially the 5-year disease-free survival (DFS) and 5-year overall survival. Results: Baseline characteristics were matched between the two groups. One of 40 patients in NAC group recurred, while 13 of 69 patients in non-NAC group recurred. Univariate and multivariate analyses showed that NAC (hazard ratio: 0.115; 95% confidence interval: 0.015-0.897; p = 0.039) was independent influence factor for DFS. In NAC group, there were 13/40 (32.5%) patients for tumor regression grade 1 and 27/40 (67.5%) patients converted clinical positive N-stage into negative N-stage. Conclusion: In this study, NAC was associated with better tumor downstaging and longer 5-year DFS in LACC patients with dMMR. Consequently, NAC might be an additional treatment choice when it comes to such patients in the future.

Clinical significance of adjuvant chemotherapy for pathological complete response rectal cancer patients with acellular mucin pools after neoadjuvant chemoradiotherapy.

Background: Approximately 15-30% of locally advanced rectal cancer (LARC) patients achieved pathological complete response (pCR) after neoadjuvant chemoradiotherapy (CRT) and total mesorectal excision, but the clinical significance of adjuvant chemotherapy (ACT) for pCR patients remains unclear. Objectives: To determine whether LARC pCR patients can benefit from the administration of ACT. Design: Single center retrospective study. Methods: This study retrospectively included 280 LARC patients who achieved pCR after CRT and surgery from 2011 to 2019. The information of patients was recorded. Main outcome measures included 5-year disease-free survival (DFS) and 5-year overall survival. Subgroup analysis was conducted on whether pCR patients with acellular mucin pools received ACT or not. Results: A total of 74/280 (26.4%) patients were identified with acellular mucin pools. Disease recurrence occurred in 38/280 (13.6%) patients, and in the subgroup of patients with acellular mucin pools, 15/74 (20.3%) patients developed distant metastases. The existence of acellular mucin pools was associated with worse DFS (79.7% versus 88.8%, P = 0.037). Among pCR patients with acellular mucin pools, 9/25 (36.0%) of non-ACT patients occurred recurrence, and ACT was beneficial for improving DFS (hazard ratio: 0.245; 95% confidence interval: 0.084-0.719; P = 0.010). Conclusions: The existence of acellular mucin pools may represent a sign of invasive tumor biology, which indicated a negative prognosis. ACT can improve the prognosis of patient with acellular mucin pools, so ACT should be considered for them.

The Deepest Extent of Acellular Mucin Pools in Resected Locally Advanced Rectal Cancer With Pathological Complete Response After Preoperative Chemoradiotherapy: A Hidden Killer?

For patients with locally advanced rectal cancer (LARC) with pathological complete response (pCR), the clinical significance of the distribution extent of acellular mucin pools (AMP) distribution remains unclear, so this study was conducted to address key unanswered questions. We performed a retrospective analysis of 317 patients with LARC with pCR after preoperative chemoradiotherapy and total mesorectal resection from January 2011 to June 2020. Based on AMP existence and the deepest tissue layer of distribution, patients were assigned new stages. The patient information was recorded, and the main outcome measures included 5-year disease-free survival (DFS) and 5-year overall survival (OS). A total of 83/317 (26.2%) patients exhibited AMP, and disease recurrence occurred in 46/317 (14.5%) patients. Over the 5-year median follow-up period, the patients with AMP showed 5-year DFS rates (75.9% vs. 88.9%, P =0.004) and 5-year OS rates (85.5% vs. 95.7%, P =0.002) statistically lower than those of patients without AMP. Disease recurrence was seen in 15/54 (27.8%) patients with AMP within the subserosa and/or the serosa, or adipose tissue. Univariate and multivariate analysis showed that the existence of AMP within the subserosa and/or the serosa, or adipose tissue was an independent risk factor for DFS [hazard ratio (HR): 2.344; 95% confidence interval (CI): 1.256-4.376; P =0.007] and OS [HR: 3.374; 95% CI: 1.438-7.917; P =0.005]. The new stages based on the deepest extent of AMP were related to worse DFS ( P =0.004) and OS ( P =0.003) rates among patients with pCR. In conclusion, the presence of AMP might reduce the prognosis of LARC patients with pCR after chemoradiotherapy, especially in patients with AMP in deeper tissue layers. Therefore, the influence of the deepest AMP extent might be worth considering in staging. Moreover, the revised staging of patients with pCR according to the deepest extent of AMP, which is unrelated to the clinical T stage, might facilitate postoperative management.

Directed natural evolution generates a next-generation oncolytic virus with a high potency and safety profile.

Oncolytic viruses (OVs) represent a type of encouraging multi-mechanistic drug for the treatment of cancer. However, attenuation of virulence, which is generally required for the development of OVs based on pathogenic viral backbones, is frequently accompanied by a compromised killing effect on tumor cells. By exploiting the property of viruses to evolve and adapt in cancer cells, we perform directed natural evolution on refractory colorectal cancer cell HCT-116 and generate a next-generation oncolytic virus M1 (NGOVM) with an increase in the oncolytic effect of up to 9690-fold. The NGOVM has a broader antitumor spectrum and a more robust oncolytic effect in a range of solid tumors. Mechanistically, two critical mutations are identified in the E2 and nsP3 genes, which accelerate the entry of M1 virus by increasing its binding to the Mxra8 receptor and antagonize antiviral responses by inhibiting the activation of PKR and STAT1 in tumor cells, respectively. Importantly, the NGOVM is well tolerated in both rodents and nonhuman primates. This study implies that directed natural evolution is a generalizable approach for developing next-generation OVs with an expanded scope of application and high safety.

Management of Clinically Involved Lateral Lymph Node Metastasis in Locally Advanced Rectal Cancer: A Radiation Dose Escalation Study.

BACKGROUND: Patients with lateral lymph nodes (LLNs) metastasis are not effectively treated with neoadjuvant chemoradiotherapy. This study aimed to compare the efficacy of three neoadjuvant therapeutic regimens, namely, chemotherapy, chemoradiotherapy, and chemoradiotherapy with a dose boost of LLNs, and to identify the optimal approach for treating LLNs metastasis of locally advanced rectal cancer. METHODS: A total of 202 patients with baseline LLNs metastasis (short axis ≥5 mm) and treated with neoadjuvant treatment, followed by radical surgery from 2011 to 2019, were enrolled. The short axis of the LLNs on baseline and restaging MRI were recorded. Survival outcomes were compared. RESULTS: In the booster subgroup, shrinkage of LLNs was significantly greater than in the neoadjuvant chemotherapy and chemoradiotherapy subgroups (P <0.001), without increasing radiation related side effects (P = 0.121). For patients with baseline LLNs of short axis ≥5 mm in the booster subgroup, the response rate (short axis <5 mm on restaging MRI) was 72.9%, significantly higher than patients in the neoadjuvant chemotherapy subgroup (48.9%, P = 0.007) and higher than for patients in the neoadjuvant chemoradiotherapy group (65.0%), but there was no statistical difference (P = 0.411). The 3-year local recurrence and lateral local recurrence rates were both 2.3% in the dose booster group, which were lower than those of the other two subgroups (local recurrence: P <0.001; lateral local recurrence: P <0.001). The short axis of lateral lymph nodes (≥5 and <5 mm) on restaging MRI was an independent risk factor for prognosis (P <0.05). CONCLUSION: Radiation dose boost is an effective way of increasing the response rate and decreasing recurrence rates. The restaging LLNs with short axis ≥5 mm is a predictor of poor prognosis.

Systemic inflammatory indices predict tumor response to neoadjuvant chemoradiotherapy for locally advanced rectal cancer.

Systemic inflammatory responses are associated with the prognosis of patients with colorectal cancer. However, the value in predicting tumor responses to neoadjuvant chemoradiotherapy (nCRT) remains to be elucidated. The current study aimed to investigate the association between systemic inflammatory indices and pathological complete response (pCR). The training and validation cohorts included 225 and 96 patients with locally advanced rectal cancer. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio were recorded prior to nCRT and radical surgery. Univariate and multivariate analysis were used to investigate the association between systemic inflammatory indices and pCR. Systemic inflammatory indices prior to or following treatment had no significant association with pCR; however, the percentage change in NLR from pre-nCRT to post-nCRT was associated with a poor response, and a percentage change of >21.5% NLR (P=0.006; OR=0.413; 95% CI=0.22-0.773) was a predictor of poor pCR. Therefore, in rectal cancer, the percentage change in NLR from pre- to post-nCRT was found to be a predictor of poor pCR.

Quantitative CT measurement of left colonic and pelvic mesenteric adipose volume in radiation proctitis.

BACKGROUND: The edema of left colonic and pelvic mesenteric adipose tissues has long been recognized in surgery as a characteristic feature of radiation proctitis (RP). However, the correlation between mesenteric adipose volume and RP has not been extensively clarified. The purpose of this study was thus to assess the variation of left colonic and pelvic mesenteric adipose volume in RP. METHODS: From March 2013 to June 2015, the data of 52 patients with locally advanced rectal cancer who underwent neoadjuvant chemoradiotherapy, including 23 patients with RP and 29 with non-RP (nRP), were retrieved. The mesenteric adipose volume was quantified via a computed tomography (CT) reconstruction method. Corresponding analyses were conducted to observe the correlation between the relative change of mesenteric adipose volume and the thickening degree of the rectal wall. RESULTS: The baseline data of the RP group and the nRP group were comparable. There was no significant difference in the relative change of the left colonic mesenteric adipose volume in each vertebral space from the third lumbar vertebra to the first sacral vertebra before and after radiotherapy. The relative change of pelvic mesenteric adipose volume (ΔVp%) was notably higher in the RP group compared to the nRP group. With a ΔVp% cutoff value of 3.67%, the sensitivity and specificity for the diagnosis of RP were 65.2% and 86.2%, respectively. According to the correlation analysis, ΔVp% in the RP group was significantly correlated with the thickening degree of the rectal wall after radiotherapy (r=0.47, P=0.024). CONCLUSIONS: The increment of the relative change of pelvic mesenteric adipose volume quantitatively measured by CT can be clinically useful in identifying RP.

Efficacy and complications of argon plasma coagulation for hemorrhagic chronic radiation proctitis.

BACKGROUND: Chronic radiation proctitis (CRP) is a complication which occurs in 1%-5% of patients who undergo radiotherapy for pelvic malignancies. Although a wide range of therapeutic modalities are available, there is no literature to date showing any particularly appropriate therapeutic modality for each disease stage. Argon plasma coagulation (APC) is currently recommended as the first-choice treatment for hemorrhagic CRP, however, its indication based on long-term follow-up is still unclear. On the hypothesis that the long-term efficacy and safety of APC are not fully understood, we reviewed APC treatment for patients with hemorrhagic CRP from a single center. AIM: To assess the long-term efficacy and safety of APC for hemorrhagic CRP. METHODS: This is a retrospective study of consecutive patients treated with APC for hemorrhagic CRP from January 2013 to October 2017. Demographics, clinical variables, and typical endoscopic features were recorded independently. Success was defined as either cessation of bleeding or only occasional traces of bloody stools with no further treatments for at least 12 mo after the last APC treatment. We performed univariate and multivariate analyses to identify factors associated with success and risk factors for fistulas. RESULTS: Forty-five patients with a median follow-up period of 24 mo (range: 12-67 mo) were enrolled. Fifteen (33.3%) patients required blood transfusion before APC. Successful treatment with APC was achieved in 31 (68.9%) patients. The mean number of APC sessions was 1.3 (1-3). Multivariate analysis showed that APC failure was independently associated with telangiectasias present on more than 50% of the surface area [odds ratio (OR) = 6.53, 95% confidence interval (CI): 1.09-39.19, P = 0.04] and ulcerated area greater than 1 cm2 (OR = 8.15, 95%CI: 1.63-40.88, P = 0.01). Six (13.3%) patients had severe complications involving rectal fistulation. The only factor significantly associated with severe complications was ulcerated area greater than 1 cm2 (P = 0.035). CONCLUSION: The long-term efficacy of APC for hemorrhagic CRP is uncertain in patients with telangiectasias present on > 50% of the surface area and ulceration > 1 cm2.