Defecation disorder and anal function after surgery for lower rectal cancer in elderly patients.

AIM: This study aims to investigate the association of patient age with defecation disorders and anal function after lower rectal cancer surgery. METHODS: We retrospectively reviewed the data of 141 consecutive patients with lower rectal cancer who underwent sphincter-preserving operation. The patients were classified into five categories by age thresholds at 65, 70, 75, 80, and 85 years, for disaggregate analysis. Anal manometry was used for measuring the maximum resting pressure, high-pressure zone, and maximum squeeze pressure. Anal manometry was performed preoperatively and at 3, 6, 9, and 12 months postoperatively. The Wexner and low anterior resection syndrome scores were assessed at 1, 3, 6, 9, and 12 months after rectal surgery or stoma closure for patients with ileostomy. RESULTS: The data of 117 patients were reviewed. No significant differences were found between the younger and elderly groups in any characteristics across the six age groups. The preoperative intra-anal pressures of the elderly patients were slightly lower than those of the younger patients; however, there was no significant difference in the course of postoperative intra-anal pressures. Defecation disorder, as measured by the Wexner and low anterior resection syndrome scores, improved significantly in elderly patients compared to younger patients. CONCLUSION: There was no significant difference in the course of postoperative intra-anal pressures between the elderly and younger patients. However, defecation disorders in elderly patients significantly improved compared with younger patients. Sphincter-preserving operation can be a viable treatment option for active elderly patients.

Clinical Utility and Characteristics of the LARS Score Compared to the CCIS.

PURPOSE: The low anterior resection syndrome (LARS) score (LS) has been widely validated and has become an international tool for evaluating postoperative bowel dysfunction. However, many physicians still use the conventional incontinence scores in LARS treatment. Moreover, interpretation of LS and its relationship with conventional incontinence scores are not yet well understood. Here we compared the LS with the Cleveland Clinic Incontinence Score (CCIS) to clarify the clinical utility and characteristics of the LARS score. METHODS: We performed a multicentre observational study, recruiting 246 rectal cancer patients following sphincter-preserving surgery. Patients completed the LS, CCIS, and SF36 questionnaires. RESULTS: The response rate was 76.4%, and a total of 180 patients were analysed. The LS was strongly correlated with the CCIS (P < 0.001, rs = 0.727). However, among 116 patients determined to not have incontinence (CCIS 0-5), 51 (44%) were diagnosed with LARS (29 with minor LARS and 22 with major LARS). Among 68 patients without LARS, only 3 were diagnosed as having incontinence (CCIS > 6). In comparison with background factors, aging and elapsed time were associated with only LS. High LS and CCIS both showed significant quality-of-life impairment as assessed by the SF-36. CONCLUSION: This is the first study to determine the difference in the numeric values between the CCIS and LS. The LS can be a convenient tool for LARS screening, identifying a wide range of patients with LARS, including those with incontinence evaluated by CCIS. Assessment using the CCIS may often underestimate LARS.

Short-Term Outcomes with Standardized Transperineal Minimally Invasive Abdominoperineal Excision for Rectal Cancer.

BACKGROUND: Transperineal abdominoperineal excision (TpAPE) is an emerging approach for low rectal cancers but is technically challenging. Based on an anatomical study we conducted previously, we have standardized the TpAPE procedure. Here, we aimed to validate the feasibility of the standardized TpAPE by investigating the short-term outcomes. METHODS: From January 2018 to November 2020, a total of 405 patients underwent laparoscopic or robotic rectal resection for rectal cancer in our institution. For the current study, we analyzed data for the 31 patients who underwent TpAPE. The abdominal phase was performed synchronously with the perineal phase using either a laparoscopic or robotic approach. Short-term outcomes included operative and pathological results. RESULTS: Of the 31 cases, we identified anterior quadrant tumor invasion in 21. Most of the cases were advanced, with 6 staged as cT3 and 20 as T4. Of the 27 cases not involving distant metastasis, neoadjuvant therapy was performed in 19. No inadvertent rectal perforation or urethral injury was found intraoperatively. The median procedural duration to specimen removal was 250 min (interquartile range, 204-287), and the median intraoperative blood loss was 10 ml (interquartile range, 5-40). Regarding postoperative complications, perineal wound infection developed in 11 cases. A positive circumferential resection margin was found in 3, corresponding to the positive rate of 9.7%. These three cases were among the first 12 cases involving standardized TpAPE. CONCLUSIONS: The current results indicate that TpAPE can be performed safely and might represent a useful option for low rectal cancer resection.

A modified method for resected specimen processing in rectal cancer: Semi-opened with transverse slicing for measuring of the circumferential resection margin.

Circumferential resection margin (CRM) is essential for oncological quality assessment in rectal cancer surgery. CRM represents a surrogate parameter for oncological outcomes and is important for stratifying treatment strategies in Western nations. In Japan, the mesentery is removed for specimen processing in order to extract as many lymph nodes (LNs) as possible; consequently, CRM cannot be measured. Given the diversification of treatment strategies for rectal cancer, the lack of measurement of CRM to assess surgical outcomes is a crucial issue that must be resolved. Therefore, it is necessary to establish a method enabling measurement of CRM while enjoying the advantages of the Japanese method. In the method we developed, the mesentery is removed from the rectum more than 2 cm away from the tumor, and the vicinity of the tumor is circularized. It is necessary to investigate the usefulness of this method prospectively in a multi-center study.

Snapshots of lymphatic pathways in colorectal cancer surgery using near-infrared fluorescence, in vivo and ex vivo.

INTRODUCTION: Indocyanine green (ICG) fluorescence imaging has been used for blood flow assessment in anastomoses in the field of colorectal cancer surgery. However, whether ICG fluorescence is related to the presence of cancer cells in the lymph nodes is unclear. We explored the utilization of ICG fluorescence in colorectal cancer surgery. MATERIALS AND METHODS: ICG was injected into the submucosa around the tumor before radical resection in colorectal cancer patients. Intraoperatively, near-infrared (NIR) fluorescence was used for lymphatic flow visualization. After specimen removal, harvested lymph nodes were classified as positive or negative based on the detection of fluorescence, followed by pathological examination. ICG distribution on a section of each lymph node was examined by fluorescence microscopy. RESULTS: Overall, 155 patients underwent real-time NIR fluorescence imaging-guided surgery. Altogether, 1,017 lymph nodes were retrieved from these patients. Metastatic lymph nodes were present in 36 (5.8%) of 622 fluorescence-negative lymph nodes, which was significantly higher than 11 (2.8%) of 395 fluorescence-positive lymph nodes (odds ratio: 2.15, P = 0.03). Fluorescence microscopy of metastatic lymph nodes showed that ICG fluorescence was present in the normal structural region but not in the cancerous region of the lymph nodes. Furthermore, ICG fluorescence was observed in all metastatic lymph nodes, except those with cancer cells occupying >90% of the total area. CONCLUSIONS: ICG fluorescence detected only the normal parts of the lymph node draining from the peritumoral area and not the cancer tissues. This finding is important for developing appropriate strategies for navigation surgery using NIR fluorescence.

Laparoscopic low anterior resection for rectal cancer wherein the inferior mesenteric artery arose from the superior mesenteric artery: a case report.

BACKGROUND: Few cases have been reported of colorectal cancer with inferior mesenteric artery (IMA) branching abnormalities; therefore, the lymphatic flow in such cases remains unknown. We report the first case of locally advanced rectal cancer in which the IMA arose from the superior mesenteric artery (SMA) in which we achieved to visualize the lymphatic flow. CASE PRESENTATION: A 65-year-old woman complaining of bloody stools was investigated in our hospital and suspected with rectal cancer. Colonoscopy and abdominal enhanced computed tomography (CT) revealed a circumscribed, localized ulcerative tumor in the rectum. 3-Dimensional contrast-enhanced computed tomography (3D-CT) showed that the IMA arose from the SMA. The patient was diagnosed with rectal cancer (cT3N0M0, cStage IIa) and laparoscopic low anterior resection was performed. The sigmoid colon was resected using the medial approach. Only the plexus of the colic branch of the lumbar splanchnic nerve was observed at the site where the root of the IMA usually exists and showed interruption of the indocyanine green (ICG) fluorescence-illuminated lymphatics. The root of the IMA was ligated, and Japanese D3 lymphadenectomy was performed, preserving the accessory middle colic artery. All fluorescent lymph nodes were resected. The pathological diagnosis was pT4aN1aM0 stage IIIb. The patient's postoperative course was uneventful. Adjuvant chemotherapy was administered, and the patient was recurrence-free at 1.5 years after surgery. CONCLUSIONS: We were able to perform safe and appropriate surgery oncologically, despite abnormal vascular anatomy, due to preoperative identification using 3D-CT and intraoperative navigation using ICG administration.

MRI-detected extramural vascular invasion potentiates the risk for pathological metastasis to the lateral lymph nodes in rectal cancer.

PURPOSE: Multidisciplinary treatment for locally advanced rectal cancer requires an accurate assessment of the risk of metastasis to the lateral lymph nodes (LNs). We herein aimed to stratify the risk of pathological metastasis to lateral LNs based on the preoperatively detected malignant features. METHODS: All patients with rectal cancer who underwent surgery from January 2016 to July 2020 were identified. We recorded the TNM factors; perirectal and lateral LN sizes; and MRI findings, including mesorectal fascia involvement, extramural vascular invasion (EMVI), tumor site, and tumor distance from the anal verge. RESULTS: 101 patients underwent rectal resection with lateral lymph node dissection, of whom 16 (15.8%) exhibited pathological metastases to the lateral LNs. Univariate analyses demonstrated that lateral LN metastasis was significantly correlated with mrEMVI positivity (p = 0.0023) and a baseline lateral LN short-axis length of ≥ 5 mm (p < 0.0001). These significant associations were confirmed by a multivariate analysis (p = 0.0254 and 0.0027, respectively). The lateral LN metastasis rate was as high as 44% in cases bearing both risk factors, compared to 0% in cases lacking both risk factors. CONCLUSION: The results elucidated in this study may contribute to risk stratification, which can be used when determining the indications for lateral lymph node dissection.

Transperineal minimally invasive abdominoperineal excision for rectal cancer based on anatomical analysis of the muscular structure.

INTRODUCTION: Transperineal minimally invasive abdominoperineal excision (TpAPE) may help minimize surgical invasiveness and make it possible to perform two-team surgery, although this procedure is regarded as difficult. The anatomical structures are complicated and have not been clearly defined, particularly on the anterior side of the anorectal junction in men. We investigated the anatomical configuration around the anterior wall of the anorectal junction, focusing on the structure of the striated muscles, to establish a standard procedure for TpAPE. METHODS: We scrutinized the T2 -weighted MRI scans of 106 men, and two male cadavers were used to examine the muscular structure surrounding the anorectal junction. We established our standardized procedure for TpAPE based on these anatomical studies. We also analyzed the clinicopathological findings from five men who had undergone TpAPE at our institution. RESULTS: Using MRI, we detected band-like muscles bilaterally, just medial to the puborectal muscle in all analyzed patients, which we termed the rectal anterolateral muscle. We also detected the muscles that may correspond to the rectal anterolateral muscle when inspecting the cadavers. The standardized TpAPE procedures were carried out uneventfully for the five cases, and intraoperative complications such as urethral injury and inadvertent rectal perforation did not occur. CONCLUSION: We standardized the TpAPE procedure based on anatomical examination of the muscular structure around the anal canal. The findings can contribute to safe implementation of TpAPE.

Timing of indocyanine green injection prior to laparoscopic colorectal surgery for tumor localization: a prospective case series.

BACKGROUND: Accurate identification of tumor sites during laparoscopic colorectal surgery helps to optimize oncological clearance. We aimed to assess the timing of the local injection preoperatively and clarify the usefulness and limitation of tumor site marking using indocyanine green (ICG) fluorescence imaging. METHODS: Consecutive patients who underwent primary colorectal cancer surgery from September 2017 to January 2019 were included. Preoperatively, lower endoscopy was used to inject the ICG solution into the submucosal layer near the tumor. During laparoscopic surgery, ICG fluorescence marking as the tumor site marking was detected using a laparoscopic near-infrared camera system. The detection rate and factors associated with successful intraoperative ICG fluorescence visualization including the interval between local injection and surgery were evaluated. RESULTS: One hundred sixty-five patients were enrolled. Using the laparoscopic near-infrared system, the intraoperative detection rates of ICG marking were 100% for ICG injection within 6 days preoperatively, 60% for injection between 7 and 9 days preoperatively, and 0% for injection earlier than 10 days preoperatively. There were no complications associated with ICG marking. Additionally, this method did not disturb the progress of the surgical procedure because injected ICG in the submucosal layer did not cause any tissue inflammation, and if ICG spilled into the serosa, it was invisible by white light. CONCLUSION: Advantages of ICG fluorescence tumor site marking were high visibility of infrared imaging during laparoscopic colorectal surgery and minimal adverse events of surgery. One of the most important findings regarding practical use was a rapid decrease in fluorescence marking visibility if one week passed from the time of ICG local injection.

Optimizing antiemetic treatment for chemotherapy-induced nausea and vomiting in Japan: Update summary of the 2015 Japan Society of Clinical Oncology Clinical Practice Guidelines for Antiemesis.

Patients with cancer should appropriately receive antiemetic therapies against chemotherapy-induced nausea and vomiting (CINV). Antiemetic guidelines play an important role in managing CINV. Accordingly, the first Japanese antiemetic guideline published in 2010 by the Japan Society of Clinical Oncology (JSCO) has considerably aided Japanese medical staff in providing antiemetic therapies across chemotherapy clinics. With the yearly advancements in antiemetic therapies, the Japanese antiemetic guidelines require revisions according to published evidence regarding antiemetic management worldwide. A revised version of the first antiemetic guideline that considered several upcoming evidences had been published online in 2014 (version 1.2), in which several updated descriptions were included. The 2015 JSCO clinical practice guideline for antiemesis (version 2.0) (in Japanese) has addressed clinical antiemetic concerns and includes four major revisions regarding (1) changes in emetogenic risk categorization for anti-cancer agents, (2) olanzapine usage as an antiemetic drug, (3) the steroid-sparing method, and (4) adverse drug reactions of antiemetic agents. We herein present an English update summary for the 2015 JSCO clinical practice guideline for antiemesis (version 2.0).

Effect of Rikkunshito, a Traditional Japanese Herbal Medicine, on Delayed Gastric Emptying and Oral Dietary Intake After Pancreaticoduodenectomy: A Prospective, Randomized, Single-Center, Open-Labeled Study.

INTRODUCTION: Delayed gastric emptying (DGE) remains an important problem after pancreaticoduodenectomy (PD). There is a lack of effective treatments for early recovery of oral dietary intake. Rikkunshito (RKT), a Japanese herbal medicine, has been gaining attention as a facilitator of gastric emptying. We evaluated the effects of RKT on DGE after PD. METHODS: In this prospective, randomized, open-labeled study, patients were randomly allocated before PD in a 1:1 ratio to the RKT group or the control group that received no additional treatment. The RKT group received 2.5 g of RKT three times daily (7.5 g/day) from postoperative day (POD) 1 to POD 21. The primary endpoint was the incidence of DGE. Secondary endpoints were short-term postoperative outcomes including oral dietary intake volume and perioperative changes in levels of the hormones ghrelin and leptin. Patients were observed until hospital discharge. RESULTS: Twenty-six patients in each group (n = 52) completed the protocol treatment and were included in the analysis set. There were no statistically significant differences in basic characteristics and operative factors. The overall incidence of DGE was not statistically different between the RKT and control groups (30.8% vs 30.8%, p>0.9999). There were no statistically significant differences in the amount of postoperative oral dietary intake represented by total dietary intake (TDI) up to POD 14 and POD 21, complications, and length of hospital stay. No adverse events related to this study were observed. In the RKT group, total ghrelin and acyl-ghrelin were significantly upregulated and leptin was significantly downregulated earlier than in the control group. CONCLUSION: RKT treatment from POD 1 to 21 did not reduce the incidence of DGE and had no clinically beneficial effect on short-term postoperative outcomes irrespective of changes in hormone levels.

Evaluation of negative-pressure wound therapy for surgical site infections after ileostomy closure in colorectal cancer patients: a prospective multicenter study.

PURPOSE: Surgical site infection (SSI) occurs at a high rate after ileostomy closure. The effect of preventive negative-pressure wound therapy (NPWT) on SSI development in closed wounds remains controversial. We conducted a prospective multicenter study to evaluate the usefulness of preventive NPWT for SSI after ileostomy closure. METHODS: From January 2018 to November 2018, 50 patients who underwent closure of ileostomy created after surgery for colorectal cancer participated in this study. An NPWT device was applied to each wound immediately after surgery and then treatment was continued for 3 days. The primary endpoint was 30-day SSI, and the secondary endpoints were the incidence of seroma, hematoma, and adverse events related to NPWT. RESULTS: No patients developed SSI, seroma, or hematoma. Adverse events that may have been causally linked with NPWT were contact dermatitis in two patients and wound pain in one patient, and there were no cases of discontinuation or decompression of NPWT. CONCLUSION: The use of NPWT following ileostomy closure may be useful for reducing the development of SSI in colorectal cancer patients. This is a prospective multicenter pilot study and we are planning a comparative study based on these successful results. TRAIL REGISTRATION: Registration number: UMIN000032053 ( https://www.umin.ac.jp/ ).

Gastrointestinal stromal tumor of the rectum resected by transanal total mesorectal excision after neoadjuvant imatinib treatment: A case report.

This report describes the combination of a transanal total mesorectal excision (TaTME) and neoadjuvant therapy with Imatinib mesylate (IM) for a gastrointestinal stromal tumor (GIST) of the lower rectum. A 49-year-old man presented with a submucosal tumor with ulcer located 3 cm above the anal verge. Histopathologically, a biopsy showed spindle-shape cells, positive for C-kit and CD34, negative for smooth muscle actin, desmin and S-100 protein. Genetically, this GIST had the mutation in KIT exon 11. IM (400 mg/d) was administered as neoadjuvant therapy for 80 days. The GIST shrank from 4.7 to 3.3 cm in diameter. Abdominal and transanal approach were started at the same time. The tumor was resected by TaTME successfully. The manometric pressure data and anal function were preserved before and after surgery. TaTME and neoadjuvant therapy with IM provide a treatment option which can preserve anal function for the lower rectal GIST.

Upregulation of adipocyte enhancer-binding protein 1 in endothelial cells promotes tumor angiogenesis in colorectal cancer.

Tumor angiogenesis is an important therapeutic target in colorectal cancer (CRC). We aimed to identify novel genes associated with angiogenesis in CRC. Using RNA sequencing analysis in normal and tumor endothelial cells (TECs) isolated from primary CRC tissues, we detected frequent upregulation of adipocyte enhancer-binding protein 1 (AEBP1) in TECs. Immunohistochemical analysis revealed that AEBP1 is upregulated in TECs and stromal cells in CRC tissues. Quantitative RT-PCR analysis showed that there is little or no AEBP1 expression in CRC cell lines, but that AEBP1 is well expressed in vascular endothelial cells. Levels of AEBP1 expression in Human umbilical vein endothelial cells (HUVECs) were upregulated by tumor conditioned medium derived from CRC cells or by direct coculture with CRC cells. Knockdown of AEBP1 suppressed proliferation, migration, and in vitro tube formation by HUVECs. In xenograft experiments, AEBP1 knockdown suppressed tumorigenesis and microvessel formation. Depletion of AEBP1 in HUVECs downregulated a series of genes associated with angiogenesis or endothelial function, including aquaporin 1 (AQP1) and periostin (POSTN), suggesting that AEBP1 might promote angiogenesis through regulation of those genes. These results suggest that upregulation of AEBP1 contributes to tumor angiogenesis in CRC, which makes AEBP1 a potentially useful therapeutic target.

Efficacy of indocyanine green fluorescence angiography in preventing anastomotic leakage after laparoscopic colorectal cancer surgery.

PURPOSE: Some recent studies have suggested that fluorescence angiography with indocyanine green (ICG) might be useful for preventing anastomotic leakage (AL) after laparoscopic colorectal surgery. However, its efficacy has not been proven. We evaluated whether intraoperative ICG fluorescence angiography could decrease the AL rate with laparoscopic colorectal cancer surgery. METHODS: This retrospective study included patients with colorectal cancer who underwent laparoscopic surgery at our institution between March 2014 and December 2018. Patients were divided into two groups: with or without ICG fluorescence angiography. The primary outcome was the rate of AL. RESULTS: A total of 488 patients were included: 223 patients in the ICG group and 265 patients in the no-ICG group. In the ICG group, the transection line was changed to a more proximal location in seven patients (3.1%), including one patient with transverse colon surgery and six with rectal surgery. None of these seven patients developed AL. There were 18 ALs (3.7%) overall. The AL rate was 1.8% in the ICG group and 5.3% in the no-ICG group. For colon cancer, there were no significant differences in the AL rate between the groups (p = 0.278). In rectal cancer, the AL rate was significantly lower in the ICG group than in the no-ICG group (3.5% vs. 10.5%, p = 0.041). After propensity score matching, the AL rate was also significantly lower in the ICG group for rectal cancer (p = 0.044). CONCLUSION: ICG fluorescence angiography can potentially reduce the AL rate with laparoscopic rectal cancer surgery.

Current status of site-specific cancer registry system for the clinical researches: aiming for future contribution by the assessment of present medical care.

BACKGROUND: The current status of site-specific cancer registry has not been elucidated, but sufficient system is found in some societies. The purpose of this study was to clear the present condition of site-specific cancer registries in Japan and to suggest for the improvement. METHODS: The questionnaire was conducted by the study group of the Ministry of Health, Labor, and Welfare. It consisted of 38 questions, conflicts of interest, clinical research method, informed consent and funding for registry. We distributed this questionnaire to 28 academic societies, which had published the clinical practice guideline(s) assessed under Medical Information Network Distribution Service (MINDS). RESULTS: The concept of the importance in assessment for medical quality by the data of the site-specific cancer registry was in good consensus. But the number of the society with the mature registry was limited. The whole-year registry with the scientific researches in the National Clinical Database (NCD) and in the Translational Research Informatics Center (TRI) might seem to be in success, because assured enhancement may be estimated. Now, academic societies have the structural factors, i.e., the financial limitation in the registry maintenance and the data analysis, and in the difficulty of employment of the researchers with skill and talent. CONCLUSIONS: To manage the site-specific cancer registry effectively, the scientific registry system will be essentially important. Each academic society had much experienced highly qualified clinical researches in past. Accordingly, the scientific suggestion and co-operation should be of great importance for the improvement.

Validation of the Japanese Version of the Low Anterior Resection Syndrome Score.

BACKGROUND: The low anterior resection syndrome (LARS) score is a patient-reported outcome measure to evaluate the severity of bowel dysfunction after rectal cancer surgery by scoring the major symptoms of LARS. The aim of this study was to translate the English version of the LARS score into Japanese and to investigate the validity and reliability of the LARS score. METHODS: The LARS score was translated in Japanese following current international recommendations. A total of 149 rectal cancer patients completed the LARS score questionnaire and were also asked a single question assessing the impact of bowel function on quality of life (QoL). A total of 136 patients answered the LARS score questionnaire twice. RESULTS: The Japanese LARS score showed high convergent validity, based on its good correlation between the LARS score and QoL (p < 0.001). The LARS score was able to discriminate between patients according to the tumor distance to anal verge (p < 0.001), type of surgery (p < 0.001), and time since surgery (p = 0.001). Patients after ultra-low anterior resection and intersphincteric resection showed especially high scores. The score also had high test-retest reliability (intraclass correlation coefficient: 0.87). CONCLUSION: The Japanese LARS score is a valid and reliable tool for measuring LARS. The LARS score is appropriate for assessments in postoperative bowel function and international comparison. Using this score, patient-reported outcome measures of LARS in Japanese patients can be shared internationally. Additional validation reports from non-English speaking countries can support the LARS score as a worldwide assessment tool for postoperative bowel dysfunction.

LY6/PLAUR domain containing 3 has a role in the maintenance of colorectal cancer stem-like cells.

Colorectal carcinoma (CRC) is one of the most frequently diagnosed cancers and the leading cause of cancer-related death for both men and women. Recent studies have revealed that a small sub-population of cancer cells, termed cancer stem-like cells (CSCs)/cancer-initiating cells (CICs), are endowed with tumor-initiating ability, self-renewal ability and differentiation ability. CSCs/CICs are resistant to current therapies including chemotherapy and radiotherapy. Thus, CSCs/CICs are responsible for recurrence and metastasis, and eradication of CSCs/CICs is essential to cure cancer. In this study, we isolated CR-CSCs/CICs as sphere-cultured cells and found that a product derived from LY6/PLAUR domain containing 3 (LYPD3) is preferentially expressed in CSCs/CICs. Gene overexpression and gene knockdown experiments revealed that LYPD3 has a role in the maintenance of CR-CSCs/CICs. The findings provide a novel molecular insight into CR-CSCs/CICs.

Identification and functional analysis of variants of a cancer/testis antigen LEMD1 in colorectal cancer stem-like cells.

Colorectal cancer (CRC) is one of the most common malignancy, and the prognosis is not still satisfactory due to treatment resistance, recurrence and distant metastasis. Cancer stem cells (CSCs)/cancer-initiating cells (CICs) is endowed with higher tumor-initiating ability, self-renewal ability and differentiation ability, and CSCs/CICs are resistant to treatments. Thus, CSCs/CICs are thought to be responsible for recurrence and distant metastasis, and eradication of CSCs/CICs is essential to cure CRCs. However, the molecular mechanisms of CSCs/CICs are remain unknown, and we aimed to elucidate molecular aspects of CR-CSCs/CICs in this study. We screened the transcriptome data of primary human CR-CSCs/CICs that we previously established, and found that LEM domain containing 1 (LEMD1) is preferentially expressed in CR-CSCs/CICs. LEMD1 belongs to cancer-testis (CT) antigen, and has five transcript variants (variant 1 [V1] - variant 5 [V5]). We found that LEMD1 V1, V2 and V3 is expressed in testis and CR-CSCs/CICs, whereas LEMD1 V4 and V5 is ubiquitously expressed. LEMD1 gene knockdown experiments using siRNAs and gene overexpression experiments revealed that LEMD1 has a role in the maintenance of CR-CSCs/CICs. These observations indicate that CR-CSC/CIC-specific LEMD1 variants are reasonable target of CR-CSC/CIC-targeted therapy.

ST6GALNAC1 plays important roles in enhancing cancer stem phenotypes of colorectal cancer via the Akt pathway.

Colorectal cancer (CRC) is a mortal disease due to treatment resistance, recurrence and distant metastasis. Emerging evidence has revealed that a small sub-population of cancer cells termed cancer stem cells (CSCs)/ cancer-initiating cells (CICs) is endowed with high levels of tumor-initiating ability, self-renewal ability and differentiation ability and is responsible for treatment resistance, recurrence and distant metastasis. Eradication of CSCs/CICs is essential to improve current treatments. However, the molecular mechanisms by which CSCs/CICs are maintained are still elusive. In this study, we aimed to determine the molecular mechanisms by which colorectal (CR)-CSCs/CICs in are maintained human primary CRC cells. CR-CSCs/CICs were isolated by sphere-culture and the ALDEFLUOR assay, and transcriptome analysis revealed that the gene ST6 N-Acetylgalactosaminide Alpha-2,6-Sialyltransferase 1 (ST6GALNAC1) was expressed at high levels in CR-CSCs/CICs. Overexpression of ST6GALNAC1 enhanced the expression of sialyl-Tn (STn) antigen, which is carried by the CSC marker CD44, and increased the sphere-forming ability and resistance to a chemotherapeutic reagent. The opposite phenomena were observed by gene knockdown using siRNA. Furthermore, the Akt pathway was activated in ST6GANAC1-overexpressed cells, and activation of the pathway was cancelled by gene knockdown of galectin-3. The results indicate that ST6GALNAC1 has a role in the maintenance of CR-CSCs/CICs by activating the Akt pathway in cooperation with galectin-3 and that ST6GalNAC1 (or STn antigen) might be a reasonable molecule for CSC/CIC-targeting therapy.