Vasorin (VASN) overexpression promotes pulmonary metastasis and resistance to adjuvant chemotherapy in patients with locally advanced rectal cancer.

BACKGROUND: LARC patients commonly receive adjuvant therapy, however, hidden micrometastases still limit the improvement of OS. This study aims to investigate the impact of VASN in rectal cancer with pulmonary metastasis and understand the underlying molecular mechanisms to guide adjuvant chemotherapy selection. METHODS: Sequencing data from rectal cancer patients with pulmonary metastasis from Sun Yat-sen University Cancer Center (SYSUCC) and publicly available data were meticulously analyzed. The functional role of VASN in pulmonary metastasis was validated in vivo and in vitro. Coimmunoprecipitation (co-IP), immunofluorescence, and rescue experiments were conducted to unravel potential molecular mechanisms of VASN. Moreover, VASN expression levels in tumor samples were examined and analyzed for their correlations with pulmonary metastasis status, tumor stage, adjuvant chemotherapy benefit, and survival outcome. RESULTS: Our study revealed a significant association between high VASN expression and pulmonary metastasis in LARC patients. Experiments in vitro and in vivo demonstrated that VASN could promote the cell proliferation, metastasis, and drug resistance of colorectal cancer. Mechanistically, VASN interacts with the NOTCH1 protein, leading to concurrent activation of the NOTCH and MAPK pathways. Clinically, pulmonary metastasis and advanced tumor stage were observed in 90% of VASN-positive patients and 53.5% of VASN-high patients, respectively, and VASN-high patients had a lower five-year survival rate than VASN-low patients (26.7% vs. 83.7%). Moreover, the Cox analysis and OS analysis indicated that VASN was an independent prognostic factor for OS (HR = 7.4, P value < 0.001) and a predictor of adjuvant therapy efficacy in rectal cancer. CONCLUSIONS: Our study highlights the role of VASN in decreasing drug sensitivity and activating the NOTCH and MAPK pathways, which leads to tumorigenesis and pulmonary metastasis. Both experimental and clinical data support that rectal cancer patients with VASN overexpression detected in biopsies have a higher risk of pulmonary metastasis and adjuvant chemotherapy resistance.

[Intervention effect of biofeedback combined with pelvic floor muscle exercise on low anterior resection syndrome in patients with low anus-preserving rectal cancer].

Objective: To explore the effect of biofeedback training combined with pelvic floor muscle exercise on the recovery of anorectal function in patients with middle and low rectal cancer undergoing sphincter-preserving surgery, and to find the best way to prevent low anterior resection syndrome. Methods: A single-center prospective randomized controlled study was conducted. One hundred and nine patients with mid-low rectal cancer in Sun Yat-sen University Cancer Centre from June 2015 to December 2016 were enrolled in the study, who were going to undergo sphincter-preserving surgery or preventive ostomy after preoperative chemoradiotherapy. They were divided into three groups: blank control group, pelvic floor muscle exercise group and biofeedback training combined with pelvic floor muscle exercise group. Intervention and follow-up were conducted for 16 months. High-resolution anorectal manometry was used to measure the objective anorectal pressure and sensory index of patients, and the Chinese version of MSKCC Intestinal Function Questionnaire was used to evaluate the intestinal function of patients. The differences of objective anorectal manometry index and subjective intestinal function between the three groups were compared, and the occurrence of low anterior rectal resection syndrome was evaluated. Results: At the end of the intervention, the total scores of anal resting pressure, rectal resting pressure, anal maximum systolic pressure, anal maximum systolic time, initial rectal volume, rectal fecal sensory capacity, rectal maximum tolerance capacity, rectal compliance, anorectal hypertensive zone and total score of intestinal function in the biofeedback training combined with pelvic floor muscle exercise group were (44.83±9.01) mmHg, (4.31±1.75) mmHg, (130.46±10.00) mmHg, (19.94±4.30) s, (32.71±5.00) ml, (74.26±8.30) ml, (188.4±12.68) ml, (5.69±1.18) ml/kPa, (3.31±0.96) cm and (68.09±6.38) points respectively. The main effects of the changes of five indices, including anal resting pressure, rectal resting pressure, anal maximum systolic pressure, anal maximum systolic time and anal high pressure zone, were time. Significant differences were found in initial rectal capacity, sensory capacity of rectal defecation, maximum tolerance capacity of rectum, rectal compliance and total score of intestinal function in every time point of measurement in the biofeedback training group combined with pelvic floor muscle exercise group. They were significantly higher than those in the blank control group (P<0.05); the score of the biofeedback training group combined with pelvic floor muscle exercise group at one month after operation, perioperative period and 3 months after operation were significantly higher than those in pelvic floor muscle exercise group (P<0.05). Biofeedback training combined with pelvic floor muscle exercise reduced the incidence of low anterior resection syndrome of rectum (P<0.05). Conclusion: Biofeedback training combined with pelvic floor muscle exercise can significantly improve the sensory indicators of patients with mid-low rectal cancer, promote the recovery of intestinal function, and alleviate low anterior resection syndrome of rectal cancer patients, which is worthy of popularization and application.

[Screening different HPV genotypes infection and type-specific in cervical exfoliated cells of women in Yili area of Xinjiang Uygur Autonomous Region, China].

Objective: To investigate the infection status and genotype distribution of cervical human papillomavirus (HPV) in women of different ethnic groups and different ages in Yili, Xinjiang Uygur Autonomous Region (Xinjiang). Methods: By using the convenient sampling method, 54 760 women from November 2015 to May 2017 seeking for service in gynecological clinics in a general hospital in Yili, Xinjiang, were selected as the research subjects, and 3 445 samples of cervical mucous exfoliative cells were collected, and the social information of their ethnic and age was collected at the same time. The inclusion criteria were those with sexual life, cervical integrity, and ethnic groups for Han or Uygur or Kazak. PCR-reverse dot blot hybridization was used to detect HPV genotyping in exfoliated cells, and chi-square test was used to compare the difference of HPV positive rate among different ethnic groups. Then, according to ethnicity and age, the differences in positive rates of different ages and ethnic groups were compared in each layer. Results: The positive rate of HPV was 25.6% (882 cases), of which the Han, Uygur and Kazakh were 27.9% (564 cases), 22.9% (196 cases) and 21.6% (122 cases), and the difference was statistically significant (χ(2)=13.80, P=0.001). The most prevalent high-risk genotypes of Han women were HPV16/52/58, accounting for 24.8% (140 cases), 17.7% (100 cases) and 9.8% (55 cases), respectively. The most prevalent high-risk genotypes of Uygur women were HPV16/52/53, accounting for 34.2% (67 cases), 12.8% (25 cases), 9.2% (18 cases), respectively. The most prevalent high-risk genotypes of Kazak were HPV16/52/53, accounting for 37.7% (46 cases), 17.2% (21 cases), 12.3% (15 cases), respectively. The highest rate of HPV in Uygur patients aged ≥61 years was 41.5% (22 cases), and the lowest in group 36-40 years old, 15.9% (21 cases), the difference between different age groups was statistically significant (χ(2)=35.01, P<0.001). Conclusion: The positive rate of HPV infection among Han, Uygur and Kazak in Yili Prefecture of Xinjiang was different, and the HPV positive genotype differs among different ethnic groups.

[Correlation between mismatch repair proteins status and clinicopathological characteristics in sporadic colorectal cancer patients].

Objective: To explore the expression of mismatch repair (MMR) proteins in sporadic colorectal cancer (SCRC) patients, and its association with clinicopathological characteristics of SCRC. Methods: Patients with histologically confirmed colorectal cancer were consecutively recruited between December 2011 and June 2015 at Sun Yat-sen University Cancer Center. The exclusion criteria included multiple primary colorectal tumors, hereditary colorectal cancer (including Lynch syndrome, familial adenomatous polyposis), and the patients without the MMR proteins status tested. A total of 2 684 patients were included. Correlations of MMR proteins status and patients' demographics (including gender, age), tumor characteristics (site and differentiation) and TNM staging (excluding 315 SCRC patients receiving neoadjuvant therapy) were investigated. Results: The percentage of deficient MMR (dMMR) in these SCRC patients was 10.2%, and that of proficient MMR (pMMR) was 89.8%. The dMMR was more likely to be detected in younger (≤59 old years) SCRC patients compared to the elderly (>59 years) [12.7%(179/1 406)vs 7.5%(96/1 278), P<0.001]. The dMMR rate in right colon cancer was significantly higher than that in left colon cancer and rectal cancer [22.7%(151/664)vs 7.2%(69/956)vs 5.2%(55/1 064), P<0.001]. Among the various pathological types of SCRC, mucinous adenocarcinoma showed the highest rate of dMMR (24.4%), and neuroendocrine carcinoma the lowest rate of dMMR (0) (P<0.001). In addition, the proportions of dMMR in stage Ⅰ, stage Ⅱ, stage Ⅲ and stage Ⅳ SCRC were 9.7%, 16.5%, 8.5%, and 3.9%, respectively (P<0.001). There is no significant difference in the proportion of dMMR between male and female (11.0% vs 9.1%, P=0.114). Conclusion: dMMR status may be most likely to exist in younger (≤59 years) patients with stage Ⅱ right colon mucinous adenocarcinoma among SCRC.

Oxaliplatin and capecitabine concomitant with neoadjuvant radiotherapy and extended to the resting period in high risk locally advanced rectal cancer.

BACKGROUND: Conventional neoadjuvant chemoradiotherapy (CRT) is suboptimal for systemic control in locally advanced rectal cancer (LARC). To improve systemic control, we developed an alternative approach in which an intensified oxaliplatin and capecitabine (XELOX) chemotherapy regimen was administered concomitantly with radiation and extended to the resting period (consolidation chemotherapy) for high-risk LARC. The aim of the current study was to evaluate the short-term efficacy and toxicity of this strategy. METHODS: Patients with high-risk LARC were treated with CRT. Two cycles of XELOX were administered concomitantly with radiation. Thereafter, an additional cycle of the same regimen was administered during the resting period after completion of CRT. Tumor response, toxicities and surgical complications were recorded. RESULTS: This study includes 36 patients treated with the above strategy. All patients completed the planned concurrent CRT. Because of grade 3 toxicities, 2 patients were unable to complete the additional chemotherapy. Grade 3 toxicities were leucopenia (2.8 %), diarrhea (2.8 %) and radiodermatitis (2.8 %). All patients underwent optimal surgery with total mesorectal excision (TME) and a sphincter-saving procedure was performed in 27 patients (75 %). There was no perioperative mortality. Postoperative complications developed in 7 patients (19.4 %). Pathologic complete regression (pCR),"nearly pCR" (major regression), and moderate or minimal regression were achieved in 13 (36.1 %), 16 (44.4 %), and 7 patients (19.5 %), respectively. CONCLUSION: The preliminary results suggest that a XELOX regimen initially administered concomitantly with radiotherapy and then extended to the resting period in high-risk LARC patients is well tolerated. The strategy is highly effective in terms of pCR and nearly pCR rates, and thus warrants further investigation.

Celecoxib can prevent capecitabine-related hand-foot syndrome in stage II and III colorectal cancer patients: result of a single-center, prospective randomized phase III trial.

BACKGROUND: Hand-foot syndrome (HFS) is the most common adverse event induced by capecitabine. Some clinicians think that HFS is a type of inflammation limited to the hands and feet and can be prevented with a COX-2 inhibitor (celecoxib). METHODS: We designed a single-center, prospective randomized clinical trial to test the hypothesis. From August 2008 to December 2010, stage II and III colorectal cancer patients receiving capecitabine-based chemotherapy enrolled in the trial voluntarily. All patients were divided randomly into two groups treated with or without celecoxib. All adverse events were recorded. RESULTS: Grade 1 and grade 2 HFS were more common in the capecitabine group than in the capecitabine/celecoxib group (74.6% versus 57.4%, P = 0.034, 29.6% versus 14.7% P = 0.035). The use of celecoxib (P < 0.001, P = 0.003) and the level of dihydropyrimidine dehydrogenase (P = 0.048, P = 0.014) affected the incidence of grade 1 and 2 HFS, as determined by log-rank analysis. Multivariate Cox proportional hazards regression analysis indicated that the use of celecoxib was the only factor that affected the incidence of ≥ grade 1 HFS [Hazard Ratio (HR): 0.556, P = 0.001] and ≥ grade 2 HFS (HR: 0.414, P = 0.005). CONCLUSIONS: Celecoxib can be used effectively and safely to prevent capecitabine-related HFS.

Neuroprotective effect of neurotropin on chronic oxaliplatin-induced neurotoxicity in stage II and stage III colorectal cancer patients: results from a prospective, randomised, single-centre, pilot clinical trial.

BACKGROUND: Oxaliplatin is effective in adjuvant and first-line colorectal cancer chemotherapy. Oxaliplatin-induced severe chronic neurotoxicity is the main dose-limiting adverse event. No standard treatment for oxaliplatin-induced chronic neurotoxicity has been identified. MATERIALS AND METHODS: We conducted a prospective pilot clinical trial to explore whether neurotropin has neuroprotective effects on chronic neurotoxicity. From May 1, 2010 to May 1, 2011, 80 stage II and III colorectal cancer patients who were eligible to receive oxaliplatin-based chemotherapy voluntarily enrolled in the trial. The patients were randomly divided into two groups, one of which received neurotropin treatment. RESULTS: The patients in the control group experienced significantly ≥ grade 2 and ≥ grade 3 neurotoxicity (by NCI CTCAE grading) than those in the neurotropin group (60.9 vs. 21.1 %, for at least grade 2 neurotoxicity, P = 0.001; 39 vs. 2.7 %, for at least grade 3 neurotoxicity, P < 0.001). If neurotoxicity was assessed by oxaliplatin-specific neurotoxicity grading, the patients in the control group also experienced significantly more ≥ grade 2 neurotoxicity (51.2 vs. 12.5 %, P = 0.001). Neurotropin was the only factor that affected the incidence of ≥ grade 2 neurotoxicity in the multivariate Cox proportional hazards regression analysis. CONCLUSION: Neurotropin combined with oxaliplatin decreases chronic neurotoxicity effectively and safely.

[Progress in diagnosis and treatment of gastroparesis after colon cancer surgery].

At present, comprehensive treatment dominated by surgical procedures is an important measure for colon cancer to obtain the chance of cure. Surgical intervention, while removing the tumor, carries the risk of postoperative gastroparesis (PG) . Because of the low incidence rate and insignificant early clinical symptoms, early stage PG is often overlooked clinically. However, PG can increase the risk of malnutrition, delay postoperative antitumor treatment, and increase the risk of tumor recurrence and metastasis. This review focuses on the mechanisms, clinical risk factors, preventive measures, and advances in treatment of PG due to colon cancer. Aim to increase the clinician's adequate attention to PG in colon cancer and from a surgical point to reduce the risk of gastroparesis in colon cancer by optimizing the surgical strategy.

[Prognostic factors affecting the success of conversion chemotherapy in patients with unresectable liver metastases from initially colorectal cancer].

Objective: To investigate the factors affecting the success of conversion therapy in patients with initially unresectable colorectal cancer liver metastases (CRLM) in order to provide evidence-based medical evidence for formulating individualized treatment strategies for patients. Methods: A retrospective case-control study was used in this study. Clinical data of 232 patients with initially unresectable CRLM receiving first-line systemic treatment in Sun Yat-sen University Cancer Center from January 2013 to January 2020 were collected, including 98 patients of successful conversion and 134 patients of failed conversion as control. Conversion therapy scheme: 38 patients received FOLFOXIRI regimen chemotherapy (irinotecan, oxaliplatin, calcium folinate and fluorouracil), 152 patients received FOLFOX regimen (oxaliplatin, calcium folinate and fluorouracil), 19 patients received FOLRIRI regimen (irinotecan, calcium folinate and fluorouracil), 23 patients received systemic chemotherapy combined with fluorouridine hepatic artery infusion chemotherapy; 168 patients received targeted therapy, including 68 of bevacizumab and 100 of cetuximab. Logistics analysis was used to compare the factors affecting the success of conversion therapy. The Kaplan-Meier method was used to calculate progression-free survival (PFS), and the Log-rank test was used for survival comparison. Results: Among 232 patients, 98 patients had successful conversions and 134 patients had failed conversions with a successful conversion rate of 42.2%, meanwhile 30 patients underwent simple hepatectomy and 68 underwent hepatectomy combined with intraoperative radiofrequency ablation. After first-line chemotherapy, 111 patients (47.8%) were partial remission, 57 patients (24.6%) were stable disease, and 64 patients (27.6%) were progression disease. During the median follow-up of 18.8 (1.0-87.9) months, 148 patients were dead or with tumor progression. The median PFS time of patients with successful conversion was longer than that of patients with failed conversion (31.0 months vs. 9.9 months, P<0.001). Univariate analysis found that the bilobar distribution of liver tumors (P=0.003), elevated baseline carcinoembryonic antigen (CEA) levels (P=0.024), tumor invasion of the portal vein (P=0.001), number of metastatic tumor>8 (P<0.001), non-FOLFOXIRI (P=0.005), and no targeted therapy (P=0.038) were high risk factors for the failed conversion therapy. The results of multivariate logistics analysis indicated that the number of metastatic tumor >8 (OR=2.422, 95%CI: 1.291-4.544, P=0.006), portal vein invasion (OR=2.727, 95%CI: 1.237-4.170, P=0.008) were the independent risk factors for failed conversion therapy, while FOLFOXIRI regimen (OR=0.300, 95%CI: 0.135-0.666, P=0.003) and targeted drugs (OR=0.411, 95%CI: 0.209-0.809, P=0.010) were independent protective factors for successful conversion therapy. Conclusions: The number of metastatic tumor and portal vein invasion are key factors that affect the outcomes of conversion therapy for initially unresectable CRLM. If a patient can tolerate chemotherapy, a combination program of three-drug and targeted therapy is preferred for the active conversion therapy.

[Advances and challenges in neoadjuvant treatment for colorectal cancer liver metastasis].

Liver metastasis is the leading cause of death in patients with colorectal cancer. Since surgical resection alone has a high postoperative recurrence rate, neoadjuvant therapy as an important means is widely applied in order to reduce recurrence and improve survival. Progress has been achieved in many aspects of neoadjuvant therapy in colorectal cancer liver metastasis, such as eligible patients selection, optimal regimens and courses of chemotherapy. However, controversies still remain regarding the standards of resectability of lesions and the application of targeted drugs. Individualized treatments could be developed based on multidisciplinary teamwork to achieve the goal of 'resources integration and treatment stratification'.

Phase II study of pre-operative radiotherapy with capecitabine and oxaliplatin for rectal cancer and carcinoembryonic antigen as a predictor of pathological tumour response.

This study investigated the efficacy and tolerability of pre-operative radiotherapy with concurrent capecitabine and oxaliplatin in patients with rectal cancer. Forty-seven patients with rectal adenocarcinoma (stages T3 - T4; node-positive) were enrolled and received radiotherapy (46 Gy in 23 fractions) in combination with capecitabine (1000 mg/m(2) twice daily on days 1 - 14 and 22 - 35) and oxaliplatin (130 mg/m(2) on days 1 and 22) (XELOX regimen). The main endpoints were safety and efficacy, as assessed by pathological complete response (pCR). All patients received pre-operative chemoradiotherapy (CRT) as planned. The most common severe toxicity was diarrhoea (12.8%); post-operative complications were rare (9.8%). The pCR rate was 20.9% in all patients and 34.8% in patients with normal pre-CRT serum carcinoembryonic antigen (CEA < or = 5 ng/ml) level, compared with 5.0% in the patients with elevated CEA (> 5 ng/ml). In conclusion, pre-operative radiotherapy with concurrent XELOX regimen in rectal cancer patients is feasible and effective. Serum CEA may be a suitable predictor of pCR.

[Comparison of long-term efficacy between watch and wait strategy and total mesorectal excision in locally advanced rectal cancer patients with clinical complete response after neoadjuvant therapy].

Objective: To compare long-term efficacy between watch and wait (W&W) strategy and total mesorectal excision (TME) in patients who were diagnosed with locally advanced rectal cancer (LARC) and attained clinical complete response (cCR) after neoadjuvant chemoradiotherapy (nCRT). Methods: A retrospective cohort study was carried out. A total of 238 patients with stage II-III LARC exhibiting cCR after nCRT in Sun Yat-sen University Cancer Center from September 16, 2010 to January 9, 2018 were enrolled. Patients who were diagnosed with other malignant tumor within 5 years, did not receive regular follow-up in our center for more than 1 year and had no complete examination items after nCRT were excluded. Of 238 patients, 151 were male and 87 were female with a median age of 57 (27-83) years old. According to TNM stage, 61 cases were cII, 177 cases were cIII. Concurrent chemoradiotherapy (CCRT) was performed in 20 patients. CCRT plus induction/consolidated chemotherapy was performed in 218 patients. Intensity-modulated radiotherapy (IMRT) was applied to radiotherapy. The median radiation dose was 50 Gy/25 Fr for both the primary tumor and clinical target volumes, and the total dose was 45.0 to 50.6 Gy for 227 patients. In 27 patients, single-agent fluorouracil or capecitabine was used as concurrent chemotherapy. But in the other 211 patients, a combined regimen of oxaliplatin and fluorouracil or capecitabine was used. After nCRT, 59 and 179 patients received W&W (W&W group) and TME 6-12 weeks later (TME group), respectively. After the ending of treatment, patient was interviewed one time every 3 months and after 3 years, one time every six months. Overall survival (OS) rate, distant-metastasis-free survival (DMFS) rate, and local-recurrence-free survival (LRFS) rate were compared between two groups. The salvage treatment and sphincter preservation rate were analyzed. The survival curve was drawn with Kaplan-Meier method and evaluated by log-rank method. Results: In the cases treated with TME, the median interval from nCRT to surgery was 59 days. The postoperative pCR rate was 63.1%(113/179). The median follow-up time of the whole cohort was 41.8 (12.0-99.0) months. The 3-year and 5-year OS rates were 98.4% and 96.5%; the 3-year and 5-year LRFS rates were 96.5% and 96.5%; the 3- and 5-year DMFS rates were 91.0% and 87.9%, respectively. The 3-year OS rates in the W&W group and the TME group were 100% and 97.9%; the 5-year OS rates in W&W group and the TME group were 90.6% and 97.9% (P=0.339); The 3-year local recurrence rate (LRR) in the W&W group was 12.9% (7 cases recurred within 2 years), which was significanthy higher then that in the TME group (0.6%, P=0.003). Salvage surgery was successful in 5/6 cases. After salvage surgery, LRFS rate was not significantly different between the two groups (P=0.137). The 3-year DMFS rate in the W&W group and the TME group were 88.4% and 81.1%, whose difference was not significant (P=0.593). Recurrence with simultaneous metastasis was seen in 3/7 cases of the W&W group. The sphincter was preserved in 89.8% (53/59) of patients in the W&W group, which was significantly higher than 73.7% (132/179) in the TME group (P<0.001). When distance of tumor from the anal verge was ≤ 5 cm, the sphincter preservation rate (SPR) in the W&W group was 88.0% (44/50), which was significantly higher than the 54.4% (56/103) in the TME group (P<0.001). Conclusions: W&W is safe and feasible for patients with LARC and cCR after nCRT. The results should be verified by further clinical trials.

Elevated expressions of MMP7, TROP2, and survivin are associated with survival, disease recurrence, and liver metastasis of colon cancer.

PURPOSE: Colorectal cancer is one of the most common cancers worldwide. We tested the hypothesis that differences in the expression of certain molecular markers of colon cancer may account for different clinical outcomes. METHODS: Tissue microarray technology was used to assay the expression of 17 biological markers [beta-catenin, CD44v7, c-myc, cyclin D1, estrogen receptor beta, mitogen-activated protein kinase/extracellular signal-regulated kinase, maspin, matrix metalloproteinase-7 (MMP7), p53, Pin1, peroxisome proliferators-activated receptor-gamma, survivin, T cell transcription factor 4 (TCF4), transforming growth factor beta receptor II (TGFbetaR II), TGFbeta, TROP2, and Wnt] by immunohistochemistry in 620 colon cancer patients. The Cox proportional hazards regression model was applied to analyze the lifetime data, including time to death, time to recurrence, and time to liver metastasis. RESULTS: All the markers were present at significantly higher expression levels in tumor specimens than in normal colonic specimens. Kaplan-Meier analysis showed that high expression of TROP2, MMP7, and survivin were related to decreased survival; TCF4 and TROP2 were related to disease recurrence; and CD44v7, cyclin D1, MMP7, p53, survivin, and TCF4 were related to liver metastasis. However, the results of the multivariate analysis only showed that expression of MMP7, survivin, and TROP2 were significant predictors of lower patient survival, while TROP2 and MMP7 were significantly related to disease recurrence and liver metastasis, respectively. CONCLUSIONS: We conclude that elevated survivin, MMP7, and TROP2 expression levels are related to decreased survival. In addition, elevated MMP7 and TROP2 expression levels are predictors of disease recurrence and liver metastasis, respectively.

A false transmitter at excitatory synapses.

We used the low affinity N-methyl-D-aspartate (NMDA) receptor agonist D-glutamate to study the time course of synaptic activation of NMDA receptors. Repetitive stimulation of cultured hippocampal neurons loaded with D-glutamate caused a dramatic shortening of both the rising and decaying phases of NMDA receptor excitatory postsynaptic currents (EPSCs) evoked by autaptic stimulation. The EPSC time course was mimicked by NMDA receptor currents evoked in outside-out patches by 1-4 ms applications of D-glutamate. Thus, D-glutamate can be released as a false transmitter. The results show that both the rise and fall of the NMDA receptor EPSCs are normally controlled by the slow unbinding rate of the natural neurotransmitter and that the concentration of free transmitter is elevated in the cleft for only a few milliseconds after release.

Glial glutamate transporter 1 regulates the spatial and temporal coding of glutamatergic synaptic transmission in spinal lamina II neurons.

Glutamatergic synaptic transmission is a dynamic process determined by the amount of glutamate released by presynaptic sites, the clearance of glutamate in the synaptic cleft, and the properties of postsynaptic glutamate receptors. Clearance of glutamate in the synaptic cleft depends on passive diffusion and active uptake by glutamate transporters. In this study, we examined the role of glial glutamate transporter 1 (GLT-1) in spinal sensory processing. Excitatory postsynaptic currents (EPSCs) of substantia gelatinosa neurons recorded from spinal slices of young adult rats were analyzed before and after GLT-1 was pharmacologically blocked by dihydrokainic acid. Inhibition of GLT-1 prolonged the EPSC duration and the EPSC decay phase. The EPSC amplitudes were increased in neurons with weak synaptic input but decreased in neurons with strong synaptic input upon inhibition of GLT-1. We suggest that presynaptic inhibition, desensitization of postsynaptic AMPA receptors, and glutamate "spillover" contributed to the kinetic change of EPSCs induced by the blockade of GLT-1. Thus, GLT-1 is a key component in maintaining the spatial and temporal coding in signal transmission at the glutamatergic synapse in substantia gelatinosa neurons.

Roles of alpha1- and alpha2-adrenoceptors in the nucleus raphe magnus in opioid analgesia and opioid abstinence-induced hyperalgesia.

Noradrenaline and alpha-adrenoceptors have been implicated in the modulation of pain in various behavioral conditions. Noradrenergic neurons and synaptic inputs are present in neuronal circuits critical for pain modulation, but their actions on neurons in those circuits and consequently the mechanisms underlying noradrenergic modulation of pain remain unclear. In this study, both recordings in vitro and behavioral analyses in vivo were used to examine cellular and behavioral actions mediated by alpha1- and alpha2-adrenoceptors on neurons in the nucleus raphe magnus. We found that alpha1- and alpha2-receptors were colocalized in the majority of a class of neurons (primary cells) that inhibit spinal pain transmission and are excited during opioid analgesia. Activation of the alpha1-receptor depolarized whereas alpha2-receptor activation hyperpolarized these neurons through a decrease and an increase, respectively, in potassium conductance. Blockade of the excitatory alpha1-receptor or activation of the inhibitory alpha2-receptor significantly attenuated the analgesia induced by local opioid application, suggesting that alpha1-receptor-mediated synaptic inputs in these primary cells contribute to their excitation during opioid analgesia. In the other cell class (secondary cells) that is thought to facilitate spinal nociception and is inhibited by analgesic opioids, only alpha1-receptors were present. Blocking the alpha1-receptor in these cells significantly reduced the hyperalgesia (increased pain) induced by opioid abstinence. Thus, state-dependent activation of alpha1-mediated synaptic inputs onto functionally distinct populations of medullary pain-modulating neurons contributes to opioid-induced analgesia and opioid withdrawal-induced hyperalgesia.

mu-Opposing actions of the kappa-opioid receptor.

Pharmacological studies and recent research using genetic approaches have indicated that most actions of exogenous opioids, such as morphine, are mediated through the mu-opioid receptor. By contrast, the function of the kappa-opioid receptor in opioid actions largely remains unclear. In this article, Zhizhong Z. Pan discusses the accumulating evidence that activation of the kappa-receptor antagonizes various mu-receptor-mediated actions in the brain, including analgesia, tolerance, reward and memory processes. The neural mechanism for this potentially ubiquitous mu-opposing function of the kappa-receptor is believed to involve distinct locations of the two opioid receptors on physiologically different cell types in local neuronal networks that are implicated in an opioid action.

Mu-opioid-mediated inhibition of glutamate synaptic transmission in rat central amygdala neurons.

The central nucleus of the amygdala (CeA) plays an important role both in stimulus-reward learning for the reinforcing effects of drugs of abuse and in environmental condition-induced analgesia. Both of these two CeA functions involve the opioid system within the CeA. However, the pharmacological profiles of its opioid receptor system have not been fully studied and the synaptic actions of opioid receptors in the CeA are largely unknown. In this study with whole-cell voltage-clamp recordings in brain slices in vitro, we examined actions of opioid agonists on glutamate-mediated excitatory postsynaptic currents (EPSCs) in CeA neurons. Opioid peptide methionine-enkephalin (ME; 10 microM) produced a significant inhibition (38%) in the amplitude of evoked EPSCs, an action mimicked by the mu-opioid receptor agonist [D-Ala(2),N-MePhe(4),Gly-ol(5)]-enkephalin (DAMGO; 1 microM, 44%). Both effects of ME and DAMGO were abolished by the mu receptor antagonist CTAP (1 microM), suggesting a mu receptor-mediated effect. Neither delta-opioid receptor agonist [D-Pen(2),D-Pen(5)]-enkephalin (1 microM) nor kappa-opioid receptor agonist U69593 (300 nM) had any effect on the glutamate EPSC. ME significantly increased the paired-pulse ratio of the evoked EPSCs and decreased the frequency of miniature EPSCs without altering the amplitude of miniature EPSCs. Furthermore, the mu-opioid inhibition of the EPSC was blocked by 4-aminopyridine (4AP; 100 microM), a voltage-dependent potassium channel blocker, and by phospholipase A(2) inhibitors AACOCF(3) (10 microM) and quinacrine (10 microM). These results indicate that only the mu-opioid receptor is functionally present on presynaptic glutamatergic terminals in normal CeA neurons, and its activation reduces the probability of glutamate release through a signaling pathway involving phospholipase A(2) and the presynaptic, 4AP-sensitive potassium channel. This study provides evidence for the presynaptic regulation of glutamate synaptic transmission by mu-opioid receptors in CeA neurons.

Synaptic properties and postsynaptic opioid effects in rat central amygdala neurons.

An important output of amygdaloid nuclei, the central nucleus of the amygdala (CeA) not only mediates negative emotional behaviors, but also participates in the stimulus-reward learning and expression of motivational aspects of many drugs of abuse, and links environmentally stressful conditions such as fear to endogenous pain-inhibiting mechanisms. The endogenous opioid system in the CeA is crucial for both reward behaviors and environmental stress-induced analgesia. In this study using whole-cell voltage-clamp recordings, we investigated synaptic inputs and the postsynaptic effects of opioid agonists in CeA neurons. We found that synaptic inputs evoked within the CeA were mediated by both glutamate and GABA, but those evoked from the basolateral amygdala were primarily glutamatergic. Based on membrane properties, three types of cells were characterized. Type A neurons had no spike accommodation while type B neurons displayed characteristic accommodating response. Type A neurons were further classified as either A1 or A2, based on differences in resting membrane potential and the amplitude of after-hyperpolarizing potential. micro-Opioid receptor agonists hyperpolarized a subpopulation of CeA neurons, of which the vast majority was type A1. This micro agonist-induced hyperpolarization was mediated by the opening of inwardly rectifying potassium channels. In contrast, the kappa-opioid receptor agonist hyperpolarized only type B neurons. These results illustrate three types of CeA neurons with distinctive membrane properties and differential responses to opioid agonists. They may represent functionally distinct CeA cell groups for the integration and execution of CeA outputs in the aforementioned CeA functions.

Endogenous opioid-mediated inhibition of putative pain-modulating neurons in rat rostral ventromedial medulla.

The rostral ventromedial medulla is a critical relay for midbrain regions, including the periaqueductal gray and nucleus cuneiformis, that control nociception at the spinal cord. Opioid-containing neurons and terminals are concentrated in both the periaqueductal gray and the rostral ventromedial medulla in the rat. However, the function of endogenous opioid peptides within the medulla in pain modulation is unclear. In this study, bicuculline (30-50 ng) or morphine (5 micrograms) microinjected into the periaqueductal gray inhibited the tail-flick reflex and the firing of on-cells (cells that increase firing just before tail flick) in the medulla. Iontophoretically applied naloxone (20 or 30 nA), which blocked the inhibition of on-cell firing induced by iontophoresis of morphine (20 or 30 nA), consistently reduced the on-cell inhibition produced by bicuculline or morphine microinjected into the periaqueductal gray. Naloxone did not reduce the inhibition of on-cell firing induced by iontophoretically applied clonidine (10 or 20 nA), an alpha 2 adrenoceptor agonist. The firing of off-cells (cells that pause in firing just prior to tail-flick) in the medulla was increased by bicuculline applied in the periaqueductal gray and was not affected by naloxone. The present results suggest that when activation of neurons in the periaqueductal gray produces antinociception, endogenous opioid peptides are released in the rostral ventromedial medulla and selectively inhibit on-cells, which presumably have a facilitating action on spinal nociceptive transmission. This action is proposed to be critical for the behavioral antinociception induced by bicuculline or morphine in the periaqueductal gray.