Does Early Polypoid Colorectal Cancer with Depression Have a Pathway Other than Adenoma-Carcinoma Sequence?

In the carcinogenesis of colorectal cancer, the concept of adenoma-carcinoma sequence is widely accepted. In this pathway, polypoid adenoma develops into early polypoid cancer and then progresses to advanced cancer. Alternatively, some groups insist that in the de novo pathway in which early cancers develop without preexisting adenoma, flat or depressed early cancers develop into advanced cancer. According to these two different concepts of carcinogenesis, early polypoid cancers may include two distinct types of lesions, early polypoid cancers without central depression via the adenoma-carcinoma sequence and early polypoid cancers with central depression via de novo carcinogenesis. We analyzed 45 submucosal cancer specimens histologically diagnosed as polypoid by clinicopathological features and K-ras mutation in early polypoid cancers with and without depression to clarify whether there was a difference between the two groups. No significant difference in clinicopathological features was found between the two groups. Also, a high incidence of K-ras mutation was observed in both groups. This suggests that early polypoid cancers with depression have a similar genetic background to polypoid cancers without depression, which follows the adenoma-carcinoma sequence. It is possible that whether or not the tumor has a depression does not indicate the distinct pathway of colorectal carcinogenesis.

Prospective Surveillance Effectively Reduced Rates of Surgical Site Infection Associated With Elective Colorectal Surgery at a University Hospital in Japan

At a university hospital in Japan, the introduction of prospective surveillance and subsequent interventions was effective in reducing the rate of surgical site infection associated with elective colorectal surgery from 27.5% to 17.8% of surgeries. Japan should both recognize the importance of broader surveillance for surgical site infection and establish its own nationwide surveillance database.

Hypoxia enhances colon cancer migration and invasion through promotion of epithelial-mesenchymal transition

BACKGROUND

A hypoxic environment exists in most solid tumors because in rapidly growing tumors, the development of angiogenic vasculature is heterogenous, usually not enough to overcome the necessary oxygen supply. In an ischemic condition, cancer cells develop escape mechanisms to survive and leave the unfavorable environment. That result in the acquisition of increased potential for local invasion and evasion to distant organs. However, the escape mechanisms of cancer cells from hypoxic stress have not been fully characterized.

MATERIALS AND METHODS

The human colon cancer cell line LoVo was cultured in hypoxia, and the adhesive and migratory properties were analyzed. The expression of cell surface and cytoplasmic molecules was also investigated.

RESULTS

Under hypoxic conditions, cells developed epithelial-mesenchymal transition. The expression levels of α2, α5, and β1 integrins were significantly upregulated and, as a consequence, the ability to adhere to and migrate on collagen and fibronectin was increased. On the other hand, the expression of 67-kDa laminin receptor and the abilities to adhere to and migrate on laminin were decreased. Additionally, the expression of CXCR4 was significantly increased on cells cultured in hypoxia, and the chemotactic activity to stromal cell-derived factor 1α was remarkably increased.

CONCLUSIONS

Hypoxic stress induced active epithelial-mesenchymal transition in colon cancer cells, with the typical morphologic and functional changes. These morphologic and functional changes of β1 integrins, the 67-kDa laminin receptor, and CXCR4 may be essential for the acquisition of the invasive and metastatic features in colorectal cancer.

Vagus nerve preservation results in visceral fat maintenance after distal gastrectomy

BACKGROUND/AIMS

Although preservation of the vaguas nerve is recommended in surgery for earlystage gastric cancer, the physiological effect of vagotomy on the postoperative course has not been well documented. We assessed the effect of vagotomy on the change in fat volume after gastrectomy.

METHODOLOGY

Subcutaneous fat area (SFA) and visceral fat area (VFA) were separately measured in computed tomographic images taken before and more than 6 months after surgery, using Fat Scan software. The ratios of postoperative/ preoperative values of these two fat areas as well as body weight were calculated in 45 patients who underwent DG with (n=24) or without (n=21) vagotomy.

RESULTS

Vagotomy did not affect the change in body weight (91.3±1.7% vs. 92.1±1.7%). In patients with vagotomy, VFA was reduced to 59.0±5.1%, which was significantly greater than the reduction in SFA (74.3±8.7%, p=0.042). In contrast, the reduction ratios of VFA and SFA were equal in vagus nerve-preserved patients (78.4±6.7% vs. 78.2±6.9%, p=0.97).

CONCLUSIONS

The vagus nerve may have a function to locally regulate the intra-abdominal fat volume and preservation of the vagus nerve results in the maintenance of visceral fat after DG.

A 1cm distal bowel margin is safe for rectal cancer after preoperative radiotherapy

BACKGROUND/AIMS

Although guidelines recommend a 2 cm distal margin in sphincter-saving operations for rectal cancer, some studies have shown that it may be decreased to 1cm after preoperative radiotherapy. At the present time, there are no established guidelines that suggest a specific distal safety margin for rectal cancer after preoperative radiotherapy. This study aims to examine whether preoperative radio therapy can reduce the distal safety margin in the treatment of lower rectal cancers.

METHODOLOGY

We examined the distal spread by H&E and immunohistochemical staining of CAM5.2 (epithelial marker) in serial sections of surgically resected specimens. To evaluate the extent of distal intramural spread, we defined the "DS length" as the distance between the microscopically defined distal tumor border and the distal spread. We compared the DS length between 20 patients who underwent preoperative radiotherapy followed by surgery (Rad (+) group) and 20 surgery-alone (Rad (-)group).

RESULTS

The average DS length was significantly smaller in the Rad (+) group (3.2mm) than in the Rad (-) group (6.3mm) (p=0.028). Furthermore,the greatest DS length was 5.8mm in the Rad (+) group,but 11.5mm in the Rad (-) group. No patient showed a DS length of over 1cm in the Rad (+) group.

CONCLUSIONS

These results suggested that the safety margin may be reduced to 1cm by preoperative radiotherapy.Therefore, preoperative radiotherapy may extend the indications for sphincter-saving operation.

Adiponectin receptor 2 is negatively associated with lymph node metastasis of colorectal cancer

Adiponectin is a hormone secreted by adipose tissue and has a variety of functions including the inhibition of tumor growth. The expression and function of the two major adiponectin receptors, AdipoR1 and AdipoR2, in malignant tissue have not been well characterized. In the present study, we evaluated the mRNA levels of AdipoR1 and AdipoR2 expression in 48 surgically resected colorectal cancer specimens, as well as normal colonic mucosa, by quantitative RT-PCR. The values obtained were standardized by β-actin mRNA, and the correlation between their relative expression levels and the clinicopathological characteristics of the patients was examined. The relative expression levels of AdipoR1 and AdipoR2 were significantly reduced in cancer tissue compared with normal tissue (AdipoR1: 0.97±0.39 vs. 1.37±0.41, P<0.0001; AdipoR2: 0.92±0.31 vs. 1.60±0.46, P<0.0001). AdipoR1 and AdipoR2 levels were further reduced in tumors with nodal metastases and the difference was statistically significant in the case of AdipoR2 (0.79±0.27 vs. 1.02±0.30, P=0.012). The results of this study demonstrated that the expression levels of adiponectin receptors are reduced in cancer specimens compared to normal tissue, indicating a downregulation in the course of the development and progression of colorectal cancer. Since adiponectin is abundantly present in the whole body and has inhibitory effects on cancer cells, this downregulation of the receptors may be an escape mechanism of malignant cells from the suppressive effects of adiponectin.

Immunohistochemical detection of CD133 is associated with tumor regression grade after chemoradiotherapy in rectal cancer

CD133 has been identified as a putative cancer stem cell (CSC) marker in various cancers including colorectal cancer. The relation between CD133 expression and biological characteristics of colorectal cancer remains to be clarified. Protein expression of CD133 was immunohistochemically evaluated in surgical specimens of 225 patients with colorectal cancer who were treated by surgery, as well as those of 78 patients with rectal cancer who received preoperative chemoradiotherapy (CRT) followed by curative resection. The correlation between CD133 expression and clinicopathological features, tumor recurrence and overall survival was analyzed in both populations. Among 225 colorectal cancers without CRT, 93 (41.3%) were positive for CD133 expression, which was enhanced in cases with advanced T stage and venous invasion. Moreover, CD133 was positive in 47 (60.3%) of 78 cases with CRT, which was significantly higher than the CD133-positive rate in non-CRT specimens (P=0.05). Expression of CD133 was independently correlated with the histological tumor regression grade (P<0.01). These results suggest that CD133 is not a distinctive colorectal CSC marker; expression of CD133 is suggested to be one of the key factors associated with resistance to CRT in colorectal cancer.

Synchronous and metachronous lung metastases in patients with colorectal cancer: A 20-year monocentric experience

There is little information regarding the recent trend of synchronous and metachronous pulmonary metastases in patients with primary colorectal cancer. We investigated patients with sporadic colorectal cancer who underwent surgery in our department between 1990 and 2009. Clinicopathological parameters of primary cancer and lung metastases and survival time were retrospectively reviewed. Of the 2,286 patients included in this study, 64 (2.8%) had synchronous lung metastases at the time of colorectal surgery. A total of 18 patients (28%) received pulmonary metastasectomy for these lesions with curative intent. Out of 2,082 curatively operated cases, 212 (10.2%) developed metachronous lung metastases. The frequency of synchronous and/or metachronous lung metastases detected in curative cases increased from 8.9% in the 1990s to 11.9% in the 2000s (p=0.03). Among predictive factors for metachronous lung metastases, the presence of distant organ metastases, i.e. initial stage IV, significantly increased over time. Notably, patients with unresectable metachronous lung metastases in the 2000s, characterized by smaller size, exhibited more favorable prognosis than in the 1990s (p=0.003). Recent improvement of imaging modalities is considered to have facilitated the prompt diagnosis of lung metastases. Moreover, marked progress in multidisciplinary treatment has presumably achieved more favorable prognosis in an increasing number of patients with advanced colorectal cancer.

Analysis for the combination expression of CK20, FABP1 and MUC2 is sensitive for the prediction of peritoneal recurrence in gastric cancer

Prediction of peritoneal recurrence in gastric cancer patients is important for application of adjuvant chemotherapy. After surgery, occasional patients have peritoneal recurrence despite negative cytology of the peritoneal washings. Thus, molecular detection of a subliminal number of cancer cells in peritoneal washings may overcome the sensitivity limitation of conventional cytology. In this study, expressions of five specific marker genes, namely, TFF1, TFF2, CK20, FABP1 and MUC2, were evaluated for their usefulness as markers of micro-dissemination. It was found that reverse transcriptase-polymerase chain reaction for these five genes yielded results highly specific for the depth of invasion and disease stage. Furthermore, the expression of CK20, FABP1 and MUC2 was a reliable prognostic indicator of peritoneal metastasis. Our results suggest that evaluation of the expression of CK20, FABP1 and MUC2 in peritoneal washings is a useful tool for identifying patients at high risk of peritoneal recurrence who may need adjuvant chemotherapy.

[FOLFOX as adjuvant chemotherapy after curative resection of distant metastatic lesions in patients with colorectal cancer]

We investigated the effectiveness of prophylactic FOLFOX after curative resection of synchronous metastases in patients with colorectal cancer (CRC). Clinicopathological information including postoperative chemotherapy, such as a therapeutic regimen, relapse-free survival (RFS), site of recurrence, etc., was retrospectively analyzed in 116 CRC patients with synchronous distant metastases, and 63 patients with metachronous metastases who had received surgery in our hospital between 2000 and 2009. Fifty-three patients (84%) out of 63 without adjuvant chemotherapy, and 38 (83%) out of 46 patients that received oral or intravenous 5-fluorouracil (5-FU) (alone or with leucovorin (LV)or isovorin) developed recurrent tumor(s) afterwards. The median RFSs were 119 and 281 days, respectively. By contrast, a single patient among 6 who underwent FOLFOX (up to 12 therapeutic courses) showed recurrence 476 days after surgery. The RFS of the FOLFOX was significantly higher than that of the 5-FU (+LV) or surgery alone (p=0. 03, p=0. 007, respectively). In conclusion, the FOLFOX regimen is more beneficial for CRC patients with synchronous metastasis as adjuvant chemotherapy than 5-FU (+LV) or other followup strategies.

Long-term results of endovascular treatment for splenic artery aneurysms

AIM

The aim of this paper was to evaluate our single-center experience of the management of splenic artery aneurysm (SAA), with particular attention to the long-term results of endovascular treatment.

METHODS

Thirty-eight patients with the diagnosis of SAA at the Tokyo University Hospital during the past 23 years were retrospectively reviewed. Interventions were considered for patients with SAA>2 cm in diameter. Nine patients were treated by transcatheter embolization (TE), and 8 by open surgical repair (SR). Twenty-one patients were observed (OB). TE was performed with microcoils placed distal and proximal to the aneurysm in the afferent artery to isolate the aneurysm.

RESULTS

In the TE group, the primary technical success rate was 100%. No 30-day mortality or any catheter-related complication was observed. The median length of hospital stay after TE, excluding one patient who required further surgery, was shorter than that after SR (8 versus 16 days, P=0.001). During follow-up (median =45 months), no patient died and no recurrence of SAA was observed. In the SR group, all aneurysms were repaired successfully without any severe complication, and no aneurysm-related death occurred during follow-up (median =57 months). In the OB group, no aneurysm rupture or increase in aneurysm size was observed during follow-up (median =35 months).

CONCLUSION

TE provided good early and long-term results, comparable to those obtained with conventional SR. In addition, TE had several advantages associated with its minimal invasiveness. TE by the isolation technique could be the first-line strategy for all SAA requiring treatment.

Is surveillance endoscopy necessary after colectomy in ulcerative colitis?

The role of surveillance endoscopic followup in colectomized patients with long standing total colitis is controversial. Here, we aimed to clarify its usefulness for the early detection of dysplasia and cancer in this group of patients. Ninety-seven colectomised UC patients followedup by surveillance endoscopy were retrospectively investigated by reviewing the pathological reports. Patients had received either subtotal colectomy and ileo-rectal anastomosis (IRA) or total proctocolectomy and ileal anal anastomosis (IPAA). Definite dysplasia was diagnosed in 4 patients, who had received IRA; among them, 2 were carcinoma with submucosal invasion, and one was a high-grade dysplasia. Postoperative surveillance endoscopy is useful for the detection of early cancer in the remaining colonic mucosa of UC patients, and those receiving IRA, in which rectal mucosa is left intact, would be good candidates. However, its effectiveness for patients receiving IPAA, in which the rectal mucosa is resected, needs further investigation.

FOLFOX as adjuvant chemotherapy after curative resection of distant metastases in patients with colorectal cancer

OBJECTIVES

The prophylactic effect of FOLFOX regimen, a standard regimen for unresectable colorectal cancer (CRC), was investigated in the adjuvant setting of CRC cases with distant metastases.

METHODS

The study population included 116 CRC patients with synchronous metastases and 91 patients with metachronous metastases who had undergone curative operation in our hospital between 2000 and 2009. Clinicopathological parameters of CRC, postoperative chemotherapeutic regimen, recurrence rate, and relapse-free survival (RFS) were analyzed retrospectively.

RESULTS

After resection of CRC and synchronous metastases, 53 (84%) out of 63 patients without chemotherapy, and 38 (83%) out of 46 that received 5-fluorouracil (5-FU) alone or with leucovorin (LV) developed recurrent tumors. By contrast, only 1 (17%) among 6 patients who underwent FOLFOX treatment showed recurrence. The FOLFOX group exhibited significantly improved RFS as compared to the 5-FU (+ LV) or surgery-alone group (p = 0.03, p = 0.007, respectively). On the other hand, in patients with metachronous metastases, tumor-relapse rate and RFS were not significantly influenced by post-metastasectomy therapies.

CONCLUSIONS

In this retrospective analysis, the adjuvant administration of FOLFOX appeared to reduce the risk of relapse in a small group of CRC patients with synchronous metastases. Prospective randomized trials will be required to confirm the benefits of this management strategy.

A case of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease) with multiple polyps arising in the cecum and appendix

We present the case of a 32-year-old female with cecal and appendiceal polyps that were removed by laparoscopy-assisted surgery. She also had recurrent nosebleeds due to telangiectases in the nasal mucosa and arteriovenous malformations in the lung, all of which contributed to the diagnosis of hereditary hemorrhagic telangiectasia.

Density of CD4(+) and CD8(+) T lymphocytes in biopsy samples can be a predictor of pathological response to chemoradiotherapy (CRT) for rectal cancer

Background

Although preoperative radiotherapy (RT) is widely used as the initial treatment for locally advanced rectal cancer (RC) in the neoadjuvant setting, factors determining clinical response have not been adequately defined. Radiosensitivity has recently been shown to be greatly affected by immune function of the host.

Methods

In 48 cases of advanced RC, we retrospectively examined the density of tumor infiltrating CD4(+) and CD8(+) T cells using immunohistochemical staining of biopsy samples before CRT, and examined the correlation with tumor response.

Results

The numbers of both CD4(+) and CD8(+) tumor-infiltrating lymphocytes (TIL) in pre-CRT biopsy samples were strongly correlated with tumor reduction ratio evaluated by barium enema. Moreover, the densities of CD4(+) and CD8(+) TIL were significantly associated with histological grade after CRT. The density of CD8(+) TIL was an independent prognostic factor for achieving complete response after CRT.

Conclusions

In RC patients, T lymphocyte-mediated immune reactions play an important role in tumor response to CRT, and the quantitative measurement of TIL in biopsy samples before CRT can be used as a predictor of the clinical effectiveness of CRT for advanced RC.

Intratumoral injection of interleukin-2 augments the local and abscopal effects of radiotherapy in murine rectal cancer

Recent studies have suggested that tumor shrinkage in response to radiotherapy (RT) is greatly dependent on the host immune response. A Balb/c mouse model of simultaneous subcutaneous tumor and liver metastasis of Colon26 was prepared and, after irradiation of the subcutaneous tumor (2 Gy × 5 day × 2 cycles), interleukin-2 (IL-2) (2 × 10(4) U) was injected intra-tumorally, and the fate of both the subcutaneous tumor and liver metastatic lesions was evaluated. Intratumoral injection of IL-2 greatly enhanced the anti-tumor effects of RT and completely eradicated the established subcutaneous tumor. Interestingly, although RT was given locally to the subcutaneous tumor, liver metastasis formation was also inhibited in mice receiving only local RT. More impressively, the combination of RT + IL-2 completely inhibited liver metastasis formation. Splenocytes in mice receiving RT + IL-2 contained a higher percentage of CD4(+) T cells, but lower percentages of CD4(+)CD25(+) regulatory T cells and CD11b(+) Gr-1(+) myeloid-derived suppressor cells. Immunohistochemical investigation of human rectal cancer revealed that the density of CD8(+) cells infiltrating into irradiated rectal tumor was positively associated with a lower frequency of distant metastasis as well as histological response grade. Local administration of IL-2 not only enhances shrinkage of the irradiated tumor itself, but can also suppress the development of distant metastasis located outside the RT field, possibly though the induction of a systemic T cell response. Augmentation of T-cell-mediated antitumor immunity during RT might be critical for improvement of the clinical efficacy of neoadjuvant RT for the treatment of advanced rectal cancer.

Predicting ulcerative colitis-associated colorectal cancer using reverse-transcription polymerase chain reaction analysis

BACKGROUND

Widespread genetic alterations are present not only in ulcerative colitis (UC)-associated neoplastic lesions but also in the adjacent normal colonic mucosa. This suggests that genetic changes in nonneoplastic mucosa might be effective markers for predicting the development of UC-associated cancer (UC-Ca). This study aimed to build a predictive model for the development of UC-Ca based on gene expression levels measured by reverse-transcription polymerase chain reaction (RT-PCR) analysis in nonneoplastic rectal mucosa.

PATIENTS AND METHODS

Fifty-three UC patients were examined, of which 10 had UC-Ca and 43 did not (UC-NonCa). In addition to the 40 genes and transcripts previously shown to be predictive for developing UC-Ca in our microarray studies, 149 new genes, reported to be important in carcinogenesis, were selected for low density array (LDA) analysis. The expression of a total of 189 genes was examined by RT-PCR in nonneoplastic rectal mucosa.

RESULTS

We identified 20 genes showing differential expression in UC-Ca and UC-NonCa patients, including cancer-related genes such as CYP27B1, RUNX3, SAMSN1, EDIL3, NOL3, CXCL9, ITGB2, and LYN. Using these 20 genes, we were able to build a predictive model that distinguished patients with and without UC-Ca with a high accuracy rate of 83% and a negative predictive value of 100%.

CONCLUSION

This predictive model suggests that it is possible to identify UC patients at a high risk of developing cancer. These results have important implications for improving the efficacy of surveillance by colonoscopy and suggest directions for future research into the molecular mechanisms of UC-associated cancer.

Phase I study of biweekly intravenous paclitaxel plus intraperitoneal cisplatin and paclitaxel for gastric cancer with peritoneal metastasis

OBJECTIVES

A phase I study of biweekly intravenous (IV) paclitaxel (PTX) plus intraperitoneal (IP) cisplatin (CDDP) and PTX was performed to determine the maximum tolerated dose (MTD) and recommended dose (RD) in gastric cancer patients.

METHODS

Nine gastric cancer patients with peritoneal metastasis were enrolled. PTX was administered intravenously at a dose of 100 mg/m(2) and intraperitoneally with an initial dose of 20 mg/m(2) (level 1), stepped up to 30 or 40 mg/m(2) depending on observed toxicity. CDDP was administered intraperitoneally at a dose of 30 mg/m(2) over 24 h. PTX and CDDP were administered on days 1 and 15 in 4-week cycles.

RESULTS

The MTD was determined to be dose level 1, as 2 of 3 patients experienced dose-limiting toxicities (DLTs), grade 4 leukopenia and grade 3 vomiting. Therefore, the doses of IV PTX, IP CDDP and IP PTX were reduced to 80, 25 and 20 mg/m(2), respectively (level 0). Consequently, the RD was determined to be dose level 0, as only 1 of 6 patients experienced DLT, grade 3 nausea.

CONCLUSIONS

Combination chemotherapy of IV PTX plus IP CDDP and PTX was shown to be a safe regimen that should be further explored in clinical trials.

Short-term exposure to a 1439-MHz TDMA signal exerts no estrogenic effect in rats

The aim of this study was to elucidate the possible effects of short-term exposure to a 1439-MHz electromagnetic field (EMF) employing time division multiple access (TDMA), which is the basis of the Japanese Personal Digital Cellular system, on estrogenic activity in rats. Sixty-four ovariectomized female Sprague-Dawley rats were divided into four groups: EMF exposure (EM), sham exposure, cage control, and 17 beta-estradiol injected (E2). The EM group was exposed, for 4 h per day on three consecutive days, to the 1439-MHz TDMA signal that produced 5.5-6.1 and 0.88-0.99 W/kg average specific absorption rates in the brain and the whole body, respectively. The uterine wet mass and serum estradiol level significantly increased in the E2 group, while there were no differences among the other three groups. Although negative effects of long-term EMF exposure must be thoroughly investigated before a final conclusion can be reached, our results do not support the assumption that the high frequency EMF used in cellular phones exerts estrogenic activity.

Circulating lymphocyte is an important determinant of the effectiveness of preoperative radiotherapy in advanced rectal cancer

Background

Although preoperative radiotherapy (RT) is widely used as the initial treatment for locally advanced rectal cancer (RC) in the neoadjuvant setting, factors determining clinical response have not been adequately defined. In order to find other factors possibly related with radiosensitivity, we evaluated the relationships between circulating blood cell counts and RT effects.

Methods

In 179 cases with advanced RC, we retrospectively examined hemoglobin (Hb) levels and counts of white blood cells (WBC), platelets and WBC subsets before and after RT and investigated their associations with the complete response (CR) rate together with other clinicopathological factors.

Results

The ratio of lymphocytes in WBC taken before RT was significantly greater in 15 CR cases as compared with those in non-CR cases. Patients with high lymphocyte percentages (25.7%) showed better outcome than the counterparts. Conversely, the ratio of neutrophiles was reduced in CR cases. The lymphocyte ratio showed an independent association with CR with multivariate analysis, and tended to be maintained at relatively high levels in CR cases.

Conclusions

In RC patients, peripheral blood lymphocytes have a significant impact on the CR rate in response to RT. Lymphocyte-mediated immune reactions are supposed to have positive roles on clinical response in radiotherapy for RC.

Loss of sympathetic nerve fibers around intratumoral arterioles reflects malignant potential of gastric cancer

BACKGROUND

The role and clinical significance of the alteration of sympathetic nerve fibers (SNF) was assessed in gastric cancer. Loss of nerve fibers in malignant tumors has previously been described; however, how dysfunction of the nervous system is involved in cancer progression has not been clarified in clinical studies.

MATERIALS AND METHODS

The distribution of SNF was examined in 82 surgically resected gastric cancer specimens with immunohistochemical staining of tyrosine hydroxylase (TH), and the association with clinicopathological findings as well as the clinical outcome of the patients was retrospectively evaluated.

RESULTS

Arterioles in the normal gastric wall were totally covered with SNF, while the immunoreactivity to TH was markedly reduced around arterioles in cancer tissue. The degree of loss of SNF was significantly correlated with the depth of invasion (P < .0001) and lymph node metastasis (P < .0001) as well as microvessel density (MVD) (P = .0043). Moreover, patients who had tumors with marked loss of SNF showed a markedly worse clinical outcome, with an independent association by multivariate analysis.

CONCLUSIONS

Loss of periarteriolar SNF is associated with aggressive phenotype of gastric cancer possibly through enhanced angiogenesis and thus could be a useful marker to predict the clinical outcome.

Analysis of pO2 in malignant ascites of patients with peritoneal dissemination of gastric cancer

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Background: Peritoneal metastasis is considered to develop from carcinoma cells detached from the serosal surface of the primary site and dispersed in the peritoneal cavity. And oxygen is one of the most important environmental factors for tumor development. To investigate the oxygenation condition in the abdominal cavity, that is largely unknown, we collected ascitic fluid from patients with peritoneal dissemination of gastric cancer and measured pO2 of it.

Methods: In 19 patients with peritoneal dissemination of gastric cancer, who had a considerable amount of ascites and was receiving systemic and/or intraperitoneal chemotherapy, ascitic fluid was collected at the bedside in room air, and its pH, pCO2 and pO2 were measured using a blood gas analyzer immediately.

Results: In 19 patients, pH of malignant ascites was significantly lower than that of arterial blood (7.39 ± 0.069 vs 7.44 ± 0.025 mmHg, p < 0.05). pCO2 tended to be higher in ascites than in arterial blood. Unexpectedly, pO2 in malignant ascites showed relatively high values (85.47 ± 23.31 mmHg), which were mostly the same as that of arterial blood (97.19 ± 10.40 mmHg, p = 0.149), and appeared to be higher than that in solid tumor tissue.

Conclusions: Malignant ascites in gastric cancer patients showed an unexpectedly high oxygen tension, which was almost the same as that of arterial blood. The hyperpermeability condition may enable efficient oxygen delivery to peritoneal fluid via the microvessels lining the peritoneal cavity. Since the oxygen level critically affects the sensitivity of tumor cells to chemotherapeutic agents through metabolic transformation, aerobic conditions may be beneficial for the progression of peritoneal metastasis and also clinically important in considering the efficacy of chemotherapy.

No significant financial relationships to disclose.

Phase I study of biweekly intravenous paclitaxel plus intraperitoneal cisplatin and paclitaxel for gastric cancer with peritoneal metastasis

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Background: Intraperitoneal (IP) chemotherapy is promising for the treatment of gastric cancer with peritoneal metastasis. We previously verified the safety and efficacy of IP paclitaxel (PTX) combined with S-1 and intravenous (IV) PTX in phase I and phase II studies (Oncology. 2009; Ann Oncol. 2010). Secondly, we developed a new IP-containing chemotherapy regimen, IV PTX plus IP cisplatin (CDDP) and PTX, for patients who have failed S-1-based chemotherapy. We performed a phase I study to determine the maximum-tolerated dose (MTD) and recommended dose (RD) in gastric cancer patients.

Methods: A total of 9 gastric cancer patients were enrolled who had shown progression of peritoneal metastasis after S-1-based chemotherapy. PTX was administered intravenously at a dose of 100 mg/m2 and intraperitoneally over 1 hour with an initial dose of 20 mg/m2 (level 1), stepped up to 30 or 40 mg/m2 depending on observed toxicity. CDDP was subsequently administered intraperitoneally at a dose of 30 mg/m2 over 24 hours after PTX infusion. PTX and CDDP were administered on days 1 and 15 in 4-week cycles.

Results: At dose level 1, dose-limiting toxicities (DLTs) were observed in 2 of 3 patients. One patient experienced grade 4 leukopenia, and the other grade 3 vomiting. Because of higher toxicities than anticipated, the initial dose-escalation schedule was abandoned, and the doses of IV PTX and IP CDDP were reduced to 80 mg/m2 and 25 mg/m2, respectively, while keeping the dose of IP PTX at 20 mg/m2 (level 0). At dose level 0, one of the first 3 patients experienced grade 3 nausea, and an additional 3 patients experienced no DLTs. Consequently, the MTD and RD were determined to be dose level 1 and dose level 0, respectively. No patients experienced complications related to the peritoneal access device or IP infusion.

Conclusions: Combination chemotherapy of IV PTX plus IP CDDP and PTX was shown to be a safe regimen that should be further explored in clinical trials.

No significant financial relationships to disclose.

RUNX3 copy number predicts the development of UC-associated colorectal cancer

RUNX3 is a tumour suppressor gene that plays an important role in the development of various cancers. The present study aimed to compare RUNX3 mRNA expression levels and DNA copy numbers in the non-neoplastic rectal mucosa between ulcerative colitis (UC) patients with and without UC-associated colorectal cancer (UC-Ca). We further aimed to build a predictive model of the development of UC-Ca based on the RUNX3 DNA copy number. RUNX3 mRNA expression levels were quantified by RT-PCR. The hypermethylation and DNA copy number of RUNX3 were also determined. Thirty-five UC patients were examined, 17 of whom had UC-Ca (UC-Ca group) and 18 who did not (UC-NonCa group). The UC-Ca group had significantly lower mRUNX3 expression levels and smaller DNA copy numbers than the UC-NonCa group (p=0.04, p=0.0016, respectively). RUNX3 expression levels correlated with DNA copy numbers. Classification of the UC-Ca and UC-NonCa group based on DNA copy number gave an accuracy of 82.9%. RUNX3 expression levels in the non-neoplastic rectal mucosa was significantly decreased in the UC-Ca group and it is suggested that this was attributable to the decrease in RUNX3 DNA copy number. The present predictive model may be useful in the selection of high risk UC-Ca patients and to improve the efficacy of surveillance colonoscopy. The present study suggests that RUNX3 might play an important role in the development of UC-Ca.

Enhanced neovascular formation in a novel hydrogel matrix consisting of citric Acid and collagen

BACKGROUND

Three-dimensional regenerative tissue with large bulk generally requires blood perfusion through a vascular network to maintain its viability, and one promising approach is induction of neovascular growth from the recipient bed into the tissue. To induce ingrowth of a vascular network, it is necessary to furnish the regenerative tissue with a scaffold structure for neovasculature and a delivery system for an angiogenic growth factor. As such a scaffold structure, the present study created novel hydrogel materials by chemically cross-linking alkali-treated collagen (AlCol) with trisuccinimidyl citrate (TSC).

MATERIALS AND METHODS

Many prototypes, consisting of several concentrations of TSC and AlCol, were implanted into the subfascial space of the rat rectus muscle, and 7 days later, the implanted materials were excised for histological analysis. Cross-sections were stained and neovascular development in the materials was evaluated by measuring vessel density, length and number of joints and branches.

RESULTS

Significant ingrowth of vascularized granulation was observed in some materials, which surpassed the angiogenic ability of Matrigel(TM). Further, combination with basic fibroblast growth factor (bFGF) significantly increased the vascular formation in these gels.

CONCLUSIONS

The TSC-AlCol gel functioned as a favorable scaffold for neovascular formation and also as a reservoir for controlled delivery of bFGF.

Prognostic significance of response to preoperative radiotherapy, lymph node metastasis, and CEA level in patients undergoing total mesorectal excision of rectal cancer

PURPOSE

The aim of this study was to investigate the prognostic significance of the response of primary rectal lesions to preoperative radiotherapy, pathological nodal status, and carcinoembryonic antigen (CEA) levels before and after radiotherapy in rectal cancer patients treated with a total mesorectal excision.

METHODS

We investigated the prognostic significance of the clinical and pathological factors in 97 patients treated with preoperative radiotherapy (50-50.4 Gy over 5-6 weeks) followed by curative resections.

RESULTS

A high CEA level (>5 ng/mL) after radiotherapy (hazard ratio, 2.849; 95% confidence interval, 1.061-7.651; p = 0.0377) and pathological lymph node metastasis (hazard ratio, 0.350; 95% confidence interval, 0.154-0.797; p = 0.0124) were independently associated with postoperative recurrence. Although the CEA level before radiotherapy was associated with disease-free survival in a univariate analysis, it lost its statistical significance in a multivariate analysis. The response of the primary rectal lesions, evaluated pathologically by T stage and the degree of regression, was not associated with disease-free survival. In patients without lymph node metastasis, the 5-year disease-free survival of those with a high CEA level after radiotherapy was significantly worse than those with low CEA after radiotherapy (61.6% vs. 89.0%, respectively, p = 0.0234).

CONCLUSIONS

Pathological lymph node metastasis and a high CEA level after radiotherapy were independent predictors of a poor outcome in rectal cancer patients treated with preoperative radiotherapy. The CEA level after radiotherapy was capable of discriminating patients with a high risk of recurrence among pathologically node-negative patients.

Spatial distribution of intraperitoneally administrated paclitaxel nanoparticles solubilized with poly (2-methacryloxyethyl phosphorylcholine-co n-butyl methacrylate) in peritoneal metastatic nodules

Intraperitoneal (i.p.) administration of paclitaxel nanoparticles (PTX-30W) prepared by solubulization with the amphiphilic copolymer of 2-methacryloxyethyl phosphorylcholine and n-butyl methacrylate can efficiently suppress the growth of peritoneal metastasis. In this study, we characterized the drug distribution of i.p. injected PTX-30W in peritoneal tumor and liver in a mouse model using MKN45, human gastric cancer cells. Oregon green-conjugated PTX-30W showed perivascular accumulation in MKN45 tumor in the peritoneum at 24 h after intravenous (i.v.) injection; however, the amount of PTX in tumor was markedly less than that in liver. In contrast, a larger amount of PTX accumulated in the peripheral area of disseminated nodules at 1 h after i.p. injection and the area gradually enlarged. The depth of PTX infiltration reached 1 mm from the tumor surface at 48 h after i.p. injection, and the fluorescence intensity was markedly greater than that in liver. Interestingly, i.p. injected PTX preferentially accumulated in relatively hypovascular areas, and many tumor cells in the vicinity of PTX accumulation showed apoptosis. This unique accumulation pattern and lesser washout in hypovascular areas are thought to be attributable to the superior penetrating activity of PTX-30W, and thus, PTX-30W is considered to be highly suitable for i.p. chemotherapy for peritoneal dissemination.

Catechin inhibits adhesion and migration of peripheral blood B cells by blocking CD11b

CONTEXT

Previously, we demonstrated that CD11b is expressed on peripheral blood memory B cells, and it plays an important role in the migration of B cells. And epigallocatechin gallate (EGCG), a bioactive component of green tea, by binding to CD11b, expressed on CD8(+) cytotoxic T cells, inhibited their migratory ability, one possible mechanism of the antiallergic activity of EGCG.

OBJECTIVE

Here, we investigated whether EGCG also affected CD11b expressed on B cells, similar to cytotoxic T cells.

MATERIALS AND METHODS

Isolated peripheral blood CD19(+) B cells were treated with EGCG and the change in the expression of CD11b was analyzed using flow cytometry. The effects of EGCG on the ability of B cells to adhere to and to transmigrate through the endothelial cell layer were evaluated using the transwell assay.

RESULTS

EGCG significantly suppressed the apparent expression of CD11b on B cells, in the flow-cytometric analysis, and this apparent suppression was speculated to be dependent on the competitive binding of EGCG to CD11b. EGCG also significantly suppressed CD11b-mediated migration and adhesion of B cells to endothelial cells.

DISCUSSION AND CONCLUSION

EGCG has a strong suppressive activity on the adhesive and migratory abilities of peripheral blood B cells. This suppressive activity was mediated by the binding of EGCG to CD11b on B cells, and the consequent suppression of B-cell extravasation to the extravascular space. Because B cell plays an important role in the humoral immunity, EGCG could be a promising drug for the prevention and/or treatment of allergic and/or autoimmune diseases.

Analysis of pO(2) in Malignant Ascites of Patients with Peritoneal Dissemination of Gastric Cancer

Objective

Oxygen is one of the most important environmental factors for tumor development. In this study, we examined pO₂ in malignant ascites in patients with peritoneal carcinomatosis.

Methods

In 21 patients with peritoneal dissemination of gastric cancer, ascitic fluid was collected and its pH, pCO₂ and pO₂ were determined using a blood gas analyzer.

Results

In 21 patients, pH of malignant ascites was significantly lower than that of arterial blood (7.39 ± 0.07, 7.44 ± 0.02, p < 0.05). Accordingly, pCO₂ tended to be higher in ascites than in arterial blood. Unexpectedly, pO₂ in malignant ascites showed relatively high values (90.4 ± 27.72 mm Hg), which were mostly the same as those of arterial blood (97.09 ± 10.33 mm Hg, p = 0.858). Even in 19 patients whose samples were collected at bedside in room air, pO₂ of malignant ascites was 85.94 ± 23.94 mm Hg, which was patently higher than that in venous blood or in solid tumor tissues.

Conclusion

Since the oxygen level critically affects the sensitivity of tumor cells to chemotherapeutic agents through metabolic transformation, the oxygenic condition in the peritoneal cavity may be beneficial for the progression of peritoneal metastasis, and also clinically important in considering the efficacy of chemotherapy.

Adiponectin receptors are downregulated in human gastric cancer

BACKGROUND

Adiponectin has been shown to have suppressive effects on tumor development, but the expression of adiponectin receptors in tumor tissue has not been fully elucidated. The purpose of this study was to quantitatively evaluate the expression of two adiponectin receptors, AdipoR1 and AdipoR2, in gastric cancer tissue.

METHODS

The mRNA levels of AdipoR1 and AdipoR2 were evaluated by quantitative reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical staining in 67 gastric cancer tissues and their normal counterparts. In addition, the effects of cytokines on AdipoR1 and AdipoR2 expression in cultured gastric cancer cells were examined.

RESULTS

As compared to findings in the normal counterparts, AdipoR1 mRNA expression, standardized by β-actin mRNA, tended to be lower (cancer 0.488 ± 0.039, normal 0.955 ± 0.281, p = 0.0726) and AdipoR2 expression was significantly lower (0.818 ± 0.081, 1.500 ± 0.222, p = 0.0035) in gastric cancer tissue. Immunohistochemical examination showed the same tendency for AdipoR1 and AdipoR2 expression in epithelial cells. Moreover, AdipoR2 was strongly expressed in interstitial cells. However, the expression levels of these receptors did not show a strong correlation with various pathological factors. An in vitro experiment using two gastric cancer cell lines, MKN-74 and NUGC-3, showed that the expression levels of AdipoR1 and AdipoR2 were significantly decreased by transforming growth factor (TGF)-β in a dose-dependent manner.

CONCLUSIONS

Two major adiponectin receptors were decreased in gastric cancer as compared to findings in normal gastric epithelium. TGF-β may be involved in this receptor downregulation. This downregulation may be an ideal strategy for cancer cells to escape the antiproliferative effects of adiponectin in the initial phase of tumor development.

The inhibition of autophagy potentiates anti-angiogenic effects of sulforaphane by inducing apoptosis

BACKGROUND

Sulforaphane (SUL), a kind of isothiocyanate, has recently been focused due to its strong pro-apoptotic effect on cancer cells as well as tumor vascular endothelial cells (ECs). And recently, we demonstrated the induction of autophagy by colon cancer cells as a protective mechanism against SUL. In the present study, we aimed to investigate the possible role of autophagy induction by ECs as a defense mechanism against SUL.

METHODS

Human umbilical vein endothelial cells (HUVECs) were used as the in vitro model of angiogenic ECs. The induction of autophagy was evaluated by the detection of acidic vesicular organelles (AVOs) by flow-cytometry, after the staining with acridine orange, as well as the detection of light chain 3(LC3) by Western blot. Finally, the functional implication of autophagy inhibition and SUL treatment in ECs was investigated by their ability to form vascular-like structures on Matrigel.

RESULTS

Treatment of HUVECs with relatively low concentrations of SUL for 16 h resulted in the evident formation of AVOs and the recruitment of LC3 to autophagosomes, the pathognomonic features of autophagy. Co-treatment of cells with the specific autophagy inhibitor (3-methyladenine) potentiated the proapoptotic effect of SUL. And inhibition of autophagy potentiated the inhibitory effect of SUL on the ability of ECs to form capillary-like structures.

CONCLUSION

Similar to cancer cells, ECs induced autophagy in response to the pro-apoptotic agent, SUL, and the inhibition of autophagy potentiated the pro-apoptotic effect. These findings open premises for the use of autophagy inhibitors in combination with anti-angiogenic agents.

Chloroquine potentiates the anti-cancer effect of 5-fluorouracil on colon cancer cells

Background

Chloroquine (CQ), the worldwide used anti-malarial drug, has recently being focused as a potential anti-cancer agent as well as a chemosensitizer when used in combination with anti-cancer drugs. It has been shown to inhibit cell growth and/or to induce cell death in various types of cancer. 5-Fluorouracil (5-FU) is the chemotherapeutic agent of first choice in colorectal cancer, but in most cases, resistance to 5-FU develops through various mechanisms. Here, we focused on the combination of CQ as a mechanism to potentiate the inhibitory effect of 5-FU on human colon cancer cells.

Methods

HT-29 cells were treated with CQ and/or 5-FU, and their proliferative ability, apoptosis and autophagy induction effects, and the affection of the cell cycle were evaluated. The proliferative ability of HT-29 was analyzed by the MTS assay. Apoptosis was quantified by flow-cytometry after double-staining of the cells with AnnexinV/PI. The cell cycle was evaluated by flow-cytometry after staining of cells with PI. Autophagy was quantified by flow-cytometry and Western blot analysis. Finally, to evaluate the fate of the cells treated with CQ and/or 5-FU, the colony formation assay was performed.

Results

5-FU inhibited the proliferative activity of HT-29 cells, which was mostly dependent on the arrest of the cells to the G0/G1-phase but also partially on apoptosis induction, and the effect was potentiated by CQ pre-treatment. The potentiation of the inhibitory effect of 5-FU by CQ was dependent on the increase of p21^Cip1 and p27^Kip1 and the decrease of CDK2. Since CQ is reported to inhibit autophagy, the catabolic process necessary for cell survival under conditions of cell starvation or stress, which is induced by cancer cells as a protective mechanism against chemotherapeutic agents, we also analyzed the induction of autophagy in HT-29. HT-29 induced autophagy in response to 5-FU, and CQ inhibited this induction, a possible mechanism of the potentiation of the anti-cancer effect of 5-FU.

Conclusion

Our findings suggest that the combination therapy with CQ should be a novel therapeutic modality to improve efficacy of 5-FU-based chemotherapy, possibly by inhibiting autophagy-dependent resistance to chemotherapy.

Circulating lymphocyte number has a positive association with tumor response in neoadjuvant chemoradiotherapy for advanced rectal cancer

Although neoadjuvant chemoradiotherapy (CRT) is the standard treatment for advanced rectal cancer (RC), markers to predict the treatment response have not been fully established. In 73 patients with advanced RC who underwent CRT in a neoadjuvant setting, we retrospectively examined the associations between the clinical effects of CRT and blood cell counts before and after CRT. Clinical or pathological complete response (CR) was observed in 10 (14%) cases. The CR rate correlated significantly with the size and the circumferential extent of the tumor. Hemoglobin level, white blood cell (WBC) count and platelet count before CRT did not show a significant difference between CR and non-CR cases. Interestingly, however, lymphocyte ratio in WBC was significantly higher (p = 0.020), while neutrophil ratio tended to be lower (p = 0.099), in CR cases, which was shown to be an independent association by multivariate analysis. When all the blood data obtained in the entire treatment period were evaluated, circulating lymphocyte count was most markedly decreased in the CRT period and gradually recovered by the time of surgery, while the numbers of neutrophils and monocytes were comparatively stable. Moreover, the lymphocyte percentage in samples obtained from CR patients was maintained at a relatively higher level than that from non-CR patients. Since tumor shrinkage is known to be dependent not only on the characteristics of tumor cells but also on various host conditions, our data raise the possibility that a lymphocyte-mediated immune reaction may have a positive role in achieving complete eradication of tumor cells. Maintenance of circulating lymphocyte number may improve the response to CRT in rectal cancer.

Treatment of colorectal carcinoids: A new paradigm

It is often difficult to evaluate the grade of malignancy and choose an appropriate treatment for colorectal carcinoids in clinical settings. Although tumor size and depth of invasion are evidently not enough to stratify the risk of this rare tumor, the present guidelines or staging systems do not mention other clinicopathological variables. Recent studies, however, have shed light on the impact of lymphovascular invasion on the outcome of colorectal carcinoids. It has been revealed that the presence of lymphovascular invasion was among the strongest risk factors for metastasis along with tumor size and depth of invasion. Furthermore, tumors smaller than 1 cm, within submucosal invasion and without lymphovascular invasion, carry minimal risk for metastasis with 100% 5-year survival in the studies from Japan as well as from the USA. This would suggest that these tumors could be curatively treated by endoscopic resection or transanal local excision. On the other hand, colorectal carcinoids with either lymphovascular invasion or tumor size larger than 1 cm carry the risk for metastasis equivalent to adenocarcinomas. Therefore, it should be emphasized that histological examination of lymphovascular invasion is mandatory in the specimens obtained by endoscopic resection or transanal local excision, as this would provide useful information for determining the need for additional radical surgery with regional lymph node dissection. Although the present guidelines or TNM staging system do not mention the impact of lymphovascular invasion, this would be among the next promising targets in order to establish better guidelines and staging systems, particularly in early-stage colorectal carcinoids.

[Three cases of metastatic breast cancer effectively treated with S-1 therapy]

We experienced 3 cases of recurrent breast cancer treated with S-1 therapy, delaying tumor progression and improving their quality of life (QOL). All the patients had been previously treated with both anthracyclines and/or taxanes prior to S-1 chemotherapy. All patients almost completed the full dose through the whole course of treatment, and the drug showed good tolerability. Long-term(more than 12 weeks)therapeutic efficacy and the patients' QOL have been maintained for all patients. No major side effects were seen. It is thought that less toxicity enabled patient 3 to undergo long-term therapy. It is especially important that one patient had therapeutic efficacy and QOL improvement from treatment with S-1 and aromatase inhibitor for over 3 years, after being treated with anthracyclines, taxanes and vinorelbine. We conclude that S-1 is effective and well tolerated in patients with metastatic breast cancer, and will accommodate a long-time progression with respect to efficacy and maintaining the patients' QOL. Further evaluation of S-1 is necessary to elucidate its clinical role in breast cancer treatment.

Preoperative chemoradiation and extended pelvic lymphadenectomy for rectal cancer: Two distinct principles

Extended pelvic lymphadenectomy (EPL) with total mesorectal excision (TME) has been reported to provide oncological benefit in lower rectal cancer in Japan. In Western countries EPL is not widely accepted because of frequent morbidity but instead preoperative chemoradiation (CRT) followed by TME has been established as a standard treatment for decreasing local recurrence. Recently, several studies have focused on the comparison between these two distinct therapeutic approaches in Western countries and Japan. A study comparing Dutch trial data and Japanese data revealed that EPL and RT are almost equivalent in decreasing local recurrence in lower rectal cancer as compared with TME alone. Considering that almost 45% survival can be achieved by EPL even in the presence of metastatic lateral lymph nodes (LLNs), EPL performed by experienced surgeons definitely contributes to decrease local recurrence. On the other hand, a randomized controlled trial in Japan that compared EPL with conventional TME following preoperative RT revealed that EPL is associated with a higher frequency of sexual and urinary dysfunction without oncological benefits in the presence of preoperative RT. On this point, preoperative CRT followed by conventional TME without EPL would be a better therapeutic approach in patients without evident metastatic LLNs. For future treatment, it would be desirable to have a narrower indication for EPL using full advantage of recent improvement in image diagnosis. Although objective comparison of these two principles between Japan and the West is difficult due to differences in patient groups, further studies would lead to the next great step towards future improvement in treating lower rectal cancer.

Abstract 3908: Id1/Id3 Knockdown increases Chemosensitivity of Colorectal Cancer

Objective: The inhibitor of DNA binding/differentiation (Id) proteins belong to the helix-loop-helix transcriptional regulatory factors, and play important roles in tumor development. Recently, overexpression of Id-1 has been associated with more aggressive and metastatic cancers in various cancer types, as well as implicated in resistance to chemotherapy, and thus, its down-regulation has been shown to lead to increased chemotherapy-induced apoptosis. Previously, we have demonstrated that simultaneous targeting of Id1 and Id3 inhibited proliferation, migration, adhesion, and metastatic growth of colorectal cancers. In the present study, we aimed to evaluate the role of Id in chemosensitivity of colorectal cancer cells, and for this purpose, human colon cancer cells with downregulated expression of Id1/Id3 were treated with oxaliplatin, and the changes in the sensitivity to chemotherapy as well as the mechanisms underlying it were investigated.

Methods: Id1 and Id3 were stably and simultaneously knockdown in human colorectal cancer cell line HT29 by means of RNA interference. Both Id1 and Id3 were double-knockdown since they are known to functionally compensate each other, and the downregulation of either is not enough for the inhibition of their effects. Parental HT29 cells and the empty vector (mock) transfectants were used as control. Oxaliplatin, one component of FOLFOX6, which is one of the standard treatment protocols for colorectal cancer, was chosen as the chemotherapeutic agent. The chemosensitivity was investigated as follows: the proliferative activity was analyzed by the MTS assay, the induction of apoptosis, by the flow-cytometry after double-staining of the cells with AnnexinV/PI. Induction of autophagy was investigated by flow-cytometry after staining of the cells with acridine orange for the detection of AVOs. The changes of the cell cycle were investigated by flow-cytometry after staining of the cells with propidium iodide (PI).

Results: Id double-knockdown resulted in increased chemosensitivity to oxaliplatin, as observed by the reduced proliferative ability compared with parental and mock cells. And the reduced proliferative activity was associated with the arrest of cell to the G2-M phase of the cell cycle, and the increased cell apoptosis. The chemosensitivity of Id double-knockdown cells seemed to be associated with decreased ability to induce autophagy in response to the chemotherapeutic agent.

Conclusions: Id1, 3 double-knockdown resulted in increased chemosensitivity of colorectal cancer cells to oxaliplatin, dependent on the cell cycle arrest and apoptosis induction. And the decreased ability to induce autophagy seemed to be a mechanism responsible for this effect. From these results, we concluded that Id proteins play an important role in the chemoresistance of colorectal cancer, and downregulation of Id should be a promising strategy to improve chemosensitivity of Id expressing cancers.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3908.

Abstract 3367: CD133- colorectal cancer cells have higher chemo-resistance ability than CD133+cells

(Background and purpose)

Recently, many reports suggest that a limited population of tumor cells have the capability of tumorigenesis. These cells, called cancer stem cells (CSCs) or tumor initiating cells, are suggested to be involved in tumor recurrence after long interval as well as in chemo-resistance. There are several CSC markers, including CD44 and CD133. CD133, originally a hematopoietic stem cell marker, was identified also as a stem cell marker for various tumor types. In the present study, we aimed to compare the characteristics of CD133+ and CD133- colorectal cancer cells to test the hypothesis of CD133 being a potential specific marker for colorectal CSCs.

(Methods)

Using auto magnetic activated cell sorting (MACS), the human colon cancer cell line LoVo was separated into CD133+ and CD133- cell subpopulations, and their sensitivity to 5-FU, specially focusing on apoptosis and autophagy inductions were investigated. The sensitivity of CD133+ and - cells to 5-FU was tested by the MTS assay. And the induction of apoptosis was analyzed by flow-cytometry, after double-staining with annexin V-FITC/PI. The expression of β1-integrins was analyzed by flow-cytometry, and their ability to bind extracellular matrix (ECM) proteins was evaluated by the adhesion assay. Induction of autophagy was investigated by flow-cytometry after staining with acridine orange, and by Western blot for the expressions of the LC3 protein.

(Results)

After MACS isolation, CD133+ and CD133- cells were separately cultured. The purity of the obtained cell populations was more than 98%. After several days of culture, the proportion of CD133+ and CD133- cells was not changed in both cell populations during about a month. CD133- cells showed higher resistance to 5-FU than CD133+cells, in vitro. It was dependent on the higher induction of apoptosis in CD133+ cells. CD133+ cells had lower expression of β1-integrins compared with CD133- cells, and consequently, their ability to adhere ECM proteins was weaker. Additionally, AVOS formation was weaker in CD133+ cells, as well as the expression of LC3-II.

(Discussion)

CD133+ cells were more sensitive to 5-FU than CD133- cells, and it may be dependent on the higher ability of CD133- cells to induce autophagy in response to 5-FU. Additionally, CD133- cells had higher ability to adhere to ECM proteins through β1-integrins, and it may be another mechanism of chemo-resistance. Taking these results, higher ability to adhere to ECM proteins may confer resistance to 5-FU by improving the ability of cells to induce autophagy as a cell survival mechanism. Presently, there is controversy regarding CD133 as a specific marker of CSCs, but from our results, CD133- cells are more resistant to chemotherapy, one typical feature of CSCs. Therefore, we concluded that CD133 may not be used as a single CSC marker, but on the other hand, it may be a potential marker for the prediction of chemo-sensitivity in colorectal cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3367.

Abstract 4841: Inhibition of autophagy potentiates the anti-angiogenic effects of sulforaphane

Background: Sulforaphane (SUL), a kind of isothiocyanate, has been reported to exert strong inhibitory effects on various cancer cells by inducing apoptosis and/or cell cycle arrest. Recently autophagy induction by cancer cells has been focused as a defense mechanism against various proapoptotic agents, which may result in resistance to cancer therapy. Therefore, inhibition of autophagy in cancer cells may be a novel strategy in cancer therapy.

Tumor cells depend on angiogenesis for their growth and metastasis and, therefore, anti-angiogenic therapy is a promising anti-cancer strategy.

In the present study, we aimed to investigate the anti-angiogenic effect of SUL, and the possible induction of autophagy by tumor vascular endothelial cells as a defense mechanism against SUL-induced apoptosis. Additionally, we investigated the role of specific autophagy inhibitor in potentiating the proapoptotic effect of SUL. For these purposes, the human umbilical vein endothelial cells (HUVECs) were used as the in vitro model of tumor endothelium.

Methods: HUVECs were isolated from umbilical cords, obtained from normal pregnants at the delivery, from whom informed consent was obtained. Cells were treated with SUL at different concentrations, and their proliferative activity was assessed by the MTS assay. Apoptosis was investigated by flow-cytometry after double-staining with FITC-conjugated Annexin-V and propidium iodine. The formation of acidic vesicular organelles (AVOs) was detected by fluorescence microscopy and flow-cytometry following staining with acridine orange. Detection of light chain 3 (LC3) levels was investigated by Western blot. Localizations of LC3 and cytochrome c were analyzed by immunocytochemistry. Finally, the vascular-like structure formation on Matrigel was investigated. The role of the specific autophagy inhibitor (3-methyladenine (3-MA)) in potentiating the effects of SUL was similarly investigated.

Results: The proapoptotic effect was observed by treatment of cells with relatively high concentrations of SUL for long periods of time. At 16 hour-treatment with lower concentrations of SUL, the features of autophagy, were observed in HUVECs. Treatment of cells with 3-MA potentiated the proapoptotic effect of SUL, which was dependent on the activation of caspases and the release of cytochrome c to the cytosol. SUL dose-dependently inhibited the tube-like formation by HUVECs on Matrigel, an important event in the process of angiogenesis, and treatment of 3-MA potentiated this effect.

Conclusion: The present results demonstrate the induction of autophagy in endothelial cells as a protective reaction against the proapoptotic effect of SUL, and consequently, the potentiation of the proapoptotic effect by the inhibition of autophagy. These findings open premises for the use of autophagy inhibitors in combination with chemotherapeutic agents for the anti-angiogenic agents.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4841.

Abstract 422: (-)-Epigallocatechin-3-gallate inhibits the metastatic potential of colon cancer

Objective: Green tea catechins have been shown to be potential chemopreventive agents against various types of cancer Among them, Epigallocatechin-3-gallate (EGCG), which accounts for almost 50% of the total catechin content in green tea extract, has been focused due to its potent antioxidant effects. EGCG inhibits enzyme activities and signal transduction pathways, resulting in the suppression of cell proliferation and enhancement of apoptosis. Also, it is reported to inhibit cell invasion, angiogenesis and metastasis. However, the exact mechanisms of the anti-proliferative/anti-metastatic activities of EGCG are not completely understood. In the present study, we aimed to investigate the mechanisms of the inhibitory effect of EGCG on colon cancer cells, especially focusing on cell adhesion.

Methods: HT-29 human colon cancer cells were used. The effect of EGCG on the proliferative activity was investigated by the MTS assay. The expression of integrins was analyzed by flow-cytometry. Apoptosis induction was analyzed by flow-cytometry after double-staining of cells with AnnexinV/PI. The ability of cells to adhere to extracellular matrix (ECM) proteins was tested by the adhesion assay on fibronectin, collagen and laminin.

Results: EGCG dose-dependently decreased the ability of HT-29 cells to proliferate on and adhere to ECM proteins. The amount of cell surface integrins, however, was not affected by EGCG. Additionally, EGCG treatment did not induce apoptosis of HT-29 cells. Therefore, the affection of the proliferative activity by EGCG was attributed to anoikis.

Conclusions: EGCG dose-dependently decreased the ability of colon cancer cells to proliferate on and to adhere to ECM proteins. It was not dependent on changes in the expression of β1-integrins, but on the affection of the ability of β1-integrins to bind the ECM proteins. Binding to the ECM proteins is an important event for cancer cells to proliferate, migrate, invade, and form metastatic lesions. Therefore, EGCG, by affecting the ability of colon cancer cells to adhere to ECM proteins, may be a potential agent for the prevention and/or treatment of colon cancer metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 422.

Abstract 1749: The downregulated expression of adiponectin receptors (AdipoR1, R2) in human colorectal cancer

[Background] Adiponectin is 30 kDa adipocytokine hormone secreted by the adipose tissues, which mediates antineoplastic as well as anti-angiogenic effects after binding to its receptors, Adipo-R1 and Adipo-R2, which has been reported to be expressed in colorectal cancer tissue and cell lines. Recent studies have shown decreased levels of adiponectin in sera of patients with various types of cancer, including colorectal. And a recent study demonstrated that adiponectin expression is significantly associated with high histological grade tumors and low microvessel density count in colorectal cancer, suggestive of an anti-angiogenic role for adiponectin in colorectal cancer. However, presently, the expression and function of adiponectin receptors in tumor tissue have not been well characterized. Thus, in the present study, we aimed to study the expression of adiponectin receptors in colorectal cancer tissues, and investigate on their clinicopathological implications.

[Methods] Surgically resected specimens from 48 patients with colorectal cancer, receiving surgical operation in our surgical department in the period between November 2008 and July 2009, were analyzed. The study was approved by the Human Ethics Committee of the University of Tokyo. The messages and protein expressions of AdipoR1 and AdipoR2 were evaluated by real-time RT-PCR and immunohistochemistry, respectively, in cancer tissues and the matched normal counterparts.

[Results] The mean age of the patients was 66.79±11.85 years. The levels of expression of both AdipoR1/AdipoR2, normalized with the internal control (beta-actin), were significantly lower in cancer specimens compared with normal mucosa (0.966±0.392, vs1.366±0.408, p&lt;0.001 and 0.918±0.309, vs1.596±0.459, p&lt;0.001, respectively for AdipoR1 and Adipo R2). The mRNA levels of AdipoR1 and AdipoR2 showed a tendency of decrease in tumors with nodal metastases and the difference was significant with AdipoR2 (p&lt;0.05). Immunohistochemistry with polyclonal Abs showed a consistent reduction in protein expression of both receptors in cancer tissues in comparison with the normal counterparts.

[Conclusion] Both receptors were downregulated in colorectal cancer, as confirmed by the mRNA and the protein expressions, and AdipoR2 seemed to be associated with nodal metastases. This downregulation seems to be associated with poorer prognosis of colorectal cancer, and may be an escape mechanism of cancer cells from the suppressive effects of adiponectin.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1749.