Glen C. Balch

Regulation of Cyclooxygenase-2 Expression by the Translational Silencer TIA-1

The cyclooxygenase-2 (COX-2) enzyme catalyzes the rate-limiting step of prostaglandin formation in inflammatory states, and COX-2 overexpression plays a key role in carcinogenesis. To understand the mechanisms regulating COX-2 expression, we examined its posttranscriptional regulation mediated through the AU-rich element (ARE) within the COX-2 mRNA 3′-untranslated region (3′UTR). RNA binding studies, performed to identify ARE-binding regulatory factors, demonstrated binding of the translational repressor protein TIA-1 to COX-2 mRNA. The significance of TIA-1-mediated regulation of COX-2 expression was observed in TIA-1 null fibroblasts that produced significantly more COX-2 protein than wild-type fibroblasts. However, TIA-1 deficiency did not alter COX-2 transcription or mRNA turnover. Colon cancer cells demonstrated to overexpress COX-2 through increased polysome association with COX-2 mRNA also showed defective TIA-1 binding both in vitro and in vivo. These findings implicate that TIA-1 functions as a translational silencer of COX-2 expression and support the hypothesis that dysregulated RNA-binding of TIA-1 promotes COX-2 expression in neoplasia.

An Essential Mesenchymal Function for miR-143/145 in Intestinal Epithelial Regeneration

Downregulation of the miR-143/145 microRNA (miRNA) cluster has been repeatedly reported in colon cancer and other epithelial tumors. In addition, overexpression of these miRNAs inhibits tumorigenesis, leading to broad consensus that they function as cell-autonomous epithelial tumor suppressors. We generated mice with deletion of miR-143/145 to investigate the functions of these miRNAs in intestinal physiology and disease in vivo. Although intestinal development proceeded normally in the absence of these miRNAs, epithelial regeneration after injury was dramatically impaired. Surprisingly, we found that miR-143/145 are expressed and function exclusively within the mesenchymal compartment of intestine. Defective epithelial regeneration in miR-143/145-deficient mice resulted from the dysfunction of smooth muscle and myofibroblasts and was associated with derepression of the miR-143 target Igfbp5, which impaired IGF signaling after epithelial injury. These results provide important insights into the regulation of epithelial wound healing and argue against a cell-autonomous tumor suppressor role for miR-143/145 in colon cancer.

Lymphatic mapping and sentinel lymphadenectomy after preoperative therapy for stage II and III breast cancer

AbstractBackground: We evaluated the accuracy of sentinel lymph node dissection (SLND) in patients with stage II and III breast cancer who had received preoperative therapy. Methods: A prospective clinical trial evaluated 122 patients who had SLND followed by axillary lymph node dissection. Thirty-two women had stage II or III breast cancer and received preoperative doxorubicin-based chemotherapy or paclitaxel and radiotherapy. Results: A sentinel lymph node (SLN) was identified in 31 (97%) of 32 patients. The SLN predicted the status of the axillary nodes in 30 (97%) of 31 patients. Eighteen (58%) of 31 had metastases in the SLN. Eighteen of 19 patients with axillary metastases had a tumor-positive SLN (sensitivity, 95%; false-negative rate, 5%). Eight (44%) of 18 women with metastases in the SLN also had metastases in 1 or more nonsentinel nodes. Conclusions: In this relatively small study, the accuracy of SLND in women with stage II or III breast cancer treated with preoperative therapy was similar to that achieved in early-stage breast cancer. If these results are confirmed in a larger cohort, it may be feasible to substitute SLND for routine axillary lymph node dissection in this population. This approach could reduce the morbidity of surgical therapy while preserving the accuracy of axillary staging and maintaining regional control in this high-risk population.

Smad3 has a critical role in TGF-β-mediated growth inhibition and apoptosis in colonic epithelial cells

BACKGROUND Smad proteins play a key role in TGF-beta signaling that regulates cell proliferation, differentiation, and apoptosis. Mice deficient in Smad3 develop colonic adenocarcinoma. MATERIALS AND METHODS We developed a Smad3-deficient colonocyte cell line that was used to study TGF-beta-mediated growth inhibition and induction of apoptosis was compared to young adult mouse colonocyte (YAMC) control cells. Growth inhibition was assessed by cell count and ((3)H)-thymidine incorporation assay. Transcriptional response to TGF-beta was measured by transfecting the reporters p3TP-Lux and p(CAGA)(9)-MLP-luc. TGF-beta-induced apoptosis was assessed using ELISA and Hoechst staining. Mediators of cell-cycle arrest and apoptosis were assayed by Western blot. RESULTS Smad3-/- cells were resistant to TGF-beta-mediated growth inhibition compared to control cells. Ninety-eight percent of cell count growth inhibition observed in YAMC cells, while 34% inhibition was observed in Smad3-/- cells after TGF-beta treatment. ((3)H)-thymidine incorporation was inhibited by 61% in YAMC cells, while Smad3-/- cells showed 25% inhibition after TGF-beta treatment. Smad3-/- cells were deficient in luciferase reporter induction by TGF-beta. TGF-beta induced apoptosis 8-fold in YAMC cells, but had no effect on apoptosis in Smad3-/- cells. p21(Cip11) and PAI-1 are induced in YAMC cells by TGF-beta, but unchanged in Smad3-/- cells. TGF-beta decreases cyclin D1 levels in YAMC cells but does not affect levels in Smad3-/- cells. CONCLUSIONS Our findings suggest that the loss of Smad3 contributes to resistance of TGF-beta growth inhibition and apoptosis in colonic epithelium. This may represent a mechanism by which cells are able to escape antiproliferative controls and embark on a pathway toward neoplasia.

Tumor suppression by miR-26 overrides potential oncogenic activity in intestinal tumorigenesis.

Down-regulation of miR-26 family members has been implicated in the pathogenesis of multiple malignancies. In some settings, including glioma, however, miR-26-mediated repression of PTEN promotes tumorigenesis. To investigate the contexts in which the tumor suppressor versus oncogenic activity of miR-26 predominates in vivo, we generated miR-26a transgenic mice. Despite measureable repression of Pten, elevated miR-26a levels were not associated with malignancy in transgenic animals. We documented reduced miR-26 expression in human colorectal cancer and, accordingly, showed that miR-26a expression potently suppressed intestinal adenoma formation in Apc(min/+) mice, a model known to be sensitive to Pten dosage. These studies reveal a tumor suppressor role for miR-26 in intestinal cancer that overrides putative oncogenic activity, highlighting the therapeutic potential of miR-26 delivery to this tumor type.

Development and characterization of normal colonic epithelial cell lines derived from normal mucosa of patients with colon cancer

BACKGROUND Researchers have tried for at least 20 years to develop a normal human colonic cell line suitable for in vitro studies of human colonic diseases. We report a breakthrough development of two normal colon-derived cell lines. They are designated NCM356 and NCM425. MATERIALS AND METHODS The cells were collected from the histologically normal colonic margin of patients undergoing resection for colon adenocarcinomas and grown in culture. RESULTS Since NCM356 and NCM425 have now been subcultured 22 and 19 times, each has undergone more than 40 population doublings. Neither cell line has shown evidence of terminal differentiation. Immunohistochemical characterization studies demonstrated that they are epithelial cells. They variably expressed subsets of other markers, including tumor markers, but did not grow in soft agar. NCM356 did not form tumors, whereas NCM425 was tumorigenic in immunodeficient mice. CONCLUSION These two cell lines represent the first successful in vitro culture of human colonocytes derived from normal mucosa. NCM356 is closer to normal, but seems to represent an early stage of cell transformation, possibly correlated with immortalization. In contrast, in vitro culture of the NCM425 cell line appears to have selected for later progression to malignancy. These lines are important resources for studying colon cancer and the physiology of intestinal cells.

Survival impact of malignant pancreatic neuroendocrine and islet cell neoplasm phenotypes

The low incidence of malignant “functional” (F) or “nonfunctional” (NF) neuroendocrine islet cell tumors (ICTs) of the pancreas represents a challenge to precise post‐therapeutic survival prediction. This study examined the survival impact of malignant pancreatic ICT morphologic subtypes.

Update on Treatment Advances in Combined-Modality Therapy for Anal and Rectal Carcinomas

Concurrent radiation therapy and chemotherapy is the primary treatment for patients with squamous cell tumors of the anal canal, and is also employed in the neoadjuvant setting for patients with stage II and III adenocarcinoma of the rectum. There is constant clinical study involving modifications of chemoradiotherapy regimens in an effort to maximize tumor responses while reducing normal tissue toxicity. This review will discuss established regimens as well as newer and novel treatment approaches to treatment of anal and rectal cancer.

Emerging Role of Laparoscopic and Robotic Surgery for Rectal Cancers

The surgical management of rectal cancers is in a rapid phase of evolution that will increasingly deploy minimally invasive surgical (MIS) techniques. In this issue of Annals of Surgical Oncology are two articles about MIS approaches for rectal cancer, one comparing open versus laparoscopic proctectomy and the other comparing laparoscopic versus robotic approaches. These articles offer an opportunity to encourage the systematic validation of these technologies through clinical trials as they are increasingly adopted for colorectal surgery. Over the past decade, urologists have made great strides in implementing robotic surgery for pelvic procedures, although the surgical oncology and colorectal surgery communities have not yet embraced this technology at the same pace. For example, in 2007, approximately 50,000 radical prostatectomies were performed with the Da Vinci robot system in the United States, or approximately 60% of radical prostatectomies. In general, the reported results of robotic prostatectomy demonstrated less blood loss and shorter length of hospital stay; although the potency and continence rates were comparable, a trend was noted toward a faster return of functional outcomes. The gynecological community has also started to use the robotic system, which has shown similar results to those described by urologists for prostatectomy. That is, compared with open or laparoscopic techniques, robotic surgery for radical hysterectomy resulted in less blood loss, fewer postoperative complications, and shorter length of stay. Last year, Mattias Soop and Heidi Nelson, in an editorial published in Annals of Surgical Oncology, wrote, ‘‘we believe that the cumulative literature now supports an equipoise on short term advantages and long-term oncologic outcomes (for laparoscopic proctectomy for cancer), making the case for large prospective randomized trials.’’ Since the COST study group published its results in 2004 showing equivalence in oncologic outcomes between open and laparoscopic resection of colon cancer, the use of laparoscopic techniques for colon cancer has become popular and has now expanded to include rectal cancer patients. The data for rectal cancer is still being generated, but the randomized Conventional Versus Laparoscopic-Assisted Surgery in Colorectal Cancer (CLASICC trial), as well as several retrospective studies, demonstrate that the use of laparoscopic techniques has at least equivalent oncologic outcomes compared with an open laparotomy approach. For example, in this issue of Annals of Surgical Oncology is a multivariate analysis of 421 consecutive patients with stage II and stage III rectal cancer conducted by Law and colleagues who retrospectively compared outcomes of open versus laparoscopic resection. Laparoscopic resection was associated with significantly less blood loss and shorter hospital stay and was one of the independent significant factors associated with better survival (P = .03, hazard ratio .558, 95% confidence interval .339–.969). Ng and colleagues from Hong Kong reported last year in Annals of Surgical Oncology the preliminary results of a randomized trial comparing open versus laparoscopic abdominoperineal resection in 99 rectal cancer patients with a follow-up of 90 months. Their results showed that postoperative recovery was better after laparoscopic surgery, and 5-year survival was identical. These results are consistent with other studies showing that laparoscopic colon resection provides better perioperative outcomes compared with open laparotomy, including decreased postoperative pain, earlier return to normal physical function, quicker return to bowel function, and shorter hospital stays. Society of Surgical Oncology 2009

Presentation, Treatment, and Clinical Outcomes of Patients With Hepatocellular Carcinoma, With and Without Human Immunodeficiency Virus Infection

BACKGROUND & AIMS Liver-related complications such as hepatocellular carcinoma (HCC) are a major cause of morbidity and mortality in individuals infected with human immunodeficiency virus (HIV), particularly among those also infected with hepatitis B or hepatitis C viruses. There is a lack of consensus regarding the clinical presentation, treatment options, and outcomes in HIV-infected patients with HCC. We compared the clinical presentation, treatment, and survival of patients with HCC, with and without HIV infection. METHODS We conducted a retrospective cohort study of cirrhotic patients diagnosed with HCC at a large safety-net hospital between January 2005 and December 2010. Patients without known HIV serologic status were excluded. Demographic features, tumor characteristics, treatment regimens, and survival were compared between patients (n = 26) with and without HIV infection (n = 164). Survival curves were generated by using Kaplan-Meier plots and compared by using the log-rank test. RESULTS A higher percentage of HIV-infected patients presented with compensated liver disease (Child-Turcotte-Pugh stage A) than those without HIV infection (62% vs 32%, respectively; P = .01), as well as those with early-stage tumors (Barcelona Clinic Liver Cancer stage A, 39% vs 17%, respectively; P = .04 and Okuda stage I, 50% vs 21%, respectively; P < .01). HIV-infected patients were more likely to be cured of HCC than uninfected patients (27% vs 4%, respectively; P = .01), but median overall survival times were similar between groups (9.6 vs 5.2 months, respectively; P = .85). The 1-year rates of survival for HIV-infected and uninfected patients were 40% and 38%, respectively. CONCLUSIONS HIV-infected patients present with earlier-stage HCC and more preserved liver function than uninfected patients, resulting in more curative treatment options. Despite this difference, overall survival was similar between patients with HCC with and without HIV infection.