The Long Noncoding RNA Cardiac Mesoderm Enhancer-Associated Noncoding RNA (Carmn) Is a Critical Regulator of Gastrointestinal Smooth Muscle Contractile Function and Motility.

BACKGROUND & AIMS: Visceral smooth muscle cells (SMCs) are an integral component of the gastrointestinal (GI) tract that regulate GI motility. SMC contraction is regulated by posttranslational signaling and the state of differentiation. Impaired SMC contraction is associated with significant morbidity and mortality, but the mechanisms regulating SMC-specific contractile gene expression, including the role of long noncoding RNAs (lncRNAs), remain largely unexplored. Herein, we reveal a critical role of Carmn (cardiac mesoderm enhancer-associated noncoding RNA), an SMC-specific lncRNA, in regulating visceral SMC phenotype and contractility of the GI tract. METHODS: Genotype-Tissue Expression and publicly available single-cell RNA sequencing (scRNA-seq) data sets from embryonic, adult human, and mouse GI tissues were interrogated to identify SMC-specific lncRNAs. The functional role of Carmn was investigated using novel green fluorescent protein (GFP) knock-in (KI) reporter/knock-out (KO) mice. Bulk RNA-seq and single nucleus RNA sequencing (snRNA-seq) of colonic muscularis were used to investigate underlying mechanisms. RESULTS: Unbiased in silico analyses and GFP expression patterns in Carmn GFP KI mice revealed that Carmn is highly expressed in GI SMCs in humans and mice. Premature lethality was observed in global Carmn KO and inducible SMC-specific KO mice due to GI pseudo-obstruction and severe distension of the GI tract, with dysmotility in cecum and colon segments. Histology, GI transit, and muscle myography analysis revealed severe dilation, significantly delayed GI transit, and impaired GI contractility in Carmn KO vs control mice. Bulk RNA-seq of GI muscularis revealed that loss of Carmn promotes SMC phenotypic switching, as evidenced by up-regulation of extracellular matrix genes and down-regulation of SMC contractile genes, including Mylk, a key regulator of SMC contraction. snRNA-seq further revealed SMC Carmn KO not only compromised myogenic motility by reducing contractile gene expression but also impaired neurogenic motility by disrupting cell-cell connectivity in the colonic muscularis. These findings may have translational significance, because silencing CARMN in human colonic SMCs significantly attenuated contractile gene expression, including MYLK, and decreased SMC contractility. Luciferase reporter assays showed that CARMN enhances the transactivation activity of the master regulator of SMC contractile phenotype, myocardin, thereby maintaining the GI SMC myogenic program. CONCLUSIONS: Our data suggest that Carmn is indispensable for maintaining GI SMC contractile function in mice and that loss of function of CARMN may contribute to human visceral myopathy. To our knowledge this is the first study showing an essential role of lncRNA in the regulation of visceral SMC phenotype.

Clinicopathologic Features of Gastrointestinal Tract Langerhans Cell Histiocytosis.

Gastrointestinal (GI) tract involvement by Langerhans cell histiocytosis (LCH) is rare and its clinicopathologic characteristics have only been described in case reports and small series. We reviewed hematoxylin and eosin- and CD1a, S100, and Langerin immunohistochemical-stained slides from 47 patients with well-documented demographic and clinical findings. Our cases included 8 children and 39 adults, with a mean follow-up of 63 months. All pediatric patients had concurrent multisystem LCH, presented with GI symptoms, and showed non-polypoid lesions. Seven (88%) showed multifocal GI disease, including five with multiple GI organ involvement. All sampled lesions from children exhibited infiltrative growth. More than half had died of the disease or manifested persistent LCH at last follow-up. Twenty-five of 39 (64%) adults had LCH involving only the GI tract (single-system), with the remaining 14 (36%) exhibiting multi-system disease. Adult single-system GI LCH was typically encountered incidentally on screening/surveillance endoscopy (72%). Most exhibited isolated colorectal involvement (88%) as a solitary polyp (92%), with a well-demarcated/noninfiltrative growth pattern (70%), and excellent prognosis (100%). In comparison, adult patients with multi-system LCH more frequently presented with GI symptoms (92%, P<0.001), non-colorectal GI site involvement (50%, P=0.02), multifocal GI lesions (43%, P=0.005), non-polypoid lesions (71%, P<0.001), infiltrative histologic growth pattern (78%, P=0.04), and persistent disease (57%, P<0.001). Adult multi-system LCH patients appear to exhibit similar clinicopathologic features to those of pediatric patients. These results demonstrate that adults with single-system LCH involving the GI tract have an excellent prognosis, while multi-system LCH occurring at any age carries an unfavorable prognosis. High-risk features of GI LCH include pediatric age, GI symptomatology, non-colorectal GI involvement, multifocal GI disease, non-polypoid lesions, and infiltrative growth pattern.

Aberrant p53 expression is associated with neoplastic progression in Barrett oesophagus diagnosed as indefinite for dysplasia.

The aim of this study was to investigate the role of immunohistochemical (IHC) expression of p53 and other potential clinical parameters as prognostic markers for predicting neoplastic progression in Barrett oesophagus (BE) patients diagnosed as indefinite for dysplasia (IND). The study included patients with established BE of any extent who had a diagnosis of IND accompanied by concurrent p53 immunohistochemistry (IHC) stain at the index endoscopic procedure and at least one follow-up examination between 2000 and 2021. Correlation between disease progression from IND to higher-grade dysplasia [low-grade dysplasia (LGD), high-grade dysplasia (HGD) and oesophageal adenocarcinoma (EAC)] and clinicopathological parameters were analysed. A total of 149 patients (99 males; mean age 63.3 ± 10.0 years, range = 35-89) were included in the final analysis. Median follow-up was 37.1 months [interquartile range (IQR) = 20.5-59.1 months]. Progression rates from IND to LGD and HGD were 12.1% (18 of 149) and 2.7% (four of 149), respectively. On multivariate analysis, the number of IND diagnoses was significantly associated with progression to both LGD and HGD (P = 0.016 and P < 0.001, respectively). Cox regression analysis showed that aberrant p53 expression was significantly associated with progression to LGD [hazard ratio (HR) = 4.87, 95% confidence interval (CI) = 1.91-12.45, P = 0.001] and HGD (HR = 21.81, 95% CI = 1.88-253.70, P = 0.014). Kaplan-Meier survival analysis also demonstrated that aberrant p53 expression was significantly associated with progression to LGD (P < 0.001) and HGD (P = 0.001). Our results suggest that frequency of IND diagnoses and status of p53 expression can help to stratify risk of neoplastic progression in BE patients with IND.

Density of Biopsy Sampling Required to Ensure Accurate Histological Assessment of Inflammation in Active Ulcerative Colitis.

BACKGROUND: Histological response to treatment is an important outcome in patients with ulcerative colitis (UC). The accuracy of biopsy-based measurements of inflammation may be limited by error imposed by natural microscopic heterogeneity on the scale of individual biopsies. We determined the magnitude of this error, its histological correlates, and the density of biopsy sampling within mucosal regions of interest required to meet specified benchmarks for accuracy. METHODS: A total of 994 sequential 1-mm digital microscopic images (virtual biopsies) from consecutive colectomies from patients with clinically severe UC were scored by 2 pathologists. Agreement statistics for Geboes subscores and Nancy (NHI) and Robarts Histological Indices (RHI) between random samples from 1 to 10 biopsies and a reference mean score across a 2-cm region of mucosa were calculated using bootstrapping with 2500 iterations. RESULTS: The agreement statistics improved across all indices as the biopsy density increased, with the largest proportional gains occurring with addition of the second and third biopsies. One biopsy achieved moderate to good agreement with 95% confidence for NHI and RHI corresponding to scale-specific errors of 0.40 (0.25-0.66) and 3.02 (2.08-5.36), respectively; and 3 biopsies achieved good agreement with 95% confidence corresponding to scale-specific errors of 0.22 (0.14-0.39) and 1.87 (1.19-3.25), respectively. Of the individual histological features, erosions and ulcers had the greatest impact on the agreement statistics. CONCLUSIONS: In the setting of active colitis, up to 3 biopsy samples per region of interest may be required to overcome microscopic heterogeneity and ensure accurate histological grading.

Recognition of lyso-phospholipids by human natural killer T lymphocytes.

Natural killer T (NKT) cells are a subset of T lymphocytes with potent immunoregulatory properties. Recognition of self-antigens presented by CD1d molecules is an important route of NKT cell activation; however, the molecular identity of specific autoantigens that stimulate human NKT cells remains unclear. Here, we have analyzed human NKT cell recognition of CD1d cellular ligands. The most clearly antigenic species was lyso-phosphatidylcholine (LPC). Diacylated phosphatidylcholine and lyso-phosphoglycerols differing in the chemistry of the head group stimulated only weak responses from human NKT cells. However, lyso-sphingomyelin, which shares the phosphocholine head group of LPC, also activated NKT cells. Antigen-presenting cells pulsed with LPC were capable of stimulating increased cytokine responses by NKT cell clones and by freshly isolated peripheral blood lymphocytes. These results demonstrate that human NKT cells recognize cholinated lyso-phospholipids as antigens presented by CD1d. Since these lyso-phospholipids serve as lipid messengers in normal physiological processes and are present at elevated levels during inflammatory responses, these findings point to a novel link between NKT cells and cellular signaling pathways that are associated with human disease pathophysiology.

Human Intestinal Spirochetosis Incompatible With Dysplastic Adenomatous Epithelium.

Human intestinal spirochetosis (HIS) refers to the colonization of spirochetal bacteria in the human intestinal tract. HIS caused by Brachyspira spp. has been recognized for decades, but their pathological and clinical significance is largely unclear. The coincidence of dysplasia in adenoma or adenocarcinoma and HIS is very rare, and whether spirochetes can colonize on dysplastic epithelium remains controversial. Here, we report a case that showed abrupt abolition of mucosal surface fringe formation on a tubular adenoma (TA) and increased cytoplasmic MUC1 expression in the dysplastic epithelial cells compared with adjacent nondysplastic colonocytes. The findings support the hypothesis that the epithelial colonization of spirochetes is significantly reduced by dysplasia likely due to loss of microvilli, and an increase of epithelial MUC1 expression might contribute to reduced spirochetal colonization in colonic mucosa.

Heterotopic Mesenteric Ossification With Trilineage Hematopoiesis.

Heterotopic ossification (HO) histologically refers to extraskeletal bone formation in non-ossifying tissues, most commonly noted in the extremities, buttocks, abdominal wall, and hip joints. HO developing in the mesentery (heterotopic mesenteric ossification, HMO) is very rare, with fewer than 100 cases reported in the literature. It usually occurs in adult male patients with a history of repeated abdominal trauma. So far, only two cases of HMO have been reported with the development of hematopoietic bone marrow. Here, we report the third case of HMO with true trilineage hematopoiesis in a 66-year-old female with suspicious mesenteric-retained foreign material from prior surgical procedures, including hysterectomy for endometrial adenocarcinoma and multiple repairs for incisional hernia.

Nodular Histiocytic/Mesothelial Hyperplasia Mimicking Mesenteric Metastasis.

Nodular histiocytic/mesothelial hyperplasia (NHMH) is a rare histologic entity, characterized by localized benign reactive proliferation of histiocytes and mesothelial cells. The presence of this rare entity poses a challenge in differential diagnosis, both in radiological findings and pathological interpretations under certain circumstances, and consequently has been misdiagnosed as malignancy. Here, we report a case of mesenteric NHMH in a patient with colonic mucinous adenocarcinoma. Histology shows numerous large calretinin (+) mesothelial cells mixed with CD68 (+) histiocytes by immunohistochemistry. In contrast to almost all previously reported cases with typical features of histiocytic predominance, the current case of NHMH mainly consists of mesothelial cells with intermixed histiocytes. The findings expand the histologic spectrum of NHMH and contribute to awareness of this entity in the differential diagnosis.

Impact of pathological response after neoadjuvant chemotherapy on adjuvant therapy decisions and patient outcomes in gastrointestinal cancers.

BACKGROUND: Neoadjuvant chemotherapy (NAC) is frequently used in gastrointestinal cancers (GIC), and pathological, radiological, and tumor marker responses are assessed during and after NAC. AIM: To evaluate the relationship between pathologic, radiologic, tumor marker responses and recurrence-free survival (RFS), overall survival (OS), adjuvant chemotherapy (AC) decisions, and the impact of changing to a different AC regimen after poor response to NAC. METHODS AND RESULTS: Medical records of GIC patients treated with NAC at Mount Sinai between 1/2012 and 12/2018 were reviewed. One hundred fifty-six patients (58.3% male, mean age 63 years) were identified. Primary tumor sites were: 43 (27.7%) pancreas, 62 (39.7%) gastroesophageal, and 51 (32.7%) colorectal. After NAC, 31 (19.9%) patients had favorable pathologic response (FPR; defined as College of American Pathologists [CAP] score 0-1). Of 107 patients with radiological data, 59 (55.1%) had an objective response, and of 113 patients with tumor marker data, 61 (54.0%) had a ≥50% reduction post NAC. FPR, but not radiographic or serological responses, was associated with improved RFS (HR 0.28; 95% CI 0.11-0.72) and OS (HR 0.13; 95% CI 0.2-0.94). Changing to a different AC regimen from initial NAC, among all patients and specifically among those with unfavorable pathological response (UPR; defined as CAP score 2-3) after NAC, was not associated with improved RFS or OS. CONCLUSIONS: GIC patients with FPR after NAC experienced significant improvements in RFS and OS. Patients with UPR did not benefit from changing AC. Prospective studies to better understand the role of pathological response in AC decisions and outcomes in GIC patients are needed.

Natural killer T-cell autoreactivity leads to a specialized activation state.

Natural killer T (NKT) cells are innate-like T cells that recognize specific microbial antigens and also display autoreactivity to self-antigens. The nature of NKT-cell autoreactive activation remains poorly understood. We show here that the mitogen-activated protein kinase (MAPK) pathway is operative during human NKT-cell autoreactive activation, but calcium signaling is severely impaired. This results in a response that is biased toward granulocyte macrophage colony-stimulating factor (GM-CSF) secretion because this cytokine requires extracellular signal-regulated kinase (ERK) signaling but is not highly calcium dependent, whereas interferon-gamma (IFN-gamma), interleukin (IL)-4, and IL-2 production are minimal. Autoreactive activation was associated with reduced migration velocity but did not induce arrest; thus, NKT cells retained the ability to survey antigen presenting cells (APCs). IL-12 and IL-18 stimulated autoreactively activated NKT cells to secrete IFN-gamma, and this was mediated by Janus kinase-signal transducers and activators of transcription (JAK-STAT)-dependent signaling without induction of calcium flux. This pathway did not require concurrent contact with CD1d(+) APCs but was strictly dependent on preceding autoreactive stimulation that induced ERK activation. In contrast, NKT-cell responses to the glycolipid antigen alpha-galactosyl ceramide (alpha-GalCer) were dampened by prior autoreactive activation. These results show that NKT-cell autoreactivity induces restricted cytokine secretion and leads to altered basal activation that potentiates innate responsiveness to costimulatory cytokines while modulating sensitivity to foreign antigens.

Colonic Adenocarcinoma at Advanced Stage in Adolescence: Report of 2 Cases.

BACKGROUND: Carcinoma of colon is rare in children and adolescents. The staging criteria of the carcinoma is the same as those for adults. However, the pathogenetic background in pediatric cases is different from adults and usually involves mismatch repair gene mutations or familial polyposis syndromes. Case report. We describe two adolescents diagnosed with advanced stage colon carcinoma and discuss the histological appearance, testing for mismatch repair genes and contrast- it with carcinoma occurring in the setting of familial polyposis syndrome. CONCLUSION: Colonic carcinoma occurring in pediatric patients should prompt a work-up for mismatch repair gene mutation status. Despite higher stage of presentation, some of the pediatric patients may respond favorably to chemotherapy and surgical resection.

Increased immature T-cells detected by flow cytometry in post chemotherapeutic patients with acute myeloid leukemia, a case report and small series study.

Detection of minimal/measurable residual disease (MRD) in bone marrow specimens by flow cytometry is widely used in patients with T cell acute lymphoblastic leukemia (T-ALL). It plays a central role in guiding treatment and assessing prognosis. However, the occurrence of a normal physiologic reactive immature T-cell population in treated bone marrow is unknown. To investigate this, we examined 14 post chemotherapeutic bone marrow specimens with a T-ALL MRD flow cytometry panel. This included 9 acute myeloid leukemia (AML) and 5 T-ALL cases. Immature T-cells are defined as surface CD3 negative cells that coexpress cytoplasmic CD3 (cyCD3) and terminal deoxynucleotidyl transferase (TdT), or as cells that express CD34 with coexpression of multiple T-cell markers. Immature T-cells were present in 1 of 9 AML cases (11%), between day 20-31 post chemotherapy. Follow-up of this patient who had 4.00% cyCD3+ TdT+ immature T-cells, showed the population gradually decreased to 0.50% at day 31, 0.15% at day 46, and was undetectable (0.00%) at day 116. This population remained undetectable at the most current follow-up on day 147. This pilot study shows that a low level of cyCD3+ TdT+ immature T-cells may be present in post chemotherapeutic regenerating bone marrow and can be detectable by flow cytometry. Thus, extra caution should be taken when interpreting T-ALL MRD results, especially between days 20-31 post chemotherapy.

Increased SPARC expression is associated with neoadjuvant therapy in resectable pancreatic ductal adenocarcinoma.

Secreted Protein Acid and Rich in Cysteine (SPARC) is an extracellular glycoprotein secreted by fibroblasts and osteoblasts in normal tissues. SPARC overexpression occurs in multiple tumors including pancreatic ductal adenocarcinoma (PDAC) and may predict favorable response to nab-paclitaxel. The prognostic significance of SPARC expression in PDAC is unclear - some reports indicate SPARC overexpression associates with poor outcomes and others find no correlation. Considering neoadjuvant therapy enhances the stromal fibrosis of PDAC and taking into account that SPARC is a component of PDAC stromal fibrosis, we hypothesized that SPARC expression would be greater in neoadjuvant-treated versus treatment-naive PDAC. Quantitative immunohistochemistry was used to measure SPARC expression in resected PDAC in 74 cases of neoadjuvant treated PDAC and 95 cases of treatment-naïve PDAC. SPARC expression was increased 54% in neoadjuvant treated PDAC compared to treatment-naïve PDAC. These data indicate that increased SPARC expression correlates with neoadjuvant therapy in PDAC.

Modulation of CD1d-restricted NKT cell responses by CD4.

CD4+ and CD4- NKT cell populations have been shown to be functionally distinct, but the role of CD4 molecules in NKT cell activation is not clear. Here, we have used human CD1d-restricted NKT cell clones to investigate the contribution of CD4 to NKT cell functional responses. Coligation of CD4 with the TCR/CD3 complex resulted in enhanced cytokine secretion and increased calcium flux by CD4+ NKT cell clones, indicating that CD4 is functionally active in these cells. CD4 blockade specifically inhibited cytokine secretion and proliferation of CD4+ NKT cell clones in response to CD1d+ APCs but did not affect cytotoxicity, suggesting that CD4 preferentially modulates some NKT cell functional responses and not others. Anti-CD4 mAb treatment inhibited NKT cell responses to both MHC class II(+) and MHC class II(-) APCs, indicating that its effect was not due to blocking CD4 binding to MHC class II molecules on APCs. The inhibitory effect of the anti-CD4 mAb also did not require recognition of CD1d by the NKT cell, since calcium flux was reduced in response to anti-CD3 mAb stimulation. Western blot analysis revealed that anti-CD4 treatment resulted in increased phosphorylation of an inhibitory site of p56(lck) (tyrosine 505). Thus, CD4 blockade interferes with the course of CD3-mediated signaling events in NKT cells. These results indicate that CD4 can contribute to NKT cell activation independently of the presence of a CD4-ligand on APCs and suggest that it preferentially modulates cytokine and proliferative responses.

NKT cells direct monocytes into a DC differentiation pathway.

Monocytes can differentiate into macrophages or dendritic cells (DCs). The processes that promote their differentiation along one pathway rather than the other remain unknown. NKT cells are regulatory T cells that respond functionally to self and foreign antigens presented by CD1d molecules. Hence, in addition to contributing to antimicrobial responses, they may carry out autoreactively activated functions when there is no infectious challenge. However, the immunological consequences of NKT cell autoreactivity remain poorly understood. We show here that human NKT cells direct monocytes to differentiate into immature DCs. The ability to induce monocyte differentiation was CD1d-dependent and appeared specific to NKT cells. Addition of exogenous antigens or costimulation from IL-2 was not required but could enhance the effect. DC differentiation was a result of NKT cell secretion of GM-CSF and IL-13, cytokines that were produced by the NKT cells upon autoreactive activation by monocytes. NKT cells within PBMC samples produced GM-CSF and IL-13 upon exposure to autologous monocytes directly ex vivo, providing evidence that such NKT cell-autoreactive responses can occur in vivo. These results show that when NKT cells are activated by autologous monocytes, they are capable of providing factors that specifically direct monocyte differentiation into immature DCs. Thus, autoreactively activated NKT cells may contribute to the maintenance of the immature DC population, and microbial infection or inflammatory conditions that activate NKT cells further could stimulate them to promote an increased rate of DC differentiation.

Fatal pulmonary embolism and pulmonary hemorrhage in lupus anticoagulant hypoprothrombinemia syndrome: a case report and review of literature.

: Lupus anticoagulant hypoprothrombinemia syndrome (LAHS) is a rare disorder characterized by development of lupus anticoagulant and antiprothrombin antibodies. The most common clinical manifestation is bleeding. Clinical management can be challenging due to the subtle balance between the bleeding and thrombotic tendencies. We report a novel case of LAHS in which the patient experienced the sequence of hemorrhage-thrombosis-hemorrhage before eventually dying of fatal pulmonary embolism and pulmonary hemorrhage. Specifically, she presented with multiple gastrointestinal bleeding episodes, followed by multifocal subdural hematomas, pulmonary embolism after normalization of prothrombin activity levels with immunosuppression, and finally with fatal pulmonary hemorrhage after enoxaparin treatment for pulmonary embolism. This case illustrates the importance of recognizing early minor bleeding episodes, and detecting specific antiprothrombin antibodies, in the diagnosis of LAHS. Furthermore, it highlights the complex challenge of normalizing prothrombin activity levels while at the same time preventing medical complications.

Intracellular protein phosphorylation in adherent U937 monocytes mediated by various culture conditions and fibronectin-derived surface ligands.

Macrophages play a central role in the normal healing process after tissue injury and the host response to foreign objects such as biomaterials. The process leading to macrophage adhesion and activation on protein-adsorbed substrates is complex and unresolved. While the use of primary cells offers clinical relevancy, macrophage cell lines offer unique advantages such as availability and relatively homogeneous phenotype as models to probe the molecular mechanism of cell-surface interaction. Our goal was to better characterize the effect of the culture condition and surface-associated ligands on the extent of U937 adhesion. Tyrosine phosphorylation of intracellular proteins was surveyed as a basis to seek a greater understanding of the molecular mechanism involved in mediating U937 adhesion on various ligand-adsorbed surfaces. U937 viability and adhesion on tissue culture polystyrene (TCPS) increased with (i) increasing serum level, (ii) decreasing tyrosine phosphorylation inhibitor AG18 concentration, or (iii) increasing culture time. The adsorption of various adhesion proteins such as fibronectin and peptide ligands (i.e., RGD, PHSRN) on TCPS did not significantly increase the adherent density of U937 when compared with albumin and PBS ligand controls. However, ligand identity and the presence of phorbol myristate acetate dramatically affected the extent (i.e., increase or decrease) and the identity (i.e., molecular weight) of phosphotyrosine proteins in adherent U937 in a time-dependent manner. The extent and identity of phosphotyrosine proteins did not exhibit a clear AG18 dose dependency, rather the level of tyrosine phosphorylation for a distinct group of proteins was either increased or decreased for a given AG18 concentration.

Less cytotoxicity to combination therapy of 5-fluorouracil and cisplatin than 5-fluorouracil alone in human colon cancer cell lines.

AIM: Our previous studies showed increased sensitivity to 5-FU in colon cancer cell lines with microsatellite instability, and considered that mutations of TGFbeta-R II, IGF IIR, RIZ gene might enhance the potentials of cell growth and proliferation, which increased the sensitivity to 5-FU. Here we compared the distribution of cell cycle and P53 status between two human colon cancer cell lines with different sensitivity to 5-FU. Because mechanistic differences exist between 5-FU and CDDP, we also analyzed the efficacy of CDDP and combination therapy on two human colon cancer cell lines. METHODS: We compared the sensitivity to CDDP of these two cell lines by MTT assay. Distribution of cell cycle under treatment of 5-FU, CDDP alone or both was analyzed by Flow Cytometry, and expression of P53 was detected by immunocytochemical staining. RESULTS: SW480 cells were more sensitive to CDDP than LoVo cells at the concentrations above 16 micromol/l (Ratio of absorption is 0.64 and 0.79 at 16 micromol/l, respectively; P<0.01). Efficacy of combination therapy was conversely lower than that of single-therapy of 5-FU (Ratio of absorption in LoVo+5-FU, SW480+5-FU, LoVo+5-FU+CDDP and SW480+5-FU+CDDP is 0.53, 0.54, 0.72, 0.78, respectively; P<0.01). LoVo cells were negative whereas SW480 cells positive in P53 expression. 5-FU induced G1-phase arrest in both cell lines, but LoVo cells peaked 24 hours earlier than SW480 cells, and 48 hours earlier for an apparent hypodiploid DNA. However, CDDP showed the contrary, inducing S-phase arrest, and SW480 cells peaking 36 hours earlier. Both cell lines showed hypodipliod nuclei 48 hours after CDDP treatment. Percentage of cells in G1-phase and S-phase dominated alternatively under combination therapy in both cell lines. CONCLUSION: These results suggest that colon cancer cells with microsatellite instability are more sensitive to 5-FU, whereas more resistant to CDDP. Combination therapy of 5-FU and CDDP shows fewer efficacies than 5-FU single-therapy, although it can render a cell cycle arrest. P53 may be involved in the shift of G1-phase to S-phase, but inessentially.

Increased sensitivity of colorectal cancer cell lines with microsatellite instability to 5-fluorouracil in vitro.

OBJECTIVE: To study the relationship between sensitivity to 5-FU and the status of a panel of microsatellite loci in three human colon cancer cell lines. METHODS: Cell viability in several concentrations of 5-FU was assessed by the MTT test. Expression of hMSH2 and hMLH1 in LoVo, SW480 and SW1116 cells were analyzed by immunocytochemical staining.Ten mononucleotide and dinucleotide microsatellite loci were analyzed by the PCR-SSLP-silver staining method. RESULTS: By MTT assay, it showed that LoVo cells were more sensitive than SW480 and SW1116 cells (0.8 micromol/L,2.2 micromol/L and 1.9 micromol/L, respectively, P < 0.05). By immunocytochemical staining, hMSH2 was expressed in SW480 and SW1116 cells but not in LoVo cells, while hMLH1 was positive in all three cell lines. The PCR-SSLP-silver staining of 10 microsatellite loci revealed that LoVo cells had a different pattern of electrophoretic bands compared with SW480 and SW1116 cells, manifesting both additions and band-shifts. CONCLUSION: Together with hMSH2 and hMLH1, the status of a panel of microsatellite loci may be used as convenient predictors for drug-optimization or prognosis-assessment in colorectal cancer patients before chemotherapy.