The C1q and gC1qR axis as a novel checkpoint inhibitor in cancer.

Understanding at the molecular level of the cell biology of tumors has led to significant treatment advances in the past. Despite such advances however, development of therapy resistance and tumor recurrence are still unresolved major challenges. This therefore underscores the need to identify novel tumor targets and develop corresponding therapies to supplement existing biologic and cytotoxic approaches so that a deeper and more sustained treatment responses could be achieved. The complement system is emerging as a potential novel target for cancer therapy. Data accumulated to date show that complement proteins, and in particular C1q and its receptors cC1qR/CR and gC1qR/p33/HABP1, are overexpressed in most cancer cells and together are involved not only in shaping the inflammatory tumor microenvironment, but also in the regulation of angiogenesis, metastasis, and cell proliferation. In addition to the soluble form of C1q that is found in plasma, the C1q molecule is also found anchored on the cell membrane of monocytes, macrophages, dendritic cells, and cancer cells, via a 22aa long leader peptide found only in the A-chain. This orientation leaves its 6 globular heads exposed outwardly and thus available for high affinity binding to a wide range of molecular ligands that enhance tumor cell survival, migration, and proliferation. Similarly, the gC1qR molecule is not only overexpressed in most cancer types but is also released into the microenvironment where it has been shown to be associated with cancer cell proliferation and metastasis by activation of the complement and kinin systems. Co-culture of either T cells or cancer cells with purified C1q or anti-gC1qR has been shown to induce an anti-proliferative response. It is therefore postulated that in the tumor microenvironment, the interaction between C1q expressing cancer cells and gC1qR bearing cytotoxic T cells results in T cell suppression in a manner akin to the PD-L1 and PD-1 interaction.

Unraveling the complexities of early-onset colorectal cancer: a perspective on dietary and microbial influences.

While advances in screening have resulted in declining rates of colorectal cancer (CRC) among adults ≥50 years of age since the mid-2000s, the incidence of early-onset CRC (EOCRC) has steadily increased over the last decade. This increase is not fully accounted for by hereditary factors, and the hypothesis that a sedentary lifestyle and obesity are the primary culprits is not fully supported by recent reports indicating that many affected individuals lead active lifestyles, maintain normal weight, and are otherwise healthy. Attention has shifted toward dietary patterns, notably the consumption of processed and ultra-processed foods found in Western diets, which are suspected of disrupting the gut microbiome balance that potentially leads to EOCRC. The impact of antibiotic use on the gut microbiome is also posited as a contributing factor, given its rising prevalence in medical and agricultural practices. We propose that a paradigm shift is necessary for EOCRC research, moving beyond metabolic factors to a broader exploration of dietary and microbial influences. Future research must prioritize understanding the relationship between dietary habits, particularly processed food intake, antibiotic exposure, and gut microbiome dynamics, to unravel the complex etiology of EOCRC. This will be crucial in developing comprehensive preventive strategies to address the increasing incidence of this malignancy in younger populations.

A systematic review of genetic ancestry as a risk factor for incidence of non-small cell lung cancer in the US.

Background: Non-Small Cell Lung Cancer (NSCLC), the leading cause of cancer-related death in the United States, is the most diagnosed form of lung cancer. While lung cancer incidence has steadily declined over the last decade, disparities in incidence and mortality rates persist among African American (AA), Caucasian American (CA), and Hispanic American (HA) populations. Researchers continue to explore how genetic ancestry may influence differential outcomes in lung cancer risk and development. The purpose of this evaluation is to highlight experimental research that investigates the differential impact of genetic mutations and ancestry on NSCLC incidence. Methods: This systematic review was conducted using PubMed and Google Scholar search engines. The following key search terms were used to select articles published between 2011 and 2022: "African/European/Latin American Ancestry NSCLC"; "Racial Disparities NSCLC"; "Genetic Mutations NSCLC"; "NSCLC Biomarkers"; "African Americans/Hispanic Americans/Caucasian Americans NSCLC incidence." Systematic reviews, meta-analyses, and studies outside of the US were excluded. A total of 195 articles were initially identified and after excluding 156 which did not meet eligibility criteria, 38 were included in this investigation. Results: Studies included in this analysis focused on racial/ethnic disparities in the following common genetic mutations observed in NSCLC: KRAS, EGFR, TP53, PIK3CA, ALK Translocations, ROS-1 Rearrangements, STK11, MET, and BRAF. Results across studies varied with respect to absolute differential expression. No significant differences in frequencies of specific genetic mutational profiles were noted between racial/ethnic groups. However, for HAs, lower mutational frequencies in KRAS and STK11 genes were observed. In genetic ancestry level analyses, multiple studies suggest that African ancestry is associated with a higher frequency of EGFR mutations. Conversely, Latin ancestry is associated with TP53 mutations. At the genomic level, several novel predisposing variants associated with African ancestry and increased risk of NSCLC were discovered. Family history among all racial/ethnic groups was also considered a risk factor for NSCLC. Conclusion: Results from racially and ethnically diverse studies can elucidate driving factors that may increase susceptibility and subsequent lung cancer risk across different racial/ethnic groups. Identification of biomarkers that can be used as diagnostic, prognostic, and therapeutic tools may help improve lung cancer survival among high-risk populations.

IL-1ß enhances cell viability and decreases 5-FU sensitivity in novel colon cancer cell lines derived from African American patients.

Background: In the U.S., African Americans (AAs) present with the highest incidence and mortality rates for Colorectal Cancer (CRC). When compared to Caucasian American (CA) patients, AAs also have reduced response to the first line standard of care chemotherapeutic agent 5-Fluorouracil (5-FU). Previously, we observed differential gene expression between the two populations, suggesting that colon tumors from AA patients display a decreased antitumor immune response and an increased expression of genes encoding proteins involved in inflammatory processes, such as Interleukin-1ß (IL-1ß). Here, we investigate the role of IL-1ß in modifying chemotherapeutic response and altering expression of proteins in novel AA and well-established CA colon cancer cell lines. Methods: RNA sequencing analysis was performed to detect expression of genes involved in inflammation in AA and CA colon cancer cells. The effects of IL-1ß on 5-FU response was evaluated by assessing cell viability (MTS assay) and apoptosis (flow cytometry analysis) following treatment with 5-FU alone or in combination with the cytokine. Further, we used an IL-1 receptor antagonist (IL-1Ra) to inhibit IL-1ß-induced effects on 5-FU sensitivity and NF-kB pathway activation. Results: AA colon cancer cell lines present significant increase in expression of genes IL1R2 (373-fold change (FC), IRAK1 (3.24 FC), IKBKB, (5.33 FC) NF-KB IA (5.95 FC), MYD88, (3.72 FC), IRAK3 (161 FC), TRAF5 (4.1 FC). A significant decrease in the response to 5-FU treatment, as well as a significant increase in phosphorylation of IκBα and secretion of IL-8, was seen following IL-1ß treatment, in both AA and CA cell lines. Finally, treatment with IL-1Ra was able to reverse the effects induced by IL-1ß, by increasing the cells sensitivity to 5-FU. IL-1Ra also inhibited phosphorylation of IκBα and IL-8 secretion. Conclusions: Our results suggest a differential expression of inflammatory genes and proteins that might regulate the different response to IL-1ß between AA and CA colon cancer cell lines. Our data also demonstrates that IL-1ß is involved in modulating 5-FU response in both AA and CA colon cancer cell lines. Further investigation of these mechanisms might help elucidate the differences seen in incidence, mortality and response to therapy in AA colon cancer patients.

Immune-Related Gene Expression and Cytokine Secretion Is Reduced Among African American Colon Cancer Patients.

Background: Colorectal cancer is the third most deadly cancer among African Americans (AA). When compared to Caucasian Americans (CA), AA present with more advanced disease and lower survival rates. Here, we investigated if differences in tumor immunology could be contributive to disparities observed between these populations. Methods: We examined gene expression of tumor and non-tumor adjacent tissues from AA and CA by whole transcriptome sequencing, and generated scores for immune cell populations by NanoString. In addition, we utilized "The Cancer Genome Atlas" (TCGA) database from AA and CA as a validation cohort. Finally, we measured the secretion of cytokines characteristic of effector T helper cell (Th) subsets by ELISA using plasma from each AA and CA participant. Results: Colon tumors from AA patients showed significant fold-change increase in gene expression when compared to CA for FOXP3 (6.22 vs. 3.22), IL1B (103 vs. 11.4) and IL8 (220 vs. 28.9) (p < 0.05). In contrast, among CA we observed statistically higher gene expression of markers associated with antitumor activity such as GZMB (Granzyme B), IFNG and the immunotherapy targets PDL1 (CD274) and CTLA4 (p < 0.05). TCGA data validated our observed higher gene expression of GZMB and PDL1 in CA patients when compared to AA. Notably, our observations on immune cell populations show that AA tumors have significantly higher number of exhausted CD8+ cells (p < 0.01), mast cells (p < 0.02) and increased T regulatory cells when compared to CA. AA colon cancer patients differed from CA in cytokine production patterns in plasma (i.e., reduced IL-12). Conclusions: Our study demonstrates significant differences of the immunological profiles of colon tumors from AA compared to CA that suggest a deficiency of appropriate immune defense mechanisms in terms of gene expression, recruitment of immune cells and systemic secretion of cytokines. As such, these immune differences could be mitigated through population-specific therapeutic approaches.

Phospho-valproic acid (MDC-1112) reduces pancreatic cancer growth in patient-derived tumor xenografts and KPC mice: enhanced efficacy when combined with gemcitabine.

New chemotherapeutic agents are needed for pancreatic cancer (PC). We have previously shown that phospho-valproic acid (MDC-1112) is effective in cell-line xenografts of PC. Here, we explored whether MDC-1112 is effective in additional clinically relevant animal models of PC and whether MDC-1112 enhances the anticancer effect of clinically used chemotherapeutic agents. MDC-1112 alone strongly reduced patient-derived pancreatic tumor xenograft growth, and extended survival of LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre (KPC) mice. In both models, MDC-1112 inhibited STAT3 activation and its downstream signals, including Bcl-xL and cyclin D1. In human PC cell lines, P-V enhanced the growth inhibitory effect of gemcitabine (GEM), Abraxane and 5-FU, but not that of irinotecan. Normal human pancreatic epithelial cells were more resistant to the cytotoxic effects of MDC-1112/GEM combination. Furthermore, MDC-1112 enhanced GEM's effect on colony formation, apoptosis, cell migration, and cell invasion. In vivo, MDC-1112 and GEM, given alone, reduced patient-derived pancreatic tumor xenograft growth by 58% and 87%, respectively; whereas MDC-1112/GEM combination reduced tumor growth by 94%, inducing tumor stasis. In conclusion, MDC-1112 should be further explored as a potential agent to be used in combination with GEM for treating PC.

Loss of the Krüppel-like factor 4 tumor suppressor is associated with epithelial-mesenchymal transition in colorectal cancer.

AIM: Colorectal cancer (CRC) is the third leading cancer-related cause of death due to its propensity to metastasize. Epithelial-mesenchymal transition (EMT) is a multistep process important for invasion and metastasis of CRC. Krüppel-like factor 4 (KLF4) is a zinc finger transcription factor highly expressed in differentiated cells of the intestinal epithelium. KLF4 has been shown to play a tumor suppressor role during CRC tumorigenesis - its loss accelerates development and progression of cancer. The present study examined the relationship between KLF4 and markers of EMT in CRC. METHODS: Immunofluorescence staining for KLF4 and EMT markers was performed on archived patient samples after colorectal cancer resection and on colonic tissues of mice with colitis-associated cancer. RESULTS: We found that KLF4 expression is lost in tumor sections obtained from CRC patients and in those of mouse colon following azoxymethane and dextran sodium sulfate (AOM/DSS) treatment when compared to their respective normal appearing mucosa. Importantly, in CRC patient tumor sections, we observed a negative correlation between KLF4 levels and mesenchymal markers including TWIST, ß-catenin, claudin-1, N-cadherin, and vimentin. Similarly, in tumor tissues from AOM/DSS-treated mice, KLF4 levels were negatively correlated with mesenchymal markers including SNAI2, ß-catenin, and vimentin and positively correlated with the epithelial marker E-cadherin. CONCLUSION: These findings suggest that the loss of KLF4 expression is a potentially significant indicator of EMT in CRC.

Establishment of three novel cell lines derived from African American patients with colorectal carcinoma: A unique tool for assessing racial health disparity.

The incidence and mortality rates of colorectal carcinoma (CRC) are higher among African Americans (AAs) compared with Caucasian Americans (CAs). To assess the molecular properties associated with racial health disparity, three cell lines derived from colorectal tumors of three AA subjects were established. Cellular and molecular characterization of the cell lines designated CHTN06, SB501 and SB521 was performed using standard technologies, including immunofluorescence, electron microscopy, karyotyping, reverse transcription-polymerase chain reaction, ELISA and immunoblot analysis. The histology and morphology of CHTN06 xenografts were examined by hematoxylin and eosin staining. A total of three AA CRC cell lines derived from primary tumors were established and characterized. These cell lines were successfully cultured without immortalization and were found to be tumorigenic as mouse xenografts. In the present study, immunoblotting and immunofluorescence confirmed the expression of proteins known to be dysregulated in CRC, such as p53, DNA mismatch repair proteins and villin-1. Oncogenic miRNAs (i.e., miR-17, miR-21, miR-182, miR-210 and miR-222) were overexpressed in the AA CRC lines compared with the CA CRC lines (HT-29, HCT116 and SW480). Additionally, the AA CRC cell lines exhibited a differential inflammatory profile compared with HT-29 (CA CRC cell line); specifically noted was IL-8 secretion in response to inflammatory stimuli. In conclusion, three novel cell lines derived from AA CRC tissues were generated. These cell lines were characterized as epithelial in nature and exhibited differential expression of several miRNAs and inflammatory responses compared with commercially available cell lines of CA origin. The CRC cell lines CHTN06, SB501 and SB521 represent novel tools that may be used to provide diverse in vitro and in vivo models for studying CRC and racial health disparity.

A novel tricarbonylmethane agent (CMC2.24) reduces human pancreatic tumor growth in mice by targeting Ras.

Pancreatic Cancer (PC) is a deadly disease in need of new therapeutic options. We recently developed a novel tricarbonylmethane agent (CMC2.24) as a therapeutic agent for PC, and evaluated its efficacy in preclinical models of PC. CMC2.24 inhibited the growth of various human PC cell lines in a concentration and time-dependent manner. Normal human pancreatic epithelial cells were resistant to CMC2.24, indicating selectivity. CMC2.24 reduced the growth of subcutaneous and orthotopic PC xenografts in mice by up to 65% (P < 0.02), and the growth of a human patient-derived tumor xenograft by 47.5% (P < 0.03 vs vehicle control). Mechanistically, CMC2.24 inhibited the Ras-RAF-MEK-ERK pathway. Based on Ras Pull-Down Assays, CMC2.24 inhibited Ras-GTP, the active form of Ras, in MIA PaCa-2 cells and in pancreatic acinar explants isolated from Kras mutant mice, by 90.3% and 89.1%, respectively (P < 0.01, for both). The inhibition of active Ras led to an inhibition of c-RAF, MEK, and ERK phosphorylation by 93%, 91%, and 87%, respectively (P < 0.02, for all) in PC xenografts. Furthermore, c-RAF overexpression partially rescued MIA PaCa-2 cells from the cell growth inhibition by CMC2.24. In addition, downstream of ERK, CMC2.24 inhibited STAT3 phosphorylation levels at the serine 727 residue, enhanced the levels of superoxide anion in mitochondria, and induced intrinsic apoptosis as shown by the release of cytochrome c from the mitochondria to the cytosol and the further cleavage of caspase 9 in PC cells. In conclusion, CMC2.24, a potential Ras inhibitor, is an efficacious agent for PC treatment in preclinical models, deserving further evaluation.

Correction: Aberrant DNA Methylation: Implications in Racial Health Disparity.

[This corrects the article DOI: 10.1371/journal.pone.0153125.].

Aberrant DNA Methylation: Implications in Racial Health Disparity.

BACKGROUND: Incidence and mortality rates of colorectal carcinoma (CRC) are higher in African Americans (AAs) than in Caucasian Americans (CAs). Deficient micronutrient intake due to dietary restrictions in racial/ethnic populations can alter genetic and molecular profiles leading to dysregulated methylation patterns and the inheritance of somatic to germline mutations. MATERIALS AND METHODS: Total DNA and RNA samples of paired tumor and adjacent normal colon tissues were prepared from AA and CA CRC specimens. Reduced Representation Bisulfite Sequencing (RRBS) and RNA sequencing were employed to evaluate total genome methylation of 5'-regulatory regions and dysregulation of gene expression, respectively. Robust analysis was conducted using a trimming-and-retrieving scheme for RRBS library mapping in conjunction with the BStool toolkit. RESULTS: DNA from the tumor of AA CRC patients, compared to adjacent normal tissues, contained 1,588 hypermethylated and 100 hypomethylated differentially methylated regions (DMRs). Whereas, 109 hypermethylated and 4 hypomethylated DMRs were observed in DNA from the tumor of CA CRC patients; representing a 14.6-fold and 25-fold change, respectively. Specifically; CHL1, 4 anti-inflammatory genes (i.e., NELL1, GDF1, ARHGEF4, and ITGA4), and 7 miRNAs (of which miR-9-3p and miR-124-3p have been implicated in CRC) were hypermethylated in DNA samples from AA patients with CRC. From the same sample set, RNAseq analysis revealed 108 downregulated genes (including 14 ribosomal proteins) and 34 upregulated genes (including POLR2B and CYP1B1 [targets of miR-124-3p]) in AA patients with CRC versus CA patients. CONCLUSION: DNA methylation profile and/or products of its downstream targets could serve as biomarker(s) addressing racial health disparity.

Differential expression of miRNAs in colon cancer between African and Caucasian Americans: implications for cancer racial health disparities.

Colorectal cancer (CRC) incidence and mortality are higher in African Americans (AAs) than in Caucasian Americans (CAs) and microRNAs (miRNAs) have been found to be dysregulated in colonic and other neoplasias. The aim of this exploratory study was to identify candidate miRNAs that could contribute to potential biological differences between AA and CA colon cancers. Total RNA was isolated from tumor and paired adjacent normal colon tissue from 30 AA and 31 CA colon cancer patients archived at Stony Brook University (SBU) and Washington University (WU)­St. Louis Medical Center. miRNA profiles were determined by probing human genome-wide miRNA arrays with RNA isolated from each sample. Using repeated measures analysis of variance (RANOVA), miRNAs were selected that exhibited significant (p<0.05) interactions between race and tumor or significant (fold change >1.5, p<0.05) main effects of race and/or tumor. Quantitative polymerase chain reaction (q-PCR) was used to confirm miRNAs identified by microarray analysis. Candidate miRNA targets were analyzed using immunohistochemistry. RANOVA results indicated that miR-182, miR152, miR-204, miR-222 and miR-202 exhibited significant race and tumor main effects. Of these miRNAs, q-PCR analysis confirmed that miR-182 was upregulated in AA vs. CA tumors and exhibited significant race:tumor interaction. Immunohistochemical analysis revealed that the levels of FOXO1 and FOXO3A, two potential miR-182 targets, are reduced in AA tumors. miRNAs may play a role in the differences between AA and CA colon cancer. Specifically, differences in miRNA expression levels of miR-182 may contribute to decreased survival in AA colon cancer patients.

Preliminary anti-cancer photodynamic therapeutic in vitro studies with mixed-metal binuclear ruthenium(II)-vanadium(IV) complexes.

We report the synthesis and characterisation of mixed-metal binuclear ruthenium(II)-vanadium(IV) complexes, which were used as potential photodynamic therapeutic agents for melanoma cell growth inhibition. The novel complexes, [Ru(pbt)2(phen2DTT)](PF6)2·1.5H2O 1 (where phen2DTT = 1,4-bis(1,10-phenanthrolin-5-ylsulfanyl)butane-2,3-diol and pbt = 2-(2'-pyridyl)benzothiazole) and [Ru(pbt)2(tpphz)](PF6)2·3H2O 2 (where tpphz = tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]phenazine) were synthesised and characterised. Compound 1 was reacted with [VO(sal-L-tryp)(H2O)] (where sal-L-tryp = N-salicylidene-L-tryptophanate) to produce [Ru(pbt)2(phen2DTT)VO(sal-L-tryp)](PF6)2·5H2O 4; while [VO(sal-L-tryp)(H2O)] was reacted with compound 2 to produce [Ru(pbt)2(tpphz)VO(sal-L-tryp)](PF6)2·6H2O 3. All complexes were characterised by elemental analysis, HRMS, ESI MS, UV-visible absorption, ESR spectroscopy, and cyclic voltammetry, where appropriate. In vitro cell toxicity studies (with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay) via dark and light reaction conditions were carried out with sodium diaqua-4,4',4'',4''' tetrasulfophthalocyaninecobaltate(II) (Na4[Co(tspc)(H2O)2]), [VO(sal-L-tryp)(phen)]·H2O, and the chloride salts of complexes 3 and 4. Such studies involved A431, human epidermoid carcinoma cells; human amelanotic malignant melanoma cells; and HFF, non-cancerous human skin fibroblast cells. Both chloride salts of complexes 3 and 4 were found to be more toxic to melanoma cells than to non-cancerous fibroblast cells, and preferentially led to apoptosis of the melanoma cells over non-cancerous skin cells. The anti-cancer property of the chloride salts of complexes 3 and 4 was further enhanced when treated cells were exposed to light, while no such effect was observed on non-cancerous skin fibroblast cells. ESR and (51)V NMR spectroscopic studies were also used to assess the stability of the chloride salts of complexes 3 and 4 in aqueous media at pH 7.19. This research illustrates the potential for using mixed-metal binuclear ruthenium(II)-vanadium(IV) complexes to fight skin cancer.

A novel NSAID derivative, phospho-ibuprofen, prevents AOM-induced colon cancer in rats.

The cancer chemopreventive properties and gastrointestinal toxicity of ibuprofen are well documented. Modification of existing NSAIDs has improved on the chemopreventive efficacy of this agent and reduced its toxicity. In this study, ibuprofen and a modified derivative (phospho-modified ibuprofen or p-ibuprofen) were used in a chemically induced model of colon cancer. Fisher 344 rats were injected with azoxymethane then treated with either ibuprofen (500 ppm) or p-ibuprofen (900 ppm) for 20 weeks to observe aberrant crypt foci (ACF) or 40 weeks to evaluate tumor incidence and multiplicity. ß-catenin and p65 were measured in colonic tissues by immunofluorescence staining. Equal molar doses of ibuprofen (75 and 670 mg/kg) and p-ibuprofen (135 and 1,215 mg/kg) were administered to rats for 7 days to assess acute toxicity. The in vitro effect of p-ibuprofen on COX-2 and PGE(2) synthesis, ß-catenin expression and NF-κB activity were examined in RAW 264.7 macrophage and HCT 116 colon cancer cells. At week 20, p-ibuprofen and ibuprofen significantly reduced the multiplicity of ACF compared with control (p<0.05); 31.2 and 37.9%, respectively. At week 40, p-ibuprofen and ibuprofen reduced the multiplicity of colon tumors compared with control (p<0.01) by 47.2 and 56.6%, respectively. Equal molar concentrations of ibuprofen (670 mg/kg) and p-ibuprofen (1,215 mg/kg) resulted in stomach ulceration in 85.7% (6 out of 7) and 14.3% (1 out of 7) of rats, respectively, with p<0.01. Immunofluoresence staining and western blot analysis demonstrated that both ibuprofen and p-ibuprofen suppressed ß-catenin nuclear translocation in colon cancer cells. In addition, p-ibuprofen but not ibuprofen inhibited NF-κB activation in colon cancer cells. Collectively, these results suggest that p-ibuprofen is a potential effective novel drug for long-term use in colon cancer prevention.

The Effect of Race/Ethnicity on the Age of Colon Cancer Diagnosis.

BACKGROUND: Colorectal cancer is the third most commonly diagnosed cancer in the United States. Notably, racial/ethnic disparities exist in both incidence and mortality. PURPOSE: The aim of this case study was to investigate the impact of race/ethnicity on age at diagnosis of colorectal cancer in a defined population in Suffolk County, NY. METHODS: Data were retrospectively collected on race/ethnicity, health insurance status, age at diagnosis, stage at diagnosis, gender, smoking status, alcohol intake, tumor location, and body mass index for colorectal cancer patients with medical records in the Stony Brook University Medical Center database (2005-2011). Population-based data on Hispanic and non-Hispanic Whites were obtained from the Surveillance, Epidemiology, and End Results registry of New York State for an overlapping time period. Permutation-based ANCOVA and logistic regression with stepwise variable selection were conducted to identify covariates and first-order interactions associated with younger age at diagnosis and cancer stage as a dependent categorical variable. RESULTS: Of 328 colorectal cancer patients, Hispanics were diagnosed at a median younger age of 57y vs. 67y than non-Hispanic Whites (FDR = 0.001). Twenty-six percent of Hispanics were diagnosed with colorectal cancer prior to the recommended age (50y) for colorectal cancer surveillance compared to 11% of non-Hispanic Whites (FDR =0.007). Analysis of New York State registry data corroborated our findings that Hispanic colorectal cancer patients were diagnosed at a median younger age than non-Hispanic Whites. Permutation-based ANCOVA identified race/ethnicity and health insurance as significantly associated with age of diagnosis (P=0.001). Logistic regression selected (younger) age at diagnosis as being significantly associated with stage IV disease. The limitations of the case study reside in the use of self-reporting of race and ethnicity and in the small sample sizes. CONCLUSIONS: Hispanics may be at higher risk for colorectal cancer (<50>y) and younger age at diagnosis is associated with advanced disease.

Nitric oxide-donating aspirin induces G2/M phase cell cycle arrest in human cancer cells by regulating phase transition proteins.

NO-aspirin (NO-ASA), consisting of aspirin and a nitric oxide-releasing group, is safer than aspirin and effective in colon cancer prevention. Here, we examined the mechanism of action of NO-ASA by focusing primarily on its effects on the cell cycle. NO-ASA reduced the growth of several cell lines from colon, pancreas, skin, cervix and breast cancer much more potently than aspirin, with 24-h IC(50) values of 133-268 µM, while those of ASA were >1,000 µM. NO-ASA elevated the intracellular levels of reactive oxygen species, generating a state of oxidative stress. In all cell lines examined, NO-ASA induced cell cycle arrest in the G(2)/M phase transition accompanied by altered expression of G(2)/M transition-related proteins. In SW480 colon cancer cells NO-ASA modulated proteins controlling this transition. Thus, it markedly increased the levels of cyclin B1, decreased the expression of cyclin D1 and Cdc25C, and increased the Thr14/Tyr15-phosphorylation of Cdk1 while leaving unchanged its protein levels. These changes, including the G2/M arrest, were prevented by pretreating the cells with the anti-oxidant N-acetyl-cysteine, indicating that redox signaling is likely responsible for the cell cycle changes, a conclusion consistent with the known redox regulation of these proteins. Collectively, these results confirm the profound cytokinetic effect of NO-ASA and provide strong evidence that it regulates cell cycle transitions through its ability to induce oxidative stress, which activates redox signaling in the target cell.

Protein nitration and nitrosylation by NO-donating aspirin in colon cancer cells: Relevance to its mechanism of action.

Nitric oxide-donating aspirin (NO-ASA) is a promising agent for cancer prevention. Although studied extensively, its molecular targets and mechanism of action are still unclear. S-nitrosylation of signaling proteins is emerging as an important regulatory mechanism by NO. Here, we examined whether S-nitrosylation of the NF-κB, p53, and Wnt signaling proteins by NO-ASA might explain, in part, its mechanism of action in colon cancer. NO-ASA releases significant amounts of NO detected intracellularly in HCT116 and HT-29 colon cells. Using a modified biotin switch assay we demonstrated that NO-ASA S-nitrosylates the signaling proteins p53, ß-catenin, and NF-κB, in colon cancer cells in a time- and concentration-dependent manner. NO-ASA suppresses NF-κB binding to its cognate DNA oligonucleotide, which occurs without changes in the nuclear levels of the NF-κB subunits p65 and p50 and is reversed by dithiothreitol that reduces -S-NO to -SH. In addition to S-nitrosylation, we documented both in vitro and in vivo widespread nitration of tyrosine residues of cellular proteins in response to NO-ASA. Our results suggest that the increased intracellular NO levels following treatment with NO-ASA modulate cell signaling by chemically modifying key protein members of signaling cascades. We speculate that S-nitrosylation and tyrosine nitration are responsible, at least in part, for the inhibitory growth effect of NO-ASA on cancer cell growth and that this may represent a general mechanism of action of NO-releasing agents.

Functional characterization of peroxisome proliferator-activated receptor-ß/δ expression in colon cancer.

This study critically examined the role of PPARß/δ in colon cancer models. Expression of PPARß/δ mRNA and protein was lower and expression of CYCLIN D1 protein higher in human colon adenocarcinomas compared to matched non-transformed tissue. Similar results were observed in colon tumors from Apc(+/Min-FCCC) mice compared to control tissue. Dietary administration of sulindac to Apc(+/Min-FCCC) mice had no influence on expression of PPARß/δ in normal colon tissue or colon tumors. Cleaved poly (ADP-ribose) polymerase (PARP) was either increased or unchanged, while expression of 14-3-3ε was not influenced in human colon cancer cell lines cultured with the PPARß/δ ligand GW0742 under conditions known to increase apoptosis. While DLD1 cells exhibited fewer early apoptotic cells after ligand activation of PPARß/δ following treatment with hydrogen peroxide, this change was associated with an increase in late apoptotic/necrotic cells, but not an increase in viable cells. Stable over-expression of PPARß/δ in human colon cancer cell lines enhanced ligand activation of PPARß/δ and inhibition of clonogenicity in HT29 cells. These studies are the most quantitative to date to demonstrate that expression of PPARß/δ is lower in human and Apc(+/Min-FCCC) mouse colon tumors than in corresponding normal tissue, consistent with the finding that increasing expression and activation of PPARß/δ in human colon cancer cell lines inhibits clonogenicity. Because ligand-induced attenuation of early apoptosis can be associated with more late, apoptotic/necrotic cells, but not more viable cells, these studies illustrate why more comprehensive analysis of PPARß/δ-dependent modulation of apoptosis is required in the future.

Regulation of peroxisome proliferator-activated receptor-beta/delta by the APC/beta-CATENIN pathway and nonsteroidal antiinflammatory drugs.

Studies indicate that peroxisome proliferator-activated receptor-beta/delta (PPAR beta/delta) can either attenuate or potentiate colon cancer. One hypothesis suggests that PPAR beta/delta is upregulated by the adenomatous polyposis coli (APC)/beta-CATENIN pathway and a related hypothesis suggests that PPAR beta/delta is downregulated by nonsteroidal antiinflammatory drugs (NSAIDs). The present study examined these possibilities using in vivo and in vitro models. While APC/beta-CATENIN-dependent expression of CYCLIN D1 was observed in vivo and in vitro, expression of PPAR beta/delta was not different in colon or intestinal polyps from wild-type or Apc(min) heterozygous mice or in human colon cancer cell lines with mutations in APC and/or beta-CATENIN. No difference in the level of PPAR beta/delta was found in colon from wild-type or Apc(min) heterozygous mice following treatment with NO-donating aspirin (NO-ASA). NSAIDs inhibited cell growth in RKO (wild-type APC) and DLD1 (mutant APC) human colon cancer cell lines but expression of PPAR beta/delta was not downregulated in these cell lines in response to a broad concentration range of celecoxib, indomethacin, NS-398, or nimesulide. However, indomethacin caused an increase in PPAR beta/delta mRNA and protein that was accompanied with increased expression of a known PPAR beta/delta target gene. Interestingly, expression of PPAR alpha was also increased in the human colon cancer cell lines by several NSAIDs at the highest concentration examined. Results from these studies provide additional evidence indicating that PPAR beta/delta is not upregulated by the APC/beta-CATENIN pathway. Further, these studies suggest that increased PPAR beta/delta and/or PPAR alpha by NSAIDs in human colon cancer cell lines could contribute to the mechanisms underlying the chemopreventive effects of NSAIDs.