Insulin-like growth factors are more effective than progastrin in reversing proapoptotic effects of curcumin: critical role of p38MAPK

Investigating the potential role of swertiamarin on insulin resistant and non-insulin resistant granulosa cells of poly cystic ovarian syndrome patients

BACKGROUND AND AIM

Conventional drugs have limitations due to prevalence of contraindications in PCOS patients. To explore the potential effects of swertiamarin, on abrupted insulin and steroidogenic signaling in human luteinized granulosa cells from PCOS patients with or without insulin resistance.

EXPERIMENTAL PROCEDURE

hLGCs from 8 controls and 16 PCOS patients were classified for insulin resistance based on down regulation of protein expression of insulin receptor-β (INSR- β) as shown in our previous paper. Cells were grouped as control, PCOS-IR and PCOS-NIR, treated with swertiamarin (66 µM) and metformin (1 mM). Expression of key molecules involved in insulin signaling, fat metabolism, IGF system and steroidogenesis were compared between groups.

RESULTS

Swertiamarin significantly (P < 0.05) reversed the expression of INSR-β, PI(3)K, p-Akt, PKC-ζ, PPARγ, (P < 0.01) IRS (Ser 307) and IGF system in PCOS-IR group and was equally potent to metformin. In the same group, candidate genes viz SREBP1c, FAS, ACC-1 and CPT-1 were down regulated by swertiamarin (P < 0.001) and metformin (P < 0.001). Significant upregulation was demonstrated in expression of StAR, CYP19A1, 17β-HSD and 3β-HSD when treated with swertiamarin (P < 0.01) and metformin (P < 0.01) in PCOS-IR followed by increase in 17β-HSD and 3β-HSD enzyme activity along with estradiol and progesterone secretions. However, swertiamarin did not reveal any effect on PCOS-NIR group as compared to metformin that significantly (P < 0.01) reversed all the parameters related to steroidogenesis and down regulated basal expression of insulin signaling genes.

CONCLUSION

Swertiamarin, presents itself as a potential fertility drug in hLGCs from PCOS-IR patients.

Ophiopogonin D inhibits cell proliferation and induces apoptosis of human laryngocarcinoma through downregulation of cyclin B1 and MMP-9 and upregulation of p38-MAPK signaling

The pharmacological actions of Ophiopogonin D include resistance to cardiovascular and cerebrovascular diseases, anti-aging effects, improvement in learning deficit and dysmnesia, anti-tumor, anti-radiation and anti-inflammatory effects, immunoregulation, and the relief of cough and hepatopulmonary pathological lesions. However, the efficacy of Ophiopogonin D on human laryngocarcinoma remains to be elucidated. The present study therefore investigated whether the anti-cancer effect of Ophiopogonin D inhibits cell proliferation and induces apoptosis of human laryngocarcinoma. In the present study, it was found that Ophiopogonin D inhibited cell proliferation, promoted cytotoxicity, induced apoptosis and increased caspase-3/9 activity in human laryngocarcinoma cells. Ophiopogonin D significantly suppressed cyclin B1 and matrix metalloproteinase-9 (MMP-9) protein expression, and upregulated p-p38 MAPK protein expression in human laryngocarcinoma cells. Together, these results suggest Ophiopogonin D inhibits cell proliferation and induced apoptosis in human laryngocarcinoma cells through downregulation of cyclin B1 and MMP-9 and upregulation of the p38 MAPK signaling pathway. Therefore, Ophiopogonin D may be a potential therapy for the treatment of human laryngocarcinoma.

Epigenetic regulation of human DCLK-1 gene during colon-carcinogenesis: clinical and mechanistic implications

Colorectal carcinogenesis is a multi-step process. While ~25% of colorectal cancers (CRCs) arise in patients with a family history (genetic predisposition), ~75% of CRCs are due to age-associated accumulation of epigenetic alterations which can result in the suppression of key tumor suppressor genes leading to mutations and activation of oncogenic pathways. Sporadic colon-carcinogenesis is facilitated by many molecular pathways of genomic instability which include chromosomal instability (CIN), micro-satellite instability (MSI) and CpG island methylator phenotype (CIMP), leading towards loss of homeostasis and onset of neoplastic transformation. The unopposed activation of Wnt/β-catenin pathways, either due to loss of APC function or up-regulation of related stimulatory pathways, results in unopposed hyperproliferation of colonic crypts, considered the single most important risk factor for colon carcinogenesis. Hypermethylation of CpG islands within the promoters of specific genes can potentially inactivate DNA repair genes and/or critical tumor suppressor genes. Recently, CpG methylation of the 5' promoter of human (h) DCLK1 gene was reported in many human epithelial cancers, including colorectal cancers (CRCs), resulting in the loss of expression of the canonical long isoform of DCLK1 (DCLK1-L) in hCRCs. Instead, a shorter isoform of DCLK1 (DCLK1-S) was discovered to be expressed in hCRCs, from an alternate β promoter of DCLKL1-gene; the clinical and biological implications of these novel findings, in relation to recent publications is discussed.

Curcumin promotes autophagic survival of a subset of colon cancer stem cells, which are ablated by DCLK1-siRNA

Curcumin is known to induce apoptosis of cancer cells by different mechanisms, but its effects on cancer stem cells (CSC) have been less investigated. Here, we report that curcumin promotes the survival of DCLK1-positive colon CSCs, potentially confounding application of its anticancer properties. At optimal concentrations, curcumin greatly reduced expression levels of stem cell markers (DCLK1/CD44/ALDHA1/Lgr5/Nanog) in three-dimensional spheroid cultures and tumor xenografts derived from colon cancer cells. However, curcumin unexpectedly induced proliferation and autophagic survival of a subset of DCLK1-positive CSCs. Spheroid cultures were disintegrated by curcumin in vitro but regrew within 30 to 40 days of treatment, suggesting a survival benefit from autophagy, permitting long-term persistence of colorectal cancer. Notably, RNA interference-mediated silencing of DCLK1 triggered apoptotic cell death of colon cancer cells in vitro and in vivo, and abolished colorectal cancer survival in response to curcumin; combination of DCLK1-siRNA and curcumin dramatically reversed CSC phenotype, contributing to attenuation of the growth of spheroid cultures and tumor xenografts. Taken together, our findings confirm a role of DCLK1 in colon CSCs and highlight DCLK1 as a target to enhance antitumor properties of curcumin.

Progastrin Peptides Increase the Risk of Developing Colonic Tumors: Impact on Colonic Stem Cells

Pre-neoplastic lesions (ACF, aberrant-crypt-foci; Hp, hyperplastic/dysplastic polyps) are believed to be precursors of sporadic colorectal-tumors (Ad, adenomas; AdCA, adenocarcinomas). ACF/Hp likely originate due to abnormal growth of colonic-crypts in response to aberrant queues in the microenvironment of colonic-crypts. Thus identifying factors which regulate homeostatic vs aberrant proliferation/apoptosis of colonocytes, especially stem/progenitor cells, may lead to effective preventative/treatment strategies. Based on this philosophy, role of growth-factors/peptide-hormones, potentially available in the circulation/microenvironment of colonic-crypts is being examined extensively. Since the time gastrins were discovered as trophic (growth) factors for gastrointestinal-cells, the effect of gastrins on the growth of normal/cancer cells has been investigated, leading to many discoveries. Seminal discoveries made in the area of gastrins and colon-cancer, as it relates to molecular pathways associated with formation of colonic tumors will be reviewed, and possible impact on diagnostic/preventative/treatment strategies will be discussed.

Progastrin overexpression imparts tumorigenic/metastatic potential to embryonic epithelial cells: phenotypic differences between transformed and nontransformed stem cells

We recently reported that overexpression of progastrin (PG) in embryonic epithelial cells (HEKmGAS cells) increased proliferation of the cells compared to that of control HEKC cells. Here, we report the novel finding that tumorigenic and metastatic potential of HEKmGAS cells is also increased significantly compared to that of HEKC cells. Cell surface-associated annexinA2 (CS-ANXA2) binds PG and is overexpressed on cancer cells, allowing us to successfully use fluorescently labeled PG peptide for enumerating metastatic lesions of transformed/cancer cells in vivo. Next, we examined the hypothesis that increased tumorigenic/metastatic potential of isogenic HEKmGAS versus HEKC cells maybe due to transformed phenotype of stem cells. FACSorting/FACScanning of cells demonstrated significant increases in percent doublecortin-CAM-kinase-like1 (DCLK1)/Lgr5-positive stem cells, coexpressing cluster of differentiation44 (CD44)/CS-ANXA2, in HEKmGAS versus HEKC cells. Distinct differences were noted in the morphology of HEKC versus HEKmGAS spheroidal growths on nonadherent cultures (selective for stem cells). HEKC spheroids were rounded with distinct perimeters (e.g., basement membranes), whereas HEKmGAS spheroids were amorphous with no perimeters. Relative levels of DCLK1/Lgr5/CD44 and ANXA2/β-catenin/pNFκBp65/metalloproteinases were significantly increased in HEKmGAS versus HEKC cells, growing as monolayer cultures, 3D spheroids (in vitro), or xenografts (in vivo). Interestingly, HEKC cells enriched for CS-ANXA2 developed amorphous spheroids, whereas downregulation of ANXA2 in HEKmGAS clones resulted in loss of matrixmetalloproteinases (MMPs) and re-formation of rounded spheroids, suggesting that high levels of CS-ANXA2/MMPs may impact spheroid morphology. Downregulation of DCLK1 significantly attenuated activation of β-catenin, with loss of proliferation of HEKmGAS and HEKC cells, suggesting that DCLK1 is required for maintaining proliferation of cells. Our results suggest the novel possibility that transformed stem cells, unlike nontransformed stem cells, coexpress stem cell markers DCLK1 and CD44 with CS-ANXA2.

Curcumin molecular targets in obesity and obesity-related cancers

Obesity is characterized as an increased BMI, which is associated with the increased risk of several common cancers, including colorectal, breast, endometrial, renal, esophageal, gallbladder, melanoma, multiple myeloma, leukemia, lymphoma and prostate cancer. The increased risk of obesity-related cancers could be mediated by insulin resistance, adipokines, obesity-related inflammatory cytokines, sex hormones, transcription factors and oxidative stress, which disrupt the balance between cell proliferation and apoptosis. The yellowish compound, curcumin (diferuloylmethane), is known to possess multifaceted pharmacological effects. The molecular mechanisms linking obesity to cancer risk, and how curcumin mediates anticancer and obesity activities, have not yet been publicized. Curcumin modulates multiple molecular targets and reverses insulin resistance as well as other symptoms that are associated with obesity-related cancers. In this study, we show that ample evidence exists to support recommendations that curcumin mediates multiple molecular pathways, and is considered to be of therapeutic value in the treatment and prevention of obesity-related cancers.

Annexin A2 mediates up-regulation of NF-κB, β-catenin, and stem cell in response to progastrin in mice and HEK-293 cells

BACKGROUND & AIMS

Prograstrin induces proliferation in colon crypts by activating p65nuclear factor-κB (NF-κB) (p65) and β-catenin. We investigated whether Annexin A2 (AnxA2), a progastrin receptor, activates NF-κB and β-catenin in vivo.

METHODS

ANXA2-null (ANXA2(-/-)) and wild-type (ANXA2(+/+)) mice were studied, along with clones of progastrin-responsive HEK-293 cells that stably expressed full-length progastrin (HEK-mGAS) or an empty vector (HEK-C). Small interfering RNA was used to down-regulate AnxA2, p65NF-κB, and β-catenin in cells.

RESULTS

Proliferation and activation of p65 and β-catenin increased significantly in HEK-mGAS compared with HEK-C clones. HEK-mGAS cells had a 2- to 4-fold increase in relative levels of c-Myc, cyclooxygenase (COX)-2, CyclinD1, double cortin CAM kinase-like 1 (DCAMKL+1), and CD44, compared with HEK-C clones. Down-regulation of AnxA2 in HEK-mGAS clones reduced activation of NF-κB and β-catenin, as well as levels of DCAMKL+1. Surprisingly, down-regulation of β-catenin had no effect on activation of p65NF-κB, whereas down-regulation of p65 significantly reduced activation of β-catenin in HEK-mGAS clones. Loss of either p65 or β-catenin significantly reduced proliferation of HEK-mGAS clones, indicating that both factors are required for the proliferative effects of progastrin. Lengths of colon crypts and levels of p65, β-catenin, DCAMKL+1, and CD44 were significantly higher in ANXA2(+/+) mice compared with either ANXA2(-/-) mice given progastrin or ANXA2(+/+) and ANXA2(-/-) mice given saline.

CONCLUSIONS

AnxA2 expression is required for the biologic effects of progastrin in vivo and in vitro and mediates the stimulatory effect of progastrin on p65NF-κ, β-catenin, and the putative stem cell markers DCAMKL+1 and CD44. AnxA2 might therefore mediate the hyperproliferative and cocarcinogenic effects of progastrin.