Natale D'Alessandro

Sex Hormones and Risk of Liver Tumor

Abstract:  The liver is morphologically and functionally modulated by sex hormones. Long‐term use of oral contraceptives (OCs) and anabolic androgenic steroids (AASs) can induce both benign (hemangioma, adenoma, and focal nodular hyperplasia [FNH]) and malignant (hepatocellular carcinoma [HCC]) hepatocellular tumors. Hepatic adenomas (HAs) are rare, benign neoplasms usually occurring in young women, the development and the complications of which have been related to the strength of OCs and the duration of their use. HA incidence has fallen since the introduction of pills containing smaller amounts of estrogens. FNH is a benign lesion, most commonly seen in young women, which is thought to represent a local hyperplastic response of hepatocytes to a vascular abnormality. Because of the female predominance and the young age at onset, a role of female hormones has been suggested. Furthermore, a large proportion of women with FNH (50–75%) are OC users. Liver hemangiomas (LHs) are the most common benign liver tumors and are seen more commonly in young adult females. The female predilection and clinical observations of LH growth under conditions of estrogenic exposure suggest a possible role for estrogen in the pathogenesis of LHs. HCC has become one of the most widespread tumors in the world in recent years, representing the sixth leading cancer and the third most common cause of death from cancer. Apart from liver cirrhosis, numerous other factors responsible for its onset have been proposed: hepatitis infections from virus B (HBV) and C (HCV), alcohol, smoking, and aflatoxin. However, regardless of etiology, chronic liver diseases progress at unequal rates in the two sexes, with the major sequelae, such as cirrhosis and HCC, being more frequent in men than in women. These epidemiological data have prompted researchers to investigate the relationship between sex hormones and liver tumors. The human liver expresses estrogen and androgen receptors and experimentally both androgens and estrogens have been implicated in stimulating hepatocyte proliferation and may act as liver tumor inducers or promoters.

Resistance to diverse apoptotic triggers in multidrug resistant HL60 cells and its possible relationship to the expression of P-glycoprotein, Fas and of the novel anti-apoptosis factors IAP (inhibitory of apoptosis proteins)

We studied the human HL60 leukemia cell line and its multidrug resistant (MDR) variant HL60R. In contrast to the HL60, HL60R showed an inability to undergo apoptosis from doxorubicin (Dox) or other different stimuli, including cisplatin, Fas ligation and serum withdrawal. HL60R cells lost surface Fas expression, but we found no evidence that Fas/FasL mediates the apoptotic effects of Dox in HL60. P-glycoprotein (P-gp) did not seem to play a major role as a specific inhibitor of apoptosis. In fact, the P-gp inhibitor verapamil reversed only partially the resistance to Dox-induced apoptosis of the MDR cells. In addition, it did not modify the rate of apoptosis induced from the other stimuli in the same cells. The expression of p53 or Bcl-2 was not different between HL60 and HL60R. However, in HL60R there was an increase in the mRNAs of inhibitory of apoptosis proteins (IAPs) like neuronal apoptosis inhibitory protein (NAIP), c-IAP-2 and survivin. Treatment with Dox or serum starvation strongly down-regulated X-linked IAP and survivin mRNAs in HL60. Cisplatin decreased NAIP and survivin mRNAs in the same cells. However, in HL60R the levels of these IAP mRNAs were much less affected by the treatments. These results support that IAPs may be involved in tumor resistance to chemotherapeutic drugs or other apoptotic agents.

The CD95/CD95 ligand system is not the major effector in anticancer drug-mediated apoptosis

Many anticancer drugs are able to induce apoptosis in tumor cells but the mechanisms underlying this phenomenon are poorly understood. Some authors reported that the p53 tumor suppressor gene may be responsible for drug-induced apoptosis; however, chemotherapy-induced apoptosis can also be observed in p53 negative cells. Recently, doxorubicin (DXR) was reported to induce CD95L expression to mediate apoptosis through the CD95/CD95L system. Thus, an impairment of such a system may be involved in drug resistance. We evaluated the in vitro antitumor activity of several cytotoxic drugs on two human p53-negative T-cell lymphoma cell lines, the HUT78-B1 CD95L-resistant cell line and the HUT78 parental CD95L-sensitive cell line. We demostrated by Western blotting assay that DXR and etoposide (VP-16) were able to induce CD95L expression after 4 h of treatment. In contrast, they were unable to induce the expression of p53. DXR, at concentrations ranging from 0.001–1 μg/ml, and VP16, at concentrations ranging from 0.05–1 μg/ml, were equally cytotoxic and induced apoptosis in both cell lines as assessed by fluorescence microscopy and flow cytometry analyses. Although we observed a slightly reduced percentage of apoptotic cells in HUT78B1 when compared with the parental HUT78 cells after few hours of drug exposure, this difference was no longer evident at 48 or 72 h. Similarly, the exposure of HUT78 cells to a CD95-blocking antibody partially reduced early apoptosis (24 h) without affecting the long-term effects of the drugs including cytotoxicity. Furthermore, as observed with DXR and VP-16, both the CD95L-sensitive and the CD95L-resistant cell lines resulted equally sensitive to the cytotoxic effects of a number of different cytotoxic drugs (vincristine, camptothecin, 5-fluorouracil and methotrexate). The treatment with the Caspase-3 tetrapeptide aldehyde inhibitor, Ac-DEVD-CHO, did not affect the DXR-induced apoptosis whereas it only modestly inhibited apoptosis and cytotoxicity of VP-16, while Z-VAD.FMK, a Caspase inhibitor that prevents the processing of Caspase-3 to its active form, was able to block DXR-induced apoptosis at 24 h but not at 48 h. Thus, our results do not confirm a crucial role for the CD95/CD95L system in drug-induced apoptosis and suggest the involvement of alternative p53-independent pathways at least in this experimental model system.

Circulating IL-6 and sIL-6R in Patients with Hepatocellular Carcinoma

Abstract: Interleukin‐6 plays a central role in regulating the immune system, hematopoiesis, and acute phase reaction. It interacts with a receptor complex consisting of a specific ligand‐binding protein (IL‐6R, gp80) and a signal transduction protein (gp130). In this report, serum levels of IL‐6 and a soluble form of the interleukin‐6 receptor (sIL‐6R) were evaluated in patients with hepatocellular carcinoma. The correlation between IL‐6 and sIL‐6R values, the stage of hepatocellular carcinoma, and main liver function tests was also studied.

Retinoic acid and analogs as potent inducers of differentiation and apoptosis. New promising chemopreventive and chemotherapeutic agents in oncology

In this report we will describe the preparation and the biological activity of a novel class of heterocyclic arotinoids endowed with potent cytotoxic and apoptotic acitivity. Structureactivity relationship studies revealed that the different stereochemistry at the C9 double bond of retinoids seems associated with a different biological activity: potent apoptotic activity for the cis-isomers, whereas differentiating activity for the trans structures. An interesting modified Wittig procedure that allows easily to arotinoids will also be described. The substitution of the alkenyl portion with a more flexible oxymethyl or aminomethyl moiety gave compounds with poor activity, whereas isoxazole-bridged arotinoids allowed compounds active also on multidrug-resistant (MDR) leukemia cell lines.

Expression of WISPs and of their novel alternative variants in human hepatocellular carcinoma cells.

Abstract: WISPs (Wnt‐induced secreted proteins) are members of the CCN (CTGF/Cyr61/Nov) family involved in fibrotic disorders and tumorigenesis. They have a typical structure composed of four conserved cysteine‐rich modular domains, but variants of CCN members lacking one or more modules, generated by alternative splicing or gene mutations, have been described in various pathological conditions. WISP genes were first described as downstream targets of the Wnt signaling pathway, which is frequently altered in human hepatocellular carcinoma (HCC). In the present study, WISP mRNA expression was analyzed by RT‐PCR in four human HCC cell lines (HepG2, HuH‐6, HuH‐7, HA22T/VGH). Our results show for the first time that WISP1, WISP1v, and WISP3 are expressed in HCC cell lines. Moreover, we identified two novel variants, generated by alternative splicing of WISP1 and WISP3, respectively, named WISP1Δex3‐4 and WISP3vL. Overall, our study suggests that WISP transcripts may have a role in the development of HCC, although further studies are necessary to clarify the relative importance of the expression of wild‐type WISPs, as well as of their novel variants, in this tumor type.

Induction of Apoptosis and Inhibition of Cell Growth in Human Hepatocellular Carcinoma Cells by COX‐2 Inhibitors

Abstract: The aim of the present study was to examine the effects of nonselective (indomethacin) and selective cyclooxygenase‐2 (COX‐2) inhibitors (NS‐398, nimesulide, and CAY10404) on cell growth, cell cycle distribution, and apoptosis in three human hepatocellular carcinoma cell lines (HepG2, HuH‐6, and HA22T/VGH) with different characteristics of differentiation and biological behavior. The four COX inhibitors showed a dose‐dependent growth‐inhibitory effect in all the cell lines. No substantial arrests in the progression of the cells through the cell cycle were observed after treatment of HuH‐6 or HA22T/VGH for 48 h with the various inhibitors. On the other hand, there were significant increases in apoptosis, with the highest effect of cell kill being seen after treatment with indomethacin, especially in HuH‐6. Our findings support the suggestion that selective or, perhaps more efficiently, nonselective COX‐2 inhibitors may have potential therapeutic effects in hepatocellular carcinoma. Further studies must be carried out to better determine the possible mechanisms of these effects.

Curcumin as a Possible Lead Compound against Hormone‐Independent, Multidrug‐Resistant Breast Cancer

We examine the possible evidence that the phytochemical curcumin may overcome resistance to hormonal and cytotoxic agents in breast cancer. We present our observations on MCF‐7R, a multidrug‐resistant (MDR) variant of the MCF‐7 breast cancer cell line. In contrast to MCF‐7, MCF‐7R lacks aromatase and estrogen receptor α (ERα) and overexpresses the multidrug transporter ABCB1 and the products of different genes implicated in cell proliferation and survival, like c‐IAP‐1, NAIP, survivin, and COX‐2. Nevertheless, in cytotoxicity and cell death induction assays, we found that the antitumor activity of curcumin is substantial both in MCF‐7 and in MCF‐7R. We elaborated the diketone system of curcumin into different analogues; the benzyloxime and the isoxazole and pyrazole heterocycles showed remarkable increases in the antitumor potency both in the parental and in the MDR MCF‐7 cells. Furthermore, curcumin or, more potently, the isoxazole analogue, produced early reductions in the amounts of relevant gene transcripts that were diverse (i.e., they were relative to Bcl‐2 and Bcl‐XL in MCF‐7 and the inhibitory of apoptosis proteins and COX‐2 in MCF‐7R) in the two cell lines. Thus, the two compounds exhibited the remarkable property of being able to modify their molecular activities according to the distinct characteristics of the parental and MDR cells. We discuss also how curcumin may (1) exert antitumor effects in breast cancer through ER‐dependent and ER‐independent mechanisms; and (2) act as a drug transporter‐mediated MDR reversal agent. Overall, the structure of curcumin may represent the basis for the development of new, effective anticancer agents in hormone‐independent MDR breast cancer.

Antitumor Effects of Dehydroxymethylepoxyquinomicin, a Novel Nuclear Factor-κB Inhibitor, in Human Liver Cancer Cells Are Mediated through a Reactive Oxygen Species-Dependent Mechanism

Activation of the nuclear transcription factor-κB (NF-κB) has been implicated in liver tumorigenesis. We evaluated the effects of a novel NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), in two human liver cancer cell lines HA22T/VGH and HuH-6. DHMEQ treatment dose dependently decreased the DNA-binding capacity of the NF-κB p65 subunit, inhibited cell growth and proliferation, and increased apoptosis as shown by caspase activation, release of cytochrome c, poly(ADP-ribose) polymerase cleavage, and down-regulation of survivin. DHMEQ also induced a dose-dependent activation of mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling, and inhibition of this pathway significantly reduced cell growth. It is noteworthy that we observed that DHMEQ stimulated reactive oxygen species (ROS) production in a dose-dependent manner and that pretreatment of the cells with the antioxidant N-acetyl-l-cysteine (NAC) significantly reduced DHMEQ-induced ROS generation. Accordingly, NAC completely reversed the DHMEQ-induced growth inhibition, caspase activation, and cell death. DHMEQ-treated cells exhibited DNA damage, as evaluated by accumulation in nuclear foci of phospho-H2AX, which was completely reversed by NAC. Moreover, DHMEQ induced the expression of genes involved in the endoplasmic reticulum stress response (GRP78, CHOP, TRB3) and promoted the splicing of XBP1 mRNA in a dose-dependent fashion in both cell lines, which was reversed in the presence of NAC. Knockdown of TRB3 mRNA expression by small interference RNA significantly decreased DHMEQ-induced cell growth inhibition. These data suggest that DHMEQ antitumor effects are primarily mediated through ROS generation. Thereby, considering that cancer cells are under increased ER stress and oxidative stress conditions, DHMEQ may greatly improve various anticancer strategies.

Cyclooxygenase-2 Expression in Chronic Liver Diseases and Hepatocellular Carcinoma : An Immunohistochemical Study

Hepatocarcinogenesis is a multistep process characterized by hepatocyte inflammation, regeneration, and proliferation. These changes are believed to depend on the aberrant expression of various tumor suppressor genes, oncogenes and growth factors. Several studies have shown the involvement of cyclooxygenase‐2 (COX‐2), the inducible isoform of the enzymes that catalyze prostaglandin synthesis in various aspects of carcinogenesis. COX‐2 has been described as being overexpressed in hepatocellular carcinoma (HCC) patients. Using immunohistochemistry, we studied COX‐2 expression in different chronic liver diseases (CLD) including nonalcoholic steatohepatitis (NASH), chronic hepatitis (CH), liver cirrhosis (LC), and HCC in a population referred to a tertiary center in western Sicily, an area moderately endemic for CLD. Sixteen NASH, 35 CH, 15 LC, and 21 HCC samples were analyzed. Positive signs of COX‐2 were observed in the cytoplasm of hepatocytes and median values were 6 (3–9) for NASH, 7 (3–9) for CH, 6 (4–9) for LC, and 4 (0–7) for HCC. COX‐2 expression was significantly lower in HCC than in NASH (P < 0.001), CH (P < 0.0001), and LC (P < 0.0001). In HCC we found a wide range of COX‐2 expression: from no expression in poorly differentiated areas to a high expression in well‐differentiated ones, with an inverse correlation between COX‐2 and tumor grading, according to Edmonson (ρ=−0.67, P < 0.0001). In conclusion: (a) COX‐2 expression was significantly lower in HCC than in the other CLD; (b) COX‐2 expression inversely correlated with tumor differentiation status. These results suggest that COX‐2 expression could be related to the inflammatory phenomena present in the early phases of CLD and eventually to the induction of hepatocarcinogenesis.