Mortality in patients with alpha-mannosidosis: a review of patients' data and the literature.

BACKGROUND: Alpha-mannosidosis is a rare autosomal recessive lysosomal storage disorder (LSD) caused by reduced activity of alpha-mannosidase. Clinical manifestations include skeletal dysmorphism, mental impairment, hearing loss and recurrent infections. The severe type of the disease leads to early childhood death, while patients with milder forms can live into adulthood. There are no mortality studies to date. This study aimed to investigate the age at death and the causes of death of patients with alpha-mannosidosis who had not received disease-modifying treatment. METHODS: Clinicians and LSD patient organisations (POs) from 33 countries were invited to complete a questionnaire between April-May 2021. Cause of death and age at death was available for 15 patients. A literature review identified seven deceased patients that met the inclusion criteria. RESULTS: Median age at death for patients reported by clinicians/POs was 45 years (mean 40.3 ± 13.2, range 18-56, n = 15); 53% were female. One death occurred during the patient's second decade of life, and 14 out of 15 deaths (93.3%) during or after the patients' third decade, including four (26.7%) during their sixth decade. Median age at death for patients identified from the literature was 4.3 years (mean 15.7 ± 17.0, range 2.2-41, n = 7); two were female. Four of the seven patients (57.1%) died within the first decade of life. Seven of 15 deaths (46.7%) reported by clinicians/POs were recorded as pneumonia and three (20.0%) as cancer. Other causes of death included acute renal failure due to sepsis after intestinal perforation, decrease of red blood cells of unknown origin, kidney failure with systemic lupus erythematosus, aortic valve insufficiency leading to heart failure, and dehydration due to catatonia. Three out of seven causes of death (42.9%) reported in the literature were associated with septicaemia, two (28.6%) with respiratory failure and one to pneumonia following aspiration. CONCLUSIONS: This study suggests that pneumonia has been the primary cause of death during recent decades in untreated patients with alpha-mannosidosis, followed by cancer. Determining the causes of mortality and life expectancy in these patients is crucial to further improve our understanding of the natural history of alpha-mannosidosis.

Poly(ADP-ribosylation) and neoplastic transformation: effect of PARP inhibitors.

Poly(ADP-ribose) polymerases (PARPs) and poly(ADP-ribosylation) play essential roles in several biological processes, among which neoplastic transformation and telomere maintenance. In this paper, we review the poly(ADP-ribosylation) process together with the highly appealing use of PARP inhibitors for the treatment of cancer. In addition, we report our results concerning poly(ADP-ribosylation) in a cellular model system for neoplastic transformation developed in our laboratory. Here we show that PARP-1 and PARP-2 expression increases during neoplastic transformation, together with the basal levels of poly(ADP-ribosylation). Furthermore, we demonstrate a greater effect of the PARP inhibitor 3-aminobenzamide (3AB) on cellular viability in neoplastically transformed cells compared to normal fibroblasts and we show that prolonged 3AB administration to tumorigenic cells causes a decrease in telomere length. Taken together, our data support an active involvement of poly(ADP-ribosylation) in neoplastic transformation and telomere length maintenance and confirm the relevant role of poly(ADP-ribosylation) inhibition for the treatment of cancer.

Drug treatment of cancer cell lines: a way to select for cancer stem cells?

Tumors are generally composed of different cell types. In recent years, it has been shown that in many types of cancers a subset of cells show peculiar characteristics, such as the ability to induce tumors when engrafted into host animals, self-renew and being immortal, and give rise to a differentiated progeny. These cells have been defined as cancer stem cells (CSCs) or tumor initiating cells. CSCs can be isolated both from tumor specimens and established cancer cell lines on the basis of their ability to exclude fluorescent dyes, express specific cell surface markers or grow in particular culture conditions. A key feature of CSCs is their resistance to chemotherapeutic agents, which could contribute to the remaining of residual cancer cells after therapeutic treatments. It has been shown that CSC-like cells can be isolated after drug treatment of cancer cell lines; in this review, we will describe the strategies so far applied to identify and isolate CSCs. Furthermore, we will discuss the possible use of these selected populations to investigate CSC biology and develop new anticancer drugs.

2-Methoxyestradiol: new perspectives in colon carcinoma treatment.

Colon carcinoma represents a major problem in oncology, since this type of cancer responds poorly to conventional chemotherapy. Many groups are actively involved in the search of new experimental strategies to bypass this problem. We investigated the effects of 2-methoxyestradiol (2-ME), which derives from the NADPH-dependent cytochrome P450 metabolism of 17ß-estradiol. This compound has raised much interest in the past few decades for its inhibitory effects on the growth of cancer cells of different origin; however, little is known about its use on colon carcinoma-derived cell lines. In the present study, we investigated the effects of 2-ME on cell proliferation and cell cycle of two human colon carcinoma cell lines, namely HCT116 and SW613-B3. Our results showed a net anti-proliferative effect of 2-ME on both cell lines, which is accompanied by cell cycle arrest; moreover, we demonstrated that 2-ME is able to induce apoptosis as well as autophagy. This body of evidence points out that 2-ME could be considered as a promising tool against colon carcinoma.

PARP inhibitors: new tools to protect from inflammation.

Poly(ADP-ribosylation) consists in the conversion of ß-NAD(+) into ADP-ribose, which is then bound to acceptor proteins and further used to form polymers of variable length and structure. The correct turnover of poly(ADP-ribose) is ensured by the concerted action of poly(ADP-ribose) polymerase (PARP) and poly(ADP-ribose) glycohydrolase (PARG) enzymes, which are responsible for polymer synthesis and degradation, respectively. Despite the positive role of poly(ADP-ribosylation) in sensing and repairing DNA damage, generated also by ROS, PARP over-activation could allow NAD depletion and consequent necrosis, thus leading to an inflammatory condition in many diseases. In this respect, inhibition of PARP enzymes could exert a protective role towards a number of pathological conditions; i.e. the combined treatment of tumors with PARP inhibitors/anticancer agents proved to have a beneficial effect in cancer therapy. Thus, pharmacological inactivation of poly(ADP-ribosylation) could represent a novel therapeutic strategy to limit cellular injury and to attenuate the inflammatory processes that characterize many disorders.

p21CDKN1A participates in base excision repair by regulating the activity of poly(ADP-ribose) polymerase-1.

The cell cycle inhibitor p21(CDKN1A) has been shown to participate in nucleotide excision repair by interacting with PCNA. Here we have investigated whether p21 plays a role in base excision repair (BER), by analyzing p21 interactions with BER factors, and by assessing the response of p21(-/-) human fibroblasts to DNA damage induced by alkylating agents. Absence of p21 protein resulted in a higher sensitivity to alkylation-induced DNA damage, as indicated by reduced clonogenic efficiency, defective DNA repair (assessed by the comet test), and by persistence of histone H2AX phosphorylation. To elucidate the mechanisms at the basis of the function of p21 in BER, we focused on its interaction with poly(ADP-ribose) polymerase-1 (PARP-1), an important player in this repair process. p21 was found to bind the automodification/DNA binding domain of PARP-1, although some interaction occurred also with the catalytic domain after DNA damage. This association was necessary to regulate PARP-1 activity since poly(ADP-ribosylation) induced by DNA damage was higher in p21(-/-) human fibroblasts than in parental p21(+/+) cells, and in primary fibroblasts after p21 knock-down by RNA interference. Concomitantly, recruitment of PARP-1 and PCNA to damaged DNA was greater in p21(-/-) than in p21(+/+) fibroblasts. This accumulation resulted in persistent interaction of PARP-1 with BER factors, such as XRCC1 and DNA polymerase beta, suggesting that prolonged association reduced the DNA repair efficiency. These results indicate that p21 regulates the interaction between PARP-1 and BER factors, to promote efficient DNA repair.

Loss of histone H2AX increases sensitivity of immortalized mouse fibroblasts to the topoisomerase II inhibitor etoposide.

In mammalian cells, the H2AX histone is rapidly phosphorylated upon the induction of DNA double strand breaks and promotes their repair, which is required for preserving genomic integrity. Etoposide is an inhibitor of DNA topoisomerase II, which causes DNA breaks and induces H2AX phosphorylation. To elucidate whether H2AX may affect cellular sensitivity to etoposide, we studied the response to this agent in immortalized embryonic fibroblasts derived from H2AX knockout mice. Clonogenic assays in cells treated with the drug revealed a greater sensitivity of H2AX null cells compared to wild-type cells, possibly due to the persistence of a higher number of DNA breaks, as detected with the comet assay. In both cell lines, etoposide induced micronuclei formation and nuclear fragmentation; however, in H2AX deficient cells nuclear fragmentation was observed at a lower drug concentration. Flow cytometric analysis showed that etoposide induced a G2/M cell cycle arrest in both cell lines, which occurred at lower drug concentrations in H2AX deficient cells. G2/M arrest was paralleled by an accumulation of cyclin A and cyclin B1, suggesting that treated cells are not able to complete cell cycle correctly and undergo cell death. Taken together, our observations suggest that H2AX takes part to the cellular response to etoposide and confirm its role in the maintenance of genome stability.