A role for growth hormone and prolactin in leukaemia and lymphoma?

Oral immune-mediated disorders with malignant potential/association: An overview

A group of oral disorders or conditions, which may result from, or could be triggered by an abnormality in the normal immune response of an individual are known as oral immune-mediated disorders. Some of these disorders have malignant potential, while others are associated with malignancy. In this overview, we will discuss a few of the oral diseases (such as oral lichen planus, primary Sjogren's syndrome, systemic lupus erythematosus, dermatitis herpetiformis, and linear immunoglobulin A bullous dermatosis, to name a few), which are caused due to irregularity in the immune system and are either associated with malignancy or capable of undergoing malignant transforming, thereby increasing the morbidity and mortality rate.

Why are hematopoietic stem cells so 'sexy'? on a search for developmental explanation

Evidence has accumulated that normal human and murine hematopoietic stem cells express several functional pituitary and gonadal sex hormones, and that, in fact, some sex hormones, such as androgens, have been employed for many years to stimulate hematopoiesis in patients with bone marrow aplasia. Interestingly, sex hormone receptors are also expressed by leukemic cell lines and blasts. In this review, I will discuss the emerging question of why hematopoietic cells express these receptors. A tempting hypothetical explanation for this phenomenon is that hematopoietic stem cells are related to subpopulation of migrating primordial germ cells. To support of this notion, the anatomical sites of origin of primitive and definitive hematopoiesis during embryonic development are tightly connected with the migratory route of primordial germ cells: from the proximal epiblast to the extraembryonic endoderm at the bottom of the yolk sac and then back to the embryo proper via the primitive streak to the aorta-gonado-mesonephros (AGM) region on the way to the genital ridges. The migration of these cells overlaps with the emergence of primitive hematopoiesis in the blood islands at the bottom of the yolk sac, and definitive hematopoiesis that occurs in hemogenic endothelium in the embryonic dorsal aorta in AGM region.

Novel evidence that pituitary gonadotropins directly stimulate human leukemic cells-studies of myeloid cell lines and primary patient AML and CML cells

We recently reported that normal hematopoietic stem cells express functional pituitary sex hormone (SexH) receptors. Here we report for the first time that pituitary-secreted gonadotrophins stimulate migration, adhesion, and proliferation of several human myeloid and lymphoid leukemia cell lines. Similar effects were observed after stimulation of human leukemic cell lines by gonadal SexHs. This effect seems to be direct, as the SexH receptors expressed by leukemic cells responded to stimulation by phosphorylation of MAPK_p42/44 and AKT_ser473. Furthermore, in parallel studies we confirmed that human primary patient-derived AML and CML blasts also express several functional SexH receptors. These results shed more light on the potential role of SexHs in leukemogenesis and, in addition, provide further evidence suggesting a developmental link between hematopoiesis and the germline.

Primary diffuse large B-cell lymphoma of the breast: looking at pathogenesis, clinical issues and therapeutic options

Primary breast lymphoma is a rare form of non-Hodgkin lymphoma with some distinct clinical features. The most common histopathological type is diffuse large B-cell lymphoma (DLBCL), but other less frequent subtypes are also encountered. In this review, we describe the characteristics of primary breast DLBCL, with emphasis on pathogenesis, staging, risk stratification and prognosis. In addition, key issues regarding therapy and various available therapeutic modalities are addressed, as well as the role of rituximab in therapy and whether central nervous system prophylaxis is still routinely required. There are very few prospective clinical studies addressing therapy, and available data rely mostly on retrospective case series involving small numbers of patients. Our conclusions and proposed recommendations are therefore not offered as formal guidelines. This review attempts to represent an unbiased analysis of the published data and is intended as a useful aid for clinicians treating this uncommon type of extra nodal lymphoma.

Restraint effects on stress-related hormones and blood natural killer cell cytotoxicity in pigs with a mutated ryanodine receptor

A mutation in the ryanodine receptor gene (RYR1) of the calcium release channel is responsible for increased stress susceptibility in pigs. In the present study, the relation of a mutation in RYR1 with the neuroendocrine (stress-related hormone) response and the immune defense represented by natural killer cell cytotoxicity (NKCC) during a 4-h restraint and recovery phase in 60 male pigs was investigated. Blood samples were collected from pigs previously divided into RYR1 genotypes (nn, Nn, NN), based on PCR amplification and restriction analyses. The blood samples collected during the restraint and recovery phases of the experiment were used to determine NKCC ((51)Cr-release assay), large granular lymphocyte number (hematologic method), and plasma concentrations of prolactin (PRL), GH, ACTH, and cortisol (COR) (by specific RIA). The greatest degree of NKCC response (P < 0.05) to restraint stress relative to controls was observed for the stress-susceptible homozygote group (nn). Measures of stress-related hormones were positively correlated with NKCC during the entire experimental period (P < 0.001 for all investigated hormones) in the nn group. Immunostimulatory effects in the early (0-60 min) phase of restraint were associated with increased hormone responses, especially PRL and GH. In the late (180-240 min) phase of stress and the recovery phase (480 min), a decrease in immune response was accompanied by an elevated COR response in all RYR1 genotypes. Moreover, divergent responses of both PRL (greatest in nn, P < 0.001) and GH (greatest in NN, P < 0.001) to the 4-h restraint were observed. Our results suggest that stress-susceptible RYR1-mutated homozygotes develop a greater level of immune defense, including cytotoxic activity of NK cells, and accompanied by more pronounced stress-induced changes in neuroendocrine response than stress-resistant heterozygous (Nn) and homozygous (NN) pigs.

Prolactin receptor is a negative prognostic factor in patients with squamous cell carcinoma of the head and neck

Background:

The influence of human prolactin (hPRL) on the development of breast and other types of cancer is well established. Little information, however, exists on the effects of hPRL on squamous cell carcinomas of the head and neck (SCCHNs).

Methods:

In this study, we evaluated prolactin receptor (PRLR) expression in SCCHN cell lines and assessed by immunohistochemistry the expression in 89 patients with SCCHNs. The PRLR expression was correlated with clinicopathological characteristics as well as clinical outcome. The effect of hPRL treatment on tumour cell growth was evaluated in vitro.

Results:

Immunoreactivity for PRLR was observed in 85 out of 89 (95%) tumours. Multivariate COX regression analysis confirmed high levels of PRLR expression (>25% of tumour cells) to be an independent prognostic factor with respect to overall survival (HR=3.70, 95% CI: 1.14–12.01; P=0.029) and disease-free survival (P=0.017). Growth of PRLR-positive cancer cells increased in response to hPRL treatment.

Conclusion:

Our data indicate that hPRL is an important growth factor for SCCHN. Because of PRLR expression in a vast majority of tumour specimens and its negative impact on overall survival, the receptor represents a novel prognosticator and a promising drug target for patients with SCCHNs.

Extrapituitary growth hormone

Pituitary somatotrophs secrete growth hormone (GH) into the bloodstream, to act as a hormone at receptor sites in most, if not all, tissues. These endocrine actions of circulating GH are abolished after pituitary ablation or hypophysectomy, indicating its pituitary source. GH gene expression is, however, not confined to the pituitary gland, as it occurs in neural, immune, reproductive, alimentary, and respiratory tissues and in the integumentary, muscular, skeletal, and cardiovascular systems, in which GH may act locally rather than as an endocrine. These actions are likely to be involved in the proliferation and differentiation of cells and tissues prior to the ontogeny of the pituitary gland. They are also likely to complement the endocrine actions of GH and are likely to maintain them after pituitary senescence and the somatopause. Autocrine or paracrine actions of GH are, however, sometimes mediated through different signaling mechanisms to those mediating its endocrine actions and these may promote oncogenesis. Extrapituitary GH may thus be of physiological and pathophysiological significance.

Genetic susceptibility to lymphoma

Genetic susceptibility studies of lymphoma may serve to identify at risk populations and clarify important disease mechanisms. This review considered all studies published through October 2006 on the contribution of genetic polymorphisms in the risk of lymphoma. Numerous studies implicate the role of genetic variants that promote B-cell survival and growth with increased risk of lymphoma. Several reports including a large pooled study by InterLymph, an international consortium of non-Hodgkin lymphoma (NHL) case-control studies, found positive associations between variant alleles in TNF -308G>A and IL10 -3575T>A genes and risk of diffuse large B-cell lymphoma. Four studies reported positive associations between a GSTT1 deletion and risk of Hodgkin and non-Hodgkin lymphoma. Genetic studies of folate-metabolizing genes implicate folate in NHL risk, but further studies that include folate and alcohol intakes are needed. Links between NHL and genes involved in energy regulation and hormone production and metabolism may provide insights into novel mechanisms implicating neuro- and endocrine-immune cross-talk with lymphomagenesis. However, this links will need replication in larger populations. Numerous studies suggest that common genetic variants with low penetrance influence lymphoma risk, though replication studies will be needed to eliminate false positive associations.

Cloning and characterization of the 5'-flanking region of the canine growth hormone gene

The growth hormone (GH) gene is expressed in a variety of tissues outside the pituitary, including the mammary gland. GH expression in the mammary gland is stimulated by progestins. The local synthesis of mammary GH may provide a highly proliferative environment within the mammary gland that may contribute to the development or progression of mammary tumours. To elucidate the mechanism regulating mammary GH expression, we cloned the 5'-flanking region of the canine GH gene using inverse polymerase chain reaction. Gel-shift experiments showed that several sequences in the 5'-flanking region of the GH gene bind mammary nuclear proteins and may be involved in basal and progesterone-induced mammary GH expression. Sequence analysis and comparison with the GH promoters of human, rat, and mouse genes revealed a number of shared binding sites for transcription factors such as Pit-1, which is involved in pituitary GH expression, and for factors involved in the differentiation of lymphoid cells. Moreover, a putative binding site for the progesterone receptor (PR) was identified in all promoters, indicating that the progestin-induced expression of GH in mammary tissue is most probably a direct effect of activated PRs on the GH gene promoter and that this may occur in various species.

Prolactin as an autocrine/paracrine growth factor in human cancer

Prolactin (PRL) has a dual function -- as a circulating hormone and as a cytokine. This understanding is based on PRL production and distinct regulation in extrapituitary sites, its binding to membrane receptors of the cytokine receptor superfamily, and activation of signaling pathways that promote cell growth and survival. There is increasing evidence that PRL plays a role in several types of cancer in reproductive and non-reproductive tissues via local production or accumulation. The expression of both PRL and its receptor in human cancer cell lines of diverse origin lends further support to its action as an autocrine/paracrine growth factor. Establishment of PRL as an active participant in tumorigenesis should inspire the development of novel therapies aimed at reducing tumor growth by suppressing PRL production or by blocking its receptors.

Malignancy and systemic lupus erythematosus

The association of malignancy with systemic lupus erythematosus (SLE) has been investigated for years. The findings of cohort studies lend support for an increased risk of malignancy in SLE but are difficult to interpret definitively. In addition, several cohort studies have suggested an increased risk of non-Hodgkin's lymphoma but with imprecise estimation. There is inadequate evidence for any conclusions about the risk of solid tumors in these patients. A multicenter international research effort is in progress to elucidate these issues and to establish the role of exposures such as cytotoxic or immunomodulatory therapy. The recommendations advocated for cancer screening policies and for minimizing known risk factors for cancer in the general population should not be neglected in persons with SLE.

Prolactin influences proliferation and apoptosis of a human IgE secreting myeloma cell line, U266

In certain types of solid tumours and lymphomas prolactin (PRL) potentiates tumour cell proliferation and exerts anti-apoptotic effect. Tumour cells themselves can produce PRL and express PRL-receptors. Hyperprolactinemia is associated with different tumours, also. Multiple myeloma (MM) is a haematological malignancy caused by the clonal expansion of terminally differentiated plasma cells in the bone marrow. Recently, we demonstrated PRL immunostaining in bone marrow cells of MM patients and an elevated level of serum PRL of MM patients with advanced disease. In the present study, we tested the effect of PRL on a U266 human myeloma cell line and demonstrated constitutive and melphalan-stimulated intracytoplasmic PRL in U266 cells. Exogeneous PRL inhibited the proliferation and immunoglobulin (Ig) production of U266 myeloma cells. Concerning etoposide-induced apoptosis, PRL had a double-faceted effect depending on the applied dose: high, pharmacological doses (corresponding to hyperprolactinemia), inhibited apoptosis, whereas near physiological doses exerted a pro-apoptotic effect. These data indicate a definite effect of PRL on a human myeloma cell line. We demonstrated a direct inhibition of PRL on tumour cell growth, while its reciprocal effect on apoptosis refers to an important regulatory role of PRL.

Upregulation of lymphocyte apoptosis as a strategy for preventing and treating autoimmune disorders: a role for whole-food vegan diets, fish oil and dopamine agonists

Induced apoptosis of autoreactive T-lymphocyte precursors in the thymus is crucial for the prevention of autoimmune disorders. IGF-I and prolactin, which are lymphocyte growth factors, may have the potential to suppress apoptosis in thymocytes and thus encourage autoimmunity; conversely, dietary fish oil rich in omega-3 fats appears to upregulate apoptosis in lymphocytes. Since whole-food vegan diets may downregulate systemic IGF-I activity, it is proposed that such a diet, in conjunction with fish oil supplementation and treatment with dopamine agonists capable of suppressing prolactin secretion, may have utility for treating and preventing autoimmune disorders. This prediction is consistent with the extreme rarity of autoimmune disorders among sub-Saharan black Africans as long as they followed their traditional quasi-vegan lifestyles, and with recent ecologic studies correlating risks for IDDM and for multiple sclerosis mortality with animal product and/or saturated fat consumption. Moreover, there is evidence that vegan or quasi-vegan diets are useful in the management of rheumatoid arthritis, multiple sclerosis, and possibly SLE. The dopamine agonist bromocryptine exerts anti-inflammatory effects in rodent models of autoimmunity, and there is preliminary evidence that this drug may be clinically useful in several human autoimmune diseases; better tolerated D2-specific agonists such as cabergoline may prove to be more practical for use in therapy. The moderate clinical utility of supplemental fish oil in rheumatoid arthritis and certain other autoimmune disorders is documented. It is not unlikely that extra-thymic anti-inflammatory effects contribute importantly to the clinical utility of vegan diets, bromocryptine, and fish oil in autoimmunity. The favorable impact of low latitude or high altitude on autoimmune risk may be mediated by superior vitamin D status, which is associated with decreased secretion of parathyroid hormone; there are theoretical grounds for suspecting that parathyroid hormone may inhibit apoptosis in thymocytes. Androgens appear to up-regulate thymocyte apoptosis, may be largely responsible for the relative protection from autoimmunity enjoyed by men, and merit further evaluation for the management of autoimmunity in women. It will probably prove more practical to prevent autoimmune disorders than to reverse them once established; a whole-food vegan diet, coupled with fish oil and vitamin D supplementation, may represent a practical strategy for achieving this prevention, while concurrently lowering risk for many other life-threatening 'Western' diseases.

Cyclophosphamide plus somatostatin, bromocriptin, retinoids, melatonin and ACTH in the treatment of low-grade non-Hodgkin's lymphomas at advanced stage: results of a phase II trial

PURPOSE

Somatostatin, prolactin, retinoids, melatonin and ACTH have been shown to influence the lymphatic growth, and the action of the cyclophosphamide in lymphoproliferative disorders is well known. This provided the rationale to conduct, in patients with low-grade non-Hodgkin's lymphomas (NHL), a phase II trial of a combined association of cyclophosphamide, somatostatin, bromocriptin, retinoids, melatonin and ACTH.

PATIENTS AND METHODS

Twenty patients with a diagnosis of low-grade NHL, stage III or IV, were included in this study. Patients received for one month the following treatment: cyclophosphamide, somatostatin, bromocriptin, retinoids, melatonin, and ACTH. The therapy was continued for two additional months in patients with stable or responding disease. After three months, the responding patients continued the therapy for three months and more.

RESULTS

Twenty patients were assessable for toxicity and response; 70% (14 of 20 patients; 95% confidence interval [CI], 50% to 90%) had a partial response; 20% (4 of 20) had stable disease, and 10% (2 of 20) progressed on therapy. Going on with the treatment, none of the 14 patients with partial response had a disease progression (average follow-up time of 21 months, range, 7 to 25), and 50% of these patients had a complete response; among 4 patients with stable disease, 25% (1 of 4) had a partial response and 75% (3 of 4) progressed on therapy (mean time to progression [TTP] 14.3 months, range, 7 to 21). The toxicity was very mild, the most common side effects being drowsiness, diarrhea and hyperglycemia.

CONCLUSIONS

The association of cyclophosphamide, somatostatin, bromocriptin, retinoids, melatonin, and ACTH is well tolerated and effective in treatment of low-grade NHL at advanced stage.

Myeloid leukemic cells express and secrete bioactive pituitary-sized 23 kDa prolactin

Prolactin (PRL) is a 23 kDa polypeptide hormone of pituitary origin which is of major importance for reproduction. In addition, PRL has immunomodulatory effects and can be produced in small quantities in nonpituitary tissues. To address possible autocrine or paracrine functions of PRL in leukemia, we characterized immunoreactive PRL from the culture medium of leukemic cells. The myeloid cell line Eol-1 expresses the long extrapituitary type mRNA for PRL and synthesizes immunoreactive PRL with a molecular weight of 23 kDa. The biological activity in Eol-1 culture medium was determined using the Nb2 bioassay. This activity co-eluted with recombinant human (rh) PRL on an S-200 Sephacryl gel filtration column and could be blocked by anti-PRL antiserum. Western blot analysis and Nb2 bioassays also suggest that acute myelogenous leukemic blasts secrete bioactive 23 kDa PRL in one out of three tested patients.