Vanilloid Receptor (TRPV1) Expression on the Neoplastic B-Cell Lymphocytes in Patients with Chronic Lymphocytic Leukaemia.

Background:

Endocannabinoids take part in physiology of neural and immune system. Last data showed that these compounds and their receptors play an important role in proliferation and apoptosis of different neoplastic cells. Cannabinoids were shown to increase the apoptosis in human neoplastic cells through a number of mechanisms including vanilloid receptors (Sanchez et al. 1998, Maccarone et al. 2000). The vanilloid receptor family of cation channels includes the capsaicin-sensitive, proton- and heat-activated vanilloid receptor type I (TRPV1). Furthermore Saunders et al. (2006) showed that TRPV1 are expressed on normal lymphocytes in human peripheral blood.

Aims:

The aim of our study was the assessment of receptor TRPV1 mRNA expression in the lymphocytes B derived from patients with newly diagnosed chronic lymphocytic leukaemia.

Material and methods:

The study group contains newly diagnosed, untreated adult patients with B-cell chronic lymphocytic leukaemia; 11 males and 10 females, aged from 46 to 74. The patients were in A-C stage according to Binet. We used 13 samples from healthy donors as a control group. The isolation of mononuclear cells from peripheral blood was carried out with the use of density centrifugation method. The resolution of mononuclear cell population to lymphocytes B subpopulation was done with negative isolation method utilizing magnetic microballs (Dynal). Total RNA was isolated from B-lymphatic cells of which 10ng was used in each reaction. Quantitative RT-PCR was carried out with the use of Light Cycler (Roche) and respective commercial kits. The nucleotides sequence of the studied receptor and parameters of the amplification process were based on method previously described by Qiao et al (2003). We used house keeping gene hexose-6-phosphate dehydrogenase (glucose 1-dehydrogenase) (G6PDH) as a reference gene. Amplification product was sequenced by ABI PRISM (Applied Biosystem). All results are presented as a mean concentration ratio of TRPV1 to G6PDH mRNA ± standard error. Statistical analysis was performed using Shapiro-Wilk, non parametric U Mann-Whitney Tests.

Results:

We found that concentration ratio of studied transcript was significantly lower in the study group in comparison to the control group (0,048± 0,012 vs. 106,836± 40,215 respectively. We found no differences between the subgroups irrespectively of gender, age, stage of the disease and some prognostic factors (LDH, lymphocyte doubling time, β2-microglobulin).

Conclusions:

The results confirm the existence of vanilloid receptors on the lymphocytes B of healthy individuals and for the first time show presence of this type of receptors in CLL group. The lower level of TRPV1 transcripts in the group of patient may suggests their potential role in the process of leukemic transformation. Thus the effect of endocannabinoids through this receptor may be altered in CLL. However, further studies are required to elucidate the nature of relationship between this type of receptor and neoplastic development of CLL.