Angiotensins II and IV modulate adrenocortical cell proliferation in ovariectomized rats.

Effects of angiotensins II (AngII), angiotensin IV (AngIV, 3-8 fragment of angiotensin II) and losartan (an antagonist of angiotensin receptor type 1) on the proliferation of adrenocortical cells in ovariectomized rats have been studied. The incorporation of bromodeoxyuridine (BrdU) into cell nuclei was used as an index of cell proliferation. AngIV decreased BrdU labeling index mainly in the reticularis zone and losartan (Los) was able to partially reverse this inhibitory effect of AngIV. AngII had no effect on the adrenocortical cell proliferation when given alone, however Los given simultaneously diminished BrdU incorporation into nuclei of glomerulosa and reticularis zones as compared with AngII. These findings suggest that AngII and AngIV modulate adrenocortical cell proliferation in ovariectomized rats.

Expression of p65 gene in experimental colon cancer under the influence of 5-fluorouracil given alone and in combination with hormonal modulation.

The effect of tamoxifen (TAM), lanreotide (LAN) and 5-fluorouracil (5-FU), given separately or together, on p65 gene expression in murine Colon 38 cancer was investigated by RT-PCR method. The findings were compared with cell proliferation determined by bromodeoxyuridine (BrdU) labeling index, apoptosis visualized by TUNEL method and tumor mass. It was found that in the control group (mice bearing colon cancer without treatment) the expression of p65 gene was present in 57% of investigated samples. In the groups treated with TAM or LAN p65 gene expression was detected in 87.5% and 83.3% of analyzed cases, respectively. Both these substances increased apoptotic index in Colon 38 cancer and LAN also decreased the proliferation index. After a combined treatment with TAM and LAN a percentage of p65 positive cases was similar to that of the control group and equaled approximately 60%. This treatment did not increase proapoptotic effects of these drugs, and even reduced the antiproliferogenic effect of LAN. In the group treated with 5-FU and LAN p65 gene expression was also close to the control value (about 66%). Similarly in this group the combined treatment with these two drugs did not cause any favorable effect on proliferation and apoptosis. Moreover, in this group even reduced antiproliferogenic effect of LAN was observed. In the group with 5-FU alone the expression of p65 was present in about 80% of samples. The treatment with 5-FU increased apoptotic index and did not change proliferation. In the group treated with a combination of TAM and 5-FU all analyzed cases showed the presence of p65 gene expression. Previously, we observed in this group the most pronounced and synergistic effect of these substances on the inhibition of cell proliferation and tumor mass reduction. Based on these findings we conclude that p65 gene expression in murine Colon 38 cancer tissues can be modulated via chemotherapy (5-FU) and also via hormonal modulation (TAM and LAN).

Angiotensins II and IV stimulate the rat adrenocortical cell proliferation acting via different receptors.

OBJECTIVE: The effects of angiotensins II (Ang II) and IV (Ang IV,3-8 fragment of angiotensin II) on the adrenocortical cell proliferation have been investigated in the rat. METHODS: The male adult Wistar rats were injected subcutaneously with saline, captopril or captopril together with either Ang II or Ang IV. A part of animals received additionally losartan - an antagonist of AT1 subtype of angiotensin receptors. Bromodeoxyuridine (BrDU) incorporation into cell nuclei was used as the index of cell proliferation. RESULTS: It was found that both Ang II and Ang IV increased the BrDU labeling in the adrenal cortex of captopril-pretreated rats. This effect involved mainly the zona glomerulosa cells. The proliferogenic effect of Ang II was blocked by AT1 receptor antagonist losartan. In contrast, losartan did not block the effect of Ang IV. CONCLUSION: Both Ang II and Ang IV stimulate the adrenocortical cell proliferation in the rat, but they act via different receptors - AT1 in the case of Ang II and non-AT1 (probably AT4) in the case of Ang IV.

Effects of short term treatment with pentagastrin, proglumide, tamoxifen given separately or together with 5-fluorouracil on the growth in the murine transplantable Colon 38 cancer.

It is well known that 5-fluorouracil (5-FU) is the most effective drug in the treatment of colon cancer, however the positive response is small, only about 20%. On the other hand, it has been postulated that the growth of colon cancer depends on many growth factors, such as gastrin and estrogens. The search for new substances increasing the antitumor effect of 5-FU has lasted for many years. The aim of the present study was to examine the effects of pentagastrin (PEN, syntetic gastrin analogue), proglumide (PRO, a blocker of gastrin receptor) and tamoxifen (TAM, a partial estrogen antagonist) given separately or together with 5-FU on proliferation, apoptosis, necrosis and proliferation/apoptosis (P/A) ratio in the murine transplantable Colon 38 cancer. The male mice were implanted with a suspension of Colon 38 cells. After 7 days, the animals were treated with PEN (250 microg/kg b.w., twice daily), PRO (100 mg/kg. b.w., twice daily), TAM (10 microg/animal) separately or together with 5-FU (60 mg/kg b.w., once) for 2 days. The incorporation of bromodeoxyuridine (BrdU) into cell nuclei was used as an index of cell proliferation (labeling index--LI). The in situ labeling of nuclear DNA fragmentation according to TUNEL method was considered as an apoptotic index (AI). It was found that 5-FU increased the apoptosis, unexpectedly increased the LI and decreased the P/A ratio when compared to control. Both PEN and PRO increased the apoptosis and in the case of PRO decreased P/A ratio when compared to control. TAM did not affect any of the examined parameters. All of the investigated substances modify the 5-FU action: PEN and PRO on AI and LI and TAM on AI and P/A ratio. Necrosis was observed in 3 tumors treated with PEN + 5-FU, in 2 tumors of PRO + 5-FU group and in 1 tumor of group with 5-FU and with PEN. Further studies are needed to elucidate if those modification of 5-FU action by the examined substances will be useful in the inhibition of the growth of Colon 38 cancer.

The involvement of angiotensins in the control of prostatic epithelial cell proliferation in the rat.

The effects of captopril (the inhibitor of the angiotensin-converting enzyme) and of angiotensins II and IV (3-8 fragment of angiotensin II) on cell proliferation of the prostatic epithelium was investigated in the rat. The incorporation of bromodeoxyuridine into cell nuclei was used as an index of cell proliferation. It was found that the treatment with captopril resulted in the suppression of prostatic epithelial cell proliferation. The antiproliferative effect of captopril was reversed (at least partially) by a simultaneous treatment with either angiotensin II or angiotensin IV. The effects of angiotensins were not blocked by the administration of losartan--AT1 angiotensin receptor blocker. These findings suggest the involvement of angiotensins in the control of prostatic growth, acting via the receptors different from the AT1-subtype (presumably via AT4 receptors).

The involvement of the renin-angiotensin system in the regulation of cell proliferation in the rat endometrium.

Oestrogens are known to enhance angiotensin biosynthesis by increasing the elaboration of its precursor, angiotensinogen. On the other hand, we found that inhibition of angiotensin-converting enzyme (ACE) suppressed the proliferative response of the rat anterior pituitary gland to oestrogens. To answer the question whether the angiotensin system is involved in the control of the cell proliferation of the uterine epithelium, the effects of an ACE inhibitor, enalapril maleate, and of angiotensins II and IV, alone or together with losartan, an antagonist of angiotensin receptor type 1 (AT1), on endometrial epithelial cell proliferation have been studied. The experiments were performed on ovariectomized female Wistar rats. In the first experiment the animals were injected with a single dose of oestradiol benzoate or received an injection of solvent only. Half of the oestrogen-treated rats were injected additionally with enalapril maleate (EN, twice daily). The incorporation of bromodeoxyuridine (BrDU) into endometrial cell nuclei was used as an index of cell proliferation. It was found that oestradiol alone dramatically increased the BrDU labelling index (LI) of endometrial cell nuclei, and this effect was partially blocked by the simultaneous treatment with EN. In the second experiment, the animals were injected intraperitoneally with angiotensin II (AII), angiotensin IV (AIV) or saline, alone or together with losartan. It was found that AIV induced an increase in the LI in uterine epithelium, and this effect was not blocked by the simultaneous treatment with losartan. The increase in LI in uterine epithelium was also observed in the rats treated with AII and with losartan. These findings suggest an involvement of angiotensin IV in the control of uterine epithelium cell proliferation.

Somatostatin analogue octreotide and melatonin inhibit bromodeoxyuridine incorporation into cell nuclei and enhance apoptosis in the transplantable murine colon 38 cancer.

There is much evidence of the antiproliferative activity of somatostatin (SS) and melatonin (Mel) upon the normal and neoplastic tissues. It has also been found, that both substances are able to alter, under certain conditions, apoptotic processes. Recently, it has been postulated that apoptosis plays a pivotal role in the control of tumour growth. So far, there is no data about the effect of SS analogue--octreotide (Sandostatin, SMS) and Mel on the apoptosis of colon cancer cells. The aim of this study is to examine the effects of SMS and Mel administered separately or together on apoptosis, bromodeoxyuridine incorporation and weight of tumours in the murine transplantable Colon 38 cancer. The male mice were implanted subcutaneously (s.c.) with a suspension of Colon 38 cells. After 6 days, the animals were subcutaneously injected with SMS, Mel, SMS and Mel together (once daily at 6-8 p.m., for 6 days). The incorporation of bromodeoxyuridine (BrDU) into cell nuclei was used as an index of cell proliferation (labelling index-LI). The in situ labelling of nuclear DNA fragmentation according to TUNEL method was considered as an apoptotic index (AI). Given separately, both SMS and Mel significantly decreased the LI and increased the AI. However, we have not observed any additive effect of SMS and Mel on either BrDU incorporation or apoptosis. The mean AI in the group treated jointly with SMS and Mel was significantly lower than in groups treated separately with SMS or Mel. It was also found, that the proliferation/apoptosis ratio were significantly lower in the group treated with SMS or MEL, which means that the imbalance between these two processes changed in favour of cell death. Possibly, the observed antitumour effects of these two substances could be due to this alteration.