Biological Activities of Synthesized 20K and 22K hGH in Nb2 Bioassay and IM-9 Radioreceptor Assay.

Ohmae, Yumi; Yano, Hisako; Umezawa, Sachiko; Tanaka, Toshiaki; Hibi, Itsuro; Miyamoto, Chikara; Furuichi, Yasuhiro

doi:10.1507/endocrj1954.36.9

Cited by 13 publications

(8 citation statements)

References 17 publications

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“…The discrepancy between Fig. 2, A and B, although a similar one has also been raised by other groups (7,26), prompted us to investigate the 20K-hGH in the Ba/ F3-hPRLR cell assay in spite of already published data of 20K-hGH examined in Nb2 cell assay (22,23). Figure 3A shows the dose-response curves of 20K-and 22K-hGH in the absence of exogenous Zn 2ϩ .…”

Section: Proliferation Of Ba/f3-hprlr and Nb2 Cells Stimulated By Wilmentioning

confidence: 69%

“…For instance, the two hGH isoforms were equipotent in the pigeon crop-sac assay (21), whereas 20K-hGH had only 10.7ϳ12.5% activity as compared with 22K-hGH in the absence of Zn 2ϩ in rat Nb2 cell growth assay (22,23). Several groups had explained this discrepancy by the slower metabolic clearance rate of 20K-hGH (37), the existence of serum binding protein specific for 20K-hGH (38), or the unique dependency of the rat PRLR-mediated activity of 20K-hGH on Zn 2ϩ concentration (39).…”

Section: Discussionmentioning

confidence: 99%

“…With respect to PRLR-mediated actions of 20K-hGH, several foregoing data exist. For example, 20K-and 22K-hGH were equipotent in pigeon crop-sac bioassay (21); in contrast, 20K-hGH had only 10.7ϳ12.5% the potency of 22K-hGH in Nb2 cell bioassay in the absence of Zn 2ϩ (22,23) and 16.5% in the binding analysis with the extracellular domain of hPRLR (hPRLbp) in the presence of 50 m Zn 2ϩ (24). However, these reports have given us no information about the effect of 20K-hGH on the full-length hPRLR.…”

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confidence: 99%

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The 20-Kilodalton (kDa) Human Growth Hormone (hGH) Differs from the 22-kDa hGH in the Effect on the Human Prolactin Receptor

et al. 1999

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Previously we have demonstrated that 20-kDa human GH (20K-hGH) is a full agonist for hGH receptor (hGHR) even though its complex formation with hGHR and hGH-binding protein differs from that of 22-kDa human GH (22K-hGH). In this study, we focused on the effect of 20K-hGH on human PRL receptor (hPRLR). To elucidate the effects of 20K-hGH on hPRLR and compare them with those of 22K-hGH, we prepared two cells stably expressing full-length hPRLR, Ba/F3-hPRLR and CHO-hPRLR. In the proliferation of Ba/F3-hPRLR cells, which can grow in a dose-response to lactogenic hormones, both 20K- and 22K-hGH exhibited bell-shaped curves in the absence of exogenous zinc ion (Zn2+); however, the curve of 20K-hGH was shifted to a 10-fold higher concentration than that of 22K-hGH in view of EC50 value (the EC50 of 20K- and 22K-hGH were 15 nM and 1.5 nM, respectively). Addition of Zn2+ up to 25 microM increased the activities of both 20K- and 22K-hGH; however, the enhancement by Zn2+ was greater in 20K-hGH than in 22K-hGH, thereby the activities of both hGH isoforms reached the same level at 25 microM Zn2+. Nevertheless, in the presence of 0.25-1 microM free Zn2+, which is equal in human serum, the activity of 20K-hGH was still lower than that of 22K-hGH. The modest effect of 20K-hGH on activating hPRLR in the absence of Zn2+ was confirmed in the rat serine protease inhibitor 2.1 (Spi2.1) gene promoter activation and JAK2/Stat5 tyrosine phosphorylation in CHO-hPRLR. In addition, in human breast cancer cell T-47D, 20K-hGH was proved to stimulate Stat5 tyrosine phosphorylation to much lower degree than 22K-hGH via not hGHR but hPRLR. Taken together, our data suggest that 20K-hGH may be a weaker agonist for hPRLR than 22K-hGH in the human body; therefore 20K-hGH may alleviate the hPRLR-mediated side-effects such as breast cancer when administered to human body.

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Section: Proliferation Of Ba/f3-hprlr and Nb2 Cells Stimulated By Wilmentioning

confidence: 69%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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The 20-Kilodalton (kDa) Human Growth Hormone (hGH) Differs from the 22-kDa hGH in the Effect on the Human Prolactin Receptor

et al. 1999

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“…Since IL-6 is involved in osteoclastogenesis in the bone marrow, leading to bone resorption [8], it is likely that hGH stimulates not only bone formation but also bone resorption, leading to the acceleration of bone remodeling [3]. [12][13][14][15]. Recently, recombinant 20K-hGH with a natural sequence was synthesized and it was found that the recombinant 20K-and 22K hGH increases body weight in rats equipotently [16] and that both hGHs have the same affinity constant for hGH receptors transiently expressed on CHO cells [17].…”

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confidence: 99%

Osteo-Anabolic Effects of Human Growth Hormone with 22K- and 20K Daltons on Human Osteoblast-Like Cells.

et al. 1999

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“…Previously, it was reported that 20K-hGH bound to rat GH receptor (rGHR) with 3–10% affinity of 22K-hGH [2, 3, 4]. Additionally it was also reported that 20K-hGH activated rat prolactin receptor (rPRLR) 11–13% as compared with 22K-hGH by rat lymphoma Nb2 cell proliferation [5, 6]. In contrast, 20K-hGH showed the similar growth-promoting activity to 22K-hGH in the rat weight gain [7, 8, 9].…”

Section: Introductionmentioning

confidence: 99%

Cellular Activities of 20K- and 22K-hGH Do Not Necessarily Correlate with Their Binding Affinities for Rat GH Receptor

Ikeda¹,

Matsumoto²,

Uchida³

et al. 2000

Horm Res Paediatr

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Even though 20K human growth hormone (20K-hGH) has 3–10% binding affinity for the rat liver and adipose tissue microsomes as compared to 22K-hGH, it was also reported that 20K-hGH has the same potency as 22K-hGH in the hypophysectomized rat weight gain assay. In order to investigate the reason why such controversial data exist, we have studied 20K- and 22K-hGH using the rat GH receptor extracellular domain (rGHR-ECD) and full-length rGHR. When we examined the complex formation of rGHR-ECD with 20K- and 22K-hGH in gel filtration assay, 20K-hGH formed no complex while 22K-hGH formed a 1:1 complex. Next, rGHR cDNA was introduced into Ba/F3 cells and CHO-K1 cells, and stable transfectants (Ba/F3-rGHR and CHO-rGHR) were established. In the proliferation of Ba/F3-rGHR cells, 20K-hGH had 10-fold lower activity than 22K-hGH, which is consistent with their affinities for rGHR. But surprisingly, in the Spi2.1 gene promoter activation in CHO-rGHR cells, 20K- and 22K-hGH had the same activity, which was found not only in stable CHO-rGHR clones but also in CHO-K1 cells transiently expressing rGHR. In conclusion, these results indicate that cellular activities of 20K- and 22K-hGH do not necessarily correlate with their binding affinities for rGHR.

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Biological Activities of Synthesized 20K and 22K hGH in Nb2 Bioassay and IM-9 Radioreceptor Assay.

Cited by 13 publications

References 17 publications

The 20-Kilodalton (kDa) Human Growth Hormone (hGH) Differs from the 22-kDa hGH in the Effect on the Human Prolactin Receptor

The 20-Kilodalton (kDa) Human Growth Hormone (hGH) Differs from the 22-kDa hGH in the Effect on the Human Prolactin Receptor

Osteo-Anabolic Effects of Human Growth Hormone with 22K- and 20K Daltons on Human Osteoblast-Like Cells.

Cellular Activities of 20K- and 22K-hGH Do Not Necessarily Correlate with Their Binding Affinities for Rat GH Receptor

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