Parathyroid hormone related protein and interleukin-6 mRNA expression in larynx and renal cell carcinomas from normocalcaemic and hypercalcaemic patients

Parathyroid hormone-related peptide and parathyroid hormone-related peptide receptor type 1 in locally advanced laryngeal cancer as prognostic indicators of relapse and survival

Background

Parathyroid hormone-related peptide (PTHrP) overexpression and poor patient outcome have been reported for many human tumors, but no studies are available in laryngeal cancer. Therefore, we studied the expression of PTHrP and its receptor, parathyroid hormone-related peptide receptor type 1 (PTH1R), in primary locally advanced laryngeal squamous cell carcinomas (LALSCC) also in relation to the clinical outcome of patients.

Methods

We conducted a retrospective exploratory study, using immunohistochemistry, on PTHrP, PTH1R and HER1 expressions in LALSCC of 66 patients treated with bio-radiotherapy with cetuximab.

Results

The expressions of PTHrP and PTH1R in LALSCC were associated with the degree of tumor differentiation (p = 0.01 and 0.04, respectively). Poorly differentiated tumors, with worse prognosis, expressed PTHrP at nuclear level and were PTH1R negative. PTHrP and PTH1R were expressed at cytoplasmic level in normal larynx epithelium and more differentiated laryngeal cancer cells, suggesting an autocrine/paracrine role of PTHrP in squamous cell differentiation of well differentiated tumors with good prognosis. Eighty-one percent HER1 positive tumors expressed PTHrP (p < 0.0001), mainly at nuclear level, consistent with the known up-regulation of PTHrP gene by HER1 signaling. In multivariable analyses, patients with PTHrP positive tumors had a higher relative risk of relapse (HR = 5.49; CI 95% = 1.62–22.24; p = 0.006) and survival (HR = 8.21; CI 95% = 1.19–105.00; p = 0.031) while those with PTH1R positive tumors showed a lower relative risk of relapse (HR = 0.18; CI 95% = 0.04–0.62; p = 0.002) and survival (HR = 0.18; CI 95% = 0.04–0.91; p = 0.029).

Conclusions

In LALSCC nuclear PTHrP and absence of PTH1R expressions could be useful in predicting response and/or resistance to cetuximab in combined therapies, contributing to an aggressive behavior of tumor cells downstream to HER1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09748-1.

Structure-based virtual screening and characterization of a novel IL-6 antagonistic compound from synthetic compound database

According to the three-dimensional (3D) complex structure of (hIL-6⋅hIL-6R⋅gp 130)₂ and the binding orientation of hIL-6, three compounds with high affinity to hIL-6R and bioactivity to block hIL-6 in vitro were screened theoretically from the chemical databases, including 3D-Available Chemicals Directory (ACD) and MDL Drug Data Report (MDDR), by means of the computer-guided virtual screening method. Using distance geometry, molecular modeling and molecular dynamics trajectory analysis methods, the binding mode and binding energy of the three compounds were evaluated theoretically. Enzyme-linked immunosorbent assay analysis demonstrated that all the three compounds could block IL-6 binding to IL-6R specifically. However, only compound 1 could effectively antagonize the function of hIL-6 and inhibit the proliferation of XG-7 cells in a dose-dependent manner, whereas it showed no cytotoxicity to SP2/0 or L929 cells. These data demonstrated that the compound 1 could be a promising candidate of hIL-6 antagonist.

The therapeutic potential of interleukin-6 hyperagonists and antagonists

Interleukin-6 (IL-6) is a 4-helical protein that binds to a specific IL-6 receptor on target cells and to two molecules of the promiscuous signal transducing protein, glycoprotein 130 (gp130). Structure-function analysis has led to the definition of molecular contacts between IL-6 and its receptor subunits. This knowledge has led to the design of competitive antagonistic proteins that retain their receptor binding capability, but fail to stimulate one or both gp130 proteins; the properties of such recombinant antagonistic proteins are compared with traditional neutralising monoclonal antibodies targeted at IL-6 or receptor subunits. Furthermore, several strategies have been employed to construct molecules with increased bioactivity. Possible therapeutic applications in putative IL-6 dependent haematologic disorders, e.g., Castleman's disease (CD), POEMS syndrome, multiple myeloma, and bone diseases, e.g., Paget's disease, osteoporosis, are outlined. IL-6 antagonists could also, in theory, suppress inflammatory activity in rheumatic and autoimmune diseases and could prevent secondary amyloidosis. This principle may prove advantageous in myocardial infarction (MI) and unstable angina pectoris. More generally, IL-6 antagonists could improve the wasting and microcytic anaemia of chronic diseases. IL-6 antagonists might slow down development of mesangio-proliferative glomerulonephritis (MPGN). Hyperagonistic variants of IL-6 have a potential use in the ex vivo expansion of haematopoietic progenitor cells and as thrombopoietic agents. They might well be the first drugs to aid liver regeneration in vivo.

Suppression of cancer cachexia by 20S,21-epoxy-resibufogenin-3-acetate—a novel nonpeptide IL-6 receptor antagonist

While screening for novel IL-6 inhibitors, we synthesized 20S,21-epoxy-resibufogenin-3-acetate (ERBA). ERBA dose-dependently suppressed IL-6-induced cell growth with an IC(50) value of 5.3 microM and caused a parallel rightward shift of dose-response curves to IL-6. Analysis of data yields a pA2 of 5.83 and a slope of 0.99. ERBA did not affect IL-2-, IL-3-, and GCSF-dependent cell growth, or tumor necrosis factor alpha-induced growth suppression, nor did ERBA affect osteoclast formation induced by IL-11, leukemia inhibitory factor, and 1alpha,25-dihydroxyvitamin D(3). Receptor assay showed that ERBA dose-dependently suppressed IL-6 binding to IL-6 receptor (IL-6R). Furthermore, no band existing at the position of IL-6R in Western blots of ERBA-treated cells when stimulated with IL-6:ERBA suppresses IL-6 activity by blocking the binding of IL-6 to IL-6R. In an experimental model of colon 26-induced cancer cachexia, ERBA markedly inhibited body weight loss. ERBA is a specific small molecule with IL-6R-antagonist activity.

Biological activity of a novel nonpeptide antagonist to the interleukin-6 receptor 20S,21-epoxy-resibufogenin-3-formate

Interleukin (IL)-6 is a key mediator in the regulation and coordination of the immune response and participates in pathogenesis of cancer cachexia, autoimmune disease, and postmenopausal osteoporosis. In the course of a screening program aimed at IL-6 inhibitor from natural products, we isolated 20S,21-epoxy-resibufogenin-3-formate (ERBF) from bufadienolide and examined the effect of ERBF on activities of various cytokines. ERBF dose dependently suppressed IL-6 activity and caused a parallel rightward shift of dose-response curves to IL-6 at concentrations of 0.03 to 10 ng/ml. Analysis of data yields a pA(2) of 5.12 and a slope of 0.99. Selectivity of ERBF on activity of cytokines was examined using cytokine-dependent cell lines. ERBF did not affect IL-2-dependent growth of CTLL-2 cells, IL-3-dependent growth of Baf3 cells, or tumor necrosis factor (TNF)alpha-induced growth suppression in TNFalpha-sensitive L929 cells. ERBF also did not affect IL-4-stimulated expression of FcepsilonR II receptor (CD23) in U-937 cells, the IL-8-induced chemotaxis of human neutrophils, or nerve growth factor-stimulated neuronal differentiation in PC-12 cells. In contrast, ERBF dose dependently suppressed IL-6-induced neuronal differentiation in PC-12 cells. Furthermore, ERBF suppressed only IL-6-induced osteoclast formation without affecting osteoclast formation induced by IL-11, leukemia inhibitory factor, and 1alpha,25-dihydroxyvitamin D(3). In receptor binding assay, unbound (free) IL-6 was increased in a dose-dependent manner by pretreatment with ERBF on IL-6 receptor (IL-6R), suggesting that ERBF suppresses binding of IL-6 to IL-6R. These results clearly indicate that ERBF is a novel specific small molecule to show IL-6 receptor antagonist activity.

Hypercalcemia associated with parathyroid hormone-related protein at the terminal stage of uncomplicated squamous cell carcinoma in the head and neck region

BACKGROUND

Parathyroid hormone-related protein (PTHrP) is mainly responsible for hypercalcemia in squamous cell carcinomas (SCCs).

METHODS

We retrospectively checked the appearance of hypercalcemia among 33 patients who died with head and neck SCC. Serum concentrations of C-terminal region of PTHrP (C-PTHrP) were measured in 15 of them. The intracellular PTHrP expression was immunohistochemically stained in 42 SCC sections obtained from the 33 before the appearance of hypercalcemia.

RESULTS

Hypercalcemia appeared in 24 of the 33, and increased serum C-PTHrP levels were confirmed in 11 of 12 hypercalcemic patients. PTHrP was identified in all SCC sections, and a stronger intensity than in normal squamous epithelia was observed in 50% of those obtained within 1 year before the onset of hypercalcemia.

CONCLUSION

A high incidence of PTHrP-induced hypercalcemia was shown among patients dying with head and neck SCCs. The intracellular increase in PTHrP might be observed preceding hypercalcemia.

The role of interleukin-6 in the induction of hypercalcemia in renal cell carcinoma transplanted into nude mice

Hypercalcemia is a well known complication of renal cell carcinoma (RCC). As RCCs can produce IL-6, and IL-6 may stimulate bone resorption and cause mild hypercalcemia, we examined whether IL-6 is involved in renal cancer-associated hypercalcemia in vivo. Three human renal cell carcinoma tumor lines (RC-8, RC-9, and NC-65) growing in nude mice were studied. Tumors were implanted s.c., and parameters of bone metabolism and serum human IL-6 levels were determined in relation to tumor volume (TV). All three tumor lines secreted human IL-6, although in different quantities. The maximum level of IL-6 in RC-8 was 434 pg/ml (TV, 200 mm3), that in RC-9 was 81 pg/ml (TV, 1800 mm3), and that in NC-65 was 2368 pg/ml (TV, 1800 mm3). Hypercalcemia developed in RC-8 and RC-9 tumor-bearing animals, but not in NC-65-bearing animals. The hypercalcemia in both RC-8 and RC-9 tumor lines was associated with elevated levels of PTH-related peptide (PTHrP) and loss of trabecular bone volume. Serum calcium and phosphate concentrations showed an almost linear relationship with plasma PTHrP independently of the tumor line and serum IL-6 levels. No hypercalcemia occurred in the NC-65 animals, which had the highest levels of IL-6, but no detectable plasma PTHrP and PTHrP messenger RNA expression in the tumor. Administration of neutralizing antibodies to IL-6 to RC-8 animals normalized serum calcium concentrations and PTHrP values and induced a significant inhibition of tumor growth. No such effect on tumor growth of anti-IL-6 was seen in the other two tumor lines. The normalization of serum calcium in RC-8 mice is most likely attributed to the growth-inhibiting effect of anti-IL-6 on RC-8 tumor. We conclude that IL-6 secreted by RCC does not contribute directly to hypercalcemia, but may enhance hypercalcemia by stimulating the tumor growth of a subpopulation of PTHrP-secreting carcinomas.