Protection against cyclophosphamide-induced alopecia and inhibition of mammary tumor growth by topical 1,25-dihydroxyvitamin D3 in mice

DNA methylation of microRNA-365-1 induces apoptosis of hair follicle stem cells by targeting DAP3

Background

DNA methylation is a crucial epigenetic alteration involved in diverse biological processes and diseases. Nevertheless, the precise role of DNA methylation in chemotherapeutic drug-induced alopecia remains unclear. This study examined the role and novel processes of DNA methylation in regulating of chemotherapeutic drug-induced alopecia.

Methods

A mouse model of cyclophosphamide (CTX)-induced alopecia was established. Hematoxylin-eosin staining and immunohistochemical staining for the Ki67 proportion and a mitochondrial membrane potential assay (JC-1) were performed to assess the structural integrity and proliferative efficiency of the hair follicle stem cells (HFSCs). Immunofluorescence staining and real-time fluorescence quantitative PCR (RT-qPCR) were performed to determine the expression levels of key HFSC markers, namely Lgr5, CD49f, Sox9, CD200, and FZD10. Differential DNA methylation levels between the normal and CTX-induced model groups were determined through simple methylation sequencing and analyzed using bioinformatics tools. The expression levels of miR-365-1, apoptosis markers, and DAP3 were detected through RT-qPCR and western blotting. In parallel, primary mouse HFSCs were extracted and used as a cell model, which was constructed using 4-hydroperoxycyclophosphamide. The luciferase reporter gene assay was conducted to confirm miR-365-1 binding to DAP3. To measure the expression of relevant indicators, superoxide dismutase (SOD) and malondialdehyde (MDA) kits were used. Methylation-specific PCR (MS-PCR) was performed to determine DNA methylation levels. The regulatory relationship within HFSCs was confirmed through plasmid overexpression of miR-365-1 and DAP3.

Result

In the alopecia areata model, a substantial number of apoptotic cells were observed within the hair follicles on the mouse backs. Immunofluorescence staining revealed that the expression of HFSC markers significantly reduced in the CTX group. Both RT-qPCR and western blotting demonstrated a noteworthy difference in DNA methyltransferase expression. Simple methylation sequencing unveiled that DNA methylation substantially increased within the dorsal skin of the CTX group. Subsequent screening identified miR-365-1 as the most differentially expressed miRNA. miR-365-1 was predicted and confirmed to bind to the target gene DAP3. In the CTX group, SOD and ATP expression markedly reduced, whereas MDA levels were significantly elevated. Cellular investigations revealed 4-HC-induced cell cycle arrest and decreased expression of HFSC markers. MS-PCR indicated hypermethylation modification of miR-365-1 in the 4-HC-induced HFSCs. The luciferase reporter gene experiment confirmed the binding of miR-365-1 to the DAP3 promoter region. miR-365-1 overexpression dramatically reduced apoptotic protein expression in the HFSCs. However, this effect was slightly reversed after DAP3 overexpression in lentivirus.

Conclusion

This study explored the occurrence of miR-365-1 DNA methylation in chemotherapeutic drug-induced alopecia. The results unveiled that miR-365-1 reduces cell apoptosis by targeting DAP3 in HFSCs, thereby revealing the role of DNA methylation of the miR-365-1 promoter in chemotherapeutic drug-induced alopecia.

A novel rat model for chemotherapy-induced alopecia

BACKGROUND

More than half of all people diagnosed with cancer receive chemotherapy, and approximately 65% of these develop chemotherapy-induced alopecia (CIA), a side-effect that can have considerable negative psychological repercussions. Currently, there are very few animal models available to study the mechanism and prevention of CIA.

AIM

To develop a clinically relevant adult rat model for CIA.

METHODS

We first tested whether neonatal pigmented Long-Evans (LE) rats developed alopecia in response to the chemotherapeutic agents etoposide and cyclophosphamide. We then determined whether the rats developed CIA as adults. In the latter experiment, rat dorsal hair was clipped during the early telogen stage to synchronize the hair cycle, and starting 15 days later, the rats were treated with etoposide for 3 days.

RESULTS

Neonatal LE pups developed CIA in response to etoposide and cyclophosphamide, similar to other murine models for CIA. Clipping of the hair shaft during early telogen resulted in synchronized anagen induction and subsequent alopecia after etoposide treatment in the clipped areas only. Hair follicles in the clipped areas had the typical chemotherapy-induced follicular dystrophy (dystrophic catagen). When the hair in the pigmented alopecic areas regrew, it had normal pigmentation.

CONCLUSIONS

A novel, pigmented adult rat model has been established for CIA. By hair-shaft clipping during early telogen, synchronized anagen entry was induced, which resulted in alopecia in response to chemotherapy. This is the first clinically relevant adult rat model for CIA, and will be a useful tool to test agents for the prevention and treatment of CIA.

Stress-induced c-Jun-dependent Vitamin D receptor (VDR) activation dissects the non-classical VDR pathway from the classical VDR activity

Vitamin D receptor (VDR) is a ligand-dependent transcription factor that mediates vitamin D(3)-induced gene expression. Our previous work has established that stress MAPK signaling stimulates VDR expression (Qi, X., Pramank, R., Wang, J., Schultz, R. M., Maitra, R. K., Han, J., DeLuca, H. F., and Chen, G. (2002) J. Biol. Chem. 277, 25884-25892) and VDR inhibits cell death in response to p38 MAPK activation (Qi, X., Tang, J., Pramanik, R., Schultz, R. M., Shirasawa, S., Sasazuki, T., Han, J., and Chen, G. (2004) J. Biol. Chem. 279, 22138-22144). Here we show that c-Jun is essential for VDR expression and VDR in turn inhibits c-Jun-dependent cell death by non-classical mechanisms. In response to stress c-Jun is recruited to the Vdr promoter before VDR protein expression is induced. The necessary and sufficient role of c-Jun in VDR expression was established by the fact that c-Jun knock-out decreases VDR expression, whereas c-Jun restoration recovers its activity. Existence of the non-classical VDR pathway was suggested by a requirement of both c-Jun and VDR in stress-induced VDR activity and further demonstrated by VDR inhibiting c-Jun-dependent cell death independent of its classical transcriptional activity and independent of vitamin D(3). c-Jun is also required for vitamin D(3)-induced classical VDR transcriptional activity by a mechanism likely involving physical interactions between c-Jun and VDR proteins. These results together reveal a non-classical mechanism by which VDR acts as a c-Jun/AP-1 target gene to modify c-Jun activity in stress response through increased protein expression independent of classical transcriptional regulations.

Hairless suppresses vitamin D receptor transactivation in human keratinocytes

The vitamin D receptor (VDR) and its ligand 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] are required for normal keratinocyte differentiation. Both the epidermis and the hair follicle are disrupted in VDR-null mice. Hairless (Hr), a presumptive transcription factor with no known ligand, when mutated, disrupts hair follicle cycling similar to the effects of VDR mutations. Hr, like VDR, is found in the nuclei of keratinocytes in both epidermis and hair follicle. To investigate the potential interaction between Hr and VDR on keratinocyte differentiation, we examined the effect of Hr expression on vitamin D-responsive genes in normal human keratinocytes. Inhibition of Hr expression in keratinocytes potentiated the induction of vitamin D-responsive genes, including involucrin, transglutaminase, phospholipase C-gamma1, and 25-hydroxyvitamin D-24-hydroxylase (24-hydroxylase) by 1,25(OH)2D3. Overexpression of Hr in human keratinocytes suppressed the induction of these vitamin D-responsive genes by 1,25(OH)2D3. Coimmunoprecipitation, DNA mobility shift assays, and chromatin immunoprecipitation revealed that Hr binds to VDR in human keratinocytes. Hr binding to the VDR was eliminated by 1,25(OH)2D3, which recruited the coactivator vitamin D receptor-interacting protein 205 (DRIP205) to the VDR/vitamin D response element complex. These data indicate that Hr functions as a corepressor of VDR to block 1,25(OH)2D3 action on keratinocytes.

Vitamin D protects keratinocytes from apoptosis induced by osmotic shock, oxidative stress, and tumor necrosis factor

Calcitriol, the hormonal form of vitamin D, inhibited caspase-3-like activation in HaCaT keratinocytes exposed to hyperosmotic and oxidative stresses, heat shock, and the inflammatory cytokine TNF. The hormone also protected the cells from caspase-independent cell death induced by hyperosmotic and oxidative stresses. The protection against hyperosmotic stress is not affected by inhibitors of the EGF receptor, ERK or PI13 kinase pathways, neither is it due to reduced activity of the proapoptotic p38 MAP kinase. These results are in accordance with previous in vivo findings that vitamin D protects epidermal keratinocytes from apoptosis due to UV radiation or chemotherapy.

p38 isoforms have opposite effects on AP-1-dependent transcription through regulation of c-Jun. The determinant roles of the isoforms in the p38 MAPK signal specificity

p38 MAPK pathway signaling is known to participate in cell proliferation, apoptosis, and differentiation, in a manner dependent on the cellular context. The factors that determine the specific biological response in a given cell type, however, remain largely unknown. We report opposite effects of the p38 isoforms on regulation of AP-1-dependent activities by p38 activators MAPK kinase 6 (MKK6) and/or arsenite in human breast cancer cells. The p38beta isoform increases the activation of AP-1 transcriptional activities by MKK6 and/or arsenite, whereas p38gamma/p38delta inhibits or has no effect on the stimulation. The p38beta does so by increasing the levels of phosphorylated c-Jun, whereas the p38gamma and -delta isoforms may act by regulating the c-jun transcription. AP-1-dependent processes such as vitamin D receptor gene promoter activation and cellular proliferation were similarly activated by the p38beta or inhibited by the p38gamma and/or -delta isoforms. Whereas the human breast cancer cells express all four isoforms, mouse NIH 3T3 and EMT-6 cells express only some of the p38 family members, with p38beta higher in 3T3 cells but p38delta only detected in the EMT-6 line. Consistent with the positive and negative roles of p38beta and p38delta in AP-1 regulation, MKK6 stimulates AP-1-dependent transcription in NIH 3T3 but not EMT-6 cells. In support of a role of c-Jun regulation by p38 isoforms in determining AP-1 activity, the levels of endogenous c-Jun and its phosphorylated form on p38 activation are higher in NIH 3T3 cells. These results demonstrate the contrasting activities of the different p38 isoforms in transmitting the upstream signal to AP-1 and show that the expression profile of p38 isoforms determines whether the p38 signal pathway activates or inhibits AP-1-dependent processes.

Autoimmune hair loss induced by alloantigen in C57BL/6 mice

Exponentially growing Meth-A cells expressing H-2K(d).D (d) antigen were found to induce alopecia when injected intraperitoneally into normal C57BL/6 mice, which express the H-2K(b).D (b) antigen. However, the capacity to induce alopecia disappeared when Meth-A cells were treated with K252a, which inhibits protein kinases. Histologically, skin in affected areas showed dense mononuclear cell infiltration and a focal foreign-body giant-cell reaction in hair follicles. The subtyping of lymphocytes in peripheral blood demonstrated a significant difference between normal mice and Meth-A cell-injected mice. To further examine the mechanism by which the alloantigen induces alopecia, lymphocytes isolated from the peripheral blood of normal C57BL/6 mice were cultured in medium containing Meth-A cell homogenate, phytohemagglutinin (PHA) and recombinant mouse interleukin-2 (rm IL-2), and intravenously injected into normal C57BL/6 mice. The adoptive transfer of the lymphocytes induced alopecia in a similar way. These findings suggest that the protein kinase-modulated alloantigen induces alopecia by disturbing the immunological homeostasis, and that lymphokine-activated killer cells play an important role in induction of alopecia by cross-reacting with hair follicles.

Relationship between irreversible alopecia and exposure to cyclophosphamide, thiotepa and carboplatin (CTC) in high-dose chemotherapy

Reversible alopecia is a commonly observed, important and distressing complication of chemotherapy. Permanent alopecia, however, is rare after standard-dose therapy, but has occasionally been observed after high-dose chemotherapy with cyclophosphamide, thiotepa and carboplatin (CTC). We evaluated the relationships between total exposure to these three compounds and their different metabolites in the high-dose CTC regimen, and the subsequent development of irreversible alopecia. Twenty-four patients received two or three courses of high-dose CTC, each followed by peripheral blood progenitor cell transplantation. Plasma levels of cyclophosphamide, its active metabolite 4-hydroxycyclophosphamide, thiotepa, its active metabolite tepa, and carboplatin were determined, and the area-under-the-plasma concentration-versus-time curves (AUC) of the compounds were calculated. Eight of the 24 patients included in the study developed permanent alopecia, while seven had normal hair regrowth and nine patients developed incomplete and/or thin hair regrowth. The carboplatin AUC and the summed AUC of thiotepa and tepa were both significantly associated with increasing irreversibility of hair loss. These results suggest that high exposure to carboplatin and the sum of the thiotepa and tepa exposure may lead to the development of permanent alopecia. This knowledge could guide therapeutic drug monitoring in order to prevent the occurrence of permanent alopecia and thereby improve the patients' quality of life.

Antiproliferative effects of 1,25-dihydroxyvitamin D3 on breast cells: a mini review

The hormone 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), the active form of vitamin D3, is an important regulator of calcium homeostasis, exerts antiproliferative effects on various cell systems and can induce differentiation in some kinds of hematopoietic cells. These effects are triggered by its receptor, vitamin D receptor (VDR), a phosphoprotein member of the nuclear receptor superfamily, which functions as a transcriptional factor. VDR binds as a heterodimer with retinoid X receptor (R X R) to hexameric repeats, characterized as vitamin D-responsive elements present in the regulatory region of target genes such as osteocalcin, osteopontin, calbindin-D28K, calbindin-D9K, p21WAF1/CIP1, TGF-beta2 and vitamin D 24-hydroxylase. Many factors such as glucocorticoids, estrogens, retinoids, proliferation rate and cell transformation can modulate VDR levels. VDR is expressed in mammary tissue and breast cancer cells, which are potential targets to hormone action. Besides having antiproliferative properties, vitamin D might also reduce the invasiveness of cancer cells and act as an anti-angiogenesis agent. All of these antitumoral features suggest that the properties of vitamin D could be explored for chemopreventive and therapeutic purposes in cancer. However, hypercalcemia is an undesirable side effect associated with pharmacological doses of 1,25-(OH)2D3. Some promising 1,25-(OH)2D3 analogs have been developed, which are less hypercalcemic in spite of being potent antiproliferative agents. They represent a new field of investigation.

Effect of adenovirus-mediated expression of Sonic hedgehog gene on hair regrowth in mice with chemotherapy-induced alopecia

BACKGROUND

The Sonic hedgehog (Shh) gene is involved in the initiation of hair growth. We have shown that localized, transient, enhanced expression of the Shh gene in mouse skin mediated by an adenovirus (AdShh) vector accelerates initiation of the anagen (i.e., growth) phase of hair follicle development. Because hair regrowth in chemotherapy-induced alopecia is associated with follicle cell proliferation and active melanogenesis similar to that observed in the anagen phase of normal hair growth, we examined whether AdShh-mediated Shh expression would accelerate hair regrowth in the skin of mice with chemotherapy-induced alopecia.

METHODS

After establishment of cyclophosphamide-induced alopecia, in either 3- or 7-week-old mice, AdShh or a control vector (AdNull) was delivered to dorsal skin by intradermal injection. Hair regrowth and melanogenesis were assessed by histology and gross morphology. Fisher's exact test was used to compare differences in outcomes between AdShh-treated and control (AdNull-treated or not injected with any vector [naive]) mice. All statistical tests were two-sided.

RESULTS

Northern blot analysis confirmed enhanced Shh expression after AdShh administration in 7-week-old mice. Two weeks after AdShh administration, the injection site (all of five mice) showed large, anagen-phase hair follicles with a normal distribution of melanin. In contrast, both skin treated with AdNull (all of five mice) and skin from naive mice (all of five mice) showed dystrophic hair follicles with irregular distribution of melanin (P<.001 in both comparisons). Gross morphologic observations confirmed that AdShh-treated mice, but not naive mice or AdNull-treated mice, showed skin darkening at the injection site indicative of entry into anagen phase (P<.001 in both comparisons). AdShh treatment of 3-week-old mice with cyclophosphamide-induced alopecia was followed by accelerated hair follicle recovery (19 of 22 mice); such recovery was not observed at this rate in AdNull-treated or naive skin (P<.001 for both comparisons).

CONCLUSION

Localized, transient, enhanced expression of Shh gene in skin, mediated by an adenovirus vector, might be a future strategy to accelerate hair follicle regrowth after chemotherapy-induced alopecia.

Topical application of cyclosporin A induces rapid-remodeling of damaged anagen hair follicles produced in cyclophosphamide administered mice

Adult C3H mice which had either anagen IV or anagen VI hair follicles were given the anti-tumor drug cyclophosphamide, and cyclosporin A or minoxidil were topically applied to the mice daily from the 4th day after cyclophosphamide administration. In the mice that had anagen IV-hair follicles, 0.5% cyclosporin A induced very thick and long hairs after 21 days of cyclophosphamide administration, while vehicle and 1% minoxidil induced sparsely visible, short hairs. In the mice which received cyclosporin A, the injured hair follicles seemed to remodel themselves into intact anagen hair follicles and restart the production of hairs, instead of shifting to telogen. In the mice that had anagen VI-hair follicles at the time of cyclophosphamide administration, complete alopecia occurred within the first 7 days in all groups. After 14 days of cyclophosphamide administration, hair regrowth was observed in both the 0.5% cyclosporin A-group and the 1% minoxidil- group with the predominant effect over the vehicle. This study shows that anagen hair follicles respond to cyclophosphamide in different ways depending on their stages (IV and VI), and that the damaged anagen IV hair follicles have the potential of remodeling themselves, which is promoted by topical cyclosporin A administration.

A new strategy for modulating chemotherapy-induced alopecia, using PTH/PTHrP receptor agonist and antagonist

Parathyroid hormone (PTH) related peptide (PTHrP) and the PTH/PTHrP receptor (PTH/PTHrP-R) show prominent cutaneous expression, where this signaling system may exert important paracrine and/or autocrine functions, such as in hair growth control. Chemotherapy-induced alopecia - one of the fundamental unsolved problems of clinical oncology - is driven in part by defined abnormalities in hair follicle cycling. We have therefore explored the therapeutic potential of a PTH/PTHrP-R agonist and two PTH/PTHrP-R antagonists in a mouse model of cyclophosphamide-induced alopecia. Intraperitoneal administration of the agonist PTH(1-34) or the antagonists PTH(7-34) and PTHrP(7-34) significantly altered the follicular response to cyclophosphamide in vivo. PTH(7-34) and PTHrP(7-34) shifted it towards a mild form of "dystrophic anagen", associated with a significant reduction in apoptotic (TUNEL+) hair bulb cells, thus mitigating the degree of follicle damage and retarding the onset of cyclophosphamide-induced alopecia. PTH(1-34), in contrast, forced hair follicles into "dystrophic catagen", associated with enhanced intrafollicular apoptosis. We had previously shown that an induced shift in the follicular damage-response towards "dystrophic catagen" mitigates cyclophosphamide-induced alopecia, whereas a shift towards "dystrophic catagen" initially enhanced the hair loss, yet subsequently promoted accelerated hair follicle recovery. Therefore, this study in an established animal model of chemotherapy-induced alopecia, which closely mimics human chemotherapy-induced alopecia, strongly encourages the exploration of PTH/PTHrP-R agonists and antagonists as novel therapeutic agents in chemotherapy-induced alopecia.

Prevention of chemotherapy-induced alopecia in rats by CDK inhibitors

Most traditional cytotoxic anticancer agents ablate the rapidly dividing epithelium of the hair follicle and induce alopecia (hair loss). Inhibition of cyclin-dependent kinase 2 (CDK2), a positive regulator of eukaryotic cell cycle progression, may represent a therapeutic strategy for prevention of chemotherapy-induced alopecia (CIA) by arresting the cell cycle and reducing the sensitivity of the epithelium to many cell cycle-active antitumor agents. Potent small-molecule inhibitors of CDK2 were developed using structure-based methods. Topical application of these compounds in a neonatal rat model of CIA reduced hair loss at the site of application in 33 to 50% of the animals. Thus, inhibition of CDK2 represents a potentially useful approach for the prevention of CIA in cancer patients.

Time-specific occurrence of alopecia in neonatal C57BL mice treated with N-methyl-N-nitrosourea and the therapeutic efficacy of tacrolimus hydrate

Alopecia was induced in male and female neonatal C57BL mice by a single intraperitoneal injection of 60 mg/kg N-methyl-N-nitrosourea (MNU). MNU administration was most effective in the 8-day-old mice and less effective in the 5-day-old mice (at active and early anagen stages of the first hair cycle, respectively). No alopecia was seen in the day 14 MNU-treated animals (at telogen stage of the first hair cycle). MNU effectively induced hair follicular cell apoptosis at the anagen stage by up-regulation of Bax protein without down-modulation of Bcl-2 protein. In day 8 MNU-treated mice, the immunosuppressive agent 0.01% tacrolimus hydrate (FK506), when topically applied for 5 days from 1 day after MNU treatment (before the occurrence of alopecia), decreased the severity of alopecia. However, it did not stimulate hair growth when applied for 5 days from 20 days of age (after occurrence of alopecia).