Effects of Nerve Growth Factor Expression on Perineural Invasion and Worse Prognosis in Early-Stage Cervical Cancer

Nerve-tumor crosstalk in tumor microenvironment: From tumor initiation and progression to clinical implications

The autonomic nerve system (ANS) innervates organs and tissues throughout the body and maintains functional balance among various systems. Further investigations have shown that excessive activation of ANS not only causes disruption of homeostasis, but also may promote tumor formation. In addition, the dynamic interaction between nerve and tumor cells in the tumor microenvironment also regulate tumor progression. On the one hand, nerves are passively invaded by tumor cells, that is, perineural invasion (PNI). On the other hand, compared with normal tissues, tumor tissues are subject to more abundant innervation, and nerves can influence tumor progression through regulating tumor proliferation, metastasis and drug resistance. A large number of studies have shown that nerve-tumor crosstalk, including PNI and innervation, is closely related to the prognosis of patients, and contributes to the formation of cancer pain, which significantly deteriorates the quality of life for patients. These findings suggest that nerve-tumor crosstalk represents a potential target for anti-tumor therapies and the management of cancer pain in the future. In this review, we systematically describe the mechanism by which nerve-tumor crosstalk regulates tumorigenesis and progression.

BDNF and NGF Expression in Preneoplastic Cervical Disease According to HIV Status

BACKGROUND

Neurotrophins, such as BDNF and NGF, are overexpressed in tumor cells in cervical cancer, and HIV infection is associated with the upregulation of neurotrophin expression. Therefore, we aimed to investigate whether BDNF and NGF are overexpressed in preneoplastic cervical disease from HIV-infected women.

METHODS

Women with preneoplastic cervical lesions (cervical intraepithelial neoplasia grade 2 or 3) were prospectively enrolled and grouped according to their HIV status. Samples from Loop Electrosurgical Excision Procedure (LEEP) for suspected cervical cancer were obtained, and immunohistochemistry was performed to evaluate BDNF and NGF expression.

RESULTS

We included in our analysis 12 HIV-infected patients who were matched with 23 HIV-negative patients as a control group. Immunohistochemistry analysis showed that BDNF expression was significantly higher in cervical preneoplastic lesions from HIV-positive women than in the lesions from the control group. In particular, BDNF was expressed in 8/12 HIV-positive patients and 7/23 HIV-negative patients (66.7% vs. 30.4%, χ² = 4.227; p = 0.040). NGF expression was not significantly higher in cervical preneoplastic lesions from HIV-positive women compared with that in the lesions from the control group. In particular, NGF was expressed in 8/12 HIV-positive patients and in 12/23 HIV-negative patients (66.7% vs. 52.2% χ² = 0.676; p = 0.411). Logistic regression analysis showed that the HIV status is an independent predictor of BDNF expression in pre-invasive preneoplastic cervical disease when considered alone (crude OR 4.6, 95% CI 0.027-20.347; p = 0.046) and when analyzed with other co-factors (adjusted OR 6.786, 95% CI 1.084-42.476; p = 0.041).

CONCLUSIONS

In preneoplastic cervical disease, BDNF expression is higher in HIV-infected women than in non-infected controls, and this is independent of the clinical features of the patients and from the presence of the HPV-HR genotype. BDNF can play a key role as a link between the pathways by which HIV and HPV interact to accelerate cervical cancer progression and invasion. These data can be useful to better understand the role of neurotrophins in the cancerogenesis of cervical cancer and the possible therapeutic strategies to improve disease outcomes.

NGF Signaling Interacts With the Hippo/YAP Pathway to Regulate Cervical Cancer Progression

Nerve growth factor (NGF) is increasingly implicated in cervical cancer progression, but its mechanism in cervical cancer is unclear. Here, studies demonstrate that NGF inhibits the Hippo signaling pathway and activates Yes-associated protein (YAP) to induce cervical cancer cell proliferation and migration. Our results suggested that stimulation of NGF promoted cell growth and migration and activated YAP in HeLa and C-33A cell lines. The expression of YAP target genes (CTGF and ANKRD1) was upregulated after NGF treatment. The NGF inhibitor Ro 08-2750 and siRNA-mediated NGF receptor gene silencing suppressed HeLa and C-33A cells proliferation and migration, activated large suppressor kinase 1 (LATS1) kinase activity, and suppressed YAP function. In addition, the expression of YAP target genes (CTGF and ANKRD1) was suppressed by Ro 08-2750 treatment in HeLa and C-33A cells. Interestingly, proliferation was significantly higher in NGF-treated cells than in control cells, and this effect was completely reversed by the YAP small molecule inhibitor-verteporfin. Furthermore, the mouse xenograft model shows that NGF regulates YAP oncogenic activity in vivo. Mechanistically, NGF stimulation inactivates LATS1 and activates YAP, and NGF inhibition was found to induce large suppressor kinase 1 (LATS1) phosphorylation. Taken together, these data provide the first direct evidence of crosstalk between the NGF signaling and Hippo cancer pathways, an interaction that affects cervical cancer progression. Our study indicates that combined targeting of the NGF signaling and the Hippo pathway represents a novel therapeutic strategy for treatment of cervical cancer.

Perineural Invasion Should Be Regarded as an Intermediate-Risk Factor for Recurrence in Surgically Treated Cervical Cancer: A Propensity Score Matching Study

Background

Perineural invasion (PNI) is considered as a poor prognostic factor in cervical cancer, but there has been no postoperative adjuvant therapy for it, because whether it belongs to high- or intermediate-risk factors has not been determined, this study intends to provide evidences to solve this problem.

Methods

We conducted a retrospective analysis of cervical cancer patients who underwent radical surgery and be reported PNI from January 2012 to June 2017 at the Sun Yat-sen University Cancer Center. After 1 : 1 propensity score matching (PSM), a group of patients without PNI was matched according to the clinical pathological features. Postoperative pathological parameters and prognosis were evaluated between the PNI and the matched groups.

Results

1836 patients were screened, of which 162 (8.8%) diagnosed as stages IB1 to IIB reported PNI. Comparing to the matched group, more PNI (+) patients had deep outer cervix stromal invasion, cervical tunica adventitia invasion, positive lymph nodes, and positive margins. Among patients without high-risk factors, PNI (+) patients had worse 3-year overall survival (90.8% vs. 98.1%, P = 0.02), PNI (+) patients with single intermediate-risk factor and PNI (-) patients who meet with SEDLIS criteria had similar progress free survival (P = 0.63) and overall survival (P = 0.63), even similar survival curves.

Conclusion

PNI is related to a worse overall survival among cervical cancer patients without high-risk factors and play the role as an intermediate-risk factor.

Stress Hormones: Emerging Targets in Gynecological Cancers

In the past decade, several discoveries have documented the existence of innervation in ovarian cancer and cervical cancer. Notably, various neurotransmitters released by the activation of the sympathetic nervous system can promote the proliferation and metastasis of tumor cells and regulate immune cells in the tumor microenvironment. Therefore, a better understanding of the mechanisms involving neurotransmitters in the occurrence and development of gynecological cancers will be beneficial for exploring the feasibility of using inexpensive β-blockers and dopamine agonists in the clinical treatment of gynecological cancers. Additionally, this article provides some new insights into targeting tumor innervation and neurotransmitters in the tumor microenvironment.

Unveiling the pathogenesis of perineural invasion from the perspective of neuroactive molecules

Perineural invasion (PNI) is characterized by an encounter between the cancer cells and neuronal fibers and holds an extremely poor prognosis for malignant tumors. The exact molecular mechanism behind PNI yet remains to be explored. However, it is worth-noting that an involvement of the neuroactive molecules plays a major part in this process. A complex signaling network comprising the interplay between immunological cascades and neurogenic molecules such as tumor-derived neurotrophins, neuromodulators, and growth factors constitutes an active microenvironment for PNI associated with malignancy. The present review aims at discussing the following points in relation to PNI: a) Communication between PNI and neuroplasticity mechanisms can explain the pathophysiology of poor, short and long-term outcomes in cancer patients; b) Neuroactive molecules can significantly alter the neurons and cancer cells so as to sustain PNI progression; c) Finally, careful manipulation of neurogenic pathways and/or their crosstalk with the immunological molecules implicated in PNI could provide a potential breakthrough in cancer therapeutics.

Nerve growth factor and its receptor tyrosine kinase TrkA are overexpressed in cervical squamous cell carcinoma

Nerve growth factor (NGF) and its receptors are increasingly implicated in cancer progression, but their expression in cervical cancer is unclear. The objective of this study was to define the protein expression of NGF, its precursor (proNGF), as well as their receptors, the tyrosine kinase receptor TrkA, the common neurotrophin receptor p75NTR and the pro-neurotrophin receptor sortilin in cervical cancer. Immunohistochemistry was performed in a cohort of cervical cancers (n = 287), including the two major subtypes of the disease: squamous cell carcinomas (SCC) and adenocarcinomas (AC). Normal cervical tissues (n = 28) were also analyzed. Protein expression was determined by computer-based digital quantification of staining intensity and comparative statistical analyses were made with clinicopathological parameters including histological subtype, age, grade, tumor size, lymph node invasion, and stage. The expression of NGF, proNGF, TrkA, p75NTR, and sortilin was higher in cervical cancer compared to normal cervical tissues. NGF and TrkA were found overexpressed in SCC compared to AC (P = .0006 and P < .0001, respectively). The expression of NGF (P = .0053), proNGF (P = .0022), and p75NTR (P = .0002), but not that of TrkA or sortilin, was associated with increasing grade in SCC. In addition, nerve infiltration into the tumor microenvironment was assessed using the pan-neuronal marker PGP9.5. Infiltrating nerves were detected in 27% of cervical tumors and expressed TrkA. Functional investigations using the HELA cervical cancer cell line indicated that the Trk tyrosine kinase inhibitor GNF-5837 reduced cell viability through decreased ERK1/2 activation. Together, these data reveal the overexpression of NGF and TrkA in cervical SCC, suggesting a potential therapeutic value of targeting the NGF-TrkA signaling pathway in this subtype of cervical cancer.