Altered immune mechanisms play a critical role in the pathogenesis of NHL, as evidenced by increased rates of NHL among HIV-positive patients, transplant recipients, and autoimmune disease patients.92,93 A marked increase in B-cell activation is commonly seen in HIV infection, which is driven by the overproduction of B-cell stimulatory cytokines, such as IL-6 and IL-10, as well as by stimulation of B-cells by HIV and other microbial antigens.94

In addition, HIV itself induces the production of inflammatory cytokines that cause B-cell stimulation, proliferation, and activation, and the cell lines derived from HIV-NHL have been found to express cytokines including interleukin 6, 10, and tumor necrosis factor-α.95–98


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B-cell activation is characterized by lymphocyte proliferation, class switch recombination (CSR), and somatic hypermutation, all of which are prone to resultant errors in DNA that may lead to lymphomagenesis. B-cell activation leads to the expression of activation induced cytidine deaminase (AICDA), a DNA modifying enzyme that mediates immunoglobulin gene CSR and somatic hypermutation.99

Various factors associated with B-cell activation, including B-cell stimulatory cytokines, as well as soluble serum molecules that are associated with B-cell activation, including serum immunoglobulins (Ig) and Ig components such as free light chains, have been seen to be elevated preceding the appearance of HIV-NHL.99,100

In a nested case–control study by Breen and colleagues, it was shown that serum levels of molecules associated with B-cell activation including IL-6, IL-10, C-reactive protein (CRP), sCD23, sCD27, and sCD30 are elevated for several years preceding the diagnosis of systemic HIV-NHL.99,101

In addition, De Roos and colleagues, in a case–control study within Women’s Health Initiative study cohort of 491 cases and 491 controls, showed that women with high serum levels of soluble sCD23, sCD27, sCD30, sCD44, and CXCL13 biomarkers were at 2.8- to 5.5-fold increased risk of B-NHL.92

Furthermore, this was confirmed by Hussain and colleagues, in a nested case–control study of 3768 women, where it was shown that elevated levels of sCD27, sCD30, CD23, and CXCL13 were associated with subsequent diagnosis of HIV-NHL.48

Factors associated with poor clinical outcome and shorter survival in patients with HIV-NHL include CD4 cell count <100 mm3, advanced stage disease (III or IV), age over 35 years, history of injection drug use, elevated serum LDH (above normal), Eastern Co-operative Oncology Group performance status (ECOG PS) of more than 2, and the involvement of more than 2 extranodal sites.102–106

Matthews and colleagues, in a cohort of 7840 HIV-positive patients, showed that age, nadir CD4 cell count, and no prior cART are significantly associated with the development of systemic NHL.107

In addition, Tedeschi and colleagues showed that low CD4 and CD8 cell count and detectable EBV viremia are three independent prognostic biomarkers that might help in the management of HIV-NHL patients.108 Furthermore, higher HIV viral load accompanied by lower CD4 count have been associated with the development of HIV-NHL.109,110 It has been shown that the risk of HIV-NHL rises substantially in patients with HIV RNA levels greater than 100 000 copies/μL and those with CD4 lymphocyte counts of less than 50 mm3/μL.111

HIV-associated Cervical Cancer and its Problems in Diagnosis

Human papillomavirus (HPV) infection is the most important cause of cervical cancer; however, only 2% of cervical HPV will develop into cervical cancer.112 Cervical cancer is caused by a persistent infection with high-risk human papillomavirus (hrHPV) types, which lead to premalignant precursor lesions known as cervical intraepithelial neoplasia (CIN).113

The most common histologic types of cervical cancer are squamous cell (69%) and adenocarcinoma (25%).114 CIN is characterized by abnormal cellular proliferation, maturation, and nuclear atypia.115 CIN may regress to normal or progress to invasive cervical cancer if left untreated.

Approximately, one-third to one half of the cases of CIN I and CIN II regress without treatment. However, the more severe the abnormality of the lesion, the less likely it is to regress.

The accurate grading of CIN lesions is important for clinical management of patients, because CIN I and CIN II/III lesions are treated differently and inaccurate grading results in over or under treatment. This emphasizes the need for specific biomarkers to aid objective CIN grading and to achieve more accurate diagnosis.

Biomarkers Used in HIV-associated Cervical Cancer Diagnosis/Prognosis

The detection of HPV DNA in cervical cancer has been proven to be a good diagnostic and risk predictor tool for cervical cancer (Table 3).116 The oncogenic process in cervical cancer is initiated and mediated by the upregulation of HPV E6/E7 oncoproteins, and thus, overexpression of these oncoproteins is a marker for an increased risk of cervical cancer.117–119

The hrHPV subtypes such as 16 and 18 are thought to play a role in malignant transformation of cells by producing E6 and E7 viral regulatory proteins.33 E6 and E7 are involved in cell proliferation and survival. HPV and oncogene E6 and E7 expressions are the most important markers implicated for cervical cancer.20

Some studies suggest that HPV oncogenes E6 and E7 mRNA levels in the uterine cervix may be more specific early indicators of predisposition to carcinogenesis than DNA levels.120

TABLE 3. Summary of current biomarkers in HIV-associated cervical cancer.

BIOMARKER CHANGES SEEN IN
HIV-ASSOCIATED
CERVICAL CANCER
REFERENCES
HPV DNA Elevated 20,113,118
HPVE6/E7 Elevated 116-120
Ki-67 Elevated 121,124,125
P16 Elevated 113,121,123,124,126
CK17 Elevated 113,126-128
MCM Elevated 129,130,132
CDC6 Elevated 131,132
Ribosomal protein S12 Elevated 133
P53 Elevated 115,125,134
PCNA Elevated 115,135,137
MIB-1 Elevated 137
P63 Suppressed  113,136
CD44 Elevated 138,139
Abbreviations: HPV DNA , Human papillomavirus deoxyribonucleic acid; P16, cyclin-dependent kinase inhibitor p16; CK17, cytokeratin 17; MCM, mini chromosome maintenance protein; CDC6, cell division cycle protein 6; PCNA , proliferating cell nuclear antigen.

Ki-67 is a well-known cell proliferation marker, useful for confirmation of the diagnosis in ambiguous cases of cervical cancer and CIN grading.121 Ki-67 detects a nuclear antigen that is present only in proliferating cells but absent in resting cells.122

Ki-67 has been found to be more intensely stained in HPV-positive than HPV-negative epithelium. P16INK4A (p16) is a cyclin-dependent kinase (cdk) inhibitor that functions as a specific biomarker used for identification of squamous and glandular dysplastic cervical epithelium with tendency to invasive cervical cancer. It has been suggested that p16 is overexpressed in cervical epithelial cells that are transformed in response to the expression of the hrHPV E7 oncoprotein.113

In a nested study by Carozzi and colleagues, it was shown that p16 overexpression is a marker for CIN2 or worse or for its development within 3 years in HPV-positive women.123 Ki-67 and p16 are complimentary alternative biomarkers for HPV-related neoplasia.124,125

Cytokeratin (CK) 17 is a useful marker for endocervical reserve stem cells, which gives rise to metaplasia and antibody to CK17 is used to differentiate between immature squamous metaplasia and high-grade CIN (CIN III).126 CK17 is specific for reserve cells and immature metaplastic cells; it is not expressed in cervical glandular epithelial cells, squamous cells, or mature squamous metaplastic cells.127,128

Overexpression of mini chromosome maintenance (MCM) proteins is seen in severe dysplastic lesions,129,130 and overexpressed cell division cycle protein 6 (CDC6) is observed in malignant cervical cancer.131,132

The ribosomal protein S12 gene has also been reported as an early molecular diagnostic identifier for the screening of cervical cancer and is a potential target in cancer gene therapy trials.122,133

Tumor suppressor protein p53 is a nuclear phosphoprotein encoded by the p53 gene, whose normal function is to control cell proliferation and apoptosis. Mutations of the p53 gene are frequently found in most invasive cancer, resulting in loss of tumor suppressor functions of wild type p53 and gain of oncogenic functions.

Overexpression of p53 has been suggested to be a possible prognostic marker for cervical cancer.134Madhumati and colleagues showed that proliferating cell nuclear antigen (PCNA) and P53 expression increases with increasing severity of CIN lesions.115

It has been previously shown that upregulation of PCNA is closely associated with hrHPV and progressive CIN, but does not predict outcome in cervical cancer.135 P63, which is a member of the p53 gene family, is expressed in the basal and parabasal cells of mature cervical, vaginal, and vulval squamous epithelium, and also in cervical reserve cells at the transformation zone.113,136

It has been shown that MIB-1 may be a useful marker for identification of low-grade CIN lesion with high proliferative index.137 CD44 is a cell adhesion molecule that has been reported to be correlated with poor prognosis in invasive cervical cancer.122,138,139

The increased serum CD4+ and CD8+ T-cell levels and the presence of large number of natural killer (NK) cells have been associated with a favorable response in patients with cervical cancer treated with neo-adjuvant chemotherapy.